Abstract: The purpose of this study was to research the suitable irrigation amount of alfalfa in Horqin sandy land. Alfalfa planted under the pointer-type sprinkler for two years was experiment material. According to the Penman-Monteith method recommended by the FAO,the actual water demand (ETc) of alfalfa was calculated in daily steps. The effects of different irrigation amount on alfalfa yield and water use efficiency in Horqin sandy land were studied based on the four irrigation levels of W1(60% ETc),W2(80% ETc),W3(100% ETc) and W4(120% ETc). The results showed that the profile distribution of available nutrients in soil was significantly affected by different irrigation quantities,and the accumulation peaks of alkaline nitrogen and available potassium were obvious. The residues of alkaline nitrogen and available potassium gradually decreased with the increase of irrigation amount. The residues of alkaline nitrogen and available potassium were the highest under W1 treatment. The leaching loss of alkaline nitrogen and available potassium gradually increased with the increase of irrigation amount. The leaching loss of alkaline nitrogen and available potassium was the largest under W4 treatment,and the available phosphorus was the largest under W2 treatment. 100% ETc irrigation level is recommended for irrigation during the growth period.

Key words: Alfalfa, Irrigation quantity, Available nutrients, Leaching loss, Residue

摘要： 为探讨科尔沁沙地紫花苜蓿（Medicago sativa L.）适宜灌溉量，本研究以指针式喷灌机下建植两年紫花苜蓿为试验材料，根据联合国粮农组织推荐的Penman-Monteith方法，以日为步长计算紫花苜蓿实际需水量（ETc），并基于ETc设置4个灌溉水平W1（60% ETc），W2（80% ETc），W3（100% ETc），W4（120% ETc），研究不同灌溉量对科尔沁沙地紫花苜蓿土壤速效养分分布、残留和淋失的影响。结果表明：不同灌溉量处理下，土壤速效养分剖面分部存在明显差异，碱解氮、速效钾出现明显累积峰；碱解氮、速效钾残留量随灌溉量增加逐渐降低，W1处理下碱解氮、有效磷、速效钾残留量最高；碱解氮、速效钾淋失量随灌溉量增加逐渐增加，W4处理下碱解氮、速效钾淋失量最大，W2处理下有效磷淋失量最大。综合比较各个处理，W3处理下土壤速效养分的残留量、淋失量结果优于其他处理，因此建议生育期内采用100% ET_c的灌溉水平进行灌溉。

关键词: 紫花苜蓿, 灌溉量, 速效养分, 淋失量, 残留量