Indian agriculture is characterized by small farm size and large number of farm holdings where adoption of soil test-based fertility management is a big challenge under prevalence of high degree of spatial variability and lack of infrastructure for extensive soil testing. Under such circumstances, GIS based soil fertility mapping appeared as a promising alternative. Geographic Information Systems spatially analyzes the soil characteristics and is useful to produce interpolated maps for visualizing the soil variability. Use of such maps as a decision support tool for nutrient management will not only be helpful for adopting a rational approach over farmer's fertilization practice or government's state fertilizer recommendations, but will also reduce the necessity for elaborate individual field based soil testing activities. Understanding spatial variability of soil nutrients is important for refining the agricultural management practises and for improving sustainable land use. Studies on use of GIS based fertility maps has been limited in Indian conditions and very little work has been carried out in assessing the soil variability in Tamil Nadu. Thus the proposed study was initiated to assess the relative efficiency of GIS map-based soil fertility evaluation vis-a-vis the conventional soil testing approaches in the rice growing soils of Cuddalore district in Tamil Nadu.

Objectives

1. To compare the spatial variability of soil nutrients for different grid spacing.
2. To study the effect of variability based nutrient management on productivity of Rice crop.
3. To evaluate the efficacy of fertility maps for fertilizer decision support in the study area.