县域尺度作物产量和土壤有机碳密度时空变化及其相互关系

基于作物产量和表层(0~20 cm)土壤有机碳密度(SOCD)数据,利用GIS技术研究了县域尺度(青海乐都县)小麦产量时空变化特征及其与农田表层SOC关系。结果表明,乐都县小麦单产和SOCD在空间分布上具有显著区域特征,地形、土地利用方式等结构性因素影响SOCD和作物产量的相关关系。20世纪80年代和2000年以后,乐都县小麦单产与SOCD在空间上呈相反分布,高产区SOCD最低,低产区SOCD最高。这两个时间段,高产区小麦单产增幅仅为0.5%,SOCD增幅却达11.5%;中、低产区小麦单产均呈增加趋势,增幅分别为12.9%、18.9%,SOCD却呈降低趋势,降幅分别为24.6%、29.8%。

Spatio-temporal Variations and Interrelationships of Wheat Yield and Soil Organic Carbon Density at a County Scale

Soil property and plant growth exist spatial and temporal variations due to the unevenness of effects of natural and human factors across a region. This study investigated the spatio-temporal variations in wheat production and soil organic carbon density(SOCD) in surface soil(0~20 cm) at a county scale(Ledu, Qinghai Province). Wheat yield and SOCD had significant spatial patterns at county scale. However, they showed an opposite spatial distributions in the 1980s and 2000s:the lowest SOCD found in the high-yield fields and the highest SOCD observed in the low-yield fields. From the 1980s to the 2000s, wheat yield had a slight increase of only 0.5%, while SOCD increased by 11.5% in the high-yield fields; wheat yield was increased by 12.9%, but SOCD were decreased by 24.6% in the middle-yield fields; and wheat yield was elevated by 18.9% while SOCD were lowered by 29.8% in the low-yield fields. Topography and land use were the dominant factors influencing the relationships between SOCD and crop yields at county scale.