摘要
了解土壤磷素积累特征对调控磷肥使用、降低农田磷素的环境风险和保障生态环境安全具有重要意义。以黄土高原沟壑区的典型小流域为对象,分析了18年来(1986~2004年)综合治理条件下流域土壤全磷、有效磷(Olsen-P)含量的时空变化特征及其对土壤水溶性磷含量变化的影响。结果表明,截至到2004年,流域磷素积累由塬面逐步向塬坡和沟道扩展。2004年,农田土壤全磷(752 mg·kg^-1)和Olsen-P(20.2 mg·kg^-1)较1986年分别提高了45%和3.5倍,相当于每年全磷提高13 mg P·kg^-1,Oslen-P每年提高1.0 mg·kg^-1,流域50%的农田土壤Olsen-P含量超过15 mg·kg^-1。与1993年大规模建立果园时相比,果园土壤全磷每年提高20~30 mg P·kg^-1,Olsen-P每年提高3~4 mg·kg^-1,2004年已有70%的果园土壤Olsen-P含量超过15 mg·kg^-1,20~60cm土层的果园全磷和Olsen-p含量也逐渐提高。但林草地的全磷没有显著变化,Olsen-P依然低于5.0 mg·kg^-1。1986年以来,无机磷肥的持续投入是流域土壤磷素积累的主导因素。流域土壤Olsen-P与全磷存在显著的线性相关关系(p〈0.001);水溶性磷与Olsen-P含量呈显著的指数函数关系(p〈0.001)。土壤磷素大量积累已成为黄土高原水土流失区当前十分迫切的农田环境问题。
Understanding soil phosphorus accumulation in environment plays an important role in control of phosphate fertilizer application,reduction in environmental risk and guarantee ecological environment security.Phosphorus application to agricultural soils in arable cropping systems and orchard systems often exceeds P uptake by crops and apple trees in the Loess Plateau,China.Taking a catchment as a model,we investigated changes in fertilizer P input,land uses,and fertilization practices in intensive farming systems from 1985 to 2004 in Wangdonggou catchment in the Loess Plateau.Soil total P(TSP),Olsen-P,and water soluble P(WSP) in soils were measured across landforms of the small catchment of Wangdonggou.For STP with more than 664 mg·kg-1 in the watershed,it accounted for 90% in tableland,50% in slopeland,and 38% in gullies,respectively.Some blocks in the tableland and slopeland were high P level with more than 900 g·kg^-1.For Olsen-P with more than 15 mg·kg^-1,it accounted for more than 87% in tableland,35% in slopeland,and 25% in gullies.The amount of inorganic P fertilizer added 2 t in 1985 into the catchment,increased to 16 t in 2004.The orchard area covered 2% of the total area in 1986,increased to 33% in 2004,cropland area decreased from 50% in 1985 to 28% in 2004.The increase of orchard area and P fertilization mainly contributed to P fertilizer input into the catchment,inorganic P fertilizer played an important role in P fertilizer input.The percentage of 65% in the P fertilizer added into the catchment was applied in orchard and 25% applied in crops in 2004.The area of Olsen-P with more than 15 mg·kg^-1 covered 50% of the cropland area and 70% of the orchard land area in 2004.In 2004,soil total P and Olsen-P in cropland soil were 752 mg·kg^-1 and 20.2 mg·kg^-1,respectively.The net total P accumulation in the cropland soil was 13 mg P·kg^-1 yr-1and the net Olsen-P accumulation 1.0 mg P·kg^-1 yr^-1.For the orchard land,the net total P accumulation ranged from 20 to 30 mg P·kg^-1 yr^-1and the n
出处
《自然资源学报》
CSCD
北大核心
2009年第7期1171-1180,共10页
Journal of Natural Resources
基金
国家重点基础研究发展计划(973计划)(2005CB121102)
国家自然科学基金(40771125)
中国科学院知识创新方向项目(KZCX2-YW-424)
关键词
小流域
土地利用
磷肥投入
土壤磷积累
small catchment
land use
fertilizer P input
P accumulation