Effect of deep ripping, the previous crop, and applied nitrogen on the growth and yield of a wheat crop

Abstract

The response, to ripping and nitrogen application, of a wheat crop which has grown after a 1 -year crop of wheat, lupins and pasture was measured in terms of tops growth, nitrogen uptake, rooting depth and grain yield. Although there were limitations to the data set used, a graphical method demonstrating separation of the effects of treatment on soil nitrogen status and nitrogen use efficiency was compared using the classical analysis of variance. Ripping increased the rate of root extension and this caused the more efficient use of fertiliser nitrogen early in the season. Compensatory nitrogen uptake took place late in the season on the unripped plots. However, grain and tops yields were significantly greater on the ripped plots. The major effect of a previous crop of lupins was to increase the nitrogen status of the plots, although early in the season the efficiency of nitrogen use was also improved. A dry finish to the season turned a statistically non-significant ripping x nitrogen x species interaction for tops growth into a significant negative interaction for grain yield.