Weed suppression using vetch (Vicia sativa) as a cover crop in organically grown maize.

POGGIO, S.L., CEPEDA, S.A., ANDRIULO, A.

Durban, Sudáfrica

Congreso; 4th International Weed Science Congress; 2004

International Weed Science Society

The expansion of organic agriculture in the last decades have promoted the reintroduction of leguminous cover crops as a low input strategy for weed and resource management. The effects of different maize cropping systems on weed growth, crop yield, and nitrogen and water use were studied. An experiment was carried out at Pergamino (Argentina), including maize grown with organic (mechanical weed control and vetch cover crop) and conventional management (fertilization and herbicide application), and an unfertilised weedy control. Weed biomass of organic (21.5 g m-2) and conventional (29.7 g m-2) systems were significantly lower (P<0.05) than in the control (135.2 m-2). Consequently, yields of organic (1228 g m-2) and conventional (1101 g m-2) crops were higher than weedy crop yield (766 g m-2). Water consumed by maize did not differ among systems, suggesting that was not limitant. More nitrogen was returned as plant residuals in the organic (111 kg ha-1) than in the conventional system (89 kg ha-1), although nitrogen in both grain and total biomass did not differ between both systems. This could be attributed to a greater nitrogen mineralization due to soil disturbance from mechanical weed control, since the low vetch biomass (115 kg ha-1) suggest little N–fixing contribution. Present results remark the importance of leguminous cover crops to manage weeds and to improve resource use efficiency of field crops in low input agricultural systems, which require more research involving ecophysiological and agronomical factors.