Effect Of Different Vegetation Restoration Patterns On Soil Aggregates And Microbial Biomass In The Arid Area Of Northern Weihe River Basin

The effect of two typical vegetation restoration patterns(artificial alfalfa grassland and artificial locust forest) on soil physical and chemical properties, soil microbial biomass, soil aggregates microbial biomass were conducted in the Arid Area of Northern Weihe River Basin. Taken the natural grassland and agricultural useland as control, the soil was divided into four levels which were <0.25 mm, 0.25~1 mm, 1~2 mm and > 2 mm by the dry sieve method. The results were given in the following.1. The artificial alfalfa grassland and artificial locust forest could improve soil quality and reduce soil bulk density. The soil bulk density of different vegetation restoration were among 1.21~1.38 g·cm-3. The 0~20 cm layer was not significant, but significant in the layer of 20~40 cm. The soil bulk density was generally performed as alfalfa grassland > farmland > natural grassland > artificial loadcust forest. The soil water content of both artificial alfalfa grassland and artificial locust forest decressed with the increase of number of recovery years, indicating that water was an important limiting factor to vegetation restoration in the Arid Area of Northern Weihe River Basin. Therefore, we should pay full attention to the water supply during recovery of ecological environment in the Arid Area of Northern Weihe River Basin.2. Soil aggregate content varies as the shape of “V”, <0.25 mm micro aggregates and > aggregate content of 2 mm was the main component, while the proportion of middle grasin size was low. Planting alfalfa and locust could significantly reduce the soil microaggregates and then promote the aggregating of the soil. The aggregating of surface soil of alfalfa and locust was better than natural grassland and agricultural land and the large aggregates becoming stable with the increasing depth of soil.3. Different years of alfalfa and locust vegetation recovery patterns could significantly improve soil quality, especially the soil fertility. The soil organic matter was significantly correlated with total nitrogen, so were total phosphorus and available phosphorus, available phosphorus and available potassium(P<0.01); There was significant active correlation ship among soil microbial biomass carbon and soil organic matter, total nitrogen, so was total nitrogen and microbial biomass nitrogen(P<0.05). The correlation between soil microbial biomass carbon and nitrogen under different vegetation restoration patterns always reached significant level(P<0.01). Compared with organic matter, total nitrogen, the soil microbial biomass carbon and nitrogen could reflect the change of soil quality more sensitively. Therefore, they should be valued as the important factor to compare the different vegetation restoration in the Arid Area of Northern Weihe River Basin.4. The soil quality of alfalfa grassland under different recovery years performed as the trend up-down with the increasing recovery years, and the effects reached best at the 11 years. The soil quality of the locust forest performed similar as alfalfa grassland and the best recovery effect happened on the 21 years. So it’s better to do some artificial intervention after 11 years in alfalfa grassland to prolong the life of the grassland and performed some reasonable intervention or use on the locust forest after 21 recovery years in the Arid Area of Northern Weihe River Basin.