Assessment of nitrification rates of soils and screening of plant materials for nitrification inhibition properties

Abstract

The present study ‘assessment of nitrification rates of soils and screening of plant materials for nitrification inhibition properties’ was conducted during January 1993 to August 1993 at the College of Horticulture, Vellanikkara, Trichur. The three soil types, laterite, alluvial and forest were used for nitrification rate assessment. The two soil types, laterite and alluvial were taken from different locations of variable crop association. A total of 13 samples were assessed. One soil sample with the maximum rate of nitrification from these were taken for screening of plant materials for nitrification inhibition properties. Fourteen different locally available plant materials were chosen for screening using N-Serve and neem cake as the standard inhibitors for comparison. Nitrification rate in nearly all the soil was low and there was no appreciable conversion of NH4 from to NO3. A distinct crop associated influence on nitrification rate was absent in the soils studied. The only exception was the alluvial sample with banana as the associated crop and this soil was hence chosen for screening of plant materials. N-Serve was found to be the most effective nitrification inhibitor. Among the plant materials tested, cashew shell was the only material which showed a distinct advantage over other materials including neem cake. Highest mean values in plant height and number of leaves at different growth stages and dry matter production, N content and N uptake were observed in the treatment receiving cashew shell. Other useful materials identified were tobacco waste, calotropis leaf, neem leaf and castor cake.