Effects of length of pruning periods on the biomass yield of 'kakawate' as hedgerows in agroforestry

One of the most promising agroforestry technologies for upland development is alley cropping or hedgerow intercropping scheme. Alley cropping is one from of agroforestry that utilizes leguminous trees in establishing hedgerows along the contour of the slope to prevent erosion and to improve soil fertility. Alli et al. (WVSU) evaluated the above-ground biomass yield of 'kakawate' (Gliricidia sepium) as hedgerows in agroforestry system at different periods of pruning in Lambunao, Iloilo [Philippines]. Researchers hoped to specifically: 1) determine the fresh weight biomass of kakawate as well as its oven-dry weight biomass, and 2) determine the nitrogen, phosphorous, and organic matter content of dry biomass. The project was conducted from 2004 to 2007. Findings of the study revealed the following: Statistical analysis showed a significantly high difference on the total fresh weight of the kakawate harvested at 90 days compared with those harvested at 30 days and at 60 days. Results showed that a total biomass production of 4.25 t/ha was obtained when pruning was done after 90 days. This was higher compared to series pruning that was done at 30 days and yielded 1.54 t/ha. Statistical analysis for oven-dry weight of kakawate showed that there was a significantly high difference between those harvested at 90 days and those harvested at 30 days and 60 days. Meanwhile, weights for those harvested at 30 days and 60 days were 1.65 kg and 2.44 kg, respectively. The highest oven-dry weight of kakawate based on different cutting intervals was observed on kakawate harvested at 90 days. This was 0.960 t/ha. Results showed that at 90 days, the organic matter of kakawate was significantly higher than other treatments. This showed a result of 931.36 g. Results also revealed that at 90 days, the nitrogen and phosphorous contents of kakawate were higher compared with those harvested at 30 days and 60 days. The results were 44.54 g and 7.40 g, respectively. Researchers found that there was a significantly high difference on the rate of biomass production and mineral content when the pruning interval of kakawate was longer. More than half of the recommended nutrient requirements of cash crops planted in the area could be derived from harvested kakawate hedgerows. Thus, researchers highly recommend using kakawate as hedgerows in upland farms to improve soil fertility. They also recommended longer periods of pruning and several harvesting intensities. Further studies should also be done on periods of pruning using other species to come up with data on soil fertility and crop yield.