Study On Impact Of Artificial Ecological Forest To The Soil Nutrient Elemen On Loess Plateau

Loess Plateau, located in the juncture of northwest and north part of China, is the world's largest loess area with an area of about 400,000 square kilometers and accounting for 70% of the world distribution of loess. Due to the fine grain size of loess, fluffy soil, the lack of vegetation, concentrated summer and heavy rains, this region is extendedly eroded by water and has become the most serious and typical ecological zone which is featured by water and soil erosion. Therefore, we create an artificial ecology forest, not only with the critical water and soil conservation, but also with the soil of physics, chemistry and biology process strongly interrupted by the artificial forest community, which make the woodland soil fertility and none forest area definitely changed.The construction of ecological forest on the Loess Plateau played a very important role in eco-environment restoration in local regions. The function of artificial ecological forest is becoming more and more obvious in soil and water conservation and the protection of the environment. In this paper, we investigate and calculate the soil N,P,K and SOC in Qianyang,YongShou,Qingling counties in the loess plateau area with variance analysis and regression analysis, especially focus on the soil nutrition element change between artificial ecological forest and before afforestation .Results are listed as follows.1. Experiments were carried out with artificial robinia and orientalis forest in the county of Qianyang on Loess Plateau. The results shows that: in general, the mass fraction of soil organic matter, nitrogen (including total nitrogen and hydrolysable nitrogen), total phosphorus and potassium is highest in the wasteland, intermediate in the robinia forest and lowest in orientalis forest. It shows that robinia and orientalis reduced the mass ratio of soil organic carbon, nitrogen, phosphorus and total potassium, also orientalis'restructuring ability of nutrient elements is better than robinia. Before afforestation ,organic carbon locust woodlands quality of 0～80cm soil overall reduction in the upper layer 4.96%,the most obvious change and growth 30.87% in 0～10cm and the soil is no apparent change. the water to nitrogen oxide reduction, and all the 36.31% and 18.33% , phosphate and potassium the improved 12.28% and 80.77%. k and phosphoric no apparent change;woodlands, are nitrogen oxide, organic carbon the water quality scores were reduced to 30%, and 45.73% 34.57%.The potassium and phosphoric were reduced 5.61% and 4.41%, phosphate and potassium of the 10.71% and 96.04%. overall, the locust and artificial ecology forest to the soil nutrient elements of a strong effect on soil fertility influence. By soil degradation index (DI) shows that robinia increase soil fertility but orientalis reduce soil fertility, furthermore the impact from orientalis is stronger than robinia. Soil organic carbon, total nitrogen, hydrolysable nitrogen, potassium and soil thickness was highly correlated (P<0.05), the mass ratio of available soil organic carbon, total nitrogen, hydrolysable nitrogen, potassium showed a regular change with the increasing of soil depth.2. The study of artificial robinia and Chinese pine in the Yongshou county on Loess Plateau shows that the mass percent of soil organic carbon, total nitrogen and hydrolysable nitrogen decrease in the order of Chinese pine forest, wasteland and robinia forest, indicating the Chinese pine forest has positive effect on soil organic carbon, total nitrogen and hydrolysable nitrogen compared with pre-afforestation, while the effect of robinia is negative. Before afforestation the locust woodland organic carbon, phosphate and phosphoric mark up separate high quality 14.08%. 9.09%, and 11.92%. The nitrogen, water with nitrogen, potassium and there were reduced 8.16%. 3.31%, and 6%, 3.72%. 14.72% ; Woodland organic carbon and water to nitrogen oxide, and all quality, there were rising 35.92%. 48.98%, and 1.52%, 56.26%.phosphate and potassium and potassium quality scores were reduced 9.28%. 4.47%, and 2.21%. And there is a significant correlation between the mass content of available P and soil depth (P<0.05) and the mass percentage of available P is verified regularly with the increasing of soil depth. By soil degradation index (DI) shows that Pinus increase soil fertility , no significant effect on soil fertility in robinia forest.3. To hu county artificial research shows that organic carbon and water quality to nitrogen oxide, unreclaimed lands, the poplarswere afforested compared with before organic carbon is the soil and water to nitrogen oxide, there are states in containing the effects of 114.69 %.12.9%, and 2.8.The potassium, phosphate and potassium, phosphoric quality scores wasteland >oplars, and as for all afforestation the poplars and there, phosphate and potassium phosphoric quality scores are affected, and reduce 5.99%.3.98%14.84 % and 45.49%.Through the party's analysis and return analysis shows that sex and woodlands are among the nitrogen oxide and water quality scores differentiated remarkable(p<0.05)and rather obvious relevance to the thickness, and deep changes in the soil. By soil degradation index (DI) shows that poplar increase soil fertility.