Spatial variation of soil organic matter in farmland from main grain growing regions of Xinzheng City, Henan Province

The content and variation of topsoil organic matter at township or villages unit in farmland from Xinzheng City, Henan Province, China were analyzed based on the data from field test site of local Chinese Ministry of Land Resources. The parameters were determined using the geostatistical trend analysis of ArcGIS10.0 and GS+9.0 with cross-validation methods. The unobserved soil organic matter (SOM) data was estimated by the ordinary Kriging method. The results showed that variability of township scale (24.49%) was less than that of villages (27.71%~28.70%) and the appropriate samples number were 100 and 1 000, respectively. Straw returning had great effects on SOM among different farmland management measures. The results suggested that it was appropriate to take soil sample at township scale than villages scale and straw returning to field played an important role to improve soil organic matter in farmland.