2. Comparative evaluation of some inter-cropping systems in the humid tropics of southern nigeria.
Journal of Sustainable Agriculture, 2, (2), 1991, pp. 59-73
The present study was conducted to investigate the effects of intercropping maize with a mixture of melon and yam on soil moisture, soil temperature, rooting characteristics, and productivity of intercrop on an Ultisol in the humid tropical region of southern Nigeria.
Although much attention has been given to intercropping over the last two decades, there has been little research done on the effects of intercropping on soil moisture and temperature, particularly so in mixtures with more than two component crops. Traditionally, farmers in southern Nigeria would grow five or more annual and perennial crops simultaneously.
Field experiments were conducted near Benin City, southern Nigeria.
Before the initiation of the present trial, field plots were under no tillage for 2 years and, therefore, the same system was followed for this investigation also. Three plots, each measuring 30 x 60 m, were marked for intercrop and nine plots, each measuring 8 x 30 m, for sole crops. The intercrop treatment comprised maize, melon and yam. Local cultivars of yam and melon, grown by farmers of the region, were grown for these experiments. Yam sets, weighing 200 to 250 g each, were planted at 1 x 1 m spacings. Melon was planted at 0.5 x 1 m spacings in the yam rows so that there were two melon plants between a pair of yam plants. Maize (cv. TZSR-W in 1987 and TZSR-Y in 1988) was planted between yam + melon rows at 0.3 x 1 m spacings. Planting of crops at a given spacing was carried out on the same day in the intercrop and monoculture plots. After planting, 400 kg ha-1 of 15:15:15 NPK mixture fertilizer was carefully spread on the maize rows alone. One month later, the second dose of N (60 kg ha-1) as calcium ammonium nitrate was side-dressed to maize after thinning to one plant per hill. About 2 months after germination, yam vines were supported with wooden stakes over 3 m long.
At 0.10 m depth, the soil was desiccated most under the intercrop compared with monocrops. The trend changed at 0.30 m depth where minimum soil water was under sole maize. At 0.01 depth, maximum soil temperature in the intercrop was lower by 1-2, 8-10 and 8-11 C in relation to monocultures of melon, yam and maize, respectively, depending on insolation load and soil moisture content. At 0.20 m depth, however, temperature differences between intercrop and monocrops were much smaller due to soil's damping effect. Intercropping decreased plant height and leaf area index of maize as compared to monocropping. Maize root length density in the 0-5 cm layer under the row was lower in the intercrop than sole crop, but in the 10-20 cm layer this was reversed.
The intercrop of maize, melon and yam produced 61 and 98% more food than monocrops in 1987 and 1988, respectively, as assessed by area x time equivalent ratio.
The intercrop was more productive in terms of food production per unit area than the monocultures as indicated by the values of LER. For example, intercropping produced 130 and 167% more food per unit land area than component monocultures in 1987 and 1988, respectively. LER does not take into account the growth periods of crops and is considered an inappropriate index for evaluating the potential productivity of a mixture consisting of crops of widely different maturity periods. The point is that if long duration crops (yams in the present study) had not been grown, two crops of shorter duration, e.g., maize or melon, could have been taken in a year. The ATER was 1.61 and 1.98 in 1987 and 1988, respectively. This index confirms the earlier conclusion drawn by LER that productivity of the intercrop was higher than monocultures per unit area but not as high as is indicated by LER.
1092 92 - 4/135
Latin America, Colombia, study, intercropping, land-use efficiency, cassava, maize, yam, yield performance
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