Effect Of Fertilizer On Contents Of Nitrogen And Phosphorus In Soil Infiltrative Water And Soil Nutrient In Phyllostachys Praecox Stands

Phyllostachys praecox belongs to Phyllostachys of Bambusoideae (Gramineae),it is an important bamboo species mainly for producing edible bamboo shoots. An intensive cultivation technique has been adopted by majority of farmers since 1980s. The technique has already been conducted to improve economic benefits, but caused serious environment problems, such as soil acidification, over-accumulation of N, P and K, especially P, exceeded standard of nitrate concentration in bamboo shoots, and pollution of water systems in the production areas. By field investigation, this thesis made a research on soil phosphorus status and loss potential of Phyllostachys praecox stands under intensive management, calculated the threshold value for the phosphorus leaching, and made a study on relationships between different fertilizer and nitrogen and phosphorus leaching load,ratios of soil nutrient surplus,fertility use efficiency , and bamboo shoot yields,use a soil infiltrative water collecting equipment and position experiments, the main results were as follows:(1)To reveal the soil phosphorus status and its leaching risk for Phyllostachys praecox stands under intensive management, 10 soils of typical sites which locate across 5 villages in Lin'an were sampled, and the soil phosphorus loss threshold value and potential for Phyllostachys praecox stands were determined through chemical analysis measures and Langmuir isotherm equation. The results showed that average content of available phosphorus for the 10 soil samples was 169.25 mg·kg^-1. The correlations were significant that simulated by Langmuir equation (R² = 0.987-0.999). The Equilibrium Phosphorus Concentration at Zero Sorption (EPC₀) of 6 sites were more than 0.02 mg·L^-1;The Degree of Phosphorus Sorption Saturation (DPS) of 10 sites had an average of percentage of 46.18% with 82.94% as the highest, and the values for 7 sites were significantly higher than 25%. There was a significant linear correlation between the CaCl₂-P and Bray-P. The content of Bray-P was 52.52 mg·kg^-1, which was the threshold value for the phosphorus leaching from soils. 9 sites were higher than the threshold value, and the highest value was 5.45 times of the value. The range of standards required of the phosphate for Phyllostachys praecox stands calculated by Langmuir equation was 8.14-64.66 kg P·hm^-2, the average amount was 27.41 kg P·hm^-2.(2)To make clear the effect on nitrogen and phosphorus leaching under characteristics of nitrogen and phosphorus infiltrative leaching from phyllostachys praecox stands of different fertilizations under natural rainfall were studied with a soil infiltrative water collecting equipment. Set five different fertilization treatments, controlling with no fertilizer, conventional fertilizer, special compound fertilizer, slow-release fertilizer and microbial fertilizer. The results showed a significant linear correlation between the amount of infiltrative water and rain precipitation. The concentrations of TN and tall TP were increased with increasing of fertilization rate. The average concentrations of TN and TP were in the range of 24.53-79.19 mg·L^-1 and 1.81-3.88 mg·L^-1, respectively. DON was the predominant form of DN in infiltrative water, which averagely account for 75.13%; The leaching loss of phosphorus was mainly in the form of DP, which had a average percentage of 64.69%-72.10% among the five different fertilizations. The accumulative load of nitrogen and phosphorus were 64.76^-180.03 kg·hm^-2 and 4.63-8.78 kg·hm^-2 in the whole trial process, respectively. Under the conventional fertilizer, the leaching load of nitrogen and phosphorus were highest, accounting for 36.73% and 11.11% of nitrogen application rate and phosphorus application rate, respectively. As compared with the conventional fertilizer, the special compound fertilizer treatment were decreased by 31.6%å'Œ41.0%, respectively, so the results showed that application of the special compound fertilizer can reduce the risk of agricultural non-point source pollution.(3)A field experiment was conducted on a Phyllostachys praecox stand of Lin'an county, Zhejiang province, China in 2009 to compare the effects of conventional fertilization (CF), controlled-release fertilizer (CRF), special compound fertilizer (SCF),and microbial fertilizer (MF) on soil fertility quality, fertility use efficiency, and bamboo shoot yields of Phyllostachys praecox stand. The results showed the degrees of excessive-accumulation of available N, P, and K in the soil and soil acidification induced by fertilization followed the order of : CF>SF≈CRF>MF. The lowest fertilizer agronomic efficiency was obtained from CF and its agronomic efficiencies of N, P, and K were 4.7 , 23.6, and 14.2 kg fresh shoot·kg^-1. As Compared to the CF, application of SCF and CRF increased agronomic efficiencies of N, P, and K by 40.4-53.2%, 50.8-90.7%, and 35.5-39.5%, respectively, whereas application of MF increased agronomic efficiencies of N, P, and K by 38.9,0.68 and 2.0 times, respectively. Compared to the control, CF increased bamboo shoot yields and economic benefit by 29.6% and 14.3%, respectively,where application of SCF,CRF, and WF increased bamboo shoot yields and economic benefit by 27.5-29.0% and 14.6-17.8%, respectively.