堆肥污泥连续施用对酸性砂土肥力影响及养分积累风险

Effects of Continuous Agricultural Application of Composted Sewage Sludge on the Fertility of Acidic Sandy Soil and the Risk of Nutrient Accumulation

为研究添加堆肥污泥对酸性砂土养分和肥力的影响,并探究污泥施用后的养分积累风险,本研究采用盆栽试验,通过施用不同量堆肥污泥,研究两年连续小麦-玉米轮作模式下酸性砂土养分和肥力变化规律,并利用有机指数(OI)和单因子标准指数(S;)分别针对砂土有机碳(OC)和全氮(TN)、全磷(TP)进行积累风险评价。结果表明,连续两年在酸性砂土上施用污泥提高了土壤的有机质、全氮、碱解氮、全磷、速效磷、有效钾含量、pH值和土壤综合肥力指数(IFI),均随污泥施用量的增加呈上升趋势。砂土中连续两年污泥施用,土壤有机指数(OI)等级表现为Ⅰ级清洁型,故污泥添加导致土壤有机碳的淋失风险较小;全氮的S;等级同样为Ⅰ级清洁型,而土壤全磷的S;在2017年小麦和玉米季污泥施用量为37.50 t·hm;时,达到Ⅱ级较清洁型,因此与氮素相比,污泥施用增加了砂土磷素淋失风险。可见,污泥农用可以改善酸性砂土的养分状况,但也需要注意污泥过量施用造成的养分积累风险。本研究结果为污泥在酸性砂土的合理施用提供了依据。

In order to study the effects of composted sewage sludge on nutrients and fertility of acid sandy soil, and to explore the risk of nutrient accumulation after sludge application, a pot experiment was carried out to study the changes of nutrients and fertility of acidic sand soil under wheat maize rotation for two years by applying different amounts of composted sewage sludge, and organic index(OI) and single factor standard index(S;) were used to evaluate the accumulation risk of soil organic carbon(OC), total nitrogen(TN) and total phosphorus(TP), respectively. The results showed that the pH value, organic matter, total nitrogen, alkali-hydrolyzable nitrogen, total phosphorus, available phosphorus, available potassium and soil integrated fertility index(IFI) of acidic sandy soil increased with the increase of sludge application rate for two consecutive years. The soil organic index(OI) level of acidic sandy soils was Grade Ⅰ clean type after two consecutive years of sludge application, thus the leaching risk of organic carbon caused by sludge addition was lower. The single factor standard index(S;) of total nitrogen was also Grade Ⅰ clean, while the single factor standard index(S;) of total phosphorus reached GradeⅡcleaner of sludge application rate was 37.50 t·hm;in wheat and maize seasons in 2017. Therefore, compared with nitrogen, sludge application increased the risk of phosphorus leaching from sandy soil. It can be seen that the application of sludge in acidic sandy soil is beneficial to improve its nutrients and soil fertility. On the other hand, attention should be paid to the increased risk of nutrient accumulation caused by excessive continuous application of sludge. So above results of this study provides a basis for the rational application of sludge in acid sandy soil.