SummaryFlood irrigated date‐palm orchards annually manured for 10 (=U10), 50 (=U50, 110 (=U110) and 230 (U230) years together with a barren site in a nearby desert (=U0) all on sandy soils, were analysed for total P (TP), organic P (OP), inorganic P extracted by 0.5mH2SO4(Ca‐P), inorganic P not extracted by 0.5mH2SO4(NP), total N (TN) and organic C (TC). Watering resulted in continuing CaCO3accumulation in the soils. TC and TN to 160 cm depth increased rapidly over the first 50 years (120 g C m−2a−1and 9.7 g N m−2a−1), then the increases slowed. In contrast, TP continued to accumulate steadily (4.8 g P m−2a−1). AtU0, TP to 160 cm depth was very small (= 88 mg kg−1) and dominated by Ca‐P with OP as a minor component. AtU10, OP and Ca‐P were in equal proportions. The latter acquired increasing dominance with increasing period of treatment whereas OP reached a steady state. NP increased at a rate which decreased with time. It is likely that most of OP compounds have been leached down the profile where mineralization and subsequent immobilization, probably by Ca2+ions from irrigation
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机译：摘要对每年施肥 10 （=U10）、50 （=U50、110 （=U110） 和 230 （U230） 年的洪水灌溉枣椰果园以及附近沙漠中的贫瘠地点 （=U0） 均在沙质土壤上，分析了总磷 （TP）、有机磷 （OP）、0.5mH2SO4 提取的无机磷 （Ca-P）、0.5mH2SO4 未提取的无机磷、总氮 （TN） 和有机碳 （TC）。浇水导致土壤中CaCO3的持续积累。在最初的50年中，TC和TN深度为160 cm（120 g C m−2a−1和9.7 g N m−2a−1），然后增加速度减慢。相反，TP继续稳定积累（4.8 g P m−2a−1）。AtU0，TP到160 cm深度非常小（= 88 mg kg−1），以Ca-P为主，OP为次要成分。AtU10、OP和Ca-P的比例相等。后者随着治疗时间的增加而获得越来越大的优势，而OP则达到稳定状态。NP的增加速度随时间而降低。大多数OP化合物很可能已经浸出到矿化和随后固定的剖面上，可能是通过灌溉中的Ca2+离子
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