Effect Of Deep Incorporation Of Corn Stover Combine Chemical Fertilizer On Physicochemical Properties And Humus Of Soil

Every year China produces huge volumes of crop straw, most of which, however, is burnt by the farmers in the fields. Burning of straw in open fields will not only reduce the contents of soil organic matter and soil moisture in the surface soil layer, but also bring about environment pollution and damage human health.The crop straw contains rich in nitrogen, phosphorus, potassium and trace elements.“Corn stover deep incorporation”(CSDI) not only is believed to be able to effectively solve the problem of how to utilize crop residue as resource and a number of other problems caused by burning of crop straw and further on help sequestrate carbon, raise water holding capacity, improve soil fertility and stabilize crop yield; but also can effectively break the the plow pan, solve the problem of soil plow layer becomeing gradually shallow.A field experiment was conducted in a mono-cropping corn field at the Experiment Station of the Jilin Agricultural University,with four treatments,is,CK(no-corn stover incorporated), CS(CSDI), NPK(fertilizers applied only) CS+NPK(CSDI plus fertilizers application) designed to explore effects of corn stover deeply incorporated in addition to fertilizers application on composition of soil humus and structure of humic acid(HA)in the soil. Humus was divided into humic acid(HA), fulvic acid(FA) and humin(HM).Soil samples were collected from the four treatments for analysis of humus composition with the modified humus component extraction method and for structure of HA with the IHSS method for purification and the infrared spectroscopy for element composition. The results show that:(1) The treatments CS and CS+NPK promote soil compaction and soil bulk density reduced, no significant effect on soil pH and conductivity; CS increased slightly soil available nutrient content, NPK and straw CS+NPK promote soil available nutrient content increased significantly.(2) CS+NPK was better than CS and more better than NPK on the accumulation of SOC.Generally, soil organic carbon(SOC) content of the surface(0 ~ 20cm) was higher than the subsurface(20 ~ 40cm). the straw layer(50 ~ 55cm)of the treatments CS and CS+NPK in SOC content and the rate of increasing reached the highest, and were conducive to accumulation of SOC in all soil layers.(3) The treatments CS and CS+NPK also prompted a significant increase in component of humus, The treatment CS maximum value of organic carbon content of FA exists in 20 ~ 40 cm, and of HA and HM exists in 50 ~ 55 cm place. The CS + NPK treatment maximum value of organic carbon content of HA, FA and HM maximum carbon content exists in 50 ~ 55 cm. PQ value showed first rise after falling trend with increasing depth, but did not affect significantly.CS also reduces the ΔlgK value soil of HA and FA surface and subsurface, prompting its molecular structure becomes complicated, CS processing and CS + NPK treatment on straw upper soil HA of ΔlgK was no significant impact, FAΔlgK value on the performance of the upper more significant, the lower layer is not significant.(4) The treatments CS and CS+NPK increased the proportion of aromatic-C in HA, and Treatment CS also increased the proportion of aliphatic chain hydrocarbon in HA, while treatment CS+NPK raised the condensation degree and lowered the oxidation degree of HA, which means the two treatments differed in mechanism of making HA stable. Besides their effects of improving the aromaticity of HA in molecular structure, Treatment CS also enhanced hydrophobicity of HA, and Treatment CS+NPK made the structure of HA more complicated.