Effect Of Fertilization On Primary Productivity And Soil Nutrients Of Alpine Meadow In Three River Source Region

The Headwaters of Three Rivers known as China′s―water-tower‖, which refersto the source region of Yangtze River, Yellow River and Lancang River. The soil hashigh water holding capacity with its rich-organic-matter and a good vegetation cover.factors that favor water retention. The area of the Headwaters of Three Rivers isabout318,000km2, which is half of the Qinghai Province and plays an irreplaceablerole in stabilization of Qinghai’s (and national) animal husbandry industry. Because alot depends on the health and sustainable management of the soil and vegetationresources it is subject of study. The differentiation of aboveground phytomass andsoil nutrients of alpine meadow was investigated, and the responses of primaryproductivity, plant nutrients and soil nutrients to fertilization were studied on themonitoring station of Qinghai University. The main results were as follows:1) The aboveground phytomass and soil nutrient contents of alpine meadowwere measured for analyzing the differentiation and relationships between soilnutrients and aboveground phytomass at6sites with different altitudes (4056m,4221m,4263m,4293m,4332m,4427m). The results indicated that soil organicmatter content, total nitrogen, available nitrogen, available phosphorus and availablepotassium were higher at both low and high altitude sites, but lower at the middlealtitude sites. Total phosphorus content showed a stable pattern with the increase ofaltitude. The aboveground phytomass showed a similar variation with the totalnitrogen, total potassium, available nitrogen and available potassium contents. Andthere were significant positive correlation between phytomass,total nitrogen, andavailable potassium.2) The quadratic orthogonal regression design was used to determine the effectsof N, P and K fertilizers in the alpine meadow in Yushu Prefecture of QinghaiProvince. The results showed that the N and P in the alpine meadow weredeficienct, but the K was sufficienct, the order of effect of3fertilizers on forage yieldwas N>P>K. The fertilization increased the contents of N, P and K in plant instead of soil. The optimum fertilization combination for increasing forage yield was269.6kgN/ha+119.3P kg/ha.3) The effects of different fertilizer application time and amount on phytomass,plant nutrients and soil nutrients were different. The results showed that increment infresh weight and dry weight when fertilizer dose rate was150kg/ha and fertilizertime was applied on10thJuly, were1.64times and2.06times higher respectivelythan CK. Compared with CK, the mass fractions of plant nitrogen was31.2%higherwhen fertilizer dose rate was300kg/ha and fertilizer time was25thJuly. Correlationanalysis showed that plant total nitrogen was significantly positive correlated withfresh weight and dry weight. There were significant correlation between nitrogenfertilizer and plant total nitrogen. Above findings suggested that primary productivityand soil total nitrogen values were greatest when fertilizer dose rate was from150kg/ha to300kg/ha and fertilizer time was10thJuly.4) The effects of different types of nitrogen and dose rate to phytomass, plantnutrients and soil nutrientsvaried.. The results showed that the order of effect of3fertilizers on phytomass and plant nutrients was sulfate fertilizer>calcium nitratefertilizer>urea fertilizer. The fresh weight, dry weight, plant total nitrogen and soiltotal nitrogen of ammonium sulfate treatment were the largest number when dose ratewas200kg/ha. And all ammonium nitrogen was significantly higher where nitratefertilizer and urea fertilizer were used than when using sulfate fertilizer. Thecorrelation analysis showed that plant total nitrogen, soil ammonium nitrogen andaboveground phytomass were significantly positively correlated with ammoniumsulfate fertilizer (P<0.05). There was a significantly positive correlation (P＜0.01)between soil nitrate nitrogen and calcium nitrate fertilizer. The experiment ofdifferent dose rates of ammonium and nitrate nitrogen fertilizer results showed thevalues of fresh weight, dry weight and belowground phytomass when ammonium andnitrate nitrogen fertilizer ratio was100:0.5) Vegetation coverage, plant height and aboveground phytomass weresignificantly better than CK when yak manure was applied as fertilizer. But Pielou indexes and Shannon-Wiener indexes of different sites were significantly lower (P＜0.05) than CK when yak manure was applied at a rate of1100kg/ha. These findingssuggested yak manure fertilization had significant impact on plant communitystructure and productivity. Both soil fertility and productive capacity of alpinemeadow were improved, by spreading yak dung and the benefits also includereductions in environmental pollution that can occur in run off from areas on whichchemical fertilizer are applied. It is worth trying to popularize yak manurefertilization, provided that the people can get alternative fuel supply to cook theirfood.