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Soil amendments have been proposed as an effective way to enhance soil carbon stocks on degraded soils, particularly in dryland farming areas. Soil organic carbon (SOC) plays an important role in improving soil quality, and soil aggregates are known to be crucial in sequestering and protecting SOC. However, how aggregation and protection of SOC by aggregates respond to a single application of bentonite combined with maize straw remains unknown, especially in the sandy soil of a semi-arid region. A three-year field experiment with four treatments [no amendment (CK), maize straw amendment addition only (T1, 6 Mg ha−1), bentonite amendment addition only (T2, 18 Mg ha−1), and maize straw combined with bentonite amendment (T3, 6 Mg ha−1 maize straw plus 18 Mg ha−1 bentonite)] was conducted in the Loess Plateau of China to assess the effects of bentonite and maize straw on aggregation and SOC. The results indicated that soil bulk density decreased by 2.72–5.42%, and soil porosity increased by 3.38–8.77% with three years of T3 application, especially in the 20–40 cm layer, compared with CK. T3 increased the amount of C input, SOC stock, and SOC stock sequestration rate by 1.04 Mg ha−1 y−1, 0.84–1.08 Mg ha−1, and 0.49 Mg ha−1 y−1, respectively, and it increased the mass proportions and aggregate-associated C stock of >0.25 mm aggregates by 1.15–2.51- and 1.59–2.96-fold compared with CK. Correlation analysis showed a positive correlation of total SOC stock with the C concentration of >2 mm, 0.25–2 mm, and 0.053–0.25 mm aggregates. Aggregates of various sizes in sandy soils have the potential for greater SOC stock. Our findings suggest that the application of maize straw (6 Mg ha−1) combined with bentonite (18 Mg ha−1) would be an effective management strategy to enhance the bulk soil C pools by improving the soil structure and thereby improving soil fertility. [ABSTRACT FROM AUTHOR]

Soil amendments such as humic acid (HA), a biochar-based microbial agent (M), and vermicompost (V) can improve soil quality and promote crop growth. However, it remains unclear whether the co-application of the three soil amendments (HMV) has a synergistic effect on alleviating soil quality deterioration obstacles caused by dry sowing and wet emergence technology in Xinjiang cotton fields. A three-year field experiment was conducted in saline–alkali soils using plastic-film-mulched drip irrigation in Xinjiang, China. Through the orthogonal experiment method, the application amounts of HA, M and V were 75 kg ha−1, 75 kg ha−1 and 225 kg ha−1 respectively in 2021. In 2022, three application amount gradients were used for HA, M and V: 60 kg ha−1, 90 kg ha−1 and 120 kg ha−1 respectively. In 2023, the application amounts of HA, M, and V were 60 kg ha−1, 120 kg ha−1, and 120 kg ha−1. It should be pointed out that V contains HA in the range of 20–35%. This study aimed to explore the improvement effect of a single or combined application of HA, M, and V on soil quality and cotton emergence rate using dry sowing and wet emergence technology in Xinjiang cotton fields. The results showed that the single and combined applications of HA, M, and V improved the soil quality and water–heat–salt environment of the cultivated layer. In the combined application, the cotton seedling emergence rate and yield increased by 1.9–22.8% and 7.0–54.1%. Therefore, it is recommended to jointly apply HA, M, and V to promote cotton seedling emergence and increase yield using dry sowing and wet emergence technology in Xinjiang cotton fields. [ABSTRACT FROM AUTHOR]

The residual effect of compost and biochar amendment on soil properties and durum wheat response was evaluated under field conditions in a Mediterranean environment. The treatments compared in a randomized complete block experimental design with three replications were: mineral fertilizer (100 kg N ha−1), compost applied at the rate of 25 Mg ha−1, biochar applied at the rates of 10 and 30 Mg ha−1, unfertilized control. Wheat was the second crop included in a sorghum–wheat cropping system and did not receive fertilizer supply. A hierarchical statistical analysis was carried out to investigate how different treatments could impact the cropping system performance. The findings highlight the significant influence of soil properties, particularly total N, WEOC, and TOC, on wheat and protein yield. One year after the amendment and fertilizer application, compost and biochar significantly increased soil total organic carbon content. The highest soil water extractable organic carbon was found with the compost application (76.9 mg kg−1), whereas the lowest value (50 mg kg−1) was with the highest rate of biochar. Soil respiration rates and hydraulic properties were not affected by the investigated treatments. This behavior is probably related to the short experimental duration and to the silty clayey soil texture. Significant correlations were observed between bulk density and water content at pressure heads in the −20 and −100 cm range; this range accounts for the effect of soil macro and mesopores. Multiple linear regression analysis revealed strong predictive power for grain (R2_adj = 0.78; p < 0.001) and protein yield (R2_adj = 0.77; p < 0.001). The highest grain yield (3.36 Mg ha−1) was observed with compost, and the lowest (2.18 Mg ha−1) with biochar at a rate of 30 Mg ha−1. These findings lay the basis for understanding how different soil amendment management may impact soil quality and wheat performance, even in consideration of climate change. [ABSTRACT FROM AUTHOR]

Reducing fertilizer doses under sustainable agricultural management is possible by increasing nutrient utilization efficiency, which will decrease crop production costs and boost economic return. Soil amendments known as water retention agents (WRAs) are added to the soil to enhance crop growth conditions. We hypothesize that the addition of WRAs may support the soil-retaining nutrients given through fertilization and prevent them from leaching into tropical soils characterized by severe rainfall due to WRAs' exceptional capacities to absorb and store water. Mango trees (Mangifera indica L. cv Tainong No. 1) aged 18 years were fertilized with 100% or 80% of the recommended doses of nitrogen (N), phosphorus (P), and potassium (K). The experimental design included three treatments, i.e., complete recommended doses of N, P, and K (CRF), 80% of the complete recommended doses (RRF), and water-retaining agent (40 kg ha−1) + 80% of the complete recommended doses (WRARRF). Reducing the fertilization doses by 20% for mango trees in the studied tropical soil significantly (p < 0.05) minimized the nutrient availability in the soil compared to the complete fertilization doses. WRARRF compensated for the nutrient reduction by increasing the availability of N, P, and K. The addition of WRARR increased N, P, and K in mango leaf by 11%, 4%, and 7% in the first year and by 11%, 6%, and 7% in the second year, respectively, compared to CRF. The addition of WRARR increased the partial fertilizer productivity (PFP) value by 36% and 41% in the first and second years, respectively. The highest mango fruit output was achieved by the addition of WRARRF, which resulted in increases in mango fruit yield of 11.9% and 16.5% in the first and second years, respectively, compared to RRF. Fruit quality traits showed the descending order: WRARRF > RRF > CRF. WRARRF produced the maximum economic benefit (USD 7372 per hectare) compared to CRF and RRF. The polyacrylamide/attapulgite water-retaining agent exhibited remarkable improvement in mango fruit yield and economic profit by regulating the release of nutrients in tropical soils. Water-retaining agents are an effective strategy for overcoming the extensive fertilization used in mango orchards, which has resulted in numerous environmental contaminations and the inefficient use of fertilizers. [ABSTRACT FROM AUTHOR]

Biochar and plant growth-promoting rhizobacteria (PGPR) are widely used as an amendment for soil physicochemical properties and soil bacterial community diversity. In Guangxi, China, we carried out a study to determine how PGPR and biochar influence the soil's environmental stability in an Eucalypt plantation. We applied biochar and PGPR in a contrasting application manner to an acidic red loam soil. Thus, three treatments were set up as 5 × 1010 CFU·mL−1 PGPR-only (MB0), 20 t·hm−2 biochar-only (B20), and co-application of 20 t·hm−2 biochar and 5 × 1010 CFU·mL−1 PGPR (MB20), as well as no biochar and no PGPR (M0B0). Our results indicated that MB20 significantly decreased the soil total nitrogen (TN) and increased the soil total phosphorus (Soil TP), soil ammonium nitrogen (NH4+), and soil water content (SWC) when compared with the control. The MB20 also significantly increased the Simpson, ACE, and Chao indices of the soil bacterial community's diversity relative to the control. We also observed a significant effect of the Soil TN on both the bacterial community and the functional diversity in soil. These findings may indicate that assessing the soil N status is expected to be an essential indicator of the soil microenvironment's response to biochar and PGPR applications. [ABSTRACT FROM AUTHOR]

This document provides a summary of various research articles on the topic of humic substances (HS) and their applications in different fields. The articles explore the molecular properties of HS, their impact on soil fertility and plant growth, methods for their quantification, and their role in environmental remediation. The studies highlight the potential of HS as organic fertilizers, soil amendments, and biostimulants, and discuss their effects on enzyme activity, plant quality, and nutrient availability. The research also delves into the molecular structure of HS, their interactions with other compounds, and their ability to adsorb harmful substances from water and soil. Overall, these articles contribute to the growing body of knowledge on HS and their diverse applications. [Extracted from the article]

The soil in a lead–zinc mining area, contaminated with heavy metals like cadmium (Cd) and lead (Pb), poses a risk to crops such as maize. Experiments using biochar and sepiolite as soil ameliorants in potted maize showed these substances can mitigate heavy metal contamination. Biochar increased potassium and phosphorus in the soil and maize, while sepiolite significantly boosted overground phosphorus by 73.2%. Both ameliorants transformed Cd and Pb into a more stable state in the soil, reducing their accumulation in maize, especially with biochar, which effectively inhibited metal migration during leaching events. This study provided insights for further improvement of soil amendments and multi-factor application experiments. [ABSTRACT FROM AUTHOR]

The efficient use of organic amendment (OM) is considered an economic, environmental and sustainable practice to improve soil quality, especially the accumulation of organic carbon (C) and water use efficiency (WUE) in dryland agriculture. However, the effect of different OM on soil nutrients, organic carbon fractions, water content and maize yield is unclear in arid and semi-arid regions with sandy soil. Field experiments with four OM, grass peat (GP), biochar (BC), organic fertilizer (OF) and maize straw (MS), were conducted with an equivalent amount of C input on the southeastern edge of Mu Us Sandy Land in China. Results indicated that the soil nutrients and labile organic carbon (DOC, MBC, KMnO4-C and POC) concentrations were higher under OM (GP, BC, OF and MS) treatments than in CK in the 0–0.10 m soil layers. GP treatment remarkably improved carbon pool index values (1.63, 2.51 and 2.24, respectively) in all layers compared to CK (1.00). At maturity stages of maize, the soil water content (SWC) under GP and OF treatments (11.3–13.4%) was remarkably higher than that in CK treatment (around 10.0%). Yield and WUE were remarkably greater in GP and OF treatments compared to CK. The results proved that GP amendment is superior for barren sandy soil than BC, OF and MS treatments in improving soil nutrients, organic carbon sequestration, WUE and crop yield in China. [ABSTRACT FROM AUTHOR]

Soil degradation due to loss of soil organic carbon is a serious concern in semiarid agroecosystems. Biochar and other organic char products have long been known to increase soil organic carbon. In this study, three-year field observations were carried out on use of coal char (CC) and biochar (BC) as soil amendments in unirrigated semiarid rangeland soil. Coal was pyrolyzed at three different temperatures of 650, 750, and 800 °C to form CC650, CC750, and CC800, respectively, and BC was obtained from a local commercial producer. Manure, CC, and BC were incorporated in soil at 10% (v/v). Analyses of plant growth (aboveground biomass) and soil properties were performed and compared with the control treatment without char. In all three years, CC applied with manure (CC650M) produced significantly greater grass biomass, by 95, 42, 101%, and BC applied with manure (BCM) increased grass biomass by 89, 39, 52% in 2018, 2019, and 2020, than the controls in the respective years. Soil tests a year after application of char indicated significantly increased soil organic matter (OM) with CC and BC treatments (1.60–2.93%) compared with the control (1.37%). However, further detailed studies are required to investigate CC and BC interactions with soil in unirrigated semiarid rangelands. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization (HTC) is a proven cost-effective and energy-efficient method for waste management and value-added product recovery. There are, however, several issues that require further improvement or research. Identifying the strengths and weaknesses of HTC in comparison to traditional pyrolysis is crucial for scientists to choose between them or use both (complementary) to achieve specific product properties. Additionally, sharing information on diverse modeling approaches and scales is crucial to enhance the robustness and universality of HTC process models. In addition, the study on the applicability of hydrochars on target applications such as soil amendment is crucial to give back nutrients to soils and face the dependence on finite specific feedstocks in this field. Also, proper management of the process by-products, especially process water, must be addressed to improve the carbon and hydric footprint of the process. Reviewing the suitability of HTC to treat specific challenging wastes, whose strength is not related to their calorific value but to their nutrient composition (i.e., manures), is also an appealing topic for HTC research. This paper aims to tackle the above-mentioned issues through an updated review and discussion of research gaps that require further investigation. [ABSTRACT FROM AUTHOR]

The impacts of two different cover crop (CC) strategies, as well as compost, silicon (Si), and biocontrol (BC) soil amendments were evaluated on soil chemical and biological properties, crop development and yield, and disease and pest issues in organic vegetable production, as represented by legume (green snap bean), cucurbit (green zucchini squash), and solanaceous (sweet pepper) vegetable crops, in a three-year field trial in Maine, USA. A multi-species CC mixture (6 crops, including legumes, grasses, and brassicas) was compared with a standard winter rye CC for potential benefits on soil properties and biomass production. Soil amendments included a commercial organic fertilizer alone, composted dairy manure, compost plus BC (commercial formulations of Trichoderma and Streptomyces spp.), and compost plus Wollastonite, a natural source of Si. Poor stand establishment of some components of the multi-species CC mixture resulted in lower biomass and ground cover relative to winter rye, but had no effect on crop development or yield. Compost amendments increased soil pH, organic matter, and nutrient contents, as well as yields of bean, zucchini, and peppers relative to a fertilizer-only treatment. Additions of Si increased Si content in plant leaves and reduced powdery mildew on squash and leaf necrosis of beans. In the absence of substantial soilborne disease, BC provided only marginal reductions in powdery mildew and leaf necrosis and no effects on yield. These results help define specific management practices to improve organic vegetable production and provide useful information and options for growers. [ABSTRACT FROM AUTHOR]

The composition of microbial communities and the functioning of ecosystems are greatly influenced by the nutrient inputs. Despite this fact, our knowledge regarding the impact of phosphorus (P) inputs on soil P availability and microbial community structures in subtropical acidic soils remains limited. We hypothesized that diverse P inputs, incubation temperatures, and soil types could significantly alter soil P availability and microbial communities. To address this gap, we conducted a laboratory incubation experiment, investigating the effects of biochar and inorganic P amendments on soil available P, soil pH, acid phosphatase enzymes, and bacterial abundance. We employed two different incubation temperatures (15 °C and 25 °C) using acidic paddy soil and red soil from the subtropical Southern China region. Our results indicate a notable increase in soil pH, reaching 37% and 39% at 15 °C and 40% and 40.6% at 25 °C, respectively, following the application of biochar and inorganic P amendments in paddy soil. In the case of red soil, we observed pH increases of 41% and 43% at 15 °C and 44% and 45% at 25 °C after the application of biochar and inorganic P amendment, respectively. The addition of inorganic P amendment resulted in the highest available P contents in paddy soil, reaching 111.47 mg/kg at 15 °C and 100.17 mg/kg at 25 °C, respectively. However, Proteobacteria decreased after inorganic P addition, which showed that P might not be the only limiting nutrient for various bacterial communities. Bacterial diversity and richness indices were found to be higher after biochar application in both soils. Gemmatimonadetes, Acidobacteria, and Actinobacteria were found to be strongly influenced by incubation temperatures, whereas most of the top abundant bacterial phyla, such as Gemmatimonadetes, Actinobacteria, Chloroflexi, Acidobacteria, Planctomycetes, Firmicutes, Patescibacteria, and Bacteroidetes, were highly dependent on soil type. At the genus level, various important P solubilizing genera (Pseudomonas, Bradyrhizobium, Streptomyces jietaisiensis, Massilia) significantly increased after biochar and inorganic P addition in both soils. The correlation analysis proved that P-solubilizing genera were significantly associated with changes in soil pH, as well as soil available P after biochar and inorganic P addition. Conclusively, in a short-term incubation experiment, inorganic P amendment greatly increased the soil pH and available phosphorus contents compared to biochar and control treatments; however, the microbial community was observed to be strongly associated with biochar application, soil type, and incubation temperature. [ABSTRACT FROM AUTHOR]

Properly chosen soil management practices can stabilize the nutrient regime in the soil, including the mobility and bioavailability of hazardous elements. This study aimed to identify the optimal soil management practices in a productive vineyard on Rendzic Leptosol in the Nitra wine region (Slovakia). Soil samples were collected each spring from two depths, 0–30 cm, and 30–60 cm, with the following treatments: T—soil tillage, P + FYM—plowed farmyard manure, G—grass strips, G + NPK1—first-level fertilization, and G + NPK2—second-level fertilization, from 2019 to 2023. The results indicated that more pronounced changes in soil properties occurred in the 0–30 cm layer. Higher NPK rates significantly affected soil sorption capacity and decreased soil pH when compared to other treatments. While G + NPK2 showed the highest storage of total N, S, P, K, and available P and K, it exhibited the lowest levels of total and available Ca. The T treatment displayed the lowest storage of C, N, S, P, and available K. In terms of hazardous metals (Cr, Ni, Pb, and Zn) none exceeded the limiting values in any of the soil management practices. However, in the 0–30 cm layer, Cu concentrations exceeded the limits set by Slovak Republic regulations in the T, P + FYM, G, G + NPK1, and G + NPK2 treatments by 62.6, 73.7, 70.2, 82.1, and 102.9 mg kg−1, respectively. Additionally, as total C increased, Cr concentration was observed to decrease with correlation (r = −0.46). Positive correlations were found between total C and Zn, as well as CaCO3 and Zn in the 0–30 layer. [ABSTRACT FROM AUTHOR]

Cigar tobacco, an economically important cash crop, holds a substantial role within the fiscal framework of the national economy. This crop, however, is characterized by a marked vulnerability to pathogenic bacteria, culminating in consequential financial loss throughout its cultivation phase. Plant growth-promoting rhizobacteria (PGPR), a salient class of advantageous bacterial flora, are recognized for their ability to enhance plant growth, inhibit deleterious pathogens, and synthesize compounds that either have a direct impact on plant morphogenesis or activate otherwise ineffectual soil components. Through these mechanisms, PGPR augments the soil's nutritional profile, making it more receptive to plant uptake, thus stimulating vegetative growth. The Bacillus subtilis microbial fertilizer, the prime exemplar of PGPR, demonstrates not only a pathogen-suppressive effect but also an induction of the plant's innate disease resistance mechanism. This bolsters the plant's resilience to disease fosters a probiotic milieu within the soil, and catalyzes the formation of agglomerate structures, all of which contribute to enhanced soil fertility and moisture retention, increased soil friability, and the facilitation of root expansion. In this study, a controlled pot experiment was conducted to elucidate the mechanism through which inter-root probiotics rehabilitate the soil's ecosystem and foster crop growth in cigar tobacco seedlings afflicted with root black rot bacteria. Four treatments were instituted, including CK: a blank control (no microbial application); A: probiotic only (Bacillus subtilis microbial fertilizer); B: both pathogenic and probiotic (the Bacillus subtilis microbial fertilizer together with root black rot pathogen); C: pathogenic only (the root black rot pathogen). Our empirical findings delineate that the presence of pathogenic bacteria deteriorates the soil environment, thereby constraining the transmutation of soil nutrients and their subsequent assimilation by plants. This severely impedes the vegetative development of cigar plants. By contrast, the application of a PGPR microbial fertilizer modified the soil microbial community structure, exhibiting an antagonistic interaction with the indigenous pathogenic bacterial species. Relative to the CK treatment, the application of the Bacillus subtilis microbial fertilizer was found to invigorate the catalytic conversion of soil enzymes, incrementing the peroxidase, acid phosphatase, urease, and sucrase activity by 12.98%, 19.55%, 13.57%, and 17.91%, respectively. Meanwhile, it was observed to ameliorate the soil's physicochemical attributes, enhancing the available content of nitrogen, phosphorus, and potassium by 4.52%, 6.52%, and 15.14%, respectively, along with the augmentation of soil organic matter content by 17.33%. The fortification of soil physicochemical properties and the enrichment of soil fertility, as a result of the PGPR microbial fertilizer application, translated into a robust 57.23% enhancement of root vigor and a 60.47% extension of the root length of cigar tobacco seedlings. These soil amendments subsequently fueled an uptick in the growth parameters of cigar plants, including increases in plant height, stem girth, leaf count, maximal leaf dimensions, and both the fresh and dry weight of cigar tobacco. [ABSTRACT FROM AUTHOR]

Effective weed management faces increasing legislative restrictions for the use of herbicides due to their toxicity and environmental persistence. In addition, the linear increase in resistant weeds threatens to render authorized herbicides useless. In a post-herbicide era, under the IWM strategy, allelopathy can play a relevant role since many plants can produce a variety of allelochemicals with different structures and modes of action, capable of inhibiting the germination and growth of different weed species. Inspired by green manuring with cover crops, the use of allelopathic biomass from weeds, invasive species, residues of forestry plantations, and other abundant wild plants has some advantages over green manures grown in situ or other alternatives such as applying plant extracts or essential oils. Beyond the ecosystem services provided by green manures, the potential use of allelopathic biomass offers extra opportunities for the science and practice of holistically integrated weed management because (i) the investment of resources and time for producing cover crops would be alleviated, and (ii), new use of agroforestry residues and a sink for harmful weed biomass is provided. In this review, we compile the current knowledge of those allelopathic species whose biomass, used as soil amendment, effectively controlled weeds. In addition, the complex allelopathic processes underlying the effectiveness of cover crops and allelopathic biomass used as green manures for weed control are revisited. [ABSTRACT FROM AUTHOR]

With the global population continuing to increase, the demand for food and energy has escalated, resulting in severe environmental pressures. Traditional methods of food and energy production have left a significant footprint on the environment, primarily due to the emission of greenhouse gases and a notable surge in waste production. Nevertheless, scientists have recently focused on developing sustainable solutions by managing biomass waste and converting it into useful products. Various biomass conversion technologies, including pyrolysis, gasification, and fermentation, have emerged to transform waste materials into valuable commodities like biofuels, fertilizers, and chemicals. These technologies present an alternative to conventional energy production methods and decrease reliance on non-renewable resources. Furthermore, the by-products generated through biomass conversion, such as biochar, possess utility as valuable soil amendments. This review emphasizes the potential of biomass conversion technologies in providing sustainable solutions for waste management, food and energy production, and reducing negative environmental impacts while providing valuable by-products for agricultural use. The focus is on Lebanon, which is facing a waste and energy crisis, with an aim to encourage and promote sustainable practices by highlighting different green waste management technologies. Focusing on the application of biochar in soil, our goal is to provide cost-effective and eco-friendly solutions to various agricultural and environmental challenges in Lebanon. This includes using biochar from biomass waste as a soil amendment to boost crop yields, remediate soil pollution, reduce soil drought stress, and address other related issues. [ABSTRACT FROM AUTHOR]

In a field experiment, composted coffee waste (CW) was used as soil amendment at three different rates (2%, 4%, and 8%) in plots cultivated with wheat; the effects on the soil nematode community and plant growth were studied. By sampling twice, i.e., three and six months after the application of treatments (3MAA and 6MAA), the duration of these effects was also evaluated. Treatment using composted coffee waste (CW) led to an increased abundance of all soil nematodes, especially of bacterivores and fungivores, probably via a bottom-up effect of CW on the soil community. The most-affected genera were the enrichment opportunists Panagrolaimus and Rhabditis, which increased after CW addition in a dosage-dependent way at 3MAA, while at 6MAA they were replaced by general opportunists, mainly bacterivorous and fungivorous genera; a nematotoxic effect of CW was also observed in the 6MAA condition. The nematode indices and the metabolic footprint indicated an enriched and vigorous soil three months after CW addition and a lower enrichment status of the soil together with a higher fungal participation in the decomposition pathway six months after treatments. However, in the 6 MAA condition, the soil nutrient values were higher in the CW-treated plots. None of our treatments inhibited or enhanced plant growth. [ABSTRACT FROM AUTHOR]

The Quick Wash (QW) treatment extracts phosphorus (P) from manure and municipal sludge (MS), producing an organic acidified by-product with adequate nitrogen (N):P ratio to meet crop N requirements. Yet, data on crop response to N using QW by-products are lacking. We evaluated the response of annual ryegrass (Lolium multiflorum Lam.) and potential N leaching in sandy soil to N applications using raw wastes, their corresponding QW by-products, and ammonium sulfate (AMS) fertilizer. Treatments included a control (no amendment added), raw and acid-washed chicken litter, dairy and swine manure, MS, and AMS at 100, 200, and 400 kg N ha−1. We found no significant differences in annual ryegrass yield and N uptake between the raw and acidified organic QW by-products. However, ryegrass produced 4–30% more biomass with AMS than organic amendments. The total residual soil inorganic N under AMS treatments ranged between 6.3 and 67.9 mg pot−1 and accounted for 5–17% of the total N applied, but it was <1% for all the organic amendments. We found no differences in soil N leaching between raw and acid-washed forms of each organic soil amendment. Our results indicated that acidified organic QW by-products can improve environmental quality by substantially reducing the amount of applied P with no penalties for crop yield losses compared to raw manure and MS. [ABSTRACT FROM AUTHOR]

The availability of cadmium (Cd) in soils is an important factor affecting the safe production of crops. The application of certain soil amendments could reduce the soil Cd availability via the passivation of Cd. However, the passivation of Cd in alkaline soils is limited. Thus, different inorganic and organic amendments and their compound treatments were selected as passivators for reducing the Cd availability in a weakly alkaline farmland soil. The effects of different single and compound amendments on the soil pH and Cd availability, as well as the interactions between inorganic and organic components in immobilizing Cd, were evaluated. The results showed that the inorganic–organic compound amendments can considerably improve the Cd passivation efficiency in the weakly alkaline soil. Moreover, the inorganic and organic components in the compound amendments exerted different synergistic effects in Cd passivation. The manganese dioxide-based compound amendments showed the most remarkable synergistic effects, while the calcium–magnesium–phosphate fertilizer-based compound amendments displayed the weakest synergistic effects. The underlying mechanisms regarding the synergistic effects may be that the compound amendments enhanced the adsorption/specific adsorption, co-precipitation, and surface complexation of Cd in the alkaline soil. A more balanced recommendation for Cd immobilization in the weakly alkaline soil may be manganese dioxide-based compound amendments, given the synergistic effects and Cd immobilization capabilities of various compound materials. This study may provide a theoretical foundation for the passivation remediation of alkaline Cd-contaminated farmland soils by using inorganic–organic compound amendments. [ABSTRACT FROM AUTHOR]

Two of the most significant issues confronting arid and semi-arid countries are soil degradation and the need to reclaim sandy soils and improve their properties to enhance the agricultural area and ensure food security. Many attempts to improve sandy soil properties have been attempted using soil amendments, but further research is needed to explore the combined impact of cost-effective amendments. To that purpose, we investigated the impact of various soil amendments, including single and combination applications of synthetic Super Absorbent Polymer (SAP), compost, and biochar, on sandy soil physiochemical characteristics and bean (Vicia faba L.) production and quality throughout three growing seasons. In a randomized complete block design with three replicates per treatment, different treatments such as control (without application), lower dose of SAP (SAP1), higher dose of SAP (SAP2), biochar, compost, SAP1 plus biochar, SAP1 plus compost, SAP2 plus biochar, SAP2 plus compost, and biochar plus compost were used. The combined treatments, such as SAP2 plus biochar (T8), SAP2 plus compost (T9), and biochar plus compost (T10), improved soil physiochemical characteristics and crop production significantly. Application of T10 decreased soil bulk density by 15%, 17%, and 13% while increasing soil available water by 10%, 6%, and 3% over the first, second, and third growing seasons, respectively, compared to untreated soil (T1). The application of treatment (T9) surpassed other treatments in terms of yield, quality, and economic return, significantly increasing the seed yield by 24%, 26%, and 27% for the first, second, and third season compared with untreated soil. The higher rate of polymer combined with compost could be considered a cost-effective soil amendment to improve sandy soil productivity in arid and semi-arid regions. [ABSTRACT FROM AUTHOR]

Manure, a globally used soil amendment, can contribute to excessive N and P runoff, leading to water pollution. Biochar (BC) shows promise in mitigating nutrient loss by retaining soil nutrients. However, there is limited research exploring the combined effects of tillage practices, biochar, manure, forage crops, and soil types on soil nutrient characteristics in a single field study. Our objectives are to determine if, in North Central Texas, differing soil types, soil amendments, forage crops, and tillage practices affect soil nutrients when applied short term, and whether correlations exist among soil nutrient characteristics as affected by soil amendments, tillage practices, and the presence of forage crops. The study encompasses three field sites with five factors, including soil types, manure rates, biochar rates, tillage practices, and forage crop types. Soil samples were assayed for pH, electrical conductivity (EC), macronutrients, and micronutrients. Data analyses involved variance analysis, Fisher's tests, and Pearson's correlations using R in Rstudio (the IDE). Microplots treated with manure (average 2.16 ppm) retained 60% greater average nitrate levels at the end of the growing season than those treated with a synthetic fertilizer (average 1.35 ppm) (p ≤ 0.05). Moderate and strong correlations were observed between EC and S (r (106) = 0.43, p < 0.001 in loamy sand soil; r (106) = 0.80, p < 0.001 in clay loam soil) and between nitrate and Zn, (r (106) = 0.36, p < 0.001 in loamy sand soil; r (106) = 0.44, p < 0.001 in sandy loam soil) across different soil types. Soil type (texture) emerged as the primary influencing factor on plant-available soil nutrients and characteristics, followed by manure application and tillage practices. The impact of BC and forage crop type varied depending on other experimental factors. Understanding the influence of soil type, amendment application, and tillage on soil nutrient characteristics can guide sustainable forage production practices and soil nutrient management strategies. [ABSTRACT FROM AUTHOR]

Polyacrylamide (PAM) is a water-soluble polymer with strong cohesiveness and a strong water absorption capacity, and it has been widely used to modify soil structural stability. However, little information is available on the impact of PAM application on the aggregate-breaking process of purple soils in hilly areas of southwestern China. Therefore, the current study aimed to examine the influence of PAM application on the aggregate stability of purple soil in terms of different breakdown mechanisms at different hillslope locations. Three disruptive tests employing the Le Bissonnais method (FW, fast-wetting sieving; SW, slow-wetting sieving; and WS, wet-stirring sieving) were used to determine the mean weight diameter (MWD), geometric mean diameter (GMD), and mass fractal dimension (D) of the soil aggregates, and soil erodibility factor (K) was calculated as an index of soil anti-erodibility. Overall, the major aggregate-breaking mechanism for purple soils was the following: SW (differential swelling) > WS (mechanical breakdown) > FW (slaking). The content of water-stable aggregates (>0.25 mm) obviously rose after PAM application, with the most significant influences shown under FW. A significant difference in MWD was observed between PAM application and without polyacrylamide application (CK) under WS (p < 0.05). However, there was a significant difference in GMD between PAM and CK (p < 0.05) under FW and SW. In comparison with CK, D value in PAM under FW and SW was significantly reduced, mainly at the slope locations of 0 and 20 m. A descending order of FW, WS, and SW was found on the basis of K value at different slope locations. These findings contribute to improved understanding of proper application of soil amendments to control soil and water loss in purple soils. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Soil amendments with composted organic materials are recommended to increase soil organic matter (SOM) and promote soil fertility. Growing areas of hedged olive groves in the southern Iberia peninsula generate huge amounts of olive leaves, and their potential as an organic soil amendment is not fully studied. An experimental field trial in a hedged olive grove ("Cobrançosa") was set up near Portalegre, Portugal, to test a compost of olive leaves plus sheep manure (with a ratio of 2:1) when applied in a row at the soil's surface. Nominal rates of zero, 2.5, and 5.0 kg m−2 (T0, T1, and T2, respectively) were applied in a complete randomized block setup (three treatments, three replicas, and nine plots), and soil properties of layers between 0–5, 5–15, and 15–30 cm were annually monitored. More expressive results occurred in the soil layer 0–5 cm, and with the dosage T2. After one year, there were significant increases in the total N, carbon of the particulate organic matter, permanganate oxidizable carbon (POX-C), extractable phosphorus, and zinc. After two years, there was 16% more soil organic carbon (SOC), an absolute increase of 0.5 in pHKCl, 1.9 times more extractable phosphorus, and ten times more zinc. The soil's C-stock in the 0–30 cm layer, after two years of T1 and T2 dosages, was 0.11 and 0.35 kg m−2 (~3 and ~9%, respectively), which was higher than with T0. POX-C was the most sensitive SOM-related indicator, showing increases of up to 30 cm deep after one year. This compost improved soil fertility but should be monitored over longer periods of time. [ABSTRACT FROM AUTHOR]

The application of biochar as an environmentally friendly additive for agricultural soils has recently gained significant attention. However, the influence of biochar addition on unsaturated hydraulic behavior at high suction ranges (i.e., exceeding 100 kPa) remains largely understudied. This study investigates the impact of biochar addition on the unsaturated hydraulic properties of biochar amended soil (BAS). The effects of biochar content, particle size, and soil compaction on the unsaturated hydraulic properties of BAS were also considered. Peanut shell biochar was utilized in this investigation and was amended into a compacted silty sand with distinct particle size groups. Soil water retention curves and unsaturated permeability were measured through a series of evaporation tests. Results demonstrate that the impact of soil compaction on the unsaturated hydraulic properties of BAS diminishes at high suction range, regardless of biochar particle size and content. A high degree of compaction reduces the saturated permeability of BAS by minimising soil macropores. On the other hand, incorporating high biochar contents with fine particles into the soil enhances the reduction of unsaturated permeability and the improvement of water holding capacity, thereby making biochar an effective application in soil for sustainability of the agroecological environment. [ABSTRACT FROM AUTHOR]

To monitor soil biological quality, it is of paramount importance to assess how chemically diverse organic residue amendments reciprocate to organic matter. The present incubation study aimed to evaluate the effect of organic residue amendments varying widely in their biochemical composition on the dynamics of soil enzymatic activity. The changes in the pattern of soil enzymatic activity have been monitored over a period of 63 days using a total of eleven different crop residues. The enzyme activity (dehydrogenase, fluorescein diacetate hydrolysis, acid phosphatase, alkaline phosphatase and phytase) in soils amended with chemically diverse organic residues were significantly higher as compared to the control. It was further observed that the enzymatic activities in Azadirachta indica, Avena sativa and Lens culinaris continued to be higher up to 28 days after their incorporation (DAI). Our study showed that plant residues varying in different cellulose and hemicellulose contents influenced the enzymatic activities as well as functional diversity of soil microbial communities. [ABSTRACT FROM AUTHOR]

Straw incorporation is known as an environmentally friendly agricultural practice that can effectively enhance soil nutrient contents and crop yields; its potential to suppress soil-borne disease has also been reported in recent years. Here, we perform a field experiment for two consecutive years (2017–2018) to evaluate the effectiveness of maize (Zea mays), rice (Oryzae sativa L.) and wheat (Triticum aestivum L.) straws incorporation in alleviating Chinese cabbage (Brassica rapa L. ssp. pekinensis) clubroot disease caused by Plasmodiophora brassicae Woronin. Microbial composition in Chinese cabbage rhizosphere and soil P. brassicae abundance were estimated by high-throughput amplicon sequencing and quantitative polymerase chain reaction (qPCR). Results showed that, during the two-year field experimental cycle, all three straw amendments promoted Chinese cabbage plant growth, inhibited clubroot disease and increased the alpha diversity of the bacterial community in Chinese cabbage rhizosphere. Rice and wheat straws also increased the alpha diversity of the fungal community. These straws diversified the composition of the Chinese cabbage rhizosphere microbial community. All three straws promoted Cryptococcus carnescens; both rice and wheat straws stimulated Lysobacter sp.; maize straw boosted Sphingomonas sp. and wheat straw increased Talaromyces sp. These microbial taxa are either considered to have positive influences on plant growth or potential biocontrol effects. In addition, straw amendments also increased soil pH, electrical conductivity, available nitrogen and available potassium contents in both years of the field experiment. Taken together, we concluded that these three gramineous straw amendments ameliorated Chinese cabbage rhizosphere microorganisms, inhibited clubroot disease and promoted the growth of Chinese cabbage, and that rice straw worked best amongst the three. This study could potentially provide a new tactic of massive grain crop straw utilization and a direction in dealing with clubroot disease. [ABSTRACT FROM AUTHOR]

Given that rice husk biochar has been shown to modulate salinity in salt-affected acid soils, the objective of this study was to investigate the effects of organic amendment of salinized acid soils on P fractions, enzyme activities, and associated rice yield. Four treatments, viz. Rice–Rice–Rice, [RRR]; Fallow–Rice–Rice, [FRR]; Fallow–Rice–Rice + 3 Mg ha−1 of compost [FRR + Comp]; and Fallow–Rice–Rice + 10 Mg ha−1 of biochar [FRR + BC] were established at Ben Tre and Kien Giang sites, Viet Nam, over six consecutive crops. Soil properties at harvest of the sixth crop showed that there were diverse patterns of fractionation between P forms with respect to treatment. Overarchingly, biochar increased labile and moderately labile inorganic P and organic P by 30% to 70%, respectively, whilst compost had a relatively modest effect on these pools. Soil phosphatase activities at crop tillering increased following the FRR + Comp and FRR + BC treatments compared with those in RRR, except for acid phosphatase at Ben Tre. At harvest, there were no significant differences between the enzyme activities among the treatments. Rice yield was positively correlated with the more labile forms of P, soil C, and acid phosphatase activity. In the absence of organic amendments, there was no effect of triple versus double rice crops being grown in one-year cycle. Repeated application of biochar (10 Mg ha−1 × 5 times) showed potential to increase grain yields and total soil C in salt-affected acid soils, via modulation of P transformations to more plant-available forms. [ABSTRACT FROM AUTHOR]

Although various studies have investigated biochar (BC) soil amendments for improving soil microbial abundance, functions, and community structure, a comparison of dairy manure biochar (MBC) to wood biochar (WBC) is warranted given the large volume of manure produced in high-intensity dairy production. Additionally, the synergistic effects of different BC sources and loading percentages on microbial functions and community composition using massively parallel 16S DNA sequencing in BC-amended soils with different types of crops are limited. In this study, the synergistic effects of BC type, BC loading percentage, and crop types on soil fertility, prokaryote community diversity, and functions were investigated in a greenhouse study. The MBC and WBC were used to amend sandy loam soils at increasing BC loading percentages (0, 5, and 10%) to grow the cool-season forages crimson clover (Trifolium incarnatum; an annual legume) and Italian ryegrass (Lolium multiflorum Lam.; an annual forage grass) for 120 days. High nutrient concentrations in MBC shifted microbial communities towards r-strategists and alkaliphiles, potentially increasing the rate of nutrient bioremediation from high nitrogen- and phosphorus-containing soil amendments. This study enables emerging biochar agronomic use recommendations with different crops. [ABSTRACT FROM AUTHOR]

One strategy presented as an alternative to avoid using chemical substances in soil disinfestation consists in the technique of biosolarization. The aim of the present study was to analyze the effect of seasonality on the effectiveness of biosolarization with different organic amendments for the control of Fusarium oxysporum f. sp. lactucae (FOLAC) on lettuce plants, and to compare the results obtained using a classical soil infectivity bioassay and a qPCR-based molecular technique. None of the plants subjected to biosolarization in the summer season (469–700 and 0–463 h with temperature > 42 °C at 15 and 30 cm soil depth, respectively) showed damage by the pathogen except the untreated control. Conversely, in autumn (3–5 and 0–0 h at temperature = 38–40 °C at 15 and 30 cm soil depth, respectively), only two biosolarization treatments (wheat + semi-composted manure, sunflower pellets) that reduced FOLAC inoculum in soil and plants did not show any disease at the lowest depth (15 cm) in the soil infectivity bioassay. This same result was only obtained at 30 cm soil depth in the biosolarization treatment with sunflower pellets. The number of FOLAC sequences per gram of soil determined with qPCR was null in the biosolarization treatments in summer at both soil depths and corresponded to the absence of disease in the soil infectivity bioassay. A threshold of 145 sequences per gram of soil determined by the qPCR-based molecular technique corresponded to the presence of 10% of diseased lettuce plants infected by FOLAC. Therefore, this molecular technique has been shown to be useful for establishing the soil inoculum thresholds required for crop infection by pathogens, while reducing the time and execution tasks necessary to perform soil infectivity bioassays. [ABSTRACT FROM AUTHOR]

Prolonged drought periods, increasingly occurring worldwide due to global climate change, could affect the growth and productivity of both traditional and climate-resilient crops, including quinoa. Specifically, the vegetative growing cycle of this species is highly sensitive to drought conditions. In this context, using organic amendments could help plants cope with drought due to their ability to enhance soil water status. So, the current study aimed to investigate the effect of different organic amendments, i.e., two biochars (from woodchips and vineyard prunings) and a vermicompost (from cattle manure), applied to the soil alone and mixed at 2% rate (w/w), on the vegetative development of quinoa (cv. Titicaca), during which a period of water stress was imposed from the twelve-leaf stage to the bud stage. A set of growth-related parameters were measured both during and at the end of the experiment, along with a set of water-related parameters, at the end of the water-stress period and after soil re-watering. The results showed that woodchip biochar, both alone and mixed with vermicompost, significantly affected plant growth during the water-stress period, also allowing a quicker recovery once drought conditions ended. Indeed, the leaf number and area, SPAD index, leaf and stem fresh weight, and dry matter content in plants treated with woodchip biochar, alone and mixed with vermicompost, were higher than vineyard pruning biochar, alone and mixed with vermicompost and similar to the well-watered control plants. Similar results were observed considering the yield contributing traits detected at the end of the experiment, including the main panicle length, number of sub-panicle, as well as fresh weight and dry matter content of both panicle and sub-panicles. Additionally, the water-related parameters, especially the low turgid weight to dry weight ratio of woodchip biochar treated plants, showed evidence of better growth than vineyard pruning biochar. At the end of the experiment, the WUE of plants treated with woodchip biochar and vermicompost, both alone and mixed, was higher than vineyard pruning biochar alone and mixed with vermicompost. Among the tested organic amendments, woodchip biochar alone and mixed with vermicompost positively affected the vegetative growth response of quinoa under water-stress conditions. [ABSTRACT FROM AUTHOR]

Low soil fertility and low microbiological activity have been widely observed in certain newly cultivated lands. To develop effective agricultural management practices that can improve soil quality rapidly, a field experiment was conducted on paddy fields reclaimed from unused, low-slope, hilly wasteland in Quzhou City, Zhejiang Province, Southeast China. The six treatments that were applied included (1) control (CK), no crops were planted and no fertilizers were applied; (2) R, rice planted without fertilization; (3) RR, rice–ryegrass rotation without fertilizer application; (4) RRM, rice–ryegrass rotation with the application of mineral fertilizer; (5) RRMO, rice–ryegrass rotation with the application of mineral fertilizer and organic manure; and (6) RRMH, rice–ryegrass rotation with mineral fertilizer and humic acid application. The results showed that the application of fertilizer with ryegrass cropping improved the amounts of soil organic C (SOC) by 115–296% and particulate organic C (POC) by 162–256% (p < 0.05). Additionally, the RRMO treatment had the highest soil quality index value (0.81), which was significantly higher (p < 0.05) than that of the other treatments. The random forest model showed that N-related properties (including urease activity, total N, and particulate organic N), C-related properties (including SOC, POC, and cellulase activity), and available P could significantly (p < 0.05) explain the response of rice yield to different fertilization management strategies. Compared with CK, the cultivated land quality grades of RRMO and RRMH increased from Grade 9 to Grade 7. However, the RRMH obtained the highest net profit from farmland quota trading. Overall, RRMO and RRMH are suggested to rapidly improve soil productivity and maximize the economic benefit of newly cultivated land utilization, respectively. [ABSTRACT FROM AUTHOR]

Biochar is a potential amendment for the remediation of Cd-contaminated soils. Although the immobilization effect of biochar on soil Cd has been studied under indoor laboratory conditions, the effect of biochar on rice Cd uptake and soil Cd fractions under field conditions is still poorly understood. Here, the Cd content of the different organs of rice and the Cd fractions in soil were characterized for three years after the application of different amounts of biochar (0, 7.5, 15, 30 t ha−1, and 3 t ha−1 year−1). The Cd content of brown rice, husk, leaf, stem and sheath, and root under biochar treatment could be maximally reduced by up to 26.25%, 20.16%, 20.74%, 33.2%, and 26.89%, respectively. Biochar altered the Cd fractions in soil, including the decrease in exchangeable Cd content and the increase in Fe-Mn oxide bound Cd and organic bound Cd. The concentration factor of Cd uptake by rice was reduced by 32% under biochar application, while biochar had little influence on the transfer factor and distribution factor. The immobilization effect of biochar on soil Cd lasted for at least three years, but the trend of Cd immobilization efficiency over time for different amounts of biochar treatment was different. The Risk Assessment Code (RAC) of Cd in soil with biochar amendment could be reduced to a medium risk level from a high risk level. Redundancy analysis (RDA) revealed that changes in soil pH and Fe-Mn oxide bound Cd content caused by biochar application contributed most to the reduction in the Cd content of rice organs. These findings would enhance our understanding of the immobilization effect of biochar on Cd in paddy soil under field conditions. [ABSTRACT FROM AUTHOR]

The persistence of fluopyram and tebuconazole has been studied in different crops and agricultural soils. However, the behaviour of these fungicides may be altered when they are applied as a combined formulation in organically amended vineyard soils under field conditions. The purpose of this study is to evaluate the effect of applying spent mushroom substrate (SMS) or this residue re-composted with ophite (SMS + OF) on the adsorption, dissipation, and mobility of the fungicides fluopyram and tebuconazole in vineyard soils. Triplicate 10 m2 plots per treatment were set up in two different vineyard soils in the eastern La Rioja region: silt loam (ARN1) and sandy loam (ARN2), respectively, with low organic carbon (OC) content. The organic residues SMS and SMS + OF were applied at doses of 25 and 100 Mg ha−1. The adsorption distribution coefficients (Kd) increased when SMS and SMS + OF were applied, especially at the higher dose (100 Mg ha−1). The dissipation curve of both compounds fitted a two-phase kinetic model, with a very fast initial dissipation rate, followed by slower prolonged dissipation during the second phase. The dissipation half-lives (DT50) ranged between 4.7 and 26.3 days for fluopyram and between 2.3 and 6.3 days for tebuconazole in the different soils, increasing for fluopyram in the ARN1 amended with SMS and SMS + OF. The fungicide residues at 15–30 cm depth were lower in the unamended and amended sandy loam soil (ARN2), indicating that fungicides are dissipated mainly in the topsoil. The results indicate different dissipation mechanisms for both fungicides, as the adsorption by soil OC prevented the dissipation of fluopyram but facilitated the dissipation of tebuconazole, probably due to the formation of non-extractable residues. [ABSTRACT FROM AUTHOR]

Full-scale pyrolysis of faecal sludge in developing nations is an emerging technology for the complete removal of pathogens and the concurrent creation of biochar, a soil amendment shown to enhance crop productivity. Currently there is little information on the effects of faecal sludge biochar on soil and crop yield. Faecal sludge biochar was applied to an acidic, sandy soil to assess its effects on plant growth and yield in Micro-Tom, a model cultivar of tomato (Solanum lycopersicum L.). We examined four soil application treatments: a control soil, fertilizer treatment, biochar treatment, and a combined biochar and fertilizer treatment. The combined treatment of biochar and fertilizer together produced a tomato yield 2980% greater than the tomato yield from control soil, whereas biochar on its own increased the yield by 1060%. There was no significant difference in plant height between the combined biochar and fertilizer application and biochar on its own; however, both treatments significantly increased plant height compared to control soil. Below ground biomass showed a similar pattern, with no significant difference between biochar alone and combined biochar and fertilizer treatments, and both treatments resulted in significantly increased below ground biomass compared to control soil. The combined biochar and fertilizer treatment resulted in significantly lower water runoff than all other treatments. These findings have great potential implications for increasing food security and the creation of more sustainable agricultural practices, especially in developing regions. [ABSTRACT FROM AUTHOR]

Livestock farming produces high volumes of animal slurry that can be sanitized using low-cost treatments by pH adjustment, reducing pathogen contamination, and promoting slurry valorization as a safe fertilizer. This work aims to evaluate the impact of sandy soil amendment with dairy slurry treated by pH adjustment on the potential release of nutrients and coliforms into groundwater. A laboratory soil column leaching experiment was conducted and the surface application of six treatments was tested: raw dairy slurry, dairy slurry acidified with H2SO4, dairy slurry alkalinized with KOH, alkalinized/neutralized dairy slurry, mineral fertilizer, and a control. The fertilizer application rate was 0.08 g N kg−1 dry soil. Leachates were analyzed for pH, electrical conductivity, N-NH4+ and N-NO3−, macro- and micronutrients, and fecal coliforms. Results showed that amendment with dairy slurry led to significantly lower nitrate leaching potential than mineral fertilizer (maximum 16.1 vs. 50.4%). The use of hygienized slurry by alkalinization decreased the potential leaching of coliforms relative to raw slurry. However, incomplete sanitization by acidification strongly promoted coliform leaching and the risk of groundwater contamination. It can be concluded that the use of alkalinized dairy slurry is a safer solution than raw slurry with regard to the risk of groundwater pollution. [ABSTRACT FROM AUTHOR]

Rice cultivated in Cd-polluted acidic paddy soil poses important health risks in China. Decreasing Cd accumulation in rice is important for food safety and human health. Early rice cultivar ZY-819 and late rice cultivar XWX-13 with low Cd-accumulation potentials, and early rice cultivar LY-996 and late rice cultivar YZX with high Cd-accumulation potentials, were grown in mildly polluted double-cropping paddy fields (Cd content 0.3–0.6 mg kg−1). The effects of adding biochar (10 t ha−2), lime (1500 kg ha−2), and silicon–calcium fertilizer (SC; 2250 kg ha−2) and foliar spraying with silicon fertilizer solution (Si; 1500 g ha−2) on Cd uptake and transport in rice, were assessed in plot experiments. The soil amendments and foliar spraying decreased the Cd content of brown rice from the high Cd-accumulation potential cultivars. The soil amendments decreased the Cd content of LY-996 and YZX brown rice by 25.24–32.40% and 32.99–44.16%, respectively, and SC decreased the Cd content most. Foliar spraying with Si decreased the Cd content of LY-996 and YZC brown rice by 23.79% and 26.40%, respectively. When soil amendments and foliar spraying were combined, the Cd content of brown rice was decreased most by the SC–Si treatment. Compared with the control, the SC–Si treatment decreased the Cd content of LY-996, ZY-819, YZX, and XWX-13 brown rice by 45.63%, 35.67%, 52.79%, and 32.03%, respectively. Soil amendments can effectively decrease Cd uptake by rice roots and Cd migration from roots to shoots. Compared with the control, the soil amendments increased the soil pH and decreased Cd availability. The strongest effects were for the lime and SC treatments. Foliar spraying with Si can effectively decrease Cd translocation through stems and leaves to brown rice. Applying SC fertilizer and foliar spraying with Si is the best method for decreasing the Cd content of rice grown in mildly Cd-polluted paddy fields. [ABSTRACT FROM AUTHOR]

The proportion of acidic purple soils has increased. Consequently, an effective method for amelioration of acidic purple soils is urgently needed. A 40 day incubation experiment using apple tree biochar, fermented sheep manure and chicken manure was conducted to assess the effects of organic materials on the acidity and fertility of acidic purple soil. The results showed that application of organic materials increased soil pH and decreased soil-exchangeable acidity. All of the treatments increased soil-exchangeable and water-soluble base cations after incubation. Specifically, biochar increased soil pH and reduced exchangeable acidity more than the other two fermented manures, because biochar was rich in carbonates and other alkaline substances. The concentration of soil available K was significantly higher under biochar than manure addition, while the opposite was true for soil available P and N, with a higher increase in soil available P in the manure treatments. By evaluating the soil fertility using a fuzzy comprehensive method, it was found that the fermented livestock manure enhanced soil fertility more strongly than biochar. Considering the effectiveness of soil amendments and production cost, applying a large amount of fermented organic fertilizer is an effective approach to the amelioration of acidified purple soil. [ABSTRACT FROM AUTHOR]

The use of biochar and lime (CaO) is a common approach to mitigating soil acidification. However, little is known about how biochar and lime amendments impact N2O emissions and potential microbial mechanisms. We conducted a 45-day microcosm incubation experiment to examine N2O emission and associated functional guilds to biochar and lime amendment in an acidic tea plantation soil. Results show that lime and biochar treatments significantly reduced cumulative N2O emissions by 49.69% and 63.01%, respectively, while significantly increasing cumulative CO2 emissions by 27.51% and 19.35%, respectively. Additionally, lime and biochar treatments significantly decreased the abundances of bacterial nirK, nirS, nosZ and fungal nirK genes, while increasing that of the ammonia-oxidizing bacteria (AOB) and the complete ammonia-oxidizing bacteria (comammox) amoA genes. The stimulated or inhibitory effects of biochar on functional genes abundances were higher than lime. The N2O emission rate was positively linked with the abundance of the fungal nirK gene but was negatively correlated with AOB and comammox amoA genes abundances. The random forest and linear regression analysis revealed that fungal denitrifiers were the most important predictors of N2O emissions. Lime and biochar amendments reduced the alpha diversity and altered the community composition of nirK-harboring fungal denitrifiers. Ascomycota was the dominant fungal denitrifiers belonging to the families Nectriaceae, Aspergillaceae, and Chaetomiaceae, and the relative abundances of genera Chaetomium, Penicillium and Fusarium were positively correlated with N2O emissions. Overall, our findings suggest that biochar is more effective than lime in reducing N2O emissions, and this is likely due to the powerful effects it has on community traits of nirK-harboring fungal denitrifiers. [ABSTRACT FROM AUTHOR]

Soil salinization is a significant obstacle to agricultural development in arid and semiarid regions. While short-term experiments have demonstrated the effective improvement of saline soils through biochar amendment, the long-term efficacy in sustainably ameliorating such soils remains uncertain. Addressing this knowledge gap, this study investigated the long-term effects of biochar amendment in a field setting by applying different rates of biochar to a salt-affected soil and cultivating silage maize for three consecutive years. The comprehensive assessment includes not only maize growth but also changes in soil physical and chemical properties over the study period. The results reveal a notable elevation in maize above-ground dry matter, directly correlated to the enhanced uptake of nitrogen, phosphorous, and potassium. Additionally, biochar application improves saline soil physical properties, including reduced bulk density (1–23%), increased soil large pores (0.7–12%), and macroaggregates (24–141%), and chemical properties, including a decrease in exchangeable sodium percentage (35–48%), and an increase in soil total organic carbon (112–857%), total nitrogen (9–198%), available nitrogen (12–49%), phosphorus (141–538%) and potassium (57–895%). These improvements ultimately resulted in better maize growth. However, the amelioration effect of biochar on these soil properties gradually diminished over the three-year study. Consequently, this study suggests that biochar is a promising soil amendment that can enhance maize growth in saline soil for at least three years in a field experiment, providing valuable insights for sustainable agricultural practices in salt-affected regions. [ABSTRACT FROM AUTHOR]

The yield potential of switchgrass was verified by testing seven cultivars in a small-scale experiment carried out from 2018 to 2022 on Gleyic Fluvisol under Central European conditions. The treatments are as follows: pre-sowing (i/HA) soil humic preparation Humac AGRO (based on leonardite) with an ameliorative dose of 1000.0 kg ha−1 or (ii/NPK) basic nutrition with a dose of 220.0 kg ha−1 NPK; an annual dose of 70 kg ha−1 N was applied to both treatments (HA, NPK) and compared to (iii/UC) untreated control. A dry matter (DM) yield of 9.02 t ha−1 was achieved in the total average, which varied from 0.05 t ha−1 to 60.64 t ha−1. The yield was affected mainly by years (F-ratio 106.64), then by nutrition (F-ratio 79.03), followed by cultivars (F-ratio 56.87), and finally by replications (F-ratio 0.00). Switchgrass productivity increased according to the utility year; however, the driest year (2020—388 mm, 2021—372 mm, and 2022—288 mm) changed the order of the three full utility years (12.44, 19.13, and 7.73 t ha−1 DM, respectively). HA gives the highest DM yield of 13.69 t ha−1 on average with values of 9.19 and 4.19 for NPK and UC, respectively. The cultivars order was EG 1101 ˃ BO Master ˃ EG 1102 ˃ Kanlow ˃ Alamo ˃ Carthage ˃ NJ Ecotype (21.15, 12.48, 8.14, 7.70, 6.34, 4.47, and 2.89 t ha−1 DM when ranking average yield or 60.64, 45.20, 29.92, 29.15, 17.87, 9.86, and 5.93 t ha−1 DM when ranking maximal yields). [ABSTRACT FROM AUTHOR]

Today's agriculture has the challenge of ensuring food supply for a growing population while human activity has already deteriorated about 40% of the world's soils, reducing productive capacity and increasing reliance on mineral fertilizers. In this context, valorizing and recycling mineral and agricultural waste for use as substrates or soil supplements enhance a sustainable economy, as well as the development of activities focused on finishing the soil nutrients' cycle. Looking for an effective solution to the massive waste generation and to enhance the agronomic qualities of soils, this study investigates the agronomic impact of contrasting inorganic and organic materials such as green compost (GC), wood biochar (WB), rice husk ash (RA), and volcanic ash (VA) as amendments to an alkaline Luvisol under controlled conditions. In this sense, barley seeds were planted and grown in a greenhouse under controlled conditions for 60 days on a soil amended with the aforementioned materials. The amendments demonstrated appropriate attributes for improving soil agronomic properties, enhancing the soil's nutritional content with no effect on barley germination. The WB showed high aromaticity and abundance of refractory organic C. Both ash-rich amendments showed high P and K contents, which are important elements for plant development. The GC has high water retention capacity and an adequate C and N balance. Although the application of the amendments had no effect on barley yields, the plants from the ash-amended pots showed an increase of Photosystem II efficiency, indicative of a better physiological status. In terms of toxicological safety, the abundance of trace elements in soils and plants was investigated. All soils met the maximum allowable limits for these persistent pollutants. Nevertheless, longer-term tests on plants are required to determine the risk of Pb accumulation, particularly in soils amended with GC and compost-ash mixtures. The simultaneous combination of organic and inorganic amendments showed adequate agronomic attributes. WB analysis revealed its great recalcitrance and carbon sequestration potential. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) contamination is a global environmental challenge that threatens human food security. Lime combined with five different organic materials (rape seed cake, mushroom residue, straw, sawdust, and corn cobs) (LOM) at application ratios of 1:1 and lime sawdust combined with nitro-compound fertilizer (Ca(NO3)2·4H2O, KH2PO4, KNO3) (LSF) at different application rates were applied to Cd-contaminated soil. The present study investigates the effects of these organic–inorganic compound amendments on Cd bioavailability in soil, and Cd uptake and accumulation by edible Artemisia selengensis parts. A. selengensis was cultivated for three consecutive seasons in Cd-contaminated soil. LOM and LSF treatments obviously reduced the uptake and accumulation of Cd. Compared with the control soil, contents of Cd in edible parts of A. selengensis decreased by 19.26–33.33% and 26.67–32.78% in the first season, 18.60–32.79% and 18.37–32.79% in the second season, and 20.45–40.68% and 34.32–37.27% in the third season, respectively. The addition of Lime + Mushroom Residue and 70% Nitro-compound Fertilizer + Lime + Sawdust most significantly reduced Cd concentrations in the edible parts of the third A. selengensis season. LOM and LSF application increased soil pH and improved soil fertility, including available nitrogen, available phosphorus, available potassium, organic matter, and cation exchange capacity. Lime + Mushroom Residue improved plant yield the most. In addition, Lime + Mushroom Residue and 70% Nitro-compound Fertilizer + Lime + Sawdust had the lowest Cd accumulation and health risk indices, respectively. In conclusion, the Lime + Mushroom Residue and 70% Nitro-compound Fertilizer + Lime + Sawdust amendments significantly reduced health risks, enhanced A. selengensis growth, and promoted sustainable development of arable land under Cd-contaminated soil remediation. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) pollution poses a growing threat to rice production in acidic paddies. In south China, a common agricultural practice involves the combined utilization of Chinese milk vetch (M) and rice straw (R). However, it is unclear how the addition of lime to these amendments affects Cd bioavailability and accumulation in soil. Control (CK), chemical fertilizer (F), Chinese milk vetch + rice straw + chemical fertilizer (MRF), and Chinese milk vetch + rice straw + chemical fertilizer + lime (MRFL) treatments were applied to develop a kind of green, efficient, and practical amendment for acidic paddies. We conducted a microplot experiment to explore Cd immobilization in paddy soil and the Cd content in rice grains with these treatments. The results showed that compared with F, the rice Cd in the MRF and MRFL treatments were significantly decreased by 51.7% and 65.2% in early rice and 23.0% and 43.3% in late rice, respectively. Both the MRF and MRFL treatments significantly reduced soil available Cd and weak acid-extractable cadmium (Aci-Cd) concentrations and increased soil organic matter (SOM), exchangeable cation concentrations, and pH, which converted Cd into a stable form in soil. In addition, the MRF and MRFL treatments increased soil pH value by reducing soil exchangeable hydrogen ion concentration (E-H). Additionally, recombination of Cd forms was the primary factor in the reduction in available Cd concentration according to partial least squares path modeling (PLS-PM) analysis. The Cd concentration of rice grains was primarily associated with soil available Cd, soil pH value, and SOM. Overall, these results provide useful data and novel insights into reducing rice grain Cd in south China. [ABSTRACT FROM AUTHOR]

Legumes have a high demand for phosphorus (P) but also have effective physiological and morphological strategies of P mobilisation. In order to evaluate the inter- and intraspecific P efficiency of small-grain legumes under contrasting long-term P management, eight accessions each of alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) were cultivated in two consecutive growing periods from 2020 to 2021 in a field trial established in 1998. Six treatments (no P, triple-superphosphate (TSP), biomass ash, cattle manure, biowaste compost, and biowaste compost + TSP) were considered as P sources. While the yield clearly varied between both growing seasons, the differences between alfalfa and red clover were relatively small (4.7 vs. 4.9 Mg ha−1 in 2020 and 12.0 vs. 10.5 Mg ha−1 in 2021, p < 0.05). Even after more than 20 years of P management, crop yields were hardly affected by mineral P sources (TSP and biomass ash) while organic fertilisers increased the yields and nutrient uptake of plants and also raised soil P pools and the activities of soil enzymes in comparison to the control. A relevant crop effect was only found for the nitrogen (N) leaching with higher mineral N contents in 60 to 90 cm soil depth measured for red clover compared to alfalfa (11.8 vs. 4.8 kg ha−1, p < 0.05). Our results emphasise the high P efficiency of small-grain legumes without pronounced inter- or intraspecific differences. The yield-enhancing effect of organic amendments was related to higher soil fertility rather than to P supply. [ABSTRACT FROM AUTHOR]

The input of exogenous organic materials is an effective way to improve soil organic matter (SOM) content in cropland. The exploration of the impact of new organic materials such as woody peat on black soil fertility can provide an important reference for preventing the degradation of black soil in Northeast China. In this study, the effects of adding woody peat to SOM and the soil-integrated fertility of black cropland were studied by seven treatments (no organic matter addition, CK; crop straw returning, SR; decomposed straw addition, DS; organic manure addition, OM; 6 t/ha woody peat addition, LWP; 10.5 t/ha natural humus material addition, MWP; and 15 t/ha natural humus material addition, HWP). The results show that natural humus material additions (LWP, MWP, and HWP treatments) could significantly increase SOM (increased by 4.79~9.41 g/kg), labile SOM (increased by 2.49~4.52 g/kg), and recalcitrant SOM (increased by 2.13~6.39 g/kg) components, respectively. For comparison, traditional organic material inputs (SR, DS, and OM treatments) had no significant effect on SOM but induced an increase in the labile SOM component in the following year. This study also found that natural humus material additions could improve soil-integrated fertility in a year term, especially in promoting SOM accumulation. However, organic manure amendment showed both the advantage of increasing soil fertility slightly and the disadvantage of increasing soil salt sharply. In conclusion, compared with traditional exogenous organic materials, the natural humus material amendment technique can rapidly increase the total SOM quantity and its different stability components and has a great effect in improving the integrated fertility of black soil. Thus, it is of significance to further study the potential of natural humus material amendment in the fertility of black soil in future. [ABSTRACT FROM AUTHOR]

Some biochars produced by pyrolysis of biomass have the potential to sequester C and enhance nutrient supplies in agricultural soils. A 28-day lab incubation was used to assess the potential effects of biochars derived from pine chips (PC) or poultry litter (PL) applied at five application rates (0, 22.5, 45.0, 67.5, and 90 Mg ha−1 equivalent). Biochars were applied to two acidic Ultisols, a Cecil sandy loam and a Tifton loamy sand, found in Georgia, USA. Cumulative basal soil respiration was measured over the 28-day incubation. Other soil properties measured before and after incubation were soil pH, total soil organic carbon (SOC), total soil N, soluble organic C (OC), soil mineral nitrogen (NH4+-N and NO3−-N), and microbial biomass C (MBC). Before incubation, addition of both PC and PL biochars increased soil pH, total SOC, and C:N ratio in both soils. Addition of the PL biochar increased total soil N, soluble OC, and NO3−-N in both soils, MBC in Tifton soil, and NH4+-N in Cecil soil. Addition of the PC biochar decreased NO3−-N in Cecil soil but increased it in Tifton soil. After the 28-day incubation, averaged across soils, pH increased in the 22.5 Mg ha−1 PC and 22.5 and 67.5 Mg ha−1 PL treatments, total SOC declined in the 45 and 67.5 Mg ha−1 PC treatments, and the C:N increased in soil controls and decreased in the 67.5 Mg ha−1 PC treatment. In Cecil soil, the MBC declined in PL treatments except at 90 Mg ha−1, and NH4+-N declined in the 90 Mg ha−1 PC treatments. In Tifton soil, MBC increased in the 45 Mg ha−1 PL treatment, and NH4+-N increased in all but the 22.5 Mg ha−1 PL treatments. Total N and NO3−-N did not change with incubation. Basal respiration was not affected by biochar, thought it was generally greater in Cecil than Tifton soil. Net SOC loss and the initial increase in soluble OC and MBC indicated potential C priming from adding both biochars. Increased NH4+-N with time in Tifton PL treatments indicated potential N priming. In Cecil soil, the PC biochar may have immobilized NH4+-N, but PL biochar likely supplied it. In Tifton soil, PC biochar appeared to be generally inert, but PL biochar supplied soluble OC and NH4+-N, although it might have inhibited nitrification. [ABSTRACT FROM AUTHOR]

High-temperature and high-light are the main adversity stresses faced by strawberry seedlings and open-field cultivation in summer. Chitosan (CTS) is widely used in agriculture as a soil amendment, plant growth regulator, and promoter of cold resistance. However, the effects of CTS on strawberry seedlings under the combined stress of high-temperature and high-light are unclear. This study aimed to determine the effect of CTS on strawberry seedlings under the combined stress of high-temperature and high-light. In this study, Xuelixiang strawberry was used as the experimental plant material. The leaves were sprayed with 100 mg/Kg CTS or deionized aqueous solution and placed under high-temperature and high-light (38 °C, 1800 μ mol·m−2·s−1, respectively) for 8 h. In addition, a suitable temperature and light (23 °C, 400 μ mol·m−2·s−1, respectively) was sprayed with deionized water as a control. The results showed that compared with non-CTS treatment, the chlorophyll (Chl) content in strawberry plants increased by 16.9% after CTS treatment; the net CO2 exchange (Pn) increased by 74.9%; and the maximum photochemical efficiency increased by 20.1%. In addition, CTS treatment increased the content of antioxidants; increased osmotic adjustment substances; improved the activity of reduced glutathione with reduced ascorbic acid (AsA-GSH) circulating antioxidant enzymes; removed reactive oxygen species in plants in time; and reduced the damage of reactive oxygen species to photosynthetic organs and cell membranes, thereby reducing high-temperature and high-light injury to strawberry seedlings. This study shows that CTS can improve the negative effects of high-temperature and high-light stress on strawberry seedlings. [ABSTRACT FROM AUTHOR]

Soil acidity is a crop production problem of increasing concern in acid red soil. The potential of biochar as a soil amendment/for soil acid management in agricultural fields is a recently recognized yet underutilized technology. Related evidence is currently limited to short-term indoor experiments with one-time BC applications and no crop cultivation, yet the degree to which soil acidity may be impacted by the biochar aging process on long-time scale remains unclear. To evaluate the effects of successive seasonal applications of rice straw-derived biochar (BC) on acidity and fertility of soil, a five-year outdoor column trial was conducted using wheat-millet rotated acidic upland soils from the south of China. BC was applied to the top 0–15 cm of soil at the rates of 0 (BC0), 2.25 (BCL), and 22.5 (BCM) Mg ha−1 with an identical dose of NPK fertilizers at the beginning of each crop season. Our results showed that the wheat-millet biomass yield gradually decreased over five rotation cycles in BC0 without BC application. In contrast, after five rotations, BCM led to an increase in the total wheat/millet grain yield by 138%, and the straw yield increased by 253% compared to the control. The cumulative above-ground nutrient uptake of P, K, Ca, Na, and Mg in BCM also increased by 139%, 171%, 129%, 182%, and 71%, respectively, compared to that in the control. This positive effect was attributed to the increase in soil pH (3.29 units), cation exchange capacity (5.66 cmol kg−1), soil available P (241%), K (513%), Ca (245%), Mg (265%), exchange base (3.36 cmol kg−1), base saturation percentage (65.7%), and decrease in the exchangeable acidity, especially exchangeable Al3+ content (<0.1 cmol kg−1). Our results demonstrated that rice straw-derived BC application to soil at 22.5 t ha−1 was found to be highly consistent in decreasing soil acidity and reducing soluble and exchangeable Al3+, indicating its higher ameliorating capacity in the south of China in the long run. [ABSTRACT FROM AUTHOR]

The use of biochar as a soil amendment has substantial potential to enhance soil quality and carbon sequestration. However, the responses to the addition of biochar based on soil microbial residues are not well understood, particularly at the aggregate level. Herein, a two-year field experiment investigated the characteristics of distribution of microbial residues in calcareous fluvo-aquic soil aggregates (SA) in Henan Province, China. Four treatments were established as follows: no fertilizer (CK), chemical fertilizer (NPK), biochar (BC), and biochar combined with chemical fertilizer (NPK + BC). The results showed that the effects of particle size substantially impacted the microbial residues with 2–0.25 mm SA having the largest contents of amino sugars and microbial residual carbon (MRC), followed by >2 mm SA. Compared with the CK, the NPK treatment markedly enhanced the levels of glucosamine (GluN), galactosamine (GalN), muramic acid (MurA), total amino sugar (TAS), and MRC in the 2–0.25 mm SA by 26.69%, 24.0%, 23.62%, 25.11%, and 24.82%, respectively. The NPK + BC treatment significantly increased the contents of GluN, GalN, TAS, and MRC in the bulk soil and 0.25–0.053 mm SA compared with the NPK treatment. Bacterial biomass and the activity of N-acetyl-glucosaminidase in the bulk soil and SA markedly and positively affected the content of carbon in the amino sugars and microbial residues. Overall, the 2–0.25 mm SA were microenvironments with the largest accumulation of soil microbial residues, and the combined application of NPK + BC was more effective at increasing the accumulation of microbial residues in the SA, which provides an ideal fertilization strategy to improve the soil microenvironment and enhance soil quality. [ABSTRACT FROM AUTHOR]