Characteristics Of Soil Moisture And Nutrients Under Different Vegetation Types Patterns In The Water-Wind-Erosion Crisscross Region Of Loess Plateau

In this study,we studied six vegetation types including Zea mays Linn,weeds,Medicago sativa,Stipa bungeana,Caragana korshinkii and Pinus tabulaeformis in the Water-Wind Erosion Crisscross Region.We focused on the relationship between soil moisture and soil physical/chemical properties under different vegetation types,measured deep soil water contents in 0-600 cm soil layer of six plot types,soil nutrient of 0-100 cm layer and soil bulk density and porosity of 0-60 cm layer.We discussed the effects of different vegetation types on deep soil water content,soil physical and chemical properties.The main conclusions were as follows:(1)In the wet year,the soil moisture content under the cover of different vegetation types changes sharply at 0-200 cm,and in the deeper the soil layer,the soil moisture content changes weaker.After a growing season,the water storage volume of 0-600 cm soil in Zea mays Linn land and abandoned grassland was increased,but the difference was not significant(p>0.05).Soil water storage of 0-600 cm layer of Stipa bungeana land,Medicago sativa land,Caragana korshinkii forestland and Pinus tabulaeformis forestland increased significantly(p<0.05),and the replenishment of soil water storage of Pinus tabulaeformis forestland was the most.(2)Soil dryness occurred in different vegetation types,and the dried grade was different in each month.The dried intensity of Zea mays Linn land was the smallest,the soil dryness degree of abandoned grassland was not significantly different from that of farmland(p>0.05),and the soil dryness of Medicago sativa and Caragana korshinkii was the most serious,which indicated that after returning farmland to forest and grass,abandoned grassland had the best soil moisture storage ability.(3)The soil nutrients of different vegetation types showed that the nutrient content of the shallow soil is higher,and the nutrient content of the deep soil is lower.The total content of organic matter was as follows: Medicago sativa > Pinus tabulaeformis > Caragana korshinkii > Stipabungeana > weeds > Zea mays Linn.On the vertical section,the content of organic matter in 0-40 cm soil layer decreased rapidly,and the decreasing trend of organic matter content in 40-100 cm soil layer slowed down obviously.The soil nitrogen of different vegetation types was mainly accumulated in the soil surface layer at 0-10 cm,and Medicago sativa had an obvious effect on increasing the soil nitrogen content.The replanting and application of organic fertilizer(organic fertilizer and crop stubble)should be encouraged in loess hilly region in order to increase the biomass yield of farmland and improve soil quality.(4)The correlation between soil water content and nutrient in different soil layers was highly different.There was a significant positive correlation between soil water content and porosity in 0-10 cm soil layer(p<0.05).Organic matter was significantly positively correlated with total nitrogen and porosity in 0-60 cm soil layer(p<0.01).Total nitrogen was positively correlated with nitrate nitrogen at 0-10 cm and negatively correlated with ammonium nitrogen(p<0.01).There was a significant positive correlation between total nitrogen and porosity in 10-20 soil layers(p<0.05).Ammonium nitrogen was significantly negatively correlated with porosity in 0-60 cm soil layer(p<0.01),and bulk density was significantly negatively correlated with porosity in 0-60 cm soil layer(p<0.05).