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With hydroponics culture, we monitored the response of the growth and nutrient accumulation of oilseed rape ( Brassica napus L.) to five ethanol concentrations: 0 mL•L -1 (control), 0.0125 mL•L -1 , 0.025 mL•L -1 , 0.05 mL•L -1 , and 0.25 mL•L -1 , respectively. The results showed that a high concentration of exogenous ethanol (0.25 mL•L -1 ) significantly inhibited oilseed rape growth by 52.28%. However, the biomass of oilseed rape with a low concentration of exogenous ethanol (0.0125-0.05 mL•L -1 ) manipulation was raised by 16.62-44.08%. A similar result was found on the total nitrogen, phosphorus, and potassium of the oilseed rape. Results of micro-element determination showed that iron and zinc accumulation in oilseed rape was unchanged, while manganese and copper accumulation was increased first and then decreased with increasing ethanol concentration. This study provided a possibility for improving plant growth with low concentration ethanol application in oilseed rape planting.

This study aimed to investigate the effects of four types of slow-release fertilizers on the stoichiometric ratio of nitrogen, phosphorus, and potassium and biomass of Fraxinus malacophylla seedlings and to screen for the optimal fertilization amount for seedling growth. Four fertilization rates (0, 1, 2, and 4 kg m³) were employed as treatment for one-year-old F. malacophylla seedlings, with no fertilization (CK) as the control. Biomass, growth, and N, P, and K contents of each organ were measured, and the accumulation of N, P, and K was calculated. Curve fitting was performed to analyze the relationship between N, P, and K accumulation in various organs and stoichiometric ratio and biomass. The results showed that the best nutrient accumulation and biomass of F. malacophylla seedlings were obtained under the dosage of 1 kg m-3 slow-release fertilizer, and significantly higher than those of the control group. The biomass of each organ and the accumulation of N, P, and K was in this order as follows: leaf>root>stem, and the accumulation of nutrients in each organ and single plant was in this order; N>K>P. A highly significant positive correlation (P<0.01) was observed between the accumulation of N, P, and K in various organs and biomass of F. malacophylla seedlings. N: P and K: P negatively correlated with biomass, whereas N: K significantly positively correlated with biomass (P<0.05). The N: P values of all organs of F. malacophylla seedlings were <14; plant growth was limited by elemental N, N: K<2.10, and K P>3.40; and plant growth was not influenced by K. In summary, a dosage of 1 kg m-3 slow-release fertilizer is beneficial for the growth of F. malacophylla seedlings. [ABSTRACT FROM AUTHOR]

In general, remote sensing studies assessing cover crop growth are species nonspecific, use imagery from satellites or modified unmanned aerial vehicles (UAVs), and rely on multispectral vegetation indexes (VIs). However, using RGB imagery and visible-spectrum VIs from commercial off-the-shelf (COTS) UAVs to assess species specific cover crop growth is limited in the current scientific literature. Thus, this study evaluated RGB imagery and visible-spectrum VIs from COTS UAVs for suitability to estimate concentration (%) and content (kg ha−1) based cereal rye (CR) biomass, carbon (C), nitrogen (N), phosphorus (P), potassium (K), and sulfur (S). UAV surveys were conducted at two fields in Indiana and evaluated five visible-spectrum VIs—Visible Atmospherically Resistant Index (VARI), Green Leaf Index (GLI), Modified Green Red Vegetation Index (MGRVI), Red Green Blue Vegetation Index (RGBVI), and Excess of Greenness (ExG). This study utilized simple linear regression (VI only) and stepwise multiple regression (VI with weather and geographic data) to produce individual models for estimating CR biomass, C, N, P, K, and S concentration and content. The goodness-of-fit statistics were generated using repeated K-fold cross-validation to compare individual model performance. In general, the models developed using simple linear regression were inferior to those developed using the multiple stepwise regression method. Furthermore, for models developed using the multiple stepwise regression method all five VIs performed similarly when estimating concentration-based CR variables; however, when estimating content-based CR variables the models developed with GLI, MGRVI, and RGBVI performed similarly explaining 74–81% of the variation in CR data, and outperformed VARI and ExG. However, on an individual field basis, MGRVI consistently outperformed GLI and RGBVI for all CR characteristics. This study demonstrates the potential to utilize COTS UAVs for estimating in-field CR characteristics; however, the models generated in this study need further development to expand geographic scope and incorporate additional abiotic factors. [ABSTRACT FROM AUTHOR]

To clarify the effects of mechanically dry direct-seeded rice (MD-DSR) through drilling and controlled-release compound fertilizer (CRF) on rice production, field experiments were carried out with mixed controlled-release urea; controlled-release potassium; and common urea, phosphorus and potash fertilizers as test materials. The experiment was implemented with a split-plot design, with fertilization modes as the main plots and two varieties (indica and japonica) as the subplots. The fertilization modes were a one-time application of CRF (denoted Indica and Japonica when applied to indica and japonica, respectively), a basal application of CRF followed by topdressing with urea at the tillering stage (Indica + N, Japonica + N) and three-time fertilization, representing typical farmer fertilization practices (FFP) (Indica + FFP, Japonica + FFP). The results showed that the yields of indica and japonica rice were 5.5–15.8% and 5.3–16.3% higher, respectively, under the two CRF treatments than under FFP in the 3 years of the experiment. The effective tiller percentage, shoot and root biomass, root-shoot ratio, and harvest index of the population and the biomass per plant of indica and japonica rice improved under the two CRF treatments relative to FFP. The Indica + FFP and Japonica + FFP plants exhibited higher total N accumulation but significantly lower fertilizer partial productivity than the corresponding plants under the two CRF treatments. The net benefits to indica and japonica under the two CRF treatments were higher than those under FFP. Therefore, MD-DSR combined with the one-time application of CRF can increase rice yield, reduce fertilizer and labor costs, and benefit rice production. [ABSTRACT FROM AUTHOR]

[Objective ] The aim of this study was to provide a theoretical basis for the development and application of slow release nitrogen fertilizer for rubber trees through a rubber seedling fertilizer experiment. [Method] Four different slow-release nitrogen fertilizers were applied to rubber seedlings, and their effects on biomass and nutrient accumulation for each part of the rubber seedlings were investigated. [ Result] Compared with urea application, in addition to DMPP-urea, slow-released fertilizer could increase the biomass of roots, leaves and total biomass of rubber seedlings. The average biomass of the six treatments was ranked from large to small : Fertilizer rods ( 146.64g) > humic acidurea aldehyde ( 142.36 g) >coated urea (124.14 g) > DMPP-urea (91.90 g) >urea ( 80.21 g) >CK (30.50 g), and there were no significant difference between humic acid-urea aldehyde and fertilizer rods and significantly higher than other treatments. The total nitrogen accumulation and potassium accumulation of fertilizer rods were significantly higher than that of other treatments, then the treatment of humic acid-urea aldehyde. However, there was no significant difference in the total phosphorus accumulation of coated urea, humic acid-urea aldehyde and fertilizer rod treatment. [ Conclusion ] The application of humic acid-urea aldehyde and fertilizer rod on rubber seedlings is better. [ABSTRACT FROM AUTHOR]

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Aims: Cover crops play an important role in soil fertility as they can accumulate large amounts of nutrients. This study aimed at understanding the nutrient uptake capacity of a wide range of cover crops and at assessing the relevance of acquisition strategies. Methods: A field experiment was conducted to characterize 20 species in terms of leaf and root traits. Plant traits were related to nutrient concentration and shoot biomass production with a redundancy analysis. Acquisition strategies were identified using a cluster analysis. Results: Root systems varied greatly among cover crop species. Five nutrient acquisition strategies were delineated. Significant amounts of nutrients (about 120 kg ha of nitrogen, 30 kg ha of phosphorus and 190 kg ha of potassium) were accumulated by the species in a short period. Nutrient acquisition strategies related to high accumulations of nutrients consisted in either high shoot biomass and root mass and dense tissues, or high nutrient concentrations and root length densities. Species with high root length densities showed lower C/N ratios. Conclusions: The same amounts of nutrients were accumulated by groups with different acquisition strategies. However, their nutrient concentrations offer different perspectives in terms of nutrient release for the subsequent crop and nutrient cycling improvement. [ABSTRACT FROM AUTHOR]

To identify the good peanut cultivars with the properties of high yield, high nutrient use efficiency and wide adaptability, 19 selected peanut cultivars were planted in the low champaign area and piedmont plain area of Hebei Province. By using principal component analysis, the adaptability of these 19 cultivars was evaluated for different ecological regions through comparing their 16 main traits including biomass and nutrient parameters. According to the critical value of principal component (>1.0) , the 16 biomass and nutrient characteristics were integrated into 4 principal components which accounted for 85% of the original information. The results indicated that there were obvious differences in yield and nutrient use efficiency for the peanut cultivars in different ecological regions. The 19 peanut cultivars were classified into 2 groups according to their ecological adaptability, and the cultivars from the group with wide adaptability could further be divided into 3 categories according to their yield and nutrient use efficiency. Among these cultivars, Yuhua 9719, Jihua 0212-4, Weihua 10, Yuhua 15, Puhua 28 and Jihua 10 were selected as the better peanut cultivars with the properties of high yield, high nutrient use efficiency and wide adaptability. [ABSTRACT FROM AUTHOR]

1. The importance of species diversity for the stability of populations, communities and ecosystem functions is a central question in ecology. 2. Biodiversity experiments have shown that diversity can impact both the average and variability of stocks and rates at these levels of ecological organization in single trophic-level ecosystems. Whether these impacts hold in food webs and across trophic levels is still unclear. 3. We asked whether resource species diversity, community composition and consumer feeding selectivity in planktonic food webs impact the stability of resource or consumer populations, community biomass and ecosystem functions. We also tested the relative importance of resource diversity and community composition. 4. We found that resource diversity negatively affected resource population stability, but had no effect on consumer population stability, regardless of the consumer's feeding selectivity. Resource diversity had positive effects on most ecosystem functions and their stability, including primary production, resource biomass and particulate carbon, nitrogen and phosphorus concentrations. 5. Community composition, however, generally explained more variance in population, community and ecosystem properties than species diversity per se. This result points to the importance of the outcomes of particular species interactions and individual species' effect traits in determining food web properties and stability. 6. Among the stabilizing mechanisms tested, an increase in the average resource community biomass with increasing resource diversity had the greatest positive impact on stability. 7. Our results indicate that resource diversity and composition are generally important for the functioning and stability of whole food webs, but do not have straightforward impacts on consumer populations. [ABSTRACT FROM AUTHOR]

The temporal dynamics of the biomass, as well as the carbon (C), nitrogen (N), phosphorus (P) concentrations and accumulation contents, in aboveand below-ground vegetation components were determined in the alpine steppe vegetation of Northern Tibet during the growing season of 2010. The highest levels of total biomass (311.68 g m), total C (115.95 g m), total N (2.60 g m), and total P (0.90 g m) accumulation contents were obtained in August in 2010. Further, biomass and nutrient stocks in the below-ground components were higher than those of the above-ground components. The dominant species viz., Stipa purpurea and Carex moorcrofti had lower biomass and C, N, P accumulations than the companion species which including Oxytropis. spp., Artemisia capillaris Thunb., Aster tataricus L., and so on. [ABSTRACT FROM AUTHOR]

We assessed interactive effects of varying levels of applied phosphorus fertilizer and water stress on growth, productivity, and mineral accumulation in container-grown Dalbergia sissoo L. seedlings. Height, collar diameter, leaf size and area, root volume and total biomass were reduced, and dry matter allocation to root was increased with increasing levels of soil water stress. The reduction was >32% in growth, >50% in leaf, and >77% in biomass when seedlings were grown with <50% of soil field capacity. Phosphorus application at the level of 10 mg kg-1 soil enhanced stems and leaf biomass and nutrient accumulation at all irrigation levels, and thus tolerance to drought. Phosphorus responses to growth and biomass production increased with irrigation levels. Thus, 20 mg P kg-1 soil is beneficial at sufficient soil water availability and a lower dose (i.e., 10 mg P kg-1) is recommended under high soil water stress conditions to benefit growth and productivity of D. sissoo. [ABSTRACT FROM AUTHOR]

The relocation of nutrients among dominant plant species, along with hydrological functions and soil chemistry in five plant communities, including Eucalyptus plantation, Pinus plantation, shrubland, semi-natural, and natural secondary forests were investigated in central Yunnan, China. The nutrient P, N, and K accumulation in above-ground biomass of Eucalyptus smithii (stems, barks, branches, and leaves) were the highest, followed by Pinus yunnanensis of both the Pinus plantation and the semi-natural forest. The nutrient retranslocation efficiency (NRE) of E. smithii was the highest for nutrient P, N, and K with values of 56, 66, and 67%, respectively, among the dominant plant species of the five plant communities, while the NRE of P. yunnanensis in Pinus plantation had the second highest value of NRE for nutrient N. The nutrient content (available P, N, and soil organic matter) in the upper two soil layers under Eucalyptus and Pinus plantations was correspondingly found to be lower than that of the other forests. Moreover, under the Eucalyptus and Pinus plantations, surface runoff, soil erosion, and nutrient loss were more serious, and the water storage of litterfall and canopy interception were significantly lower than that in the other plant communities. Accordingly, we suggest that single-species plantations cannot present the same ecological benefits as natural forests, because of their simple, uniform structures, and the characteristics of the dominant plant species. [ABSTRACT FROM AUTHOR]

Abstract: The high productivity associated with many tropical forest plantation species has contributed to their importance in meeting the world''s growing demand for wood products. However, there is concern that their high growth rate and intensive management system might lead to site nutrients depletion. A total of 20 stands (10–28 years) of Gmelina arborea plantations in Oluwa and Omo forest reserves, Nigeria, was used to investigate the effect of Gmelina plantation development on site nutrients, aboveground productivity and nutrient accumulation. Standing biomass ranged from 81.5 to 392.1tha−1 in the youngest and oldest stands. Regardless of stand age, biomass partitioning was about 83.0, 13.5 and 3.5% to stem, branches and foliage, respectively. The size and age of trees did not significantly affect nutrient concentration in tree components. Nitrogen, Ca and Mg contents in tree tissue increased in the order of foliage>stem>branches while that of K and P increased in the order of foliage>branches>stem. Tree tissue nutrients concentration exhibited little change with stand development. Stand nutrient accumulation followed the same trend as standing biomass, with about 80% of each nutrient stored in the stem and 20% in branches and foliage. The accumulation of nutrients in stem, branches and foliage followed the order: Mg>N>Ca>P>K>Na. Though soil nutrients were slightly depleted between 10 and 19 years and re-built up afterwards, the overall effect of stand development on soil nutrients was not statistically significant, implying that the development of Gmelina plantations did not adversely affect the soil nutrient status. Consequently, productivity during the next rotation will most likely be affected by harvesting methods of current stands and management practices of the next rotation. The 20% accumulation of aboveground nutrients in branches and foliage implies that apart from the already replenished site nutrients, there will be an additional 20% nutrient input into the soil if the branches and foliage are left on the site after harvest. For long-term site quality and sustainability of production, successive plantations should be managed on 25 years rotation as lower rotation will most likely lead to steady depletion of site nutrients. [Copyright &y& Elsevier]

Abstract: Changes in biomass, nutrient accumulation and production efficiency (PE—total biomass increment per unit leaf area) were investigated in intensively managed plantations of loblolly pine (Pinus taeda L.) using an age sequence of replicated 1-, 2-, 3-, and 4-year-old stands (n =13). All stands, located on sandy Spodosols in the Coastal Plain of southern Georgia, were managed using a similar prescription that included a common genetic source, fertilization (years 1 and 3) and understory competition control. Total biomass accumulation (above- and below-ground) ranged from about 13Mgha−1 at age 2 years to 49.7Mgha−1 at age 4 years. Dry matter distributions averaged 30%, 34%, 18%, 6%, 15%, 12% and 3% for foliage, stemwood, branches, bark, taproots, coarse roots and fine roots, respectively, at age 4 years. Intensive management and rapid growth rates markedly increased soil nutrient demands, being about 15-fold higher than that documented in extensively managed stands of comparable age. Nutrient accumulations in tree biomass at age 4 years averaged 195, 22, 86, 72 and 28kgha−1 for N, P, K, Ca and Mg, respectively. Large declines (∼50%) in PE (2.6Mgha−1 year−1/unit versus 1.3Mgha−1 year−1/unit LAI) were apparent among all sites between the second and third years, with a noted recovery occurring at age 4 years. Changes in branch and taproot PE were most apparent, whereas stemwood PE did not change appreciably between ages 2 and 3 years. Correlation analyses suggested that larger declines in PE were associated with decreasing foliar nutrient levels (dilution), although changes in growth dynamics (carbon allocation) associated with advancing stand development may have also contributed. Collectively, these results suggest that intensive management may induce multiple nutrient limitations on sandy Spodosols, and that a better understanding of nutrient requirements, including macro- and micronutrient supply, will be necessary to maintain and enhance soil quality and long-term site productivity on these soils. [Copyright &y& Elsevier]

A chronosequence of Gmelina arborea Roxb. stands ranging from 1 to 6 years old was measured to document changes in growth, biomass and nutrient (N, P and K) contents for three red lateritic sites in Chhattisgarh, India. The stand''s density, survival and growth parameters (DBH, total height, crown diameter and number of branches) varied significantly with age and site. The number of stems was highest (789 trees/ha) in a 1-year-old plantation at site 3 (Kusumi) and lowest (724 trees/ha) in a 6-year-old stand at site 2 (Anandgoan). Allometric equations for stem wood, branches, leaves and roots to tree diameter at breast height were developed to estimate above ground and below ground tree biomass. The total biomass ranged from 3.9 Mg ha−1 in 1-year-old to 53.7 Mg ha−1 in 6-year-old stand. The stem wood contributed from 55.3% (site 3) to 56.3% (site 1), branch wood from 18.3% (site 2) to 19.8% (site 3), roots from 17.9% (site 3) to 18.5% (site 2) and foliage from 6.6% (site 2) to 7.0% (site 3) of the total biomass. The growth and biomass production were poor from establishment to 3 years age and it increased by 1.5–2 times as the plantation aged from 4–6 years. Nutrient accumulation in tree biomass increased with stand age, following the pattern of biomass accumulation. The total nitrogen accumulation in 6-year-old stands at three sites ranged from 212.9 to 279.5 kg ha−1 with a mean annual storage of 238.4 kg ha−1 and total K ranged from 170.8 to 220.5 kg ha−1 with a mean annual storage of 189.9 kg ha−1. Phosphorous storage was lowest which ranged from 15.0 to 19.6 kg ha−1 with a mean storage of 16.8 kg ha−1. The organic matter and nutrients in the soils improved significantly after 6 years of planting. Available N enhanced by 14.9%, 12.0% and 11.3%, K by 10.0%, 9.1% and 10.6%, whereas phosphorous declined by 2.6%, 23.0% and 20.0%, respectively, at soil depths of 0–20, 21–40 and 41–60 cm. The paper discusses the implications of whole tree harvest at 6 years age for fire/pulpwood. [Copyright &y& Elsevier]

An experiment comprised of five treatments [T1 = municipal effluent @ 1 PET (without plant), T2 = municipal effluent @ (1/2) PET, T3 = municipal effluent @ 1PET, T4 = municipal effluent @ 2 PET, and T5 = good (canal) water @ 1 PET] was carried out with Eucalyptus camaldulensis. The aim was to utilize sewage water in growing tree plantation and to increase the supply of fuel wood to the growing urban population. Height, collar diameter, and number of branches were monitored periodically. Biomass and leaf and root growth were recorded at 24 months of age. Mineral composition and uptake were monitored to observe their removal from the soil. Increase in rate of municipal effluent application was associated with better tree growth compared to irrigation with canal water. At 24 month age, the T4 was the best treatment in which E. camaldulensis attained 393 cm height and 6.6 cm collar diameter. Height and collar diameter of T2 seedlings did not differ (P > 0.05) with respective parameters in T5 treatment. Collar diameter increased by 1.2 times in T3 treatment. Number of leaves and biomass increased with increase in quantity of municipal effluent. Modeling of total biomass against quantity of municipal effluent application produced better result with non-linear fitting than the linear one. Mineral composition and accumulation in different parts of the seedling was high and varied with the quantity and nutrient composition of irrigation water. Concentration of total nitrogen (N), phosphorus (P), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) was high in the municipal effluent irrigated seedlings compared to the good water irrigated seedlings. However, sodium (Na), potassium (K), calcium (Ca), and magnesium (Mg) were high in the seedlings of T5 compared to T2 and T3 treatments. Municipal effluent did not show any toxicity to the seedlings up to 24 months age. Conclusively, the municipal effluents could be recommended as a good source of water and nutrient for tree biomass production to fulfill the requirement of fuel need in the suburban area. [ABSTRACT FROM AUTHOR]

• Selective management increased the diversity of abandoned farmland. • The manipulation of competitive relationships enhanced C and nutrient accumulations. • The management of natural regeneration provided positive effects on soil quality. • The increased diversity provides the recovering of additional ecosystems function. Our aims were to describe the role of the selective management of regenerating community (RC) on the recovery of ecosystem functions in production areas of African mahoganies under mixed stands and agroforestry systems, established on abandoned farmland. A randomized block experiment was set up with the following treatments: (T1) mixed-plantation of African mahogany under conventional system (including herbicide application); (T2) mixed-plantation of African mahogany with selective conduction of RC; (T3) agroforestry system with African mahogany; (T4) agroforestry system with African mahogany with selective conduction of RC. The parameters of horizontal structure, diversity and ecological attributes of species of the regenerating community were studied. In addition, the production of aboveground biomass and nutrient stocks, soil fertility, and soil microbial activity were assessed. In T1, herbicide application (glyphosate) affected the floristic composition of the regenerating community by reducing the dominance of monocots and Pteridium arachnoideum , allowing the regeneration of other taxonomic groups of herbaceous species. In response, there was a reduction in the litter biomass stock comparing to the other treatments. The treatments with selective management of the RC (T2 and T4) produced more biomass and accumulated higher amounts of C and nutrients than the conventional treatments (T1 and T3). These treatments also allowed other shrub and tree species to overcome the ecological filter imposed by grasses and colonize the experimental area. Baccharis dracunculifolia , Vismia guianensis , Cecropia pachystachya and Inga sp. were the most important regenerating species that contributed most to the stocks of all nutrients in living aboveground biomass. Pruning and selective management in T4 increased the soil effective cation exchange, while in the T1 treatment there was a lower activity of the β-glucosidase enzyme. The selective management of RC in agroforestry systems through the manipulation of competitive relationships allowed the colonization of native tree and shrubby species that provide several additional ecosystem services, including pollination, fauna attraction, food production, pest control and environmental regulation for the agroecosystem. [ABSTRACT FROM AUTHOR]

• We estimated rubber tree biomass and nutrient stocks over a plantation cycle. • Nutrient accumulation rate in trees peaked between 2 and 5 years after planting. • 25–36 % of the stocks of N, P and K at the clear-cut stage were accumulated at 5 years old. • Logging residues could account for 120–1126 % of the nutrient input through fertilizers over the entire rotation. Rubber trees are the main source of natural rubber (NR). The area occupied by rubber plantations rose from 3.9 million ha in 1961 to 12.5 million ha in 2018. Both the expansion of rubber plantations in marginal zones (prone to biotic and abiotic stress), and long-term rubber tree cultivation in traditional areas, raise questions about the sustainability of NR production in a context of climate change. Our study set out to gain insights into the biogeochemical cycles in rubber plantations, for a better matching of fertilizer inputs to the dynamics of nutrient demand throughout rubber tree growth. Nutrient accumulation in tree biomass is a major component of the biological cycle in tree plantations. We studied the dynamics of biomass and nutrient accumulation in two chronosequences covering the whole lifespan of a plantation in Ivory Coast managed on a sandy soil at the SAPH site, and one on a clayey soil at the SOGB site. In total, 56 trees were destructively sampled in 2-, 5-, 20- and roughly 40-year-old stands. While the use of allometric relationships is common for estimating nutrient stocks in planted forests, this study was the first to provide allometric equations predicting nutrient stocks in rubber tree components. Allometric models were applied to the inventory of 4 commercial stands, for each age at each site, to estimate stand biomass and nutrient stocks. The current annual increments of nutrient stocks in tree biomass peaked between 2 and 5 years after planting. They reached 80 kg ha-1 yr-1 for N, 14 kg ha-1 yr-1 for P and 34 kg ha-1 yr-1 for K at SAPH (53, 7, and 39 kg ha-1 yr-1 respectively at SOGB), which highlighted the importance of an appropriate fertilization schedule for young rubber trees. At the clear-cut age (38–40 years), the amounts of nutrients accumulated in tree biomass were 970 kg N ha-1, 188 kg P ha-1, 366 kg K ha-1, 941 kg Ca ha-1 and 255 kg Mg ha-1 on the sandy soil at SAPH (907,118, 629 1499, and 375 kg ha-1 respectively on the clayey soil at SOGB). Contrasting soil properties and management practices at the two sites had a much greater effect on the amounts of P, K, Ca and Mg accumulated in the trees than on N accumulation. Logging practices in rubber plantations can lead to considerable nutrient exports on poor tropical soils. Harvest residues should be distributed uniformly in the plots so that the roots of young trees can quickly gain access to the nutrients released during decomposition. [ABSTRACT FROM AUTHOR]

New shoots (including newly formed leaves and twigs) and fruits of citrus tree are key organs for present yield formation and flower differentiation in the next season, but the relationship between yield fluctuation and accumulations of major nutrients in new shoots and fruits of citrus tree is still unclear. Thus, to quantify the biomass and mineral nutrient accumulation in new shoots and fruits of citrus trees under varied yield levels has essential significance for rational fertilization and pruning management for citrus orchards. The purpose of this study was, therefore, to investigate the accumulation of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg), and the distribution of biomass in new shoots and fruits of citrus trees under low, medium and high-yield levels in each of eight orchards located in Chongqing, China. The results showed that substantial variation of fruit yield was observed in all eight orchards with an average yield of 15.0 (low), 30.9 (medium) and 60.1 (high) kg/plant. The averaged biomass of new shoots ranged from 1.59 to 2.51 kg/plant, which was significantly and positively correlated with fruit yield. Nutrient accumulation in leaves was generally highest among new organs, while more than half of N (52.70–71.4%), P (66.5–80.4%) and K (68.9–85.9%) accumulated in fruit. Fruit yields closely correlated with total amounts of major nutrients in new shoots. Furthermore, the nutrient requirements per unit of newly developed shoots and fruits were gradually decreased with increased yield, but the removed nutrients per ton of fresh fruit were almost stable, indicating that more nutrients were distributed into fruit tissues. Taken together, these findings are valuable for optimizing nutrient and pruning management in citrus orchards in China and other similar countries. [ABSTRACT FROM AUTHOR]

Through this study, the most suitable fertilization ratio, amount and frequency were determined, providing a scientific reference for further fertilization management for Magnolia wufengensis (Magnoliaceae) seedlings. Fertilization is an important cultivation and management measure to maintain forest seedling health and rapid growth. However, improper fertilization can also have unexpected effects: inhibiting seedling growth, increasing the cost of production and contaminating the environment. Thus, to explore the most suitable fertilization treatment for Magnolia wufengensis growth, one-year-old Magnolia wufengensis seedlings and the orthogonal design method were used in this study. Three different fertilization frequencies were used combined with 9 NPK ratios. The growth index, chlorophyll content, nutrient content in tissues, nutrient transport efficiency, nutrient uptake, and soil properties were analyzed. Fertilization can increase chlorophyll content, promoting the vegetative growth and biomass accumulation of Magnolia wufengensis. Fertilization reduced the proportion of root biomass to whole plant biomass, resulting in an increase in stem biomass with little effect on leaf biomass. Additionally, fertilization also increased the proportion of N in roots, P in stems and K in leaves. Under fertilization, the K transport efficiency was higher than that of N and P. Furthermore, there was a positive correlation between the nutrient use efficiencies of N and K. Overall, the effects of six fertilizer applications were much better than those of four and eight fertilizer applications on the promotion of vegetative growth, biomass and nutrient accumulation, nutrient uptake and transport efficiency. The results showed that six fertilizer applications with an NPK ratio of 3:2:1 as follows: N application at 480 mg/plant, P application at 320 mg/plant, and K application at 160 mg/plant was the most suitable fertilization method for plant growth. [ABSTRACT FROM AUTHOR]

A positive nutrient balance is crucial to sustaining forest productivity. Differences in stand densities usually mean different aboveground biomass stocks and different proportions of tree compartments. These differences can be reflected in the different macronutrient stocks between stands of different densities, because various tree compartments have different element concentrations. In this study, 82-year-old stands of Scots pine were compared, and specifically, the concentrations of the elements in tree compartments and the amounts of macronutrients in aboveground biomass were compared. The nutrients considered in this study were nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. A positive correlation between stand density and the level of stored macronutrients was found for nitrogen, phosphorus, and potassium. This result means that forest managers can influence nutrient balances by regulating stand densities or by harvesting methods (SOH: stem-only harvesting or WTH: whole-tree harvesting). [ABSTRACT FROM AUTHOR]