Soil erosion is a critical environmental issue in Jordan, particularly due to the country’s fragile ecosystems, steep slopes, and varying climatic conditions. It poses significant threats to agricultural productivity, natural resource conservation, and land sustainability. This study aims to provide a detailed spatial assessment of soil erosion risk across Jordan and identify erosion-prone zones to support informed decision-making in land management. The Revised Universal Soil Loss Equation (RUSLE) model, integrated with Geographic Information System (GIS) tools, was employed to estimate soil loss and map erosion severity. The model incorporated essential factors including rainfall erosivity, soil erodibility, slope length and steepness, vegetation cover, and conservation practices. Erosion rates were categorized into three classes: low (0–10 tons ha-1 year-1), moderate (10–50 tons ha-1 year-1), and high (>50 tons ha-1 year-1). Results revealed that 94% of Jordan’s land is subject to low erosion risk, 5% to moderate risk, and approximately 1% to high risk. The areas most vulnerable to erosion are located in the northern and central highlands and parts of the Jordan Valley, primarily due to their steep topography and higher precipitation levels. This study demonstrates the effectiveness of integrating RUSLE with GIS to identify critical erosion hotspots and inform targeted soil conservation strategies, contributing to more sustainable land use planning in arid and semi-arid regions like Jordan.
The Haber-Bosch (H-B) process, which enables the industrial production of ammonia from nitrogen and hydrogen, fundamentally changed food production. This process is crucial for synthesizing nitrogen-based fertilizers, which are essential for boosting crop yields and supporting the world's growing population. Monoculture farming, particularly when combined with high nitrogen input, poses significant environmental risks. It leads to soil degradation, increased vulnerability to pests and diseases, and water pollution. Reliance on synthetic fertilizers to offset nutrient depletion further worsens these problems. The question explores whether current analytical methods adequately identify and evaluate the side effects of urease (UI), nitrification (NI), and denitrification (DI) inhibitors used in nitrogen management strategies for high-yield monoculture farming. While inhibitors are designed to improve nitrogen use efficiency and reduce losses, their effectiveness must be weighed against their unintended consequences, necessitating the development of more comprehensive and holistic analytical approaches that better balance productivity and environmental protection. This research focuses on how different nitrogen fertilizer strategies, along with pesticide use, affect non-target organisms in ecosystems. It specifically examines the impacts of urea, nitrate manipulation, and stabilized nitrogen fertilizers like urease inhibitors (UI), nitrification inhibitors (NI), and dual inhibitors (DI) on ecological balance. The study also examines the broader environmental implications of these practices, including nitrogen loss and greenhouse gas emissions. It highlights how these agrochemicals can affect wild plants, pollinators, and other non-target species, potentially disrupting ecosystem functions.
Indonesia’s national agriculture production is increasingly constrained by the expansion of marginal lands with low productivity, many of which have undergone severe degradation from mining and other land uses. These lands are characterized by low soil fertility and acidic pH, posing a challenge for sustainable forage production. This study investigates the application of pre-Terra Preta - a soil amendment composed of biochar, organic matter, animal manure, topsoil, and fermented microorganisms—to enhance the productivity of marginal land, using Pennisetum purpureum cv. Mott (Dwarf elephant grass) as a forage crop. The field experiment was conducted in Swarangan Village, Tanah Laut Regency, South Kalimantan, Indonesia. Soil chemical properties were analyzed before and after planting. A total of 36 plots (5 × 5 m) were treated with four levels of pre-Terra Preta biochar composition (0%, 20%, 40%, and 60%) and three application rates (10, 20, and 30 t ha⁻¹). The results showed significant improvements in soil chemical properties, including total N (↑ 73.47%), organic C (↑ 35.20%), K₂O (↑ 33.64%), and pH (↑ 148.89%). The optimal treatment—30 t ha⁻¹ with 60% biochar—yielded the highest plant height (16.875 cm), number of leaves (12.900), and number of tillers (3.791). These differences were significant (p < 0.05), confirming the effectiveness of both biochar levels and application rates. Pre-Terra Preta offers a sustainable, cost-effective strategy for rehabilitating marginal lands in tropical regions. Further studies are recommended to assess long-term soil health, economic viability, forage quality, and livestock performance.
Lemon trees require the nutrients they extract from the soil. This research aims to analyze the impact of organic matter application on enhancing soil nutrient availability and improving soil chemical properties using a pot-scale incubation experiment. This study used a completely randomized design with eight treatments and four replications. The pot treatment used 10 kg of air-dry soil per pot mixed with an organic matter dosage of 30 tons ha-1 and was observed at 2, 4, 8 weeks after applications. The treatment consisted of P1 (topsoil, control), P2 (subsoil, control), P3 (topsoil + compost), P4 (subsoil + compost), P5 (topsoil + cow manure), P6 (subsoil + cow manure), P7 (topsoil + goat manure), and P8 (subsoil + goat manure). The results indicated that compost and manure fertilizer had a significant effect in increasing soil chemical properties (pH, organic carbon content, cation exchange capacity, total-N, available-P, and exchangeable-K), with topsoil treatment having the highest value compared to the subsoil treatment, almost at all parameters. The topsoil treatment + 30 tons ha⁻¹ cow manure significantly increased the N-total by 44.44% at 8 and 12 WAA on the control treatment. The topsoil treatment + goat manure 30 tons ha-1 significantly increased P-available by 13.63 - 29.74% and exchangeable-K by 40.61 - 62.88% at 4, 8, and 12 WAA against the control treatment. Based on these findings, the best fertilizer method of topsoil treatment + 30 tons ha⁻¹ of manure is recommended to increase the soil fertility of the lemon tree soil.
Cotton yield in Bangladesh is often constrained by suboptimal planting times under subtropical conditions. The present study aimed to evaluate the impact of planting dates on seed cotton yield across four cultivars to identify the optimal timing for profitable production. A three replicated field trial was conducted at the Cotton Research Farm in Gazipur using split-plot design during the cotton growing season of 2022-23. Four cotton cultivars: DM-3, Rupali-1, Suvra, and CB-12 were planted on five dates at ~15-day intervals from June to August (viz: 5 June, 20 June, 5 July, 20 July, and 5 August). Results showed that planting on 20 July significantly increased seed cotton yield by 2.580 t ha⁻¹ compared to 5 June, while the 5 August planting produced the lowest yield and ginning outturn (8.9%) (P < 0.01). Among cultivars, CB-12 achieved the highest yield (2.14 t ha⁻¹), followed by Rupali-1 (1.93 t ha⁻¹) and DM-3 (1.56 t ha⁻¹). Although no significant interaction was observed between planting date and cultivar, CB-12 consistently performed best on 20 July, with similar trends for the other cultivars. The study emphasizes the significance of choosing the most suitable planting dates and cultivars. Adoption of 20 July as the ideal planting date may enhance productivity, offering valuable guidance for cotton growers, researchers, and policymakers.
The contamination of antibiotics in water bodies has increased significantly in recent years. Various treatments, including adsorption, have been sought, but most include expensive sorbent material with low efficiency. This research reported an alternative sorbent material; synthetic zeolite derived from coal-burning waste. Coal bottom ash was converted to zeolite via a hydrothermal technique using various concentrations of NaOH and relatively low-temperature conditions. X-ray diffractogram confirms the formation of ZSM-23 when a 1:2 coal-to-zeolite ratio was used at 95°C. The FTIR spectra also highlighted the characteristics of zeolite functional groups, such as the Si−O vibration at 999.56 cm-1 and the Al−O vibration at 799.48 cm-1. The needle-like morphology of ZSM-23 was observed during SEM-EDS analysis. When calculated using BET analysis, the synthetic zeolite also exhibited a high surface area of 433.517 m2 g-1. Upon application in a batch experiment, the maximum adsorption capacity of the zeolite for amoxicillin (AMX) adsorption in aqueous solution was found to be 673.5 mg g-1. The adsorption data fitted the Langmuir isotherm better than the Freundlich one, with a correlation factor of 0.9328. This suggested the monolayer interaction, possibly between the negatively charged zeolite surface and the NH3+ group from AMX. However, the physical adsorption mechanism with the zeolite surface may also occur due to the high surface area. Considering the low production cost, this zeolite offers high economic value as an alternative sorbent for removing antibiotics in water effluent.
To boost phosphorus (P) availability in soils, adding organic matter like compost, manure, or vermicompost (VC) is a sustainable solution. A field experiment investigated how VC and phosphatic fertilizers affect P bioavailability, plant uptake, and yield response of BARI Soybean-5. Eight treatments i.e., T1 = control (no P), T2 = 100% recommended dose of P (RDP) from triple superphosphate (TSP), T3 = 100% RDP from diammonium phosphate (DAP), T4 = 100% RDP from VC, T5 = 75% RDP from TSP + 25% from VC, T6 = 75% RDP from DAP + 25% from VC, T7 = 50% RDP from TSP + 50% from VC, and T8 = 50% RDP from DAP + 50% from VC were replicated thrice on randomized complete block design (RCBD). T2 treatment generated a maximum seed yield of soybean (1.66 t ha-1), exceeding T3, T5, T6, T7, and T8 treatments with 1.63, 1.54, 1.52, 1.50, and 1.50 t ha-1, respectively. Also, T2 performed the highest P contents in seed, root, and straw (1.27, 0.19, and 0.41%, respectively) and total uptake of P (28.15 kg ha-1) among the treatments. T4 exhibited significantly higher levels of organic C, total N, available P, exchangeable K, and available S. Overall findings revealed that growing BARI Soybean-5 with 100% RDP from TSP (T2) proved a good practice for yield response, but 100% RDP from VC (T4) would be preferable for long-term soil health. This study would be helpful for choosing organic or inorganic sources of P fertilizers for soybean production.
Soil microbial populations and activities have been repeatedly reported to be severely affected by high concentrations of heavy metals. However, little of this information comes from tropical soil. The fungal and bacterial populations in tropical soils contaminated with heavy metals were observed in a laboratory study. Soils that have been amended once with different rates of heavy-metal-containing waste (0-60 Mg ha-1) in 1998 (23 years ago) were used in this study. We then treated the contaminated soils with different rates of biochar (0-10 Mg ha-1). Biochar is known to significantly reduce heavy metal contaminants through various immobilization reactions. The soil-biochar mixtures were allowed to equilibrate at the soil field water capacity, maintained by a common water reservoir beneath the soil-biochar mixtures, for 4 weeks. After this period, the soil fungal and bacterial populations were counted. The results of the present study showed that high soil levels of Cu and Zn significantly enhanced the fungal population. In contrast, the bacterial population was not affected by the presence of Cu and Zn. In the highly contaminated pots, the addition of biochar significantly enhanced the population of soil fungi (identified as Aspergillus sp.), but it did not affect the population of bacteria. The results of the study suggest that biochar application led to significant enhancement of the population of Aspergillus sp. in pots with high soil Cu and Zn levels, most likely through improved habitat conditions provided by biochar’s porous structure, which could be leveraged in bioremediation efforts for heavy metal-contaminated soils.
Heavy metal absorption by plants is suggested to be affected by soil treatment with different types of biochar. Due to various types of available biochar materials in the environment, effects of three representative biochar types were evaluated in a greenhouse experiment using polluted soils planted with pigweed (Amaranthus spinosus L.) and napier grass (Pennisetum purpureum Schumach). Soil treatments were conducted with biochar of rice (Oryza sativa)-husk, corn (Zea mays)-cob and cassava (Manihot utilissima)-stem at 10 Mg ha-1. Soils and plants were analysed for Cu and Zn after a 4 weeks plant growth. The results showed that Cu and Zn accumulation by pigweed and napier grass were higher in soils polluted with more Cu and Zn. Pigweed in general acted as phytoextractor, accumulated more Cu and Zn in shoots, while napier grass as phyto-stabilizer, accumulated more Cu and Zn in roots. Pigweed accumulated Cu more effective than napier grass while napier grass more effective in Zn accumulation. Unlike rice-husk or corn-cob, cassava-stem biochar increased the soil Cu and Zn concentrations. Rice-husk and corn-cob enhanced but cassava-stem biochar decreased Cu and Zn accumulation by pigweed and napier grass. Rice-husk and corn-cob biochar showed better potential than cassava biochar for soil Cu and Zn phytoremediation by pigweed and napier grass in heavy-metal polluted tropical soils.
The agricultural sector faces dual challenges of declining soil fertility and unsustainable waste accumulation. This study examines the synergistic effects of fly ash (FA) and plant growth-promoting bacteria (PGPB) on the growth and physiological performance of maize (Zea mays L.) under controlled (potted) conditions. FA, a coal combustion by-product rich in essential minerals, was applied at varying doses (1–4 t ha-1) to assess its potential as a soil amendment with a bacterial strain (BSNK7) inoculated to enhance nutrient uptake and mitigate stress. Results showed a significant increase in fresh and dry biomass, leaf area, and chlorophyll content in treated plants. The combined application of 1 t ha-1 FA in conjunction with PGPB significantly increased fresh biomass by 1.57%, dry biomass by 0.94%, leaf area by 2.21%, and higher chlorophyll content compared to control (FA 0 t ha-1 and without bacteria). In contrast, FA 4 t ha-1, when applied without bacterial inoculation, resulted in reduced fresh biomass by 19.94% and dry biomass by 17.39%, respectively, compared to the control (FA 0 t ha-1 and without bacteria) which indicates the creation of toxicity at elevated doses. These findings suggest that the integrated use of low-dose FA and PGPB can sustainably enhance maize growth while minimizing environmental risks. The Application of appropriate doses of FA with PGPB can increase crop productivity and soil health simultaneously. Further field-based studies are recommended to validate scalability, optimize application rates, and assess the long-term impacts on soil health impacts.
The response of soil structure to nutrient management may vary across environments. Poultry manure (PM) and/or inorganic fertilizers (IF) effects on soil pH, organic carbon (SOC), and hydraulic properties were assessed in derived savannah sandy-clay-loam Ultisols and rainforest sandy-loam Alfisols of Nigeria during 2013-2015. The Ultisols were inherently lower in soil pH and SOC than the Alfisols. Three PM rates (0, 5, and 10 t ha–1), each with four NPK/Urea-based IF levels (0, 50, 100, and 150%), were applied in 2013 and 2014 but not in 2015. At crop (maize) maturity, treatment affected the Ultisols more distinctly than the Alfisols. Regardless of IF level, PM10 and PM5 resulted in optimal soil pH (Ultisols) and hydraulic properties (Alfisols), respectively. Treatment PM10+IF50 produced overall optimal effects in 2014 and 2015, being among the highest for SOC in the Ultisols (13.30 and 10.23 g kg–1, respectively) and Alfisols (16.10 and 11.60 g kg–1, respectively). Its substitutes for soil pH and hydraulic properties were PM10+IF0 (Ultisols) and PM5+IF0 (Alfisols). Unlike most PM-based treatments, sole IFs, especially PM0+IF150, had pronounced soil-acidifying effects in the Ultisols. The SOC and permeability depended almost entirely on PM across IF levels. Soil pH and SOC were positively correlated with total porosity (Ultisols) and permeability (both soils), with r = 0.60-0.93 (Ultisols) and 0.42-0.66 (Alfisols). Effective PM+IF may not always outperform PM regarding soil pH/SOC, whose influence on soil hydraulic properties can be location-specific. This calls for pre-adoption validation of promising PM+IF options in new tropical agro-environments.
Water supply is one of the determining factors for successful production during tomato cultivation. Many farmers still carry out vegetable seedling activities using polybags and provide water daily. This research aims to find out whether this potting compost can store water well to be an alternative to polybags as a planting medium. Pot compost with tapioca adhesive has good water absorption and storage capabilities, which can help increase water storage capacity, reducing the need for irrigation water. This research uses a descriptive analysis method with the parameters measured including vegetative growth, length and width of cracks in compost pot, and compost weight before and after watering. The vegetative observations of tomato plants showed that treatment T1 had better growth than treatments T2 and T3 in plant height which averaged 56.40 mm and an average number of leaves of 5.20 strands on day 14. However, treatment T2 had better shape resistance than treatment T1 which only had an average crack length of 25 mm and an average crack width of 2.20 mm. In observations of measuring the water holding capacity of pot compost, treatment T3 was found to be the most optimal in storing water because on day 6 it still stored 12 ml of water compared to treatments T2 and T1. If this research is applied to large-scale plant nurseries, it can reduce plastic waste originating from polybags.
Agriculture remains a cornerstone of economic development, food security, and the livelihoods of rural communities in sub-Saharan Africa. This study employed a parametric evaluation approach to assess the suitability of soils in the Nsukka Local Government Area (LGA) of Enugu State, Southeastern Nigeria, for cultivating maize (Zea mays) and Cassava (Manihot esculenta) using the Geographical Information System (GIS). The study applied the FAO land evaluation framework using systematic soil sampling, laboratory analyses, and GIS mapping. A total of thirty geo-referenced soil samples from the surface (0-20 cm) were gathered in triplicate across Nsukka LGA. Climatic and topographic data were integrated with soil parameters to assess suitability. Thematic maps were developed and overlaid to generate suitability classes for maize and cassava using the ArcGIS software. The climate characteristics were highly suitable for crop production. Topography (slope) and soil characteristics (texture, organic carbon, and base saturation) were the most limiting factors for both crops. The maps showed that 6.18% of the study region was highly suitable, while 93.82% was moderately suitable for maize production. The study region was entirely suitable for cassava cultivation. These results support the recommendation for crop-specific land-use planning and targeted soil management practices to improve maize productivity and leverage cassava's resilience in marginal soils.
Synthetic microbial communities (SynCom) present a promising strategy for sustainably enhancing agricultural productivity and ecological resilience. This review critically discusses recent advancements in applying SynCom within agricultural ecosystems and highlights their practical benefits for economic sustainability. Plant growth-promoting (PGP) traits are essential for developing SynCom, as they enhance plant growth, increase nutrient uptake, improve stress tolerance, and support resistance to pathogens. SynCom demonstrates significant effectiveness as a biofertilizer, substantially improving soil health and crop yields through enhanced nutrient cycling and bioavailability. Its role as a biopesticide is also significant, as it offers an eco-friendly approach to insect pest management. The integration of SynCom into agricultural practices has proven to enhance plant disease resistance, significantly contributing to crop resilience. Moreover, SynCom plays a vital role in maintaining soil fertility, promoting carbon sequestration, and mitigating the impacts of climate change. Its applications extend to environmental remediation, where it effectively degrades hazardous pollutants in agricultural soils and efficiently processes lignocellulosic biomass, supporting sustainable biomass utilization. SynCom offers considerable advantages but also faces challenges, including community stability, environmental adaptability, and regulatory concerns. Future research efforts aim to address these limitations and enhance SynCom's efficacy regarding long-term agricultural sustainability. Our review provides valuable insights for policymakers, practitioners, and researchers to construct SynCom-based strategies that promote plant growth, enhance sustainable agriculture, and support environmental conservation.
Soil salinity represents a major constraint to agricultural productivity in arid and semi-arid regions, severely affecting cereal growth and yield. This study evaluated the effect of mineral soil amendments using two types of bentonite, sodium bentonite from Mostaganem (B-Na) and calcium bentonite from Maghnia (B-Ca), on the morphological, physiological, and biochemical responses of durum wheat Triticum durum Desf. And bread wheat Triticum aestivum L. cultivated in saline soil 19 dS.m⁻¹ from the Relizane region (western Algeria). Greenhouse experiments were conducted using bentonite doses of 5% and 10% (w/w) to assess plant growth parameters, relative water content (RWC), chlorophyll pigments, and soluble sugar levels. Both bentonites enhanced wheat performance under saline conditions, with the 5% dose producing the most favourable effects. Notably, 5% B-Na significantly increased RWC, chlorophyll concentration, and soluble sugar content in T. aestivum compared with the saline control. Excessive amendment (10%) did not yield further benefits. These findings suggest that moderate application of bentonite can effectively alleviate salinity stress and improve physiological performance in wheat. The study emphasizes the importance of optimizing bentonite type and dose based on soil characteristics and crop sensitivity to salinity.
Overuse of traditional chemical fertilizers may result in environmental pollution and a decrease in the quality of farm produce. By contrast, applying biochar-organic compound fertilizers can enhance soil structure, increase soil fertility, and mitigate pollution levels. This study explores the intricate mechanisms of the combined application of biochar-organic compound fertilizers and chemical fertilizers on soil chemical properties and corn growth. The aim is to elucidate the theoretical foundations supporting the widespread adoption of biochar-organic compound fertilizers. A total of 6 treatments were set up, among which the CK treatment did not apply fertilizer, the CF treatment used bovine excrement organic fertilizer combined with chemical fertilizer, the T1 to T4 treatments used biochar-organic compound fertilizers and replaced 40%, 60%, 80%, and 100% bovine excrement organic fertilizer combined with chemical fertilizer. The results showed that applying biochar-organic compound fertilizers enhanced the slow-release properties of soil available nutrients, increased corn yield, and improved grain quality. Notably, when biochar-organic compound fertilizers were employed instead of 100% bovine excrement organic fertilizer, the yield surpassed that of other treatments, exhibiting a remarkable 9.30% increase compared to the CF treatment. Through comprehensive analysis, it was determined that using biochar-organic compound fertilizer to replace 60% of bovine excrement organic fertilizer is a scheme that can balance both fertilizer efficacy and cost and is recommended to farmers. This research can contribute to promoting the green transformation of agriculture and help achieve the goal of "carbon neutrality".
Agricultural waste management remains a critical environmental concern, necessitating sustainable approaches to transform organic residues into valuable resources. Among these, composting offers an effective solution by converting biomass into nutrient-rich soil amendments and reducing the burden of waste disposal. This study aims to investigate the potential of combined agricultural waste composting for producing high-quality compost and enhancing soil properties in a coffee plantation. Eight composting treatments and three replications were formulated: P1: Saccharum officinarum leaves (100%), P2: Coffee pulp (100%), P3: Gliricidia sp. leaves (100%), P4: Saccharum officinarum leaves (50%) + Coffee pulp (25%) + Gliricidia sp. leaves (25%), P5: Coffee pulp (50%) + Saccharum officinarum leaves (25%) + Gliricidia sp. leaves (25%), P6: Gliricidia sp. leaves (50%) + Coffee pulp (25%) + Saccharum officinarum leaves (25%), P7: Coffee pulp (50%) + Saccharum officinarum leaves (50%), and P8: Coffee pulp (50%) + Gliricidia sp. leaves (50%). The findings indicated that the compost mixtures containing Gliricidia sp. leaves and coffee pulp yielded a C:N ratio of less than 25, signifying that the compost was mature. The application of compost resulted in an overall increase in soil pH, organic carbon, and total nitrogen, while also ameliorating soil structure through reduced bulk density and enhanced porosity, particularly at a depth of 30–60 cm. These results provide valuable insights for farmers and agricultural policymakers in developing sustainable waste management strategies that effectively address agricultural waste disposal challenges while improving soil fertility and promoting more environmentally friendly coffee production systems.
The increasing demand for maize in Indonesia is challenged by suboptimal productivity on acidic Ultisols, despite high doses of inorganic fertilizers being applied. This study aimed to evaluate soil pH dynamics and maize response to liquid organic fertilizer (LOF) enriched with Sapindus rarak biosurfactants as a substitute for chemical fertilizers. A factorial completely randomized design was used with two factors: inorganic fertilizer (NPK + Urea) doses (0%, 50%, and 100% of the recommended rate) and biosurfactant concentrations (0%, 0.1%, 0.2%, and 0.3%). Data were analysed using the F-test at a 5% significance level, with LSD tests applied for significant effects. Results showed that soil pH in maize crops decreased over time but remained slightly acidic. Higher NPK doses generally increased soil pH, especially at 45 days after planting (DAP). Biosurfactant-enriched LOF significantly impacted leaf area index (LAI), relative growth rate (RGR), and shoot-root ratio, particularly at 60 DAP. The highest maize yield, reaching 6.60 tons per hectare, was obtained with a combination of 50% of the recommended inorganic fertilizer and 50 mL L⁻¹ of 0.1% biosurfactant-enriched LOF. This yield is comparable to the normal yield obtained by farmers when applying 100% of the recommended rate of inorganic fertilizer. Optimising fertilizer application and planting strategies to effectively manage the shoot-to-root ratio is essential for improving maize productivity and enhancing resource use efficiency. The study highlights the potential to reduce chemical fertilizer use by up to 50%, lowering costs while improving soil pH and root development. It promotes efficient resource use, supports integrated nutrient management using local materials such as Sapindus rarak, and encourages farmer training and sustainable agricultural policies to restore productivity on degraded Ultisols.
Nitrogen (N) is the most essential nutrient element for improving crop yield. However, urea, its most common form, is highly prone to losses, especially in flooded rice fields, which reduces N use efficiency (NUE) and contributes to environmental degradation. Here, a field experiment was conducted to examine the yield and growth performance of Aman rice, as well as to estimate NUE using different organic amendments and inorganic N sources. The treatments consisted of two factors: a) organic amendments- waste biochar, sawdust biochar, cow dung, and control, and b) N application rate- control (0), 50%, and 100% of the recommended rate. Overall, waste biochar performed better than sawdust and cow dung. Waste biochar with 100% of the recommended rate of urea application provided the highest grain (4.65 t ha-1) and straw yield (6.72 t ha-1). However, waste biochar with 50% recommended urea application provided the best NUE, i.e., agronomic N use efficiency (46 kg rice grain kg-1 N applied), physiological N use efficiency (28 kg rice grain kg-1 N uptake), and apparent N recovery (61%). The relatively higher NUE in treatments with organic amendments and half the recommended N rate; suggests a trade-off between improved NUE and rice grain yield. The enhanced NUE was possibly manifested by retaining more N in the reactive sites of soil organic matter and its uptake in the plant. Altogether, our results provide insights into NUE in rice cultivation systems after application of diverse organic matters.
Identifying the start of sowing in rice fallows is challenging due to its typical low land agro-ecosystem. Tracking the spatio-temporal shifts that take place during the transition from a wet to dry ecosystem, identifying crops, assessing their extent, and identifying optimal planting periods are vital information for researchers and planners. This study aimed at determining the crop sown area and sowing window of maize and sorghum crops planted in rice fallows during the Rabi 2020-2021 season in the Krishna Western delta of Guntur district, Andhra Pradesh. Optical cloud-free satellite images of Landsat-8 and Sentinel-2 were downloaded and using band ratios NDVI and NDWI was derived. A Threshold based algorithm was developed to detect the crop sowing window. The total area sown was determined using the SVM algorithm. The threshold-based algorithm is well-suited for identifying the sowing windows. The sowing window in the second fortnight of January had the largest area for both crops compared to other sowing windows. The detected sowing windows exhibited a deviation of up to two satellite acquisition intervals. The estimated area using SVM algorithm for maize and sorghum was 29,518 ha and 65,417 ha, respectively. The threshold-based algorithm overestimated the maize and sorghum crops as compared to SVM. This study established the superior performance of the Support Vector Machine (SVM) algorithm for crop classification. Statistical validation confirmed that the SVM model achieved significantly higher accuracy in distinguishing both maize and sorghum from other land covers compared to the threshold-based algorithm, which exhibited a greater tendency for misclassification.
