江西省不同农田利用方式对土壤碳、氮和碳氮比的影响

基于江西省16582个农田耕层(0~20 cm)土壤样点数据,运用实地调查、数理统计与地统计学等分析方法,探讨了不同农田利用方式(水旱轮作、一季旱地、两季旱地、一季水田和两季水田)对土壤有机碳(SOC)、氮含量(TN)和碳氮比(C∶N)的影响.结果表明,江西省耕层土壤SOC、TN含量和C∶N比分别为5.22~34.56 g·kg~(-1)、0.26~3.06 g·kg~(-1)和2.98~52.67,均处于中等偏上水平.经半方差函数分析,江西省土壤SOC、TN和C∶N比的空间变异主要是由随机性因素引起的;方差分析显示,不同土地利用方式下耕地土壤中SOC、TN和C∶N比存在显著差异,土壤SOC和TN含量表现为两季水田水旱轮作一季水田一季旱地两季旱地,而土壤C∶N比则表现为两季水田两季旱地一季水田水旱轮作一季旱地,土壤C∶N比对估测区域土壤有机碳储量具有良好的指示作用,因此,从土壤C∶N比角度考虑,水田更有利于SOC的贮存,有利于增加土壤汇集碳氮的能力.Pearson相关性分析表明,5种利用方式下经度、纬度和海拔与土壤SOC、TN含量和C∶N比具有显著的相关关系.

Effects of different land use types on soil organic carbon, nitrogen and ratio of carbon to nitrogen in the plow layer of farmland soil in Jiangxi Province

Based on 16582 plow layer (0~20 cm) samples of farmland soil in Jiangxi Province, the effect of farmland use types (including paddy-upland rotation, single dry land, double dry land, single cropping paddy field and double cropping paddy field) on soil organic carbon (SOC), total nitrogen (TN) and ratio of carbon to nitrogen (C:N) and were studied through field survey, mathematical statistics analysis and Geo-statistics analysis methods. The results showed that the SOC, TN and C:N ratio were between 5.22~34.56 g·kg^-1, 0.26~3.06 g·kg^-1 and 2.98~52.67 respectively. The spatial variation of SOC, TN and C:N ratio in Jiangxi Province were mainly caused by random factors according to semivariance function analysis. The One-Way ANOVA analysis results indicated that the difference between SOC, TN and C:N ratio under different land uses was significant. The order of SOC and TN was:double cropping paddy field > paddy-upland rotation > single cropping paddy field > single dry land > double dry land, and the order of C:N ratio was:double cropping paddy field > double dry land > single cropping paddy field > paddy-upland rotation > single dry land. Soil C:N ratio is a good indication of estimating soil organic carbon storage in region.On the view of C:N ratio, paddy field was beneficial to increase the ability of collecting SOC and TN. In addition, the longitude, latitude, altitude had a very significant correlation with SOC,TN content and C:N ratio on the basis of Pearson coefficients analysis. Thus, longitude, latitude and altitude were the key factors to horizontal zonalityand vertical zonality for SOC, TN and C:N ratio in Jiangxi Province.