Yield and persistence of legume monocultures grown in the Lees Valley, South Island High Country

Six legume monocultures were established in the Lees Valley, North Canterbury (400 m a.s.l.), which has long cold winters. The stony soils have low pH, high aluminium concentration, and low water holding capacity, which can lead to severe summer soil moisturedeficits. The aim was to identify legumes that would survive and persist in this environment and, therefore, increase the available nitrogen in the pastoral system. Legume populations of 88±12 seedlings/m2 were established and ranged from 45 (sub clover) to 197seedlings/m2 (Caucasian clover). The highest yields were from ‘Pawera’ red clover at 2.5 and 2.9 t DM/ha in Years 2 and 3, ‘Demand’ white clover produced 1.7 and 2.6 t DM/ha, and ‘Endura’ Caucasian 1.8 and 1.7 t DM/ha. ‘Kaituna’ lucerne yields were low at 0.7 and 1.4 t DM/ha. Caucasian clover was the most persistent legume. A visual assessment in Year 5 found Caucasian was the only legume still dominating its plot (69%) with the lowest area of bare ground (11%). ‘Leura’ subterranean and ‘Bolta’ balansa annual clovers survived for four years but accumulated annual yields were low (<1.0 t DM/ha/yr), and the presence of unsown species was high (>50%). While red and white clover provided the highest yields for two years, Caucasian clover was the most persistent species and istherefore a legume recommended for this environment.