Crop-hedgerow competition in an alley cropping system.

There was a reduction of light interception to the alley crops especially at the area closest to the hedge trees due to unpruned hedgerow canopy. There were no significant differences in soil chemical properties at 0.20 cm layer before and after the experiment irrespective of treatments except for the increase in pH and available phosphorus. The pruning interval and root barrier did not affect the soil chemical properties as well as soil content. The growth and biomass yield of Gliricidia sepium hedgerow in both dry and wet seasons were significantly higher with increasing hedgerow pruning interval. The highest biomass and dry matter yield were obtained at 90 days pruning interval in dry season and 60 days in wet season. However, root barrier reduced biomass production of hedge trees. The plant height, leaf area index, mungbean pod and grain yield, corn dry stover and fresh ear yield between with and without root barrier treatments did not differ significantly although a trend towards better performance of crops with root barrier treatments was evident. The growth and yield of mungbean and corn were significantly effected by row position relative to the hedgerow. The poorest performance of these alley crops was obtained at rows nearest to the hedgerow. Mungbean plant height in the rows close to the hedgerow was suppressed by 20-30 percent at both up and down side of hedgerow. The mungbean LAI was reduced by 20 percent. But only pod and grain yield of mungbean at the nearest row to the hedgerow downslope was significantly reduced by 32 percent. In the present study, the experimental area has a relatively fertile soil and high availability of soil moisture during cropping seasons. Therefore, the reduction of light interception caused by hedgerow canopy on the main crop was the main reason resulting for the poor performance of alley crop in rows close to the hedgerow.