A comparison of the effects of mineral and organic nitrogen sources on the distribution of wheat roots in a leaching environment

Abstract

Wheat was grown under leaching conditions in columns in a glasshouse. Marked differences were observed in the root density profiles which resulted from addition of nitrogen in the form of either calcium nitrate or ground lupin leaves. The root profiles from the lupin leaf treatment had the highest density of roots at the surface and a continuous reduction in density with depth. Where calcium nitrate was added, total root growth was reduced, but there was enhanced growth of roots at depth associated with the leached nitrate. Water use was greater where lupin leaves were added, and the amount of top growth was also greater, although the difference was not significant. Nitrogen uptake was greater where calcium nitrate was added. Comment is included on the suitability of analysis of variance and repeated measurement methods for comparing profile data of the type collected here.