不同施肥对雷竹林渗漏水中可溶性有机碳、氮流失的影响

Effects of different fertilization treatments on loss of dissolved organic carbon and nitrogen in seepage water under phyllostachy pracox stand

【目的】雷竹(Phyllostachys praecox f.preveynalis)是一种在我国亚热带地区被广泛引种栽培的优良笋用竹。为了提高竹笋产量,农民不合理地大量施用化肥,已造成土壤盐化、酸化,地力破坏,导致土壤磷钾大量残留,特别是氮磷的大量流失已造成了周边水体严重污染。虽然土壤DOC和DON在土壤全碳、全氮含量中所占的比例很小,但却是土壤有机质中最重要和最活跃的部分。因此本研究的目的旨在通过全年动态监测雷竹林渗漏水中溶解性有机碳(DOC)和溶解性有机氮(DON)浓度的变化,探明减量施用化肥和有机肥对减少雷竹林氮渗漏淋失负荷的作用,以便为解决雷竹生产上的面源污染问题提供理论依据。【方法】试验设置了5个处理为对照(CK)、常规施肥(CF)、减量有机肥(DO)、减量无机肥(DI)和减量有机无机肥(DOI),3次重复,随机区组设计,小区面积为100 m2。试验于5月18日、9月7日、11月9日分别施用肥料总量的40%、30%和30%,施肥后均进行浅翻,深度5 cm左右。【结果】不同施肥雷竹林中DOC及DON平均浓度为33.7~45.5 mg/L和6.6~12.6 mg/L,DOC和DON的渗漏流失负荷为84.5~138.2 kg/hm2和17.2~46.3 kg/hm2。DOC渗漏流失负荷大小顺序为常规施肥(138.2 kg/hm2)】减量有机肥(133.7 kg/hm2)】减量无机肥(120.9 kg/hm2)】不施肥(99.8 kg/hm2)】减量有机无机肥(84.5 kg/hm2),而DON渗漏流失负荷大小顺序为减量有机肥(46.3 kg/hm2)】常规施肥(35.3 kg/hm2)】减量有机无机肥(34.8 kg/hm2)】减量无机肥(31.1 kg/hm2)】不施肥(17.2 kg/hm2)。渗漏水中DOC(mg/L)与DON(mg/L)之间不存在显著相关性。【结论】大幅减少化肥和有机肥用量,并推广有机肥和无机肥配施,不仅维持了雷竹竹笋的较高产量,还能减少土壤养分损失,具有经济和环境双重效益,是雷竹合理施肥的发展方向。

【Objectives】Lei bamboo( Phyllostachys praecox f. preveynalis) is an excellent variety for producing bamboo shoots and is widely distributed in the subtropical area of China. In order to improve yields of bamboo shoots,intensive management practices including over-application of chemical fertilizers have been adopted by the farmers. Although the farmers obtain great economic benefits,these practices bring out a serious new problems,such as bamboo grove degradation or even death,water system pollution,decline in soil quality and so on.Although the percentage of dissolved organic carbon( DOC) and organic nitrogen( DON) in soil was very low,they were sensitive for the change of soil environment. Change in DOC and DON concentrations in the seepage water from the soil under phyllostachy praecox stand in the whole year was monitored to ascertain the effects of reducingchemical and organic fertilizer rates on the concentrations of DOC and DON. 【Methods】Five treatments were designed: conventional fertilizer( CF),decreased organic fertilizer( DO),decreased inorganic fertilizer( DI),decreased organic and inorganic fertilizer( DOI),no fertilizer( CK). Fertilizers were separately applied in May 18,September 7 and November 9 with respective 40%,30% and 30% of total amount of fertilizer,and then plowed into soil at the depth of 5 cm. 【Results】The results showed that the average concentrations of DOC and DON in the seepage water for the different fertilization treatments were 33. 7- 45. 5 mg /L and 6. 6- 12. 6 mg /L,respectively,whereas the average seepage loss loads of DOC and DON for the different fertilization treatments were 84. 5- 138. 2kg /ha and 17. 2- 46. 3 kg /ha,respectively. The seepage loss loads of DOC from the soil with different fertilization treatments decreased as follows: CF( 138. 2 kg /ha) > DO( 133. 7 kg /ha) > DI( 120. 9 kg /ha) > CK( 99. 8kg /ha) > DOI( 84. 5 kg /ha),whereas the seepage loss loads of DON from the soil with different fertilization treatments decreased as follows: DO( 46. 3 kg /ha) > CF( 35. 3 kg /ha) > DOI( 34. 8 kg /ha) > DI( 31. 1 kg /ha)> CK( 17. 2 kg /ha). No significant relationship was found between DOC and DON concentrations in the seepage water. 【Conclusion】Decreasing inorganic fertilizer or decreasing organic fertilizer,and the combined application of organic and inorganic fertilizer,not only could keep the yield,but also play a remarkable role in reducing the loss loads of nutrient under Phyllostachy praecox stands suggesting that reducing inorganic fertilizer rate and applying organic fertilizer were the right direction for Phyllostachy praecox.