ROLE OF PIGEON PEA IN MAIZE FARMING SYSTEMS AND SOIL FERTILITY MANAGEMENT IN KILIFI COUNTY
MWAJOHA, HUMPHREY ALLAN
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Soil fertility improvement and maintenance is constrained by high cost and low adoption of inorganic fertilizers in Coastal region. About 10% of the farmers in the Coastal region of Kenya using chemical fertilizers apply suboptimal rates due to financial constraint. Diversifying farming systems through intercropping cereals and legumes can contribute to soil fertility improvement leading to high yields and land productivity. The general objective of the study was to increase maize yields through an innovative soil fertility management system towards enhancing food security. Specific objectives were: (1) To determine the effect of pigeon pea on growth and yield of maize in a maize-pigeon pea intercropping system; (2) to determine the effect of maize on growth and yield of pigeon pea in a maize-pigeon pea intercropping system; (3) to determine the changes in nitrogen, phosphorus and pH in the soil due to maize-pigeon pea intercrop; (4) to investigate the effect of di-ammonium phosphate (DAP) fertilizer on growth and yield of maize and pigeon pea in a maize–pigeon pea intercrop; (5) to determine the land equivalent ratio of a maize–pigeon pea intercrop. Two pigeon varieties (short and medium maturing) and one maize variety (PH4) were used in the study. The experiment was laid out in a randomized complete block design replicated thrice. Data collected on maize included plant height, number of cobs, ear height and grain yield while for pigeon pea included plant height, grain yield and biomass. Soil samples were analyzed to determine the increase in nitrogen, phosphorus and soil pH in the soil due to inclusion of pigeon pea in the intercropping system. The grain yield of maize and pigeon pea were used to determine land equivalent ratio of the intercrop. The data collected was subjected to analysis of variance using SAS statistical software (SAS Institute, 2003) and means separated using least significant difference (LSD) at P ≤ 0.05. The results showed that location had no significant effect on maize and pigeon pea intercropping system. Intercropping maize with pigeon pea had vi no significant effect (P ≤ 0.05) on maize grain yield. The tallest maize plants were observed in treatments where maize and medium duration pigeon pea were planted in alternating rows, two weeks after maize planting with fertilizer, whereas the highest grain yield and number of cobs was observed in treatments where maize and short duration pigeon pea were planted in the same hole at the same time with fertilizer. The intercropping system had no effect (P ≤ 0.05) on the height and grain yield of pigeon peas. However, higher pigeon pea grain yield was observed in the monocrop as opposed to the intercropping systems. The most suitable pigeon pea variety was the short duration pigeon pea which produced grain as well as high amounts of biomass. The addition of diammonium phosphate fertilizer led to enhanced growth and yield in maize as opposed to that of pigeon pea. Most of the intercropping system treatment combinations had a land equivalent ratio of more than one (LER > 1) an indication that intercropping was more advantageous than sole crop. Soil analysis results indicated that maize and medium duration pigeon pea intercropped in alternating rows at the same time with fertilizer; and maize and short duration pigeon pea intercropped in the same hole two weeks after maize planting with fertilizer had highest capacity of enhancing availability of soil nitrogen and phosphorous respectively. The results from the study therefore indicate that pigeon peamaize intercropping system within the Coastal lowland zone 3 (CL3) is feasible for the small scale farmer.