兰州地区农田土壤速效磷与速效钾含量的变化特征

以兰州地区3县5区不同利用方式农田为研究对象,从作物种类、土地利用强度和耕作方式3个角度采集80个样点表层土壤样品(0—20cm),对其pH值、电导率、速效磷和速效钾进行了分析。结果表明:(1)兰州地区农田土壤pH值为8.59,蔬菜地pH值低于其它作物农田,但差异不显著。重度利用农田土壤pH值低于轻度和中度农田,日光温室农田pH值低于大田和砂田,但差异不显著。(2)土壤电导率具有较大的变异,变异系数高达107.31%,不同作物种类、利用强度及耕作方式下土壤电导率不具有显著差异性。(3)研究区土壤速效钾含量具有一致性,平均含量为362.65mg/kg,变异系数为48.81%,不同作物种类、不同土地利用强度和耕作方式土壤速效钾不具有显著差异性。(4)速效磷平均含量为14.07mg/kg,不同种类作物农田土壤中,蔬菜地速效磷高于其它种类作物;不同利用强度下,重度利用农田土壤速效磷高于中度和轻度农田;从耕作措施分析,日光温室农田土壤速效磷显著大于砂田和大田。研究表明,基于作物种类差异的不同土地利用方式及耕作措施对土壤酸碱性及速效磷含量具有不同程度的影响,集约型农业管理措施是导致速效磷含量增加的主要原因之一,且重度农田土壤有酸化的趋势。

Characteristics of Soil Available P and K of Farmland in Lanzhou Area

80 surface soil(0-20 cm) samples of different farmlands from 3 counties and 5 districts of Lanzhou City were investigated, and pH value, electrical conductivity(EC), available phosphorus and available potassium contents were analyzed according to crop species, intensity of land use and tillage method. The results showed that:(1) Average pH value was 8.59, and pH value in farmland where vegetables were grown tended to be lower than in other soils, but the differences were insignificant. Soil pH value in intensively used farmland was significantly lower than in moderately and slightly used farmland. Greenhouse soil pH value average tended to be lower than in traditional farmland and sand-covered fields, but it is not significantly.(2) There was a high variance in EC in the study area, and the coefficient of variance(C_v) was up to 107.31%. Differences of EC between different crop species, intensities of land use and tillage methods were all insignificant.(3) Soil available K showed in low variance, and the mean content and C_v was 362.65 mg/kg and 48.81%, respectively. The differences in available K were insignificant between different crop species, intensities of land use and tillage methods.(4) Mean content of soil available P was 14.07 mg/kg. Available P in farmland where vegetables were grown was higher than those in others. Sorted by land use intensity, available P was significantly higher in intensively used land soil than in moderately and slightly used soils. There was more available P in greenhouse soil than in sand-covered soil and traditionally used fields. The conclusion of this study was that crop species, land use intensity and tillage methods could affect pH value and available P content of farmland soil, and acidification and increase of available P content of soils may be mainly due to intensive management of farmland.