Journal of Agricultural Engineering

Knowledge about soil nutrient status is vital in precision agriculture for site-specific nutrient management, which is the key to improve nutrient application efficiency and boost crop productivity. A study was conducted in Malappuram district of Kerala, India where a total of 70 soil samples were collected at a grid interval of 50 m × 50 m to determine status of soil nutrients including pH, electrical conductivity (EC), organic carbon, available nitrogen, available phosphorus and available potassium. Then, spatial mapping of the soil parameters was accomplished by employing inverse distance weighting (IDW) method of spatial interpolation in geographic information system (GIS) environment. Furthermore, dynamics of variable soil nutrients due to fertigation in tomato crop was monitored at two test sites, one at high soil fertility zone and another at low fertility zone. The results indicated that soil pH in the study area ranged from strongly to slightly acidic with low EC values, which is considered safe for plant growth. The low EC value of soil is likely due to high rainfall and minimal salt accumulation in the soil. The results of nutrient analysis revealed that nitrogen and potassium levels were in the ‘low fertility’ class, while phosphorus was in ‘high fertility’ class. The nutrient dynamics study showed that concentrations of three primary nutrients were highest at the points close to the drippers, especially at 15-30 cm depth, which suggests efficient nutrient delivery through the watering system. Overall, nutrient levels declined with soil depth and distance from the dripper, which emphasized the need for precise fertilizer application. The contrasting fertility levels suggest that blanket fertilizer recommendations may be inefficient and potentially lead to nutrient imbalances or environmental stress. On the other hand, sitespecific nutrient management strategies have the potential for promoting both economic savings and environmental stewardship.