AbstractA drip irrigation system using porous plastic tubing was designed to study operational techniques of drip irrigation and fertilizer management in a highly weathered, leached, relatively low fertility, acid Oxisol. Sweet pepper (Capsicum annuum) was the test crop. All plots received an initial broadcast application of a 10-4.4-8.3 N-P-K fertilizer at the rate of 80 kg/ha. The experiment followed a randomized complete block layout with 4 treatments and 6 replications. The treatments were as follows: 1) N and K injected into the drip system, P banded; 2) banded N, P and K with drip irrigation; 3) broadcast N, P and K with drip irrigation; and 4) control-drip irrigation, no N, P and K other than the initial overall broadcast application. All treatments, except the control, received a total of 56.8 g of a 10-10-10 fertilizer per plant and all were uniformly drip irrigated according to pan evaporation data. Two crops were grown: one in the dry season and one in wet season. Yields were significantly different among all treatments for the dry season crop, with a high of 82.62 kg/ha for the treatments where Nand K were injected into the drip system and a low of 31.54 kg/ha for the control. For the wet season crop, no significant yield differences were found when fertilizer was injected into the drip system and when banded, but both these treatments were superior in yield to that of broadcast. These three treatments were superior to the control, with more than 100% increase. Drip irrigation is a promising alternative to currently used water-nutrient management methods for Oxisols in the wet-dry tropics.
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