玉米间作大豆、萝卜对红壤不同粒径水稳性团聚体碳氮分布的影响

为了探讨不同种植模式对红壤水稳性团聚体粒径分布以及不同粒级团聚体中有机碳、氮含量,土壤微生物量碳、氮含量的影响,选择大豆、萝卜与玉米间作及3种作物的单作进行田间试验,在作物成熟期采样,进行样品测定。结果表明:在玉米-大豆(玉//豆)、玉米-萝卜(玉//萝)、玉米单作(玉单)、大豆单作(豆单)、萝卜单作(萝单)处理中,大团聚体(> 0.25 mm)的百分含量明显高于微团聚体(<0.25 mm),其中以大团聚体中粒径为0.25~2 mm的百分含量最高且显著高于其余两种粒径,大团聚体百分含量表现为:玉//豆>玉//萝>玉单>萝单>豆单,微团聚体则与其相反。团聚体粒径中的有机碳含量表现为0.25~2 mm粒径最高、<0.25 mm粒径次之、>2 mm粒径含量最少、玉米大豆间作含量最高、玉米单作含量最低。团聚体粒级中全氮含量与有机碳分布一致,但单作的全氮含量高于间作。有机碳与全氮的C/N为间作高于单作,>2 mm粒径C/N高于其余两种粒径。微生物量碳、氮在团聚体粒径中的分布趋势一致,都表现为间作模式高于单作模式,大团聚体中的含量高于微团聚体。微生物量碳、氮的C/N为单作模式高于间作模式,微团聚体大于大团聚体。与单作相比,间作能提高土壤中水稳性大团聚体的含量,增加大团聚体粒径内的有机碳、氮及微生物量碳、氮的含量。

Effects of maize//soybean and maize//radish inter-cropping on the carbon and nitrogen distribution of water-stable aggregates in red soil

To investigate the effects of different planting patterns on the grain size distribution of water-stable aggregates,the contents of organic carbon and nitrogen in aggregates with different grain sizes,and the contents of soil microbial biomass carbon and nitrogen in red soil,field experiments were carried out on inter-cropping maize(Zea mays L.) with soybean [Glycine max(L.)Merr.]and radish(Raphanus sativus L.)respectively,as well as sole-cropping systems of these three crops.Crops were sampled at their mature stage.The results showed that: in the treatments of inter-cropping systems of maize//soybean and maize//radish,and sole-cropping systems of maize,soybean and radish,the percentage of macro aggregates(> 0.25 mm)was significantly higher than that of micro aggregates(<0.25 mm),and the percentage of macro aggregates with grain size of 0.25 ~ 2 mm was significantly higher than that of the other two kinds.The percentage of macro aggregates was shown as: maize//soybean>maize//radish>sole-cropping maize>sole-cropping radish>sole-cropping soybean,while the percentage of micro aggregates performed the opposite.As for the amount of organic carbon,aggregates with 0.25 ~ 2 mm grain size occupied the most,followed by those with grain size less than 0.25 mm,and those with grain size bigger than 2 mm contained the least.Maize and soybean inter-cropping contained the most organic carbon while sole-cropping maize contained the least.The distribution of total nitrogen content was as same as organic carbon in aggregate fraction,but the total nitrogen content of sole-cropping was higher than that of inter-cropping.C/N ratio for organic carbon to total nitrogen of inter-cropping was higher than that of sole-cropping,and C/N of grain size >2 mm was higher than that of the other two kinds. The distribution trend of microbial biomass carbon and nitrogen in aggregate grain size was consistent,both showed that the content of inter-cropping pattern was higher than that of sole-cropping pattern,and the content of macro aggregates was higher than that of micro aggregates.As for the C/N of microbial biomass of carbon to nitrogen,the sole-cropping pattern was higher than that of the inter-cropping pattern,and micro aggregates were higher than macro aggregates.Compared with solecropping,inter-cropping could improve the content of water-stable macro aggregates in soil,increase the content of organic carbon and nitrogen,and the content of microbial biomass of carbon and nitrogen in the grain size of macro aggregates.