Testing vegetation index categories as influenced by soil management and nitrogen fertilization in cereal based cropping systems

Abstract

Mostly precision agriculture applications pass by an acquisition and elaboration of images, which allow us to detect the spatial-temporal variability of the crop, so it is fundamental understand how those images and relate vegetation indexes can be affected by farmers practices. We investigated how long-term conservation agriculture practices, in comparison with conventional practices, and nitrogen fertilization levels can affect the productivity of durum wheat and the accuracy of five vegetation index categories to well describe the biomass and nitrogen crop status. The experimental site is a part of a long-term experiment established in 1994 and is still on-going consisting on a rainfed 2 years rotation with durum wheat and maize, where two tillage management (no tillage vs conventional tillage) and three nitrogen fertilizer treatments (0, 90 and 180 kg N ha-1) were repeated in the same plots every year. At three different phenological stages we acquired multispectral imagery aimed to test the accuracy of vegetation indices to well represent the total biomass weight (gm-2) and biomass nitrogen content (g N m-2) in relation to the soil managements and nitrogen fertilization rates. In addition, at crop maturity, we measured the yield components for all compared treatments. The most important key driver in achieving maximum productivity is nitrogen fertilization. The accuracy of the vegetation indices depends on the soil managements, nitrogen fertilizations and background soil noise. The evaluation of which vegetation index use to represent the durum wheat status defines the quality of vegetation and prescription maps for precision agriculture applications.