The effect of preplant fertilization in the establishment of alfalfa-kikuyu grass intercropping in the Venezuelan Andes.
A kikuyu grass (Pennisetum clandestinum) sward was treated with herbicide and ploughed and harrowed once the grass had dried up, thus achieving an 85% reduction in grass coverage. After the cultivation treatment 150 kg/ha of anhydrous MgSO4 was applied. Four months after the herbicide treatment, the plots were oversown (on 23 Mar. 1990) with Medicago sativa cv. AS13 seed, inoculated with Rhizobium meliloti, in rows 20 cm apart, at a rate of 25 kg/ha. Two days before sowing the plots were given factorial combinations of 0, 160 or 320 kg N/ha, 0 or 160 kg P2O5/ha and 0 or 160 kg K2O/ha, or poultry manure at 0, 2, 4, 8 or 16 t/ha, or N:P:K at 160:160:160 kg/ha or double these rates with or without micronutrients (B, Cu, Zn, Mn, Co, Mo). Once established the plots were rotationally grazed with dairy cattle. Alfalfa yields in the establishment year accounted for 72% of total forage and showed a positive correlation with rates of poultry manure and N fertilizer application. Addition of micronutrients caused a marked increase in alfalfa yield with both levels of NPK but a decrease in kikuyu yield, especially at the higher NPK level.