中国南方潴育性水稻土产量演变及其肥力驱动因素分析

系统分析了我国广西桂林、钦州及玉林3个潴育性水稻土长期常规施肥(F)和不施肥(CK)处理下,双季稻产量及土壤肥力随时间的变化趋势,并借助通径分析探明主要肥力因素对各点水稻产量的驱动差异和关联。结果显示,不施肥条件下,桂林点的基础地力较低,其产量随时间呈显著下降趋势(各季产量均值666~846 kg hm-2),而玉林和钦州点基础地力相对较高,其产量在试验期间相对稳定(各季产量均值3 500~4 577 kg hm-2)。常规施肥下,桂林点产量显著提高(较CK增产522%),且随时间呈显著上升趋势,另两试验点较CK增产20%~67%。常规施肥下,土壤肥力随时间呈稳定或不同程度的上升趋势,其中土壤有效磷初始值低于10 mg kg-1的桂林和钦州点上升幅度最大且均达到显著水平,而初始值为50 mg kg-1的玉林点变化不大。土壤有机质与全氮变化在各地不同,气温偏低的桂林点有机质呈上升趋势且全氮含量较高(3 g kg-1),气温偏高的玉林和钦州点有机质呈下降趋势且全氮含量较低(1~2.5 g kg-1),表明有机质的累积和释放上存在差异。双季稻产量的主要肥力驱动因子各地有差异,桂北地区桂林点土壤有效磷为首要因素,桂南地区玉林和钦州点土壤有机质及氮含量为主要的肥力因素。因此,依据区域特征采取有针对性措施是持续、高效培肥土壤的保证。

The rice yield trends in three hydragric paddy soils in south China and its fertility factors

A long-term (over 10 year) fertilization experiment on the double rice cropping system was conducted in three types of hydragric paddy soils in Guilin, Qinzhou and Yulin of Guangxi, South China to investigate variation of crop grain yield and soil fertility with time and differences between the three experimental sites in contribution of the major fertility factors to crop yield and relationship between the two using path analysis, The experiment was designed to have two treatments, CK (no fertilizer) and F (conventional fertilization). Results show that under Treatment CK, grain yield varied in the range of 666~846 kg ha-1, showing a significant decreasing trend with time at the site of Guilin where the basic soil fertility is rather low, but it was relatively stable, varying in the range of 3500~4577 kg ha-1, at the sites of Yulin and Qinzhou where the basic soil fertility is relatively high. However, under Treatment F it increased by 522% over that in Treatment CK, showing a significant rising trend at the site of Guilin, but at the sites of Yulin and Qinzhou, it did only by 20%~67%.. Soil fertility in Treatments F remained almost unchanged or increased to a varying extent. For instance, soil available P increased sharply to a significant extent at the sites of Guilin and Qinzhou where its initial value was lower than 10 mg kg-1, but it did not change much at the site of Yulin where its initial value was 50 mg kg-1. Soil organic matter and total nitrogen content also varied from site to site. Soil organic matter displayed a rising trend and TN content was high (>3 g kg-1) at the site of Guilin where the temperature is lower, while at the sites of Yulin and Qinzhou where the temperature is higher, the former displayed a declining trend and the latter was relatively low (1~2.5 g kg-1), showing differences between the sites in accumulation and release of soil organic matter. Differences between the sites in major fertility factor contributing rice yield were also observed. Soil available phosphorus is the primary factor at the site of Guilin while at the sites of Yulin and Qinzhou, soil organic matter and total nitrogen are. Therefore, taking proper measures in light of the soil properties of a region is a guarantee of sustainable effective soil building.