Influences of two-year red clover-grass ley management on nitrogen economy and following wheat performance

摘要

A two-year ley field experiment was established in May 2009 with six combinations of red clover, perennial ryegrass and cocksfoot, and two fallow control plots, to determine the impact of 'cut and remove' of the crops three times or 'cut and mulch' once annually on biomass yield, nitrogen (N) accumulation, soil mineralization and subsequent cereal performance. Farmyard manure was added to one of the fallow treatments at the beginning of the arable phase. The experiment was conducted on a clay loam soil at Moreton-in-Marsh, Gloucestershire, UK (NGR SP 217 323). During the ley fertility-building phase, there was no evidence that red clover (RC) had a synergistic effect on grass productivity when in mixtures, irrespective of cutting system. Accumulated above ground N over the 2years was greater in cut/removed red clover-based leys (330-365kgha(-1)) grass and fallow plots. In cut/mulched leys, RC was higher (113kgha(-1)) than the rest. Soil potential mineralizable N (PMN) was not related to ley N yields but was consistently high in the red clover/ryegrass/cocksfoot (RCRGCF) treatments during winter and spring wheat. There was no indication that wheat yields and quality were improved following any red clover combinations or cutting regimes. These results suggest mixing RC with two grasses, RG and CF are likely to improve soil mineralization potential. Nevertheless, growing red clover leys over 2years and mulching once annually under variable weather could limit soil N accumulation. In such conditions, growing red clover leys for a shorter period and removing herbage may be a better option.