Production potential of cassava-based cropping systems

Abstract

A series of field experiments were conducted during the years 1983-84 and 1984-85 at College of Horticulture, Kerala Agricultural University, Trichur, to evaluate some of the cassava based intercropping systems and to investigate the interspecific interactions. There were three field trials and two micro plot trials. In the first field trial, the treatments were factorial combinations of two planing geometries of cassava viz., paired row and square cluster planting geometries of cassava viz., paired row and square cluster planting and four intercropping practices viz., intercropping with colocasia, elephant foot yam, banana and no intercropping. In the second field trial, there wer 12 treatments derived from the factorial combinations of three geometries of planting (paired row, square cluster and triangular cluster) and four intercropping practices (growing a floor crop of cowpea, groundnut, elephant foot yam and not growing any floor crop) in a cassava + banana intercropping system. In the third field trial, the possibility of growing two crops of groundnut in sequence ( Kharif and cowpea and/or Rabi) and the fertilizer requirements of intercrops were studied. All the three field trials were laid out in randomised Block Design and replicated thrice. In one of the micro-plot trials, 32P absorption by the component species in a cassava + banana + elephant foot yam cassava planted in square cluster was studied. polyculture with In the other micro plot trial 32P absorption by cassava and groundnut under the situations of cassava planted in paired row-ridge, mound and flat bed methods were studied. These two microplot trials were laid out in Completely Randomized Design with three replications. Paired row and square clustered planting of cassava gave similar yields as that of normal method when the plant population was the same. Intercropping cassava in square cluster with elephant foot yam resulted in maximum yield of cassava (20.1 t/ha) and elephant foot yam (10.6 t/ha). Banana and colocasia were also found to be successful as intercrops in cassava planted in paired row or square cluster. Intercropping with elephant foot yam and banana resulted in higher yield of cassava. The intercrops colocasia and elephant foot yam recorded lesser yields than the sole crops whereas in intercrop banana such difference was not observed. The maximum LER of 1.81 was obtained in cassava + banana cropping system. The cassava + elephant foot yam intercropping removed 133, 11, 107, 46, 12 and 18 kg/ha of N, P, K, Ca, Mg and S respectively wheras in the cassava + banana combination the corresponding figures were 227, 14, 236, 70, 16 and 11 kg/ha. From the two year trials, the cassava + banana + elephant foot yam cropping system with cassava planted in square cluster (9070 plants/ha) / triangular cluster (6800 plants/ha) was found to be the most productive and economical cropping system. Elephant foot yam was found to be shade tolerant and the yield reduction in intercropped situation was only marginal. The floor crops of cowpea and groundnut were successful in the first year. The land equivalent ratio in cassava + banana + elephant foot yam intercropping was 1.7 and this cropping system gave a net profit of Rs. 13300 per hectare. The N, P, K, Ca, Mg and S removal in a cassava + banana + elephant foot yam cropping system was found to be 198, 24, 200, 166, 34 and 19 kg/ha respectively. Sequential intercropping in paired row planted cassava was not successful, but growing groundnut and red gram simultaneously in the interspace was found to be successful; groundnut was harvested after four months, red gram after eight months and cassava after nine months. The fertilizer requirements of intercrop cowpea and groundnut were found to be only about 60-90 per cent of the sole crop recommendation and the optimum doses of N, P and K worked out were 6, 18 and 18 kg/ha for cowpea and 4, 30 and 30 kg/ha for groundnut. The main crop of cassava also was benefited by the application of fertilizers to the intercrops. The organic carbon and total nitrogen content of soil were reduced in two or three component intercropping systems by the two year cropping practices. The exchangeable P, K, Ca, Mg and SO 4 increased in situations where legmues alone were intercopped and decreased when banana and a floor crop of cowpea, groundnut or elephant foot yam were intercropped. The micronutrient status of the soil was not remarkably changed by the two season cropping. The intercrop and sole crop systems were not different in their influence on the post crop nutrient status of the soil. The radiophosphorus applied to the root zone of any of the components in the mixed cropping system cassava + banana + elephant foot yam with cassava in square cluster planting was absorbed not only by the treated plants but also by the surrounding species. Banana was the most dominant component in this polyculture. In the cassava + groundnut cropping system, cassava was the most dominant component, accumulating about 90 to 98 per cent of the 32P applied to cassava on mounds/ridges and about 50 percent of that applied to the groundnut root zone in the interspaces. Groundnut root system was small and less active and was able to derive only about 2 to 5 per cent of the 32P applied to cassava mounds. It was also deduced that the root interactions were stronger when all the components of the intercropping systems were a longer duration and it would be mild with legume intercrops of short duration.