|Prior, Stephen - Steve|
Submitted to: Journal of Sustainable Agriculture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/22/2007
Publication Date: 3/1/2008
Citation: Kang, H., Shannon, D.A., Prior, S.A., Arriaga, F.J. 2008. Hedgerow pruning effects on light interception, water relations and yield in alley cropped maize. Journal of Sustainable Agriculture. 31(4):115-137. Interpretive Summary: Alley cropping is a simultaneous and dynamic system wherein both crop and tree are continually changing in response to environmental conditions and management that affect both the trees and crops. A study was conducted to examine the effect of different pruning regimes on competition between mimosa hedgerows and corn in an alley cropping system in central Alabama. Findings suggests that pruning can increased light interception by corn and reduced the competition for water between maize and hedgerows. Hedgerow pruning increased corn biomass. Shading and water competition were most evident in the row closest to the hedgerows. This research demonstrates that with proper hedgerow management in alley cropping systems, it is possible to reduce competition for light and water and to decrease water stress in the crop, thereby increasing crop yield.
Technical Abstract: In alley cropping, trees and crops compete for light, nutrients and water. However, there was a paucity of information on how hedgerow pruning would impact light interception, water relations and yield in an alley cropped maize system. Competition between mimosa (Albizia julibrissin Durazz) hedgerows and maize (Zea mays L.) was measured under alley cropping in 2003 in Shorter, AL. Treatments were established in a randomized complete block design and consisted of no pruning or pruning at 30, 30+60 and 30+90 days after maize planting (DAP) and at 5 cm and 50 cm pruning heights. To minimize competition for nutrients, 189 kg N ha-1, 9 kg P ha-1, and 73 kg K ha-1 were applied. Reduction in photosynthetically active radiation (PAR) was assessed periodically. Water status in maize was assessed using a Steady State Porometer to measure maize leaf stomatal conductance and transpiration rate. PAR was lower in maize rows closest to hedgerows (ROW1) than in maize rows adjacent to ROW1 (ROW2) especially after 60 DAP. After the 90 DAP pruning, 30+90 DAP pruning treatment gave significantly lower stomatal conductance (CD) and transpiration rate (TR) in maize leaves than did 30 DAP or 30+60 DAP treatments. ROW1 had high CD and TR, which suggests water loss that might reduce final yields. Pruning increased PAR, maize grain and stover yields compared to no-pruning plots. Pruning twice gave higher grain and stover yields than did no-pruning controls. Pruning at 5 cm height gave higher maize yield than pruning at 50 cm. On average, ROW1 had 24% lower yield than did ROW2. Interaction of treatment by row was highly significant. Yield in ROW1 was more affected by pruning treatments than in ROW2. After 90 DAP, 30+90 DAP pruning treatment had lowest shade, followed by pruning treatment 30+60 DAP at 5 cm height. Pruning at 90 DAP and pruning at 5 cm height reduced competition for water and light. Hedgerow pruning can increase light interception and reduce water stress in the crop.