Search

Climate and land management affect nutrient cycling in grassland ecosystems. We aimed to understand whether temperate and tropical grasslands differ in terms of soil organic carbon (SOC), nitrogen (N), and phosphorus (P) concentrations, and their C:N:P stoichiometric ratios in grazed and ungrazed natural grasslands and pastures. For this, we used a meta-analysis approach (1296 records, 241 papers), and regression models to explain the observed patterns in terms of mean annual precipitation (MAP), mean annual temperature (MAT), altitude, and latitude. SOC, N, and P concentrations were higher in temperate regions than in tropical ones, and they negatively correlated with MAT and MAP. The grassland type effect was more significant for tropical regions. In tropical regions, soil C:N ratios were higher in ungrazed than in grazed pastures, and soil N:P ratios in ungrazed sites were higher in pastures than in natural grasslands. Grazing increases soil N and SOC for natural grasslands in temperate regions. Our findings suggest that soil stoichiometric C:N:P stoichiometric signatures in grasslands differed between tropical and temperate regions on a global scale. P is a key element in regulation and restriction on soil C and N cycling in tropical regions but less in the temperate ones. Our findings suggest the direction of effects of grazing or grassland type on C:N:P stoichiometric signature. Since imbalances in soil stoichiometric ratios may have implications for ecosystem functioning, the assessment of these patterns could serve as a valuable tool for management and conservation of grasslands and pastures in both tropical and temperate regions. [ABSTRACT FROM AUTHOR]

As arid lands expand across the globe, scholars increasingly turn to the archaeological record for examples of sustainable farming in extreme environments. The arid north coast of Peru was the setting of early and intensive irrigation-based farming; it is also periodically impacted by sudden, heavy rainfall related to the El Niño Southern Oscillation (ENSO) phenomenon. While the sociopolitical effects, technologies, and engineering expertise of these irrigation systems have been thoroughly examined and theorized, little is known about how farmers managed periods of water stress. The aim of this study is to test whether arid zone farming was supported by hybrid, intermittent flood and perennial water source systems in the prehispanic past. An arroyo in the Chicama Valley was selected for preliminary data collection, and these data are presented here: (1) drone photography of the arroyo capturing the aftermath of a recent (2023) rain event; and (2) potassium (K) soil test kit results from samples collected near suspected prehispanic check dam features in the same area. The paper combines these data with comparative examples from the literature to suggest that the prehispanic features functioned as water-harvesting infrastructure. The paper concludes that sustainable, arid zone farming can be supported by hybrid, intermittent flood and perennial water source systems. [ABSTRACT FROM AUTHOR]

[Objective] The paper aimed to study the effects of biochar application on the quality of cured tobacco, soil mutrients and soil microbial community structure. (Method) A randomised block group field experiment was conducted using Yunyan 87 as the experimental mate rial. Four treatments were set up (SWT1: Conventional fertilization; SWT2: Conventional fertilization biochar 1500 kg/hm²; SWT3: Conventional fertilization + biochar 2250 kg/hm²; SWT4: Conventional fertilization biochar 3000 kg/hm²) to determine the chemical composition, sensory quality of cured tobacco and the soil nutrients, rhizosphere soil hacterial diversity of the cured tobacco at maturity. [Result] The application of biochar had no significant influence on the soil nutrients and chemical composition of cured tobacco. Compared with the SWTI treatment, the sensory quality of cured tobacco was significantly improved in all treatments of biochar application, among which SWT3 treat- ment showed the best performance with 13.85%,6.56%,10.87%,8.70%,4.62%,12.31% and 6.25% improvement in amma quality, aroma amount, concentration, strength, impurities, usage value, and total score, respectively. With the increase of biochar application rate, the bacterial richness (Chaol index), diversity (Shannon indes), total ASV number and unique ASV number in the rhizosphere soil of flue- cured tobacco showed a decreasing trend. Compared with SWT1 treatment, the difference in microbial community structure composition incre aed with the increase of biochar application rate. The dominant phyla of each treatment were Proteobacteria, Acidobacteria and Actinobacte ria, At the phylum classification level, there was no significant difference in the community structure composition among different treatments. The application of biochar increased the relative abundance of f Rhizobiaceae, g Allorhizobium, Neorhizobium, g Pararhizobium, g Rhizobium and other nitrogen fixing bacteria, as well as funcultured_Actinobacterium, f Burkholderiaceae, Pseudomonadaceae, o Pseudomonadale, g Pseudomonas, g Sphingopyxis, & Dyella, g Massilin and other growth promoting bacteria. The application of biochar decreased the relative abundance of denitrifying bacteria such as sunclassified_Anaerolinencrar and g unclassified Caulobacteracene. At the ASV classification level, AN was the dominant factor affecting the changes in soil bacterial community structure. [Conclusion] The application of biochar improve the sensory quality of cured tobacco leaves, with SWT3 treatment (2250 kg/hm²) performing the best. The application of biochar reduce thizosphere soil bacteria a-diversity, and increase the relative abundance of beneficial hacteria such as nitrogen fixing bacteria, growth promoting bacteria, and denitrifying bacteria in the thizosphere soil, which is beneficial for increasing soil nutrients and promoting plant growth. [ABSTRACT FROM AUTHOR]

In agriculture, soil is a vital element that decides the quality and yield of agricultural produce. Soil consists of various nutrients such as nitrogen (N), phosphorous (P), potassium (K), the potential of hydrogen (pH), and water content. Nitrogen is responsible for building chlorophyll, which helps produce proteins and thus directly contributes to plant growth and development. Phosphorous is needed to develop root systems and flowers, whereas potassium helps increase disease resistance. Each of these play a role in crop cultivation. Thus, in this research paper, considering the fact that soil health will provide farmers with the best selection of crops that are compatible with their farm's soil nutrients, we propose an algorithm for recommending a set of suitable crops based on various soil attributes. These soil nutrients can be collected in real-time using soil sensors, such as N, P, K, and pH, and humidity sensors. They can be deployed in farms where the cultivation takes place. These sensor readings would then be transferred to the blockchain layer, thereby validating the data and ensuring it is tamper-proof and evident. The crop recommendation model uses data from these sensors in real-time, increasing the results' accuracy. The last stage leads us to display these results via a user dashboard, which helps the farmers to keep in check with their farm's practices, and their sensor states from remote locations. [ABSTRACT FROM AUTHOR]

[Objective] Soil organic carbon (SOC) and nutrient content are not only the key indicators of soil quality health evaluation, but also the limiting factors for the sustainable development of alpine and high altitude ecosystems in the plateau. The present paper aimed to explore the current status and influencing factors of soil surface nutrients in alpine swamp meadow, and to determine the fertilizer supply capacity of the soil type. [Method) Taking the alpine swamp meadow soil at the southern foot of the Qilian Mountains as the research object, and referring to the China Second Soil Census Nutrient Grading Standard, selecting pH, organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), available nitrogen (AN), available phosphorus (AP), available potassium (AK) for the depth of 0-10 and 0-20 cm soil carbon, nitrogen, phosphorus, potassium content and ecological stoichiometric characteristics were analyzed. [Result] The soil layers with 0-10 cm content of organic carbon (SOC), total nitrogen (TN), available nitrogen (AN), available phosphorus (AP) and available potassium (AK) higher than 10-20 cm, pH, total phosphorus (TP) content did not change significantly, total potassium (TK) content increased slightly. The ecological stoichiometric characteristics showed that the C/P and N/P of the 0-10 cm soil layer were higher than 10-20 cm, and the N/P was lower than that 10-20 cm soil layer. On the whole, the pH of the alpine swamp meadow soil was neutral-weakly acidic, and the rank sequence of soil nutrient content was organic carbon (SOC) total nitrogen (TN) ≈ available nitrogen (AN) > total phosphorus (TP) > total potassium (TK) > available potassium (AK) > available phosphorus (AP). The organic carbon (SOC), total nitrogen (TN) and available nitrogen (AN) were at the first level, belonging to the rich level; Total phosphorus (TP) was at the second level, belonging to the relatively rich level; Total potassium (TK) was at the third level, belonging to the middle level; Available potassium (AK) was at the fourth level, belonging to the relatively lack level; Available phosphorus (AP) was at the sixth level, belonging to the exigence level. [Conclusion] The decomposition and mineralization rate of organic matter in the 0-20 cm soil layer of alpine swamp meadow in the southern foot of Qilian Mountains is slow, organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP) are abundant, and N and Pavailability is low. The research results provide references for soil health, quality evaluation and ecological restoration in the alpine region of the Qinghai-Tibet Plateau. [ABSTRACT FROM AUTHOR]

【Objective】 The present paper aimed to explore the changes of physicochemical properties and soil enzyme activities that are closely related to the occurrence of continuous cropping obstacles after the application of exogenous Methyl jasmonate（MeJA）.【Method】The three-year continuous cropping soil and red cheek strawberry were used in this paper to study the changes of physicochemical properties and soil enzyme activities of strawberry rhizosphere soil after applying different concentrations（0, 10, 50, 100, 200, 500 μmol/L） of exogenous MeJA. Indicators such as soil nutrient content, soil pH, soil enzyme activity, fruit number per plant, and single fruit weight were investigated.【Result】 Compared with CK treatment without MeJA, the contents of organic matter, alkali hydrolyzable nitrogen, available phosphorus and potassium of strawberry rhizosphere soil treated with MeJA decreased in general, which mostly significant, whether in the seedling stage or the flowering and fruiting stage; The pH of MeJA treatment was higher than that of the control treatment, and reached a significant level at the seedling stage, with an increase range of 3.90%-5.58%; The activities of peroxidase, polyphenol oxidase, protease and urease of MeJA treatment were generally improved compared with the control treatment, and most of them reached a significant degree; Compared with CK, MeJA treatment significantly reduced the plant height of strawberry by 22.33%-27.19%, and increased the number of strawberries per plant, of which treatment with 100 μmol/L MeJA increased by 26.25%. The effects of different concentrations of MeJA on the single fruit weight of strawberry showed a trend of increasing first and then decreasing, and the specific order was 100>50>10>0>200>500 μmol/L. Compared with CK, treatments with 50 μmol/L and 100 μmol/L significantly increased by 4.02%-31.60%. After the application of exogenous methyl jasmonate, the changes of soil nutrients, pH and soil enzyme activities in strawberry rhizosphere showed a transition rule at 100 μmol/L or its adjacent concentration with the increase of MeJA concentration. 【Conclusion】 After the application of an appropriate amount of exogenous methyl jasmonate, the continuous cropping strawberry showed that the rhizosphere soil nutrients were more absorbed, the soil acidification degree was alleviated, and the soil enzyme activity increased, which increased the number of fruits per plant and the single fruit weight of strawberries. However, the above trend was reversed with increasing MeJA concentrations. The above findings were beneficial to guide the production practice to apply exogenous methyl jasmonate to improve the physicochemical properties and soil enzyme activities of continuous cropping strawberry rhizosphere soil, so as to promote plant growth and alleviate continuous cropping obstacles. [ABSTRACT FROM AUTHOR]

[Objectives] This paper aimed to explore the effects of reasonable straw return on water quality, soil nutrients and enzyme activities in rice-shrimp fields under the rice-crayfish integrated breeding mode. [Methods] The field experiment was carried out in 2019, and four treatments were set up, including the straw was not returned to the field without nitrogen fertilizer (CK), and the amount of straw returned to the field is 1 500 kg·hm-2(S1N1), the amount of straw returned to the field was 3 500 kg·hm-2(S2N2), and the amount of straw returned to the field was 4 500 kg·hm-2(S3N3). Water quality, soil nutrients and soil enzyme activities were determined. [Results]The dissolved oxygen in water was 6.68-14.59 mg·L-1. The total phosphorus and active phosphorus contents in water increased in different straw returning treatments compared with CK treatment. After 95 d of straw returning, the nitrate nitrogen content in water decreased with the increase of straw returning; the contents of nitrite nitrogen and ammonia nitrogen in the water under different treatments decreased. After straw returning, the maximum increase of soil total phosphorus content was 36.86% under the treatment of S3N3. Soil ammonium nitrogen reached the peak after 30 d of straw returning, and soil nitrate nitrogen content increased with the increase of straw returning. The three straw returning treatments decreased the soil urease activity, but increased the soil alkaline phosphatase activity. After straw returning to the field, the soil sucrase activity of CK and S1N1 treatments increased slightly, the largest increase of soil sucrase activity was observed in S3N3 treatment (118.30%), which was significantly higher than other treatments. [Conclusions] Different straw returning treatments had no adverse effects on water quality, the treatment with the amount of straw returned to the field of 4 500 kg·hm-2 was better than other treatments in terms of soil nutrients and enzyme activity. [ABSTRACT FROM AUTHOR]

The effective use of nutrient-rich crop straw is an important way to use resources efficiently and to sustain agricultural development. This meta-analysis study collected and analyzed the data of 6788 observations published in 238 peer-reviewed papers to investigate differences in soil C-N fractions and yields of paddy soils under different straw-return amounts. This large dataset was also used to quantify the degree of influence of factors such as climate characteristics, soil properties, N fertilizer application rates, straw-rotting agent addition, rice varieties, and straw return methods. The results showed that straw return amounts improved soil alkaline-hydrolysable N (7%), total N (10%), organic C (11%), the C:N ratio (8%), rice N accumulation (12%), and overall yield (18%). The most significant effect was in northeast China fields for total soil nitrogen (TN) content and yield with increases of 13% and 22%, respectively. We also found more effective N utilization and a greater rice yield when 220–260 kg ha−1 N fertilizer was applied with 20–30 kg ha−1 straw-rotting agent with the total amount of straw return. These findings have important implications for choosing appropriate conditions and field management practices and to improve rice yield in China. [ABSTRACT FROM AUTHOR]

In the present situation, plants have to meet the food supply demand for a large and increasing population. In order to get high yield, it is essential for the plantations to be nourished with soil containing an appropriate amount of nutrients like Nitrogen (N), Phosphorus (P) and Potassium (K). Various methods such as, physical (optical) and chemical (electrochemistry) have been adopted to analyze the soil nutrients. This paper reviewed optical methods of soil nutrient detection suitable for building a portable sensor because it can sense nutrients in dry soil samples directly without the need for complicated sample pretreatments. We concentrate and elaborate on optical methods of experimentation. Starting from laboratory testing standards followed in India we move on to off the lab crude methods like soil testing kits and colorimetric approaches. Further, we review the effective and utilitarian spectroscopic approaches and also the technologically advanced and latest methods like imaging systems, microfluidic, and micro-electromechanical system (MEMs) based sensors. However, optical methods are affected by environmental factors that affect the accuracy of sensor results. This paper then discusses boons and curses of optical methods of soil nutrient sensing. It also explains briefly the working of each method and mentions the most recent advancements made in the given testing method. We hope that this paper can serve as a guide for the experimenters and give a direction for carrying out further work required in developing a portable and efficient soil NPK detection sensor. [ABSTRACT FROM AUTHOR]

The aim of this paper was to study the characteristics of litter decomposition-soil and nutrients-soil enzymes and their correlations among different forest types in the south subtropical coastal land to reveal the mechanism of nutrient migration in coastal forest ecosystems and provide a scientific basis for their protection and restorations. Two typical secondary forests, Ficus altissima and Syzygium hancei, and Acacia mangium artificial forest were chosen as research objects to analyze the litter decomposition. The dynamic variation rules of soil nutrients and soil enzyme activities of the three stand types and their correlations were analyzed. The results showed that the litter decomposition rate was F. altissima forest＞Syzygium hancei forest＞A.mangium forest. The soil nutrient content was the highest in F.altissima forest or Syzygium hancei forest, and the lowest in A.mangium forest. The dynamic variation of the same soil enzyme activity was basically the same in the three stand types, and the enzyme activity peaked in August or November. Some differences in the correlation between the litter loss, soil nutrients, and soil enzymes were observed among the three stand types. Soil sucrase (SUC) activity in F. altissima and in Syzygium hancei forest was extremely significantly (P＜0.01) and significantly (P＜0.05) positively correlated with total nitrogen (TN) content, respectively. The catalase (CAT) activity of A. mangium forest was extremely significantly (P＜0.01) with available nitrogen (AN) content, and significantly (P＜0.05) positively correlated with total phosphorus (TP) content.The litter decomposition rate and soil nutrient content of the secondary forests of F.altissima and Syzygium hancei were better than those of the A.mangium forest. Therefore, in the process of restoring and maintaining coastal soil fertility, priority should be given to protecting natural vegetation and creating near-natural stratified forests according to the characteristics of native tree species to improve the ability of sandy soil to “self-fertilize”and accelerate the process of vegetation restoration and succession. [ABSTRACT FROM AUTHOR]

To explore the differences and change rules of soil nutrients and enzyme activities in Larix gmelinii forest in the cold temperate zone, so as to provide scientific basis and data basis for in-depth understanding of forest ecosystem functions and future development trends in the cold temperate forest ecotone in China. In this paper, four different types of larch forest (Betula platyphylla -Larix gmelinii, Rhododendron dauricum-Larix gmelinii, Larix gmelinii, and Larix gmelinii plantation) in Heilongjiang Zhongyangzhan Black-Billed Capercaillie Nature Reserve were selected as the research objects. Sampling was carried out by season, and the soil. chemical properties and enzyme activities ( catalase, acid phosphatase, urease, sucrase and cellulase) were determined in different seasons, and the dynamic changes with seasons were also explored. Results showed that: (1) Soil chemical properties and enzyme activities were significantly different in different forest types and seasons, and the changing trends were also different to some extent. (2)Soil acid phosphatase was significantly affected by the contents of soil total P, total N and available K. Soil catalase was significantly positively correlated with the contents of total N, available N, available K and available P. Soil sucrase was mainly affected by the contents of available P and available N. Soil urease and cellulase were most affected by soil organic carbon content. (3)The principal component analysis showed that there were significant differences in soil enzyme activities and soil chemical properties among the four forest types, and first principal component 1 could explain more than 50% of the variance variables. The soil chemical properties and enzyme activities in different Larix gmelinii were significantly different with the seasons, which were related to the accumulation of litter and the difference of vegetation types. Soil enzyme activities were correlated with soil chemical properties to varying degrees. [ABSTRACT FROM AUTHOR]

[Objective] In order to explore the effects of low nitrogen stress on the growth and soil nutrients of tartary buckwheat in the hilly and gully regions of the Loess Plateau, the present paper determined plants and soil characteristics of tartary buckwheat with different nitrogen stress among the whole growth period It could provide a scientific basis for the optimal management of farmland nitrogen fertilizer in the loess hilly and gully region. [Method] The study took different nitrogen buckwheat (Heifeng No. 1, HF, intolerant to low nitrogen, Diqing Tartary Buckwheat, D Q, tolerant to low nitrogen) as the research objects, and set 3 levels of nitrogen application as follows : 0 kg/hm² (NO, no nitrogen treatment), 80 kg/hm² (Nl, low-nitrogen treatment), 160 kg/hm² (N², normal nitrogen treatment). Plant indexes (plant height, stem thickness, leaf area) and soil characteristics (soil water content, pH, organic matter, alkali-hydrolyzed nitrogen, available phosphorus, available potassium, total nitrogen, total phosphorus, total potassium) were determined during the whole growth periods. [Result] (i) Cultivar, nitrogen treatment and the interaction between the two had extremely significant effects on tartary buckwheat plants (P < 0. 01 ). Under Nl treatment, the plant height, stem thickness and leaf area of DQ in the seedling stage were 9. 7 %, 10. 5 %, and 17. 7 % higher than that of HF. The plant height and stem thickness of DQ in the flowering stage were 9. 5 % and 7. 4 % higher than that of HF. The stem thickness and leaf area of DQ were 5. 4 % and 3 6. 2 % higher than those of HF. (ii) The cultivars, nitrogen treatments and the interaction between the two had a significant impact on soil nutrients (P < 0. 01). After the growth period, the soil nutrient indexes of the two cultivars were lower than those of the sowing period, but soil organic matter, available nitrogen, available phosphorus, available potassium, total nitrogen, and total potassium of DQ were higher than those of HF under Nl treatment of98. 8%, 11. 6%, 44. 7%, 11. 6%, 80. 41%, 4. 2%, respectively. [Conclusion] The DQ (low nitrogen tolerant) has better water conservation and green manure benefits than HF (intolerant to low nitrogen) as its larger leaf area and stem thickness could buffer the direct erosion of rainfall on the ground and resist wind to prevent plant lodging. In addition, the rhizosphere soil nutrient content of DQ was higher than HF after being harvested which could reduce the fertilizer consumption in the next season and was also more conducive to the sustainable development of agriculture. [ABSTRACT FROM AUTHOR]

[Objective] In order to explore the effects of low nitrogen stress on the growth and soil nutrients of tartary buckwheat in the hilly and gully regions of the Loess Plateau, the present paper determined plants and soil characteristics of tartary buckwheat with different nitrogen stress among the whole growth period It could provide a scientific basis for the optimal management of farmland nitrogen fertilizer in the loess hilly and gully region. [Method] The study took different nitrogen buckwheat (Heifeng No. 1, HF, intolerant to low nitrogen, Diqing Tartary Buckwheat, D Q, tolerant to low nitrogen) as the research objects, and set 3 levels of nitrogen application as follows : 0 kg/hm² (NO, no nitrogen treatment), 80 kg/hm² (Nl, low-nitrogen treatment), 160 kg/hm² (N², normal nitrogen treatment). Plant indexes (plant height, stem thickness, leaf area) and soil characteristics (soil water content, pH, organic matter, alkali-hydrolyzed nitrogen, available phosphorus, available potassium, total nitrogen, total phosphorus, total potassium) were determined during the whole growth periods. [Result] (i) Cultivar, nitrogen treatment and the interaction between the two had extremely significant effects on tartary buckwheat plants (P < 0. 01). Under Nl treatment, the plant height, stem thickness and leaf area of DQ in the seedling stage were 9. 7 %, 10. 5 %, and 17. 7 % higher than that of HF. The plant height and stem thickness of DQ in the flowering stage were 9. 5 % and 7. 4 % higher than that of HF. The stem thickness and leaf area of DQ were 5. 4 % and 3 6. 2 % higher than those of HF. (ii) The cultivars, nitrogen treatments and the interaction between the two had a significant impact on soil nutrients (P < 0. 01). After the growth period, the soil nutrient indexes of the two cultivars were lower than those of the sowing period, but soil organic matter, available nitrogen, available phosphorus, available potassium, total nitrogen, and total potassium of DQ were higher than those of HF under Nl treatment of98. 8%, 11. 6%, 44. 7%, 11. 6%, 80. 41%, 4. 2%, respectively. [Conclusion] The DQ (low nitrogen tolerant) has better water conservation and green manure benefits than HF (intolerant to low nitrogen) as its larger leaf area and stem thickness could buffer the direct erosion of rainfall on the ground and resist wind to prevent plant lodging. In addition, the rhizosphere soil nutrient content of DQ was higher than HF after being harvested which could reduce the fertilizer consumption in the next season and was also more conducive to the sustainable development of agriculture. [ABSTRACT FROM AUTHOR]

Soil microbial community plays important role in maintaining the soil sustainability and is integrally related to soil fertility since provides the accessibility and cycling of nutrients in organic niches. Different parameters, characterizing the structure and activity of soil microbiome usually serve as indicators for reclamation effectiveness. Among them, the basal soil respiration, microbial biomass carbon content, microbial density and diversity are widely used all over the world as a measure of the progress of bio-transforming processes and the turnover of soil into a functioning ecosystem. Based on these parameters this paper aimed to establish the microbiome status and determinants in natural and reclaimed soils affected by pyrogenic carbon emissions in the area of Maritsa-Iztok lignite basin and particularly to reveal the response of microorganisms to such anthropogenic influence. Pyrogenic carbon (PyC) is a climate-warming agent and its influence on biological and chemical processes in soils is of paramount importance nowadays in view of the amplification of climate changes. In this part of the study, data on three reclaimed soils (Spolic Technosols) located close to Maritsa-Iztok industrial complex are presented. The results obtained show that the basic feature of studied Tecnosols is the different depth of the humus horizon formed by reclamation and this together with their proximity to the main source of pyrogenic carbon ("Maritsa-Iiztok 2" Thermal Power Plant) determines the observed differences in the activity, density and behavior of different microbial groups. The general hallmark of studied microbial populations was the strong density decrease in sub-horizons, active participation in the biochemical transformations of organic matter, including the stable fraction of PyC and low need of endogenous available nitrogen. Likewise the natural soils oligotrophic, heterotrophic and ologonitrophilic bacteria prevailed in Technosols but mainly oligotrophs and ologonitrophils showed asynergetic behavior in respect of other microorganisms and were capable to utilize the exogenous nutrients equally well. Due to the extremely high spatial variation of oligonitrophils density this group could be used as bioindicator of soil anthropogenization especially of pyrogenic carbon (PyC) accumulation. Only organic carbon, PyC (with small exceptions) and available potassium determined the microbial growth and density in studied Technosols while pH, humic acids, available nitrogen and clay contents were not significant factors. Availablity of phosphorus positively influenced microbiome status only in Technosols occupied by perennial crops (profiles 2 and 3) with exception of asynergetic groups. In low content of organic carbon and prevailing mineralization processes carbonates become important determinant of microbiome activity. [ABSTRACT FROM AUTHOR]

Soil microorganisms rapidly respond to anthropogenic changes and are useful indicators for perturbations in the soil matrix or the reclamation effect on mine spoils. This paper aimed to establish the microbiome status and determinants in natural and reclaimed soils affected by pyrogenic carbon emissions in the area of Maritsa-Iztok lignite basin and particularly to reveal the response of microorganisms to such anthropogenic influence. Pyrogenic carbon (PyC) is formed during the combustion of fossil fuels or vegetation and has multiple negative impacts on climate, public health and environment. Nowadays its influence on biological and chemical processes in soils is of paramount importance in view of the amplification of climate changes. In this part of the study two typical for the region natural soils Smolnitsa type (Pellic Vertisol) were analysed. The first soil (profile 1) is situated far from the mining region and hence was chosen for a referent soil. Samples from genetic horizons of soils, as well as from the surface horizon of vulnerable soil (located between the two sources of PyC) were collected by pit trial technique and monitoring approach on 2-th of June 2018. Data obtained showed that due to the inherent three dimensional variations of soil properties, the different crops and cultivation manner, microbial features (microbial biomass carbon and population density) of natural Pellic Vertisols predominately varied in depth but followed the typical for native soils trend of decreasing amounts down the profiles. In both soils, heterotrophic, oligotrophic and oligonitrophilic bacteria were the most numerous groups but in the deepest horizons only oligotrophs dominated. The oligotroph-pedoturbation observed in A'"k and ACk horizons as an atypical population decline is a specific feature of studied Smolnitsas. Due to the high spatial variation of oligonitrophilic bacteria density this group could be used as bioindicator of soil anthropogenization including pyrogenic carbon (PyC) accumulation. Data suggests that additional inputs of PyC in soils surrounding coalfield could decouple SOM and PyC, supress microbiome synergy and dependency on PyC. Only some nutrients (organic carbon, phosphorus, potassium and easily mobile humic and fulvic acids) determined the microbial growth and density in studied soils while soil moisture, depth, carbonates and clay contents were not significant factors. Available nitrogen positively influenced microbiome status only in control soil with exception of oligotrophs for which soil pH was determinative. PH is not a microbial determinant in natural soils beyond the mentioned exception. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to explore the suitable straw returning methods for grain production in the Zitong River Basin. [Method] The impacts of straw non-returning (BR), straw mulching (FR), straw burying (MR) and straw heap back to field (DR) on soil fertility and grain production were investigated. [Result] Total nitrogen, available phosphorous and organic matter contents treated with FR, MR and DR increased by 18. 6 -38. 2 mg/kg, 5. 6 - 6 . 5 mg/kg, 0. 6 -2. 3 g/kg compared to BR treatment, respectively. The yield of rice, wheat, reap and corn increased by (1. 1 - 1. 3) x 10³, (0. 7 - 0. 8) x 10³, (0. 3 - 0. 5) x 10³, (0. 7 - 1. 0) x 10³ kg/hm², respectively. Returning straw to the field has significant effects on soil nutrients and grain yield. The contents of total nitrogen, available phosphorous and organic matter in DR treatment were significantly higher than FR and MR treatment, and the yield was slightly higher than FR and MR treatment. Rice, rape and corn all achieved the greatest economic benefits under DR treatment, with an average increase of 15. 6%, 27. 2%, 32. 1% compared with FR and MR, respectively. That of wheat on FR and FR was the same, 26. 7% higher than MR treatment. [Conclusion] Comprehensive analysis of the effect of soil fertility in the cultivated, grain yield and economic benefits, heap back to field is more conducive to the fertilization and grain production of the rice, rape and corn fields in the Zitong River Basin, and the straw mulching and heap back to field are both beneficial to the small grain production in the wheat field. [ABSTRACT FROM AUTHOR]

Pulping of rice straw was studied using mild nitric acid in mild conditions. Spent nitric acid was chosen as soil nutrient rather than followed by the liquor recovery. The rice straw was treated with 11.03% nitric acid at 90 °C for 3 h, yielded 53.09% pulp. Nitric acid treated rice straw pulp had high residual lignin and minerals. However, further treatment with 7% potassium hydroxide reduced the residual lignin and produced pulp with kappa number 20.36. The papermaking properties of the nitric acid followed by KOH treated pulp showed better quality than the nitric acid pulp. The spent nitric acid liquor was reused repeatedly, pulp yield decreased and residual lignin content increased in each step of spent nitric acid reusing. The spent nitric acid liquor and potassium hydroxide liquor-mixed together to get a neutral effluent liquor which was rich with potassium, nitrogen and biomass. The nutritional capacity of the effluent liquor was assessed by incubation with control soil. The labile form of organic carbon, nitrogen, potassium phosphorous and iron increased in the incubated soil. [ABSTRACT FROM AUTHOR]

The present paper aimed to explore the expansion mechanism of Elsholtzia densa Benth., a common weed species of degraded alpine meadow and farmland ecosystem in Qinghai-Tibet Plateau. [ Method ] The community characteristics of E. densa invading patches and control patches were investigated, and the Miseq high-throughput sequencing technology combined with soil nutrient and extracellular enzyme activity determination was adopted. [ Result] The changes of community coverage and plant diversity index of E. densa invaded patches were not significant, but the total biomass decreased and leguminous plants were excluded. A total of 33 bacteria were detected from the tested soil, including 30 from rhizosphere soil and 27 from non-rhizosphere soil. Shannon-winner index, Simpson index and Chaol index are respectively 9. 22, 0. 99 and 3024. 91 in rhizosphere soil and 9. 09, 0. 99 and 2707 . 58 in non-rhizosphere soil. Actinobacteria, Proteobacteria, Bacteroidetes, Firmicutes, Acidobacteria and Gemmatimonadetes are the dominant phylum of soil bacteria. Among them, the rhizosphere soil has the highest proportion of Proteobacteria, while the non-rhizosphere soil has the highest proportion of Actinobacteria. Compared with non-rhizosphere soil, the contents of organic matter, total phosphorus, total potassium, total nitrogen, available phosphorus and available nitrogen increased significantly ( P~O. OS ), but the available potassium decreased significantly ( P~O. OS). Among them, available phosphorus increased the most, which was 6. 88 times that of non-rhizosphere soil, followed by organic matter and total nitrogen conltent. The activities of urease, sucrase, cellulase and polyphenol oxidase increased significantly ( P ~ 0. OS ), while the changes of acid phosphatase were not significant. [ Conclusion] Changing soil characteristics and bacterial diversity is one of the mechanisms of E. densa expansion. [ABSTRACT FROM AUTHOR]

A good understanding of the distribution characteristics of soil nutrients is important to achieve the best management of soil nutrients. Kenli County, a typical delta area in Shandong Province in North China, was chosen as the study area of this paper. There were 1 278 soil samples (0- 20 cm) collected, processed and analyzed in laboratory. Geostatistical analysis was conducted to elucidate the spatial variations of soil nutrients and interpolate key soil nutrients in space. The semivariogram models of alkali- hydrolyzable nitrogen (AN), available phosphorus (AP) and available potassium (AK) were estimated. The best fitting models were selected based on the residual sum of squares (RSS) and coefficient of determination (R2). The R2 of AP’s spherical model was 0.951, followed by R2 of AN’s exponential model (0.892) and R2 of AK’s spherical model (0.787). The interpolations were employed with Ordinary Kriging (OK), Inverse Distance Weighted (IDW)，Universal Kriging (UK)，Radial Basis Function (RBF) and Local Polynomial (LP) in GIS software. The prediction accuracy was validated with test data. In order to explore the self-adaptive ability of OK, IDW, RBF and LP, eight datasets with different spatial distribution patterns were designed with AN data. The default optimized model of each method was used on the eight datasets and the results were compared. It comes to the following conclusions: 1) The spatial variations and autocorrelation of AN, AP and AK in the study area are moderate. The best fitted semivariogram models are spherical model, exponential model and spherical model, whose coefficients of determination were 0.951, 0.892 and 0.787, respectively. 2) The spatial distribution patterns of AN, AP and AK are closely related to the terrain and land use types in the study area, i.e., the contents of key soil nutrients are high in the southwest part of region where there are irrigated land and dry land and northeast part of the region where the cropland is along the Yellow River and affected by the freshwater of the river, and the nutrient contents are lower in the central region where there is paddy field. 3) Compared with Nugget/sill, Moran’s I, the most widely used index to describe spatial autocorrelation, is more robust and effective for measuring spatial autocorrelation of soil nutrients. 4) The influence factors of spatial interpolation are spatial distribution pattern, sample number, spatial autocorrelation and spatial clustered degree (measured with Nearest Neighbor Rate); in dispersed pattern, all methods perform bad; in random pattern, IDW and RBF perform better than OK and LP; in clustered pattern, the adaptabilities of the methods are related with sample number and spatial autocorrelation, and all methods perform almost the same when there are enough samples. This paper ascertained the best interpolation prediction method for the main soil nutrients in the study area, analyzed the variation and the spatial distribution of soil nutrients, and provided a theoretical basis for soil nutrients management and agricultural sustainable development in typical area of Yellow River Delta. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to under stand the status of soil nutrient abundance and deficiency in Honghe tobacco-growing area. [Method] 881 tobacco-growing soil samples were collected from different counties (cities) in Honghe tobacco-growing area, and 6 soil nutrient indicators were determined and analyzed. [ Result] The results showed that the average pH value of tobacco-growing soils in 7 counties( cities) was within the suitable growth range of flue-cured tobacco (5. 5 -7. 0), except Shiping county, which was slightly lower. Except for Jianshui ( 23, 66 g/kg) county and Luxi county ( 24. 93g/kg), the average content of organic matter in tobacco-growing soils in other counties( cities) was higher than that in suitable tobacco-growing aoils ( 1S -25 g/kg). The highest proportion of low content of alkali-hydrolyzed nitrogen (AN < 100 mg/kg) was Jianshui county (52. 63 % ), the highest proportion of available phosphorus ( >40 mg/kg) was Shiping county ( 37. 95 % ), the lowest proportion of available phosphorus ( < 20 mg/kg) was Gejiu city ( 90. 47 % ), the highest proportion of excessive water-soluble chlorine ( > 45 mg/kg) was Jianshui county ( 6. 57 % ) . [ Conclusion] The soil nutrient fertility in Honghe tobacco growing area belongs to the middle and upper level, which was more suitable for flue-cured tobacco cultivation. It is suggested that tobacco- growing counties( cities) with slightly poor soil suitability should adjust the existing fertilization schemes according to tobacco leaf quality in order to improve soil nutrient status and tobacco leaf quality. [ABSTRACT FROM AUTHOR]

【Objective】Through the comparison of models, the present paper aimed to explore the influence of ’chninese milk vent Returning to the Field coupled with rice and fish symbiosis’ on the soil nutrients and yield of rice, and provided a scientific basis for efficient and high-quality rice production and sustainable development.【Method】In this experiment, four treatments including conventional rice planting as a control(CK), chninese milk vent Returning to the Field(ZD), rice and fish symbiosis(YD),chninese milk vent Returning to the Field coupled with rice and fish symbiosis(ZY), measuring, analysis and comparison of the contents of soil nutrients(organic matter,total nitrogen, total phosphorus,total potassium and their effective state), rice yield and yield component index of each treatment were performed.【Result】Compared with CK, YD, ZD and ZY can effectively improve the soil fertility of rice in the current season, and ZY has the best effect. Compared with CK, soil organic matter, total nitrogen, total phosphorus, total potassium and their effective state content of ZY mature period were increased by 16.40 %, 18.18 %, 20.63 %, 3.42 %, 7.71 %, 15.96 % and 1.85 %(P<0.05); ZD can effectively alleviate soil acidification, and the soil pH at maturity was 6.06,which compared with CK, YD and ZY, it increased by 0.04, 0.12 and 0.08 units, and the difference was significant(P <0.05);Compared with CK,ZY, ZD, and YD can increase the yield of rice in the season effectively, and ZY has the highest yield of rice, reaching 6.29 t/hm~2. Compared with CK, ZD and YD, the actual yield of ZY increased by 4.83 %-11.33 %,and the difference was significant(P <0.05).【Conclusion】In summary, chinese milk vent returning to the field coupled with rice and fish symbiosis can effectively improve soil fertility and significantly increase rice production in the current season, which was an greenand efficient way of fertilizing. [ABSTRACT FROM AUTHOR]

【Objective】The objective of the paper is to provide a reference for soil nutrient management and sustainable operation in Karst areas.【Method】The soil samples were collected from woodland and dry land in Baiduo Village(dolomite areas) and Shiqiao Village(limestone areas) in Shibing County,Guizhou Province,and then the soil nutrient was analyzed.【Result】The soil developed from dolomite was featured with higher organic matters,total N,available P,available K and hydrolysable N.The soil developed from limestone was featured with higher total P and total K.Total N was positively and very significantly related to hydrolysable N and organic carbon in soil developed from limestone and dolomite.Hydrolysable N was positively and significantly related to organic carbon in limestone areas.Hydrolysable N was positively and very significantly related to organic carbon in dolomite areas.Land use patterns had obvious effects on nutrient content in soil developed from limestone and dolomite.Soil total K,total N,hydrolysable N and organic carbon content in limestone woodland was higher than dry land,and available K,total P,available P and pH was lower than dry land.Soil total P and available P in dolomite woodland are lower than dry land,and other indexes are higher than dry land.The organic matter,total N,total P and total K content in dolomite-developed soil was Grade II,Grade I,Grade VI and Grade III respectively.The organic matter,total N,total P and total K content in limestone-developed soil was Grade II,Grade I,Grade V and Grade I separately.【Conclusion】Soil nutrient was not only affected by soil forming rock,but also affected by land use pattern. [ABSTRACT FROM AUTHOR]

【Objective】 The present paper aimed to find out the soil nutrients characteristics of spatial distribution in the roots of Haloxylon ammodendron in the southern margin of the Gurbantunggut Desert.【Method】The 149-Regimen,Ganjiahu Nature Reserve and the H.ammodendron in the desert area around the Karamay Agricultural Technology Development Zone were taken as examples,The spatial distribution and characteristics of pH,electrical conductivity,water content,organic matter and available phosphorus in the roots of H.ammodendron were quantitatively studied by a combination of field survey sampling and laboratory test analysis.【Result】In different areas,the soil water content and soil pH of the root ofH.ammodendron were mainly near the main root the middle of the crown>the edge of the crown,and the difference was significant(P <0.05); The organic matter content decreased with the depth of the soil layer; The soil available phosphorus content and the soil electrical conductivity were generally in the middle of the crown > near the main root > the crown edge,which generally decreases with the increase of soil depth.【Conclusion】There was a ‘fat island’ effect in the root zone of H.ammodendron in different regions,and the maximum concentration range in 0-40 cm soil layer. [ABSTRACT FROM AUTHOR]

Studying the spatial variability and its affecting factors of surface soil organic matter and total nutrients can provide reference for soil management in the ecological fragile zone of the Loess Plateau. Based on the 93 soil sampling points in Wangdonggou watershed, this paper used a variety of geostatistical methods to analyze the spatial variability and its influencing factors of soil nutrients in the gully region of the Loess Plateau. The results showed that soil nutrient contents in the study area were at a moderate level. The spatial variability was in the following order: Total phosphorus > total nitrogen > organic matter > total potassium, and they were dominated by structural factors. Compared with total phosphorus and total potassium, organic matter and total nitrogen had smaller variation scale, weaker spatial autocorrelation and higher spatial complexity. Soil organic matter and total nitrogen presented a distribution pattern of high in the south and low in the north, and their main influencing factors included elevation, slope, curvature and land use. Total phosphorus was opposite to the former two, namely high in the north and low in the south. Elevation, slope, land use, soil mechanical composition and human activity had great influence on it. Total potassium was high in the center and low in the periphery, and its distribution was relatively scattered, and aspect and soil mechanical composition had a stronger effect on it. In view of the above results, regression prediction models between nine environmental factors and soil nutrients were established to provide data support for the sustainable use of soil resources in the study area. [ABSTRACT FROM AUTHOR]

Brazilian sugarcane production is converting from the traditional manual slash-and-burn to mechanized green cane harvest. The resulting sugarcane trash is mostly left on the field and plowed under at the end of a growth cycle, but it could also be recovered and used to increase the energy efficiency of ethanol. In this paper, we explore in a simulation study if straw recovery negatively impacts yields, fertilizer use, nutrient cycling, GHG emissions, and erosion; if there is an optimal recovery rate; and if different recovery rates are advisable for different soil types. We also compare the traditional slash-and-burn management to the green cane management system. Our results show that when performing straw recovery, trade-offs between different factors such as up to 1.3 t/ha lower yields or an up to 30 kg/ha higher demand for fertilizer N under low recovery rates, and higher erosion rates under high recovery rates have to be accepted. Most balanced would be a recovery rate of 40–60%, but the rate should also be adapted to soil type, with less recovery e.g. on soils prone to erosion, and to economic considerations. A comparison between green cane harvest without straw recovery and the traditional slash-and-burn method shows lower erosion rates and higher soil organic carbon contents, but also a higher fertilizer consumption due to nitrogen immobilization on areas under green cane management. Due to these trade-offs, one method cannot be unequivocally commended over the other. [ABSTRACT FROM AUTHOR]

This paper studies and discusses the changes of soil chemical indexes in different recovery years of XingJ an larch forest in Daxinganling, Inner Mongolia, in order to evaluate the self recovery of natural forest and provide basis for the management of Daxin- ganling forest in Inner Mongolia. The pH, C content, whole nitrogen, whole phosphorus and whole potassium content of the soil used in the experiment were calculated according to the Forest Soil Experiment Tutorial and the Soil Agroization Analysis. The effects of logging interference on the chemical properties of soil were studied using a single - factor variance ( ANOVA) analysis ( SPPS 13. 0 software). Results showed that ： ® comparing the differences in soil pH, soil C and other nutrients in Xing * an larch natural forest and two differ¬ent interference plots of clear cut and gradual cut, it is found that clear cut and gradual cut have significant differences in soil chemical properties (P<0.05). Clear cut has an extreme significant positive correlation with soil total nitrogen (P<0.01) , and a significant positive correlation with soil carbon content and pH ( P < 0. 05 ). (2) Comparing the significance of different cutting methods on soil physical and chemical properties in different years, there is a certain gap between the logging sites in 1987 and 2014, while the differ¬ences between the logging sites in 2009, 1987 and 2014 are not significant. Conclusion ： deforestation interference can reduce the pH of soil, objectively increase soil nutrients, and may be conducive to the natural renewal of forests. Logging interference significantly af¬fects the balance of soil carbon and other nutrients [ABSTRACT FROM AUTHOR]

In Egypt all agricultural practices are generally applied uniformly without taking spatial variability into consideration, which is not efficient and may be more expensive than site-specific management approach. This is based on accurate assessment of within-field variation and on field delineation into homogeneous zones to be submitted to differential management. Multivariate geostatistics allows to assess and model the spatial variation of a set of soil attributes influencing management. The objective of this paper was to propose an approach for determining spatially variable rate application (VRA) of leaching water, to control soil salinity, and of fertilizer to improve productivity while reducing environmental impact. The research was conducted in an experimental 3.1-ha field in Egypt and the following soil attributes were measured: electrical conductivity (ECe), available nitrogen (N), available phosphorus (P), available potassium (K) and organic matter content (OM). Ordinary cokriging was applied to produce thematic maps of soil attributes and the appropriateness of the linear model of coregionalization was evaluated with cross-validation. Spatial maps of the five soil variables were classified into three isofrequencies classes and the mean values were calculated for each class. These values were then compared with critical reference values to assess the local soil requirements for reducing soil salinity and/or improving soil fertility. The results showed that the estimations of soil attributes were unbiased and accurate. Only for ECe and available nitrogen site-specific management would be preferable because it would reduce the agricultural costs for both soil reclamation (saving water used to leach salts) and improvement of soil N fertility in comparison with the traditional uniform methods. The proposed approach, though producing encouraging results, would require improvements in the determination of the threshold values used to plan salt leaching and soil fertilization. Unlabelled Image • Accurate spatial variability assessment is essential for site-specific management. • Multivariate geostatistics provided accurate estimation of soil spatial variability. • Variable rate leaching was cost effective compared to traditional approach. • Variable rate nitrogen application was more expensive than the conventional fertilization. • Spatial soil maps are needed in agronomic experimental design. [ABSTRACT FROM AUTHOR]

• Obtaining soil reflectance spectral data with a spectral photometer. • Acquiring a series of alternative bands by correlation analysis. • Extracting characteristic bands of SOM, TN, AK and AP by weight analysis based on AHP. • Revising AHP judgment matrix with PSO algorithm for optimization. • BPNN inversion models outperform SVM and PLS in predicting TN, SOM, AP, and AK. The selection of characteristic bands of soil nutrients is crucial for the prediction of soil nutrient contents. In this paper, a measurement method based on the analytic hierarchy process (AHP) and reflectance spectrum is proposed to realize the extraction of characteristic bands and the prediction of soil nutrients. Firstly, a series of alternative bands are obtained by mathematical transformations and correlation analysis from the reflectance spectral curves of 30 soil samples. Then, to objectively reflect different dependencies of spectral bands on the soil nutrients, AHP is adopted for weight analysis, and the particle swarm optimization algorithm (PSO) algorithm is used to correct the expert scoring matrix. Via the weight allocation, weight normalization and weight threshold, the alternative bands meeting the sum threshold of weights > 0.5 are finally selected as the characteristic bands of soil nutrients, which are at 484 nm, 512 nm, and 760 nm for total nitrogen (TN), and at 384 nm, 736 nm, and 748 nm for available phosphorus (AP). Finally, three inversion models established by the characteristic bands are used to predict soil nutrient contents, which demonstrated the feasibility of the analytic hierarchy process for the extraction of characteristic bands and the prediction of soil nutrients. [ABSTRACT FROM AUTHOR]

Summary: Censuses of tropical forest plots reveal large variation in biomass and plant composition. This paper evaluates whether such variation can emerge solely from realistic variation in a set of commonly measured soil chemical and physical properties.Controlled simulations were performed using a mechanistic model that includes forest dynamics, microbe‐mediated biogeochemistry, and competition for nitrogen and phosphorus. Observations from 18 forest inventory plots in Guanacaste, Costa Rica were used to determine realistic variation in soil properties.In simulations of secondary succession, the across‐plot range in plant biomass reached 30% of the mean and was attributable primarily to nutrient limitation and secondarily to soil texture differences that affected water availability. The contributions of different plant functional types to total biomass varied widely across plots and depended on soil nutrient status. In Central America, soil‐induced variation in plant biomass increased with mean annual precipitation because of changes in nutrient limitation.In Central America, large variation in plant biomass and ecosystem composition arises mechanistically from realistic variation in soil properties. The degree of biomass and compositional variation is climate sensitive. In general, model predictions can be improved through better representation of soil nutrient processes, including their spatial variation. [ABSTRACT FROM AUTHOR]

[Objective]This paper aimed to grasp the difference of soil nutrient content among die ancient lea gardens in Menghai county and provide a scientific basis for their soil nutrient management, which will help the county § tea production to achieve high-efficiency, high-quality and ecological goals. [Method] A total of 9 representative ancient lea gardens in Menghai county were selected for soil sampling, and the results were analyzed comprehensively. [Result] The pH value of 66.7% of the ancient tea gardens soil was 4.5 -5.5, and 33.3 % was lower than 4.5; the organic matter content of 22.2% of the ancient lea gardens was higher than 30 g/kg, and 77.8 % was between 10 g/kg and 30 g/kg; all the alkali-hydrolyzed nitrogen content exceeded 120 mg/kg; the available phosphorus content of 88.9 % of the ancient tea gardens was less than 3 mg/kg; the available potassium content of 66.7% of the ancient tea gardens was less than 50 mg/kg. [Conclusion] In the soil of the ancient lea gardens, the pH value of some tea plantations was lower than 4.5; the contents of organic matter and alkali-hydrolyzed nitrogen were relatively rich; the contents of available phosphorus and available potassium were relatively deficient. We should give full play to all kinds of organic fertilizer resources, increase the soil fertility of ancient lea gardens, use good soil testing and formula fertilization technology, improve the soil nutrient structure and pH value of ancient tea gardens, and ensure that there are reasonable and efficient soil nutrient banks in ancient lea gardens. [ABSTRACT FROM AUTHOR]

[Objective]The aim of this paper was to explore the distribution characteristics of soil nutrients in different recovery modes of rocky desertification control, and to provide scientific basis for further optimizing the vegetation allocation of rocky desertification control. [Method] Taking soil from five sampling sites as the study object, including Zanthoxylum bungeanum, Lonicera japonica, mixed forests, cardamom and abandoned farmland in Huajiang Rocky Desertification Control Demonstration Area in Guizhou. Soil layers of 0 - 10, 10 -20 and 20 -30 cm were sampled and monitored for 3 years before, during and after rainy season, and the distribution characteristics of soil nutrients under different recovery modes were analyzed. [Result] With the restoration of vegetation, compared with abandoned farmland, average values of soil bulk density, soil retention ability and capillary porosity in the four plots decreased respectively by 0.61 %, 7.97 % and 1.12 % , soil organic carbon, total nitrogen, total phosphorus and total potassium increased by 53.45 %, 45.72 %, 80.81 % and 1.44 % respectively, hydrolyzed nitrogen and available phosphorus increased by 53.36 % and 25.80 % , respectively. In the same plot, the contents of soil organic matter and soil nutrient contents were all shown as during rainy season > after rainy season > before rainy season. With the increase of depth of the soil layer, content of soil nutrients of different recovery models decreased, nutrients mainly concentrated in the surface layer. [Conclusion] There were differences in nutrient contents between different restoration models, and vegetation restoration in karst rocky desertification area had an ameliorative effect on ecological environment. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to understand the fertility status of different types of tobacco planting soils in Honghe Prefecture. [Method] 888 soil samples were collected from different types of tobacco planting soils in Honghe Prefecture. [Result] The results showed that the average pH of the six types of soils except yellow soil was slightly lower, the of soil pH other types was all within the suitable growth range of flue-cured tobacco; the average content of organic matter except clay soil was higher than that of suitable organic matter content; the highest average content of alkali-hydrolyzed nitrogen was yellow soil, which reached 162.67 mg/kg. The average content of alkali-hydrolyzed nitrogen was the lowest in clay soil (106.37 mg/kg); the average content of available phosphorus was at middle level except yellow soil, the highest was sandy loam soil (39.60 mg/kg); the lowest was red soil (23.03 mg/kg); The average content of available potassium was the highest in red soil (230.50 mg/kg); the other types of soil was at the middle level, and the lowest in yellow soil (160.89 mg/kg). The content of water-soluble chlorine was highest in yellow soil, and the lowest in clay soil. Available zinc content of six types soils could meet the needs of high-quality flue-cured tobacco production, available boron content was lower than the critical value, available molybdenum content was higher than the critical value, but the proportion of available molybdenum content in other five types of soils was higher than the critical value except yellow soil. [Conclusion] Overall, alkaline fertilizer should be applied to improve the acidic yellow soil in Honghe tobacco-growing area, organic matter and alkaline hydrolyzable nitrogen content in clay soil was low, organic fertilizer and nitrogen fertilizer should be supplemented, chlorine-containing fertilizer should be forbidden in yellow soil with high water-soluble chlorine content, and available boron and molybdenum in six types of soils was generally low, so which should be increased. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to study the soil nutrients and soil microbial activity of different tillage system in orchard. [Method] Field control experiment and laboratory analysis were conducted to study soil nutrients and microbial activities under different tillage system. [Result] Under different tillage system, soil pH was slightly acidic, and opposite volume weight, which showed no tillage > ploughed tillage > rotary tillage; Soil fertility (soil organic matter and total nitrogen) and available nutrients (available phosphorus, available nitrogen and available potassium) of different tillage system had the same variation trend which showed rotary tillage > ploughed tillage > no tillage, while there was no significantly difference of different tillage system in soil total phosphorus (P>0.05) ; Compared with no tillage, there was a significant increase in soil total microbial quantity and soil enzyme activity (invertase, dehydrogenase, urease and phosphatase), which ordered rotary tillage > ploughed tillage > no tillage under rotary tillage and ploughed tillage. Soil microbial activity was from 0. 38 to 0. 69 in order of rotary tillage > ploughed tillage > no tillage with the significant difference (P <0.05). [Conclusion] Overall, the soil microbial biomass carbon turnover rate was higher than the soil microbial biomass nitrogen turnover, which indicated that the microbial biomass carbon updated faster than microbial biomass nitrogen. [ABSTRACT FROM AUTHOR]

Little is known about how soil properties control tree growth at its upper limit. This paper reviews the state of knowledge and discusses the results specifically related to ecozones, to the scale-dependent importance of single factors, and to new findings from a near-natural treeline ecotone in Rolwaling Himal, Nepal. This paper identifies gaps in literature and shows where new research is needed, both conceptual and geographical. The review shows that at a global scale and throughout diverse ecozones, growing season soil temperature is considered a key factor for tree growth. Soil temperatures differ greatly at a local scale, and are mainly determined by local climatic, edaphic, and topographic conditions. Our result of 7.6 ± 0.6°C for growing season mean soil temperature at treeline in Rolwaling is 1.2 K higher compared to the postulated 6.4 ± 0.7°C for alpine treelines. We suggest a broadening of the ±0.7°C error term to cover the wide range at a local scale. The role of major soil nutrients and soil moisture for treeline shift has been underestimated by far. In Rolwaling, significantly decreasing nutrient availability (N, K, Mg) in soils and foliage with elevation might explain why treeline shift and global warming are decoupled. Further, soil moisture deficits early in the year impede seedling and sapling establishment, which could be an important mechanism that controls treeline position. These findings question previous results which argue that alpine treelines are unaffected by soil nutrient availability and soil moisture. We assume that specific combinations of soil properties as well as single soil properties limit tree growth even below climatic treelines. [ABSTRACT FROM AUTHOR]

【Objective】 The present paper aimed at analyzing the characteristic of soil cycle and root distribution covering with the Stylosanthes. 【Method】In 2008, the complex ecosystem with covering the Stylosanthes in rubber plantation was established, and in 2014, the soil samples and the root system in the tested area were investigated and analyzed. 【Result】 The covering Stylosanthes in rubber plantation respectively increased the soil organic matter of 46% from 0 to 10 cm soil and 17% from 10 to 20 cm soil, reaching significant level, and the total nitrogen content, the activity of invertase, urease and acid phosphatase were also increased, promoting the growth of root system. Dry weight and fresh weight respectively increased 98.07% and 77.11%, the root distribution was transformed mainly from 10-20 cm to mainly 0-10 cm, the content of root hydraulic was higher than 50%, the amount of fine root was increased, and lignification degree was declined. 【Conclusion】Covering stylosanthes in rubber plantation, the ripen degree of surface soil was increased, the transformation and utilization of nutrition was promoted, the root distribution of rubber tree was controlled, the activity of root system was increased and the absorption and utilization of soil nutrient was promoted. [ABSTRACT FROM AUTHOR]

In order to evaluate the effects of different levels of water and fertilizer on yield and quality of jujube under drip irrigation that changed from flooding, a field experiment was conducted to find the optimal irrigation and fertilizer combination with the higher water and fertilizer use efficiency. The statistical analysis methods of multivariate quadratic regression and normalization were used in this paper. The local jujube variety of Jun-jujube(9 years) was chosen for test material. The conventional flooding irrigation with irrigation and fertilizer quota as 1100 mm and 900 kg/hm2 (N:P:K = 2:1:1.5) respectively was selected as the control group (CK). In this study, the irrigation and fertilizer treatments were designed with a two-factor and three-level quadratic orthogonal rotated composite experiment. The irrigation amount treatments in three levels was W1 (45% CK), W2 (65% CK), W3 (85% CK), and fertilizer treatments in three levels was F1 (45% CK), F2 (65% CK), F3 (85% CK), respectively. The results showed that the effects of irrigation on soil nutrients (total N, available P, available K) and irrigation water use efficiency (iWUE) reached significant level (P < 0.05) in the jujube growth period of flowering and swelling. The effects of fertilization on soil nutrient and fertilizer partial productivity (PFP) reached significant level (P < 0.05) in the period of jujube flowering and swelling. However, the interaction effects of irrigation and fertilization on soil nutrients, yield and jujube quality indicators reached significant level (P < 0.05) at the whole stages of growth. The soil nutrients in 0-40 cm layer were higher under flooding irrigation than that under drip irrigation. There was a nutrient transition layer at depth of 40~60 cm. while the soil nutrients were significantly lower under flooding irrigation than that of drip irrigation in the soil layer of 60-100 cm. The W2F3 treatment had the better soil nutrient environment in the root zone for the different irrigation and fertilizer treatments. Comparing with flooding irrigation, the maximum soil nutrients value under the drip irrigation were W2F3 treatment generally. The drip irrigation treatment of W2F3 had the highest yield, but there was no significant difference with CK (P > 0.05). The maximum value of iWUE and PFP was W1F3 and W3F1 treatment, respectively. The maximum value of total sugar, vitamin C and total acid was in W2F2, W3F3 and W3F1 treatment, respectively. W3F2 treatment and CK had significant difference (P < 0.05) in the net income, and increased by 1.95% comparing with the CK. The mathematic model of water-fertilizer investment and jujube indicators was established through multiple quadratic regression analysis, and the suitable investment of water and fertilizer obtained from the mathematic model were ranged in 651~806 mm and 708~806 kg/hm2, respectively, where N (311-345 kg/hm2), P2O5 (156-178 kg/hm2), K2O (233-267 kg/hm2). The study can provide a reference for the optimal irrigation and fertilization management of jujube cultivation in the southern Xinjiang sandy area with drip irrigation. [ABSTRACT FROM AUTHOR]

【Objective】 The present paper aims to reveal the characteristics of nutrient quality among different land use patterns, and to provide scientific references for land productivity restoration, soil science research and agricultural sustainable development.【Method】 The authors took Zanthoxylum bugeanum, Lonicera japonica, Hylocereus undulatus, Juglans regia, Tectona and Zea mays fields as the research object in the dry-hot valley rocky desertification region, and employed Pearson correlation analysis and principal component analysis to clarify the changes of soil physical and chemical properties between the six kinds of land use patterns and soil correlation between quality indicators.【Result】 (i) Contents of C and N in the area of Z. bugeanum in dry-hot valley rocky desertification region was low, contents of TP, TK and AK in the soil of J. regia, L. japonica and Z. mays was relatively deficient. The nutrient elements in the soil of the H. undulates and Tectona land were low.(ii) Correlation analysis showed that significant positive correlation was found between TN content and pH, AN content and SOC content, TK/AK content and TP content, TK content and AK content. However, there was extremely significant negative correlation between the soil of BD and TN.(iii) Comprehensive index of soil quality was Z. bugeanum(2. 334) > L. japonica(1.283) > Z. mays (0.330) > J. regia(-0. 386) > Tectona(-1.153) > H. undulates(-1.598). 【Conclusion】 In the process of crop cultivation and management in dry-hot valley rocky desertification region, we should supplement mineral elements such as N, P, K, and pay attention to the synergistic effect of nutrient supply. [ABSTRACT FROM AUTHOR]

Soil losses by water erosion were studied under six different tillage treatments, which differ in depth and direction of tillage and planting during a twenty-year period (1995-2014) on Stagnosols in central lowland Croatia. Studied tillage treatments were: control plot (bare fallow-BF), ploughing up and down the slope to 30 cm (PUDS), notillage (NT), ploughing across the slope to 30 cm (PAS), very deep ploughing across the slope to 50 cm (VDPAS), and subsoiling to 50 cm + ploughing to 30 cm across the slope (SSPAS). The paper presents the following chemical parameters: soil pH, soil organic matter (OM), plant available phosphorus (P-P2O5), plant available potassium (K-K2O), total carbon content (Ctot), total nitrogen content (Ntot) and CN ratio of non-eroded soil and soil loss from studied treatments. All soil sediments had significantly higher content of the studied parameters compared to non-eroded soil. The overall respective levels of OM, Ctot, Ntot, P-P2O5 and K-K2O loss by eroded soil were as follows: 0.86 (NT) - 10.86 (BF) t/ha, 0.10 (SSPAS) - 2.60 (BF) t/ha, 0.015 (SSPAS) - 0.392 (BF) t/ha, 0.012 (NT) - 0.173 (BF) t/ha and 0.017 (SSPAS) - 0.158 (BF) t/ha. No-tillage and treatments with tillage across the slope (PAS, VDPAS, SSPAS) proved to be much more efficient in storing investigated soil nutrients. [ABSTRACT FROM AUTHOR]

Through analyzing the soil organic matters (N, P, K) of farmland cultivated with different years of Panax ginseng, this paper studied the changes in soil nutrients of farmland with different vertical depths and cultivation years of P. ginseng. Results indicated that the vertical structure was obvious in soil nutrients of farmland with different cultivation years of P. ginseng; in most cases, the soil nutrient content gradually declined with the fibrous roots of P. ginseng spreading downward; the soil electrical conductivity (EC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), available nitrogen, available phosphorus were manifested as surface layer > root layer > bottom layer, while the available potassium was manifested as surface soil and bottom layer > root layer; the soil pH changed in the range of 5.69-6.22, suitable for growth of P. ginseng. It is expected to provide theoretical basis for improvement of soil nutrients of farmland with cultivation of P. ginseng. [ABSTRACT FROM AUTHOR]

[Objective ] The present paper aimed to study the spatial variability of soil nutrients under different terrain and topography conditions. [Method ] Classical statistics combined with Geostatistics were applied to analyze the spatial variability of soil nutrients in different terrain and direction of Zhongxiang city. [Result] The coefficient of variation of soil organic matter, available P and available K in different terrain were between 23. 79 % and 69.78 % and belonged to moderate variation; All data were normally distributed after Box-Cox transformation. Soil nutrient content in the hills was higher than that in the plain. The spatial correlation of soil organic matter in plains was greater than that in hills. The spatial correlation of available P in eastern part was greater than that in the western part, but the available K was opposite. The results indicated that the spatial variability of soil nutrients in horizontal and vertical direction variation patterns were not uniform even in the same terrain and river basin, which was caused by both natural environment and human factors. [Conclusion]The spatial variation of soil nutrient in the horizontal and vertical directions was not uniform, especially in the hilly watershed with variable geographical conditions. The spatial variability of nutrients was influenced by natural faetors. [ABSTRACT FROM AUTHOR]

Intercropping as an example of sustainable agricultural systems follows objectives, such as the ecological balance, more exploitation of resources and increase in soil fertility. Evaluation of soil nutrients in intercropping is a basic criterion for selecting the type of cultivation and increasing the productivity of the soil. Based on experimental study, evaluation of soil needs time and cost too much. However the soil parameters can be rapidly estimated using predicted meteorology and can be appropriately assessed. Linear estimation methods are less accurate than non-linear methods, but non-linear methods for modeling of soil elements are difficult due to highly computing times. The artificial intelligence is a powerful tool for fast modeling, more accurately. In this paper, artificial intelligence method such as Artificial Neural Networks (ANN) and Adaptive Neuro-Fuzzy Inference System (ANFIS) has been used to estimate soil chemical properties (carbon and nitrogen). Four input parameters including the soil temperature, type of intercropping (different ratios of Roselle – green gram), type of tillage (no-tillage, minimum tillage, conventional tillage) and sodium have been used in ANN and ANFIS prediction. ANFIS and ANN modeling have been compared using several statistics (root mean square error (RMSE) and Mean Absolute Error (MAE). The results indicate that the artificial intelligences can be successful applied for estimating soil carbon and nitrogen. ANFIS is found to be more accurate than the ANN. A sensitivity analysis has conducted based on ANFIS estimate. It is shown that increased percent of green gram in intercropping can reduce the percentage of carbon to nitrogen (C/N). [ABSTRACT FROM AUTHOR]

Prediction of carbon dynamics in response to global climate change requires an understanding of the processes that govern the distribution of carbon stocks. Above-ground biomass ( AGB) in tropical forests is regulated by variation in soil fertility, climate, species composition and topography at regional scales, but the drivers of fine-scale variation in tropical forest AGB are poorly understood. The factors that control the growth and mortality of individual trees may be obscured by the low resolution of studies at regional scales., In this paper, we evaluated the effects of soil nutrients, topography and liana abundance on the fine-scale spatial distribution of AGB and density of trees for a lowland tropical moist forest in Panama using additive regression models., Areas with larger values of AGB were negatively associated with the presence of lianas, which may reflect competition with lianas and/or the association of lianas with disturbed or open-canopy patches within forests. AGB was positively associated with soils possessing higher pH and K concentrations, reflecting the importance of below-ground resource availability on AGB independently of stem density., Synthesis. Our results shed new light on the factors that influence fine-scale tree AGB and carbon stocks in tropical forests: liana abundance is the strongest predictor, having a negative impact on tree AGB. The availability of soil nutrients was also revealed as an important driver of fine-scale spatial variation in tree AGB. [ABSTRACT FROM AUTHOR]

In this paper, the soil samples of the irrigation areas of farmland of Turpan city's four major rivers( Daheyan river, Tallang river, Mines ditch and Black ditch) were collected, their soil total salt, the salt, the conductivity, main ion content and soil nutrient were measured, and the soil salinization types, degree and the different spaces of soil salinity in every river were comparatively analyzed, their relationship between soil salt content and main ion was determined, and the effects of different irrigation waters on soil nutrient compositions were studied. The results showed that part of the soils in the study areas had the tendency of salinization, and the trend of soil secondary salinization was comparatively higher, which had a close relationship with the soil salinity level of the ions(CO3-, HCO3-, SO42-, Cl-, Ca2+, Mg2+, Na+, K+ ). The spatial distribution of soil salt was different with different terrain. Along the four rivers the main ingredients of irrigated soil salinization types were sulfate saline soils. The Karez irrigation soil nutrient content was better than that of the given priority of river's. [ABSTRACT FROM AUTHOR]

Biochar addition to soil is a promising option for climate change mitigation and is recognized to exert beneficial effects on soil fertility. However, recent meta-analysis documented controversial effects on soil–plant interactions and on crop yields response. The data presented in this paper are the results of a field experiment on a processing tomato crop aiming to enhance the knowledge on the real applicability of biochar at farm scale in a high fertility alkaline soil. The effects of two biochar types on soil properties and on quantitative and qualitative parameters of processing tomato were evaluated. Biochar application significantly increased the soil carbon content, the soil cation exchange capacity and the availability of NH 4 + , P and K. Moreover, it stimulated plant growth and N, P and base cation contents at harvest, reducing the leaf water potential in the warmer period. These results demonstrate that also intensive cultivations in fertile soil can benefit from biochar amendment. [ABSTRACT FROM AUTHOR]

In this paper, six important distribution areas of Nitraria tangutorum Bobr. in Tsaidam Basin were selected as research objects, to study spatial variability and distribution of soil nutrients in different N. tangutorum populations and analyze the relationship between soil nutrient contents and geographical location, by measuring soil pH and the contents of organic matter(OM), total nitrogen(N), total phosphorus (P), total potassium (K), hydrolysis N, available P and available K in soils. Results showed that: (1) soil nutrient contents among different populations showed significant spatial variability, and soil depth had a significant effect on soil nutrients contents, but the variation rules were not obvious. (2)Average pH and average contents of OM, total N, total P, total K, hydrolysis N, available P and available K in soils with different depths (0-15, 15-30, 30-45 cm) varied in the range of 8.37-9.21, 3.34- 20.68, 0.18-1.21, 0.35-0.75, 16.12-22.04, 5.13-553.28, 1.10-52.54 and 103.83- 562.28 mg/kg, respectively. (3) The analysis results of correlation between average values of pH and contents of nutrient indexes in soils with different depths (0-15, 15-30, 30-45 cm) showed that the correlation of these indexes were different. (4) OM and total N contents in soils with different depths (0-15, 15-30, 30-45 cm) all had a significant positive correlation with latitude and negative correlation with longitude and altitude, and the correlation of available P and available K contents in surface soils (0-15 cm) with latitude, longitude and altitude were significant positive, significant negative and significant negative, respectively; moreover, longitude and latitude also showed a significant impact on soil available K contents with the depth of 30-45 cm. In addition, comprehensive analysis result of nutrient contents showed that N. tangutorum populations in Huaitou Tala Town had the highest fertility, and the fertility levels of N. tangutorum populations in Chaka Town and Wulan Keke Town were relatively lower. [ABSTRACT FROM AUTHOR]

Soil nutrient is the basis for stable and high crop yield. Mastering soil's nutrient content of cultivated land is the precondition for　implementing soil test and formula fertilization. Investigations of soil's pH value and nutrient of vegetable land, paddy field and fruit land in Guizhou Anshun area were carried out in this paper. The results showed that soil's pH value of cultivated land in Guizhou Anshun area was lower than 7, and the soil was overall acidic; soil nutrient was sufficient, the organic matter, total nitrogen, total phosphorus and total kalium content were in the middle and upper level, but there were significant differences among different districts. The pH value was 5.75 on average and the range of measurement was 4.65-6.2; the value of organic matter on average was 31.13g/kg and the range of measurement was 13.07-94.55g/kg; the value of total nitrogen was 1.74g/kg on average and the range of measurement was 0.73-3.97g/kg; the total phosphorus value was 0.998g/kg on average and the range of measurement was 0.44-1.91g/kg; potassium value was 16.5g/kg on average and the range of measurement was 2.5-42.5g/kg. The soil's pH value for Guanling > Pingba > Puding > Ziyun > Zhenning ≥ Xixiu, the content of organic matter for Xixiu > Puding > Guanling > Ziyun > Pingba > Zhenning, the content of total nitrogen for Xixiu > Guanling > Ziyun > Puding > Pingba > Zhenning, the content of total phosphorus Puding > Guanling > Zhenning > Pingba > Ziyun > Xixiu, the content of total kalium for Puding > Pingba > Zhenning > Guanling > Xixiu > Ziyun. The difference of nutrients in different soil types was significant. The main nutrient content was highest in paddy soil, lowest in fruit land，and vegetable soil's nutrient was in between. There was a significant difference with the same soil type and the same nutrient content. The difference was the largest in organic content and was small in other nutrients. Therefore, this investigation has basically mastered the cultivated land soil's pH value and organic matter, total nitrogen, total phosphorus and total kalium content and distribution in Anshun, which can provide the decision-making reference for soil test and formula fertilization in regional land. [ABSTRACT FROM AUTHOR]

• An improved GA is presented for nutrient recommendation in time-series sensor data. • An exploration is used to speed evolution process and increase convergence rate. • An exploitation is used to optimize the parameters for achieving maximum yield. In agricultural production, soil characteristics play a vital role in maintaining fertility by allowing crops to develop better through root nutrition with minimal energy inputs. Nitrogen (N), Phosphorus (P), and Potassium (K) are all important nitrogen fertilizers extensively utilized in crops to supply a sufficient level of nutrients and keep their production level high. However, the application is generally limited to specific crops because of the global variability in these essential nutrients. Stability in fertilizer application, growth, and root growth rate increases crop fertility and crop production. To predict the suitable nutrients for different crops and provide nutrients recommendations by analyzing the crop fertility and yield production, this paper proposes nutrient recommendations through an improved genetic algorithm (IGA) that uses time-series sensor data and recommends various crop settings. A neighborhood-based strategy is then presented to handle exploration and exploitation for optimizing the parameters to obtain the maximum yield. The method can expand knowledge by using the population exploration strategy. The final recommendation is made by using the similarity between recommended patterns and real-time sensor data. With time, crop fertility decreases due to the low level of nutrients. This crop model will help to increase yield by analysis of the seasonal fertility performance of the soil. The proposed method is also a useful tool to improve soil fertility performance by providing the nutrient recommendation of optimal conditions for crop development. Experimental results show that the proposed model can recommend optimizing patterns and increasing the yearly yield efficiently. The method can help identify the region to assess crop suitability under certain nutrients levels and give insight into nutrient suitability assessments concerning specific crops in a climate-changing world. [ABSTRACT FROM AUTHOR]

The excessive use of chemical fertilizers can lead to severe environmental damages. In recent decades, the application of biostimulants to improve soil composition and stimulate plant growth has contributed significantly to environmental preservation. In this paper, we studied the effect of a rhizogenic biostimulant, obtained from fulvic acids, probiotics, and prebiotics, on the fertility of two types of soils, sandy and sandy loam soils, in which turfgrass was growing. Soil samples from plots treated with biostimulant and controls (untreated plots) were collected. The analyzed parameters from the soil include organic matter, microbial activity, soil chemical composition, catalase, dehydrogenase, and phosphatase enzyme activities. Moreover, root lengths was examined and compared in turfgrass species. The biostimulant application improved microbial activity, organic matter, and enzymatic activity in both types of soils. The soil calcium, potassium, magnesium, and phosphorus content increased with the biostimulant application, whereas pH and electrical conductivity decreased. The most relevant improvement was a 77% increase of calcium for sandy loam soil and 38% increase in potassium for sandy soil. Biostimulant application led to a significant increase in turf root length. This increase was greater for sandy soil than in sandy loam soil with an increment of 43% and 34% respectively, compared to control. [ABSTRACT FROM AUTHOR]

The mapping of soil nutrients is a key issue for numerous applications and research fields ranging from global changes to environmental degradation, from sustainable soil management to the precision agriculture concept. The characterization, modeling and mapping of soil properties at diverse spatial and temporal scales are key factors required for different environments. This paper is focused on the use and comparison of soil chemical analyses, Visible near infrared and shortwave infrared VNIR-SWIR spectroscopy, partial least-squares regression (PLSR), Ordinary Kriging (OK), and Landsat-8 operational land imager (OLI) images, to inexpensively analyze and predict the content of different soil nutrients (nitrogen (N), phosphorus (P), and potassium (K)), pH, and soil organic matter (SOM) in arid conditions. To achieve this aim, 100 surface samples of soil were gathered to a depth of 25 cm in the Wadi El-Garawla area (the northwest coast of Egypt) using chemical analyses and reflectance spectroscopy in the wavelength range from 350 to 2500 nm. PLSR was used firstly to model the relationship between the averaged values from the ASD spectroradiometer and the available N, P, and K, pH and SOM contents in soils in order to map the predicted value using Ordinary Kriging (OK) and secondly to retrieve N, P, K, pH, and SOM values from OLI images. Thirty soil samples were selected to verify the validity of the results. The randomly selected samples included the spatial diversity and characteristics of the study area. The prediction of available of N, P, K pH and SOM in soils using VNIR-SWIR spectroscopy showed high performance (where R2 was 0.89, 0.72, 0.91, 0.65, and 0.75, respectively) and quite satisfactory results from Landsat-8 OLI images (correlation R2 values 0.71, 0.68, 0.55, 0.62 and 0.7, respectively). The results showed that about 84% of the soils of Wadi El-Garawla are characterized by low-to-moderate fertility, while about 16% of the area is characterized by high soil fertility. [ABSTRACT FROM AUTHOR]