Abstract: To lay a scientific basis for alfalfa soil testing and fertilizer recommendation in the Inner Mongolia Plateau (IMP) of China,the method of scattered experimental data integration and the new applied formula from a method of nutrient balance and target yield minus soil fertility yield were employed to study the rich-lack index(RLI) of soil N and the recommended N application rates (RNAR) for alfalfa in the natural regions. The results showed that the RLI of soil alkaline hydrolysis nitrogen for the first growing year alfalfa (FGYA) in the IMP of China for the 1^st to 6^th level were ≥ 48,20~48,8~20,4~8,2~4 and<2 mg·kg^-1,respectively. The RLI of soil total nitrogen for the FGYA for the 1^st to 5^th level were ≥1.4,0.8~1.4,0.4~0.8,0.2~0.4 and<0.2 g·kg^-1,respectively. The RLI of soil organic matter for the FGYA for the 1^st to 6^th level were ≥17,10~17,6~10,3~6,2~3 and<2 g·kg^-1,respectively. As the alfalfa target yield was 9~18 t·hm^-2 and the N fertilizer use efficiency was 40%,the RNAR of the 1^st to 6^th level soil for alfalfa were 0,68~135,135~270,203~405,270~540 and 338~675 kg·hm^-2,respectively.

Key words: Alfalfa, Soil testing and fertilizer recommendation, Alkaline hydrolysis nitrogen, Total nitrogen, Organic matter, Rich-lack index, Fertilizer application rate

摘要： 为了给内蒙古高原紫花苜蓿（Medicago sativa L.）测土施氮奠定科学基础，本研究采用“零散实验数据整合法”和“养分平衡-地力差减法”新应用公式，开展了该自然区域紫花苜蓿土壤氮素丰缺指标和推荐施氮量研究。结果表明：内蒙古高原生长第1年紫花苜蓿土壤碱解氮第1~6级丰缺指标为≥48，20~48，8~20，4~8，2~4和<2 mg·kg^-1，土壤全氮第1~5级丰缺指标为≥1.4，0.8~1.4，0.4~0.8，0.2~0.4和<0.2 g·kg^-1，土壤有机质第1~6级丰缺指标为≥17，10~17，6~10，3~6，2~3和<2 g·kg^-1。当紫花苜蓿目标产量9~18 t·hm^-2、氮肥利用率40%时，内蒙古高原紫花苜蓿第1~6级土壤推荐施氮量分别为0，68~135，135~270，203~405，270~540和338~675 kg·hm^-2。

关键词: 紫花苜蓿, 测土施肥, 碱解氮, 全氮, 有机质, 丰缺指标, 施肥量