Abstract
Effect of mycorrhizal inoculation and two pruning regimes in experimental alley cropping treatments on the leaf biomass and nutrient yield of sole and mixed Gliricidia sepium (a nodulating plant) and Senna siamea (a non-nodulating plant) were investigated both in the greenhouse and in the field. The impact of the mixtures of these legumes as hedgerows on maize and one cultivar of cassava was also studied in the field. Gliricidia sepium prunnings were found to have high nutrient yields, notably 358.4 kg ha-1 of N and 14.7 kg ha-1 of P as well as fast decomposition and nutrient release. In both Gliricidia and Senna, there were similar leaf dry matter values in sole and mixed inoculated or non-inoculated trees for either of the pruning regime and for most of the pruning harvests, although significant differences occurred between inoculated and non-inoculated mixed or sole trees. There was no difference between the total leaf dry matter of the 2- and 3-month pruning regimes in G. sepium. However, in contrast to G. sepium, the total leaf dry matter of the 2-month pruning regime of S. siamea was lower than its 3-month pruning regime, except for sole non-inoculated trees. Generally, inoculation and mixing of trees in the same hedgerows significantly increased the total N and P yield in G. sepium and S. siamea with greater values in the former than the latter. In G. sepium and except for mixed inoculated trees, while total N yield in the leaf was higher in 3-monthly pruned than 2-monthly pruned trees, the converse was the case for P. For S. siamea, the total N and P yields were higher in 3-monthly than 2-monthly pruned trees. Mycorrhizal inoculations consistently increased the yield of the cassava root tuber and maize grain over their non-inoculated counterparts.
