陕西洛川旱塬苹果园地深层土壤水分和养分特征

测定了陕西洛川旱塬11、15、20、25和43龄苹果园地0～1500 cm土层土壤湿度和0～300 cm土层土壤有机质、全氮、全磷、全钾、速效氮、速效磷、速效钾含量，分析了测定深度范围内土壤干燥化情况、各养分指标丰缺状况及其随种植年限和土层深度的变化特征.结果表明： 11、15、20、25和43龄苹果园地0～1500 cm土层土壤湿度依次为18.6%、13.7%、170％、11.5%和13.1%，随树龄增加果园土壤湿度总体呈降低趋势，有补灌果园土壤尚未发生干燥化，而旱作果园均发生了轻度或中度干燥化，0～300 cm土层土壤湿度高于麦田.0～300 cm土层土壤有机质、全氮和碱解氮含量分别小于10 g·kg^-1、0.75 g·kg^-1和50 mg·kg^-1，均处于亏缺状态；速效磷含量介于3.30～6.42 mg·kg^-1，总体表现为浅层适宜、深层亏缺状态，速效钾含量介于78.09～98.31 mg·kg^-1，尚未亏缺.果园0～100 cm土层有机质和氮、磷、钾含量均高于100～300 cm土层.随果树种植年限增加，土壤有机质、全氮、碱解氮含量及土壤养分指数（SNI）均表现为先增加后降低趋势；除全钾外，随土层深度增加，各养分含量在0～100 cm土层范围内快速降低，之后维持相对稳定.土壤有机质、全氮、碱解氮、全磷、速效磷和速效钾含量之间呈极显著正相关，而全钾与其他6个养分指标之间的相关性不显著.

Moisture and nutrient characteristics of deep layer soil in apple orchards on the Luochuan highland of Shaanxi, Northwest China

Taking the 11-, 15-, 20-, and 43 years old apple orchards on the Luochuan highland of Shaanxi, Northwest China as test objects, this paper measured the moisture content in 0-1500 cm soil layer and the organic matter and total and available nitrogen, phosphorous, and potassium contents in 0-300 cm soil layer, with the soil moisture and nutrient regimes as well as their variation characteristics with apple tree age and soil depth analyzed. The moisture content in 0-1500 cm soil layer in 11-, 15-, 20-, and 43 years old apple orchards was averagely 18.6%, 13.7%, 17.0%, 11.5%, and 13.1%, respectively, and decreased with apple tree age. Soil desiccation did not occurr in the orchards with supplementary irrigation, but a slight or medium soil desiccation occurred in the rainfed orchards. Nevertheless, the moisture content in 0-300 cm soil layer in the rainfed orchards was still higher than that in wheat field. The contents of organic matter and total and available nitrogen in 0-300 cm soil layer in the five apple orchards were less than 10 g·kg^-1, 0.75 g·kg^-1, and 50 mg·kg^-1, respectively, all at shortage level, whilst the content of available phosphorous in 0-300 cm soil layer was 3.30-6.42 mg·kg^-1, being moderate in upper soil layer and scarce in deep soil layer. The content of available potassium in 0-300 cm soil layer was 78.09-98.31 mg·kg^-1, presenting abundant. The contents of nutrients were all higher in 0-100 cm soil layer than in 100-300 cm soil layer. The soil organic matter and total and available nitrogen contents and the soil nutrient index (SNI) all presented a trend of decrease after an initial increase with the increasing apple tree age. The contents of the test nutrients except total potassium in 0-100 cm soil layer all decreased rapidly with soil depth, while those in deeper soil layers kept relatively stable. There existed significant correlations between the contents of soil organic matter, total nitrogen, available nitrogen, total phosphorous, available phosphorous, and available potassium, but no significant correlations between the contents of soil total potassium and other nutrient factors.