OVERSOWING WHITE CLOVER INTO CLEARED AND UNIMPROVED NORTH ISLAND HILL COUNTRY - THE ROLE OF MANAGEMENT, FERTILISER, INOCULATION, PELLETING AND RESIDENT RHIZOBIA.

Abstract

The roles of inoculation, pelleting and fertiliser were examined when white clover was oversown into recently cleared North Island hill country with a low resident white clover rhizobia population. Inoculation aided establishment at some sites. Recovery of inoculant strain from plants and soil was generally low, initial nodulation by the inoculant strain being replaced by expanding resident rhizobial populations. Pelleting was necessary to ensure inoculant survival on seed and inoculant establishment. Fertiliser application at oversowing consistently increased seedling and later plant size. Grazing managements (pre and post-oversowing), treading and chemical sward suppression effects were assessed on paddock scale oversowings of white clover into unimproved hill pastures. Pre-oversowing grazing to 900 kg DM/ha or less, and frequent post-oversowing grazings, were necessary to control competition from the resident sward. The use of paraquat: diquat at a low rate was required to maximise establishment. Reducing the water rate with herbicide from 200 to 60 litres/ha maintained high establishment on steep slopes and attained 80% of potential on easy slopes. Additional treading was a practical method of increasing establishment. Keywords: White clover, Trifolium repens, oversowing, establishment, rhizobia, competition, fertiliser, inoculation, pelleting, paraquat, diquat, treading, hill country.