A comprehensive review on enhancing nutrient use efficiency and productivity of broadacre (arable) crops with the combined utilization of compost and fertilizers

The synergistic effects of organic composts and microelements co-application in enhancing potato productivity in saline soils

Soil salinity is a major threat hindering the optimum growth, yield, and nutritional value of potato. The application of organic composts and micronutrients can effectively ameliorate the salinity-deleterious effects on potato growth and productivity. Herein, the combined effect of banana and soybean composts (BCo and SCo) application alongside foliar supplementation of boron (B), selenium (Se), cobalt (Co), and titanium (Ti) were investigated for improving growth, physiology, and agronomical attributes of potato plants grown in saline alluvial soil. Salinity stress significantly reduced biomass accumulation, chlorophyll content, NPK concentrations, yield attributes, and tuber quality, while inducing malondialdehyde and antioxidant enzymes. Co-application of either BCo or SCo with trace elements markedly alleviated salinity-adverse effects on potato growth and productivity. These promotive effects were also associated with a significant reduction in malondialdehyde content and activities of peroxidase and superoxide dismutase enzymes. The co-application of BCo and B/Se was the most effective among other treatments. Principle component analysis and heatmap also highlighted the efficacy of the co-application of organic composts and micronutrients in improving the salinity tolerance of potato plants. In essence, the co-application of BCo with B and Se can be adopted as a promising strategy for enhancing the productivity of potato crops in salt-affected soils.

Short-term high-temperature pretreated compost increases its application value by altering key bacteria phenotypes

Short-term high-temperature pretreatment can effectively shorten the maturity period of organic waste composting and improve the fertilizer efficiency and humification degree of products. To investigate the effect and mechanism of the end products on the saline-alkali soil improvement and plant growth, the short-term high-temperature pretreatment composting (SHC) and traditional composting (STC) were separately blended with saline-alkali soil in a ratio of 0-40 % to establish a soil-fertilizer blended matrix for cultivating Lolium perenne L. The pot experiments combined with principal component analysis showed Lolium perenne L. planted in 20 % SHC-blended saline-alkali soil had the best growth effect, and its biomass, chlorophyll content, and plant height were 109-113 % higher than STC. The soil physicochemical property analysis showed that SHC and STC increased the soil nutrient content, humification degree, and enzyme activity at any blending ratio. The microbial analysis showed that 20 % SHC in the saline-alkali soil stimulated the growth of functional microorganisms and the addition of SHC promoted the sulfur cycle, nitrogen fixation, and carbon metabolism in the soil-plant system. The correlation analysis showed that pH; nutrient contents; and urease, catalase, sucrase, and phosphatase activities in the saline-alkali soil were significantly correlated with plant growth indexes (p < 0.05). Georgenia and norank_f__Fodinicurvataceae had a stronger correlation with four types of enzyme activities (p < 0.01). SHC improved the saline-alkali soil and promoted plant growth by adjusting soil pH, increasing soil nutrients, and influencing soil enzyme activity and dominant flora. This study provides a theoretical basis for applying SHC products in soil improvement.

Combined Application of Leguminous Green Manure and Straw Determined Grain Yield and Nutrient Use Efficiency in Wheat-Maize-Sunflower Rotations System in Northwest China

Leguminous green manure (LGM) has a reputation for improving crop productivity. However, little is known about the beneficial interactions with straw on crop yield and nutrient (N, P, K) use efficiency. Herein, a 9-year field experiment (from 2015 to 2023) containing three treatments-(1) chemical fertilizer as the control (CK), (2) NPK + straw return (Straw) and (3) NPK + straw return with LGM (Straw + LGM)-was conducted to investigate whether the combined application of LGM and straw can increase productivity and nutrient use efficiency in the wheat-maize-sunflower diversified cropping rotation. The results showed that in the third rotation (2021-2023), Straw + LGM significantly increased wheat yield by 10.2% and maize yield by 19.9% compared to CK. The total equivalent yield under Straw + LGM was the highest (26.09 Mg ha-1), exceeding Straw and CK treatments by 2.7% and 12.3%, respectively. For each 2 Mg ha-1 increase in straw returned to the field, sunflower yield increased by 0.2 Mg ha-1, whereas for each 1 Mg ha-1 increase in LGM yield from the previous crop, sunflower yield increased by 0.45 Mg ha-1. Compared to CK, the co-application of LGM and straw increased the N use efficiency of maize in the first and third rotation cycle by 70.6% and 55.8%, respectively, and the P use efficiency by 147.8% in the third rotation cycle. Moreover, Straw treatment led to an increase of net income from wheat and sunflower by 14.5% and 44.6%, while Straw + LGM increased the net income from maize by 15.8% in the third rotation cycle. Combining leguminous green manure with a diversified cropping rotation has greater potential to improve nutrient use efficiency, crop productivity and net income, which can be recommended as a sustainable agronomic practice in the Hetao District, Northwest China.

A review of the influence of heat drying, alkaline treatment, and composting on biosolids characteristics and their impacts on nitrogen dynamics in biosolids-amended soils

Application of biosolids to agricultural land has gained increasing attention due to their rich nutrient content. There are a variety of treatment processes for converting sewage sludge to biosolids. Different treatment processes can change the physicochemical properties of the raw sewage sludge and affect the dynamics of nutrient release in biosolids-amended soils. This paper reviews heat drying, alkaline treatment, and composting as biosolids treatment processes and discusses the effects of these treatments on biosolid nitrogen (N) content and availability. Most N in the biosolids remain in organic forms, regardless of biosolids treatment type but considerable variation exists in the mean values of total N and mineralizable N across different types of biosolids. The highest mean total N content was recorded in heat-dried biosolids (HDB) (4.92%), followed by composted biosolids (CB) (2.25%) and alkaline-treated biosolids (ATB) (2.14%). The mean mineralizable N value was similar between HDB and ATB, with a broader range of mineralizable N in ATB. The lowest N availability was observed in CB. Although many models have been extensively studied for predicting potential N mineralization in soils amended with organic amendments, limited research has attempted to model soil N mineralization following biosolids application. With biosolids being a popular, economical, and eco-friendly alternative to chemical N-fertilizers, understanding biosolids treatment effects on biosolids properties is important for developing a sound biosolids management system. Moreover, modeling N mineralization in biosolids-amended soils is essential for the adoption of sustainable farming practices that maximize the agronomic value of all types of biosolids.

Biochar modulating soil biological health: A review

Biochar can be used for multifunctional applications including the improvement of soil health and carbon storage, remediation of contaminated soil and water resources, mitigation of greenhouse gas emissions and odorous compounds, and feed supplementation to improve animal health. A healthy soil preserves microbial biodiversity that is effective in supressing plant pathogens and pests, recycling nutrients for plant growth, promoting positive symbiotic associations with plant roots, improving soil structure to supply water and nutrients, and ultimately enhancing soil productivity and plant growth. As a soil amendment, biochar assures soil biological health through different processes. First, biochar supports habitats for microorganisms due to its porous nature and by promoting the formation of stable soil micro-aggregates. Biochar also serves as a carbon and nutrient source. Biochar alters soil physical and chemical properties, creating optimum soil conditions for microbial diversity. Biochar can also immobilize soil pollutants and reduce their bioavailability that would otherwise inhibit microbial growth. However, depending on the pyrolysis settings and feedstock resources, biochar can be comprised of contaminants including polycyclic aromatic hydrocarbons and potentially toxic elements that can inhibit microbial activity, thereby impacting soil health.

Nitrogen dynamics and biological processes in soil amended with microalgae grown in abattoir digestate to recover nutrients

The use of microalgae for nutrient recovery from wastewater and subsequent conversion of the harvested biomass into fertilizers offers a sustainable approach towards creating a circular economy. Nonetheless, the process of drying the harvested microalgae represents an additional cost, and its impact on soil nutrient cycling compared to wet algal biomass is not thoroughly understood. To investigate this, a 56-day soil incubation experiment was conducted to compare the effects of wet and dried Scenedesmus sp. microalgae on soil chemistry, microbial biomass, CO2 respiration, and bacterial community diversity. The experiment also included control treatments with glucose, glucose + ammonium nitrate, and no fertilizer addition. The Illumina Mi-Seq platform was used to profile the bacterial community and in-silico analysis was performed to assess the functional genes involved in N and C cycling processes. The maximum CO2 respiration and microbial biomass carbon (MBC) concentration of dried microalgae treatment were 17% and 38% higher than those of paste microalgae treatment, respectively. NH4+ and NO3- released slowly and through decomposition of microalgae by soil microorganisms as compared to synthetic fertilizer control. The results indicate that heterotrophic nitrification may contribute to nitrate production for both microalgae amendments, as evidenced by low amoA gene abundance and a decrease in ammonium with an increase in nitrate concentration. Additionally, dissimilatory nitrate reduction to ammonium (DNRA) may be contributing to ammonium production in the wet microalgae amendment, as indicated by an increase in nrfA gene and ammonium concentration. This is a significant finding because DNRA leads to N retention in agricultural soils instead of N loss via nitrification and denitrification. Thus, further processing the microalgae through drying or dewetting may not be favorable for fertilizer production as the wet microalgae appeared to promote DNRA and N retention.

Fertilization of Microbial Composts: A Technology for Improving Stress Resilience in Plants

Microbial compost plays a crucial role in improving soil health, soil fertility, and plant biomass. These biofertilizers, based on microorganisms, offer numerous benefits such as enhanced nutrient acquisition (N, P, and K), production of hydrogen cyanide (HCN), and control of pathogens through induced systematic resistance. Additionally, they promote the production of phytohormones, siderophore, vitamins, protective enzymes, and antibiotics, further contributing to soil sustainability and optimal agricultural productivity. The escalating generation of organic waste from farm operations poses significant threats to the environment and soil fertility. Simultaneously, the excessive utilization of chemical fertilizers to achieve high crop yields results in detrimental impacts on soil structure and fertility. To address these challenges, a sustainable agriculture system that ensures enhanced soil fertility and minimal ecological impact is imperative. Microbial composts, developed by incorporating characterized plant-growth-promoting bacteria or fungal strains into compost derived from agricultural waste, offer a promising solution. These biofertilizers, with selected microbial strains capable of thriving in compost, offer an eco-friendly, cost-effective, and sustainable alternative for agricultural practices. In this review article, we explore the potential of microbial composts as a viable strategy for improving plant growth and environmental safety. By harnessing the benefits of microorganisms in compost, we can pave the way for sustainable agriculture and foster a healthier relationship between soil, plants, and the environment.

From waste to wealth: Innovations in organic solid waste composting

Organic solid waste (OSW) is not only a major source of environmental contamination, but also a vast store of useful materials due to its high concentration of biodegradable components that can be recycled. Composting has been proposed as an effective strategy for recycling OSW back into the soil in light of the necessity of a sustainable and circular economy. In addition, unconventional composting methods such as membrane-covered aerobic composting and vermicomposting have been reported more effective than traditional composting in improving soil biodiversity and promoting plant growth. This review investigates the current advancements and potential trends of using widely available OSW to produce fertilizers. At the same time, this review highlights the crucial role of additives such as microbial agents and biochar in the control of harmful substances in composting. Composting of OSW should include a complete strategy and a methodical way of thinking that can allow product development and decision optimization through interdisciplinary integration and data-driven methodologies. Future research will likely concentrate on the potential in controlling emerging pollutants, evolution of microbial communities, biochemical composition conversion, and the micro properties of different gases and membranes. Additionally, screening of functional bacteria with stable performance and exploration of advanced analytical methods for compost products are important for understanding the intrinsic mechanisms of pollutant degradation.

Release and mobility characteristics of thallium from polluted farmland in varying fertilization: Role of cation exchange

Batch and column leaching tests were used to study thallium's release and migration behaviour and evaluate its potential toxicity risks in soil. The results indicated that leaching concentrations of Tl using TCLP and SWLP were much higher than the threshold, indicating a high risk of thallium pollution in the soil. Furthermore, the intermittent leaching rate of Tl by Ca²⁺ and HCl reached its maximum value, demonstrating the easy release of Tl. After HCl leaching, the form of Tl in the soil has changed, and ammonium sulfate has increased its extractability. Additionally, the extensive application of calcium promoted the release of Tl, increasing its potential ecological risk. Spectral analysis showed that Tl was mainly present in minerals such as Kaolinite and Jarosite, and exhibited significant adsorption capacity for Tl. HCl and Ca²⁺ damaged the crystal structure of the soil, greatly enhancing the migration and mobility of Tl in the environment. More importantly, XPS analysis confirmed that the release of Tl (I) in the soil was the leading cause of increased mobility and bioavailability. Therefore, the results revealed the risk of Tl release in the soil, providing theoretical guidance for its pollution prevention and control.

Tofu by-product soy whey substitutes urea: Reduced ammonia volatilization, enhanced soil fertility and improved fruit quality in cherry tomato production

Soy whey is an abundant, nutrient-rich and safe wastewater produced in tofu processing, so it is necessary to valorize it instead of discarding it as sewage. Whether soy whey can be used as a fertilizer substitute for agricultural production is unclear. In this study, the effects of soy whey serving as a nitrogen source to substitute urea on soil NH₃ volatilization, dissolved organic matter (DOM) components and cherry tomato qualities were investigated by soil column experiment. Results showed that the soil NH₄⁺-N concentrations and pH values of the 50% soy whey fertilizer combined with 50% urea (50%-SW) and 100% soy whey fertilizer (100%-SW) treatments were lower than those of 100% urea treatment (CKU). Compared with CKU, 50%-SW and 100%-SW treatments increased the abundance of ammonia oxidizing bacteria (AOB) by 6.52-100.89%, protease activity by 66.22-83.78%, the contents of total organic carbon (TOC) by 16.97-35.64%, humification index (HIX) of soil DOM by 13.57-17.99%, and average weight per fruit of cherry tomato by 13.46-18.56%, respectively. Moreover, soy whey as liquid organic fertilizer reduced the soil NH₃ volatilization by 18.65-25.27% and the fertilization cost by 25.94-51.87% compared with CKU. This study provides a promising option with economic and environmental benefits for soy whey utilization and cherry tomato production, which contributes to the win-win effectiveness of sustainable production for both the soy products industry and agriculture.

Soil organic carbon stability mediate soil phosphorus in greenhouse vegetable soil by shifting phoD-harboring bacterial communities and keystone taxa

Addition of organic amendments, such as manure and straw, to arable fields as a partial substitute for mineral phosphorus (P), are a sustainable practice in high-efficiency agricultural production. Different organic inputs may induce varied soil organic carbon (OC) stability and phoD harboring microbes, subsequently regulate P behavior, but the underlying mechanisms are poorly understood. A 11-year field experiment examined P forms by ³¹P-nuclear magnetic resonance (NMR), OC chemical composition by ¹³C NMR, and biologically-based P availability methods, phoD bacterial communities, and their co-occurrence in soils amended with chemical P fertilizer (CF), chemical P partly substituted by organic amendments including pig manure (CM), a mixture of pig manure and corn straw (CMS), and corn straw (CS), with equal P input in all treatments. Organic amendments significantly increased soil labile P_i (CaCl₂-P, citrate-P, 2.91-3.26 and 1.16-1.32 times higher than CF) and P_o (enzyme-P, diesters, 4.08-7.47 and 1.71-2.14 times higher than CF) contents and phosphatase activities, while significantly decreased aromaticity (AI) and recalcitrance indexes (RI) of soil C, compared with CF. The keystone genera in manured soils (Alienimomas and Streptomyces) and straw-applied soils (Janthinobacterium and Caulobacter) were significantly correlated with soil enzyme-P, microbial biomass P (MBP), diesters, and citrate-P. Soil AI and RI were significantly correlated with the phoD keystone and soil P species. It suggested that the keystone was impacted by soil OC stability and play a role in regulating P redistribution in amended soils. This study highlights how manure and straw incorporation altered soil OC stability, shaped the phoD harboring community, and enhanced soil P biological processes promoted by the keystone taxa. The partial substitution of mineral P by mixture of manure and straw is effectively promote soil P availability and beneficial for environmental sustainability.

Contaminant containment for sustainable remediation of persistent contaminants in soil and groundwater

Contaminant containment measures are often necessary to prevent or minimize offsite movement of contaminated materials for disposal or other purposes when they can be buried or left in place due to extensive subsurface contamination. These measures can include physical, chemical, and biological technologies such as impermeable and permeable barriers, stabilization and solidification, and phytostabilization. Contaminant containment is advantageous because it can stop contaminant plumes from migrating further and allow for pollutant reduction at sites where the source is inaccessible or cannot be removed. Moreover, unlike other options, contaminant containment measures do not require the excavation of contaminated substrates. However, contaminant containment measures require regular inspections to monitor for contaminant mobilization and migration. This review critically evaluates the sources of persistent contaminants, the different approaches to contaminant remediation, and the various physical-chemical-biological processes of contaminant containment. Additionally, the review provides case studies of contaminant containment operations under real or simulated field conditions. In summary, contaminant containment measures are essential for preventing further contamination and reducing risks to public health and the environment. While periodic monitoring is necessary, the benefits of contaminant containment make it a valuable remediation option when other methods are not feasible.

Biochar-compost as a new option for soil improvement: Application in various problem soils

Due to the synergistic effects of biochar and compost/composting, the combined application of biochar and compost (biochar-compost) has been recognized as a highly promising and efficient method of soil improvement. However, the willingness to apply biochar-compost for soil improvement is still low compared to the use of biochar or compost alone. This paper collects data on the application of biochar-compost in several problem soils that are well-known and extensively investigated by agronomists and scientists, and summarizes the effects of biochar-compost application in common problem soils. These typical problem soils are classified based on three different characteristics: climatic zones, abiotic stresses, and contaminants. The improvement effect of biochar-compost in different soils is assessed and directions for further research and suggestions for application are made. Generally, biochar-compost mitigates the high mineralization rate of soil organic matter, phosphorus deficiency and aluminum toxicity, and significantly improves crop yields in most tropical soils. Biochar-compost can help to achieve long-term sustainable management of temperate agricultural soils by sequestering carbon and improving soil physicochemical properties. Biochar-compost has shown positive performance in the remediation of both dry and saline soils by reducing the threat of soil water scarcity or high salinity and improving the consequent deterioration of soil conditions. By combining different mechanisms of biochar and compost to immobilize or remove contaminants, biochar-compost tends to perform better than biochar or compost alone in soils contaminated with heavy metals (HMs) or organic pollutants (OPs). This review aims to improve the practicality and acceptability of biochar-compost and to promote its application in soil. Additionally, the prospects, challenges and future directions for the application of biochar-compost in problem soil improvement were foreseen.

Can Agricultural Socialized Services Promote the Reduction in Chemical Fertilizer? Analysis Based on the Moderating Effect of Farm Size

On the basis of the data of 855 farmer households in the 2020 China Land Economic Survey, this paper uses an extended regression model to empirically study the impact of agricultural socialized services on the reduction in chemical fertilizer and the moderating effect of farm size in the above impact path. The results show that adoption of agricultural socialized services by farmers can significantly promote reduction in chemical fertilizer. The moderating effect test shows that the farm size is instrumental in strengthening the effect of promoting agricultural socialized services on the reduction in chemical fertilizer. The effect of technology-intensive services on fertilizer reduction was more pronounced than that of labor-intensive services. Agricultural socialized services have a greater effect on the reduction in chemical fertilizer for farmers with a higher degree of part-time employment, but farm size can significantly enhance the fertilizer reduction effect generated by the adoption of agricultural socialized services by farmers with a lower degree of part-time employment. Therefore, we recommend further developing agricultural socialized services, strengthening the supply of agricultural green production services, and playing the role of agricultural socialized services in chemical fertilizer reduction. We also posit that encouraging large-scale farmers to adopt agricultural socialized services would further promote fertilizer reduction.