Nutrient Management Strategies for Sloping Lands in Guizhou
IPNI-1999-CHN-GZ11
09 Jan 2009
2008 Annual Interpretive Summary
Effect of Cash Crop Hedgerows and Land Use Patterns on Soil Conservation of Sloping Lands in Guizhou, 2008
This ongoing study, initiated in 2004, continues to monitor various land use patterns, with or without established hedgerow crops, in order to select and extend optimal land use practices for sloping lands in Guizhou. Field experiments consisted of nine treatments including: alley cropping (corn-soybean-sweet potato-rape), grain crops interplanted with forage (corn-alfalfa), fruit trees (plum), engineered terraces with corn, cash crop hedgerow-1 (daylily+corn), cash crop hedgerow-2 (Polygonum cymosum Trev+plum tree+corn), grass (grass+chicory), arbor trees, and down-slope cultivation with corn.
Soil erosion and water run-off were highly positively correlated with rainfall quantity and negatively correlated with the degree of land coverage from the different land use patterns. Traditional down-slope cultivation with corn alone suffered from more severe soil and water losses than any other improved treatment in the study. The quantity of soil erosion ranged from 5 to 33.7 t/ha in the following treatment order: engineering terrace = arbor trees < hedgerow-1 = hedgerow-2 < grass ≈ grain crop interplanting forage < alley cropping < down-slope cultivation < bare land. Water losses as affected by treatment followed the same order as soil erosion. This order was somewhat different from past years, but farmer practice of down-slope cultivation and bare land were still the worst performers. Nutrient losses ranged from 2.8 to 9.3 kg/ha of available N, 0.06 to 1.0 kg/ha of available P, and 4.6 to 17.9 kg/ha of available K. Engineered terraces, hedgerow-1, hedgerow-2, and grass were most effective in reducing nutrient loss, while bare land, down-slope cultivation, and alley cropping were among the worst, particularly for available soil K and N losses. Most of the available soil N was lost through run-off water rather than through sediment loss, and the major form of available soil N lost was nitrate-N. Phosphorus loss in the sediment was generally higher than that found in run-off water, while the main loss of K was with run-off water.
As the woody species grow bigger, proliferating root systems spread out into treatment plots, and their canopies prevent light penetration to underlying crops, thus lowering yield potential. Woody species should be carefully selected if the farmland is planned for long-term cultivation of grain and oil crops. Guizhou-NMS03