Effects Of Soil Cornstalk Fertilization On Nutrient Leaching In Soil Macrospore Flow

Nowadays, the environmental pollution increased following the increaseing employ of fertilizer. A great deal of fertilizer inpour the water along with rain or irrigation, and result in eutrophication and groundwater pollution.In the leaching of fertilizer, the water and solute are not underflow uniformity. Because of the different hole'size, the underflow rate is not homology. The macropore flow move quickly, and the water flux is bigness. Research show that through the percent of soil macropore is small (about 0.32 percent), it can conduct more than 90 percent water flux. It is important to consider the effects of soil macropore. The soil macropore and macropore flow not only affect the mobilization of water and solute, but also impress the validity of precipitation and irrigation, and polluted the groundwater. So it is very important to take research on soil macropore and macropore flow, and has its theory and reality meaning to save water and reduced leaching of water and solute.By the field experiment and indoor simulation, the effects were investigated of the soil cornstalk fertilization on nutrient leaching in soil macorpore flow and the mechanism. The main conclusions showed as followed:The research was taken up on the influence of cornstalk fertilizer to soil macorpore and the nutrients leaching in macropore flow. And to offer some theory according as for manpower improve soil and control the nutrient's leaching in micropore flow. It include three aspect of the research content: firstly, the effects of organic fertilize soil to the nutrient leaching in macropore flow. By the method of field experiment and indoor's simulation, to investigate the changes of nutrient's leaching in soil micropore flow and the distribution of nutrients in soil section; secondly, the effect of organic fertilize soil to soil macropore. By the taken of original soil core, combine with the digital analyze, to investigate the changes of the shape, number, perimeter of macropore; thirdly, the influence mechanism of organic fertilize to macropore and macropore flow. By the analysis of the changes of soil physic and chemical properties, to investigate the the influence mechanism of organic fertilize to macropore and macropore flow. The results show:(1) Soil fertilize by corn stalk can reduce the nutrient leaching in macropore flow, and decrease the leaching of nutrient, but the effect is different to different nutrient. It is more effective to positive ion and the total leaching of NH+4-N without cornstalk is 4.54 times more than corn stalk applying, and has little impact to NO3—N. The result showed that soil fertilize with corn stalk is effective in reduce nutrient leaching and decrease groundwater pollution.(2) Corn stalk fertilize soil can slower the macropore flow and cut down the gross of nutrient leaching. The leaching gross of corn stalk fertilize is 50 percent of the gross without corn stalk apply. It is useful in reduce the groundwater pollution.(3) Corn stalk fertilizer can keep more nutrient, but in the anaphase the polluted possibility increased if the rain or irrigation is enough.(4) The changes of different nutrients along the level heading of soil macropore show: the nutrients in soil macropore wall are the highest, and then reduced along macropore wall, the content of nutrient become steady and same with the content of soil matrix. The result approved the existence of macropore flow with high solute concentration in soil macropore.(5) The shapes of Black soil mostly are pores , and the fissure is few, and the fissure is fewer after organic fertilize. The mainly reason is the high content of organic and nicer structure.(6) Corn stalk apply reduce the soil macroporosity, but the soil porosity increased and mainly increased the capillary porosity. The macroporosity reduced 30 percent and the total porosity increased 3.68 percent, the capillary porosity increased 8 percent. The result means that corn stalk fertilize mainly increased the pores which conduct water.(7) With the applying of corn stalks, the macropore's perimeter in level direction and vertical direction were reduced. It means the decrease of macropore with bigger diameter.(8) The perimeter of macropore increased in transverse section but the number decreased, it shows with the deeper the soil profile, not only the number macropore decreased but also mainly decreased the macropore of big diameter.(9) The reason of the lessen of nutrient leaching is: the cation exchange capacity increased and can keep more nutrient; also the water holding function increased and macroporosity decreased, so the gross of underflow was reduced.(10) The quantity of accumulation increased with the applying of corn stalk, and the soil's structure and pore were improved. The capillary pore increased so enhance the soil faculty of holding and harmony water, so reduce the amount of leaching nutrient in soil. (11) The breakthrough curve is different with the different macropore flow, and the curve was delayed more obviously when applied the organic matter. It showed the macropore decreased with the applied of organic matter, so the quantity of nutrient decreased too.As a whole, the application of cornstalks have obvious effects on the increase of soil nutrient holding ability, reduce the nutrient leaching, improve the soil structure and porosity, increased the water keeping ability and cut down the number of macropore. The results are important in soil improve and nutrient leaching decreased, also are practical and meaningful.