河南封丘县域农田土壤固碳速率空间变异特征及其影响因素

农田土壤固碳速率是评价土壤固碳效应和潜力的重要指标,精确估算区域农田土壤固碳速率对土壤地力及环境效应均具有重要意义.本研究选取黄淮海平原典型潮土区河南省封丘县为研究区域,按照土壤利用-土壤类型联合单元布点法,于2011年采集了70个耕层土样,测定了土壤有机碳含量、机械组成、容重、pH,并与全国第二次土壤普查(1981年)数据进行对比分析,结合地统计方法和GIS技术研究了该地区近30年农田土壤固碳速率的空间变异特征,利用显著性检验、回归分析、方差分析等方法定量分析了该区域农田土壤固碳速率的影响因素.结果表明: 近30年封丘县域土壤固碳速率平均值为0.33 t C·hm^-2·a^-1,变异系数为74%,属于中等变异性;土壤固碳速率的变化在东西方向上表现为西高东低、中部高南北低,呈片状分布,区域结构性因素是引起农田土壤固碳速率空间分布差异的主导因素,如土壤类型、机械组成、容重、pH,可解释空间变异的59.5%,其次是随机性因素,如秸秆还田量、施肥量,可解释空间变异的40.5%.

Spatial variability of soil organic carbon sequestration rate and its influencing factors in Fengqiu County,Henan, China.

Carbon sequestration rate in cropland soil is an important index to evaluate the effect and potential capacity of soil carbon sequestration. Accurate estimation of soil organic carbon sequestration rate is very important for studying cropland soil fertility and environmental effect. In this research, a typical fluvor-aquic soil area, Fengqiu County of Henan Province, located in Yellow Ri-ver basin of Huang-Huai-Hai Plain of China, was chosen as the study area. A total of 70 soil samples were collected according to combined unit grid method of soil utilization with soil type in 2011. The soil organic carbon content, soil mechanical composition, soil bulk density and pH were mea-sured, respectively. The spatial variability of the soil organic carbon sequestration rate of Fengqiu County in recent 30 years was also investigated by using geostatistics method and geography information system (GIS) technique, based on the comparative analysis of soil organic carbon content from samples surveyed in 2011 and the results surveyed by the 2nd state soil survey of China in 1981. In addition, the influencing factors of the soil carbon sequestration rate were quantitatively analyzed by statistical methods, such as significance testing, regression analysis and variance analysis. The results revealed that the soil organic carbon sequestration rate of recent 30 years was about 0.33 t C·hm^-2·a^-1 with a coefficient variance of 74%, which belonged to a medium variation. The spatial variability characteristics of soil organic carbon sequestration rate was of sheet distribution, which was higher in the west and lower in the east, and decreased from the central region to the south and north. The primary influencing factors of soil organic carbon sequestration rate were structural factors, such as soil type, mechanical composition, soil bulk density and pH, which could explain 59.5% of the spatial variability in the study area. The secondary factors were random factors, such as straw application and fertilizing amount, which could explain 40.5% of the spatial variability.