Mulching is one successful weed-control method, but the practice competes with household food needs and does not provide additional income to growers in the rainforest where farm size is small and space is intensively utilized in complex cropping systems.
Dr. J.C. Obiefuna, and his co-workers at the School of Agriculture and Agricultural Technology in Owerri, Nigeria, became interested in this problem and sought a potential solution by intercropping the plantains with a fast, low-growing plant to curb weed growth. The plant they chose was the Egusi melon, Colocynthis citrullus , a popular crop in Nigeria for its dietary and economic importance. The Egusi melon is a fast spreading creeper which provides effective weed suppression in traditional mixed planting with staple crops such as yam, maize and cassava. After harvesting the melons, which mature in just 3 months, the plant residue can be applied to the base of plantains as a mulch to improve soil fertility through its high residual nitrogen content*.
Trial plots were planted at the University research farm at Owerri (latitude 5°27’N — longitude 7°02’E, in a tropical rainforest zone) during an early cropping season in March. The test site was a field which had been in fallow for 3 years, and was slashed, burned, plowed and harrowed. The soil was a sandy loam ultisol. The plantains were prepared and dressed with 3G furadan to control plantain weevils and nematodes.
Twenty-five plantains were sown in each plot, at 2.5 X 2.5m spacing in holes 40cm wide and 30cm deep. Melons were planted between the rows on the same day as plantains at the rate of 3 seeds/hill and later thinned to one. The plantains received nitrogen (320 kg/ha) potassium (from 60% K2O) and phosphorus (160 kg/ha). The intercropped melons were planted at three different densities: 2,500, 5,000, and 10,000plants/ha. Weeding was delayed for 3, 5 and 7 months, respectively, after planting. Weed coverage was sampled from 1m2 quadrats before each weeding. The weeds were dried in an oven at at 60°C for 48 hours to determine their dry weight.
Melons planted at the highest density(10,000 melons/ha) rapidly covered the ground in 20 days and effectively suppressed weed competition for 7 months after planting. Those planted at 5,000/ha were equally effective at suppressing weeds, and even accelerated plantain growth. At the low melon density surface cover was poor at 40 days after planting. The resulting weed population became increasingly severe—doubling before weeding at 5 months, and tripling before 7 months.
The most beneficial intercropping density in this study was 5,000 melons/ha. At this density the melons effectively checked initial weed growth while permitting the plantains to develope enough shade canopy to prevent severe weed growth and competion after the melon harvest. A weed-free plantain orchard was continuously maintained together with the increased plantain yield under the 5,000 melon/ha experiment. The melon cover, as a mulch further enhanced the system nutrient supply and microbial activity resulting from the decomposition of the cover crop. Soil moisture and temperature were improved, benefiting plantain production. Farmers with perennial crops could use this idea and adapt it to their conditions and cropping patterns.
Mba, C.C. (1983). Egusi plant-Colocynthis citrullus and soil properties. Paper presented at the 6th Annual Conference of Horticultural Society of Nigeria, University of Nigeria, Nsukka, 1983, p.5.
For more informations contact:
Dr. J.C. Obiefuna
School of Agriculture and Technology
Federal Universty of Teaching
P.M.B. 1526, Owerri NIGERIA
Dr. J.C. Obiefuna