渭北旱塬苹果种植分区土壤水分特征

在区域尺度和定位观测的基础上，探讨了渭北塬区不同苹果种植分区的土壤水分特征．结果表明，渭北旱塬苹果种植分区土壤水分特征主要受降水和蒸散量的影响．在区域尺度上，苹果地潜在蒸散量是台塬东部区>高原沟壑区>台塬西部区．3种类型区苹果地土壤水分都存在亏缺现象，台塬东部区苹果地平均土壤水分亏缺量为390．9mm．最大亏缺量为674．6mm，最小亏缺量为186．3mm；高原沟壑区苹果地水分平均亏缺量、最大亏缺量分别为264．4和441．2mm，偶尔也出现水分盈余的现象；台塬西部区总体上表现为亏缺。但苹果地出现水分盈余的现象较高原沟壑区普遍，最大盈余量达151．8mm．渭北旱塬苹果地水分储存量也存在区域分异，在全生育期2m土层水分储存量台塬西部区>高原沟壑区>台塬东部区．这种变化特性与降水量的时空变化、果树对土壤水分的消耗量及降水年型有关；具体表现为苹果地耗水量以台塬东部区最大，高原沟壑区次之，台塬西部区最小，干旱年苹果全生育期耗水量低于丰水年．在干旱年份，苹果树耗水量除来源于生育期问的有效降水外，还有相当一部分依赖于3m以下土层贮水，形成土壤干层。影响果业持续发展．

Soil moisture characteristics of apple-planting subarea in Weibei dry highland,Shaanxi Province

Based on the data of regional scale and located field measurement,this paper investigated the soil moisture characteristics of the apple-planting subarea in Weibei dry highland,Shanxi Province.The results showed that the soil moisture characteristics in this subarea were affected by precipitation and evapotranspiration.At regional scale,the apple-land evapotranspiration in east Weibei area was the largest,and that in tableland gully and in west Weibei area was the medium and the smallest,respectively.Soil water deficit phenomenon was observed in three type areas.In east Weibei area,the mean water deficit amount was about 390.9 mm,the maximum was 674.6 mm,and the minimum value was 186.3 mm.In tableland gully area,the average and maximum values were 264.4 and 441.2 mm,respectively,and sometimes water surplus occurred.As a whole,soil moisture in west Weibei area was deficit,but the phenomena of water surplus were more prevalent than those in tableland gully area,and the maximum value was 151.8 mm.Soil moisture storage amount existed spatial and temporal variations in 3 different areas.The value of 2 m profile in apple growth season in west Weibei area was the largest,and that in Weibei tableland gully area and in Weibei east area was the medium and the smallest,respectively.The characteristics of soil moisture storage depended mainly on precipitation and its spatial-temporal distribution,as well as its consumed amount by apple trees.Water consumption in east Weibei area was the largest,the second was in gully area,and that in west Weibei area was the smallest.During apple growth season,the water consumption in dry year was less than that in wet year.In dry year,except for available precipitation,a considerable part of water used by apple trees came from deep (exceeded 3 m) soil moisture storage,which resulted in a dried soil layer and would affected the sustainable development of fruit production.