Soil Nutrient Imbalance Research Articles

Effects of alpine meadow degradation on the soil physical and chemical properties in Maqu, China

While alpine meadow degradation presents a significant ecological challenge, research on the complex patterns of soil property changes induced by degradation has been somewhat limited. In this study, we investigated the Maqu alpine meadow, meticulously categorizing it into different grassland types exhibiting varying degrees of degradation based on factors such as vegetation coverage and community, soil characteristics, and landscape features. These classifications included typical grassland, degraded grassland, desertified grassland, and sandy land. In August 2018, we established three quadrats at each sample point and collected soil samples at five depths (surface [0–2 ​cm], 2–5 ​cm, 5–10 ​cm, 10–20 ​cm, and 20–40 ​cm) to analyze soil particle size distribution (PSD) and nutrients content. The results revealed a discernible trend: alpine meadow degradation led to selective loss of nutrient-rich soil fine particles, resulting in significant alterations in soil PSD and nutrients, particularly pronounced in grasslands with low degrees of degradation. Moreover, within a specific range of degradation degree, the clay content in the shallow soil of alpine meadow increased with the degradation degree, but it declined when the degradation degree exceeded a certain threshold. Degradation also disrupted the intricate relationship between soil nutrients, with notable variations in their coupling. This difference was also reflected in the influence of soil physical and chemical properties on soil nutrients, with the explanatory power of each environmental indicator on soil nutrients decreasing significantly with increasing degradation. This study systematically analyzed the variation in soil physical and chemical properties throughout the degradation process, revealing the mechanism of soil nutrient imbalance and decline caused by the degradation process. It provides crucial theoretical foundations and reference points for the preservation and rejuvenation of alpine meadows, enriching the methodology for assessing the impact of grassland degradation.

The influence of soil depth and tree age on soil enzyme activities and stoichiometry in apple orchards

The indispensable role of soil microorganisms in apple orchards, impacting soil quality, nutrient cycling, and crop productivity, cannot be overstated. Nonetheless, as apple trees mature, the potential for soil nutrient imbalances arises, affecting apple growth and yield. Research on how deep soil properties evolve with tree age is limited. Soil samples were gathered from apple orchards of various ages, utilizing the microplate fluorescence method to examine soil enzyme activity, microbial stoichiometry, and their correlation with soil nutrients. Results reveal that soil properties, microbial biomass, and enzymes are influenced by both tree age and depth. Microbial biomass decreases with depth, peaking in young orchards with the highest MBN:MBP ratio. Initially declining, microbial entropy nitrogen rises with tree age. Redundancy analysis identifies OP as pivotal in explaining extracellular enzyme activity. The enzyme C:N ratio exhibits a negative correlation with the MBN:MBP ratio. Additionally, ratios of ln(NAG) to ln(BG), ln(AKP) to ln(BG), and ln(AKP) to ln(NAG) demonstrate positive correlations. Enzyme activity ratios for C, N, and P transformation deviate from the global ecosystem ratio, indicating nuanced nutrient dynamics. Soil vector angles are influenced by tree age, suggesting limitations on microbial metabolism by carbon and phosphorus. Structural equation modeling unveils that soil depth negatively impacts pH, AKP, and Enzyme N:P, while tree age adversely affects Enzyme N:P. Furthermore, MBN:MBP is directly influenced by AKP and soil depth, indirectly by tree age and pH. This study underscores the significance of microbial stoichiometry in evaluating soil resource ecology relations, offering insights into soil microbe-orchard ecosystem dynamics.

Soil aggregate size distribution mediates microbial responses to prolonged acid deposition in a subtropical forest in south China

Extended exposure to acid rain has vastly limited soil microbial activity with the consequences for soil carbon (C) storage, but less is known about the microbial responses within soil aggregates that to some extent determine soil C stabilization. Here, we investigated the main microbial group compositions and the relevant potential enzyme activities within different soil aggregates sizes (microaggregates (<250 μm), small macroaggregates (250–2000 μm), and microaggregates (>2000 μm)) in a subtropical forest with decade-long simulated acid rain (SAR) treatments. Four SAR treatments were set by irrigating plots with water of different pH values (i.e., 3.0, 3.5, 4.0, and 4.5 as a control). Results showed that the SAR treatment significantly inhibited microbial activities, specifically decreasing both bacterial and fungal abundances, leading to declines in C-degrading potential enzyme activities. Conversely, potential enzyme activities related to phosphorus (P) and nitrogen (N) mineralization as well as the enzyme stoichiometry for P/N ratio significantly increased under the SAR treatment. The SAR treatment showed no significant differences in microbial abundance across the three soil aggregate sizes. However, it had a more pronounced effect on potential enzyme activities in their optimal aggregate sizes, such as hydrolytic enzymes like β-glucosidase in macroaggregates and oxidases like phenol oxidase and peroxidase in microaggregates. Overall, C-degrading potential enzyme activities were more strongly decreased in the microaggregates than in macroaggregates, and the distribution in aggregates was significantly altered, transforming from large to small sizes under the SAR treatment, which together may boost SOC stabilization and accumulation. Additionally, our findings indicate that prolonged acid rain also caused soil nutrient limitation and imbalance, particularly for P, in subtropical forests. This study highlights the importance of soil aggregate size in regulating microbial responses to acid rain, which should be integrated into ecosystem models to predict soil biogeochemical cycles under future climate conditions.

Alpine wetlands degradation leads to soil nutrient imbalances that affect plant growth and microbial diversity

Alpine wetlands degrade rapidly due to climate change and human activities. Studying degradation effects on flora, soil, and microbes, and their mechanisms, can aid wetland management and global carbon dynamic insights. Here, we conducted transect surveys across various levels of degradation in the Qinghai-Tibet Plateau, ranging from non-degraded to severely degraded alpine wetlands. Severe degradation reduced aboveground biomass by 72.5%. As degradation intensified, the abundance of high-quality forage plants, especially Cyperaceae, gradually declined. Degradation resulted in soil nutrient deficiencies and stoichiometric imbalances, which significantly affected plant growth and soil microbial diversity. These changes ultimately led to a decline in carbon sequestration. The diversity of microbial and plant communities’ response to degradation aligned with the “intermediate interference hypothesis.” The altered bacterial community composition, which favors oligotrophic dominance, and its nonlinear response to soil stoichiometry and pH, could explain the maintenance of diversity and species richness of microbial communities under intermediate disturbance.

Plant functional traits modulate the effects of soil acidification on above- and belowground biomass

Abstract. Atmospheric sulfur (S) deposition has been increasingly recognized as a major driver of soil acidification. However, little is known about how soil acidification influences above- and belowground biomass by altering leaf and root traits. We conducted a 3-year S-addition experiment to simulate soil acidification in a meadow. Grass (Leymus chinensis (Trin.) Tzvelev) and sedge (Carex duriuscula C.A.Mey) species were chosen to evaluate the linkage between plant traits and biomass. Sulfur addition led to soil acidification and nutrient imbalances. Soil acidification decreased specific leaf area (SLA) but increased leaf dry-matter content (LDMC) in L. chinensis, showing a conservative strategy and thus suppressing aboveground instead of belowground biomass. However, in C. duriuscula, soil acidification increased plant height and root nutrients (N, P, S, and Mn), favoring competition for natural resources through enhanced above- and belowground biomass, i.e., adoption of an acquisitive strategy. Increased soil acidity resulted in an overall reduction in aboveground community biomass by 3 %–33 %, but it led to an increase in community root biomass by 11 %–22 % due to upregulation as a result of higher soil nutrient availability. Our results demonstrate that both above- and belowground plant biomass is affected by S-induced acidification. Understanding the linkage between plant biomass and functional traits contributes to a better understanding of plant–soil feedback in grassland ecosystems.

Contribution of Livestock Farming to Environmental Pollution in China

Purpose: The aim of the study was to examine contribution of livestock farming to environmental pollution in China. Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: The study found that livestock farming in China significantly contributes to environmental pollution, posing substantial challenges to water, air, and soil quality. Intensive livestock operations, characterized by concentrated animal feeding operations (CAFOs), generate large quantities of animal waste containing nutrients and pathogens that contaminate water bodies. Additionally, livestock farming contributes to air pollution through emissions of ammonia and other pollutants, particularly in areas with intensive farming practices. Soil degradation and nutrient imbalance further exacerbate environmental degradation, with higher livestock densities associated with increased soil compaction and nutrient runoff. Unique Contribution to Theory, Practice and Policy: Tragedy of the Commons &amp; Ecological Modernization Theory may be used to anchor future studies on contribution of livestock farming to environmental pollution in China. Promote the adoption of sustainable livestock management practices through capacity building, training, and extension services for farmers. Encourage the implementation of integrated farming systems that optimize resource use, minimize waste generation, and enhance environmental resilience. Strengthen regulatory frameworks and enforcement mechanisms to ensure compliance with environmental standards and promote responsible livestock production. Implement stringent measures to control water pollution from livestock waste, including mandatory wastewater treatment and monitoring programs.

Enhancing soil properties through sustainable agronomic practices reduced the occurrence of kiwifruit vine decline syndrome

AbstractKiwifruit vine decline syndrome (KVDS) is an emerging challenge related to various factors, including water stagnation, soil compaction, root hypoxia, imbalanced soil redox potential, soil nutrient imbalance and fungal pathogens, yet its definitive causes remain unconfirmed. This study compared soils and roots of healthy plants (CTRL group) and plants affected by KVDS (KVDS group) at a kiwifruit orchard (Actinidia chinensis cv. ‘Zesy002’) in Sermoneta (Lazio region), Italy. Our findings indicate that soil redox potential, a parameter related to soil oxidation, and soil macroporosity were significantly lower in the KVDS soils. The water table was also found to be higher in the KVDS block of the orchard, demonstrating a higher soil water content. This suggests less aeration and more water content in KVDS‐affected soils compared to the control. Root analyses showed that KVDS led to browning and decomposition of rhizodermis, decay of the central stele, detachment of the cortex, reduced cell size and the presence of starch granules in the parenchyma, with significant variations in root morphometric parameters. To mitigate KVDS, sustainable agronomic practices, including precision irrigation, green manure, compost addition and water drainage root pruning, were carried out on some KVDS‐symptomatic vines (SUST group). Molecular analyses revealed the presence of 10 fungal species from treated root plants, with Paraphaeosphaeria michotii, Fusarium oxysporum and Ilyonectria vredenhoekensis being frequently isolated from symptomatic KVDS‐affected plants but less from SUST plants. Also, Beauveria bassiana and Bacillus amyloliquefaciens, showed an effect against I. vredenhoekensis and P. michotii, and may be suitable candidates as biocontrol agents. The adoption of sustainable agronomic practices resulted in significantly more healthy plants (46% increase) by the end of the trial, demonstrating that a sustainable soil use and water management at kiwifruit orchards can mitigate KVDS through restoration of natural growth conditions.

Response of rhizosphere soil physicochemical properties and microbial community structure to continuous cultivation of tobacco

PurposeThe health of rhizosphere soil microorganisms is an important indicator to evaluate soil quality. Therefore, understanding the response of rhizosphere soil microorganisms to tobacco crop succession is crucial for promoting the sustainable development of agriculture.MethodsThe microbial diversity and community structure of rhizosphere soil in continuous cropping and non-cropped tobacco for 7 years were analyzed by the Illumina platform.Result(1) Continuous cropping tobacco cause rhizosphere soil acidification and reduction in alkaline nitrogen (AN) and soil organic matter (SOM). (2) Continuous cropping tobacco reduces the diversity of rhizosphere soil microbial communities, increasing harmful functional microorganisms and declining beneficial ones. (3) The abundance of bacteria that perform nitrification and saprophytic fungi in the rhizosphere soil of continuous cropping areas decreases, inhibiting carbon and nitrogen cycling processes. (4) The composition and diversity of the soil rhizosphere microbial community are affected by the imbalance in the physicochemical property of the rhizosphere.ConclusionContinuous cropping tobacco cause rhizosphere soil acidification and nutrient imbalance, and the carbon and nitrogen cycles involved in microorganisms were damaged. Furthermore, the decreased diversity of rhizosphere soil microorganisms and the increased abundance of pathogenic fungi contribute to the continuous cropping obstacles of tobacco.

氮磷添加下典型温带、亚热带森林土壤氮循环功能基因丰度和微生物群落属性数据集

Nitrogen (N) and phosphorus (P) are essential nutrients for soil microbial growth and activities. There are notable differences in the concentrations of N and P and the characteristics of microbial communities observed between temperate and subtropical forests soils, and this is also true for soil vertical profiles. As a consequence of the rise in global atmospheric N deposition, soil nutrient imbalances and P limitation are increasingly aggravated in eastern China. However, there is a lack of systematic dataset showing how N deposition and P addition affect soil N cycling microbes and soil physicochemical properties in eastern China; hence a comprehensive dataset is needed to a better understanding of the impact of N deposition and P addition on soil nitrogen cycle. This dataset is constructed based on the field experimental setup in the forests of Chinese Ecosystem Research Network (CERN). To obtain a systematic dataset on N-cycling microbial communities, we conducted measurements and collected data of soil N-cycling functional genes abundance, N-cycling microbial community diversities and compositions and enzyme activities in three typical forests with N and/or P additions. We collected 0-10 cm top soils from a temperate forest (Changbai Mountain) and two subtropical forests (Qianyanzhou and Dinghu Mountain) with field N and/or P additions, and the soils along 0-80 cm vertical profiles without nutrient additions. The N-cycling functional genes involved in the datasets cover ammonia oxidizing archaea amoA, ammonia oxidizing bacteria amoA, nirK, nirS, nosZ, qnorB, narG, nir, nifH and chiA. The potential activities included in the datasets cover nitrification activity, denitrification activity, nitrogen fixation activity and organic nitrogen decomposition enzyme activity. The datasets also include soil physiochemical properties, including soil pH, moisture content, N2O emission, net nitrification rate and the concentrations of organic carbon, NH4+ , NO3− , available phosphorus, total nitrogen, total carbon, total phosphorus and dissolved organic carbon. The creation and sharing of the datasets can provide data and support for understanding the microbial mechanisms of soil N-cycling and the modelling processes under the scenario of aggravated N deposition and P addition. The datasets will also provide support for forest management efforts with regard to greenhouse gas N2O emission, N and nutrient loss in forest ecosystems.

Soil Enzyme Activity Differs among Native Species and Continuously Planted Eucalyptus Plantations

In recent years, monoculture and multi-rotation successional Eucalyptus plantations have given rise to several environmental issues, including the degradation of soil quality and nutrient imbalance, and the conversion of logging sites to multi-rotation Eucalyptus plantations has attracted considerable attention from the scientists involved. However, the effects of different management strategies on soil extracellular enzyme activities (EEAs) and enzyme stoichiometry (ES) in degraded Eucalyptus plantations are not clear. In this study, we investigated the responses and mechanisms of soil physicochemical properties, microbial biomass, carbon, and nitrogen- and phosphorus-acquiring enzyme activities, as well as the microbial resource requirements of Eucalyptus plantations, under different management strategies. The findings revealed that second-rotation (TWE) and third-rotation (THE) continuous plantings of pure Eucalyptus plantations resulted in significant decreases in soil organic carbon (SOC), total nitrogen (TN) and effective available phosphorus (AP) contents, while soil nutrient contents increased after the introduction of Manglietia glauca to form mixed forests (EM) with Eucalyptus or pure Manglietia glauca (M). Meanwhile, phosphorus-acquiring enzymes significantly increased with successive rotations of Eucalyptus (TWE and THE), while EEAC:P and EEAN:P gradually decreased and phosphorus limitation gradually increased compared to that of a native-species-mixed plantation (CK). After the introduction of Manglietia glauca (EM and M), phosphorus-acquiring enzyme activities showed lower levels and there were significant increases in EEAC:P and EEAN:P compared to those of continuous plantings of pure Eucalyptus plantations, which reduced microbial phosphorus demand. Moreover, soil nutrients played a more significant role in altering the EEAs and ES than did microbial biomass (0–10 cm: 72.7% &gt; 53.3%, 10–20 cm: 54.5% &gt; 32.6%). The results showed that EM and M improved soil fertility quality conditions and alleviated soil nutrient phosphorus limitations for soil microorganisms. Therefore, the introduction of Manglietia glauca, either to form mixed forests with Eucalyptus or in rotation with Eucalyptus, can be used as technical means for the conversion of multi-rotation successive Eucalyptus plantations.

Impact of Crop Residue and Green Manure Management in Rice Crop on Soil Nutrient Dynamics in Tarai Belt of Shivalik Himalaya, India

The study explores the effects of different soil management practices on various soil properties within the Tarai Belt of the Shivalik Himalaya region to assess the effects of different nutrient management strategies on various soil properties in the context of rice cultivation. Ten treatments were employed, T1 (100% recommended dose of NPK fertilizers), T2 (50% crop residue + 50% recommended NPK dose), T3 (50% crop residue + 50% recommended NPK dose with the addition of Pusa decomposer), T4 (50% crop residue + 50% Green Manure (GM), T5 (50% crop residue + 50% GM with Pusa decomposer), T6 (Crop residue at 2.5 tons per hectare + Pusa decomposer), T7 (Crop residue at 2.5 tons per hectare without Pusa decomposer), T8 (Absolute control group with no fertilizer application), T9 (150% recommended NPK dose), and T10 (100% recommended NPK dose with the addition of Farm Yard Manure at a rate of 5 tons per hectare, along with Zinc and Boron supplementation). including varying combinations of crop residues, organic and inorganic fertilizers, and green manure. Soil properties examined included soil organic carbon, available nitrogen, available phosphorus, available potassium, pH, and electrical conductivity (EC) at two different soil depths (0-15 cm and 15-30 cm. Organic sources enhanced soil organic carbon, while inorganic sources notably improved the availability of nitrogen, phosphorus, and potassium. The results showed that treatments incorporating both organic and inorganic nutrient sources demonstrated improved soil health and nutrient availability, with treatment T9 (150% recommended dose of fertilizer, RDF) showing the best results, particularly in terms of available nitrogen, phosphorus, and potassium. However, the sustainability of this approach over the long term may be a concern. Treatment T10, which combined 100% RDF with farmyard manure, zinc, and boron supplementation, emerged as a promising alternative for sustainable soil management. Treatment T3, with the incorporation of crop residues and the application of Pusa decomposer, also showed potential for maintaining soil health. These findings emphasize the importance of a balanced approach to nutrient management that combines readily available nutrients from inorganic sources with the long-term benefits of organic matter.&#x0D; In summary, this study emphasizes the importance of integrated nutrient management and sustainable agricultural practices for enhancing soil fertility and overall soil health, thereby contributing to sustainable crop production. These findings hold significance for addressing soil nutrient imbalances and ensuring the well-being of farmers and environmental sustainability.

Microbial Exudates as Biostimulants: Role in Plant Growth Promotion and Stress Mitigation.

Microbes hold immense potential, based on the fact that they are widely acknowledged for their role in mitigating the detrimental impacts of chemical fertilizers and pesticides, which were extensively employed during the Green Revolution era. The consequence of this extensive use has been the degradation of agricultural land, soil health and fertility deterioration, and a decline in crop quality. Despite the existence of environmentally friendly and sustainable alternatives, microbial bioinoculants encounter numerous challenges in real-world agricultural settings. These challenges include harsh environmental conditions like unfavorable soil pH, temperature extremes, and nutrient imbalances, as well as stiff competition with native microbial species and host plant specificity. Moreover, obstacles spanning from large-scale production to commercialization persist. Therefore, substantial efforts are underway to identify superior solutions that can foster a sustainable and eco-conscious agricultural system. In this context, attention has shifted towards the utilization of cell-free microbial exudates as opposed to traditional microbial inoculants. Microbial exudates refer to the diverse array of cellular metabolites secreted by microbial cells. These metabolites enclose a wide range of chemical compounds, including sugars, organic acids, amino acids, peptides, siderophores, volatiles, and more. The composition and function of these compounds in exudates can vary considerably, depending on the specific microbial strains and prevailing environmental conditions. Remarkably, they possess the capability to modulate and influence various plant physiological processes, thereby inducing tolerance to both biotic and abiotic stresses. Furthermore, these exudates facilitate plant growth and aid in the remediation of environmental pollutants such as chemicals and heavy metals in agroecosystems. Much like live microbes, when applied, these exudates actively participate in the phyllosphere and rhizosphere, engaging in continuous interactions with plants and plant-associated microbes. Consequently, they play a pivotal role in reshaping the microbiome. The biostimulant properties exhibited by these exudates position them as promising biological components for fostering cleaner and more sustainable agricultural systems.

Impact of Biofertilizers &amp; Different doses of NPK on Growth and Photosynthetic Pigments of Okra Plant (Abelmoschus Esculentus L. Moench)

Okra is an herbaceous hairy annual plant that belongs to the family Malvaceae. It is cultivated in tropical, subtropical, and warm temperate regions around the world. The present work was carried out to study the effect of biofertilizers (Azotobacter + Bacillus) and different concentrations of Nitrogen, Phosphorus, and Potassium i.e.NPK on growth and photosynthetic pigments of okra (Abelmoschus esculentus L. Moench). Okra can be named a multipurpose crop as its various parts such as leaves, buds, flowers, pods, stems and seeds can be used for different purposes [1]. Okra is rich in dietary fiber, vitamins, oils, etc. Application of hazardous fertilizers causes a nutrient imbalance in soil, With respect to reducing the causes due to chemical fertilizers, biofertilizers are suited best to maintain higher productivity and yield of crops. Random block design (RBD) was selected as an experimental design. The treatments combination taken are T0- Control, T1- Azotobacter + 50% NPK, T2- Azotobacter (2.5 kg/ha) + 100% NPK, T3- Bacillus (2.5 kg/ha) + 50% NPK, T4- Bacillus (2.5 kg/ha) + 100% NPK, and T5 with NPK 100%. The final result revealed, that the treatment combination with Azotobacter + 100% NPK (T2) showed the highest value of plant height (65.60 cm), number of leaves per plant(62.36), number of flowers per plant (27.40), and also carotenoid content (2.82 mg/g), chlorophyll a(2.47 mg/g) and chlorophyll b(3.25 mg/g) were observed maximum. So, it can be concluded through this paper that the combination of Azotobacter 2.5 kg/ha + 100% NPK (T2) is suitable for the okra plant for better growth and enhancement of photosynthetic potential in-field practices.

Characteristics and utilization of black soils in Indonesia

Black soils store a high amount of soil organic carbon (SOC) and play a crucial role in climate change, food security, and land degradation neutrality. However, data and information regarding black soils in tropical regions, including Indonesia, are limited. This study aimed to characterize and identify the utilization of black soils in Indonesia based on legacy soil survey data. We collated 142 soil pedon samples of Mollisols from articles, technical reports, and existing datasets. The site information (site position, elevation, land use type, parent material) and selected physicochemical properties were stored in a spreadsheet, from which exploratory data analysis was conducted. The result showed that the median SOC content was 1.53%, ranging from 0.6 to 8.2 %; cation exchange capacity was 30 cmol kg&lt;sup&gt;-1&lt;/sup&gt;, ranging from 9 to 95 cmol kg&lt;sup&gt;-1&lt;/sup&gt;; base saturation was 87%, ranging from 11 to 100 %; and bulk density was 1.21 g cm&lt;sup&gt;-3&lt;/sup&gt;, ranging from 1.13 to 1.36 g cm&lt;sup&gt;-3&lt;/sup&gt;. Other soil characteristics (particle size distribution, exchangeable bases, pH, pore, and water retention) varied with horizon type and land use/land cover. The black soils have been used for paddy fields, dryland farming, and gardens with low management intensity. Main cultivated crops include rice (&lt;em&gt;Oryza sativa&lt;/em&gt;), corn (&lt;em&gt;Zea mays&lt;/em&gt;), cassava (&lt;em&gt;Manihot esculenta&lt;/em&gt;), sweet potato (&lt;em&gt;Ipomoea batatas&lt;/em&gt;), and nutmeg (&lt;em&gt;Myristica fragrans&lt;/em&gt;), clove (&lt;em&gt;Syzygium aromaticum&lt;/em&gt;), coconut (&lt;em&gt;Cocos nucifera&lt;/em&gt;), and cocoa (&lt;em&gt;Theobroma cocoa)&lt;/em&gt;. Threats to black soil functions include soil erosion, carbon loss, and nutrient imbalance. Soil and water conservation measures, integrated soil nutrient management, and agroforestry are among the best land management practices for black soils.

Nanofertilizer Use for Adaptation and Mitigation of the Agriculture/Climate Change Dichotomy Effects

Agriculture is considered a significant climate change (CC) driver due to greenhouse gas (GHG) emissions and the loss of fertilizers that contribute to water eutrophication. On the other hand, climate change effects are already impacting agriculture, endangering food security. This paper explores the dichotomies of the effects of agriculture on CC as well as of CC on agriculture, focusing on the contribution that nanofertilizers can bring to this complex system in both directions. The strategies to reduce CC while adapting and mitigating its effects must be a global effort. It is not possible to focus only on the reduction in GHG emissions to stop the effects that are already being felt worldwide. Nanofertilizers, especially slow- and controlled-release nanofertilizers, can reduce the nutrient input and also boost productivity while mitigating some CC effects, such as soil nutrient imbalance and agricultural emissions. As so, this review highlights the benefits of nanofertilizers and their role as a part of the strategy to reduce the reach of CC and mitigate its ever-growing effects, and presents some guidelines for the increased use of these materials in order to enhance their efficacy in this strategy.

Biofertilizer based on halotolerant microorganisms promotes the growth of rice plants and alleviates the effects of saline stress.

Long-term soil salinization easily contributes to soil hardness, soil nutrient imbalance, and soil microbial diversity reduction, resulting in low rice yields in the salinized fields, and microbial remediation is one of the important measures to improve salinized soil. To verify the effect of biofertilizer based on halotolerant microorganisms on promoting rice growth and alleviating saline stress, this study discussed the effects of biofertilizer on soil microbial diversity and community structure and analyzed the correlation between the formation of microbial community structure and soil nutrient factors in the salinized field. The result, in comparison with applying inorganic fertilizer (referred to as CK), showed that notably increased soil available nitrogen, available phosphorus, available potassium, and rice paddy yield (p < 0.05) and significantly decreased soil electrical conductivity (p < 0.05) were achieved via biofertilizer (referred to as G2). Additionally, the application of biofertilizer contributes to the increase in soil microbial diversity and reorganization of microbial community structure, and through the analysis of linear discriminant analysis effect size, a notable difference in relative abundance was found in 13 genera, 6 families, and 3 orders between the control group and experimental groups (p < 0.05), and by linear discriminant analysis, Desulfomonas was further identified as the differentiated indicator. The redundancy analysis showed that available phosphorus and cation exchange capacity were the key environmental factors that affected microbial community structure and composition. Through bacterial functional prediction, increased rhizosphere soil bacterial metabolism, enzyme activity, membrane transport, and other potential functions were achieved by applying biofertilizer. Therefore, the application of biofertilizer could significantly alleviate rice growth stress and increase nutrient supply capacity in saline soil. These findings provide theoretical support for soil microbial improvement technology in the salinized field.

Functional group dominance-mediated N:P effects on community productivity depend on soil nutrient levels

Plant functional groups can mediate impacts of soil nutrient imbalances (i.e., a condition where an essential nutrient element is relatively deficient or excessive) on community productivity via the complementary roles of individual species. However, it is still unclear whether the relative dominance of plant functional groups can alter the effects of available N:P ratios on community productivity and whether such an effect depends on the total amount of nutrients available in the soil. We created experimental plant communities with six grassland species of three functional groups (two species of grasses, legumes, and non-leguminous forbs) in four types (grass-dominant, forb-dominant, legume-dominant, and even community) under three available N:P ratios (1.7, 15, and 135, i.e., low, intermediate, and high) and two nutrient levels (the total amount of nutrients was low and high). In the even, the grass-dominant, and the forb-dominant community, community biomass was significantly higher at the low than at the high N:P ratio, but it did not differ significantly among the three N:P ratios at the low-nutrient level. By contrast, in the legume-dominant community, although community biomass was also significantly higher at the low than at the high N:P ratio, it was significantly lower at the low N:P ratio than at the high N:P ratio at the low-nutrient level. Biomass of functional groups (grasses, legumes, and forbs) showed the similar pattern as community biomass, except in the legume-dominant community at the high-nutrient level, which did not differ between the three N:P ratios. Our results suggest that the dominance of plant functional groups can mediate the impacts of N:P ratios on the productivity of grassland communities, but such an impact varied depending on the total amount of nutrients available in the soil.

Effect of Different Poultry Manure on the Performance of Tomatoes (Lycopersicon esculentum mill)

Purpose: Tomato is one of the most popular and versatile vegetables in the world and organic production with high yields of desirable quality are a target of many producers. However, the yield of tomatoes in Uganda are low compared to other parts of the world. The reason is that most soils in Uganda are low in fertility. There is widespread soil degradation, due to massive soil erosion resulting into loss of organic matter, high soil acidity and nutrient imbalance hence low crop yields. This study aimed at establishing the effect of different poultry manure on the performance of tomatoes.&#x0D; Methodology: The field trials were conducted in the mid altitude environment at BSU farm. Four treatments which included broiler, Layer, combination of Broiler and Layer chicken manure and the control were applied. The study was carried out in a randomized complete block design replicated four times. Measurements were made on number of leaves, number of flowers, plant height, fruit weight, fruit size, number of tomatoes and yield per hectare. Broiler and layer chicken manure increased the number of leaves, plant height number of flowers, number of fruits, fruit weight and fruit size significantly.&#x0D; Findings: The results indicate that poultry manure is very rich in macro nutrients. Among the treatments, broiler and layer chicken manure gave the highest fruit yield of 13.8 and 13.4 tons per hectare (t/ha) respectively. A combination of the manure produced 12.8 t/ha and the control treatment gave the lowest yield of 8.1 tons per hectare (t/ha). There was no significant difference between broiler and layer chicken manure. Both manures were equally good and enhanced yield. Therefore, farmers may opt for either of the two depending on the availability.&#x0D; Recommendation: The study recommend that either broiler or layer chicken manure can be used for production of tomato in order to achieve high yields.

Environmental Risk from Organic Residues

Soil nutrient imbalance is a global threat to food security and ecosystem sustainability but adding organic residues or constructing anthropogenic soils and technosols can optimize it. However, FAO considers organic residues not “risk-free”, mainly due to their heavy metal content. Despite the fact that applying pruning residues to soil is a worldwide fertilization practice, its potential heavy metal risk has been poorly studied. This work characterizes Cu, Zn, Cd, Cr, Ni and Pb elemental composition concentration and their solubility content in almond tree pruning, commercial peat substrate, hay straw, olive tree pruning, pomegranate peel, pine needle, date palm leaf pruning, sewage sludge compost and vine pruning. Furthermore, we compare the legal frameworks governing heavy metal content in agricultural substrates to heavy metal concentration in each residue. Results show that commercial peat substrate is the only one among those studied that surpasses the threshold value for Cr in agricultural substrates. All pruning residues met the heavy metal threshold value; hence, their application to soil involves minimal soil toxicity. Moreover, the solubility index of heavy metals and the maximum quantity of each residue are crucial to discerning a heavy metal-free organic fertilization plan.

Indian fertilizer subsidy conundrum: Tracking the recent developments

Subsidies to fertilizers have played a crucial role in yield improvement in Indian agriculture, yet it is being criticised recently for issues like soil nutrient imbalance, inequity in distribution etc. Several policies are being implemented in India to control scorching fiscal burden due to fertilizer subsidy, control the diversion of subsidised fertilizers and better the soil nutrient balance. Present study was carried out at the Division of Agricultural Economics, ICAR- IARI, New Delhi during 2020–21 to understand the status of fertilizer subsidies in India and its distribution. The prime objective of the study is to assess who benefits from the fertilizer subisides. Secondary data collected from various issues of Fertilizer Statistics, Agricultural Statistics at a Glance, and the Direct Benefit Transfer (DBT) dashboard, as well as on primary data collected from 200 farmers and 60 fertilizer retailsers of Karnal district, Haryana are used for analysis. The farmers, for whom the subsidies are announced, don't seem to get a fair share of it. It is the industry that benefits most from the subsidies, and they have been heavily subsidised especially in the 1990s and after 2010. The stakeholder perception of DBT is in support of the scheme, and both farmers as well as retailers reported increased fertilizer availability after the implementation of the scheme. Aadhar authenticated fertilizer purchase under DBT is hence a welcome development that has the potential to manage the irregularities surrounding the fertilizers to some extent.