Agricultural Soil Fertility Research Articles

Response of soil carbon and nitrogen stocks to irrigation - A global meta-analysis

Irrigation has profound influences on carbon (C) and nitrogen (N) stocks in agricultural soil. However, the global-scale irrigation effects on C and N pools in farmland soils, as well as the C: N ratio (C/N), remain unclear. This study integrates existing studies on C and N in irrigated farmland worldwide and investigates the responses of soil C and N concentrations, stocks, and the C/N to irrigation by meta-analysis. The results suggest that irrigation has a significantly positive impact on soil organic carbon (SOC) and total nitrogen (TN) stocks overall, with the stocks increase by 10.9 % and 7.4 %, respectively, and a 3.1 % increase in the C/N, but has no significant impact in soil microbial biomass carbon (MBC). The positive feedback of SOC (6.0 %) and TN (6.6 %) stocks in topsoil is more pronounced in response to irrigation than that in subsoil. The impact of irrigation on SOC stocks is greater in semi-arid regions and under flood irrigation. Furthermore, SOC stocks increase more in sandy and loamy soils compared to clay soil, while TN exhibits larger increases in clay soil. The results also indicate that the response of C/N to irrigation is more pronounced under the condition of deep soil, sandy soil, and semi-arid regions. The influence of irrigation on SOC stocks and the C/N increases with the duration of irrigation, while the impact on TN stocks tends to weaken. Our study deepens the understanding of the mechanisms behind irrigation's effects on soil C and N stocks and therefore provides theoretical insights for the management of soil fertility in irrigated agriculture.

Position-specific kinetic isotope effects for nitrous oxide: a new expansion of the Rayleigh model

Abstract. Nitrous oxide (N2O) is a potent greenhouse gas and the most significant anthropogenic ozone-depleting substance currently being emitted. A major source of anthropogenic N2O emissions is the microbial conversion of fixed nitrogen species from fertilizers in agricultural soils. Thus, understanding the enzymatic mechanisms by which microbes produce N2O has environmental significance. Measurement of the 15N / 14N isotope ratios of N2O produced by purified enzymes or axenic microbial cultures is a promising technique for studying N2O biosynthesis. Typically, N2O-producing enzymes combine nitrogen atoms from two identical substrate molecules (NO or NH2OH). Position-specific isotope analysis of the central (Nα) and outer (Nβ) nitrogen atoms in N2O enables the determination of the individual kinetic isotope effects (KIEs) for Nα and Nβ, providing mechanistic insight into the incorporation of each nitrogen atom. Previously, position-specific KIEs (and fractionation factors) were quantified using the Rayleigh distillation equation, i.e., via linear regression of δ15Nα or δ15Nβ against [-fln⁡f/(1-f)], where f is the fraction of substrate remaining in a closed system. This approach, however, is inaccurate for Nα and Nβ because it does not account for fractionation at Nα affecting the isotopic composition of substrate available for incorporation into the β position (and vice versa). Therefore, we developed a new expansion of the Rayleigh model that includes specific terms for fractionation at the individual N2O nitrogen atoms. By applying this Expanded Rayleigh model to a variety of simulated N2O synthesis reactions with different combinations of normal, inverse, and/or no KIEs at Nα and Nβ, we demonstrate that our new model is both accurate and robust. We also applied this new model to two previously published datasets describing N2O production from NH2OH oxidation in a methanotroph culture (Methylosinus trichosporium) and N2O production from NO by a purified Histoplasma capsulatum (fungal) P450 NOR, demonstrating that the Expanded Rayleigh model is a useful tool in calculating position-specific fractionation for N2O synthesis.

Bacterial bioaugmentation for paracetamol removal from water and sewage sludge. Genomic approaches to elucidate biodegradation pathway

Wastewater treatment plants (WWTPs) are recognized as significant contributors of paracetamol (APAP) into the environment due to their limited ability to degrade it. This study used a bioaugmentation strategy with Pseudomonas extremaustralis CSW01 and Stutzerimonas stutzeri CSW02 to achieve APAP biodegradation in solution in wide ranges of temperature (10–40 °C) and pH (5−9), reaching DT50 values < 1.5 h to degrade 500 mg L−1 APAP. Bacterial strains also mineralized APAP in solution (<30 %), but when forming consortia with Mycolicibacterium aubagnense HPB1.1, mineralization significantly increased (up to 74 % and 58 % for CSW01 +HPB1.1 and CSW02 +HPB1.1, respectively), decreasing DT50 values to only 1 and 9 days. Despite the complete degradation of APAP and its high mineralization, residual toxicity throughout the process was observed. Three APAP metabolites were identified (4-aminophenol, hydroquinone and trans-2-hexenoic acid) that quickly disappeared, but residual toxicity remained, indicating the presence of other non-detected intermediates. CSW01 and CSW02 degraded also 100 % APAP (50 mg kg−1) adsorbed on sewage sludge, with DT50 values of only 0.7 and 0.3 days, respectively, but < 15 % APAP was mineralized. A genome-based analysis of CSW01 and CSW02 revealed that amidases, deaminases, hydroxylases, and dioxygenases enzymes were involved in APAP biodegradation, and a possible metabolic pathway was proposed.

Towards a national model of humus (carbon) budget management in soils of agroecosystems in the Russian Federation

The prospect of adapting two methods for monitoring the fertility of agricultural soils (humus balance, HB) under spring and winter wheat crops (hereinafter referred to as grain crops) developed in the Russian Federation (RF) for the purposes of climate projects has been studied. It was revealed that the RosNIIzemproekt method (1998) underestimates the HB average value to -7.7 c/ha for RF. The RosNIIzemproekt method (1998) has logical errors in the calculation model and is not recommended for use. The TsINAO method (2000) has a more logical calculation model. According to this method, the average value of HB in soils for RF is generally positive and amounts to 3.3 c/ha (0.71 tCO2-eq/ha carbon units). This value constitutes ≈0.3% of average humus reserves in arable soils of the RF (108 tС/ha). The annual value of change in humus content under spring and winter wheat is incommensurably less than the total humus reserves in the soil. Statistically reliable assessment of changes in humus content requires a huge number of soil samples. This makes the verification procedure economically inexpedient. Another option is proposed to increase the time of humus accumulation. It is considered (IPCC, 2003) that a 20-year accumulation period is sufficient, which corresponds to the duration of soil climate projects. A coefficient (0.216) has been proposed for converting humus reserves (c/ha) to the value of a carbon unit (tCO2-eq/ha). The total sequestration of carbon by soils under grain crops in 2022 was about 11 million 914 thousand tCO2-eq. HB accounting significantly compensates for calculated emissions from agricultural production and reduces them by almost 10% (from 116 to 105 million tons CO2-eq in 2022). For both models of fertility monitoring, an assessment was made of the quality of the regression dependence of HB on the total biomass of photosynthesis (TBP) in soils under grain crops. It is shown that according to Fisher's t-test at a 5% significance level, the studied relationship is significant and characterized by the squares of the correlation coefficient (R2) equal to 0.554 and 0.998. In accordance with the Chaddock scale, the closeness of the correlative relationship between HB and TPB for winter wheat is assessed as high, and for spring wheat as very high.

Nanoagrochemicals versus Conventional Fertilizers: A Field Case Study with Tailor-Made Nanofertilizers for Sustainable Crop Efficiency of Brassica oleracea L. convar. Capitata var. Sabauda

Excessive use of conventional fertilizers in agricultural soils can lead to environmental contamination, particularly affecting aquifers and surface waters. Nanofertilizers, with smaller particles and greater nutrient efficiency, offer a promising alternative. This study evaluates the application of nanofertilizers by reducing NPK-doses compared to conventional fertilizers in the cultivation of Brassica oleracea L. convar. capitata var. sabauda (Savoy cabbage). Field assays were conducted in experimental plots with different NPK doses and treatments using urea-hydroxyapatite and potassium sulfate nanoparticles (optimum dose: 80 N, 100 P2O5, 250 K2O kg ha−1; and half optimum dosage). The assay was monitored throughout the crop cycle, and cabbages were harvested to determine biometric parameters, yield, and nutrient contents. The results indicated that nanofertilizers at half the recommended dosage yielded similar results to conventional fertilization in terms of cabbage growth and yield. Specifically, soil pH and available P increased by the end of the crop cycle, while total N, C, CEC, and soil texture remained unchanged, regardless of the fertilizer dose applied. Cabbage plants treated with nanofertilizers showed no significant differences in nutrient content compared to those treated with conventional fertilizers. This study supports the potential of nanofertilizers as an environmentally sustainable alternative that can reduce nutrient inputs in agriculture without compromising crop yield and quality.

Soil erosion risk assessment of the Lakhmess watershed (northwestern Tunisia) via the SEAGIS model: Inferred prioritization of risky sub-watersheds

Water erosion in Tunisian semi-arid regions causes harmful effects by silting reservoirs and reducing agricultural lands and soil fertility. Several factors are involved in the erosion process: rain erosivity, soil fragility, and degraded land cover on steep slopes associated with the intensification of inappropriate human practices. Thus, identifying erosion vulnerable sub-watersheds based on the assessed soil loss rate is very important to apply suitable conservation measures. The current research aimed to prioritize risky areas in the Lakhmess watershed, north-west Tunisia via the Soil Erosion Assessment using Geographical Information System (SEAGIS) model. To prioritize sub-watersheds vulnerable to soil erosion and sediment yield, the Lakhmess watershed, covering an area of 162 km2, was divided into 16 sub-watersheds (L1–L16), according to the hydrographic network. Then, the mean annual soil erosion rate and the mean annual sediment yield in the watershed were estimated by integrating the Revised Universal Soil Loss Equation (RUSLE) and the Sediment Delivery Ratio (SDR) in the SEAGIS model and their spatial distribution was determined. The obtained results indicate that the estimated average annual soil erosion rate is 4.2 t/ha/y and the annual sediment yield is 2.6 t/ha/y. Maner's SDR model was selected as the best model for estimating SY, with standard error, standard deviation, and coefficient of variation values of 0.75%, 0.01, and 0.45%, respectively. The prioritization of the Lakhmess sub-watersheds based on the estimated soil loss rate reveals that among the 16 sub-watersheds, three sub-watersheds (L10, L12, and L15) were identified as being in a very high priority soil erosion class. The high soil erosion rate and sediment yield in these sub-watersheds is explained by the steep slope and a high rainfall erosivity factor. Six sub-watersheds (L2, L4, L5, L6, L7, and L16) were found to belong to a very low priority soil erosion class, as they are characterized by a very gentle slope, which appears to be an extremely determining factor. These findings constitute a basis for decision makers to plan effective conservation measures to conserve agricultural lands, soil, and water resources in northwestern Tunisia.

Sand mining deteriorates soil fertility and farming livelihoods around Accra, Ghana

Urbanization in Sub-Saharan Africa requires vast quantities of sand to meet infrastructural demands. In Accra, Ghana, sand mining occurs predominantly on farmlands at the city’s periphery. We selected three study communities to assess the effects of sand mining on agriculture using interviews with local farmers and soil analyses of mined and unmined fields. The results underscore the profound repercussions of sand mining on farmers, characterized by substantial agricultural land loss, the destruction of food crops, and the absence of compensation payments or land reclamation. The study further reveals a significant decline in soil fertility of mined fields compared to unmined fields as evidenced by reduced levels of carbon (C, by 6.3 g kg-1) and macronutrients (nitrogen (N, by 0.6 g kg-1), phosphorus (P, 12.7 mg kg-1), potassium (K, 77 mg kg-1) and magnesium (Mg, 88 mg kg-1)), and an increase in soil compaction (bulk density by 0.13 g cm-3 and penetration resistance by 0.11 MPa). Soil texture and pH were altered and sodium (Na, by 16 mg kg-1) and soil moisture (by 4%) increased. On a communal level, sand mining adversely affected water availability, road infrastructure, and the health of residents. The study fills research gaps on the effects of sand mining on agricultural productivity, soil fertility and livelihoods, emphasizing the urgent need for effective regulation, law enforcement and collaboration as well as compensation and land reclamation mechanisms to limit the adverse impacts of sand mining on ecosystem services. Further, the use of more sustainable building materials should be fostered to reduce the demand for sand in Ghana.

Analyzing Soil Quality and Fertility in Agriculture: A Comprehensive Review of Regression Techniques

Analyzing Soil Quality and Fertility in Agriculture: A Comprehensive Review of Regression Techniques

Under Long-Term Agricultural Systems, the Role of Mycorrhizae in Climate Change and Food Security

Over the past 100 years, the rapid growth in population from 2 billion to 8 billion has significantly impacted the environment and climate change. In addition, food consumption has skyrocketed, and there are widespread worries about global food security. Due to inadequate soil and plant management techniques, including high soil tillage, chemical fertilizers, inappropriate irrigation, and genetically engineered crops, this spike has made it more difficult to guarantee food security for everyone on the planet. These actions have resulted in societal unrest, climatic change, and land degradation. With organic carbon mineralization, more CO2 is released into the atmosphere because of atmospheric heating and climate change. Long-term greenhouse gasses released into the atmosphere cause global climate change. Increasing climate changes and the inefficiency of soil productivity result in the natural effects of the rhizosphere on plant growth and food security. One of the most effective mechanisms of the rhizosphere is mycorrhizal fungi, which are injured microorganisms. Frequently disregarded mycorrhizal fungi present a potential solution. While sequestering carbon from the atmosphere, they can increase agricultural yields, plant health, and soil fertility. For sustainable agriculture and environmental preservation, it is essential to understand and take advantage of the potential of mycorrhizal fungi. A crucial area for study and practical application is the function of mycorrhizal fungi in reducing these difficulties and enhancing food security. Considering rising environmental challenges, understanding their contributions and researching their relationships may help create a more stable and secure global food system..

Chemical characterization of volatile organic compounds emitted by animal manure

Animal manure is considered a valuable organic fertilizer due to its important nutrient content enhancing soil fertility and plant growth in agriculture. Besides its beneficial role as fertilizer, animal manure represents a significant source of volatile organic compounds (VOCs), playing a significant role in atmospheric chemistry. Understanding the composition of VOCs Understanding VOCs from animal manure is crucial for assessing their environmental impact, as they can cause air pollution, odors, and harm to human health and ecosystems. Laboratory studies enhance field measurements by providing a precise inventory of manure emissions, addressing gaps in existing literature. Both approaches complement each other in advancing our understanding of manure emissions. In this context, we conducted an experimental study involving various animal manures (cow, horse, sheep, and goat) taken from a farm in Grignon (near Paris, France). We employed atmospheric simulation chambers within a controlled laboratory environment. The analysis of VOCs involved the combination of Proton Transfer Reaction-Quadrupole ion guide-Time-of-Flight Mass Spectrometry (PTR-QiTOF-MS) and Thermal Desorption-Gas Chromatography-Mass Spectrometry (TD-GC-MS). Using PTR-QiTOF-MS, 368 compounds were detected and quantified within the manure samples. The complementary analysis by TD-GC-MS enhanced our identification of VOCs. Our findings revealed various chemical groups of VOCs, including oxygenated compounds (e.g., ethanol, cresol, acetaldehyde, etc.), nitrogenated compounds (ammonia, trimethylamine, etc.), sulfur compounds (methanethiol, dimethyl sulfide, etc.), aromatic compounds (phenols and indoles), terpenes (isoprene, D-limonene, etc.) and halogenated compounds. Cow manure exhibited the highest VOC emission fluxes, followed by goat, sheep, and horse manures. Notably, oxygenated VOCs were dominant contributors to total VOC emission fluxes in all samples. Statistical analysis highlighted the distinct nature of cow manure emissions, characterized by oxygenated compounds and nitrogenated compounds. In addition, goat manure was isolated from the other samples with high emissions of compounds having both oxygen and nitrogen atoms in their molecular formulas (e.g., CH3NO2). The experimental dataset obtained in this study provides an inventory reference for both VOCs and their emission fluxes in animal manures. Furthermore, it highlights odorant compounds and VOCs that serve as atmospheric aerosol precursor. Future studies can explore the effectiveness of various manure treatment methods to promote sustainable agriculture practices.

Causes and Consequences of Land Degradation in Ethiopia: A Review

The term &amp;quot;land degradation&amp;quot; refers to the deterioration of the land&amp;apos;s quality and that of its surrounding components due to either natural or artificial factors. The most frequent cause of land deterioration in Ethiopia is water-induced soil erosion. Due to decreased agricultural soil fertility, land degradation has a detrimental effect on Ethiopia&amp;apos;s economy as well as agricultural production. It is now a significant issue impacting all aspect of Ethiopians&amp;apos; social, political, and economic lives. It is one of the main obstacles to the nation&amp;apos;s agricultural growth and food security. Rapid population growth, significant soil erosion, deforestation, overgrazing, insufficient vegetative cover, uneven crop production on steep slopes, erosive rainfall patterns, a lack of fallowing, and inadequate conservation measures are the main drivers of land degradation in Ethiopia&amp;apos;s highlands. The consequences of land degradation include the loss of fertile soil, which reduces the amount of land that can be used for agriculture. The state of family food security is negatively impacted by land degradation, which also directly lowers livelihoods in rural areas and has catastrophic effects on Ethiopia&amp;apos;s sociocultural context and ecological setting. Lower crop yields are the direct result of soil degradation, and agricultural households experience increased rates of poverty as a result.

Effectiveness of Soil-amended Biochar in Improving Crop Production, Soil Health and Environmental Aspects

Effectiveness of Soil-amended Biochar in Improving Crop Production, Soil Health and Environmental Aspects

OPTIMIZING ORGANIC AGRICULTURE: POULTRY MANURE DOMINATES IN ENHANCING GERMINATION AND GROWTH OF COMMON BEANS IN TANZANIA'S SEMI-ARID ENVIRONMENT

The study aimed to investigate the impact of different organic manures on the germination and growth performance of common beans (Phaseolus vulgaris L.) in Tanzania's semi arid region. Despite the widespread cultivation of common beans, limited research addresses the specific effects of diverse manure types on their germination and growth in this region. The primary objective is to assess and compare the influence of cow dung, poultry manure, rabbit manure, and a control (no manure) on common bean germination and growth. Understanding how different manure categories affect beans is crucial for optimizing agricultural practices in semi arid environments. A randomized block design was employed with four treatments (cow dung, poultry manure, rabbit manure, and control), each replicated three times. Common bean seeds were planted, and growth parameters, including plant height, leaf width, and leaf length, were measured. Data were analyzed using the Kruskal Wallis test and generalized linear models. Poultry manure consistently outperformed other categories, significantly enhancing bean germination and growth (P less than 0.05). The association between manure types and total germinated seeds was positive, with poultry and cow manures showing the most significant impact (P less than 0.05). Growth performance, especially plant height, demonstrated significant associations with manure type, plant parts' growth, time intervals, and distance from the bush. Poultry manure emerged as the most effective in promoting common bean germination and growth. The study highlights the need for tailored agricultural practices considering the diversity in manure effects. It suggests promoting organic farming practices, with an emphasis on poultry manure. Further research is encouraged to explore broader impacts on various crops. Educational initiatives are recommended to disseminate knowledge about organic manure benefits, and policy support is advocated to enhance soil fertility, crop yield, and environmental sustainability in Tanzanian agriculture.

Potential valorization and transformation of plastic biomass waste into useful fertilizers in agricultural Mediterranean soils under extreme climate conditions

Plastics are widely used in agricultural practices, although recently they have been recognized as a new emerging risk in soils. Polyethylene (PE), is commonly used by farmers to cover agricultural practices; geotextile, is used mainly for ground and crop covering; and polyvinyl chloride (PVC) is considered the main material contained in irrigation hoses. The present study aimed to assess the effects of three plastics (polyethylene, geotextile, polyvinyl chloride) on the soils’ fertility. Several pot experiments were conducted in soil samples from the study area (Thessaly) contaminated with adequate amounts of each plastic type (PE, geotextile: 2% v/v and PVC: 5% v/v). Water was added in two quantities: one to maintain typical soil moisture levels according to the crops’ requirements and an elevated amount to form supersaturating soil conditions similar to those following a flood event. Furthermore, temperature effect was also investigated to assess its impact on plastics’ behavior and soil fertility. The levels of all nitrogen forms and the microbial activity were determined at 10, 30, and 60 days. Significant changes were observed in the concentrations of nitrate, nitrite, and ammonium ions under ambient soil moisture conditions especially when the microplastics were incubated for a longer period. PE addition resulted in greater changes, followed by geotextile, although PVC addition did not induce significant changes in the nitrification process during the experimental time. PE and geotextile microplastics appeared to enhance microbial colonization and total microbial activity. In addition, soil characteristics were notably altered when moisture stress conditions were reached (85%) and when soils were flooded for two months, leading to a severe decrease in the availability of all nitrogen forms. The results showed that alterations in soil nitrogen forms in the presence of plastics study are crucial for maintaining the health and improving the productivity of Mediterranean soils.

Mapping of Water and Soil Quality Parameters in the Gampaha-Ihalagama East and Eldeniya East Grama Niladhari Divisions, Sri Lanka

Water and soil are important natural resources, and the study of their distribution is of great interest. The Grama Niladhari Divisions, Ihalagama-East and Eldeniya-East, located in the Gampaha district, are selected as the study areas, and this is done as a pilot study. Different water and soil quality parameters are investigated followed by the construction of contour maps. As water quality parameters, pH, conductivity, phosphate content, nitrate content, and Ca2+ hardness were determined, and as soil quality parameters, pH, nitrate, organic matter, water-soluble Na+ and K+, extractable Na+ and K+, and water-soluble Ca2+ ion contents were determined. The pH of water samples lies within the range of 4.41 - 7.11 and 3.79 – 7.18 in the Ihalagama-East and Eldeniya East divisions, respectively. Almost all the samples have acidic pH values, with some falling below the lower limit of the WHO guidelines for safe drinking water (6.5 - 8.5). Conductivity values vary from 52.0 - 277.0 µS/cm and between 54.0 – 403.0 µS/cm, respectively, which is below the WHO permissible level of 1500 µS/cm. The phosphate content varies from 1.374 - 3.986 mg/L in Ihalagama-East and water-soluble phosphate was not detected in Eldeniya-East, indicating a very low range and suggesting that the water samples are less contaminated with phosphate-containing substances. Considerably high values in the range of 1.24 - 279.00 mg/L for Ihalagama-east and 59.5 mg/L - 168.0 mg/L for Eldeniya-East, are obtained for the nitrate content where most of them are beyond the safe level of drinking water, 50 mg/L. The soil pH in all the samples falls within the acidic range, varying from 2.99 - 6.73 in Ihalagama-East and 3.07 – 6.68 in Eldeniya-East. Most of the soil samples contain high nitrate contents, indicating significant contamination. The percentage soil organic matter content varies between 0.60% and 13.27% in both areas. Many fertile agricultural soils typically have an organic matter content ranging from 3% - 6% revealing that most of the samples are beyond the standard levels. The distribution of water-soluble and extractable cations does not exhibit a wide range. According to the findings, though two Grama Niladhari Divisions are selected, they also display a huge variation. This reveals the importance of mapping to address contaminations, effects of natural disasters which lead to changes in the studied water and soil quality parameters.

Exploring the effect of different application rates of biochar on the accumulation of nutrients and growth of flue-cured tobacco (Nicotiana tabacum).

Biochar application has become one of the most potential tools to improve soil fertility and plant growth for sustainable and eco-friendly agriculture. However, both positive and negative effects of biochar application have been recorded on plant growth and soil fertility. This study investigated the impact of different application rates (0, 600, 900, 1200, and 1800 kg/ha) of biochar on the soil nutrient contents, accumulation of nutrients and dry matter in different plant parts, and growth of flue-cured tobacco plants under field conditions. Results demonstrated that soil organic carbon pool and carbon/nitrogen ratio were increased proportionally with the increasing dosage of biochar, 25.54 g/kg and 14.07 g/kg compared with control 17 g/kg and 10.13 g/kg, respectively. The contents of soil total nitrogen were also significantly increased after biochar application in the middle (1.77 g/kg) and late-growth (1.54 g/kg) stages of flue-cured tobacco than in control (1.60 g/kg and 1.41 g/kg, respectively). The contents of soil nitrate nitrogen were also higher under low (600 and 900 kg/ha) application rates of biochar and reduced when higher (1200 and 1800 kg/ha) dosages of biochar were applied. However, it was observed that varying application rates of biochar had no impact on soil ammonium nitrogen content during the growth period of flue-cured tobacco plants. The nutrient accumulation (N, P, K) in different parts of flue-cured tobacco plants was significantly increased under a low application rate of biochar, which enhanced the soil and plant analyzer development values, effective leaves number, growth, dry matter accumulation, and leaf yield of flue-cured tobacco. In contrast, the high biochar application rate (1200 and 1800 kg/ha) negatively impacted nutrient accumulation and growth of flue-cured tobacco. Conclusively, the optimum application of biochar (600 and 900 kg/ha) is beneficial for plant growth, soil fertility, accumulation of nutrients, and dry matter in different plant parts. However, excessive biochar application (> 900 kg/ha) could inhibit flue-cured tobacco plant growth. This study provides a theoretical foundation for biochar application in tobacco and other crop production to obtain agricultural sustainability and economic stability.

Influence of Protected Cultivation Structures on Vegetable Crops

Protected farming is a new technology that is being utilized to grow high-value crops like flowers, vegetables, and other perishable commodities. In contemporary agriculture, protected structures offered an enormous chance for greater productivity and production. Protected cultivation, which is the most effective way to deal with climatic variation provide favourable environment for crop growth thereby achieving greater yield and high-quality produce. Protected cultivation structures such as polyhouses, low tunnels, shadow shade net houses, and green houses are frequently used for crop cultivation. Further, the vegetables grown under these structures possess better quality, decreased pesticide residue and higher yields than the ones grown under open-field conditions. As compared to open field cultivation, the reduction in irrigation water requirement was 35.6 % for shadow hall, 35.2 % for polyhouse and 25.5 % shade net house cultivation. Shadow hall is most suited for the cultivation of vegetables as depicted by higher growth and yield parameters, followed by polyhouse, shade net house. Thus, in terms of enhancing agricultural production, soil fertility, profitability, and sustainability, among other aspects, protected structures-based farming is more beneficial than open field conditions. The analysis of the evaluation showed that compared to open environments, the gross and net returns under protected structures (protective cultivation) were much greater.

Methodology for Regional Soil Organic Matter Prediction with Spectroscopy: Optimal Sample Grouping, Input Variables, and Prediction Model

Soil organic matter (SOM) is an essential component of soil and is crucial for increasing agricultural production and soil fertility. The combination of hyperspectral remote sensing and deep learning can be used to predict the SOM content efficiently, rapidly, and cost-effectively on various scales. However, determining the optimal groups, inputs, and models for reducing the spatial heterogeneity of soil nutrients in large regions and to improve the accuracy of SOM prediction remains a challenge. Hyperspectral reflectance data from 1477 surface soil samples in Northeast China were utilized to evaluate three grouping methods (no groups (NG), traditional grouping (TG), and spectral grouping (SG)) and four inputs (raw reflectance (RR), continuum removal (CR), fractional-order differentiation (FOD), and spectral characteristic parameters (SCPs)). The SOM prediction accuracies of random forest (RF), convolutional neural network (CNN), and long short-term memory (LSTM) models were assessed. The results were as follows: (1) The highest accuracy was achieved using SG, SCPs, and the LSTM model, with a coefficient of determination (R2) of 0.82 and a root mean squared error (RMSE) of 0.69%. (2) The LSTM model exhibited the highest accuracy in SOM prediction (R2 = 0.82, RMSE = 0.89%), followed by the CNN model (R2 = 0.72, RMSE = 0.85%) and the RF model (R2 = 0.69, RMSE = 0.91%). (3) The SG provided higher SOM prediction accuracy than TG and NG. (4) The SCP-based prediction results were significantly better than those of the other inputs. The R2 of the SCP-based model was 0.27 higher and the RMSE was 0.40% lower than that of the RR-based model with NG. In addition, the LSTM model had higher prediction errors at low (0–2%) and high (8–10%) SOM contents, whereas the error was minimal at intermediate SOM contents (2–8%). The study results provide guidance for selecting grouping methods and approaches to improve the prediction accuracy of the SOM content and reduce the spatial heterogeneity of the SOM content in large regions.

Agronomic use of solarization technology on soil fertility and pest management in dryland agriculture

Agronomic use of solarization technology on soil fertility and pest management in dryland agriculture

Determination and assessment of the groundwater table and mineralization in irrigated areas (Xojeli district, Republic of Karakalpakstan)

Irrigated areas in the Aral Sea Basin are becoming highly saline due to the ascendant groundwater table and groundwater mineralization. This, in turn, leads to a decrease in soil fertility in agriculture and negatively affects the food security of basin countries. In the research work, seasonal changes in the groundwater table and mineralization during the periods of 2015 and 2023 were evaluated on the irrigated lands of the Xojeli district in the Republic of Karakalpakstan (Uzbekistan). Field monitoring was carried out on 142 observation wells using traditional methods of measuring the groundwater table and mineralization. Then, the obtained data was statistically analyzed, and maps based on the geoinformation system (GIS) were created by the inverse distance weighting (IDW) interpolation method for the study period. Furthermore, a correlation coefficient analysis was applied to find a relationship between climatic patterns, and groundwater table, and mineralization. Results based on statistical analysis present steady fluctuations in the groundwater table and wild fluctuations in mineralization over a period of nine years. The average water table below surface and mineralization in April was determined by 1.55 m and 2.94 g/l, in July by 1.78 m and 2.96 g/l, and in October by 2.18 m and 2.56 g/l. The visual maps created in accordance with the GIS-based method show that average values for the groundwater table in the irrigated areas were 1.5–2 m and 2–3 m (57.9% and 27.8%), and mineralization was 1-3 g/l and 3-5 g/l (62.4% and 36.5%). A correlation coefficient (r) shows a low relationship between the chosen variables.