Researches Of Water, Soil And Nutrients Loss From Bamboo Forest

On the distributing map of China bamboo, Changjiang River to the South inChina which locates between north latitude 25°-30°is the region where is the largestbamboo area and the richest bamboo resources. And bamboo area of ZhejiangProvince achieves 11,76 thousand mu, which occupies 16.18% of the wholecountry'S.In the DaiXi watershed in Hu Zhou, the main industrial forest is bamboo forest,of which planting area occupy about 1/5 of agriculture and forest land use. Such largearea will cause terrible water eutrophication right around when meet storm rainfull.Further more, a water-storage reseroir of which total reservoir capacity is 99.66million m³ will be set up in the DaiXi watershed. Therefor, studying the loss circs ofrunoff, silt and nutrient under different soil nutrient content and various rainfull inbamboo forest is very important for constituting water source land of water-storagereservoir protection layout, and the water-storage reservoir's continuabledevelopment.By the method of field artificial precipitation and lab analysis, this article havestudyed runoff producing, silt producing' procedure character, the loss of nitrogen,phosphorus and other nurishment's dynamic procedure character, and the lossquantity, of runoff, silt and nurishment, under different soil nutrient content andvarious rainfull. Discovered that: (1) The pollution of nitrogen and phosphorus in thewater-reservoir in Daixi watershed is terrible, especially the content of totalphosphorus belong to theâ…¤class water. (2) Content of nurishment in the runoff ismore than in the soil of surface ground. (3) After runoff having started 15 minutes,the content's changing trend of runoff silt is from high to low, which range 0.04%to1.18% at first, and then achieve balance point; stronger raininess, larger balancepoint's absolute value; but application fertilizer have little influence to balance point.When raininess is 1.0mm/min, the content of runoff silt under three applicationfertilizer tends to 0.2% at last, and when raininess is 0.6mm/min, it tends to 0.05%;the runoff quantity will increase by time, under moderate and high application fertilizer, runoff for 1 hour, when raininess is 1.0mm/min, the runoff quantity rangefrom 0.05mm to 0.56mm, when raininess is 0.5mm/min～0.6mm/min, the runoffquantity range from 0.03mm to 0.13mm; when raininess is 0.5mm/min, 0.6mm/minand 1.0mm/min, under the three application fertilizer, the soil erosion modules do notsurpass 0.07t/ha, and the lowest value is 0.00025t/ha; under moderate and highapplication fertilizer, when soil moisture content before precipitation is high, the soilerosion module is more than when soil moisture content is low. (4)The loss quantityof NH₄-N, total phosphorus in runoff, avallabe phosphorus carried by runoff silt,organic substance all increased by time; higher soil available phosphorus content,less influence that raininess to available phosphorus loss. (5) The NH₄⁺-Nconcentration in rainfall reduced during the rain duration, and reached to a stablelevel at last, but the time cost to reach the stable level were variated among differentnitrogen content soils; raininess has little influence to the balance point. (6) In thesame raininess, NH₄⁺-N loss quantity has marked correlation with soil availablenitrogen content, and R²=0.9554. (7) Soil total phosphorus, soil available phosphorusis seperately related with the total phosphorus concentration in runoff markedly, andR² seperately achieved 0.9982 and 0.9435. (8) Organic substance lost mainly cardedby silt, and its loss quantity is nearly related with silt loss quantity.At the same time, according to artificial precipitation data and SCS methodinvented by the U.S. Water and Soil Conservation Bureau, I have established a runoffprediction model for bamboo forest in Tiger Pool watershed.