秸秆还田方式对草甸土有机碳和硝态氮分布特征的影响

1、    秸秆还田方式对草甸土有机碳和硝态氮分布特征的影响    李玉梅王根林刘峥宇张冬梅李艳蔡姗姗摘要  目的研究不同耕法與秸秆还田方式下草甸土不同深度土层中有机碳（soc）和硝态氮（n）的分布特征，为有效利用秸秆培肥土壤提供依据。方法采用田间定位试验，研究3种耕法（免耕、浅翻、深翻）与3种秸秆还田方式（覆盖还田、浅翻还田、深翻还田）条件下，不同时期、不同深度土层中soc与硝态n的变化。结果无论秸秆是否还田，不同耕法下土壤硝态n含量随生育进程均表现为先升高再降低的趋势，苗期>成熟期>播种期;无秸秆还田条件下，3种耕法处理土壤硝态n含

2、量随土层深度增加而降低，4050 cm土层均没有出现硝态n富集现象，浅翻与深翻分别对1020和2030 cm土层硝态n含量影响较明显;深翻处理030 cm土层soc含量比免耕和浅翻分别降低8.75%、9.53%;秸秆还田条件下，不同时期土壤硝态n总积累量不同。苗期以深翻还田处理积累量较大，比浅翻还田和免耕覆盖分别增加8.15和9.57 mg/kg;成熟期硝态n总积累量以免耕覆盖处理最大，比浅翻还田和深翻还田分别提高19.23%和14.68%;深翻还田3040 cm土层soc含量比免耕覆盖和浅翻还田分别增加3.33和3.86 g/kg。结论同一耕法，短期内连续有秸秆还田处理土壤硝态n含量低于无秸

3、秆还田处理，秸秆还田深度影响不同深度土层中soc的含量。关键词  草甸土;秸秆还田;有机碳;硝态n;分布特征  s-3;s158.2      a  0517-6611（2019）24-0063-04doi：10.3969/j.issn.0517-6611.2019.24.021effects of straw returning methods on distribution characteristics of organic carbon and nitrate-n in meadow soilli yu-mei1，

4、wang gen-lin2， liu zheng-yu3 et al（1.institute of soil fertility and environmental resources，heilongjiang academy of agricultural sciences，harbin，heilongjiang 150086;2.institute of animal husbanbry of heilongjiang academy of agricultural sciences，harbin，heilongjiang 150086;3.heilongjiang suibin farm

5、， suibin，heilongjiang 154213）abstract  objectivethe research aimed to study the distribution characteristics of organic carbon （soc） and nitrate nitrogen （n） in different depths of meadow soil under different tillage methods and straw returning methods， and provide a basis for effective use of

6、straw to fertilize soil.methodfield positioning experiment was conducted to study the changes of soc and nitrate-n in soil layers of different periods and depths under the conditions of three kinds of tillage methods （no-tillage， shallow tillage， deep tillage） and three kinds of straw returning meth

7、ods（covering returning fields， shallow tillage turning field， deep tillage turning field）.resultthe trend of soil nitrate-n content was increased first then decreased with the growth process whether the straw was returned to the field， seedling stage>maturation period> sowing date.the soil nit

8、rate-n distribution under three kinds of tillage was decreased with the depth of soil layer decreasing without straw， and there was no nitrate-n enrichment in 40-50 cm soil layer in the short term， at the same time the nitrate-n content in 10-20 cm and 20-30 cm soil layers was respectively influence

9、d by shallow tillage and deep tillage.the soc content was effected at deep tillage in 0-30 cm soil layer， which was lower 8.75% and 9.53% than that in no-tillage and shallow tillage.after the straw was returned to soil， the total accumulation of soil nitrate n in different periods was different.in t

10、he seedling stage， the accumulation of nitrate-n in the deep tillage turning field was larger， which was 8.15 and 9.57 mg/kg higher than that of shallow-turning and no-tillage. but in the mature period， it was the largest in the no-tillage treatment， which was 19.23% and 14.68% higher than that of t

11、he shallow tillage turning field and the deep tillage turning field.the soc content with deep tillage turning field in 30-40 cm soil layer was higher 3.33 and 3.86 g/kg separately than no-tillage and shallow tillage turning field.conclusionin the same tillage method， the soil nitrate n content in the short-term continuous straw returning treatment was lower than that without straw returning， and the straw returning depth affected the soc content in different depth soil layers.key words  meadow;straw return;soil organic carbon;nitrate-n;distribution characteristic