T.A. GIBSON1 and A.C. ANDREWS2
Thai Australian Highland Agricultural Project
University of Chiang Mai Thailand
1Faculty of Agriculture, University of Khon Kaen, Thailand.
2Department of Agronomy and Soil Science, University of New England, Armidale, 2351, Australia.
In the highlands of Northern Thailand, 15 percent of the forest vegetation above 1000 m has been converted to savanna grassland with a low carrying capacity. Forty pasture legumes and seventeen grass cultivars were tested with and without applied fertiliser at three sites of varying soil fertility, under lax and intensive cutting regimes.
Desmodium intortum cv. Greenleaf was the highest yielding and most persistent legume when fertiliser was applied. Stylosanthes guianensis was less responsive to fertiliser than D. intortum but equalled this species in the absence of fertiliser and gave the highest yields at the most infertile (low Ca and P) site. Moderate yields and good persistence were also achieved from Macrotyloma axillare and Trifolium semipilosum when sown in pure swards, fertilised and cut frequently. However, T. semipilosum and T. repens did not persist when sown with other tropical legumes or Paspalum species.
With grasses, highest yields and persistence were achieved from Setaria anceps (cv. Nandi and Kazungula), Brachiaria decumbens (cv. Basilisk) and Panicum maximum (cv. Hamil and Petrie). Paspalum dilatatum and Paspalum plicatulum (cv. Hartley) also persisted well but with lower yields of dry matter. Grasses were less responsive to fertiliser (excluding nitrogen) than the legumes.