保护性耕作对坡耕地土壤微生物量碳、氮的影响

利用长期定位试验(1999年开始保护性耕作,2004年采样测定),研究了豫西旱区坡耕地不同保护耕作对土壤有机碳、全氮和微生物量碳(SMB-C)、微生物量氮(SMB-N)的影响.结果表明:深松覆盖和免耕覆盖耕层有机碳、全氮较传统耕作均有增加,其中深松覆盖耕作下有机碳含量最高,为6.79 g/kg,比传统耕作增加了13.82%;免耕土壤全氮含量最高为0.797 g/kg,比传统耕作增加了10.42%;土壤有机碳、全氮随着土层的加深逐渐降低;长期保护性耕作(免耕、深松)显著增加了土壤微生物碳、氮含量,0～20 cm免耕和深松的土壤SMB-C、SMB-N含量分别较传统耕作增加79.3%,19.9%和17.92%,8.13%.长期耕作导致坡耕地土壤微生物碳、氮具有不同程度的坡下富集现象.土壤SMB-C与全氮、SMB-N呈显著正相关.由于微生物量C、N可作为评价土壤质量的生物学指标,因此可以认为,长期保护性耕作(免耕和深松)可以提高豫西旱区坡耕地土壤质量,增加土壤肥力.

Change of SMBC and SMBN under Conservation Tillage on Sloping Dryland

In order to study the change of the SOC's,Nitrogen's,SMBC's and SMBN's contents in soil,a experiment on the long-term locating field plots was performed smoothly on the semi-humid areas of the west of the Henan province.The results suggested that organic carbon in soil and nitrogen in soil are both increased under the sub-soiling tillage and no-tillage.Comparing with the other tillage patterns,the sub-soiling tillage have a highest SOC contents in soil,that is 6.79 g/kg,13.82% improved comparing to the traditional tillage.Nitrogen contents in soil under no-tillage have a highest contents among the above tillage patterns that is 0.797 g/kg,10.42% improved comparing to the traditional tillage.SOC and nitrogen is decreasing with soil layer being deepened.In the 0~20 cm soil layer under the sub-soiling tillage and no-tillage,SMBC and SMBN contents have been 79.3%,19.9% and 17.92%,8.13% improved comparing to the traditional tillage,and then the phenomenon of the bacterial enrichment was occurred under the low sloping soil.The positive co-relation distinguishedly was appeared between the SMBC and nitrogen in soil,SMBN,SMBC,and SMBN can be considered as the biological indexes to estimate the quality of the soil,for which have a distinguished relation.Hence,the subsoiling tillage and no-tillage have perfect future in appliance.