Improve Soil Quality Research Articles

Willingness to Pay for Agricultural Soil Quality Protection and Improvement

Understanding and estimating the economic value that society places on agricultural soil quality protection and improvement can guide the development of policies aimed at mitigating pollution, promoting conservation, or incentivizing sustainable land management practices. We estimate the general public’s willingness to pay (WTP) for agricultural soil quality protection and improvement in Spain (n = 1000) and the UK (n = 984) using data from a cross-sectional survey via Qualtrics panels in March–April 2021. We use a double-bound dichotomous choice contingent valuation approach to elicit the individuals’ WTP. We investigate the effect of uncertainty on the success of policies aiming at achieving soil protection. In addition, to understand the heterogeneity in individuals’ WTP for agricultural soil quality protection and improvement, we model individuals’ WTP through individuals’ awareness and attitudes toward agricultural soil quality protection and the environment; trust in institutions; risk and time preferences; pro-social behavior; and socio-demographics in Spain and the UK. We found that there is significant public support for agricultural soil quality protection and improvement in Spain and the UK. We also found that the support does not vary significantly under uncertainty of success of policies aiming at achieving soil protection. However, the individual’s reasons for supporting agricultural soil quality protection and improvement are found to depend on the level of uncertainty and country. Hence, promoting public support for soil protection needs to be tailored according to the level of the general public’s perceived uncertainty and geographic location.

Anthropogenic restoration exhibits more complex and stable microbial co-occurrence patterns than natural restoration in rubber plantations

Forest restoration is an effective method for restoring degraded soil ecosystems (e.g., converting primary tropical forests into rubber monoculture plantations; RM). The effects of forest restoration on microbial community diversity and composition have been extensively studied. However, how rubber plantation-based forest restoration reshapes soil microbial communities, networks, and inner assembly mechanisms remains unclear. Here, we explored the effects of jungle rubber mixed (JRM; secondary succession and natural restoration of RM) plantation and introduction of rainforest species (AR; anthropogenic restoration established by mimicking the understory and overstory tree species of native rainforests) to RM stands on soil physico-chemical properties and microbial communities. We found that converting tropical rainforest (RF) to RM decreased soil fertility and simplified microbial composition and co-occurrence patterns, whereas the conversion of RM to JRM and AR exhibited opposite results. These changes were significantly correlated with pH, soil moisture content (SMC), and soil nutrients, suggesting that vegetation restoration can provide a favorable soil microenvironment that promotes the development of soil microorganisms. The complexity and stability of the bacterial-fungal cross-kingdom, bacterial, and fungal networks increased with JRM and AR. Bacterial community assembly was primarily governed by stochastic (78.79 %) and deterministic (59.09 %) processes in JRM and AR, respectively, whereas stochastic processes (limited dispersion) predominantly shaped fungal assembly across all forest stands. AR has more significant benefits than JRM, such as a relatively slower and natural vegetation succession with more nutritive soil conditions, microbial diversity, and complex and stable microbial networks. These results highlight the importance of sustainable forest management to restore soil biodiversity and ecosystem functions after extensive soil degradation and suggest that anthropogenic restoration can more effectively improve soil quality and microbial communities than natural restoration in degraded rubber plantations.

Productivity and health of soil cultivated with forage cactus (Opuntia cochenillifera (L.) Mill.) with combined use of topsoil and biochar

Agricultural production in semi-arid environments represents a significant challenge, as these are areas that have soils with limited nutrient availability and scarcity of precipitation, which require adaptive and innovative strategies. The application of biochar to improve soil quality and increase productivity has been well studied. However, there is still a gap regarding the use of biochar with the technique of incorporating different topsoils on plant development and soil health. This technique has emerged as an alternative for producers to increase soil fertility. This technique is emerging as an alternative for producers to enhance soil fertility. The hypothesis of the present study is that the use of biochar associated with the topsoil technique increases the productivity and yield of cactus, mainly by changing the properties of the soil and its microbiological interactions. To test this hypothesis, we used different sources of biochar (bean husk, coffee grounds and soursop residue) in association with two types of topsoil (Acrisol and Luvisol). Our analyzes revealed changes on plants development, chemical and microbiological soil attributes. The topsoil technique significantly interfered with mean cladode length (COM), stem diameter (DI), plant height (AL), pH, Na+, K+ and urease enzymatic activity, while biochar had a significant effect on microbial respiration rate. In general, our results expand the knowledge about the use of biochar associated with topsoil, suggesting it as a promising, low-cost way that guarantees the conservation and health of the agroecosystem, contributing with important information for the development of alternative technologies to conventional ones.

Effects of humic acid application on bacterial diversity under maize cultivation

AbstractThe fundamental ecosystem processes in soil are regulated by microbial communities, and community diversity is implicated by soil environmental conditions. Humic acid (HA) improves soil quality and fertility, stimulating the microbial environment, but the detailed effects remain poorly understood. We investigated the effects of HA rates on soil bacterial diversity, particularly on species richness and community composition in the rhizosphere of corn (Zea mays). Inorganic fertilizer (T2), HA 0.5% (T3), HA 1.0% (T4), HA 1.5% (T5), and HA 2.0% (T6) were applied in soil. Initial soil (O1) and control after harvesting (T1) were included. A total of 3601 operational taxonomic units were captured from the overall sample, and analysis of 16S ribosomal ribonucleic acid amplicon sequencing data indicated that HA did not notably impact species richness. Intriguingly, HA induced changes in bacterial community composition, along with the relative prevalence of specific taxa. Certain associations between soil chemical properties and abundance distribution have been uncovered. Notably, exchangeable Mg2+, Ca2+, and available phosphorus were strongly related to the relative abundance of bacterial phyla. Furthermore, HA potentially shaped the specific bacterial taxa, as the application of HA at different rates had distinct effects on the member of bacterial abundance of each taxon. These findings enhance our understanding of communities potentially being increased or shifted by HA rate addition in short‐term corn cultivation.

Managing Residue Return Increases Soil Organic Carbon, Total Nitrogen in the Soil Aggregate, and the Grain Yield of Winter Wheat

Soil tillage and maize residues return are important practices for tackling and promoting soil quality and improving crop yield in the North China Plain (NCP), where winter wheat production is threatened by soil deterioration. Although maize residues incorporation with rotary tillage (RS) or deep plowing tillage (DS) is widespread in this region, only few studies have focused on rotation tillage. Four practices, namely RT (continuous rotary tillage without maize residues return), RS, DS, and RS/DS (rotary tillage every year and deep plowing interval of 2 years), were evaluated under field conditions lasting a period of 5 years. After a 5-year field experiment, the mean soil bulk density of the 0–30 cm soil layer decreased significantly with RS, DS, and RS/DS, i.e., by 4.19%, 6.33%, and 6.71% compared with RT, respectively. The treatments greatly improved the total soil porosity, soil aggregate size distribution, soil aggregate stability, and the root length density in the 0–30 cm soil layers. Residues return with DS and RS/DS treatments significantly increased the soil organic carbon (SOC) and total nitrogen (TN) storage in the 0–30 cm soil layer, mainly owed to the increases in the SOC and TN pool associated with the macro-aggregate. A positive trend in the grain yield was noted under both DS and RS/DS conditions, whereas a decreasing tendency was presented in continuous rotary treatments. In summary, RS/DS treatment significantly increased the amount of SOC and TN, improved the particle size distribution of soil aggregates, and thus improved the soil’s physicochemical properties, which is beneficial for wheat to achieve high yields. Our results suggested that RS/DS was a highly efficient practice to improve soil quality and increase crop production in the NCP.

Assessing the Alteration of Soil Quality under Long-Term Fertilization Management in Farmland Soil: Integrating a Minimum Data Set and Developing New Biological Indicators

The key role of soil quality improvement in achieving sustainable agricultural development based on highly intensive use of farmland is increasingly being recognized, as is the ponderance of suitable evaluation of the soil quality. The overarching goal of this study was to determine an accurate assessment framework by the comparison of the scoring function (linear and non-linear) and integration method (area and weighted additive), which integrally evaluates the soil quality of an eleven-year field fertilization experiment (including CK, no fertilizer; CF, conventional fertilization; SF, formulated fertilization; SFO, SF with organic fertilizer). Thirty-three properties, including eighteen physiochemical-related and fifteen biological-related properties, associated with soil functions were measured as potential soil quality indicators, and the soil multifunctionality (SMF) was applied to validate the soil quality indices (SQIs). Principal component analysis and relationship analysis were used with indicators sensitive to management to determine a minimum data set (MDS). The results showed that the electrical conductivity, large macroaggregate-associated total nitrogen, small macroaggregate-associated organic carbon, carbon fixation, and enzyme activities of phenol oxidase and cellulase were chosen as the MDS. All the SQIs were significantly correlated with the SMF (p < 0.05). The fertilization strategies affected most indicators in different ways, and the index developed using the non-linear function and weighted additive integration method (SQI-NL) had the best sensibility and discriminability. The SQI value with the SQI-NL-MDS method was higher following the fertilization treatments than that of no fertilizer (p < 0.05), and the treatment of the organic fertilizer had the highest SQI value (0.66). Soil quality evaluation in long-term fertilized farmland suggested that the soil quality constraints between treatments of synthetic and organic fertilizer are related to the soil functions of nutrient cycling and sustain biological activity due to their higher contribution rates to the SQI in the organic fertilizer treatment, which provides insights into ways to reduce the gap in soil quality. The framework method can provide an accurate quantitative tool for the evaluation of soil quality from the target indicators by bridging management objectives and field-level actions.

Exploring the Organic Acid Secretion Pathway and Potassium Solubilization Ability of Pantoea vagans ZHS-1 for Enhanced Rice Growth.

Soil potassium deficiency is a common issue limiting agricultural productivity. Potassium-solubilizing bacteria (KSB) show significant potential in mitigating soil potassium deficiency, improving soil quality, and enhancing plant growth. However, different KSB strains exhibit diverse solubilization mechanisms, environmental adaptability, and growth-promoting abilities. In this study, we isolated a multifunctional KSB strain ZHS-1, which also has phosphate-solubilizing and IAA-producing capabilities. 16S rDNA sequencing identified it as Pantoea vagans. Scanning electron microscopy (SEM) showed that strain ZHS-1 severely corroded the smooth, compact surface of potassium feldspar into a rough and loose state. The potassium solubilization reached 20.3 mg/L under conditions where maltose was the carbon source, sodium nitrate was the nitrogen source, and the pH was 7. Organic acid metabolism profiling revealed that strain ZHS-1 primarily utilized the EMP-TCA cycle, supplemented by pathways involving pantothenic acid, glyoxylic acid, and dicarboxylic acids, to produce large amounts of organic acids and energy. This solubilization was achieved through direct solubilization mechanisms. The strain also secreted IAA through a tryptophan-dependent metabolic pathway. When strain ZHS-1 was inoculated into the rhizosphere of rice, it demonstrated significant growth-promoting effects. The rice plants exhibited improved growth and root development, with increased accumulation of potassium and phosphorus. The levels of available phosphorus and potassium in the rhizosphere soil also increased significantly. Additionally, we observed a decrease in the relative abundance of Actinobacteria and Proteobacteria in the rice rhizosphere soil, while the relative abundance of genera associated with acid production and potassium solubilization, such as Gemmatimonadota, Acidobacteria, and Chloroflexi, as well as Cyanobacteria, which are beneficial to plant growth, increased. These findings contribute to a deeper understanding of the potassium solubilization mechanisms of strain ZHS-1 and highlight its potential as a plant growth-promoting rhizobacteria.

Greenhouse gas emissions from the growing season are regulated by precipitation events in conservation tillage farmland ecosystems of Northeast China

Reducing greenhouse gas (GHG) emissions from agricultural ecosystems is vital to mitigate global warming. Conservation tillage is widely used in farmland management to improve soil quality; however, its effects on soil GHG emissions remain poorly understood, particularly in high-yield areas. Therefore, our study aimed to evaluate the effects of no-tillage (NT) combined with four straw-mulching levels (0 %, 33 %, 67 %, and 100 %) on GHG emission risk and the main influencing factors. We conducted in-situ observations of GHG emissions from soils under different management practices during the maize-growing season in Northeastern China. The results showed that NT0 (705.94 g m−2) reduced CO2 emissions by 18 % compared to ridge tillage (RT, 837.04 g m−2). Different straw mulching levels stimulated N2O emissions after rainfall, particularly under NT combined with 100 % straw mulching (2.89 kg ha−1), which was 45 % higher than that in any other treatments. The CH4 emissions flux among different treatments was nearly zero. Overall, straw mulching levels had no significant effect on the GHG emissions. During the growing season, soil NH4+-N (< 20 mg kg−1) remained low and decreased with the extension of growth stage, whereas soil NO3−-N initially increased and then decreased. More importantly, the results of structural equation modeling indicate that: a) organic material input and soil moisture are key factors affecting CO2 emissions, b) nitrogen fertilizer and soil moisture promote N2O emissions, and c) climatic factors exert an inexorable influence on the GHG emissions process. Our conclusions emphasize the necessity of incorporating precipitation-response measures into farmland management to reduce the risk of GHG emissions.

Improving the value of planting and breeding waste compost in agricultural applications: A zucchini cultivation case and circular agricultural models analysis

An important way of utilizing agricultural wastes to improve soil quality is the use of planting and breeding waste compost (PBWC). However, the impact of compost on agricultural production systems is unclear. Therefore, in order to study the effect of PBWC on crop growth, soil environment, and circular agriculture, PBWC [sheep manure (SM): tail vegetable (TV): corn straw (CS) = 6: 3: 1] was used based on chemical fertilizer reduction for zucchini production. In zucchini production systems, R9 (chemical fertilizer reduction by 30 % + 9,000 kg ha−1 PBWC) treatment was most effective in improving the quality and yield of zucchini fruits, mainly by improving the soil microenvironment, manifested in (1) increasing soil alkali-hydrolyzable nitrogen (AN) available potassium(AK), and soil organic matter (SOM), reducing EC, and improving C/N. (2) Increasing the richness and metabolic capacity of bacterial community. (3) Increasing the abundance of Proteobacteria, a phylum with absolute dominance (up to 32.46 %). Then, an optimization model of “summer corn − greenhouse zucchini − fattened sheep” was constructed to analyze the effect of changes in fertilizer dosage usage on the whole model. Compared with the local traditional recycling model, the optimized system reduced the ratio of inorganic to organic nitrogen input from 2.8:1 to 1.4:1, increased the recycling rate of nitrogen (N), phosphorus (P), and potassium (K) by 31.28 %, 50.84 %, and 30.25 %, respectively, and the net energy yield ratio (EYR) increased by 1.04. The optimized recycling system had significant economic and environmental benefits, which would become the basis for moving towards more sustainable farming. Overall, the circular agriculture model with PBWC returning as the core achieves sustainable production by improving material recycling and soil microenvironment. Therefore, chemical fertilizer reduction by 30 % combined with 9000 kg ha−1 PBWC can be used in practical production to improve the productivity of the circular agriculture model and achieve high yield and high quality crops.

Improving crop productivity by optimizing straw returning patterns to delay senescence of wheat leaves

Early senescence in the conventional pattern of wheat production is widespread, leading to decline in potential for increased and stabilized yield. Straw returning could effectively improve soil quality and extend the growth period of wheat. However, the response mechanism of straw returning in delaying leaves senescence and increasing crop productivity by regulating the internal physiological and biochemical processes of leaves is not clear. A field experiment was conducted in northwest China in 2013 (the data used in the text from 2021–2023) with four straw returning patterns: no tillage with straw mulching (NTSM), no tillage with straw standing (NTSS), conventional tillage with straw returning (CTS), and conventional tillage with straw removing (CT, the control). The antioxidant enzyme activities, cellular osmotic contents, endogenous hormones contents, stay-green capability of wheat leaves, photosynthetic source, and crop yield were investigated and analyzed. We found that no tillage with straw mulching (NTSM and NTSS) could effectively enhance the antioxidant and cell osmoregulation capabilities of wheat leaves during the grain filling process. Compared to CT, the SOD activity of NTSM and NTSS increased by 24.9–28.2 % and 18.6–20.4 %, respectively. Soluble protein content increased by 37.3–43.2 % and 25.2–57.1 %, and proline content increased by 37.3–78.4 % and 26.5–31.4 %. However, malondialdehyde content decreased by 20.3–21.4 % and 19.2–23.2 %. It was evident that the NTSM treatment provided a solid physiological foundation for delaying leaves senescence. NTSM could also help to maintain the homeostasis of endogenous hormones in wheat leaves during the grain filling period. Compared to CT, the contents of zeatin, salicylic acid, and jasmonic acid of NTSM increased by 23.3–27.2 %, 18.5–22.0 %, and 15.2–15.3 %, while abscisic acid content of NTSM decreased by 9.4–10.2 %. Based on physiological changes within the leaves, NTSM and NTSS reduced stay-green of leaves before 45 d post-emergence by 20.6–20.9 % and 17.5–17.8 % compared to CT. After 45 d post-emergence, NTSM and NTSS increased stay-green of leaves by 21.9–23.0 % and 17.0–19.1 % over CT. Thus, the grain yield of NTSM was 15.0–22.2 % and 9.0–11.3 % higher than that with CT and CTS, primarily due to the synchronous increase in ear number and thousand grain weight. Therefore, no tillage with straw mulching promoted the mobilization of antioxidant and cellular osmoregulatory responses, optimized endogenous hormones signaling, and maintained higher photosynthesis source and stay-green during the grain filling stage, thus delaying leaves senescence and increasing crop productivity in arid irrigated areas.

Selecting appropriate forage cover crops to improve growth, yield, and fruit quality of wolfberry by regulation of photosynthesis and biotic stress resistance

Forage cover crops have the potential to improve soil quality and orchard productivity, but their effects on wolfberry (Lycium barbarum L.) plants are still unclear. In this study, we conducted field and greenhouse experiments between 2019 and 2021, with 10 forage species as cover crops. We observed the growth, yield, fruit quality, and photosynthetic characteristics of wolfberry plants, as well as the occurrence of plant diseases and pests. Based on averaged data for all forage species, cover cropping facilitated plant growth, maintained fruit yield, and promoted leaf photosynthesis in wolfberry compared to monocropping. This was exemplified by a notable increase in the branch number of wolfberry plants under ryegrass treatment, with marginal increase in branch length under evergreen grass (lvyuan 5) and mangold treatments. Cover cropping additionally improved wolfberry quality through increasing carotenoid, flavonoid, and ascorbic acid contents by 21%, 53%, and 127%, respectively (P< 0.05). The presence of mangold, alfalfa, sweet sorghum, ryegrass, and feather grass reduced powdery mildew-induced leaf damage in wolfberry plants by 69% (P< 0.05). When alfalfa, feather grass, and ryegrass were used, the risk of aphid infestation was lowered by 67% (P< 0.05). Collectively, the results indicated that mangold, ryegrass, and alfalfa were the optimal cover crops for sustainable wolfberry production in the study area. The use of appropriate forage cover crops enhanced plant growth and fruit quality of wolfberry by stimulating photosynthetic capacity and biotic stress resistance.

Effects of Different Microbial Fertilizers on Soil Quality and Maize Yield in Coastal Saline Soil

Microbial fertilizers have the characteristics of high efficiency and environmental protection in improving saline soils, and the application of functional microbial fertilizers is of great significance for the green abatement of saline barriers and the improvement of soil quality in coastal areas. The experiment was based on moderately saline soil in the coastal area of Hebei Province, with corn as the indicator crop, on the basis of conventional chemical fertilizer application. Different microbial fertilizer treatments, namely, T1 （conventional chemical fertilizer 750 kg·hm-2 + compound microbial agent 75 kg·hm-2）, T2 （conventional chemical fertilizer 750 kg·hm-2 + Bacillus megaterium 300 kg·hm-2）, T3 （conventional chemical fertilizer 750 kg·hm-2 + B. mucilaginosus 300 kg·hm-2）, T4 （conventional chemical fertilizer 750 kg·hm-2 + organic silicon fertilizer 600 kg·hm-2）, T5 （conventional chemical fertilizer 750 kg·hm-2 + bio-organic fertilizer 600 kg·hm-2）, T6 （conventional fertilizer 750 kg·hm-2 + active microalgae 15 kg·hm-2）, and CK （only fertilizer 750 kg·hm-2）, were used for these seven treatments, to study the effects of different microbial fertilizers on soil nutrients, salinity, bacterial community, and corn yield and economic efficiency during two critical periods （V12 stage and maturity stage） of corn. The results showed that compared with that in CK, T1 significantly increased soil total nitrogen （TN） and available phosphorus （AP） contents during the whole growth period. Over the whole reproductive period, soil organic matter （OM） at maturity increased by 10.35% over the V12 stage compared to that in CK, but there was no significant difference between treatments. Compared with that in CK, T5 and T6 significantly reduced soil total salinity and Ca2+ content during the whole growth period by an average of 14.51%-18.48% and 24.25%-25.51%. T1 significantly increased the bacterial diversity index over the whole growth period by 45.16% compared to that in CK. The dominant soil phyla were Actinobacteria, Proteobacteria, Acidobacteria, and Chloroflexi, and the dominant genera were Bacillus and Geminicoccaceae. The most abundant functions of the bacterial community in the study area were chemoheterotrophy and aerobic chemoheterotrophy, with average relative abundances of 28.89% and 27.11%, and T3 and T6 significantly improved soil N cycling function. The results of redundancy analysis （RDA） indicated that Na+, SO42-, pH, and EC were important factors driving the structure of the bacterial community, and correlation heatmaps showed that Na+, SO42-, pH, and EC were significantly and positively correlated mainly with the phylum Planctomycetota, whereas soil OM and TN were significantly and positively correlated with Cyanobacteria. Compared with that in CK, T6 increased the relative abundance of Cyanobacteria and optimized the bacterial community structure during the whole growth period. Using recommended dosages of bacterial fertilizers T1 and T6 increased maize yield by 7.31%-24.83% and economic efficiency by 9.05%-23.23%, respectively. The preliminary results of soil chemical properties and yield correlation analysis revealed that EC, AP, HCO3-, and Mg2+ were the obstacle factors limiting soil productivity in coastal areas. In conclusion, the use of the compound bacterial agent （T1） and active microalgae （T6） at the recommended dosage can significantly enhance soil nutrients, reduce salinity, and improve the structural diversity of soil bacterial communities, which not only ensures the increase in maize yield and efficiency but also realizes the efficient use of microbial fertilizers and the improvement of soil quality.

Effects of Replacing Chemical Nitrogen Fertilizer with Organic Fertilizer on Active Organic Carbon Fractions, Enzyme Activities, and Crop Yield in Yellow Soil

Taking the typical yellow soil in Guizhou as the research object, four treatments were set up： no fertilization （CK）, single application of chemical fertilizer （NP）, 50% organic fertilizer instead of chemical nitrogen fertilizer [1/2（NPM）], and 100% organic fertilizer instead of chemical nitrogen fertilizer （M）. The effects of organic fertilizer instead of chemical nitrogen fertilizer on organic carbon and its active components, soil carbon pool management index, soil enzyme activity, and maize and soybean yield in yellow soil were studied in order to provide theoretical basis for scientific fertilization and soil quality improvement in this area. The results showed that the replacement of chemical nitrogen fertilizer by organic fertilizer significantly increased soil pH, organic carbon （SOC）, total nitrogen （TN） content, and C/N ratio. Compared with those in the CK and NP treatments, the content and distribution ratio of soil active organic carbon components and soil carbon pool management index （CPMI） were improved by replacing chemical nitrogen fertilizer with organic fertilizer, and the effect of replacing chemical nitrogen fertilizer with 50% organic fertilizer was the best. Compared with those in the NP treatment, the 1/2 （NPM） treatment significantly increased the contents of soil readily oxidizable organic carbon （ROC333, ROC167）, dissolved organic carbon （DOC）, and microbial biomass carbon （MBC） by 22.90%, 8.10%, 29.32%, and 23.22%, respectively. Compared with those under the CK and NP treatments, organic fertilizer instead of chemical nitrogen fertilizer increased soil enzyme activities. The activities of catalase, urease, sucrase, and phosphatase in the 1/2 （NPM） treatment were significantly increased by 21.89%, 8.24%, 34.91%, and 18.78%, respectively, compared with those in the NP treatment. Compared with that of the NP treatment, the maize yield of the 1/2 （NPM） and M treatments was significantly increased by 44.15% and 17.39%, respectively. There was no significant difference in soybean yield among different fertilization treatments. Correlation analysis showed that soil SOC was significantly positively correlated with ROC333, ROC167, ROC33, DOC, MBC, and soil active organic carbon components, and CPMI was significantly positively correlated with soil organic carbon and its active components （P<0.01）. Corn yield was significantly positively correlated with soil enzyme activity, CPMI, total organic carbon, and its active components （P<0.05）. Therefore, from the perspective of yield increase and soil fertility, 50% organic fertilizer instead of chemical nitrogen fertilizer was conducive to improving soil quality and soil fertility, which is the key fertilization technology to achieve a high yield of crops in the yellow soil area of Anshun, Guizhou.

Emissions of CO2 and CH4 from Agricultural Soil with Kitchen Compost at Different Temperatures

Emissions of CO2 from the soil are mainly derived from soil microbial respiration, whereas CH4 emissions originate from anaerobic degradation of organic matter via microbial processes. Kitchen waste compost is used in the agricultural sector to improve soil quality. However, abiotic CO2 and CH4 emissions from soils amended with kitchen waste compost under aerobic conditions remain uncertain. Temperature plays an important role in organic matter decomposition in both biotic and abiotic pathways. This study aimed to evaluate biotic and abiotic emissions of CO2 and CH4 from soils receiving kitchen compost at different temperatures. Ten grams of soil amended with or without 0.1 g kitchen compost (1%) were sterilized or non-sterilized. The mixture and soil-only samples were incubated in 100-mL glass bottles at 20, 30, and 35 °C for 28 d under an aerobic condition. The results showed that CO2 and CH4 emissions increased at higher temperatures and compost application rates (p < 0.05). Emissions of CO2 mainly occurred via biotic pathways. Abiotic processes were potential pathways for CH4 generation, particularly at high temperatures of 35 °C. There was 20–24% of C in kitchen compost changed to CO2 and less than 0.1% to CH4. Our results suggest that global warming enhances abiotic CO2 and CH4 emissions and may contribute to further global warming.

Differences in Soil Fertility and Bacterial Community Structure Between Carbon Inputs such as Biochar and Organic Fertilizer and Their Relationship

The potato planting area of Guizhou Province ranks second in China. However, due to factors such as climatic conditions and unbalanced fertilization, soil organic matter in potato fields is consumed rapidly and has a large deficit, which affects soil biological function and soil fertility. Biochar and organic fertilizer are effective ways to supplement foreign aid organic matter to improve soil quality. However, the differences in soil fertility and microbial community structure and their relationships under the conditions of organic fertilizer or biochar combined with chemical fertilizer are not clear. In this study, three treatments of conventional fertilization （NPK）, increased application of biochar （NPKB）, and increased application of organic fertilizer （NPKO） were set up to investigate the characteristics of potato rhizosphere soil, bacterial community composition, and diversity； to analyze the effects of these factors on the soil integrated fertility index； and to explore the direct and indirect effects of IFI on soil fertility and bacterial community structure differences between treatments and their driving factors. The results showed that soil pH, available phosphorus （AP）, available potassium （AK）, total nitrogen （TN）, organic carbon （SOC）, and C/N ratio were significantly higher in the NPKB and NPKO treatments than in the NPK treatment （P<0.05）. Soil IFI was greatest for NPKO, followed by NPKB and least for the NPK treatment. A total of 8 214 ASVs were obtained from all the soil samples, belonging to 26 phyla, 75 classes, 165 orders, 176 families, and 251 genera （excluding unidentified fungi）. Proteobacteria, Actinobacteria, and Chloroflexi were the dominant phyla, accounting for 54.85% of all ASVs. Compared to that in the NPK and NPKB treatments, the NPKO treatment had the highest bacterial diversity and number of significantly different taxa, and soil AN, AP, AK, SOC, TN, and IFI were significant correlates of bacterial diversity index （P<0.05）. Additionally, pH, TN, and SOC were significant influencers of bacterial taxa differences （P<0.05）, with importance ranked as TN （70.59%） &gt; SOC （49.42%） &gt; pH （27.08%）. Structural equations suggested that pH-related soil properties and bacterial community diversity were the direct pathways influencing IFI, and soil pH-related soil characteristics could also indirectly affect IFI by affecting bacterial Shannon diversity. These results indicate that soil fertility and bacterial community structure were significantly different and correlated between the biochar and organic fertilizer addition treatments and that pH and bacterial community diversity were the key factors influencing IFI, with the NPKO treatment in particular having the best effect on improving IFI. Considering the effect of soil fertilization and the functional group of bacteria, NPKO is the recommended combination for the best synergistic effect of soil fertilization, that is, N 150 kg·hm-2+P2O5 135 kg·hm-2+K2O 135 kg·hm-2+organic fertilizer 6.6 t·hm-2.

Biostimulant and Arbuscular Mycorrhizae Application on Four Major Biomass Crops as the Base of Phytomanagement Strategies in Metal-Contaminated Soils.

Using contaminated land to grow lignocellulosic crops can deliver biomass and, in the long term, improve soil quality. Biostimulants and microorganisms are nowadays an innovative approach to define appropriate phytomanagement strategies to promote plant growth and metal uptake. This study evaluated biostimulants and mycorrhizae application on biomass production and phytoextraction potential of four lignocellulosic crops grown under two metal-contaminated soils. Two greenhouse pot trials were setup to evaluate two annual species (sorghum, hemp) in Italy and two perennial ones (miscanthus, switchgrass) in China, under mycorrhizae (M), root (B2) and foliar (B1) biostimulants treatments, based on humic substances and protein hydrolysates, respectively, applied both alone and in combination (MB1, MB2). MB2 increased the shoot dry weight (DW) yield in hemp (1.9 times more), sorghum (3.6 times more) and miscanthus (tripled) with additional positive effects on sorghum and miscanthus Zn and Cd accumulation, respectively, but no effects on hemp metal accumulation. No treatment promoted switchgrass shoot DW, but M enhanced Cd and Cr shoot concentrations (+84%, 1.6 times more, respectively) and the phytoextraction efficiency. Root biostimulants and mycorrhizae were demonstrated to be more efficient inputs than foliar biostimulants to enhance plant development and productivity in order to design effective phytomanagement strategies in metal-contaminated soil.

Technosol made with urban and industrial waste: Potential for improving soil quality and growing tree seedlings

This study evaluated the use of waste materials to produce Technosol, a "tailor-made" soil consisting of construction and demolition waste (CDW), solid waste from stone mining (WSM), natural soil (NS), and compost from plant pruning (CPP), for improving soil quality in forest recovery projects. Samples of CDW were characterized using X-ray fluorescence and X-ray diffraction. The potential of the Technosol as a substrate was assessed using a mixture of "Class A" CDW, WSM, NS, and CPP in the following proportions: (a) 10 % CDW + 42.5 % WSM + 42.5 % NS + 5 % CPP, (b) 20 % CDW + 37.5 % WSM + 37.5 % NS + 5 % CPP, and (c) natural soil as a control. A randomized block design was used with nine treatments and three replications using 5.5 L pots. The experimental treatments consisted of two proportions of mixtures, natural soil, and three tree species: pioneer, Cecropia pachystachya, secondary, Handroanthus impetiginosus and climax, Copaifera langsdorffii. The activity of the enzymes β-glucosidase and arylsulfatase was determined in the Technosol and natural soil at the end of the experiment. During 180 days, the height of the plants and the diameter of the stem were determined at intervals of 30 days and, at the end of the experiment, the aerial part dry mass (leaves and trunk) and roots were evaluated. The Technosol constructed from the mixture (a) proved to be viable for improving soil quality, as indicated by a greater enzymatic activity compared to other soils, and for the growth of H. impetiginosus seedlings, showing the capacity to gain plant height over 180 days after planting.

Deciphering spatial variability and dominant controls of soil quality under four types of grassland along a southeast-northwest transect in Tibet, southwestern China

Grasslands on the Qinghai-Tibetan Plateau are under threat from ongoing degradation due to natural and anthropogenic perturbations, resulting in widespread decline in the soil quality of grassland. However, the variations, distributions and dominant drivers of soil quality under different grassland types on the plateau have not been studied due to great difficulty in large-scale sampling at high altitudes. We quantitatively assessed soil quality under alpine meadow (AM), alpine steppe (AS), alpine desert steppe (ADS), and alpine desert (AD) along a 900-km southeast-northwest transect in Tibet, southwestern Qinghai-Tibetan Plateau using an improved soil quality index (SQI) approach. Results showed that there was a high spatial variability of SQI across the transect, with an overall increase of SQI from northwest to southeast (P < 0.01). The average SQI of AM (0.51 ± 0.12) and AS (0.47 ± 0.13) was significantly higher than that of ADS (0.33 ± 0.10) and AD (0.30 ± 0.10) (P < 0.05). Random forest analysis demonstrated that soil property, vegetation factors, environmental conditions and human activity exhibited a decreasing order of the relative importance on SQI. Interactions of soil property and vegetation factors significantly influenced SQI as indicated by the structural equation modeling (P < 0.05). Pedotransfer function (PTF) was applied to adequately predict the soil quality of grassland in Tibet (RMSE = 0.087, R2 = 0.647, P < 0.01), but an extrapolation of the established PTF for estimating grassland soil quality in another alpine region in northeastern Qinghai-Tibetan Plateau requires the nonlinear least squares correction to improve the prediction accuracy. This study unravelled the spatial variability and dominant controls of the soil quality of grassland in Tibet and established a high-precision forecasting model of SQI by considering the grassland type, providing a basis for accurately predicting and sustainably managing grassland soil quality in the alpine region. Reducing grazing intensity and vegetation restoration are needed to improve the soil quality of grassland on the Qinghai-Tibetan Plateau.

Soil Quality Assessment and Its Spatial Variability in an Intensively Cultivated Area in India

Intensive agricultural practices lead to a deterioration in soil quality, causing a decline in farm productivity and quality, and disturbing the ecosystem balance in command areas. To achieve sustainable production and implement effective soil management strategies, understanding the state and spatial variability of soil quality is essential. The study aims to enhance the understanding of soil quality variability and provide actionable insights for sustainable soil management. In this regard, principal component analysis (PCA) and digital soil mapping were used to assess and map the spatial variability of the soil quality index (SQI) in the Cauvery command area, Mandya district, Karnataka, India. A total of 145 georeferenced soil samples were drawn at 0–15 cm depth and analyzed for physico-chemical properties. PCA was used to reduce the dataset into a minimum dataset as eight important soil indicators and to determine relative weightage factors, which were used for assessing SQI with linear and non-linear scoring methods. For spatial assessment of SQI, the random forest algorithm with environmental covariates was used to map eight soil indicators selected in the minimum dataset. The soil property maps were subjected to linear and non-linear scoring, followed by multiplying with corresponding weightage factors and summation to produce SQI maps. Results reveal that values of SQI calculated using linear scoring, range from 0.10 to 0.64, with a mean of 0.39, while non-linear scoring exhibits a wider range of 0.12 to 0.78 and a mean of 0.48. With a slight higher sensitivity index of 6.5, non-linear scoring proved to be the better scoring method compared to linear scoring. Spatial assessment shows that the R2 and LCC between the calculated and predicted SQI were higher for non-linear scoring (0.66 and 0.66) compared to linear scoring (0.60 and 0.65). The SQI maps reveal high spatial variability with more than 40 percent of soils classified as moderate-to-low index. The soils with low SQI were distributed in eastern parts, whereas western parts exhibited high-to-very-high soil quality. To achieve production goals and improve soil quality in the eastern region, sustainable soil and crop management strategies must be developed, and their effects on soil quality should be assessed.

Green manuring improves soil quality, grain yield, and grain anthocyanin content in colored rice cultivated in tropical regions

AbstractGreen manuring is the process by which vegetative crops are incorporated into the soil, and it plays a good substitutable role in reducing chemical fertilizer applications while enhancing soil fertility. Field experiments were conducted at Lingao City of Hainan Province in 2020 and 2021, to evaluate the effects of in situ incorporation of different green manures (fallow (as control), rice, sesbania, and stylosanthes) on soil physical and chemical properties, nitrogen (N) uptake, grain yield, and the grain anthocyanin content in colored rice. Treatments included colored rice cultivated with previous fallow (T0), with previous rice straw manure (T1), with previous sesbania manure (T2), and with previous stylosanthes manure (T3). The seedlings of the colored rice variety Suixiangheinuo were transplanted 23 days after the incorporation of green manure. Our results indicated that both the grain yield and grain anthocyanin content of colored rice were significantly increased when green manure was incorporated into the soil compared to that of the control. Therein, grain yields of T1, T2, and T3 were increased by an average of 12.7%, 29.0%, and 24.5%, respectively, across 2 years in comparison with those of T0. And grain anthocyanin content in colored rice under T1, T2, and T3 was increased by 7.2%–7.5%, 13.9%–24.2%, and 9.8%–20.6%, respectively. In addition, in situ incorporation of leguminous green manure in the soil significantly increased soil fertility and partial factor productivity for N fertilizer. The above results suggested that colored rice crops should be followed in rotation with leguminous green manure, which was beneficial to increasing both grain yield and grain anthocyanin content of colored rice. This research elucidated that the incorporation of leguminous green manure sustained the production of colored rice in tropical regions, which was beneficial to reconcile the relationship between rice production and environmental protection.