Udayarpillai Surendran

Nanotechnology is showing promise as a revolutionary strategy to improve crop productivity, environmental sustainability and resource efficiency. Nano clay polymer composites (NCPCs) have drawn considerable interest among advanced nanomaterials because of their distinct physicochemical characteristics and broad agricultural applications. Montmorillonite, Bentonite and Hectorite are examples of nano clays, which are layered silicate minerals with large surface area, nanoscale dimensions and potent adsorption capabilities. They form hybrid materials with enhanced mechanical strength, thermal stability and barrier properties when integrated into polymer matrices. Water, nutrients and agrochemicals flow through a convoluted diffusion pathway created by the layered structure of nano clays, allowing for regulated and prolonged release. The NCPCs can have phase-separated, intercalated, or exfoliated structures depending on how they are dispersed within the polymer matrix; exfoliated forms function better. In agricultural applications, NCPCs function as soil conditioners, smart fertiliser carriers and plant protection delivery systems. They improve soil aggregation, enhance water retention and increase nutrient availability, particularly in coarse-textured soils. Nano-enabled fertilisers facilitate synchronised nutrient release, improving nutrient use efficiency while minimising leaching and volatilisation losses. Emerging applications include delivery of nucleic acids for plant disease management, antimicrobial crop protection and micronutrient nanocomplexes that enhance bioavailability and soil biological activity. Overall, NCPCs offer a promising pathway toward sustainable and precision agriculture, Future research should focus on developing biodegradable polymer systems, optimising scalable synthesis methods, conducting long term field evaluations and estabilishing regulatory frameworks to enable their safe and agricultural application.

NUTrient MONitoring (NUTMON) is interactive computer software that helps decision-makers use data and models to solve unstructured problems. An attempt was made to carry out nutrient audits, which include the calculation of nutrient balance at the field (farm) level and the evaluation of trends in nutrient mining/enrichment using the NUTMON-Toolbox. Nutrient Monitoring (NUTMON) is a multiscale approach that assesses the stocks and flows of N, P, and K in a well-defined geographical unit based on the inputs viz., mineral fertilizers, manures, meteorological data, atmospheric deposition, sedimentation, and outputs of harvested crop products, residues, leaching, denitrification, and erosion losses. The nutrient budgeting study was carried out using the NUTMON model for the Long-term fertilizer experiment trial, adopting the standard procedures and calculations (viz., Chemical fertilizers and Integrated nutrient management). The calculated nutrient balances at crop activity level indicated a Positive balance for nitrogen and phosphorus in 100 % NPK + FYM @10 t ha-1, and a negative balance was observed for potassium in all maize treatments. The results revealed that the nutrient management practices are not appropriate and sustainable. Management options to mitigate this mining by judiciously manipulating all inputs and outputs through an integrated system approach are suggested, and one way to redefining the nutrient recommendation based on site-specific requirements was worked out. A strategy was worked out to derive the nutrient prescription rate using site-specific soil test results for the individual crops of the selected farms. By assuming prescribed nutrients are applied to the individual PPUs, nutrient balances were simulated with NUTMON-Toolbox, and the results indicate positive balances for N and P and negative balances for K.

The Western Ghats region of India, being one of the most ecologically significant regions globally, it is crucial to understand the critical impacts of climate change in this region. In the present study, we have investigated the precipitation patterns across the Northern and Southern Peaks of the southernmost region of the Western Ghats (i.e., falling in the Kerala state, India), by employing precipitation indices recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI), World Climate Research Programme (WCRP), and through statistical analysis of India Meteorological Department (IMD) precipitation data during 1986–2022 time periods using the non-parametric modified Mann–Kendall test and Sen’s slope estimator. The results indicated that the Northern Peak region of Kerala state witnessed lower average rainfall and less variability, as compared with the Southern Peak region, with distinct differences in extreme precipitation patterns. The Northern Peak is characterized by extended dry spells, as evidenced by increased positive trends in consecutive dry days (CDD), in addition to consecutive wet days (CWD), total precipitation (PRCPTOT), and extreme rainfall events, such as PRge1 and PRge2.5 days. These changes are accompanied by an upward trend in the simple daily intensity index (SDII), indicating a shift towards more intense and variable rainfall. In contrast, the Southern Peak shows significant decreases in CWD, PRCPTOT, and SDII. Despite high precipitation in the Southern Peak, there is a reduction in extreme rainfall indices such as rainfall exceeding 1 mm or 2.5 mm (PRge1/PRge2.5 days) and heavy precipitation days (R10mm, R20mm, R30mm), reflecting a decline in rainfall intensity and frequency. The study revealed distinct precipitation patterns, where the Northern Peak faces increased intensity and variability in rainfall, while the Southern Peak shows reduced rainfall intensity and variability. Understanding regional differences in topography and microclimate is crucial for mitigating the impacts of extreme weather events, such as floods, droughts, and landslides. Developing effective management strategies tailored to the specific climate challenges of vulnerable areas in each peak is essential for enhancing resilience to natural calamities in the Western Ghats, India.

This study evaluated the effects of different irrigation methods, varying levels of water deficit, and irrigation intervals on transpiration, soil evaporation, crop growth, and yield of cowpea (Vigna unguiculata) under field conditions. The assessment was conducted using the food and agriculture organization-56 dual crop coefficient method across seven irrigation treatments. In the I1, I2, and I3 treatments, irrigation was applied through a drip irrigation system at 100%, 80%, and 60% of crop evapotranspiration (ETc), respectively. In contrast, in the I4, I5, and I6 treatments, irrigation was provided at 100% of ETc when soil moisture depletion reached 45%, 60%, and 75% of the management allowed depletion threshold, respectively. The I7 treatment consisted of conventional furrow irrigation applied at four-day intervals. The results revealed that variable irrigation intervals in the I4, I5, and I6 treatments resulted in seasonal soil evaporation (E) savings of 17.4%, 29.9%, and 42.8%, respectively, compared to the treatments receiving frequent irrigation at two-day intervals. Furrow irrigation (I₇) doubled the evaporation losses as compared to drip irrigation. Under deficit irrigation in I2 and I3, transpiration (T) decreased by 18.5% and 42.7%, while ETc was reduced by 13.2% and 30.6%, respectively. Conversely, only 4.8% and 16.2% reductions in transpiration were observed under I5 and I6, respectively. The non-frequent irrigation regime in I4, I5, and I6 decreased seasonal ETc by 5.0%, 12.0%, and 23.8%, respectively, whereas furrow irrigation (I7) increased ETc by 28.1%. The highest growth and yield attributes were observed in drip-irrigated I1 and I4 treatments, as confirmed through spectral signatures and vegetation indices. The maximum yield of cowpea (11.57 tons per hectare) was recorded in I4, which was statistically on par with I1 and I7. The lowest yield was observed in the severely water-stressed I3 and I6 treatments. Deficit irrigation in I2 and I3 significantly improved the Water Productivity (WP, kg/m³)–Yield per unit of total crop evapotranspiration, Transpiration Use Efficiency (TrUE, kg/m³)–Yield per unit of transpiration, Irrigation Water productivity (IWP, kg/m³)–Yield per unit of irrigation water applied and Biomass Transpiration Productivity (WPTr, kg/m³)–Biomass per unit of transpiration. The study highlights the potential of deficit irrigation strategies (I2 and I3) to enhance water productivity and efficiency, while non-fixed irrigation intervals (I4, I5, and I6) contribute to reducing soil evaporation losses. Drip irrigation at 100% ETc with a non-fixed irrigation interval (I4) emerged as the most effective treatment, optimizing both yield and water conservation. These findings have significant implications for improving irrigation management in water-scarce regions.