Alley cropping maize (Zea mays L.) and leucaena (Leucaena leucocephala Lam) in southern Nigeria

Summary

A maize-leucaena alley cropping system was studied on a N-deficient sandy Apomu soil series (Psammentic Usthorthent) at Ibadan in the forest zone of southern Nigeria from 1976 to 1980. In this system maize was grown in 4 m width alleys between Leucaena hedge rows.

Five to six annual prunings of the leucaena hedge rows yielded between 5 to 8 tons of dry tops/ha/year with N-yield of between 180 to 250 kg N/ha/year. Though efficiency of N utilization from leucaena prunings was low, the maize-leucaena alley cropping system can be utilized as a low N-input system. Addition of leucaena prunings from the full grown hedge rows, was able to sustain maize grain yield at about 3.8 tons/ha/year for two consecutive years with no N addition, while with no addition of prunings, yield declined. Higher maize grain yields were obtained with supplementation with low N rates of 20 to 80 kg N/ha depending on variety and season.

The maize-leucaena alley cropping system also has the potential for being developed as a stable alternative for the traditional bush fallow system. Leucaena plants which have unique properties suitable for growing in alley cropping, still retain important functions of a traditional bush fallow: for nutrient recycling, source of green manure, firewood, and staking material. Addition of leucaena prunings increased total soil N and organic C level.