Effect of defoliation management, nitrogen and grass overdrilling on the yield and quality of lucerne

Abstract

Lucerne (Medicago media) is of major interest in Canterbury partly because of its high yield potential and drought resistance. Traditionally lucerne was grown for hay, but more recently it has assumed importance for grazing. Recently the growing of this crop for dehydrated meal has become of increasing importance and potential exists for the expansion of this industry, mainly for export to Japan. The meal industry requires large quantities of lucerne, the supply of which must be spread over an extended period in order to keep production costs to a minimum. The lucerne must also be of high quality to meet contract specifications.

This study investigates the effects of cutting management and nitrogen fertilization on the seasonal dry matter yield, some quality factors and stand survival of irrigated Wairau lucerne grown on a moderately moisture retentive soil-type in Canterbury. Three factors affecting lucerne meal quality were investigated, namely the content of nitrogen, carotene and xanthophyll. These fractions were selected for determination because of their importance and ease of analysis. The possible role of Lolium multiflorum Lam. 'Grasslands Tama' Westerwolds in extending the seasonal spread of production was also investigated.

A summary of the results and the conclusions derived from them are given in the main part of this thesis. The results are presented in chronological order, but are discussed as a whole under three headings quality dry matter yields; nitrogen fixation; and quality.

Tables of primary data may be found in chronological order in the Appendices.