Residual Effect of Different Sources of Nutrients on Available NPK in Soil after Harvest of Maize in Rice Fallow Maize Cropping System

A field experiment was conducted for two consecutive years (2011-2012 and 2012-2013) on fine texture soils of Agricultural college farm, Bapatla. The experiment was laid out in a randomized block design in kharif season with four treatments. The treatments consisted of M1 (RDF (Recommended dose of fertilizers) - Control), M2 (10t FYM (Farm Yard Manure) ha-1 + RDF), M3 (1.5t vermicompost ha-1 + RDF), M4 (Green manuring + RDF). During the immediate rabi, the experiment was laid out in a split-plot design without disturbing the soil for succeeding maize with the four treatments given to kharif rice as main plot treatments and each of these divided into five sub-plots to receive five levels of fertilizer NPK application viz., N1 - 75% NPK, N2 - 100% NPK, N3 - 125% NPK, N4 - 150% NPK and N5 - 175% NPK for succeeding maize.

Data collected on available NPK after harvest of maize crop were significantly increased with the application of 100% NPK in combination with FYM @10t ha-1 to preceding rice crop, irrespective of the NPK levels applied to succeeding maize crop. However, it was on par with that of green manuring together with 100% NPK during both the years of the study.