Phosphorus dynamics and soil P-fertility constraints in Nepal

作者：Schreier H^*; Brown S; Lavkulich LM; Shah PB

来源：Soil Science, 1999, 164(5): 341-350.

DOI：10.1097/00010694-199905000-00006

• phosphorus sorption
• site factors
• Fe-Al chemistry
• spatial distribution
• P-Fe-Al interactions
• Nepal
• Middle Mountains

There are significant differences between the red and non-red soils in the Middle Mountains of Nepal, and inherent differences in the parent materials and soil management seem to have the greatest influence on fertility and P dynamics, The red soils with Munsell Hue color of 2.5 YR and 5 YR, were found to have higher P sorption capacity than the non-red soils (Hue 7.5-10 YR), and the Al(AAO) content was found to be the best predictive variable for P sorption. Using a 2 x 2 x 2 x 3 factorial design and GIS overlay techniques, a P-sorption map for a case study watershed was produced. The results may be used for determining where agricultural intensification with chemical fertilizer applications is most effective, The amorphous Fe and Al content is critical in determining P dynamics, and without high organic matter input, the red soils are highly deficient in available P, Management influences the P-sorption capacity in that the Al-(AAO) content decreased in irrigated red soils whereas the Fe-(AAO) content increased significantly. Irrigation reduces the amorphous Al content and this results in a 10 to 30% reduction in P sorption, Since most red soils are acidic and are deficient in carbon, the reduction of amorphous Al via irrigation has a positive effect on management by significantly reducing P sorption, The reducing conditions created by flood irrigation during the monsoon season and the addition of exchangeable bases from sediments and irrigation water increase pH values by up to 0.5 units and alter the amorphous Al and Fe content in these soils and, hence, P availability.

• 出版日期1999-5