Abstract:
Gliricidia sepium is a fast growing legume shrub or tree with a wide range of environmental adaptation. Pruning of bushes at 1 m tall provides a source of crop nutrients. However, the value of pruning for increased agricultural productivity is not fully known. A study was carried out in a high rainfall humid tropical environment to investigate the contribution of Gliricidia sepium prunings (leaves and roots) and subsequent fallow with prunings to nitrogen (N) release pattern, sweet corn yield, nitrogen uptake and the N use efficiency (NUE) of the prunings. 15N atom excess dilution and litter bag incubation techniques were used to partition N uptake and estimate N-release pattern of the leaves and roots. The prunings were applied as smooth stems and leaves at a rate of 120 kg N/ha in two split applications, 7–30 days after sweet corn germination. The crop was harvested after 75 days at the physiological maturity. The results showed that Gliricidia Sepium leaves and roots significantly (p ≤ 0.05) increased sweet corn dry matter yield (3158 kg/ha) over the control (898 kg/ha). However, this was not significantly different from those treatments with leaf or root prunings in the presence of hedgerows. Use of root prunings as fallow showed significantly (p ≤ 0.05) higher sweet corn dry matter (2175 kg/ha) yield than that (1082 kg/ha) obtained from leaf prunings application. Nitrogen partition using 15N atom excess dilution showed that Gliricidia sepium fallow and leaf prunings contributed 25.9% and over 100% of total sweet corn N uptake and yield (as total dry matter), respectively. The incubation experiment showed that Gliricidia sepium leaves mineralize very fast, faster than roots, and should be re-applied within 20 days to maintain N-supply from the leaf prunings. It was concluded that Gliricidia sepium pruning and fallow contribute to the N uptake, growth and yield of the sweet corn with 5–9% NUE of the prunings. Further research is required to increase N use efficiency of Gliricidia sepium prunings and fallow in this study environment.
