不同利用方式对江西省农田土壤碳氮磷生态化学计量特征的影响

根据江西省2013年采集的16582个农田耕层(0～20 cm)土壤样点数据,运用实地调查、经典统计学与地统计学等相结合方法,研究了江西省耕地土壤碳氮磷生态化学计量特征的空间变异性及不同农田利用方式对其的影响.研究结果表明:江西省耕地土壤有机碳(SOC)、全氮(TN)和全磷(TP)平均含量分别为17.90、1.58和0.52 g·kg~(-1),土壤碳氮比(C∶N)、碳磷比(C∶P)和氮磷比(N∶P)平均值分别为11.72、38.29和3.38,土壤C∶N∶P比平均值为34.44∶3.03∶1,说明P是江西省耕地土壤主要的限制因素.此外,由于碳、氮、磷三者之间并不存在显著的两两相关性,表明江西省耕地土壤中不存在稳定的"Redfield ratio";半方差函数表明,江西省土壤碳、氮、磷生态化学计量特征具有中等程度的空间变异性,其空间变异特征主要受到随机性因素的影响;经ANOVA检验显示,不同农田利用方式对土壤碳氮磷生态化学计量特征影响显著(p0.05),土壤SOC和TN平均含量依次表现为:两季水田水旱轮作一季水田一季旱地两季旱地,土壤TP平均含量依次表现为:两季旱地两季水田一季水田一季旱地水旱轮作,土壤C∶N依次表现为:两季水田两季旱地一季水田水旱轮作一季旱地,土壤C∶P平均值依次表现为:水旱轮作两季水田一季水田一季旱地两季旱地,土壤N∶P平均值依次表现为:水旱轮作一季旱地两季水田一季水田两季旱地.总体而言,土壤碳、氮、磷生态化学计量比的变化特征是农田利用方式和环境因子综合作用的结果,土壤C∶N∶P比对土壤碳、氮、磷储量及养分的限制性具有重要的指示作用.

Effects of different land use types on ecological stoichiometry characteristics of Carbon, Nitrogen and Phosphorus in farmland soils in Jiangxi Province, China

Based on 16582 plow layer (0~20 cm) samples of farmland soil in Jiangxi Province, The spatial variability of ecological stoichiometry characteristics of soil carbon, nitrogen and phosphorus were studied through field survey, mathematical statistics analysis and Geo-statistics analysis methods. The results showed that:the averaged SOC, TN and TP contents were 17.90,1.58 and 0.52 g·kg^-1, respectively; the averaged values of C:N,C:P and N:P were 11.72, 38.29 and 3.38, respectively; and the average C:N:P ratio was 34.44:3.03:1, which indicated that farmland soils of Jiangxi Province were mainly affected by phosphorus. Pearson analysis showed no significant pairwise relationship was found between the three elements,which implied that there was no "Redfield"-type ratios in farmland soils of Jiangxi Province.The spatial variation of ecological stoichiometry characteristics of soil carbon, nitrogen and phosphorus were mainly caused by random factors according to semi-variance function analysis in Jiangxi Province. The One-Way ANOVA analysis results indicated that farmland use types showed a significant effect on C:N:P ecological stoichiometry characteristics(p<0.05). The order of SOC and TN was:double cropping paddy field > paddy-upland rotation > single cropping paddy field > single dry land > double dry land; the order of TP was:double dry land > double cropping paddy field > single cropping paddy field > single dry land > paddy-upland rotation; the order of C:N ratio was:double cropping paddy field > double dry land > single cropping paddy field > paddy-upland rotation > single dry land; the order of C:P ratio was:paddy-upland rotation > double cropping paddy field > single cropping paddy field > single dry land > double dry land; and the order of N:P ratio was:paddy-upland rotation > single dry land > double cropping paddy field > single cropping paddy field > double dry land. In general, the changes of ecological stoichiometry characteristics of soil carbon, nitrogen and phosphorus were mainly controlled by farmland use types and environmental factors. Soil C:N:P ratio had important indications for carbon, nitrogen and phosphorus storage and limited nutrient.