Caucasian clover responses to fertiliser, lime and rhizobia inoculation at Lake Heron Station, Canterbury

The agronomic performance of Caucasian clover in high country grasslands was the subject of two experiments at Lake Heron Station, Canterbury. In the first experiment, Caucasian clover was direct drilled into an undeveloped pasture (soil pH = 5.5; Olsen P = 7 mg/ litre) with fertilisers containing similar P and S but ± 20 kg/ha of N, in December 2011. After 11 months, shoots of Caucasian clover were small (3 mg), indicating an inoculation failure, and effects of fertilisers were not biologically meaningful. Therefore, the influence of rhizobia inoculant, superphosphate and lime on early growth of Caucasian clover was assessed using the same soil in a glasshouse. Un-inoculated plants were 13–24% the size of inoculated plants and this lack of vigour was not overcome by fertilisers. In the second field experiment, an established Caucasian clover/ browntop pasture (soil pH = 5.5; Olsen P = 5 mg/litre) received 0, 100, 200 and 400 kg/ha of superphosphate with 0 or 5 t/ha of lime in February 2012. Despite the high inputs, spring pasture yields 9 and 21 months after fertiliser application were low (1260–2400 kg DM/ ha), but the contribution of Caucasian clover was high (66–76%). Keywords: high country, nitrogen, phosphorus, Trifolium ambiguu