The response of maize to four rates of nitrogen (N) fertiliser (0, 60, 120 and 240 kg N ha−1) on an ultisol in south-eastern Nigeria was evaluated under two tillage and two mulch treatments. Differences in plant height, leaf area index and grain yield between the conventionally tilled and zero-tillage treatments were not significant at P < 0.05, but the mulched plots out-yielded the unmulched plots by 23–46% during the drier seasons. On each tillage-mulch combination, grain yield response to nitrogen was of a quadratic polynomial form, indicating that maximum yields occurred at 123, 139, 130 and 142 kg N ha−1 on the tilled-mulched, tilled-unmulched, untilled-mulched and untilled-unmulched plots, respectively. Nitrogen use efficiency (grain yield per kg N applied) decreased in the order tilled-mulched (32.6) > untilled-mulched (30.9) > untilled-unmulched (27.8) > tilled-unmulched (22.4) where the figures in parentheses represent nitrogen use efficiency (kg kg−1).For each tillage treatment maximum soil temperature was higher and moisture retained at 2 and 10 days after saturation lower on the unmulched than mulched plots. Percentage moisture loss between these days was 45.5, 83.3, 25.0 and 55.6 respectively, on the tilled-mulched, tilled-unmulched, untilled-mulched and untilled-unmulched plots. The untilled-mulched plots had the highest contents of residual organic carbon and total N.
Journal of the Science of Food and Agriculture 01/1990; 52(3):365 – 376. DOI:10.1002/jsfa.2740520309