EFFECTS OF PHOSPHORUS APPLICATION METHODS ON NUTRITION UPTAKE AND SOIL PROPERTIES OVER 12-YEAR FIELD MICRO-PLOT TRIALS: II. SOIL-AVAILABLE MICRONU- TRIENTS AND THEIR RELATIONSHIP WITH SOIL PROPERITIES

摘要

In a long-term P micro-plot experiment with meadow brown soil conducted since 1997 in Shenyang, China, changes in soil-available micronutrients (Zn, Fe, Cu and Mn) were investigated and statistically related to soil properties of Olsen-P, total P, SOC, total N and pH. Four fertilization methods were included in the micro-plot experiment: unfertilized control, N fertilization annually, N and P fertilization annually, N fertilization annually and P fertilization once every 6 years. Compared to the unfertilized treatment, each of the fertilization methods increased the concentrations of available Mn, Fe and Cu but not Zn, throughout the trial period. Both P application rates and methods influenced soil-available Zn and Fe but not Cu and Mn. It was concluded that P application once every year and once every six years contributed to the availability of soil Zn and Fe, respectively. When taken as a canonical variable, the soil properties could well forecast the available Mn but poorly predict the other micro-nutrients. Path analysis showed that soil pH, total P and SOC were the three main factors directly influencing the soil-available micronutrients, while Olsen-P played an indirect role via them.