Field capacity (F.C.) is a crucial parameter in soil analysis, defining the limits of plant-available moisture content (M.C.). Integrating this concept into sensing technology provides valuable information for optimizing irrigation scheduling by determining the appropriate timing and quantity of irrigation, thereby preventing crop damage. This article presents a fractal-based microwave planar sensor (MPS) designed to estimate soil-moisture characteristics related to F.C. The proposed sensor utilizes a self-similar fractal (SSF) approach, operating in the ISM frequency band at 2.4 GHz, achieving high return losses of approximately -47.94 dB and enhanced sensitivity in material characterization. The sensor's performance is evaluated by varying F.C. values from 0% to 100% for similar textured soils with organic matter content (OMC) variations. The results demonstrate that variations in OMC significantly impact the dielectric properties of soil with moisture variations. Specifically, Sample-1, which has a low OMC, exhibits a lower epsilon(r) values than Sample-2 at all F.C. levels. The data suggest that the proposed sensor is sensitive to detect the impact of OMC variations on soil-moisture characteristics concerning F.C. A mathematical model has been formulated as a second-order polynomial equation, exhibiting coefficient of determination (R-2) value of 0.9771. This model has been developed specifically to evaluate F.C. values, demonstrating a strong correlation with the observed data. The performance of the proposed sensor confirms its potential application in agricultural fields for efficient irrigation scheduling and water resource conservation.

Drought stress induces a range of physiological changes in plants, including oxidative damage. Ascorbic acid (AsA), commonly known as vitamin C, is a vital non-enzymatic antioxidant capable of scavenging reactive oxygen species and modulating key physiological processes in crops under abiotic stresses like drought. Chickpea (Cicer arietinum L.), predominantly cultivated in drought-prone regions, offers an ideal model for studying drought tolerance. We explored the potential of AsA phenotyping to enhance drought tolerance in chickpea. Using an automated phenomics facility to monitor daily soil moisture levels, we developed a protocol to screen chickpea genotypes for endogenous AsA content. The results showed that AsA accumulation peaked at 30% field capacity (FC)-when measured between 11:30 am and 12:00 noon-coinciding with the maximum solar radiation (32 degrees C). Using this protocol, we screened 104 diverse chickpea genotypes and two control varieties for genetic variability in AsA accumulation under soil moisture depletion, identifying two groups of genotypes with differing AsA levels. Field trials over two consecutive years revealed that genotypes with higher AsA content, such as BDNG-2018-15 and PG-1201-20, exhibited enhanced drought tolerance and minimal reductions in yield compared to standard cultivars. These AsA-rich genotypes hold promise as valuable genetic resources for breeding programs aimed at improving drought tolerance in chickpea.

Generally, nanotechnology plays an very important role in various applied scientific fields. Iron and magnesium nanoparticles (NPs) can cause positive or negative changes in soil physical and mechanical properties, especially in long periods. The aim of this study was to investigate the multi-year effects of NPs on soil water retention and aggregate tensile strength. A wheat farm loamy soil was amended with 1%, 3%, and 5% (weight/weight) of magnesium oxide (MgO) and iron oxide (Fe3O4) NPs in three replications and incubated for three years. Water contents were measured at different matric suctions of 0, 10, 20, 40, 60, 100, 300, 1 000, and 15 000 cm. The van Genuchten model was fitted to the moisture data. Tensile strength was measured on the 2-4 mm aggregates at matric suctions of 300 (i.e., field capacity) and 15 000 (i.e., permanent wilting point) cm. The results showed that the levels of 1% and 3% Fe3O4 NPs significantly increased water retention, compared to the no NP application control and 5% MgO NPs, which is probably due to the increase of adsorption surfaces in the treated soils. Water contents at field capacity and permanent wilting point in the 5% MgO NP treatment decreased compared to those of the other treatments, due to the increased soil vulnerability and reduced soil fine pores. The application of Fe3O4 NPs did not have any significant effect on soil tensile strength. Based on the results of this study, soil physical and mechanical properties could be affected by NP application.