Potentials of Cassava Peels as a Soil Amendment: II. Field Evaluation
1985
Agbim, N. N.
The effect of cassava (Manihot esculenta Crantz) peels (CP), applied in different proportions with poultry droppings (PD) (chicken, Gallus gallus domesticus), on the growth of a root crop variously named cocoyam, taro, dasheen, and eddo [Colocasia esculenta (L.) Schott] was evaluated in the field over a 4-yr period, which included 1 yr of fallow. The treatments 100% CP-0% PD; 75% CP-25% PD; 50% CP-50% PD; 25% CP-75% PD; and 0% CP-100% PD were each applied at the rates of 0, 10, 25, and 50 Mg ha⁻¹. At 10 Mg ha⁻¹ the CP-PD mixtures increased yield by 559, 328, and 311%, respectively, for the 1979, 1980, and 1982 croppings, thus emphasizing the value of the amendment. Significant increases in yield (P < 0.01) were obtained each year for each increment in rate. The mean yields (Mg ha⁻¹) of 2.20, 5.09, and 2.40, respectively, for 1979, 1980, and 1982 demonstrate the residual benefit from these wastes after their incorporation into the soil. After 2 yr, treatment had no sustained effect on residual soil N. Residual (extractable) soil P increased from 11 mg kg⁻¹ with 100% CP to 89 mg kg⁻¹ with 75% CP-25% PD, thus showing the relatively low and high potentials, respectively, of CP and PD for increasing soil P. Since the availability of PD is considerably less than CP, a 75% CP-25% PD mixture at 25 Mg ha⁻¹ was deemed appropriate for most efficient utilization of the wastes. At 10 Mg ha⁻¹ of CP, total yield over 3 yr was also increased by 139%. With treatments containing PD, the corresponding yield increases were in the range 275 to 568%. Thus, while CP was a good soil amendment, there was need to incorporate PD with it to maximize yield.
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