28. Effects of groundnut, cowpea and melon on weed control and yields of intercropped cassava and maize.
Field Crops Research, 28, 1992, pp. 309-314
The objective of this study was to examine the effectiveness of groundnut, cowpea and melon as smother crops in the control of weeds in a cassava/maize mixture.
The traditional method used by peasant farmers to control weeds is hoeing, using household labour since hiring labour is expensive. For such farmers, use of herbicides is hampered by high cost and non-availability of chemicals. It is therefore imperative to find alternative methods of weed control acceptable to them.
Groundnut, cowpea and melon could serve as smother crops, help to reduce erosion, improve yield of crops, enhance the nutritional status of the growers' diet and bring additional income. Their ability to suppress weeds depends on cultivar, plant density, rate of growth and establishment of canopy cover, competitive ability, and fertility and moisture status of the soil.
The experiment discussed here consisted of three crops (Groundnut cv. DS 569, Cowpea cv. Ife Brown, and Melon cv. Western Local), each grown at two populations (20,000 and 40,000 plants ha-1) with cassava + maize intercrop together with controls of cassava + maize intercrop and sole crops of each species.
The results show that intercropping cassava and maize with 20,000 plants ha-1 of smother crops gave the best weed control, highest total yields and land equivalent ratio.
At the higher population, not only vegetative growth but also seed yields were reduced.
Of the three smother crops, groundnut gave the best weed control, followed by cowpea and melon, although the differences observed in the weed weight were not significant.
Yield of sole cassava was significantly higher than that of intercropped cassava in the early season. Generally, intercropping reduced yield of cassava with or without smother crops in both seasons. For maize, there was a general increase in intercrop yield over that of the sole crop when smother crops were included in the mixture in the late season. In the early season, maize yield increased only when 20,000 groundnut plants ha-1 were used as the smother crop.
Intercropping cassava and maize with smother crops improved the yields of both crops over when they were intercropped without smother crops.
This was probably due to better weed control achieved by the presence of the smother crops.
Further studies would be required to determine if such increases are due only to better weed control or also to better nutrient uptake or water conservation.
Considering only land-equivalent ratio (LER), there was a yield advantage in intercropping, and up to 55% and 104% more land would be required under sole crops to produce the yields achieved in mixtures in the early and late planting seasons, respectively.
Based on these results, 20,000 plants of groundnut, cowpea or melon ha-1 can be used as smother crop in cassava + maize mixture to give good weed control and high mixture yield.
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Africa, Ethiopia, weed control, intercropping, bean
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