Influence of some soil and pasture components on the growth of hill country pastures

Publisher Website
Google Scholar
Abstract
The responses by hill pastures of widely varying land slope, aspect, and grass species composition to nitrogen (N) fertiliser application in May and August 1980 and August 1981 were examined. The yields varied widely for control pastures of all slopes and differing grass species composition. In contrast, pasture responses to N application were much more uniform, with the greatest responses occurring in spring, and being obtained on easy, ryegrass-dominant areas. Although appreciable residual effects of N fertiliser were measured after the initial responses in spring 1980, net depressions occurred in spring 1981. This effect was greatest on steep slopes, and may be related to the lower soil N status of the steep slope trial site. Simple correlation analysis was used to relate total pasture yield from N (N-treatment yield) with pasture and soil parameters measured at the start of each trial period. Significant correlations of N-treatment yield were measured with land slope, both ryegrass and browntop contents of pasture, total soil N, and mineralised soil N after 90 days incubation. However, partial correlation analysis indicated that when the other factors were held constant none of the site factors listed above were individually important in autumn, and in spring only slope and pasture species composition were significantly related to total N-treatment yield. Similarly, simple correlation analysis showed that no individual pasture or soil parameter was strongly related to the pasture dry matter (DM) response to N addition (i.e., N-treatment yield-control yield) in autumn-winter 1980, spring 1980, or in spring 1981. Contrasting pasture growth rates and responses were measured by a trim technique, and compared with a before-and-after grazing measurement technique. Because of the simpler procedures involved with the trim technique it is probable that this provided the more realistic evaluation. Some concern is expressed over the use of a before-and-after grazing measurement procedure on small, fixed plots because of the attendant problems of minimising the confounding management effects that may occur.

This publication has 8 references indexed in Scilit: