膜下秸秆还田添加腐解剂对旱地土壤碳氮积累及土壤肥力性状的影响

Effects of straw incorporation with decomposer and film mulched ridge furrow tillage on soil carbon and nitrogen accumulation and soil fertility characters in dryland, China

探索全膜双垄膜下秸秆还田添加腐解剂对旱地耕层土壤碳氮积累及土壤肥力性状的影响。2015-2017年在甘肃省农业科学院庄浪试验站,实施了以常规种植(CP)、常规种植+秸秆还田(CP S)、常规种植+秸秆还田+腐解剂(CP SD)、全膜双垄种植(FMRF)、全膜双垄种植+秸秆还田(FMRF S)和全膜双垄种植+秸秆还田+腐解剂(FMRF SD)为处理的田间定位试验。测定了耕层0~30 cm土壤有机质(SOM)、土壤全氮(TN)、全磷(TP)、全钾(TK)和速效氮(AN)、速效磷(AP)、速效钾(AK)、土壤容重(BD)和土壤pH,计算了耕层秸秆固存率(CSE)和碳氮积累量。结果表明,FMRF SD通过改善水热环境协同秸秆微生物腐解剂生产增效作用,加速了还田秸秆腐解与养分释放,产生的有机物抵消了土壤有机氮矿化损失,释放的养分补充了作物生长对土壤养分的消耗;改善后的水热肥条件又促进作物旺盛生长,使更多的有机物(落叶、根茬)回归土壤,从而显著促进了耕层SOC和TN的积累、提高了土壤TN、TP、TK和AN、AP、AK的含量,尤其是显著提高AP和AK的含量(P<0.05)。与CP比,FMRF SD 3年累计固存了41.17%的秸秆碳,耕层年均增加SOC和TN贮量0.79 mg C·hm^-2和0.04 mg N·hm^-2;使耕层TN、TP、TK和AN、AP、AK含量提高了0.05、0.03、3.05 g·kg^-1和10.80、8.90、101.50 mg·kg^-1,相应地增加了6.87%、6.94%、15.28%、10.24%、56.69%、55.34%。同时,FMRF SD使土壤BD和pH值分别降低了3.9%和0.2%。土壤碳氮贮量、氮磷钾养分含量的增加以及土壤BD和pH值的降低,增加了土壤供肥能力、改善了土壤结构和性状,从而显著提高了肥力。因此,FMRF SD是适合当地的最有效的农田碳氮库土壤肥力管理模式。

Full plastic film mulched ridge-furrow tillage(FMRF)and straw incorporation(S)are two effective strategies for managing soil fertility in semiarid areas.However,the effect of these two practices in combination(FMRF S)and the key mechanisms by which FMRF S positively modifies soil fertility characteristics,especially following application of cellulose-decomposing microbial cultures has not been well studied.To address this lack of information,a three-year field experiment with six treatments[conventional planting(CP),conventional planting with straw incorporation(CP S),conventional planting with straw incorporation plus decomposer(CP SD),FMRF,FMRF S,and full plastic film mulched ridge-furrow tillage with straw incorporation(FMRF SD)],and using a randomized block design with three replications,was conducted from 2015-2017.Soil organic matter(SOM),soil total and available nitrogen,phosphorus and potassium(TN,TP,TK and AN,AP,AK),soil bulk density(BD)and pH values of the 0-30 cm soil profile were examined.Soil organic carbon(SOC)content,SOC and TN accumulation as well as straw sequestration efficiency(CSE)were calculated.Results indicated that FMRF SD considerably accelerated SOC and TN accumulation in topsoil,significantly(P<0.05)increased the content of SOC,total and available N,P and K,especially the AP and AK content,in 0-30 cm soil profile,via enhanced straw decomposition and nutrient release that more than offset the loss of SOC by mineralization and replenished soil nutrients consumed by crop growth uptake,simultaneously enhancing crop growth and vigor,resulting in increased organic matter(litter and roots,etc.)returned to the soil to complement the soil nutrient reservoir through the synergistic effects of modified soil hydrothermal conditions and the added cellulose-decomposing microbial culture.Measurement results showed that,compared to CP,FMRF SD cumulatively sequestrated 41.17%of the straw carbon added over 3 years,which led to SOC and TN accumulation being increased by 0.79 mg C·ha^-1 and 0.04 mg N·ha^-1,respectively.This in turn increased the content of TN,TP and TK by 0.05,0.03 and 3.05 g·kg^-1,respectively,and the contents of AN,AP,and AK by 10.80,8.90 and 101.50 mg·kg^-1,respectively.These increases corresponded to elevations,respectively,of 6.87%,6.94%,15.28%,10.24%,56.69%,55.34%.In addition,the soil BD was lowered by 3.9%,and the soil pH by 0.004 units.With the increase of soil carbon and nitrogen storage,nitrogen,phosphorus and potassium nutrient content and the decrease of soil BD and pH values,the ability of soil to supply plant nutrients was increased,the soil structure and properties were improved,and thus the fertility was significantly improved.Therefore,FMRF SD is a highly effective management regime for improving soil carbon-nitrogen status and fertility characters in dryland.