Pastoral fallow for improving low fertility hill country pastures

Abstract

The effect of a pastoral fallow (the 'spelling' of a pasture from early spring (September) to autumn (April/May)), with or without added fertiliser, on pasture and legume growth rates, total pasture biomass accumulation, nitrogen fixation, and on soil carbon and nitrogen cycling in the year of the fallow, and in the year after thef allow, wa sevaluated on 55ha of moderate to steep~low fertility, summermoist hill country at Ballantrae, DSIR Grasslands Hill Country Research Station. The major effect was to open the sward, increase individual plant size, vigour and rooting depth, increase the presence and vigour of white clover by creating new niches for growth, and improve N fixation by legumes in the year after the fallow only. The data on soil C and N dynamics are consistent with the concept of fallowing adding a pool of potentially available N to the soil. The benefits of a fallow for moist hill country and other pastoral farming systems are discussed. Keywords pastoral fallow, hill pastures, nitrogen, legume growth