Application Of Organic Residues Research Articles

Mix-method toolbox for monitoring greenhouse gas production and microbiome responses to soil amendments

In this study, we adopt an interdisciplinary approach, integrating agronomic field experiments with soil chemistry, molecular biology techniques, and statistics to investigate the impact of organic residue amendments, such as vinasse (a by-product of sugarcane ethanol production), on soil microbiome and greenhouse gas (GHG) production. The research investigates the effects of distinct disturbances, including organic residue application alone or combined with inorganic N fertilizer on the environment. The methods assess soil microbiome dynamics (composition and function), GHG emissions, and plant productivity. Detailed steps for field experimental setup, soil sampling, soil chemical analyses, determination of bacterial and fungal community diversity, quantification of genes related to nitrification and denitrification pathways, measurement and analysis of gas fluxes (N2O, CH4, and CO2), and determination of plant productivity are provided. The outcomes of the methods are detailed in our publications (Lourenço et al., 2018a; Lourenço et al., 2018b; Lourenço et al., 2019; Lourenço et al., 2020). Additionally, the statistical methods and scripts used for analyzing large datasets are outlined. The aim is to assist researchers by addressing common challenges in large-scale field experiments, offering practical recommendations to avoid common pitfalls, and proposing potential analyses, thereby encouraging collaboration among diverse research groups.•Interdisciplinary methods and scientific questions allow for exploring broader interconnected environmental problems.•The proposed method can serve as a model and protocol for evaluating the impact of soil amendments on soil microbiome, GHG emissions, and plant productivity, promoting more sustainable management practices.•Time-series data can offer detailed insights into specific ecosystems, particularly concerning soil microbiota (taxonomy and functions).

Sustainable basmati rice yield and quality enhancement through long-term organic nutrient management in the Indo-Gangetic Plains

Context or problemThe extensive use of chemical fertilizers and pesticides in modern agriculture, particularly since the green revolution, has led to profound consequences for agricultural ecosystems. This approach, while initially boosting yields, has disrupted soil health, biodiversity, and environmental balance. Moreover, it contributes silently to global climate change by releasing greenhouse gases. These challenges underscore the urgent need for a shift towards sustainable agricultural practices to safeguard soil health, biodiversity, and human nutrition while mitigating the impacts of climate change. Objective or research questionThe primary objective of this study is to assess the impact of the long-term (seventeen years) application of organic nutrient management on the physicochemical properties of basmati rice soil and its nutritional quality. The study aims to understand the effectiveness of different organic nutrient management practices in mitigating the negative consequences associated with conventional agricultural practices. MethodsThe experiment used a strip-plot design with three replications, assigning two cropping systems (basmati rice-wheat-green gram and basmati rice-wheat-sesbania) to vertical strips. Seven nutrient management practices, including control, farmyard manure (FYM), vermicompost, farmyard manure + crop residues, vermicompost + crop residues, farmyard manure + crop residues + biofertilizers, and vermicompost + crop residues + biofertilizers [nitrogen-fixing Azospirillum, phosphorus-solubilizing bacteria (PSB), potassium-solubilizing bacteria (KSB), and a cellulolytic culture (Aspergillus awamori, Trichoderma viride, Phanerochaete chrysosporium, and Aspergillus wululens)] were applied to the horizontal strips. ResultsThe findings show that the cropping system with sesbania green manure significantly improved soil physicochemical attributes, nutritional content, and basmati rice yield compared to the green gram-based system. Continued application of organic manures, crop residues, and biofertilizers notably enhanced soil fertility, grain quality, and basmati rice productivity. The combined use of vermicompost, wheat residue, biofertilizers, and sesbania green manure treatment increased organic carbon content by 78.7% over the control, and soil available nitrogen, phosphorus, and potassium by 38.3–54.9%, 57.6–143.8%, and 27.9–64.1%, respectively. Additionally, it augmented diethylenetriamine pentaacetic acid extractable iron, zinc, manganese, and copper content by up to 44.2%, 28.5%, 57.9%, and 71.0%, respectively. Co-application of the above organic sources also significantly enhanced grain and straw yields by 74.5–80.1% and 46.1–50.0%, respectively, compared to the control. ConclusionsEnhancing Basmati rice yield and quality in the Indo-Gangetic Plains can be sustainably achieved through sesbania green manuring and organic practices. Positive correlations with key soil parameters emphasize the significance of organic farming for long-term sustainability. Implications and significanceThe study suggests that adopting organic practices, including sesbania green manuring and combining organic inputs, can alleviate the adverse effects of conventional farming on soil health, biodiversity, and climate change. This aligns with the broader goal of establishing sustainable production and consumption in basmati rice-based cropping systems.

Assessment and Characterization of Agricultural Salt-Affected Soils around Abaya and Chamo Lakes, South Ethiopia Rift Valley

Soil salinity/sodicity is becoming a challenge for crop production in Ethiopia’s semi-arid and arid regions. However, more information on soil salinity/sodicity needs to be available around Abaya and Chamo Lakes, South Ethiopia Rift Valley. This study aimed to assess and characterize soil salinity/sodicity and determine salt-affected soils’ morphological, physical, and chemical properties. The representative soil pits that were 60 ∗ 60 ∗ 60 cm in size were examined, and samples were taken from 0–20, 20–40, and 40–60 cm depths based on the criteria set for agricultural salt-affected soil studies. The soil properties determined include soil color, structure, consistency, bulk density, particle density, porosity, texture, pH, EC, SAR, ESP, CEC, BS, OC, TN, available P, CaCO3−, exchangeable bases, and soluble ions (Na+, Ca2+, Mg2+, K+, Cl−, SO4−2, NO3−, CO3−2, and HCO3−. The soil-analyzed results were rated and interpreted following a guide to standardized analysis methods for soil data. The results of this study reveal that the soils had considerable heterogeneity in soil morphological, physical, and chemical properties. The soils of the study site were highly alkaline and had very high sodium content, very high CEC value, and low levels of organic carbon and exchangeable calcium. The dominant soluble cation was sodium, followed by magnesium, calcium, and potassium in all soil depths of the pits. Similarly, Cl− was dominant among the anions throughout the soil depth, followed by HCO3−, SO42−, and NO3−. The findings of this study imply that removing sodium and salts from the soil depth may improve the salt-affected soils’ productivity in the study area. Application of organic amendments, including manures and crop residues, may also be beneficial in increasing fertility and organic matter content.

The synergy of dark septate endophytes and organic residue on Isatis indigotica growth and active ingredients accumulation under drought stress

Drought is a major abiotic stress factor affecting plant growth and production, while utilizing beneficial endophytic fungi is one of the most promising strategies for enhancing plant growth and drought tolerance. In the present study, a pot experiment was conducted to investigate the beneficial effects of dark septate endophytes (DSE) (Acrocalymma aquatica and Alternaria alstroemeriae) combine with organic residues from sterilized or non-sterilized fermented corn straw by Trichoderma afroharzianum on the growth and drought resistance of Isatis indigotica. Drought stress (30% field water capacity) reduced the shoot biomass, root biomass, and epigoitrin content of I. indigotica by 34.30%, 80.85%, and 16.51%, respectively. The DSE inoculation alone increased shoot biomass and epigoitrin content under well-watered condition (70% field water capacity) by 13.75%− 65.98% and 52.33%− 67.59%, respectively, and shoot biomass under drought stress by 37.27%− 84.91%. The organic residues application alone increased root biomass under well-watered condition and drought stress by 71.88%− 107.06% and 463.61%− 678.69%, respectively. The mixed application of DSE and organic residues increased root biomass and epigoitrin content under well-watered condition by 66.79%− 144.66% and 89.02%− 136.63%, respectively, and under drought stress by 410.66%− 580.49% and 28.26%− 88.37%, respectively. Structural equation modeling demonstrated that DSE inoculation, organic residue application, and the mixed application improved the growth of I. indigotica under drought stress through different direct and indirect pathways. Variation partitioning showed that DSE was the primary factor improving the epigoitrin content, and organic residue was the primary factor influencing plant biomass and morphological parameters. The mixed application of DSE and organic residue had further synergistic effects on soil enzyme activities, soil organic matter, root biomass, and epigoitrin content, especially the mixed application of A. aquatica and sterilized organic residue. These results contribute to a further understanding of the ecological function of DSE in dryland soils and reveal the synergistic application value of DSE and organic residue for medicinal plant cultivation.

Organic residues and their impact on soil health, crop production and sustainable agriculture: A review including bibliographic analysis

AbstractDespite their potential as a sustainable source of soil nutrients and organic matter, waste organic residues are often discarded rather than utilized in agriculture. This review examines the current state‐of‐the‐art in the application of organic residues in agricultural production systems by analysing trends and results in published research conducted on their use for soil health and crop production purposes. For this, a bibliographic analysis was conducted on 81 papers collected from the Web of Science database. Our research shows a growing trend in the field, particularly in recent years, with articles from India, China and the United States at the forefront. The most commonly evaluated organic residues were compost, animal manure, crop residues, municipal solid waste and biochar. Soil pH, bulk density and especially organic matter/total organic carbon (TOC) were the chemical, physical and biological attributes most frequently evaluated, respectively. This review indicates that the application of organic residues improves soil health, positively affecting crop productivity in crops such as maize, wheat and rice. However, further research is needed to address the potential risk of soil contamination from potentially toxic metals (PTMs) associated with organic residues, as well as to identify best practices to guarantee food safety and environmental preservation.

Impact, adaptation, and mitigation of climate change in Indian agriculture.

Climate change poses serious risks to Indian agriculture as half of the agricultural land of the country is rainfed. Climate change affects crop yield, soil processes, water availability, and pest dynamics. Several adaptation strategies such as heat- and water stress-tolerant crop varieties, stress-tolerant new crops, improved agronomic management practices, improved water use efficiency, conservation agriculture practices and improved pest management, improved weather forecasts, and other climate services are in place to minimize the climatic risks. The agriculture sector contributes 14% of the greenhouse gas (GHG) from the country. Mitigation of GHG emission from agriculture can be achieved by changing land-use management practices and enhancing input-use efficiency. Experiments in India showed that methane emission from lowland rice fields can be reduced by 40-50% with alternate wetting and drying (AWD), growing shorter duration varieties, and using neem-coated urea according to soil health card (SHC) and leaf color chart (LCC). Dry direct-seeding of rice, which does not require continuous soil submergence, can reduce methane emission by 70-75%. Sequestration of carbon (C) in agricultural soil can be promoted with the application of organic manure, crop residues, and balanced nutrients. India has taken several proactive steps for addressing the issues of climate change in agriculture. Recently, it has also committed for reducing GHG emission intensity by 45% by 2030 and achieving net zero emission by 2070. The paper discusses the major impacts of climate change, potential adaptation, and mitigation options and the initiatives of Govt. of India in making Indian agriculture climate-smart.

Application of natural organic residues in the remediation of metals from e-waste

Contaminants, such as potentially toxic metals from e-waste, have been affecting soil, water and ecosystems throughout the world. Thus, the search for low cost natural substances, able to complex such metals, is a matter of both environmental and economic interest. Humic substances (HS) are the main natural organic complexing agents in ecosystems, and their alkaline extraction leads to a poorly soluble residue, which is often discarded, in spite of its great potential for chelating potentially toxic metals. Since both the structure and complexing capacity of HS might be significantly affected by the way of extraction, this study comparatively evaluated the implications of exhaustive and non-exhaustive extractions on physical–chemical and structural properties of different natural organic residues (NOR) obtained. Furthermore, adsorption studies were carried out in order to compare the influence of different extractions on the resulting NOR capacities to retain copper ions. The milder extractions, involving non-exhaustive procedures, led to a NOR with better copper adsorption, which was then selected to test the retention of copper from an e-waste leachate. Results evidenced the potential use of NOR for copper removal (340 μ g Cu 2 + g −1 of NOR), as well as other potentially toxic metals, such as iron, manganese and chromium, thus showing a promising application of this material in the environmental remediation of soils and waters. • Low-cost alternatives for environmental remediation of metals from soil and water. • The extraction method affects the complexing capacity of natural organic residues. • Natural organic residues as adsorbents of potentially toxic metals from e-waste.

Prediction of Cadmium Threshold Using Regression Model for Soils Under Cd-Containing Organic Residue Application

Prediction of Cadmium Threshold Using Regression Model for Soils Under Cd-Containing Organic Residue Application

Effects of residue types and plastic mulch on earthworm aporrectodea trapezoides (Duges, 1828) within mesocosms at a salt-affected soil

ABSTRACT Earthworm colonization is an effective management practice to improve soil conditions. In a salt-affected reclamation soil, we conducted a mesocosm experiment to test the effects of organic residue application (no organic residues, clover residues or sheep manure) and plastic film (mulching or no mulching) on the survival, biomass and production of earthworms (Aporrectodea trapezoides (Duges, 1828)). Results showed that application of organic residues yielded a higher survival rate (37–100%) and biomass (0.43–0.98 g) of earthworms than the treatments without organic residue, regardless of plastic mulch. Moreover, the application of sheep manure significantly increased earthworm survival (58%) and biomass (160%) compared to the application of clover residues, which may be due to high soil available resources and nutrients in the soils with sheep manure. No significant differences (p = 0.26) in the survival rate (37–100% and 47–82%) or biomass of A. trapezoides were observed between the mulch and no-mulch treatments. This study indicated that animal manure out-performed clover residues in promoting the growth and survival of A. trapezoides in a reclaimed, salt-affected soil. Moreover, plastic film mulching improved soil moisture, but had no effect on the survival and biomass of A. trapezoides.

Deforestation-free land-use change and organic matter-centered management improve the C footprint of oil palm expansion.

In recent decades, mounting evidence has indicated that the expansion of oil palm (OP) plantations at the expense of tropical forest has had a far pernicious effect on ecosystem aspects. While various deforestation‐free strategies have been proposed to enhance OP sustainability, field‐based evidence still need to be consolidated, in particular with respect to savanna regions where OP expansion has recently occurred and that present large area with potential for OP cultivation. Here we show that the common management practice creating within the plantation the so‐called management zones explained nearly five times more variability of soil biogeochemical properties than the savanna land‐use change per se. We also found that clayey‐soil savanna conversion into OP increased total ecosystem C stocks by 40 ± 13 Mg C ha−1 during a full OP cultivation cycle, which was due to the higher OP‐derived C accumulated in the biomass and in the soil as compared to the loss of savanna‐derived C. In addition, application of organic residues in specific management zones enhanced the accumulation of soil organic carbon by up to 1.9 Mg ha−1 year−1 over the full cycle. Within plantation, zones subjected to organic amendments sustained similar soil microbial activity as in neighboring savannas. Our findings represent an empirical proof‐of‐concept that the conversion of non‐forested land in parallel with organic matter‐oriented management strategies can enhance OP agroecosystems C sink capacity while promoting microbe‐mediated soil functioning. Nonetheless, savannas are unique and threatened ecosystems that support a vast biodiversity. Therefore, we suggest to give priority attention to conservation of natural savannas and direct more research toward the impacts of the conversion and subsequent management of degraded savannas.

Anthropogenic Soil Experiment in Brazil Amazon: Changes in Soil Physical Properties by Organic Residues

ABSTRACT Archeological Dark Earths, known in the Brazilian Amazon as Terra Preta de Índio are fertile and structured soils considered as a potential model for sustainable agriculture. In order to recreate these soils a field experiment, named New Dark Earth, was set up in 2003 in the municipality of Tailândia, state of Pará, northern Brazil. The treatments consisted of the application of organic residues (wastes from local industries) in a loamy sand soil: cattle bones, wood charcoal, shredded wood blades, and the control. The objective of this study was to evaluate the effect of these residues on soil physico-hydrological properties. The results showed that the residues did not significantly increase the soil organic carbon content. Only the wood charcoal resulted in some improvements in soil physico-hydrological properties, such as lower soil bulk density and higher total and microporosity, which was mainly attributed to the high porosity of this material. Consequently, it also presented more available water. For now, it was concluded that despite the three residues are widely available in the region, the use of wood charcoal seems to be the best alternative to bring improvements to the soil physical properties, mainly soil water retention. However, more studies need to be carried out.

Enhancement of Growth, Flowering and Corm Freesia Hybrida Plant via Rice Organic Residue Application and Chelated Zinc Spray

A pot trial was conducted to identify the effect of adding rice organic residues (ROR) to the potting soil and spraying chelated zinc (CZn) on the growth, flowering, and corm characteristics of the Freesia hybrida plant. An RCBD experiment was adopted with two factors and three replicates. ROR comprised three levels (0, 4, and 8%), and CZn included three concentrations (0, 20, and 40) mg.L−1. The findings revealed that applying ROR at 8% and spraying CZn at 20 mg.L−1 significantly increased leaf number, shoot dry weight, total chlorophyll content in fresh leaves, and total soluble carbohydrate content in dry leaves (6.66 leaves. plant−1, 8.76 g DW, 48.79 mg.100 g−1 FW, and 1.50 g DW) respectively. Also, the same treatment combination realized significant results for the number of florets per inflorescence, floret diameter, floret vase life, number of corms per plant, and corm diameter by (12.85 florets. inflorescence−1, 7.03 cm, 8 days, 3.66 corms. plant−1, and 2.33 cm) consecutively. Further, adding ROR at 8% and spraying CZn at 40 mg.L−1 significantly increased the number of inflorescences (5.33 inflorescences. plant−1) and inflorescence length (39.10 cm).

Steering microbiomes by organic amendments towards climate-smart agricultural soils

We steered the soil microbiome via applications of organic residues (mix of cover crop residues, sewage sludge + compost, and digestate + compost) to enhance multiple ecosystem services in line with climate-smart agriculture. Our result highlights the potential to reduce greenhouse gases (GHG) emissions from agricultural soils by the application of specific organic amendments (especially digestate + compost). Unexpectedly, also the addition of mineral fertilizer in our mesocosms led to similar combined GHG emissions than one of the specific organic amendments. However, the application of organic amendments has the potential to increase soil C, which is not the case when using mineral fertilizer. While GHG emissions from cover crop residues were significantly higher compared to mineral fertilizer and the other organic amendments, crop growth was promoted. Furthermore, all organic amendments induced a shift in the diversity and abundances of key microbial groups. We show that organic amendments have the potential to not only lower GHG emissions by modifying the microbial community abundance and composition, but also favour crop growth-promoting microorganisms. This modulation of the microbial community by organic amendments bears the potential to turn soils into more climate-smart soils in comparison to the more conventional use of mineral fertilizers.

Organic phosphorus forms in a tropical sandy soil after application of organic residues of different quality

The addition of organic materials can improve soil fertility and phosphorus availability in agricultural soils. However, knowledge of organic P (Po) forms in soils with the incorporation of different quality residues is limited. This study investigated Po forms and determined the relationship between Po and soil properties in tropical sandy soils after application of local organic residues of different qualities, including groundnut stover (GN), tamarind leaf litter (TM), dipterocarp leaf litter (DP), and rice straw (RS). The Po forms were determined using a sequential extraction procedure and 31P nuclear magnetic resonance (NMR) spectroscopy. Addition of residues, regardless of quality, had little effect on total Po accumulation, but it affected soil Po forms. Labile Po was a dominant form after incorporating high-quality residue (high nitrogen, low lignin, and low polyphenols) (e.g., GN), whereas nonlabile humic-Po and residual Po were dominant forms in soils treated with lower-quality residue with low N, high lignin, and high polyphenols (e.g., TM, DP, and RS). Using 31P NMR spectroscopy, orthophosphate and phosphate monoester (mono-P) were the major forms of inorganic P and organic P in all residue-treated soils, respectively. High-quality residue incorporation increased diester, DNA, and teichoic acid. The results showed that phosphonate occurred in GN soil because of acidic conditions occurring when GN was applied. The Po forms in lower-quality residue additions were dominated by mono-P because these residues had elevated contents of lignin and polyphenols, which has the potential to produce humic substances that form complexes with soil minerals. Furthermore, the nonlabile Po had a positive association with available P in tropical sandy soils.

Influence of Application of Organic Residues of Different Biochemical Quality on Phosphorus Fractions in a Tropical Sandy Soil

Understanding phosphorus (P) dynamics in tropical sandy soil treated with organic residues of contrasting quality is crucial for P management using organic amendments. This research determined P fractions in a tropical sandy soil under the application of organic residues of different quality, including groundnut stover (GN), tamarind leaf litter (TM), dipterocarp leaf litter (DP), and rice straw (RS). The organic residues were applied at the rate of 10 t DM ha−1 year−1. The P fractions were examined by a sequential extraction procedure. Organic residue application, regardless of residue quality, resulted in P accumulation in soils. For unamended soil, 55% of total P was mainly associated with Al (hydr)oxides. Organic residue application, regardless of residue quality, diminished the NH4F-extractable P (Al-P) fraction, but it had a nonsignificant effect on NaOH-extractable P (Fe-P). The majority of Al-P and Fe-P fractions were associated with crystalline Al and Fe (hydr)oxides. NH4Cl-extractable P (labile P), NaHCO3-extractable P (exchangeable P and mineralizable organic P), HCl-extractable P (Ca-P), and residual P fractions in soil were significantly increased as a result of the incorporation of organic residues. The application of organic residues, particularly those high in ash alkalinity, increase soil pH, labile P, and Ca-P fractions. In contrast, applications of residues high in lignin and polyphenols increase residual P fraction, which is associated with organo-mineral complexes and clay mineral kaolinite.

Nutrient composition of diverse organic residues and their long-term effects on available nutrients in a tropical sandy soil

Intensive use of sandy soils for agriculture leads to significant land degradation. The application of locally available organic residues can improve soil fertility, particularly in the context of organic farming practices. This research examined nutrient concentrations in locally available organic residues with different biochemical compositions/qualities and investigated the effects of long-term application of these residues on available nutrients, such as P, K, Ca, Mg, Fe, Mn, and Zn, as well as on total organic carbon (TOC) accumulation in tropical sandy soil. A field experiment was conducted in Northeast Thailand, where four local organic residues, groundnut stover (GN), tamarind leaf litter (TM), dipterocarp leaf litter (DP), and rice straw (RS), had been applied annually for 22 years. These organic residues were acidic (pH 3.7–5.8). The macronutrients N, P, and K were present at elevated levels in the high-quality organic residue GN, whereas medium-quality TM and low-quality RS and DP were dominated by the macronutrients Ca and Mg and the micronutrients Fe, Mn, and Zn. The incorporation of organic residues, particularly TM, resulted in the accumulation of TOC. Furthermore, long-term incorporation of TM increased soil pH, whereas incorporation of GN, DP, and RS did not. The higher increase in the soil pH of TM soil is likely because TM contains higher levels of ash alkalinity compared to other residues. The application of medium-quality TM increased the soil available P, Ca, and Mg, whereas low-quality organic residue RS and DP applications increased the concentrations of soil micronutrients (e.g., Mn and Zn). However, long-term applications of local organic residues did not increase available K in the sandy soil.

Reductive soil disinfestation incorporated with organic residue combination significantly improves soil microbial activity and functional diversity than sole residue incorporation.

Reductive soil disinfestation (RSD) is an effective agricultural practice to eliminate soil-borne pathogens that heavily relies on the organic substrate used. However, the influences of combined application of organic residues on disinfestation efficiency, soil microbiomes, and their associated functional characteristics are still not well-characterized. In this work, four treatments, i.e., untreated soil (CK), RSD with 15 t ha-1 sugarcane bagasse (SB), bean dregs (BD), and their combinations (1:1, SB+BD), were conducted to investigate their influence on disinfestation efficiency, microbial functional diversity, community diversity, and composition using Biolog analysis, real-time PCR, and high-throughput sequencing. The SB+BD treatment had synergetic effects on soil microbial activity, metabolic activity, and functional diversity with similar efficacy in pathogen elimination and soil salinization alleviation, as compared to the SB and BD treatments. Moreover, the SB+BD treatment distinctly altered the structure and composition of bacterial and fungal communities, especially enriched the core microbiomes associated with soil general functions such as organic decomposition and nitrate removal. The SB+BD treatment also strengthened the soil specific functions including disease suppression through the regulation of unique microbiomes. In addition, the microbial richness, diversity, and evenness were significantly higher in the SB+BD-treated soil as compared to the SB- and BD-treated soils. Taken together, RSD incorporated with organic residue combination not only efficiently restore the degraded soils, but also considerably improve soil functions, which may benefit to the health for the future plant generations. KEY POINTS: • Organic residue combination effectively declines pathogen density. • Organic residue combination improves soil microbial activity and functional diversity. • The enriched core microbiome is responsible for soil general functions. • The induced unique microbiome is important for soil specific functions.

Changes in some chemical properties of saline-sodic soils over time as affected by organic residues: An incubation study

<p>Salinization and sodification of agricultural lands in arid and semi-arid regions of the world are two limiting factors in the crop production. This study was conducted to evaluate the effect of readily available agricultural residues on changing some chemical properties of saline-sodic soils. Wheat, potato, sunflower, and canola residues were separately added into three saline-sodic soils at a rate of 2% by weight and thoroughly mixed with soils. Control and treated soils were incubated for 168 days at a constant moisture and temperature. The pH, electrical conductivity (EC), soluble cations, available nitrate (NO3-) and phosphorous (P), cation exchange capacity (CEC), and exchangeable sodium percentage (ESP) were measured during the incubation. The EC increased in the response to the incorporation of plant residues, whereas the pH was reduced. The application of organic components in soils increased CEC and decreased ESP. The results showed that the maximum reduction in ESP was observed in the potato treatment because of the highest Ca2+ concentration. The average reduction in ESP of treated soil samples at the end of incubation followed this order: 16.1% (potato residue-treated soil) >12.7% (canola residue-treated soil) >11.1% (wheat residue-treated soil) >9.6% (sunflwer residue-treated soil). The potato residue was the most effective amendment in changing the chemical properties of saline-sodic soils in comparison with other organic residues. The results indicated that the application of organic residues had a positive impact on reducing the soil sodicity and improving the soil fertility depending on their chemical composition.</p>

Impact of Tillage and Residue Management on Hydro-physical Properties of Clay Soil under Rice-wheat Cropping System in Indo-Gangetic Plains of India

A field experiment on the residual impact of tillage operations and organic residues incorporation on hydro-physical properties of clay soil under the rice-wheat cropping system in split-plot design with three replications was carried out at the experimental farm of BAU, Sabour. The treatments of tillage operations and application of organic residues, along with their interactions, significantly decreased the soil strength/compaction and consequently bulk density of the soils over control. It was confirmed by the positive and highly significant correlation of soil strength with the bulk density (r = 0.802**). The maximum decrease was noted under T3 (Mould board plough) and C6 (GM + rice husk) and their interactions. A significant decrease in clod size was observed under treatments T3 and C6 and their interactions over control. The maximum increase in stable water-stable aggregates was estimated under treatments T3 and C6 and their interactions (T3 x C6) due to an increase in porosity and decrease in compaction of the soils which led to increasing in hydraulic conductivity. This was further confirmed by a positive and highly significant correlation of hydraulic conductivity with MWD (r = 0.788**) and negatively and highly significant correlation with compaction (r = -0.646**) and BD (r = -0.846**). It was revealed that the soil moisture content showed a variable increase with variable depth and observed their maximum values in T4 (28%) and C6 (29%) treatments at 45-60 cm depth of the soils. The increase in yield of wheat grain was highest under the influence of treatments (MB) T3 and C6 (GM + rice husk) and their interaction. These observations were further confirmed by the positive and highly significant correlation of yield of wheat grain with MWD (r = 0.514*) and HC (r = 0.482*) and negative and highly significant correlation with soil strength (r = -0.649**). The most effective treatments were T3 and C6 and their interactions, while minimum improvements were noted under T1 (desi plough) and C3 (paddy straw) and their interactions.

Simultaneous determination of wettability and shrinkage in an organic residue amended loamy topsoil

Abstract In agricultural land use, organic residues such as compost, digestate, and sewage sludge are discussed as costeffective soil conditioner that may improve the water holding capacity and crop available soil moisture. The objective of this study is to determine the effect of application of digestates with different compositions in maize, sugar beet and winter wheat, compost of shrub debris and sewage sludge on shrinkage behaviour and contact angle of till-derived loamy topsoil of a Haplic Luvisol under agricultural use. Novelty is the simultaneous determination of contact angle and shrinkage of soils amended with digestates composed of different composition in maize, sugar beet and winter wheat, compost of shrub debris and sewage sludge. The results suggest that the application of organic residues impacts the air capacity, while the contact angles remained in the subcritical range between > 0° and < 90°. The relationship between CA values and moisture ratios, ϑ, during proportional shrinkage was positive and linear (r2 of 0.98) and negative during residual- and zero-shrinkage (r2 of 0.93).