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To improve cotton yield in salinized arid fields, excess salt is removed and phosphorus content is increased. Adjusting phosphate fertilizer timing with water and fertilizer reduces phosphorus binding with calcium ions. Salt removal precedes phosphate application, enhancing soil phosphorus availability and promoting better growth. However, the optimal time for delaying phosphate fertilizer drip irrigation remains unclear. Therefore, this study evaluated the total salt, soil available phosphorus, and cotton yield under the condition of delayed phosphate fertilizer application. We conducted a field experiment using a completely randomized design to adjust the timing of phosphatic fertilizer application and apply the same amount of pure phosphorus. Specifically, “t” was defined as the total duration of one irrigation cycle, and the starting points for phosphorus application were as follows: T1, 1 h; T2, 1 h + 1/3 t h; T3, 1 h + 2/3 t h; CK, 1/3 t h. These values represent the duration of salt leaching through irrigation in each treatment. Phosphate fertilizer was applied to the soil after salt washing was complete. The results revealed that the T2 treatment exhibited the highest SPAD value (64.53), which was 11.46% and 15.48% higher than that of the T1 and T3 treatments. The 0–20 and 20–40 cm soil layers under the T2 treatment had the highest pH values of 9.12 and 9.37, representing increases of 1.93%, 1.21%, 4.50%, and 1.38% compared with T1 and T3 treatments, respectively (p < 0.05). At the bud stage, the Olsen-P in the T2 treatment was 82.86% and 26.53% higher than that in the T1 and T3 treatments, respectively (p < 0.05). The T2 treatment achieved the highest yield of 6492.09 kg/hm2, which was 31.47%, 31.53%, and 2.77% higher than that of T1, T3, and CK. Overall, the T2 treatment increased cotton yield and reduced the adsorption of calcium ions to available phosphorus in salinized soil. This study provides an effective technical approach for the sustainable development of salinized cotton fields in Xinjiang.

In soils, pH stands as the main factor modulating bacterial communities’ composition. However, most studies address its effects in bulk soils in natural systems, with few focusing on its effects in the rhizosphere of plants. Predicting pH effects in the rhizosphere is an important step towards successful microbiome manipulation, aiming to increase crop production. Here, we modulated an acidic soil’s pH to four different ranges (4.7, 5.2, 7.5 and 8.2), while correcting for fertility differences among ranges, thus isolating pH effects from other physicochemical characteristics. Then, two crops with distinct metabolisms (maize and bean) were cultivated in a greenhouse experiment and the effects of pH and cover crops on the rhizosphere bacteriome after 90 days explored through 16S rRNA gene sequencing, aiming to characterize pH effects on the rhizosphere of two different plants across this gradient. Alpha diversity indexes (OTU richness and Shannon index) were statistically different with pH but not crop species, with an interaction among factors. For beta diversity, both pH and crop species were significant modulators of community composition, without an interaction, but pH effects were 2.5 times bigger than those of plant species. Additionally, strong and significant positive correlations were observed between pH and Bacteroidetes and Deltaproteobacteria, while Actinobacteria, Planctomycetes and Acidobacteria were negatively correlated with pH. Regarding OTUs, 27 and 46 were correlated with pH in maize and bean’s rhizosphere, respectively, while 11 were shared between them. Altogether, these results provide valuable information on the isolated effect of pH in the rhizosphere of important crop plants, aiding future microbiome manipulation studies.

Arbuscular mycorrhizal fungi (AMF) and rhizobia play a pivotal role in enhancing crop productivity, shaping microbial community structure, and improving soil quality, making them key components for sustainable ecosystem development. The symbiotic relationship between AMF and rhizobia is crucial for facilitating efficient biological nitrogen fixation and nutrient absorption, thereby reducing the dependence on chemical fertilizers and promoting sustainable agricultural practices. The findings of various studies, however, indicate that soil environment can impede the symbiotic relationship between AMF and rhizobia. We conducted a comprehensive meta-analysis of 158 articles from 1980 to 2022 to explore the synergistic interactions in legume–AMF–rhizobium systems and the potential mechanisms underlying this synergism. Our findings revealed that the inoculation with AMF and/or rhizobia significantly (p < 0.001) increased legume plant nitrogen content, phosphorus content, shoot biomass, yield, AMF colonization rate, and the number and weight of nodules compared to uninoculated controls (effect size d > 0). Moreover, there was a substantial synergistic effect between AMF and rhizobia (p < 0.001). Nevertheless, soil salinity stress, drought stress, and pH stress could hinder the positive effects of inoculation treatments, possibly due to the plant trade-off strategies under abiotic stress conditions. This research may potentially lead to new solutions for sustainable agricultural systems amidst the challenges posed by global climate change.

Nitrogen (N) fertilizer is routinely applied in highbush blueberry (Vaccinium corymbosum L.) production. The recommended N fertilizer rate increases as the plants mature, and is usually determined based on regional growing conditions. However, the effects of N fertilizer rates and application methods over the long term remain poorly understood. In this study, ammonium sulfate was applied as an N source at the recommended rate (100%), which corresponds to a maximum of 155 kg N ha−1 for plants older than eight years, along with higher rates at 150% and 200% of the recommended level, as well as a control treatment of no N. Treatments were applied to the blueberry cultivar ‘Duke’ as either broadcast (BROAD) or fertigation (FERT), and impacts were analyzed after 12 and 13 years of treatment. In the 14th year, the 100% N rate was uniformly applied as BROAD across all plants to separate the effects of different N rates from those caused by long-term soil condition changes. The BROAD treatment at the 100% N rate achieved the highest yield, and the FERT treatment at 200% resulted in the lowest yield in the 12th year, suggesting that excessive N rates can reduce fruit yield. However, no significant yield differences were observed in the 13th year. Higher N rates were associated with reduced titratable acidity in fruits and fewer flower buds. The soil pH declined across all N treatments, with the FERT at 200% showing the most significant reduction. All N treatments generally increased soil electrical conductivity (EC). High N rates also decreased plant accumulation of magnesium, calcium, and copper, with the latter reaching deficiency levels. These findings emphasize the importance of adhering to recommended N application rates and adjusting soil pH and EC to mitigate the adverse effects of prolonged N treatments.

Tuber aestivum is a key truffle species with significant ecological and economic value. Despite its importance, plantation success can be influenced by soil pH, host plants, and undesired fungi. This study examines how soil pH and host plants influence mycorrhization trends in T. aestivum plantations across six plant species in eight Hungarian settlements, using root sampling and DNA analysis to assess plantations at three and six years of age. Tuber aestivum achieved over 30% mycorrhization, with Carpinus betulus showing the highest levels. DNA analysis identified eight undesired mycorrhizal fungi, with Suillus spp. (42.9%) and Scleroderma spp. (31.4%) being the most prevalent. The study found that T. aestivum preferred a soil pH of around 7.6, while undesired fungi thrived in slightly acidic conditions. Additionally, soil pH significantly and positively influenced T. aestivum mycorrhization; however, factors such as plantation age also contributed to mycorrhization trends. While mycorrhization by undesired fungi decreased with higher soil pH, it increased as plantations matured from three to six years. These findings highlight the need for the effective management of soil pH and the control of undesired fungi to optimize T. aestivum mycorrhization, emphasizing the importance of targeted strategies and further research for sustainable truffle cultivation.

Ticks are ectoparasites of a wide range of animals and are important vectors of numerous pathogens affecting humans, livestock, and pets. This study investigates possible correlations between selected factors, altitude, soil pH, and a factor called ‘amount’ (number of ticks examined in pooled samples) on the occurrence of I. ricinus ticks positive for selected tick-borne microorganisms. Questing I. ricinus ticks were collected in 2016 and 2017 across various altitudes, at two mountain ranges in central Slovakia. Tick pools were screened for the presence of Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato (Bbsl), Babesia/Theileria spp., Rickettsia spp., and tick-borne encephalitis virus (TBEV) using molecular methods. Regression analysis was employed to evaluate relationships between selected factors and the occurrence of vector-borne microorganisms. This study revealed a statistically significant influence of altitude on the occurrence of A. phagocytophilum; increasing altitude of the sampling site was associated with increased probability of pathogen occurrence. For Babesia/Theileria spp., neither altitude nor soil pH significantly affected pathogen occurrence. The occurrence of Bbsl was notably impacted by both altitude and soil pH; higher altitudes were associated with a decreased probability of pathogen presence, whereas higher soil pH increased the likelihood of pathogen occurrence. The presence of Rickettsia in a pooled sample was not affected by altitude and soil pH, but the ‘amount’ factor was a significant predictor, increasing the probability of pathogen detection. Neither altitude nor soil pH had a significant impact on TBEV occurrence. The regression models showed moderate goodness-of-fit levels to the data, underscoring their utility in examining the role of altitude and soil pH on pathogen occurrence. However, they explained only a small portion of the overall variance in pathogen occurrence, indicating the presence of other significant factors not covered in this study.

This research aimed to assess the effect of applying digestate fractions and conventional mineral nitrogen (N) fertilizers on plant and soil properties, as well as potential nitrate leaching, in acidic soil over two consecutive years (2018 and 2019). The digestate fractions were obtained after the anaerobic co-digestion of maize silage and liquid cattle manure (LCM). Seven different treatments were applied to the maize crop in four replicates: unfertilized control (C), mineral fertilizer (MF), LCM, solid fraction of digestate (SFD), liquid fraction of digestate (LFD) and a mixture of SFD and LFD with MF (50% of total N from digestate fractions + 50% of total N from MF). The highest maize yields were achieved on average in 2018. Statistically, the highest dry grain yield was observed in the MF treatment (12.1 t ha−1) and in the mixtures of MF+SFD (11.0 t ha−1) and MF+LFD (11.8 t ha−1), while the lowest yield was achieved in both years in the C treatment (7.9 t ha−1). The N fertilizer replacement value was statistically highest on average in the MF treatment (100%) and in the mixtures of MF+LFD (80.5%) for both years. The experiment results could inform legal guidelines and standardize digestate application on agricultural land in Croatia and the European Union (EU).

The low solubility and enhanced fixation of zinc (Zn) in semi-arid and dry climates limits Zn uptake in plants. Zn deficiency in soil impairs crop production and human health, necessitating agricultural biofortification. A pot experiment was conducted to evaluate the effect of Zn and various types of manure on the Zn biofortification of lentils. The treatments, consisting of a control (Con), normal manure (NM), composted manure (CM), and acidified manure (AM), were applied under saline soil (EC 8.00 dS m−1) and non-saline soil (EC 1.48 dS m−1) conditions along with two levels of Zn, including Zn at 0 kg ha−1 (native soil Zn = 2.2 mg kg−1) and Zn at 25 kg ha−1 (62.2 mg Zn kg−1 soil was achieved). The AM was prepared by adding sulfur and sulfur-oxidizing bacteria to the composted manure. All the manures were applied at 1% (w/w), and ZnSO4 (33% Zn) was used as a Zn source. Lentil variety Masoor 2021 was cultivated as a test crop in five replications of each treatment arranged in a completely randomized design. Applying AM with Zn considerably increased the lentils’ growth, yield, and Zn content under saline and non-saline conditions. Under non-saline soils, the treatment of AM + Zn significantly promoted the Zn content in the root (132.5%), shoot (91.7%), grain (49.1%), root length (79.7%), plant height (33.7%), and SPAD value (29.9%). Under saline conditions, application of AM + Zn promoted uptake of Zn in the root (218.5%), Zn content in the shoot (175.7%), Zn accumulation in the grain (107.7%), root length (109.7%), plant height (37.8%), and SPAD value (52.8%) compared to the control. According to the results, lentils should be grown with AM and Zn to increase their growth, yield, and Zn content significantly. This is a cost-effective and sustainable way to combat Zn deficiency in lentils.

Tea plant is an acidophilic plant, and soil pH has an important effect on the absorption and enrichment of elements, tea plant growth and quality. In this study, rhizosphere soils and leaves of tea plants from 30 tea plantations were collected to determine soil pH and multi-element content of soil and leaves of tea plants, to obtain and validate key elements that are enriched by pH affecting tea plants, and to analyze the effects of pH on the growth and quality of tea plants. The results showed that soil pH significantly affected the enrichment of 15 elements by tea plants, and the enrichment coefficients of 11 elements (C, Mg, Si, N, P, Mn, Sr, Cd, S, Ca and Sb) tended to increase significantly with the increase of soil pH, while the opposite was true for the other four elements (Cu, Rb, Ba and Al). TOPSIS analysis showed that soil pH had the greatest effect on tea plant enrichment of seven elements, namely N (100%), Mn (43.32%), C (39.22%), P (27.66%), Sr (15.30%), Mg (13.41%) and Ba (10.47%). Pot experiments with tea seedlings also verified that soil pH significantly affected the enrichment of tea leaves for seven key elements. Moreover, with the increase of soil pH, the growth indexes, photosynthesis indexes and quality indexes of tea seedlings showed a significant upward trend. Interaction analysis showed that the enhanced enrichment of N, Mn, C, P, Sr and Mg by tea plants was beneficial to increase the photosynthetic capacity of tea plants, promote the growth of tea plants and improve the quality of tea leaves. This study provides an important theoretical basis for the cultivation and management of tea plants.

Mercury (Hg) is a highly toxic contaminant posing serious ecological and human health risks. This study investigates the Hg transfer characteristics and prediction models in a soil–lettuce system, employing bioconcentration factors (BCF), path analysis (PA), and Freundlich-type functions. A pot experiment was conducted in a greenhouse, where lettuce was grown in a range of Chinese agricultural soils (n = 21) and deliberately spiked with Hg using Hg(NO3)2 solution. The results indicated that lettuce grown in Hg-spiked acidic soils (pH < 6.5) accumulated total Hg (THg) levels up to 14.01 µg kg−1, surpassing the safe consumption limit of 10 µg kg−1. The BCF for lettuce THg was less than 1.0, suggesting a low transfer of Hg from soil to lettuce. Notably, BCF values were significantly higher in acidic soils (0.02) compared to alkaline soils (0.005). Path analysis accounted for 82% of the variation in lettuce THg content, identifying soil THg, pH, and amorphous (Amo) Al and Fe oxides as primary direct factors. Additionally, soil-available Hg (AvHg), exchangeable Hg (ExHg), clay, and organic matter (OM) were significant indirect factors affecting lettuce THg content. To validate the findings of the path analysis, an extended Freundlich-type equation was developed using stepwise multiple linear regression (SMLR). This model exhibited high predictive accuracy (R2 = 0.82, p ≤ 0.001), with soil pH, THg, and amorphous Al and Fe oxides being the key variables for predicting Hg transfer in the soil–lettuce system. The insights from this study can guide the management of safe lettuce production in Hg-contaminated soils, ensuring the mitigation of Hg exposure through agricultural produce.

Soil pH significantly impacts microbial activity and community assembly, which in turn determines the temperature sensitivity (Q10) of soil respiration. Due to the high soil acidification in China, it is necessary to understand how soil acidification impacts Q10. Here, the Q10 of soil respiration was examined in a long-term field experiment (1982–present) with different soil pH caused by fertilization management. In this experiment, we selected treatments with neutral pH: (1) no crops and fertilization (CK); (2) crops without fertilization (NF); low pH with (3) crops with chemical fertilization (NPK); and (4) crops with chemical fertilization combined with wheat straw incorporation (WS). Under natural soil temperature changes, we observed that soil acidification lowered the Q10 value of soil respiration. Considering only temperature changes, the Q10 of soil respiration was strongly associated with microbial community composition, alpha diversity, and soil ammonium nitrogen. Considering the interaction between soil pH and temperature, warming strengthened the negative effect of soil pH on the Q10 of soil respiration, and the pathway through which soil pH mediated Q10 included not only microbial community composition, alpha diversity, and biomass but also the soil’s available phosphorus. This work enhanced our insights into the relationships between Q10, temperature, and soil pH by identifying important microbial properties and key soil environmental factors.

Understanding soil phosphorus (P) distribution and its key drivers is fundamental for sustainable P management. In this study, a 21-year fertilization experiment on black soil was carried out, setting up five fertilization treatments: unfertilized control (CK), nitrogen and potassium (NK), nitrogen, P and potassium (NPK), NPK plus straw (NPKS), and NPK plus manure (NPKM). The distribution and effecting factors of P pools within soil aggregates were investigated. Compared to CK, the NK and NPK treatments decreased calcium-associated P concentration in all aggregate fractions. Meanwhile, the NPK treatment significantly increased the organic P extracted from NaOH in unaggregated particles (3, and NaOH increased as aggregate size increased. This was mainly because straw or manure addition promoted soil organic carbon (SOC) storage in aggregates, creating more sorption sites via association with amorphous metallic minerals, and, thus, facilitating P accumulation. In conclusion, decreasing soil pH by chemical fertilizers is an effective strategy for mobilizing soil P, whereas increasing SOC by straw or manure facilitates P accumulation.

There is growing concern regarding cadmium (Cd) exposure through rice consumption. Compared with alternate wetting and drying (AWD), continuous flooding (CF) is usually considered as an effective approach for reducing Cd enrichment in rice but increases the risk of pollution from arsenic (As). In this study, the field trial was conducted to investigate remediation effects of two water management (CF and AWD) techniques on Cd pollution in rice in typical japonica rice cultivation areas with varied soil pH levels. The results indicate that soil pH was a crucial factor in regulating CF-mediated Cd/As accumulation and migration in rice plants, and grains at all stages of rice growth. In acidic fields, compared with AWD, the use of CF reduced the accumulation of Cd in plants during the tillering stage; CF during the milk stage promotes the risk of contamination of Cd in rice grains and any form of As in plants and inhibits the content of any forms of As in grains. During the mature stage, CF reduced the levels of Cd in the plants and grains while promoting the accumulation of As(V) and total As(T-As) in plants and As(III) in grains. In alkaline fields, compared with AWD, CF during the tillering stage promoted the accumulation of various forms of As in plants. During the milk stage, CF increased and decreased the Cd content in plants and grains, respectively, and reduced the accumulation of T-As in plants and As(III) in grains; during the mature stage, CF promoted the accumulation of Cd in plants and grains, induced the accumulation of T-As plants, and inhibited the accumulation of any form of As in grains. From the perspective of food safety, the impact of CF conditions on the accumulation of Cd and As in rice from acidic fields exhibited a pattern of reduction in Cd and increase in As during the maturity period, as compared to that on the AWD. Conversely, CF increased the Cd risk while simultaneously reducing the As accumulation in rice grains to a safe level in alkaline fields. CF is not recommended as a remediation strategy for Cd pollution in rice in low Cd pollution areas, but it can be considered as a potential strategy for As pollution remediation in rice in alkaline fields with low Cd pollution.

Manganese toxicity is a major obstacle to agriculture in acid soils. Dark pericarp disease (DPD) is a newly spread physiological disorder induced by excess Mn in litchi, leading to undesirable fruit appearance and substantial economic loss. In this work, broadcast of alkaline soil conditioner in winter, followed by foliar sprays of ascorbic acid and sulfur solution at fruit development, was adopted to examine the effect of these combinations on DPD alleviation in a litchi orchard, with DPD morbidities of 70~85% in recent ten years. The combination of soil conditioner broadcast and foliar water spray was used as the control. At harvest, DPD incidence was significantly decreased by sulfur spray (3.3 ± 1.0%) and slightly reduced by ascorbic acid spray (10.7 ± 8.0%) compared to the control (12.9 ± 7.6%). Soil pH and available Mn were significantly increased and reduced by the soil conditioner broadcast. Sulfur spray significantly inhibited Mn uptake but enhanced the accumulation of Mg, Ca, sugars and cyanidin-3-rutinoside in the pericarp, leading to improved fruit pigmentation. Antioxidase activities were regulated to resist Mn stress by sulfur spray. The spray of ascorbic acid could not mitigate DPD as expected, probably due to the dose used. Conclusively, this study provides a practicable approach to mitigate Mn phytoavailability in acid soils.

Lilium growth is severely impeded by continuous cropping, and crop rotation is essential to reducing the detrimental effects of monocultures. Soil (0–20 cm) was collected in three Lilium cropping patterns in Longshan County, Hunan Province, including continuous Lilium cropping (Lilium), corn upland rotation with Lilium (Corn), and paddy rotation with Lilium (Rice). Using Illumina high-throughput sequencing technology, the fungal ribosomal DNA internal-transcribed spacer 1 (ITS1) was examined to evaluate the features of soil fungi communities among three cropping patterns. Crop rotation has an impact on soil properties and the microbial community. Rice soil has a significantly higher pH than Lilium and corn soil, while corn and rice soil have a greater total nitrogen and total phosphorus content than Lilium soil. Rotation cropping clearly shifted the fungi community diversity based on the results of principal coordinate analysis (PCoA) and nonmetric multidimensional scaling (NMDS). Ascomycota was the most prevalent phylum, with the highest levels in Lilium soil. Genetic analysis revealed that paddy rotation led to a clear reduction in or non-detection of eight potentially pathogenic fungal genera and a noticeable accumulation of eight beneficial fungal genera compared to Lilium continuous cropping. Fungi communities and their abundant taxa were correlated with soil pH and nutrients. Altogether, we propose that rice rotation, with its ability to mitigate soil acidification, reducing pathogenic and accumulating beneficial communities, may be an effective strategy for alleviating the continuous cropping barrier.

Biochar application has the potential for mitigating N2O emissions from agricultural soils and has been suggested as a management practice to ameliorate soil fertility and increase crop productivity. Nevertheless, the influence of biochar addition on N2O emissions from soils with different pH levels is not yet clear, which results in a poor understanding of the mechanisms regarding biochar application to soil N2O mitigation. A 40-day incubation experiment was carried out in the present study to investigate the impact of biochar on N2O emissions from soils with different natural pH. Four treatments (control, nitrogen fertilizer application, biochar amendment, and N plus biochar amendment) were set up separately in soils with three different natural pH levels (acidic vegetable soil, neutral rice soil, and alkaline soil). Our results showed that adding biochar significantly decreased N2O emissions by 20.8% and 47.6% in acidic vegetable soil for both N and no N addition treatments, respectively. For neutral and alkaline soils, the reduction of N2O emissions by biochar amendment was only significant for N addition treatments in alkaline soil. Soil pH and NO3−-N concentration were significantly affected by biochar amendment (soil pH increased by 1.43–1.56, 0.57–0.70, and 0.29–0.37 units for acidic vegetable soil, neutral rice soil, and alkaline soil, respectively). Thus, biochar amendment could be used as an effective management practice for mitigating N2O emissions from acidic and alkaline soils.

Soil bacteria are crucial components of terrestrial ecosystems, playing an important role in soil biogeochemical cycles. Although bacterial community diversity and composition are regulated by many abiotic and biotic factors, how soil physiochemical properties impact the soil bacteria community diversity and composition in wetland ecosystems remains largely unknown. In this study, we used high-throughput sequencing technology to investigate the diversity and composition of a soil bacterial community, as well as used the structural equation modeling (SEM) method to investigate the relationships of the soil’s physicochemical properties (i.e., soil pH, soil organic carbon (SOC), total nitrogen (TN), ammonium nitrogen (NH4+N), electrical conductivity (EC) and nitrate nitrogen (NO3−N)), and soil bacterial community structures in three typical wetland sites in the Sanjiang Plain wetland. Our results showed that the soil physicochemical properties significantly changed the α and β-diversity of the soil bacteria communities, e.g., soil TN, NH4+N, NO3−N, and SOC were the main soil factors affecting the soil bacterial α-diversity. The soil TN and pH were the key soil factors affecting the soil bacterial community. Our results suggest that changes in soil pH indirectly affect soil bacterial communities by altering the soil nitrogenous nutrient content.

Plant growth and health are affected by 0.06–0.09% of crustal fluoride. A semi-empirical model estimated wet soil fluoride using Sentinel-1 5.405 GHz data as dependent on dielectric components and loss angles. Mineral surface charges and electrical potential limited clay soil ion mobility via moisture and permeability. Real and imaginary dielectric components approximated a 3° to 4° loss angle in lab soil samples with high and low fluoride electrical conductivity. An estimated percentage of dielectric component loss over wide areas could have implied fluoride. Finally, linear regression between field fluoride value and conductance loss was used to estimate fluoride. The statistical differences (R2 = 0.86, RMSE = 1.90, and Bias = 0.35) between predicted and simulated fluoride levels over clay soil and soil with different vegetation development suggest that C-band SAR data may detect fluoride.

Biochar is commonly used to improve acidic soil and reduce nitrogen loss. However, the impact of biochar on soil nitrogen retention, especially at varying pH levels, is not fully understood. Soil samples were obtained from an acidic red soil citrus orchard. The soil pH was adjusted using CaO, with five levels (4.0, 5.1, 5.8, 6.6, and 7.2), and two biochar doses (0% and 1%) were applied. The study used 15N-Tracer and Ntrace to investigate biochar’s influence on soil nitrogen retention at different pH levels. The results showed that soil amendment with biochar improved gross mineralization rates (TM) and gross NH4+ immobilization rates (TI), except at pH 4.0 for TI. Biochar enhanced heterotrophic nitrification (ONrec) within pH 4.0–7.4, with a threshold for autotrophic nitrification (ONH4) at pH 6.4. The findings revealed biochar’s positive effect on soil nitrogen retention within pH 4.5–6.4. Biochar had a greater impact on TI than TM and inhibited ONH4, potentially enhancing nitrogen retention in this pH range. These results highlight the significance of considering biochar incorporation for improving nitrogen use efficiency and reducing NO3−-N loss in subtropical pomelo orchards.

Swine manure is widely used for ameliorating red soil acidification, but little information is available about its effect on N2O emissions. To explore the effects, a 35-day incubation experiment was conducted with two soils under different fertilization history: chemical fertilizers only (F) and combination of chemical fertilizers with swine manure (M). The treatments included no fertilizer (control), 100% N from urea (M0), and urea plus swine manure, which supplied 20% (M20), 40% (M40), 60% (M60), and 100% (M100) of total N. Soil N2O emission rates, pH, exchangeable acidity, mineral N species, dissolved organic carbon and nitrogen, microbial biomass carbon, and their inner relationships were examined. The N2O emission rates markedly increased following the treatments, reached peaks before day 2, and thereafter decreased sharply to the level of the control by day 25, 25, 23, 15, and 9 in F soil and by day 25, 25, 23, 19, and 11 in M soil for M0, M20, M40, M60, and M100 treatments, respectively. As swine manure application rate increased, the cumulative N2O emissions of F soil decreased significantly, while, for M soil, there was no significant difference among M0, M20, M40, and M60 treatments, which were higher than the M100 treatment. At the end of incubation, soil pH in F and M soils followed the order M0 < M20 < M40 < M60 < control < M100 and vice versa for exchangeable Al3+ and acidity. F soil had relatively higher NH4+-N concentration in M0 treatment and higher NO3−-N concentrations in M0 and M20 treatments than M soil. Soil pH and NH4+-N had the greatest relative contribution to N2O emissions. Overall, this study indicates that partial chemical N replacement by swine manure could effectively mitigate N2O emissions from acidic red soil primarily because of mineral N immobilization and alleviated red soil acidification. Thus, swine manure has the potential to co-ameliorate red soil acidification and N2O emission. Further research is needed to determine the effect of swine manure on N2O emission reductions under field conditions and the overall benefit in effective N management.

The cultivation of Chinese cabbage is a crucial source of daily vegetable supply for both human consumption and livestock feed, particularly in East Asian countries. However, changes in global climate and land usage have resulted in significant shifts in the ecological conditions suitable for Chinese cabbage production, thereby threatening its productivity. To address this issue, this study was conducted to map the bio-geophysical suitability of Chinese cabbage in East Asia (Japan, Northeast China, South Korea, and North Korea) from 2001 to 2020. This study integrated six key factors—temperature, rainfall, photosynthetically active radiation (PAR), soil nitrogen, soil pH, and soil texture—into a seasonal and monthly bio-geophysical suitability assessment using a GIS-based Analytic Hierarchy Process–Multiple-Criteria Decision-Making Analysis (AHP-MCDA). The levels of bio-geophysical suitability were categorized into four levels: optimal, suitable, marginal, and unsuitable. The findings of the study firstly indicate that summer is the optimal season for Chinese cabbage cultivation, as it was found to have the highest level of optimal suitability among the four seasons in East Asia. South Korea has the largest percentage of optimal and suitable areas compared to the other three countries. Secondly, this study also conducted a comparison analysis between bio-geophysical suitability and Normalized Difference Vegetation Index (NDVI) over 20 years, and the results show good consistency between the two indicators, with the highest R2 value being 0.61. Thirdly, the comparison between bio-geophysical suitability and production data in two villages in Japan demonstrates that an increase in suitability from 0.28 to 0.32 indicates a significant increase in production. Production would stay stable even with further increases in suitability. Finally, two case studies with monthly comparisons of bio-geophysical suitability across Japan and East Asia in 2020 provide an effective benchmark for determining optimal sowing and harvest times. This study’s results can provide important insights into the trade of Chinese cabbage and support the development of agricultural insurance programs both for farmers and insurance companies. Furthermore, this approach may also be applicable for the assessment of the suitability of other crops.

Soil acidity threatens food production in the tropics. The effect of increasing ammonium-based fertilizer (INF) on soil pH was assessed in sub-Saharan Africa (SSA). A total of 9043 soil data from Africa soil information services, past INF use, and two future scenarios of INF use (business as usual (BAU) and equitable diet (EqD)) were used to determine soil pH variations from 1980 to 2022 and to predict soil PH variations from 2022 to 2050. Random forest and extreme gradient boosting algorithms and soil-forming factor covariates were used for the spatio-temporal soil pH predictions. Topsoil acidification was shown to be significant, with mean annual decrements of 0.014, 0.024, and 0.048 from 1980 to 2022, 2022 to 2050 (BAU), and 2022 to 2050 (EqD), respectively. Over the past 42 years, croplands with soil pH < 6.5 have declined significantly, and soil acidification is predicted to become severe by 2050 in the BAU and EqD scenarios. This was indicated by a predicted 3% increase in croplands at risk of aluminum toxicity (soil pH < 5.5) from 66 × 106 ha in 2022 to 78.5 × 106 ha in 2050. The drivers of the spatial variations in the soil pH between 1980 and 2050 were the MAP, basic cation, clay content, SOC, and nitrogen fertilizers. The evaluation metrics of the 10-fold cross-validation showed that the root mean squared errors (RMSEs) of the soil pH from 1980 to 2022, as well as the predicted soil PH from 2022 to 2050 (BAU) and 2022 to 2050 (EqD), were 0.53 pH units, 0.54 pH units, and 0.56 pH units, respectively, with coefficients of determination (R2) of 0.63, 0.64, and 0.66. The findings of this study can be used for the establishment of management strategies for increasing INF use in acidic soils.

Acidic soils (pH < 5.5) cover roughly 30% of Sub-Saharan Africa. Low nitrogen fertilizer application (15 kg N ha−1 yr−1) has no effect on soil acidification in Sub-Saharan Africa (SSA). However, the effect of optimized fertilizer use on soil acidification (H+) in SSA crops remains unknown. This study intended to predict the spatial variation of H+ caused by optimized fertilizer use using data from 5782 field trials in SSA cropland. We used ensemble machine learning to predict spatial variation (H+) after measuring the inputs and outputs of major elements and their effect on H+ production. The results revealed that H+ ranged spatially from 0 to 16 keq H+ ha−1 yr−1. The most protons (H+) were produced by cassava, banana, and Irish potatoes systems with 12.0, 9.8, and 8.9 keq H+ ha−1 yr−1, respectively. The results of the 10-fold cross validation for the soil acidification model were a coefficient of determination (R2) of 0.6, a root mean square error (RMSE) of 2.1, and a mean absolute error (MAE) of 1.4. Net basic cation loss drives soil acidification under optimized fertilizer application and climate covariates had a higher relative importance than other covariates. Digital soil mapping can produce soil acidification maps for sustainable land use and management plans.

Perfluorobutane sulfonate (PFBS) has been found in increasing concentrations in the environment. However, its effect on litter decomposition in soils is still unclear. Therefore, the effect of PFBS on the decomposition of various litter types was tested, as well as on selected aspects of soil quality. Soil samples were treated with different concentrations of PFBS (0, 1, and 10 µg g–1) and five organic litter materials were used with various C:N ratios. A soil microcosm experiment was performed at 20 °C for 6 weeks. Litter decomposition, soil respiration, enzyme activities, soil pH, water-stable aggregates (WSA), and soil total C and N contents were measured. PFBS treatments were observed to have negligible effects on litter decomposition as well as on other soil properties. This means that in the concentration range examined, this substance has no observable effects on the key soil parameters examined. The present result was inconsistent with the findings of a previous study with similar experimental microcosms but different soils. This study suggests that the effects of PFBS may be less pronounced in the tested soil, but it cannot be concluded that PFBS is harmless in soil ecosystems. A wider range of soil types and PFBS levels should be tested in future studies.

This paper examines the effect of mineral fertilizers and waste lignite, the latter applied to the preceding crop, on the enzymatic activity of soil. The research was conducted between 2014 and 2016 at the Agricultural Experimental Station of the Siedlce University of Natural Sciences and Humanities in Zawady (Poland). The following treatment combinations were involved: 1—control; 2—NPKMgS; 3—NPKMgS + 20 N; 4—NPKMgS + 40 N; 5—NPKMgS + 60 N. Three varieties of maize grown for silage constituted the second research factor. Mineral fertilizers were applied at the following doses (pre-sowing): N-100, P-35, K-125, Mg-12 and S-14 kg ha−1. Nitrogen was additionally applied as top dressing with 3, 4, and 5 treatment combinations at 20, 40, and 60 kg ha−1. Waste lignite was applied to the preceding crop on two plots (3 and 4), in 1 and 5 t ha−1 doses. In the subsequent years, the significantly highest content of soil organic carbon was recorded on the NPKMgS + 60 N plot (1.12%; 0.98% and 1.16%). With 49.25 and 51.95 mg NH4-N h–1 kg–1 DM, urease activity in the soil treated with NPKMgS + 20 N and NPKMgS + 40 N was 56.95% and 65.55% higher than in the control plot soil. Throughout the experimental years, acid phosphatase activity did not vary much and amounted to 3.51–3.53 mmol PNP h–1 kg–1 DM. Mineral fertilizers significantly increased the activity of alkaline phosphatase and dehydrogenases in relation to the control. To ensure the high enzymatic activity of the soil and a high biochemical index of soil fertility, pre-sowing fertilizers at the level of 100 kg N, 35 kg P, 125 kg K, 12 kg Mg, and 14 kg S per hectare and top dressing of 20 kg N or 40 kg N per hectare are recommended. At the same time, it is advisable to use 1 t ha–1 or 5 t ha–1 of waste lignite of low energy value on the preceding crop.

The abundance and distribution of soil microbial populations, i.e., microbial diversity is widely promoted as a key tenant of sustainable agricultural practices and/or soil health. A common approach to describing microbial diversity is phylogenetic analysis with high-throughput sequencing of microbial DNA. However, owing to the tremendous amounts of data generated, a continuing effort is required to better assess the effects of agricultural management systems on soil microbial diversity. Here, we report on the combined effects of management systems on bacterial and fungal diversity in a loessal agricultural soil located in north-central Mississippi, USA. Amplicon sequencing was performed using 16S rRNA-gene and ITS2 from soil samples collected from a three-year study with combinations of maize-soybean crop rotation, tillage practices, and winter vegetative covers. Differences were found in microbial fungal β-diversity among the management systems, with distinct clustering patterns for no-tillage combined with either winter weeds or bare-fallow. Management systems showed a significant influence on soil pH and bulk density, which were positively correlated with fungal community composition. Developments in the description and interpretation of soil microbial diversity will contribute to a more accurate understanding of its role in the various functions and processes important to agricultural soil management.

Integrating urban agriculture with aquaculture can reduce the use and cost of water, competition for water, chemical fertilizers, and environmental impact of discharging nutrient-rich agricultural water into fresh and saltwater bodies. In addition, aquaculture in cities can directly benefit human health by providing a local source of lean protein. Despite the potential advantages, few studies have demonstrated the feasibility and production advantages of using aquaculture wastewater to fertigate specialty crops in an urban environment. Therefore, we grew four spring crops (bok choy, tatsoi, radish, turnip) and two fall crops (pole beans, sugar snap peas) in nutrient-rich effluent from fish aquaculture versus well or municipal water to evaluate whether the effluent improved soil fertility and crop production. The fish effluent resulted in changes to the soil through an increase in pH and potassium and to crop production through a 9.1% increase in the number of pole beans (mass of beans also trended toward significance). The soils we used were relatively nutrient-rich prior to the application of the fish effluent, which may be responsible for the limited impact, and differences may be more apparent in acidic and nutrient-poor soils or when fertigation is used over a longer duration.

Remote sensing data comprise a valuable information source for many ecological landscape studies that may be under-utilized because of an overwhelming amount of processing methods and derived variables. These complexities, combined with a scarcity of quality control studies, make the selection of appropriate remote sensed variables challenging. Quality control studies are necessary to evaluate the predictive power of remote sensing data and also to develop parsimonious models underpinned by functional variables, i.e., cause rather than solely correlation. Cause-based models yield superior model transferability across different landscapes and ecological settings. We propose two basic guidelines for conducting such quality control studies that increase transferability and predictive power. The first is to favor predictors that are causally related to the response. The second is to include additional variables controlling variation in the property of interest and testing for optimum processing method and/or scale. Here, we evaluated these principles in predicting ground vegetation cover, soil moisture and pH under challenging conditions with forest canopies hindering direct remote sensing of the ground. Our model using lidar data combined with natural resource maps explained most of the observed variation in soil pH and moisture, and somewhat less variation of ground vegetation cover. Soil pH was best predicted by topographic position, sediment type and site index (R2 = 0.90). Soil moisture was best predicted by topographic position, radiation load, sediment type and site index (R2 = 0.83). The best model for predicting ground vegetation cover was a combination of lidar-based estimates for light availability below canopy and forest type, including an interaction between these two variables (R2 = 0.65).

Soil acidity is one of the major soil-degradation events throughout the world, and the long-term application of nitrogenous fertilizers is thought to be a main cause of soil acidity. In the present experiment, we collected soil and tea (Camellia sinensis L.) leaf samples from five representative tea gardens in Bangladesh and evaluated soil nutrient pools and biochemical properties of tea leaves. The results showed that there was a negative relationship between soil pH and the amount of applied nitrogenous fertilizers. Moreover, continuous application of traditional fertilizers over twenty-five years promoted not only the deficiency of phosphorus (P) and mineral-based cations, such as potassium (K+), calcium (Ca2+), and magnesium (Mg2+), but also increased manganese (Mn2+) and aluminum (Al3+) toxicity in soils, which suppressed the yield and quality of tea. Crucially, tea leaf production remained almost similar (average 1079.77 kg ha−1) from 1995 to 2015, while the application doses of urea, TSP, and MoP increased by 24.69%, 18.92%, and 16.67%, respectively, in garden soils. However, the pH value of soil declined up to 24% from 1992 to 2020 in the tested gardens. Consequently, the availability of K+, P, Ca2+, and Mg2+ decreased by 56%, 25%, 55%, and 49%, respectively, in those tea garden soils. In addition, the quality of tea leaves was severely affected, as evident by the reduced levels of total flavonoids, polyphenols, soluble solids, vitamin C, vitamin B1, and vitamin B2. Moreover, free-radical scavenging activity (DPPH), caffeine, and tannin concentration were increased in tea leaves, which indicated that tea plants were potentially being stressed. Therefore, we study concluded that long-term application of traditional nitrogenous fertilizers can be an important regulator of lowering garden soil pH, which reduces native soil nutrient pools and thereby the yield and quality of tea leaves.

Increasing salinity undermines soil fertility and imposes great threats to soil ecosystem productivity and ecological sustainability. Microbes with the ability to adapt to environmental adversity have gained increasing attention for maintenance and restoration of the salt-affected soil ecosystem structure and functioning; however, the characterization of microbial communities in saline–sodic soils remains limited. This study characterized the bacterial community composition and diversity in saline–sodic soils along a latitude gradient across Northeast China, aiming to reveal the mechanism of physicochemical and geographic characteristics shaping the soil bacterial communities. Our results showed that the bacterial community composition and diversity were significantly impacted by soil pH, electrical conductivity, Na+, K+, Cl−, and CO32−. Significant differences in bacterial diversity were revealed along the latitude gradient, and the soil factors accounted for 58.58% of the total variations in bacterial community composition. Proteobacteria, Actinobacteria, Gemmatimonadetes, Chloroflexi, and Bacteroidetes were dominant across all samples. Actinobacteria and Gemmatimonadetes were significantly enriched in high soil sodicity and salinity, while Acidobacteria and Proteobacteria were suppressed by high pH and salt stress in the saline–sodic soils. Increase in soil pH and salinity significantly decreased bacterial species richness and diversity. Community composition analysis indicated that bacterial taxonomic groups (e.g., Bacillus, Egicoccus, Truepera, Halomonas, and Nitrolancea) that may adapt well to high salinity were greatly enriched in the examined soils. The findings collectively evidenced that bacterial community composition and diversity in a broad biographic scale were determined by niche-based environmental characteristics and biotic interactions. The profiling of the soil bacterial communities along the latitude gradient will also provide a basis for a better understanding of the salt-affected soil ecosystem functioning and restoration of these soil ecosystems.

This study was carried out to investigate effects of subsoiling on the diversity and composition of the bacterial community in a wheat–maize rotation field in the Guanzhong area of Shaanxi Province, China. After the wheat harvest, surface soil samples were collected under two tillage methods (single rotary tillage (RT) and subsoiling + rotary tillage (ST)) to perform high-throughput sequencing and bioinformatics analysis. Soil properties and root length density (RLD) of winter wheat at booting and flowering stages were also studied. Results showed that ST treatment significantly raised the water storage, organic carbon and total nitrogen contents of deep soil (>40 cm), and notably increased the total soil pH, ammonium nitrogen content and RLD in the tillage layer from 0–70 cm at booting stage and 0~100 cm at flowering stage, but the residual nitrate nitrogen significantly decreased by 17.74%. Compared with RT, soil bacterial richness and diversity in the 10~20 cm layer of ST treatment showed a significantly decreased trend. The relative abundances of GAL15, Actinobacteria, Nitrospirae, Rhizobiales, Burkholderiales, Pseudomonas and Serratia in the 10–20 cm layer were remarkably increased in ST. Principal Component Analysis (PCA) and Redundancy Analysis (RDA) results showed that surface soil pH, ammonium nitrogen and nitrate nitrogen contents have the strongest effect on the bacterial structure. In addition, there were positive correlations between the RLD and the relative abundances of Rhizobiales, Burkholderiales, Pseudomonas and the ammonium nitrogen content. In conclusion, although subsoiling was not conducive to improving soil bacterial community richness and diversity, it significantly increased soil beneficial bacteria (biological nitrogen-fixing bacteria, ammonifying bacteria, nitrobacteria) abundances, reduced the nitrogen loss caused by denitrifying bacteria, promoted earlier root development and improved the plant utilization ratio of soil nutrients.

Bryophytes are commonly used in biomonitoring heavy metal pollution, whereas the bioindicative value of bryophyte communities is a less known issue. The aim of the present study is to recognize the utility of the bryophyte community’s structure in the assessment of soil condition in heavy metal-polluted, dry grasslands. The study plots are examined with respect to bryophytes; vascular plants; concentrations of Zn, Pb, Cd, and As in the soil; total nitrogen and organic carbon content in the soil; and soil pH. The results show that both bryophyte species richness and composition greatly depend on soil chemical characteristics, including heavy-metal pollution levels and soil pH. Three groups of species are distinguished: (1) species sensitive to pollution growing on acidic soils, (2) nonspecific species inhabiting a wide spectrum of heavy metal-polluted sites, and (3) species preferring polluted and alkaline soils. Our study reveals a gradual replacement of the bryophyte species alongside increasing soil pollution and alkalinity. This proves that bryophytes are highly responsive to soil factors and the changes in bryophyte composition may indicate the soil condition of a certain site. Furthermore, high concentrations of heavy metals in the soil and an alkaline pH positively affect bryophyte species richness. Consequently, such sites could be considered as biodiversity hotspots for terrestrial bryophytes in post-industrial landscapes.

Soil fungi play an integral and essential role in maintaining soil ecosystem functions. The understanding of altitude variations and their drivers of soil fungal community composition and diversity remains relatively unclear. Mountains provide an open, natural platform for studying how the soil fungal community responds to climatic variability at a short altitude distance. Using the Illumina MiSeq high-throughput sequencing technique, we examined soil fungal community composition and diversity among seven vegetation types (dry valley shrub, valley-mountain ecotone broadleaved mixed forest, subalpine broadleaved mixed forest, subalpine coniferous-broadleaved mixed forest, subalpine coniferous forest, alpine shrub meadow, alpine meadow) along a 2582 m altitude gradient in the alpine–gorge region on the eastern Qinghai–Tibetan Plateau. Ascomycota (47.72%), Basidiomycota (36.58%), and Mortierellomycota (12.14%) were the top three soil fungal dominant phyla in all samples. Soil fungal community composition differed significantly among the seven vegetation types along altitude gradients. The α-diversity of soil total fungi and symbiotic fungi had a distinct hollow pattern, while saprophytic fungi and pathogenic fungi showed no obvious pattern along altitude gradients. The β-diversity of soil total fungi, symbiotic fungi, saprophytic fungi, and pathogenic fungi was derived mainly from species turnover processes and exhibited a significant altitude distance-decay pattern. Soil properties explained 31.27−34.91% of variation in soil fungal (total and trophic modes) community composition along altitude gradients, and the effects of soil nutrients on fungal community composition varied by trophic modes. Soil pH was the main factor affecting α-diversity of soil fungi along altitude gradients. The β-diversity and turnover components of soil total fungi and saprophytic fungi were affected by soil properties and geographic distance, while those of symbiotic fungi and pathogenic fungi were affected only by soil properties. This study deepens our knowledge regarding altitude variations and their drivers of soil fungal community composition and diversity, and confirms that the effects of soil properties on soil fungal community composition and diversity vary by trophic modes along altitude gradients in the alpine–gorge region.

Knowledge of the long-term complex relationship between soils, crops, and management practices, such as conservation agriculture, is critical in developing nutrient management strategies to optimise crop yields. This study examined the concentration, and the distribution of, soil micronutrients along the soil profile (0–10, 10–20, and 20–30 cm depths) under different tillage practices: no-till (NT), rotational tillage (RT), and conventional tillage (CT), and nitrogen fertilizer application rates (0, 100, 200 kg/ha) in a semi-arid environment after 17 years of implementation of the trial. The results found the lowest concentration (p < 0.05) of copper (Cu) (1.254 mg/kg) and iron (Fe) (22.671 mg/kg) in CT compared to NT [Cu (1.447 mg/kg), Fe (41,156 mg/kg)] and RT [Cu (2.389 mg/kg), Fe (120,437 mg/kg)] treatments. This correlated with the lower soil pH in NT compared to CT treatment, and slightly higher (p > 0.05) under NT (1.782 mg/g) compared to RT (1.715 mg/g) and CT (1.750 mg/g). There were no differences (p > 0.05) in zinc (Zn) in NT (2.856 mg/kg) and RT (2.782 mg/kg) but CT (2.010 mg/kg) treatment was significantly (p < 0.05) lower compared to these treatments. Manganese (Mn) also followed a similar trend whereby CT still had the lowest concentration (p < 0.05) of Mn (8.01 mg/kg) compared to RT (10.71 mg/kg) and NT (11.98 mg/kg). The concentration of Mn, Zn, and Fe was found to be similar (p > 0.05) with an increase in sampling depths. On the other hand, Cu was found to be different (p < 0.05) at different sampling depths. Manganese (10.46 mg/kg) and Soil Organic Carbon (SOC) (2.026 mg/g) were found to be concentrated near the 0–10 cm soil surface depth while Zn (2.558 mg/kg), Fe (66,217 mg/kg) and Cu (1.867 mg/kg) were more at the 20–30 cm depth in reduced tillage treatments. The results also showed no differences (p > 0.05) in the concentration of Cu, Mn, and Zn at different levels of nitrogen fertilizer under all tillage treatments. It was concluded that NT and rational tillage with mulch, favoured the availability of micronutrients (Cu, Mn, Fe, and Zn) in the studied cropping system.

Spatial variation of soil pH is important for the evaluation of environmental quality. A reasonable number of sampling points has an important meaning for accurate quantitative expression on spatial distribution of soil pH and resource savings. Based on the grid distribution point method, 908, 797, 700, 594, 499, 398, 299, 200, 149, 100, 75 and 50 sampling points, which were randomly selected from 908 sampling points, constituted 12 sample sets. Semi-variance structure analysis was carried out for different point sets, and ordinary Kriging was used for spatial prediction and accuracy verification, and the influence of different sampling points on spatial variation of soil pH was discussed. The results show that the pH value in Kenli County (China) was generally between 7.8 and 8.1, and the soil was alkaline. Semi-variance models fitted by different point sets could reflect the spatial structure characteristics of soil pH with accuracy. With a decrease in the number of sampling points, the Sill value of sample set increased, and the spatial autocorrelation gradually weakened. Considering the prediction accuracy, spatial distribution and investigation cost, a number of sampling points greater than or equal to 150 could satisfy the spatial variation expression of soil pH at the county level in the Yellow River Delta. This is equivalent to taking at least 107 sampling points per 1000 km2. The results in this study are applicable to areas with similar environmental and soil conditions as the Yellow River Delta, and have reference significance for these areas.

Appropriate fertilization can enhance forest productivity by maintaining soil fertility and improving the structure of the bacterial community. However, there is still uncertainty surrounding the effects of combined application of organic and inorganic fertilizers on soil nutrient status and bacterial community structure. A fertilization experiment was set up in an eight-year-old teak plantation with five treatments involved: mixed organic and NPK compound fertilizers (OCF), mixed organic and phosphorus fertilizers (OPF), mixed organic, NPK and phosphorus fertilizers (OCPF), mixed NPK and phosphorus fertilizers (CPF) and no fertilization (CK). Soil chemical properties and bacterial communities were investigated, and the co-occurrence pattern of the bacterial community under different fertilization treatments was compared. The results showed that the contents of soil organic matter and nitrate nitrogen, and the soil pH values were the highest after OCPF treatment, which were 20.39%, 90.91% and 8.16% higher than CK, respectively. The richness and diversity of bacteria underwent no obvious changes, but the structure of the soil’s bacterial community was significantly altered by fertilization. Of the dominant bacteria taxa, the relative abundance increased for Gemmatimonadetes, Myxococcota, ADurb.Bin063-13 and Candidatus_Koribacter, and decreased for Chloroflexi, Proteobacteria, JG30-KF-AS9 and Acidothermus under OCPF treatment in comparison to CK. The number of nodes and edges, the average degree and the network density of bacterial community co-occurrence networks were the greatest in OCPF treatment, indicating that application of OCPF could make the network structure of soil bacteria more stable and complex. Moreover, soil pH and organic matter were significantly correlated with bacterial community structure and were considered the main influencing factors. These findings highlight that the combined application of organic, NPK and phosphorus fertilizers is highly beneficial for improving soil quality and optimizing bacterial community structure in teak plantations.

Soil acidification has become increasingly serious due to anthropogenic activities (e.g., fertilization) throughout the world. Examining the effects of soil acidification on bacterial and fungal communities in acidic crop soils provides valuable insights for revealing the potential role of microbes in soil quality and crop yield. Here, a total of 18 samples with pH varied from 4 to 7 were collected from agricultural regions in the Jiaodong Peninsula, Shandong Province, China. High-throughput sequencing analysis was used to determine the composition and diversity of the bacterial and fungal communities. The results revealed that the α-diversity of the bacterial community was significantly decreased as the soil acidification increased, while that of fungal communities exhibited little response to soil acidification, thus indicating that bacteria rather than fungi respond sensitively to soil acidification. Principal component analysis (PCA) and canonical correlations analysis (CCA) further corroborated that pH is an essential predictor for controlling the distribution of microbial communities, and it also could alter other exchangeable base cation (e.g., EH+, EAl3+, EK+, ENa+, ECa2+, and EMg2+) contents to further drive the microbial community patterns.

Three phosphorus (P) fertilizer fractions recycled from biogas digestates were tested alone and in combination for their efficiency in two agricultural surface soils with different pH: a silty sandy loam and a clay loam. The experiments were carried out in pots under greenhouse conditions, using mineral triple superphosphate (TSP) as a reference. Maize was cultivated for 50 days, followed by ryegrass cultivation for an additional 84 days in the same soil, without additional fertilization. The variables investigated were above-ground plant biomass production, plant phosphorus concentration and content, and plant available phosphorus concentration in soil. The dry matter (DM) yield of maize was increased by the organic P fertilizers equal to or more than TSP in both soils. In the neutral soil, biomass was almost doubled compared to TSP when using one of the fractions (Struvite containing P-Salt) alone or in combination with dried solid fractions. P concentration in maize cultivated in the neutral soil was not significantly different between the P fertilization treatments. However, associated with biomass increase, the total P content in maize plants was equal to or higher than that with TSP. In the acidic soil, P concentration and total P content in maize plants, as well as the calcium-acetate-lactate extractable P (CAL-P) concentration in soil, were equal to or even higher than TSP. Ryegrass DM yield was unaffected by all P fertilizers, independent of the soil, although P concentration and total P content increased in the acidic soil with all fertilizers. Our results show that recycled P fertilizers from biogas digestates are effective P fertilizer alternatives to mineral TSP for maize cultivation under acidic and neutral soil conditions. The lack of growth effects in ryegrass indicates that recycled P fertilizers do not require changes in weed control. On the other hand, P extraction by ryegrass in overfertilized acidic soils as an option for soil remediation also works in soils fertilized with biogas digestate fractions.

Hay meadows are secondary grasslands maintained by mowing, and their ecological importance resides in the inherent biodiversity and carbon stocking. We investigated the plant community and soil properties of a sub humid acid grassland near the Fucecchio marshes (Italy), managed as a hay meadow, mowed once a year, and not fertilized. Part of the meadow had been abandoned for three years. We analysed the soil properties (i.e., organic carbon and total nitrogen content, available phosphorus, pH, cation-exchange capacity, texture, and conductibility) and the plant community structure (composition, functionality, and species richness) of the two sides of the meadow (mowed and abandoned). Our aim was to highlight the changes in soil properties and vegetation community, and to find out to what extent abandonment can affect those dynamics. Our results showed that after short-term abandonment, soil pH, C and N increased; litter biomass and perennial forbs increased; and annual forbs decreased. New species colonising after abandonment, thus enriching the flora, may keep spreading and eventually hinder the growth of the specialists if mowing is not resumed. Certain valuable meadow habitats need constant human intervention to maintain their peculiar vegetation, most especially if they are a buffer zone in the proximity of natural protected areas.

Tea components (tea polyphenols, catechins, free amino acids, and caffeine) are the key factors affecting the quality of green tea. This study aimed to relate key biochemical substances in tea to soil nutrient composition and the effectiveness of fertilization. Seventy tea samples and their corresponding plantation soil were randomly collected from Xinyang City, China. The catechins, free amino acids, and caffeine in tea were examined, as well as the soil pH, nitrate (NO3--N), ammonium (NH4+-N), available phosphorus (AP), available potassium (AK), and soil organic matter (SOM). The ordinary kriging was employed to visualize the spatial variation characteristic by ArcGIS. A quadratic regression model was used to analyze the effects of the soil environment on the tea. The results showed that the soil pH of the study area was suitable for cultivating tea plants. The relationship between soil pH and tea polyphenols and catechins presented the U-shape curve, whereas the soil pH and NH4+-N and the free amino acids, the soil pH, and caffeine presented the inverted U-shape curve. Soil management measures could be implemented to control the soil environment for improving the tea quality. The combination of the macro metrological model with individual experimentation could help to analyze the detailed influence mechanisms of environmental factors on plant physiological processes.

Reductive Soil Disinfestation (RSD) is a good method which can restore degraded greenhouse soil and effectively inactivate soil-borne pathogens. However, the approach needs to be optimized in order to facilitate its practical application in various regions. In the present work, we investigated the effect of soil water content (60% water holding capacity (WHC), 100% WHC and continuous flooding) and maize straw application rates (0, 5, 10, and 20 g kg−1 soil) on the improvement of soil properties and suppression of soil-borne pathogens (Fusarium oxysporum, Pythium and Phytophthora). The results showed that increasing the soil water content and maize straw application rate accelerated the removal of excess sulfate and nitrate in the soil and elevated the soil pH. Elevating the water content and maize straw application rate also produced much more organic acids, which could strongly inhibit soil-borne pathogens. Soil properties were improved significantly after RSD treatment with a maize straw amendment rate of more than 5 g kg−1, regardless of the water content. However, RSD treatments with 60% WHC could not effectively inactivate soil-borne pathogens and even stimulated their growth by increasing the maize application rate. RSD treatments of both 100% WHC and continuous flooding could inactivate soil-borne pathogens and increase the pathogens mortality indicated by cultural cells relatively effectively. The inhibited pathogens were significantly increased with the increasing maize application rate from 5 g kg−1 to 10 g kg−1, but were not further increased from 10 g kg−1 to 20 g kg−1. A further increased mortality of F. oxysporum, indicated by gene copies, was also observed when the soil water content and maize straw application rate were increased. Therefore, RSD treatment with 60% WHC could improve soil properties significantly, whereas irrigation with 100% WHC or continuous flooding was a necessity for effective soil-borne pathogens suppression. Holding 100% WHC and applicating maize straw at 10 g kg−1 soil were optimum conditions for RSD field operation to restore degraded greenhouse soil.

If available to farmers, potatoes represent a crop classically fertilized with farmyard manure in the Czech Republic. At the same time, potatoes are a crop sensitive to soil–climate conditions. We evaluated the effect of cattle manure (FYM), manure and mineral nitrogen (FYM + N1, FYM + N2), manure and mineral fertilizers (FYM + N1PK, FYM + N2PK, FYM + N3PK) application and the effect of three soil-climatic conditions (Caslav—maize production area with degraded Chernozem, Ivanovice—maize production area with Chernozem, Lukavec—potatoes production area with Cambisol) over four years (2016–2019) on potatoes yield and soil chemical properties. Of all the factors, yields were most affected by location. Lukavec provided the highest average yields (37.2 t ha−1), followed by Ivanovice (23.5 t ha−1) and Caslav (15.5 t ha−1). The second most important factor was the climatic conditions of the year. Fertilization was the third most important parameter. FYM significantly increased yields compared to Control, but applied alone cannot cover the needs of potatoes. Similarly, the application of FYM and N increases yields, but for the highest yields, it is best to apply FYM + NPK (80 kg ha−1 N). Co-application of FYM and mineral N fertilizers mitigates the negative impact of mineral N on soil pH.

Recently, an increasing interest in such fertilizers and fertilization methods which not only directly supply nutrients to plants, but also stimulate soil bioactivity is noted. Their effect on both soil microbiota and forage plants has not been fully recognized. The aim of the study was to investigate the combined effect of forage plant mixture type and mineral fertilizers (NPK) with biostimulants based on a marine algae extracts on the botanical composition, yield, the structure of selected taxonomic and trophic groups of soil microorganisms, and the soil enzymatic activity. During the years 2018–2019 a field experiment established in split-plot design with two different forage plant mixtures, as a first factor, and different fertilization basing on mineral fertilizers amended with biostimulants, as a second factor was conducted. Two types of forage mixtures of sown species were used: grass mixture (GM) and legume-grass mixture (LGM). Every year the following biostimulants were applied: N-14, PinKstart, Physiostart, Physioactive and they were compared with standard NPK fertilisation and no fertilisation as a control. The reaction of forage plant mixtures on applied fertilisation was different. The intensive development of grass species, mainly Lolium perenne, at the expense of Trifolium repens share in LGM was observed. In GM sward dominated Dactylis glomerata. A beneficial effects of biostimulants’ application on the biomass yields of both grass mixtures was observed. The systematic soil acidification and a decrease of soil enzymatic activity in result of applied fertilization, except NPK + Physioactive treatment (calcium fertilizer containing 76% calcium carbonate), was noted. Soil reaction to applied fertilisation was dependent on the botanical composition of the sward. The counts of microorganisms in the soil under LGM were almost two times higher than in the soil under GM. The most effective, in reducing the negative effect of nitrogen mineral fertilization on the pH of soil, was fertilization with NPK + Physioactiv.

This research was conducted to evaluate the trends of the extractable micronutrients boron (B), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) in soils differing in textures and collected before tobacco cultivation, and in after unfertilized and fertilized (N10P18K24 and CAN 27%) plots. The soils and tobacco leaves were assessed on the contents of the micronutrients after unfertilized and fertilized tobacco cultivation. In soils, tobacco cultivation with fertilization increased the extractable Cu, Fe, Mn, and Zn by 0.10, 11.03, 8.86, and 0.08 mg kg−1, respectively, but decreased the extractable B by 0.04 mg kg−1. The effects of fertilization increased the extractable Cu, Fe, Mn, and Zn by 0.14, 14.29, 9.83, and 0.24 mg kg−1, respectively, but decreased B by 0.08 mg kg−1. The combination effects of tobacco cultivation and fertilization increased the extractable Cu, Fe, Mn, and Zn by 0.24, 25.32, 18.69, and 0.32 mg kg−1, respectively, but decreased the extractable B by 0.12 mg kg−1. The results revealed that the solubility of the extractable Zn, Mn, Cu, and Fe in soils were increased by both tobacco and fertilization, but the extractable B was decreased. The fertilization of the studied soils with NPK + CAN fertilizers significantly increased the concentration of the extractable micronutrients in tobacco leaves. Based on the findings of this study, further research must be conducted to investigate the effects of tobacco cultivation on soil health and fertility beyond considering only soil pH, SOC, micronutrients, and macronutrients. These studies should include the relationship between soil fertility (pH, texture, CEC, base saturation, etc.), micronutrients, and agronomic practices on the effect of tobacco cultivation on the extractability of B, Cu, Fe, Mn, and Zn.

Variations in soil pH have been shown to affect mesotrione adsorption, which in turn, may have an impact on crop susceptibility. Therefore, a greenhouse experiment was conducted to evaluate the effect of simulated mesotrione residues on pea crop grown in the typical agricultural soil (gleysol) of north-western Croatia. The soil pH was manipulated to obtain neutral (pH 7.0) and acidic (pH 5.0) values. Simulated mesotrione residues were 1.1, 2.3, 4.5, 9.0, 18, 36 and 72 g a.i. ha−1. Crop visual injuries as well as reductions in chlorophyll fluorescence and aboveground dry biomass were higher at pH 7.0 than at pH 5.0. With increasing mesotrione residues, the reductions in chlorophyll fluorescence ranged from 38.8% to 89.7% at pH 5.0 and from 63.7% to 99.3% at pH 7.0. Compared to chlorophyll fluorescence, the reductions in dry biomass were smaller and ranged from 49.2% to 96.8% at pH 7.0 and from 32.0% to 82.6% at pH 5.0 for the mesotrione residues from 1.1 to 72 g a.i. ha−1. These results indicate that soil pH is an important factor determining the susceptibility of pea crop to simulated mesotrione residues.

Soil acidity is one of the main constraints to crop production worldwide. In Ethiopia, the problem of soil acidity has been increasing. Currently, more than 40% of cultivated land in the country has a soil pH < 5.5. Recently, bacterial wilt (caused by Ralstonia solanacearum) has become a serious problem, reaching epidemic levels in some of the major potato growing districts in the country. However, it is currently unknown if the current outbreak of bacterial wilt in potato production is associated with soil acidification or not. To examine the association between bacterial wilt and soil acidification, we conducted a field survey and field experiments and detected and characterised R. solanacearum strains. The study showed that 50% of potato fields were very strongly acidic (pH 4.5–5.0) and bacterial wilt incidence was higher in potato fields with low soil pH. The field experiments indicated that lime application significantly increased soil pH (p < 0.001) and reduced bacterial wilt incidence (p < 0.001). The more lime was applied, the stronger the positive effect on soil pH and the stronger the reduction in bacterial wilt incidence. Bacterial wilt incidence was on average 10.8% under 12 t/ha lime application, while it was about 40% in control plots (without lime) after 90 days. All R. solanacearum strains isolated from the symptomatic potato plants were Phylotype II. Our findings show that the current outbreak of bacterial wilt in Ethiopia is associated with soil acidification. They add to the understanding of the risk factors for bacterial wilt in potato. Aside from farm hygiene, sanitation and cultural practices, addressing soil acidification using lime needs to be considered as an additional component of an integrated package to deal with bacterial wilt in potato under acidic soil conditions.

Adoption of crop residue amendments has been increasingly recommended as an effective management practice for mitigating greenhouse gas emissions while enhancing soil fertility, thereby increasing crop production. However, the effect of biochar and straw on nitrous oxide (N2O) and methane (CH4) emissions in soils of differing pH remains poorly understood. Three treatments (control (i.e., no amendment), maize straw, and biochar derived from maize straw) were therefore established separately in soils with different pH levels, classified as follows: acidic, neutral, and alkaline. N2O and CH4 were investigated using a static chamber–gas chromatography system during 57 days of a mesocosm study. The results showed that cumulative N2O emissions were significantly higher in acidic soils than in other experimental soils, with the values ranging from 7.48 to 11.3 kg N ha−1, while CH4 fluxes ranged from 0.060 to 0.089 kg C ha−1, with inconclusive results. However, a weak negative correlation was observed between log N2O and log NO3-N in acidic soil with either biochar or straw, while the same parameters with CH4 showed a moderate negative correlation, suggesting a likelihood that these amendments could mitigate GHGs as a result of the NO3-N increase in acidic soils. It is also possible, given the alkaline nature of the biochar, that incorporation had a significant buffer effect on soil acidity, effectively increasing soil pH by >0.5 pH units. Our findings suggest that for the rates of application for biochar and straw used in this study, the magnitude of reductions in the emissions of N2O and CH4 are dependent in part on initial soil pH.

Landscape scale assessment of temporal variations in soil organic carbon (SOC) contents and soil pH and the implications for long-term agricultural sustainability was determined using legacy datasets collected over two periods separated by 20 years: the 1990s and 2010s. Soil data on SOC and pH were categorized according to the prevailing land types (based on inundation as highland (HL), medium highland (MHL), and medium lowland (MLL)), and physiographic types (i.e., Himalayan Piedmont plain, Tista Floodplain and Barind tract/Terrace) to determine which variable or combination of variables was more influential in spatial and temporal changes of these properties. SOC contents in the physiographic types were generally found to be low, varying between 8 to 12 g/kg. While, SOC contents were significantly higher in MHL and MLL compared with HL that experienced less inundation. The change in SOC contents over 20 years was significant with a 14.5% increase of SOC. There was a greater influence of land type compared with physiography on SOC contents over time. Inundation land types and associated cropping intensity were considered likely to influence SOC of soils under rice-based cropping systems. Furthermore, the levels of soil pH decreased by 0.5 units over 20 years with an approximately 50% increase in soils within a pH category of 4.6–5.5. The majority of soil pH results shift from slightly acidic to strongly acidic in the intervening 20-year period between samplings. Soil acidification is potentially a combination of inefficient and excess use of ammonium-based fertilizers with higher application rates and low input from residues. We conclude that acidification may continue with more intensive land use. However, trends in SOC contents over time under certain combinations of physiography and land type either increased slightly or showed a significant loss and in the latter, specifically, the role of land management is not clear. The legacy datasets would be useful for monitoring spatial and temporal soil quality trends at a regional scale, but has limited capacity to capture field level variations in soil properties as data on smallholder cropping practice and management were not collected. Therefore, future research examining the role of management in SOC and pH dynamics at the field-scale would guide the use of fertilizers, crop residue management, and amelioration of acidic soil, to improve the sustainability of rice-based cropping systems in Bangladesh.

Understanding the spatial variation of soil pH is critical for many different stakeholders across different fields of science, because it is a master variable that plays a central role in many soil processes. This study documents the first attempt to map soil pH (1:5 H2O) at high resolution (100 m) in New Zealand. The regression framework used follows the paradigm of digital soil mapping, and a limited number of environmental covariates were selected using variable selection, before calibration of a quantile regression forest model. In order to adapt the outcomes of this work to a wide range of different depth supports, a new approach, which includes depth of sampling as a covariate, is proposed. It relies on data augmentation, a process where virtual observations are drawn from statistical populations constructed using the observed data, based on the top and bottom depth of sampling, and including the uncertainty surrounding the soil pH measurement. A single model can then be calibrated and deployed to estimate pH a various depths. Results showed that the data augmentation routine had a beneficial effect on prediction uncertainties, in particular when reference measurement uncertainties are taken into account. Further testing found that the optimal rate of augmentation for this dataset was 3-fold. Inspection of the final model revealed that the most important variables for predicting soil pH distribution in New Zealand were related to land cover and climate, in particular to soil water balance. The evaluation of this approach on those validation sites set aside before modelling showed very good results (R2=0.65, CCC=0.79, RMSE=0.54), that significantly out-performed existing soil pH information for the country.

Phosphorus (P) is an element that is potatoes require in large amounts. Soil pH is a crucial factor impacting phosphorus availability in potato production. This study was conducted to evaluate the influence of P application rates on the P efficiency for tuber yield, specific gravity, and P uptake. Additionally, the relationship between soil pH and total potato tuber yield was determined. Six rates of P fertilization (0–280 kg P ha−1) were applied at twelve different sites across Northern Maine. Yield parameters were not responsive to P application rates. However, regression analysis showed that soil pH was significantly correlated with total potato tuber yield(R2 = 0.38). Sites with soil pH values < 6 had total tuber yields, marketable tuber yields, tuber numbers per plant, and total tuber mean weights that were all higher than these same parameters at sites with soil pH ≥ 6. All sites with soil pH< 6 showed a highly correlated relationship between P uptake and petiole dry weight (R2 = 0.76). The P application rate of 56 kg P ha−1 was the best at sites with a soil pH < 6, but 0–56 kg P ha−1 was the best at sites with soil pH ≥ 6.