Effects Of Water And Fertilizer Coupling Effect On Pinus Tabulaeformis And Sophora Japonica In Daxing Sandy Land Of Beijing

Aiming at the problems of soil which is poor in water and nutrition in sandy land of Beijing Plain.This problem limited the growth of large seedlings after afforestation of ecological forests.In this paper,split plot experiment design method was used to compare Soil and Pinus tabulaeformis growth after applying three irrigation levels and three organic fertilizer.Sophora japonica growth were compared after appliying four irrigation levels and four organic fertilizer application level.The effects of different fertilization and irrigation levels on Soil and tree growth were studied by measuring soil physical and chemical properties,tree height,DBH,chlorophyll and leaf nutrient content.The results are as follows:1.Irrigation and fertilization could significantly increased soil nutrient content.The maximum growth rates of organic matter,total nitrogen and available potassium were 30.2%(A1B2),5.9%(A2B3)and 13.8%(A1B2).Irrigation and fertilization increased the nutrient content in the soil where nutrients are relatively deficient.The growth rate of total nitrogen in deep layer reached 25.3%(A2B3),while the growth rate in surface and middle layer was only-5.75%and 1.1%under the same treatment.The content of available phosphorus and available potassium in surface soil increased more.The growth rates of surface layer and bottom layer reached 40.9%(A2B3)and 24.8%(A2B3),respectively.Under the same treatment,the growth rates of middle layer and bottom layer were 32.4%,-27.7%and-4.0%and-3.2%,respectively.Different nutrient movements in the soil are also affected by irrigation to varying degrees.There was a significant interaction near fertilization and irrigation site.The main effects on nutrient content in different soil locations are different.Fertilization plays a more important role in the location close to the irrigation fertilization site.With the increase of horizontal and vertical distance,the effect of fertilization decreased and the effect of irrigation increased.The coupling effect of fertilization and irrigation on the chemical properties of soil is significant,but the influence on physical properties such as water content is relatively limited,and even a small reduction occurs.The variation of the three factors:-2.7%-1.69%,-1.9%-0.6%,-3.13%-1.27%2.There was no significant interaction between fertilization and irrigation on leaf nutrient and chlorophyll content of Pinus tabulaeformis,but significant interaction on tree height and DBH of Pinus tabulaeformis.Irrigation significantly promoted tree height,new branch length,leaf total P content,leaf total K content,leaf N,P content ratio.Fertilization promoted tree height.However,the effect of high water and fertilizer is not the best.The maximum growth rate of tree height was 9.42%(A3B1),and chlorophyll a content in leaves reached 0.77 mg(g(A3B1).The growth rate of new branch length reached 29%(A3B2)and the total potassium content of leaves reached 22.8g/kg(A3B2).The carotenoid content in leaves was 0.2 mg/g(A3B3).The maximum growth rates of DBH and free height were 23.89%(A2B2)and 9.42%(A2B1),and the total nitrogen content of leaves reached 8.3g/kg(A2B1,A1B2).It could be found that the best promotion treatments occur at high irrigation levels.This result might be due to the excessive pH value of the soil in the experimental plot,and the large amount of irrigation helps to reduce the pH value,thus improving the nutrient absorption of Pinus tabulaeformis3.The effect of low water and low fertilizer on the growth of Sophora japonica was not significant.With the increase of irrigation fertilization,the growth of Sophora japonica is better and better.But for the DBH,tree height,crown width,chlorophyll a and chlorophyll b of Sophora japonica,the effect of mediun water and high fertilizer(A3B4)is the most significant treatment.The growth:rate of tree height,DBH and crown width can reach 16.85%,12.4%.29.99%(E-Yho and 35.03%(N-S).This may be that excessive irrigation will lead to the loss of effective nutrients4.Management and protection of plain ecological forests should consider not only the growth effect of promoting tree growth,but also the efficiency of water and fertilizer utilization and environmental pollution.