| Carya cathayensis Sarg. forest has become one of the most important cash forests in China. Itplays an important role in the local economy and become the major income source for many farmers.According to survey, plantation area of Carya cathayensis Sarg. stands was over8.3×104hm2, Morethan400,000people directly benefit from the relevant industry. However, improper management inCarya cathayensis Sarg production has resulted in many ecological and environmental problems, suchas loss of biodiversity, soil erosion, and deteriorated water quality. Four field surveies and experimentswere conducted to （1） investigate nutrient status of the soils under Carya cathayensis Sarg. stands;（2）investigate dynamic dhanges of the nutrients in percolating water from the soil under Carya cathayensisSarg stands;（3） compare characteristics of nitrogen (N and phosphorus （P）losses in the runoff wateron the soils under Carya cathayensis Sarg stands with different fertilizations,（4） determine reductioneffect of buffer zones on N and P losses in the seepage water from the soils under Carya cathayensisSarg stands. The main results of this stuy were as follows:（1） Ananlytical results of298soil samples collecting from10villages and towns of Lin’an county,Zhejiang province from July to August,2011showed that average value of soil pH was4.89, whichsuggesting that the soils under Carya cathayensis Sarg. stands tended to acidification in optimumplanting zones. Compared to suitable planting zones, the optimum planting zones had lower soil pH andhigher contents of organic matter and available nutrients.The content of organic matter as well as thecontents available N, P, and K in the optimum planting zones were194.9,6.7, and33.8g·kg-1,respectively, whereas variation coefficients of organic matter as wel as available N, P, and K in thethose zones were46.5,34.8,115.5, and51.9%, respectively, suggesting that organic matter and nitrogenin the soils under Carya cathayensis Sarg stands in the optimum planting zones were over-accumulation. The contents of organic matter as well as the contents available N, P, and K in thesuitable planting zones were29.5,180.1,2.6, and91.1mg·kg-1, respectively, whereas variationcoefficients of organic matter as wel as available N, P, and K in the those zones were35.0,26.2,145.4and47.9%,respectively.（2） The law of nutrients leaching loss in the soils under different Carya cathayensis Sarg standswith conventional fertilization was studied. The results showed that dissolved nitrogen （DN） was the predominant form of N leaching loss inform the percolating water. Average content of NO3--N was up to9.39mg·L-1, which accounting for76.5%of DN. The peak value of NO-3-N in percolating waterreached17.84mg·L-1. Average contents of total P and dissolved phosphorus （DP） were0.65mg·L-1and0.45mg·L-1, respectively, which exceed the critical concentration of eutrophication pollution.Fertilization affects nutrient concentrations in the leakage water from the soil. The peak values of totalN （TN）, total P （TP）, DN, DP, and NO—3N concentrations came after fertilization（3） Effects of different fertilizer treatments on N and P runoff losses under the field condition werestudied through setting runoff plots uner Carya cathayensis Sarg stands. The results showed that the TNand TP runoff losses decreased with time of fertilization. DN or DP was the main forms of N or P runofflosses. Runoff losses of DN was accounted for79.43-83.60%of TN, whereas runoff losses of DPN wasaccounted for47.65-75.39%of TP. Special fertilizer for Carya cathayensis Sarg had a good ability tocontrol runoff losses of N and P. Compared to the treatment of conventional fertilization, broadcast andfurrow application of special fertilizer reduced runoff losses of N and P by35.73%,32.37%and43.37%,38.46%, respectively, which effectively reduced runoff losses risks of N and P.（4） A field experiment was conducted to determine the characteristics of nutrient leaching lossesfor four different hedgerows （Phyllostachys praecox, Photinia fraseri, ryegrass, healthland）, in Caryacathayensis orchard. The results indicated that the reduced effect of different hedgerows on nutrientleaching losses was highest under Phyllostacys praecox stand，followed by Photinia fraseri, ryegrass，and the lowest under healthland. The intercept loads of TN by Phyllostacys praecox stand，Photiniafraseri, ryegrass，and healthland were7.52,7.21,6.95, and4.10kg·hm-2, whereas the intercept loads ofTP for these4hedgerows were0.34,0.14,0.29, and-0.03kg·hm-2.DN or DP was the main forms of Nor P leaching losses. |
PDF Full Text Request