Effect of Spatial Arrangement on Yield and Resource Efficiency of Maize-Sweetpotato Intercrop in a Midland Agro-Ecology of Embu, Kenya

Abstract

Food and nutrition insecurity remains a challenge in Kenya, and diversifying maize-based systems is key to resilience. This study evaluated the productivity and resource-use efficiency of maize–sweetpotato intercrops under varying spatial arrangements in Embu County, Kenya Planting for the first season was done in October 2023 and harvesting done in April 2024 and for the second season planting was done in May 2024 and harvested in October 2024. Farmer-managed trials were conducted at four mid-altitude sites Manyatta Sub County (Mbeti North Ward and Kirimari Ward) and in Runyenjes Sub County (Kagaari North Ward and Runyenjes Central Ward). Treatments included sole maize, sole sweetpotato (varieties Irene and KEMB10), and six intercrop configurations alternating 2 or 4 rows of maize with 2 or 4 rows of sweetpotato, testing both equal and unequal row proportions. Data on maize (plant height, cob traits grain yield and biomass) and sweetpotato (marketable, non-marketable roots and root yields) were analyzed using ANOVA in SAS (p < 0.05). Cropping efficiency was assessed using Land equivalent ratio (LER), land equivalent coefficient, system productivity index (SPI), and maize equivalent yield (MEY). Sole maize produced the highest biomass (3.1–5.0 t/ha). The intercrop of 2 maize rows with 4 sweetpotato rows recorded the highest LER (1.53–1.56), SPI (3.5–3.6), MEY (5689–5258kg/ha), and net income (US$1736 for Irene; US$1572 for KEMB10). Sole sweetpotato yielded the highest root yields (7.6 t/ha for Irene, 12.1 t/ha for KEMB10), while intercrops balanced root and grain yields. The 2:4 maize: sweetpotato intercrop with Irene offered the best balance of yield, efficiency, and profitability, making it a suitable option for farmers aiming to maximize returns on limited land. For resource-constrained farmers, the 2:2 arrangement provides a lower-cost yet economically viable alternative, supporting broader adoption of intercropping for food and income security.