Rice Straw Compost Research Articles

Comparative Environmental and Economic Analysis of Biomethane Production from Co-Digestion of Rice Straw and Spent Mushroom Compost: Application of Zero-Valent Iron Nanoparticles

Abstract Spent mushroom compost is one of the main potentials for biogas production. In recent years, several studies employed adding nanoparticles and alkaline pretreatment for improving biogas production. The present study is one of the pioneer studies that employ hybrid alkaline pretreatment (0, 5, and 15 mg of NaOH) and zero-valent iron nanoparticles (0, 10, 20, 30, and 40 mg) for improving the co-digestion of spent mushroom compost and rice straw. According to the results, retention time (RT) and nanoparticle (NP) concentrations have the most significant impact on biomethane production (significant at 1% probability level), while the NaOH concentration has the lowest impact on biomethane production (significant at 5% probability level) in comparison with RT and NP concentration. Also, the maximum biomethane production is related to NP40Na15 (about 200% higher than the control). The minimum cumulative biomethane production is related to NP0Na15 (about 30% lower than the control). The lowest relative environmental midpoint impact is related to NP40Na15, which was on average about 60% lower than the control. Adding NPs at high concentrations of NaOH reduces the midpoint impacts. The results of the study could lead to new, ecologically friendly biomethane production methods that make better use of agricultural and organic wastes.

Fusing Genotype and Soil Organic/Inorganic Amendment to Improve Saline-sodic Properties and Rice Productivity

Soil salinization and sodification have become a considerable threat to sustainable crop production for food security. The efficient biological practice in rice cropping systems, besides modulating saline-sodic soil properties using different amendments, is a necessary tactic to accelerate reclamation. This research aimed to evaluate the potential ameliorative effect of seven organic/inorganic amendments addition on soil properties and the differential responses of three rice genotypes under saline-sodic soil conditions at north of Egypt. A 2-year (2019 and 2020) field experiment was conducted with three rice genotypes, viz., Sakha 106, Giza 179, and Egyptian hybrid rice 1 (EHR1) cultivated in saline-sodic-affected soil amended with seven organic/inorganic amendments, i.e., gypsum, rice straw compost (RSC), farmyard manure (FYM), sulfur, sulfuric acid, calcium superphosphate, and rice husk beside control (unamended soil). This experimental design was a two-factor strip plot with randomized complete blocks with four replications. The morpho-physiological (SPADchlorophyll, water content, leaf area index, and shoot dry weight) and biochemical (catalase (CAT) activity, proline content, carbohydrates, leaf sodium (Na+) and potassium (K+), and Na+/K+ ratio) responses, the associated soil physico-chemical and microbial properties, yield, and its components were determined. RSC, gypsum, or sulfur were the most effective amendments in ameliorating saline-sodic soil properties by significantly reducing electrical conductivity, bulk density, and pH compared to the control and initial soil. Gypsum, RSC, FYM, or sulfur amendments significantly decreased the soil Na+ by 14.2, 11.7, 9.1, and 8.3%; sodium adsorption ratio by 14.9, 12.6, 10.4, and 8.7%; and exchangeable sodium percentage by 13.5, 11.5, 9.3, and 8.2%, respectively, over both seasons compared with control. The organic amendments surpassed inorganic regarding microbial biomass carbon, soil respiration rate, and dehydrogenase activity with the superiority of RSC, FYM, and rice husk over the control treatment. These soil restorations were favorably reflected in morpho-physio-biochemical parameters, yield, and its components for all the tested rice genotypes. The EHR1 is the superior genotype in terms of ion (Na+ and K+) selectivity, CAT activity, possessing lower proline and higher morpho-physiological responses, and productivity. The EHR1 had a considerable physiological effect on saline-sodic soil stress, producing higher yield (7.70 and 7.50 t ha−1) after treating with RSC or gypsum. This indicates that RSC outperforms other amendments in improving saline-sodic soils and enhancing rice productivity. Overall, a single application of rice straw compost (organic amendment) and gypsum or sulfur (inorganic amendment) is a viable sustainable approach for modulating saline-sodic soil’s physico-chemical and microbial properties and for boosting rice’s agronomic and physiological responses in an arid environment.

Review of the Responses of Various Soil Amendments in Sandy Soils

The primary constraints with sandy soils are low soil organic matter content, poor nutrient availability, heavy losses of applied nutrients and lower water holding capacity. Improving the productivity of sandy soils, particularly in developing countries, could be a viable solution to food insecurity and poverty. Large extent of sandy soil is one of the major constraints for crop production in the Eastern Province of Sri Lanka. Meanwhile, various soil amendments can be applied to improve the performances of cropping systems in sandy soils. Nevertheless, a comprehensive knowledge on which soil amendment would work better across different scales is not well known. To address this knowledge gap, this review was conducted using published literature. Systematic review approach was adopted, and the data were extracted from 65 highly relevant papers. The data were analyzed to calculate the percentage changes on crop yields, soil organic matter and soil carbon, in response to the applications of different soil amendments. The review highlighted the potential of several soil amendments to improve the crop performances in sandy soils. Interestingly, rice straw biochar and the municipal solid waste compost have greatly increased crop yields especially in rice at the rate of 0.9% w/w and 3% w/w in soil weight basis, respectively. Highest improvement in soil organic matter and soil carbon was observed under the applications of compost and spent grain, respectively. Therefore, rice straw biochar and compost could be evaluated to improve the productivity of sandy soils, especially in the Eastern region of Sri Lanka. Although the spent grain was promising, the availability for large scale applications may be limited in Sri Lanka. Testing of these soil amendments would require long-term experiments incorporating different crops and cropping systems. 
 Keywords: Compost, Biochar, Sandy soil, Soil amendments

UNVEILING THE NATURE OF CARBON DECOMPOSITION ON DIFFERENT ORGANIC MANURE SOURCES: THE IMPACT OF TEMPERATURE REGIMES IN A SUBTROPICAL CLIMATE

Organic sources are vital for crop nutrient management, but nutrient release from organic manure depends on temperature and other factors. We conducted a laboratory incubation study to investigate how temperature (15, 25, 35°C) affects the decomposition of common organic manure, which has not yet been explored in Bangladesh. The organic manures used in this study are poultry manure (PM), vermicompost (VC), bio-slurry (BS), cow dung (CD), water hyacinth compost (WHC) and rice straw compost (RSC), which were compared with a control treatment (only soil). Carbon mineralisation and CO2 emission from microbial respiration varied among organic manures and temperature regimes. The RSC- and WHC-treated soils had a higher C mineralisation than the other manures at 35°C. The mineralisation of C among the organic manures followed the order: RSC > WHC > CD > VC > BS > PM > control. Among the temperature regimes, C mineralisation followed the order 35°C > 25°C > 15°C. Manure mineralisation was associated with mineralisable C pools (carbon availability factor, Caf), and 16.4–36.5% organic C was released. Irrespective of temperature regimes, the highest easily mineralisable Caf was recorded in PM-amended soil, followed by VC-amended soil. RSC had the lowest Caf under all temperature regimes. The Caf values of all incubated manures were higher under a 35°C temperature regime. Compost preparation from organic manure and its utilisation as an integrated nutrient management component can play essential roles in mitigating climate change, reducing environmental degradation, and building more sustainable and resilient agrifood systems.

Humic acid biosynthesis and bacterial community evolution during aerobic composting of rice straw

In this study, the effects of inoculum ratio, substrate particle size and aeration rate on humic acid (HA) biosynthesis during aerobic composting of rice straw were investigated, respectively. The contents of total organic carbon, total nitrogen and HA, as well as lignocellulose degradation in the composting were evaluated, respectively. It is found that the maximal HA yield of 356.9 g kg−1 was obtained at an inoculum ratio of 20%, a substrate particle size of 0.83 mm and an aeration rate of 0.3 L·kg−1 DM min−1 in the process of composting. The changes of microbial communities and metabolic functions at different stages of the composting were also analyzed through high-throughput sequencing. The result demonstrates that Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria were the dominant phyla and their relative abundance significantly varied over time (p < 0.05), and Rhizobium, Phenylobacterium, Pseudoxanthomonas and Paenibacillus were positively related to HA content in the compost. Furthermore, the metabolic function profiles of bacterial community indicate that these functional genes in carbohydrate metabolism and amino acid metabolism were involved in lignocellulose biodegradation and HA biosynthesis. This work may be conducive to explore new regulation strategy to improve bioconversion efficiency of agricultural residues to applicable biofertilizers.Key points• Temperature, pH, TOC, TN and C/N caused a great influence on humic acids synthesis• The succession of the microbial community during the composting were evaluated• The metabolisms of carbohydrate and amino acids were involved in HA synthesisGraphical abstract

Effect of NH4+ and NO3− cooperatively regulated carbon to nitrogen ratio on organic nitrogen fractions during rice straw composting

The purpose of this study was to examine the effects of replacing urea with inorganic nitrogen on the organic nitrogen sequestration process and the mitigation of nitrogen loss during rice straw composting. These groups include a control group with urea addition (CK), a group with (NH4)2SO4 addition (NH), a group with KNO3 addition (NO), and a group with (NH4)2SO4 + KNO3 addition (NN). The results demonstrated that adding NH, NO, and NN significantly increased the content of bioavailable organic nitrogen in the composting. Furthermore, compared to the CK, the NH treatment reduced nitrogen loss by 8.41 %. Structural equation modeling revealed the correlation between bacterial communities and organic nitrogen fractions in different treatment groups. Comparisons of nitrogen efficacy and nitrogen loss indicated that adding (NH4)2SO4 was more effective during composting, which provided a meaningful research basis for rice straw composting.

Exchangeable Al, peanut growth, and nodulation on Ultisol Bogor as affected by ameliorant proportion of lime and organic matter

Ultisols are characterized as acid soils with high exchangeable Al as the primary constraint for plant growth. This study aimed to investigate the effect of the proportion of lime and organic matter in decreasing exchangeable Al on Ultisol Bogor and continued to observe the impact on the growth and nodulation of peanuts. The pot experiment used a completely randomized design with a single treatment of the addition of ameliorant consisting of 12 levels of the treatment of lime (calcite and dolomite), organic matter (dry cow dung and rice straw compost), and their combinations with three replications. The first step was applying the ameliorant and incubating for eight weeks, then continuing the cultivation of peanuts. Results showed that during incubation, the decrease in exchangeable Al levels varied between treatments, along with an increase in soil pH and available P. The treatments of calcite 100% (T1) and dolomite 100% (T2) showed the highest increase in soil pH and available P and the highest decrease in exchangeable Al. The result of plant growth showed that the highest plant dry weight, N-uptake, and P-uptake were obtained by the treatment of dolomite 25% + rice straw compost 25% + dry cow dung 25% + NPK 25% (T10), whereas the highest number and total weight of nodules were obtained by the rice straw compost 50% + dry cow dung 50% (T7) and dolomite 25% + rice straw compost 75% (T8).

Isolation and screening of potential lignocellulolytic microbes from Phra Nakhon Si Ayutthaya Province

Phra Nakhon Si Ayutthaya Province is an important area for rice cultivation in Thailand. However, large amounts of rice straw generated at harvest time are often burnt in the fields, causing environmental degradation and air pollution. To address this, rice straw composting by degrading microorganisms has been identified as an effective alternative for sustainable waste management, with potential applications in environmental biotechnology. For this study, 28 microorganism samples were collected from various sources in Phra Nakhon Si Ayutthaya Province, including a corrugated paper manufacturer, plant-cultivated soil, compost from dung, black soldier flies, and vermicompost. Lignocellulolytic microorganisms were screened for cellulase, xylanase, and manganese peroxidase production on agar plates and broth media using commercial and rice straw substrates. The lignocellulolytic activities were compared among the isolated and non-pathogenic microorganisms. A microbial consortium with high potential to degrade rice straw was identified, consisting of two thermophilic bacteria, Bacillus licheniformis BKT1 and BOT4, two mesophilic actinomycetes, Streptomyces ardesiacus AQ4 and An6, two thermophilic actinomycetes, Streptomyces thermoalcalitolerans APT3 and Streptomyces thermoviolaceus subsp. thermoviolaceus AQT2, and two fungi, Penicillium sp. Fh11 and Aspergillus sp. Fj6. This microbial consortium induced rapid composting of rice straw, thereby supporting sustainable agricultural waste management and reducing PM25 air pollution.

Rice Straw Compost and Husk Biochar as Growth Starters and In Vitro Heavy Metal Biosorbents

Soil microbial activity is known to increase with compost application, aiding in nutrient absorption by plants and the provision of growth-promoting chemicals. Biocar, derived from plant fires or through heavy metal biosorption, also plays a crucial role in soil improvement. Therefore, this study aimed to develop rice straw compost and husk biochar as growth starters and evaluate their potential for heavy metal biosorption in vitro. The experiment was conducted in Samarinda, East Kalimantan, Indonesia, from October 2023 to January 2024. Rice straw and husk were collected at several random points in previously determined active fields (Stage I Point 4). After characterizing the chemical and physical properties, the rice straw was composted, and the husk was biocharized. The incubation medium used was rice field soil from Samarinda, while straw compost, husk biochar, soil compounds, and heavy metals were evaluated at the Soil Science Laboratory, Mulawarman University. In addition, microbial analyses were performed at the Plant Pest and Disease Laboratory, Faculty of Agriculture, and Microbiology Laboratory, Faculty of Fisheries and Marine Sciences. The results showed that compost materials and biochar content strongly influenced the overall bacterial and fungal colonies. As the incubation time increased, the bacterial and fungal colonies decreased. During the initial two months of waste intake, the number of colonies significantly increased, showing a notable difference compared to periods before the addition of compost or biochar.

APPLICATION OF BIOSTIMULANTS BASED ON PADDY STRAW COMPOST AND INORGANIC FERTILIZER IN INCREASING SOIL FERTILITY AND RED CHILLI YIELD

Salinity due to abiotic stress can reduce the yield and productivity of agricultural crops. The negative effects of salinity stress can be overcome by adding soil organic matter that is enriched with beneficial microbes. The aim of this research is to evaluate the application of a combination of straw compost with biostimulant microbes and doses of N, P, K fertilizer which can increase soil fertility and red chili yields and can reduce the use of inorganic fertilizer doses on Inceptisols saline and non-saline soils. The research was designed using the Randomized Block Design with 14 treatments combination and three replications, namely control treatment, as well as a combination of rice straw compost without or with added biostimulants with reduced doses of N, P, K fertilizer on non-saline and saline soils (4 dS /m). The research results showed that the combination of straw compost treated with biostimulants with various levels of N, P, K fertilizer doses was able to increase plant N content, Phosphate Solubilizing Bacteria (PSB) population and red chili plant yields in both saline and non-saline Inceptisols. Biostimulants applied to straw compost can reduce the use of N, P and K fertilizer doses by up to ¼ of the recommended dose for the fruit weight of chili plants planted in saline Inceptisols soil

The Plant Growth Analysis of Cucumis sativus L. Affected by Various Types of Organic Matter

Organic matter can be used to increase the growth and metabolism activities of Cucumis sativus L. plants. Plant growth analysis is a simple method that can be used to determine physiological activities that support plant growth. The study aims to describe plant activities through plant growth analysis which is influenced by the use of organic matter. The research was conducted at the Experimental Garden, Faculty of Agriculture, Universitas Perjuangan Tasikmalaya. The study used a Completely Randomized Design - single factor (types of organic matters) i.e. control, rice straw compost, rice husk, leaf green compost, and cow manure. Four replications were used in this study. Based on our study, the application of organic matter significantly affects LAI 2 WAP, LAI 4 WAP, WC 2 WAP, WC 4 WAP, NAR, PGR, and HI. Cow manure, green leaf compost, and rice straw compost can increase LAI, while rice husk, rice straw, and green cow manure can increase WC. Furthermore, the application of rice husk and cow manure was able to increase in NAR, CGR, and HI. The increase NAR, CGR, and HI in this study was positively correlated with r= 0.622 and r= 0.284, respectively.

Shallot cultivation originated from true shallot seed (TSS) on Andisols enriched with various ameliorants

Application of soil ameliorants is important to improve Andisols properties and increase shallot productivity. The research objective is to determine the kind of ameliorant which the best effect on the growth and productivity of shallots originating from TSS in Andisols Lembang, West Java. The experiment was conducted in Margahayu Research Station, Lembang, West Java from January to May 2021. A randomized block design (RBD) with 6 treatments and 5 replications was set up in the field. Treatments include control (no ameliorant), 20 tons/ha of horse manure, 10 tons/ha of rice straw compost, 10 tons/ha of bamboo leaf compost, 10 tons/ha of husk biochar, and 5 kg/ha humic acid. The results showed that vegetative performance and yield of true shallot seed-based shallot variety of Trisula in Andisols enriched with rice straw compost was higher than in other ameliorant treatments. Additionally, nutrient uptake in rice straw compost treatment was also higher than in other ameliorant treatments.

Composting of Rice Straw–Based Materials using Aerobic Bioactivator Isolated from Rice Straw, Mahogany Bark and Cassava Peels

Compost is one of organic fertilizers that play an important role in maintaining soil health and supporting sustainable agriculture. Diverse aspects could be developed to increase the quality of compost. This study aims to compare the quality of compost produced by using two different bioactivators, namely aerobic bioactivator RMC (the microbial consortia isolated from composted rice straw, mahogany bark and cassava peels + additional supplement) and fermentative bioactivator (EM4 + molasses) in the composting of the mainly rice straw-based materials. Composting was conducted using a single factor completely randomized design consisting of five levels as follows: C0 (control, rice straw); C1 (rice straw + bioactivator EM4 + molasses); C2 (rice straw + bioactivator RMC + additional supplement); C3 (rice straw + cow dung + bioactivator RMC + additional supplement); C4 (leaf litter + cow dung + bioactivator RMC + additional supplement, as comparison treatment with no rice straw). Among the treatments of C0, C1 and C2, composting the same rice straw material but different bioactivators, C2 showed the highest compost quality and decomposition rate. Among the other three treatments of C2, C3 and C4 composting different materials but using the same bioactivator, C3 showed the highest compost quality, but the three treatments showed the same high decomposition rate. Based on the characteristics of the compost product, including nutrient content, the treatment C3 produced the highest quality, followed by C4 and then C2. Both bioactivators EM4 + molasses and RMC+ additional supplement tended to increase total bacteria, fungi, nitrogen-fixing bacteria and phosphate-solubilizing microbiota in the compost products compared to the control without bioactivator. A set of aerobic bioactivator RMC plus additional supplement serve as one strategy to accelerate the composting process and to enhance the compost quality.

Advancing Energy Recovery from Sugarcane Leaf via Two-Stage Anaerobic Digestion for Hydrogen and Methane Production: Impacts on Greenhouse Gas Mitigation and Sustainable Energy Production

This study aims to enhance energy recovery from sugarcane leaf (SCL) through two-stage anaerobic digestion (TSAD) for hydrogen and methane production. The influence of hydraulic retention time (HRT) on this process was investigated. Optimal conditions established through batch experiments (5% total solids (TS) (w/v) and rice straw compost inoculum) were applied in semi-continuous stirred tank reactors (CSTR-H2 and CSTR-CH4). Remarkably, the highest production rates were achieved with HRTs of 5 days for CSTR-H2 (60.1 mL-H2/L·d) and 25 days for CSTR-CH4 (238.6 mL-CH4/L·d). Microbiological analysis by 16s rRNA sequencing identified Bacillus as predominant in CSTR-H2 followed by Lactobacillus and Clostridium. Utilizing SCL for TSAD could reduce greenhouse gas (GHG) emissions by 2.88 Mt-CO2 eq/year, compared to open-field burning, and mitigate emissions from fossil-fuel-based power plants by 228 kt-CO2 eq/year. This research underscores the potential of TSAD for efficient energy recovery and significant GHG emission reductions.

Pemanfaatan Kompos Jerami Padi dalam Pengembangan Bawang Merah di Ultisol Dataran Rendah Kota Padang

Shallots are a high-value horticultural commodity. But so far, they have been mostly developed in the highlands. Shallots are plants that like areas with hotter air temperatures, so they are suitable for cultivation in the lowlands. Still, the soil that is widely available in the lowlands of the city of Padang is Ultisol. Ultisol contains high clay, so the soil becomes dense, the available nutrients are low, and the ground has difficulty passing water. Using Ultisol as a land for planting shallots, it requires using organic fertilizer in large doses. One of the agricultural waste products that is available and has yet to be widely used in Lambung Bukik Village is rice straw. Rice straw is a waste that is difficult to decompose. Therefore, it is necessary to use a decomposer to get compost faster. Training on making rice straw compost and making demonstration plots was carried out in Lambung Bukik, Padang City, to support the development of shallot cultivation on lowland Ultisol. Farmers are very enthusiastic about learning to cultivate shallots and making organic fertilizer from rice straw.

Identifying the fate of Cd passivation during the long-term composting of rice straw: role of humic substances

Identifying the fate of Cd passivation during the long-term composting of rice straw: role of humic substances

Compost of peanuts residue and rice straw compost on soil Nitrogen forms and upland rice yield

&lt;p&gt;This study provides an innovation in making compost from rice straw (low quality) mixed with peanut residue (high quality) to improve the quality of rice straw compost. The purpose of this research was to discover the optimum composition of a mixture of peanut residue and straw for mineralization, absorption, and Nitrogen Use Efficiency (NUE) and its effect on upland rice plants. The study was conducted in three stages. The first stage determined the quality of five compost mixtures: C1, C2, C3, C4, and C5. The second phase of testing for cumulative N minerals was performed after 1, 2, 4, and 8 weeks of incubation. The third stage examined the impact of the compost mixture on the growth and yield of upland rice in comparison with two treatments, namely the control and NPK fertilizer. The results showed a similarity in the forms of mineralization, where the cumulative N mineral increased with the addition of peanut residue to the compost mixture. The use of a mixture of peanut residue and rice straw compost increased net mineralization by 37.27% (C5) to 59.48% (C1), N uptake by 49.19% (C5) to 62.95% (C3), and NUE by 15.04% (C4) to 51.48% (C3). A strong relationship was detected between the quality of the compost and the forms of N in the soil, particularly the nitrate content, total N minerals, and N microbial biomass, with correlation coefficients of 0.92, 0.88, and 0.94, respectively. A strong to very strong relationship was detected between N form and N uptake (r = 0.84), plant height (r = 0.79), number of tillers (r = 0.78), yield of rice plants (r = 0.93 (plant total dry weight), and r = 0.76 (grain weight). The optimum N uptake, NUE, and yield of upland rice were shown by C3 treatment of 405.28 mg pot&lt;sup&gt;-1&lt;/sup&gt;, 42.21%, and 6.19 tons ha&lt;sup&gt;-1&lt;/sup&gt;, respectively.&lt;/p&gt;

Residue recycling options and their implications for sustainable nitrogen management in rice–wheat agroecosystems

BackgroundIn the Indo-Gangetic Plain, rice–wheat is the most extensively practiced crop rotation. The escalating issue of crop residue burning, particularly rice straw, and the necessity to lower the exorbitant expenses associated with fertilizer inputs stand out as significant challenges for farmers in the region. A well-suited integrated nutrient management (INM) strategy that focuses on recycling crop residues can serve as a solution to address these issues. Such a strategy not only mitigates air pollution resulting from residue burning but also helps combat water pollution due to nitrate losses from agroecosystems. Field experiments were used to evaluate the suitability of eight INM-modules that included various combinations of inorganic fertilizer rates (50%, 100%, 150% of recommended dose), crop residues (wheat and rice stubble retention at 30 cm standing stubble equivalent to 1/3 the straw yield), rice straw compost (RSC), farmyard manure (FYM), and green manuring (GM), compared to 100% recommended dose of fertilizers (F) and no fertilizer application.ResultsThere was a considerable improvement in nitrogen mineralization, grain yields, and nitrogen use efficiency under GM + RSC-F50 and GM + FYM-F50. These INM modules would permit a 50% reduction in the use of chemical fertilizers. There was a little yield penalty with in situ rice residue incorporation at 100% F; however, this could be overcome with 150% F fertilizer application. In situ retention of wheat straw with a full application of fertilizer resulted in steadily rising crop yields over time. Changes in the redox potential, soil pH, and soil organic carbon best accounted for the observed trajectories in nitrogen use efficiency.ConclusionThe most promising INM modules for adoption by farmers in the Indo-Gangetic Plain to judiciously use crop residues and curtail chemical fertilizer inputs are green manuring with Sesbania aculeata + rice straw compost at 5 t ha−1 + only 50% of recommended dose of fertilizers (GM + RSC-F50), and green manuring with Sesbania aculeata + farmyard manure at 5 t ha−1 + only 50% of recommended dose of fertilizers (GM + FYM-F50). Sole incorporation of crop residues without nitrogen augmentation from other sources might not help curtail chemical fertilizer use. Composting rice straw, which otherwise is widely burnt, proved a useful nitrogen source and a vital component of INM. Waste rice straw composting at the community scale and its application as a nutrient source can help achieve sustainable nitrogen management in the agroecosystems of Indo-Gangetic Plain.

Mode and experiments of a straw ditch-burying returning and maturing in cold region of Northeast China

The current agronomic model of returning straw litter to soil (straw returning) involves crushing and mixing the straw with soil, which leads to shallow burial and ineffective decomposition of the straw. To address this issue in the cold region of Northeast China, this study proposed a method of burying and composting rice straw in furrows for returning to the field, and developed a matching machinery. Based on long-term experiments of burying straw in soil in spring and autumn, in this study, the operating parameters, postoperative straw decomposition effects, and influence of soil bulk density were analyzed. The results showed that the straw returning rate was inversely proportional to the forward speed and proportional to the furrow opening rotation speed and exhibited an increasing-then-decreasing trend with increasing collecting rotation speed. Taking into account both straw returning rate and operational efficiency, the recommended optimal operating parameters for the machinery unit were a forward speed of 0.4 m s−1, a raking speed of 180 r min−1, and a ditching speed of 420 r min−1. Under the spring model of burying straw in soil, straw treated with the composting agent was more likely to be fully decomposed in a short period, with a maximum total decomposition rate of up to 97.23%. Burying straw in soil effectively reduced soil bulk density, and straw returning in spring was more conducive to improving soil physical properties than straw returning in autumn. The value of this research lies in the integration of agricultural machinery and agronomy, providing insights for the development and design of related equipment, as well as offering a new approach for the effective treatment and utilization of straw in cold regions.

Silica sources for arsenic mitigation in rice: machine learning-based predictive modeling and risk assessment.

Arsenic (As) is a well-known human carcinogen, and the consumption of rice is the main pathway for the South Asian people. The study evaluated the impact of the amendments involving CaSiO3, SiO2 nanoparticles, silica solubilizing bacteria (SSB), and rice straw compost (RSC) on mitigation of As toxicity in rice. The translocation of As from soil to cooked rice was tracked, and the results showed that RSC and its combination with SSB were the most effective in reducing As loading in rice grain by 53.2%. To determine the risk of dietary exposure to As, the average daily intake (ADI), hazard quotient (HQ), and incremental lifetime cancer risk (ILCR) were computed. The study observed that the ADI was reduced to one-third (0.24 μg kg-1bw) under RSC+SSB treatments compared to the control. An effective prediction model was established using random forest model and described the accumulation of As by rice grains depend on bioavailable As, P, and Fe which explained 48.5, 5.07%, and 2.6% of the variation in the grain As, respectively. The model anticipates that to produce As benign rice grain, soil should have P and Fe concentration more than 30 mg kg-1 and 12 mg kg-1, respectively if soil As surpasses 2.5 mg kg-1.