Competition between crops and weeds in the Zanderij area of Suriname
1991
Everaarts, A.P.
A weed flora rapidly built up with the cultivation of annual crops on two experimental farms in the Zanderij area of Suriname, despite the fact that the farms were newly established in forested areas. Studies indicated that without adequate weed control, significant yield losses occurred in groundnuts, sorghum and soybeans due to competition with weeds. Plant density of the crops was not affected, but competition with weeds reduced ground-cover and leaf area index. Competition affected growth rates, leading to lower yields. The nature of the competitive effects is discussed and data are presented on the spatial distribution of weed growth in the crops. To prevent yield reduction in groundnuts and soybeans, competition during the period of pod initiation should be avoided. In sorghum, competition must be prevented during the period of floret establishment. In groundnuts, a period of 15 weed-free days after planting prevented yield loss and the presence of too much weed at harvest. Yield losses in sorghum were prevented with about 20 weed-free days after planting. A period up to around 30 days was needed to attain negligible weed growth at harvest. It was necessary to weed soybeans up to around 30 days after planting to avoid yield loss and too much weed growth at maturity. The response of weeds to fertilizer application varied, depending on the weed vegetation and the nutrient applied. Both stimulation of growth and increase in weed density were observed. Band-placement of fertilizers in planter press wheel furrows considerably reduced weed growth when compared with broadcast fertilizers.
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