Applicability Study On Polyacrylamide(PAM) Application In Slope Red Soil Of Tea Garden

In recent years, along with the tea prices continue to rise, tea production bring good economic benefits, so the tea famers continue to increase the reclamation efforts of tea garden, parts even assart in more than25°slope. Additionally, tea garden rarely take soil conservation measures because of the tea production management mode, so the soil erosion is very serious. Therefore, there is important practical significance for soil and water conversation and developing eco-friendly agriculture to look for high efficiency soil conservation measures for red soil tea garden (especially for newly reclaimed tea garden). In this thesis, the tea garden red soil of Anxi County Fujian Province was selected as the research object, aim to chose suitable polyacrylamide (PAM for abbreviation) and its best mode of application by artificial simulation test. The study analysed the effects of five different PAM application concentration (which were1/10000,3/10000,5/10000,7/10000,10/10000, showed by PAM1, PAM3, PAM5, PAM7, PAM10, especially) on nutrient leaching losses and soil erosion, and the vertical migration and residues condition of PAM, then sifted suitable PAM and its best mode of administration and application concentration. The main conclusions are as follows:(1) From the effect of reducing the amount of runoff and sediment of red soil tea garden, three PAM of a molecular weight of15million with different degree of hydrolysis of10%,20%,30%were compared, and the PAM of10%degree of hydrolysis is the most suitable for application in the tea garden of red soil; and aqueous solution applied is the best way of application.(2) PAM effectively reduced nitrogen and phosphorus leaching losses in tea garden, and there were significant differences effects in different PAM application rate. Compared with the control, after PAM application, the leaching losses of ammonium nitrogen, nitrate nitrogen and phosphorus reduced6.96-73.69%、37.55%-74.71%and44.90-90.48%respectively; The effect of PAM7was the best way to reduce nitrogen leaching loss, and PAM10was followed; the effect of PAM10was the best way to reduce phosphorus leaching loss, and PAM7was followed; but PAM application promoted potassium leaching losses, and the effect of PAM7was not very clear.(3) PAM residues were mainly concentrated in the0-20cm tilth, only a small part along with the vertical distribution of soil moisture permeated into the soil below20cm, but the residues of different application amount of PAM did not exceed500mg/kg standard; PAM residues in the soil decreased with increasing of soil depth; from all processing, the residual rate of PAM7was the lowest.(4) PAM could effectively improve the corrosion resistance of the tea garden of red soil, and reduce the runoff and sediment losses of tea garden topsoil; when the application rate of PAM was2.80g/m2, the effect of reducing soil erosion was the most significant.