Assessment of Influence of Alley Cropping System and Arbuscular Mycorrhizal (AM) Fungi on Cassava Productivity in Derived Savanna Zone of Nigeria

The dearth of fertile ‘virgin’ land and inaccessibility to standard chemical fertilizers, coupled with low tuber yields has made cassava cultivation unprofitable in parts of traditional cassava zone of West Africa. Field experiments were conducted at Ajibode and Alabata villages located in Ibadan (derived savanna zone), Nigeria to evaluate cassava (Manihot esculenta Crantz) root yield response to alley cropping species and arbuscular mycorrhizae fungi (AMF) inoculations. On farm trials were conducted during two growing seasons, in Rhodic Kandiustalf soil type with low nutrients. The alley cropping systems used Leuceana leucocephala and Senna siamea as hedgerow tree species (main blocks), while AMF inoculation (with or without Glomus clarum, G. mosseae, or G. fasciculatum) served as the subplots. Improved cassava cvs. TMS 30572 and TMS 91934 were intercropped within alleys. The leaf dry weight and cassava tuber yield were greatly enhanced by AMF inoculation, whether alley-cropped or sole-cropped in Ajibode fields. The positive contribution of mycorrhizae to cassava root yield ranged from 20.7 to 39.3%, depending on the treatment combination. However, in Alabata fields, out of four farms, cassava yield was suppressed in three of the farms by hedgerow trees. The suppression in yield was between 138.9 and 2.7%. However, the combination of the multipurpose trees and AM fungi greatly enhanced the cassava root yield (between 20.6 and 166.7%) even more than AMF inoculation alone. It is concluded that alley cropping system can bring about sustainable cassava production in the derived savanna agroecological zone if integrated gith efficient AMF. Due to favourable factors it is desirable to encourage adoption of the above improved technologies by resource poor farmers.