Effect of cowpea living mulch on soil quality and maize grain yield in northern Ghana
Nurudeen Abdul Rahman1, Asamoah Larbi2, Albert Berdjour1, Fred Kizito1, Irmgard Hoeschle-Zeledon3
1International Institute of Tropical Agriculture (IITA), Ghana
Low soil fertility is a major constraint for maize production in West Africa and the use of legumes as living mulch improves soil fertility and yield of main crops. However, there is limited literature on the appropriate time to plant living mulch in maize-based cropping system in West Africa. A 2-year (2017-2018) study was conducted to determine the effect of cowpea living mulch (CPLM) on soil quality and grain yield of maize in northern Ghana. A 3 × 4 factorial treatment combination of maize maturity types and CPLM was laid-out in a randomised complete block design with 4 replications in Northern and Upper East regions of Ghana. The maize maturity types were extra-early; Abontem, early; Omankwa and medium; Obatanpa. The CPLM included control (farmer practice), CPLM with maize planted on the same day, CPLM planted at 1-week after maize and CPLM planted at 2-weeks after maize. Principal component and correlation matrix analyses were used to select minimum data set for soil quality index (SQI) calculation. The SQI for CPLM improved by 50-100% compared with that of the farmer practice during 2017 and 2018 in both locations. The CPLM significantly increased maize grain by 34-37% relative to the farmer practice during 2017 and 2018 in Northern Region. In Upper East Region, the grain yield for CPLM was 84% higher (p < 0.01) than that of the farmer practice during 2017 but the grain yield decreased with CPLM relative to that of farmer practice during 2018. Maize maturity types affected (p < 0.05) grain yield during 2017 in Northern Region but did not show significant effect on grain yield during 2018 and both years in the Upper East Region. The results suggest that smallholder maize-based farmers in northern Ghana and similar agro-ecologies in West Africa can intercrop cowpea as living mulch especially at 1-2 weeks after planting maize to improve soil quality and increase maize grain yield. Depending on the calendar days of the cropping season in northern Ghana, smallholder maize farmers can plant the different maize maturity types particularly the early maturing type for better and stable yields.
Keywords: Cowpea, living mulch, maize, savannah, smallholder farmers, soil quality
Contact Address: Nurudeen Abdul Rahman, International Institute of Tropical Agriculture (IITA), Education Ridge, 0233 Tamale, Ghana, e-mail: a.nurudeencgiar.org