By the year 2050, the world’s population is predicted to have grown to around 9–10 billion people. The food demand in many countries continues to increase with population growth. Various abiotic stresses such as temperature, soil salinity and moisture all have an impact on plant growth and development at all levels of plant growth, including the overall plant, tissue cell, and even sub-cellular level. These abiotic stresses directly harm plants by causing protein denaturation and aggregation as well as increased fluidity of membrane lipids. In addition to direct effects, indirect damage also includes protein synthesis inhibition, protein breakdown, and membranous loss in chloroplasts and mitochondria. Abiotic stress during the reproductive stage results in flower drop, pollen sterility, pollen tube deformation, ovule abortion, and reduced yield. Plant nutrition is one of the most effective ways of reducing abiotic stress in agricultural crops. In this paper, we have discussed the effectiveness of different nutrients for alleviating abiotic stress. The roles of primary nutrients (nitrogen, phosphorous and potassium), secondary nutrients (calcium, magnesium and sulphur), micronutrients (zinc, boron, iron and copper), and beneficial nutrients (cobalt, selenium and silicon) in alleviating abiotic stress in crop plants are discussed.

The crop residues generated in agricultural fields are mostly considered a burden due to their disposal issues. This study attempts to effectively use pigeon pea stalk (PPS) for biochar production, a promising source as a soil amendment for carbon sequestration and alternative fuel source. PPS was pyrolyzed at different loads and reaction times to optimize the kiln temperature (350–400 °C and 450–500 °C) and changes in physicochemical properties, higher heating value (HHV) and yield were assessed. The results indicated that biochar yield, volatile matter, bulk density, O/C and H/C atomic ratios decreased, whereas fixed carbon, ash content and total porosity increased with increasing kiln temperature across all loads. Biochar produced at 450–500 °C (18 kg load kiln⁻¹) had higher total carbon, nitrogen, phosphorous, recovered total carbon and total nitrogen, total potential carbon and CO₂ reduction potential. Biochar produced at 350–400 °C had the maximum cation exchange capability (43.0 cmol kg⁻¹). Biochar has estimated O/C and H/C atomic ratios of 0.07–0.15 and 0.35–0.50, respectively. Biochar exhibited good agronomic characteristics and fulfilled key quality criteria of H/C < 0.7 and O/C < 0.4 for soil carbon sequestration, as described by the European Biochar Certificate and the International Biochar Initiative. The estimated mean residence time and the mass fraction of carbon that would remain after 100 years were consistently greater than 1000 years and 80%, respectively. The biochar produced at 450–500 °C (at 18.0 kg kiln⁻¹) from PPS had higher fixed carbon (65.3%), energy density (1.51), energetic retention efficiency (53%), fuel ratio (4.88), and HHV (25.01 MJ kg⁻¹), as well as lower H/C and O/C ratios, implying that it is suitable for use as an alternative solid fuel.

Organic agriculture’s economic benefits and widespread adoption are well documented, but its impact on soil C dynamics in rainfed regions of semiarid tropics is less understood. The use of organic amendments in organic farming not only supply nutrients but also have the potential to contribute to soil carbon sequestration. Carbon storage and various soil organic pools are affected differently by various crops and production systems. A study was conducted with three crops (sunflower, pigeonpea, and greengram) under three production systems (control, organic and integrated) to assess the effect on soil C stocks, carbon sequestration potential, and crop yield. After seven years of experiment, pigeonpea (Cajanus cajan L.) cultivation improved soil bulk density, porosity and water holding capacity compared to greengram [Vigna radiata (L) Wilczek] and sunflower (Helianthus annuus L.). Furthermore, plots under pigeonpea cultivation being on par with greengram had 15.6% higher total C (113.52 Mg C ha⁻¹), 14% higher easily oxidizable organic C (17.5 Mg C ha⁻¹) and C sequestration rate of 1.22 Mg C ha⁻¹ yr⁻¹ compared to sunflower. Among the three production systems, plots under organic management had significantly lower bulk density and higher water holding capacity and porosity at all of the profile depths compared to integrated production system and control. Similarly, organic production system being on par with integrated production system improved the easily oxidizable, oxidizable and weakly oxidizable organic C fractions at different soil depths compared to control. The C sequestration rate ranged from 0.21 to 0.85 Mg C ha⁻¹ yr⁻¹ in organic production systems compared to negligible rate (0.01–0.04 Mg ha⁻¹ yr⁻¹) in the plots under control. On average, integrated production system being on par with organic management recorded significantly higher pigeonpea equivalent seed yield (886 kg ha⁻¹) compared to control (792 kg ha⁻¹). These results suggest the potential of organic production system in improving soil properties, C sequestration, and crop yields in semiarid rainfed areas.

Globally, rice is one of the most important staple food crops. The most significant metric for evaluating the rice growth and productivity is the Leaf Area Index (LAI), which can be effectively monitored using remote sensing data. Hyperspectral remote sensing provides contiguous bands at narrow wavelengths for mapping LAI at various rice phenological stages, and it is functionally related to canopy spectral reflectance. Hyperspectral signatures for different phases of rice crop growth was recorded using Airborne Visible Near-Infrared Imaging Spectrometer-Next Generation (AVIRIS-NG) along with corresponding ground based observations. Ground-based hyperspectral canopy spectral reflectance measurements were recorded with FieldSpec 3 Hi-Res spectroradiometer (ASD Inc., Forsyth County, GA, USA; spectral range: 350–2500 nm) and LAI data from 132 farmer’s fields in Southern India. Among 29 hyperspectral vegetation indices tested, 8 were found promising for mapping rice LAI at various phenological stages. Among all the growth stages, the elongation stage was the most accurately estimated using vegetation indices that exhibited a significant correlation with the airborne hyperspectral reflectance. The validation of hyperspectral vegetation indices revealed that the best fit model for estimating rice LAI was mND₇₀₅ (red-edge, blue, and NIR bands) at seedling and elongation, SAVI (red and NIR bands) at tillering and WDRVI (red and NIR bands) at booting stage.

Mineral and vitamin deficiencies together affect a greater number of human populations in the world than does protein malnutrition. Organic farming is reported to improve nutritional quality of food grains while also improving soil health. However, sufficient scientific information on several aspects of organic farming based on long-term studies is lacking particularly under rainfed conditions of India. The purpose of this study was to assess the long-term impact of organic and integrated production systems on crops yield and quality, economic returns and soil properties. The study was conducted with three crops, sunflower (Helianthus annuusL.), pigeonpea (Cajanus cajanL.), and greengram [Vigna radiata(L.) Wilczek] under three different production systems, control (use of chemical inputs alone), organic and integrated. The results of the 10-year study revealed that, the average production of integrated system was on par with organic management and recorded significantly higher pigeonpea equivalent yield (PEY) (827 kg ha⁻¹) compared to control (chemical inputs) (748 kg ha⁻¹). In general, the yield gap between organic and integrated production systems declined from fourth year for greengram and eighth year for sunflower, during the 10-year experimental period whereas the pigeonpea yield was similar under both production systems from first year. Plots under organic management had significantly lower bulk density (1.18 mg m⁻³), higher water holding capacity (38.72%) and porosity (53.79%) compared to integrated production system and control (chemical inputs). The soil organic C (SOC) content in the plots under organic production system was 32.6% more than the initial organic carbon of the soil (0.43%), with higher soil N (205.2 kg ha⁻¹). Plots under integrated production system, however, had higher soil P (26.5 kg ha⁻¹) compared with other treatments. The dehydrogenase activity (5.86 μg TPF g⁻¹soil h⁻¹) and microbial biomass carbon (317.3 μg g⁻¹soil) content was higher in the plots under organic production system than under other systems. Organically produced pigeonpea and greengram seeds had similar protein content with that of integrated system, and higher K and micronutrient (Fe, Zn, Cu, and Mn) contents than other treatments. The results show the potential of organic production system in improving crop yields, soil properties and produce quality in semiarid rainfed areas.

Finger millet (Eluesine coracana L.) is gaining importance as a food crop with the increasing emphasis on nutritional aspects and drought resilience. However, the average productivity of the crop has stagnated at around 2,000 kg ha⁻¹ in India. Recently released nutrient responsive high yielding varieties are reported to respond better to application of fertilizers/manures. Further, substitution of chemical fertilizers with organic manures to maintain sustainable yields and improve soil health is gaining attention in recent years. Therefore, identifying the appropriate rate and source of nutrition is important to enhance the productivity of finger millet while improving the soil health. A field experiment was conducted during two rainy seasons (July–November, 2018 and 2019) to study the response of finger millet varieties to chemical fertilizers and farmyard manure (FYM) on growth, yields, N use efficiency, N uptake and on soil properties. Two varieties MR-1 and MR-6 were tested with four nutrient management practices viz., unamended control, 100% recommended dose of fertilizers (RDF; 40–20-20 kg NPK ha⁻¹), 50% RDF + 50% recommended dose of nitrogen (RDN) as FYM and 100% RDN as FYM. Among the varieties, MR-6 outperformed MR-1 in terms of growth, yield, N use efficiency and N uptake. The yield enhancement was up to 22.6% in MR-6 compared to MR-1 across the nutrient management practices. Substituting FYM completely or half of the fertilizer dose increased the growth and yield of finger millet compared to application of chemical fertilizers alone. Similarly, the average biomass yield, ears m⁻², grain yield, total N uptake and N use efficiency in response to nutrient management practices followed the order of 100% RDN as FYM > 50% RDF + 50% RDN as FYM > 100% RDF. The soil organic carbon, available N, P, K, and S improved by 25.0, 12.9, 5.7, 6.1, and 22.6%, respectively in the plots under higher rate of FYM application (8 Mg ha⁻¹) compared to plots under chemical fertilizers alone. We conclude that substituting chemical fertilizers either completely or by up to 50% with organic manures supplies adequate amounts of nutrients, improves the yield of finger millet, economic returns, and soil properties.