Border and orientation effects and their elimination in experimental swards of subterranean clover (Trifolium subterraneum L.)

Abstract

Two experiments were carried out in swards of subterranean clover, of the variety Bacchus Marsh, to determine the width of the border required firstly at the edge of swards and secondly between harvest areas. Peripheral growth was restricted by (a) root panels, (b) leaf panels, and (c) root and leaf panels; a fourth treatment with no lateral restrictions was also used. The results showed that in a sward growing without restrictions, a border at the edge of only 2 in. was required before homogeneous dry weights were reached. This border effect could be eliminated by using leaf- or leaf- and root-restricting panels, but not by root panels alone. The data for borders between harvest areas were more difficult to interpret, but growing swards without panels while allowing for a 3 in. border, both at the periphery and between defoliated areas, is recommended as the simplest procedure. From a consideration of marginal growth under the different peripheral restriction regimes it was concluded that water and nutrients were non-limiting, but that sward growth was limited by the amount of light energy intercepted.