冬小麦套种草木樨土壤中根瘤菌分布与土壤理化性质的相关性分析

Correlation between rhizobia distribution and the physical/chemical properties in soil of winter wheat intercropped with sweet clover

对新疆阿克苏地区冬小麦套种草木樨地土壤中根瘤菌数量动态规律与土壤理化性质的相关性进行了研究。采用平板稀释法对根瘤菌进行计数,测定土壤理化性质包括水分、pH、容重、有机质、全氮、碱解氮、速效磷和速效钾。结果表明:1)从冬小麦返青也是草木樨播种时期(4月)到刈割期(9月),根瘤菌数量分布为10~20cm>0~10cm>20~40cm土层,0~20cm土层根瘤菌数量7月达到最大值,为6.89lg cfu·g^(-1),20~40cm土层根瘤菌数量8月达到最大值,为6.46lg cfu·g^(-1);非共生期根瘤菌比共生期增加7.33%~10.63%。2)4-9月土壤pH下降0.23%~1.40%,全盐下降3.45%~37.69%;0~40cm土层4-8月有机质、全氮、碱解氮、有效磷呈下降趋势,但在9月草木樨刈割时较8月有所增加,其中0~40cm土层的有机质增加7.65%~26.98%,全氮增加16.67%~44.12%;0~20cm土层碱解氮增加20.27%~160.68%;10~20cm土层有效磷增加167.74%;0~20cm土层的有效钾含量提高10%。3)根瘤菌数量与土壤理化性质的线性回归分析,0~40cm土层全盐与根瘤菌数量相关性最高(R=-0.81,P<0.05)。此外,0~20cm土层水分还与根瘤菌数量相关性高(-0.81≤R≤-0.73,P<0.05),20~40cm土层全氮的相关性高(R=-0.88,P<0.05);通径分析中,土壤全氮、全盐、有机质与根瘤菌数量相关性最高,其中与有机质呈正相关(P5=0.56),与全氮、全盐呈负相关(P_6=-0.50,P_4=-0.64),有机质是促进根瘤菌的主要因子,全氮、全盐是制约主要因子。因此,在栽培过程中应该增加有机肥,适当减少氮肥施量,降低土壤盐分,促进根瘤菌增殖,提高固氮量。

The correlation between rhizobia distribution and the physical/chemical properties in soil of winter wheat intercropped with sweet clover in the Aksu region of Xinjiang was determined.Rhizobia numbers were counted by dilution plate method.Soil physical and chemical properties including pH,soil bulk density,total salt,organic matter,total nitrogen,alkali-hydrolyzale nitrogen,available phosphorus and available potassium were also measured.The results showed that the number of rhizobia was highest at 10-20 cm soil depth compared with 0-10 cm and 20-40 cm from sowing to cutting of sweet clover.The number of rhizobia was highest at 0-20 cm depth(6.89 lg cfu·g-1)in July and at 20-40 cm soil depth in August(6.46 lg cfu·g-1).Soil pH and total salt decreased 0.23%-1.40%and 3.45%-37.69%between September and April,respectively.At 0-40 cm soil depth,organic matter,total nitrogen,available nitrogen and available phosphorus decreased from April to August.However,compared with September(sweet clover harvest)organic matter and total nitrogen in August was increased 7.65%-26.98%and 16.67%-44.12%,respectively.Alkali-hydrolyzable nitrogen at 0-20 cm was increased by 20.27%-160.68%,available phosphorus by 167.74%at 10-20 cm and available potassium by 10%at 0-20 cm soil depth.The correlation between total salt and the number of rhizobia at 0-40 cm soil depth was strong and negative(r=-0.81,P<0.05.The correlations between moisture content and rhizobia numbers at 0-20 cm soil depth were also strong and negative(-0.81≤r≤-0.73,P<0.05).There was also a strong negative correlation between total nitrogen content and rhizobia numbers at 20-40 cm soil depth(r=-0.88,P<0.05).Path coefficients for total salt,organic matter and total nitrogen were generally strongly correlated with rhizobia numbers,and organic matter was positively correlated(P 5=0.56)but total nitrogen and total salt negatively correlated(P 6=-0.50,P 4=-0.64).Organic matter had the greatest positive influence on rhizobia,whereas total nitrogen and total salt reduced rhizobia.