Potential of Azolla Pinnata R. BR. green manure for enhancing production and nutritive value of Zea Mays L.

Abstract

We are faced with a challenge of meeting the food demands for the rapidly growing global population, yet the soils are becoming increasingly infertile. Climate smart agricultural technologies such as use of Azolla pinnata green manure is one of the promising options that can address low crop productivity as well as soil fertility depletion among resource constrained small scale farmers. This study therefore, aimed at assessing the effect of A. pinnata green manure on growth, yield, photosynthetic efficiency and nutritive value of Zea mays. The study sites were located in Luzira, Kampala District and Nsanvu, Luwero District where the experiment was laid out in a randomized complete block design with site as the blocking factor. The plots measured 25m by 10m while the sub plots measured 3m by 2m with six treatments replicated three times at each site. The treatments were 400, 300, 150 and 50 g of A. pinnata green manure and DAP applied to the soil per hole before planting and the control where no fertilizer was applied. All data were subjected to analysis of variance with means taken to be significantly different at 95% (p < 0.05). The results showed that application of A. pinnata green manure significantly increased plant height, number and weight of grains per cob, 1000 grain weight, cob length and diameter, leaf area, leaf area index, chlorophyll content, Phi2, crude protein and crude oil while it significantly reduced total carbohydrates and PhiNPQ as compared to the control. However, its application did not significantly affect crude fiber content in the Z. mays grains. The greatest height was recorded in the DAP treatment in Luzira while in Nsanvu it was in the 400g treatment but generally, the treatments resulted in better growth in Luzira than in Nsanvu. Similarly, the highest yields were got from Luzira although at both study sites 400 and 300 g A. pinnata green manure and DAP treatments gave the highest. From all parameters examined, the effect of 300 and 400 g A. pinnata green manure was comparable to that of the standard inorganic fertilizer DAP. Generally, treatment with A. pinnata green manure significantly enhanced the parameters investigated and this was attributed mainly to increase in nutrients in the soil after its mineralization. Therefore, the use of A. pinnata green manure at a rate of 300 g per hole is recommended to effectively substitute the inorganic fertilizers at planting in order to obtain high yields of nutritious Z. mays.