Forage yield, botanical composition and soil characteristics of a species diversity by harvest height experiment in Hawke’s Bay

Abstract

There has been considerable pastoral sector interest in regenerative agriculture practises and the potential impact of diverse forage mixes and grazing to higher residuals on pasture production and soil quality. This small plot study aimed to evaluate the productivity, botanical composition, and soil characteristics of four different forage mixtures under two mowing regimes over two years at a summer-dry site. The mixtures were: ryegrass/clover (4 species), plantain/clover (6 species) and two ‘hyper-diverse’ (31 species sown at 45 or 180 kg/ha). The two mowing heights were 8 cm and 20 cm to replicate lax and very lax grazing management systems. The diverse mixtures produced more feed in the first six months due to the presence of cereals and brassicas. In fact, these vigorous annuals may have reduced the success of other species as only a small number of species in the diverse plots were present after 2 years. The 8 cm cutting height produced a mean of 26 185 kg DM/ha and the 20 cm cutting height produced a mean of 15 951 kg DM/ha across the four forage mixtures. Within the 20 cm mowing height the two diverse mixes produced the most herbage while within the 8 cm mowing height the plantain/clover mix and hyper-diverse mix at a high sowing rate produced the most herbage. There was no effect of forage mix or mowing height on soil carbon, soil nitrogen, water infiltration rates, earthworm abundance or decomposition activity over the two year period.