| China is a country with high productivity of straw. Statistical results in2006showed thatstraw productivity overtakes7.6×108t in China. As one of the major grain producing areas, Jilinprovince has2.4×107t corn straw in2010and values about15×108￥. However, such greatamounts of resource has not been properly used, nearly30%of straw was burnt after harvest inNortheast areas in China. Burning straw will causes problems like air pollutions, traffic safety,fire hazards and other social problems. On the other hand, Northeast areas in China are nowfacing a serious problem of soil degradation. Soil thickness, fertility, physical and chemicalproperties deteriorate gradually since reclaimed.Some of farmlandhas lost the agriculturalproductive capacity. Thus, aiming at problems of waste of straw and soil degradation, this papercontrasted the vertical distribution of soil organic matter (SOC), humic acid (HA), fulvic acid(FA) and structural characteristics of HA under straw deep application (SDA) and differentfertilizations. To provide a theoretical basis for develop the fertility of subsurface soil andproperty utilization of straw resource, and to provide basis data for further research forsubsurface fertilization, this paper researched the influence of SDA on soil organic matters. Theconclusion as below:(1) SDA with2years and SDA+1/3O+NPK can improve the content of SOC, and moresignificantly at20~40cm. The content of SOC decreased with the increasing of depth, and ahigh rate reduced at about20cm. The content of SOC of SDA+NPK and SDA+1/3O is higher inthe spring than in autumn at20~40cm.(2) The content of HA of SDA with2years and SDA+NPK increased at0~40cm, andsignificantly increased at20~40cm. The content of HA of SDA+NPK and SDA+1/3O+NPKdecreased with the increasing of depth. The content of HA of SDA+1/3O and SDA+1/3O+NPKin the spring are higher than in the autumn.(3) The content of FA improved with the treatment of SDA. Among all the treatments, thecontents of FA decreased significantly at20~30cm, and at a low level at20~40cm. The contentof FA of SDA with2years and SDA+1/3O+NPK is higher in the spring than in the autumn.(4) The PQ value reduced after SDA, and so as the humification level. The PQ values ofSDA with2years are lower in the spring than in the autumn, while the others changed little.(5) SDA+NPK complicated the structural characteristics of HA. After2years of SDA, thestructural characteristics of HA are more complicated with the increasing of depth, and thecondensation increased but the oxidation decreasd. The structural characteristics of HA are more simple in the autumn than in the spring. |
