Nitrogen supply to no-tillage crops, as influenced by mulch type, soil type and season, following pasture leys in the semi-arid tropics

J. P. Dimes, R. L. McCown and P. G. Saffigna
Australian Journal of Experimental Agriculture, 36, 8, 937-46,
This paper summaries the Nitrogen (N) cycle in a system in which pastures provide N for successive crops, and mulch at the time of crop establishment is provided by the killing of new pasture growth. The aim was further to provide a sound foundation for managing N supply in relation to demand in a climate that causes high variation and uncertainty for pasture N2 fixation and sequestering, the amount of early season re-growth, rate of mulch decomposition, nitrate leaching losses, and crop growth anf N demand. The research approach combined field studies with simulation modelling. A series of field studies that included bare fallow and grass and legume pasture leys on clay and sandy loam soils, were conducted at Katherine over 4 wet seasons to study subsequent mineralisation of N. Experimental results were used to test the performance of a simulation model for predicting the observed variations consequent upon the various management options.