Effects Of Different Organic Fertilizers On Pear Tree Growth And Soil Property

Pear production is the third fruit industry in China and developing rapidly in recent years. However, pear yield is often impaired due to extensive management, maladjusted water and fertilization, deficient control of plant diseases and insects. To improve the orchards fertility, supply of nutrition to trees, and pear yield and quality, the fertilizers input and nutrients availability in soil were investigated in the pear orchards around Bohai Bay.15year old’Huangguan’pear trees and10year old ’Hoshui’pear trees were selected to study the influence of different organic fertilizers and fertilization management on soil property, tree growth, root distribution and pear yield. The results are as follows:On an average, the content of soil organic matter (SOM) was17.1g·kg-1in pear orchards around Bohai Bay and the highest content of SOM was22.9g·kg-1in Liaoning province. The average content of available nitrogen (AN), phosphorus (AP) and potassium (AK) in this region were70.0mg·kg-1,63.1mg·kg-1and176mg·kg-1, respectively. Soil acidification in this region was distinct, soil pH in50%pear orchards was found lower than6.0. The comprehensive evaluation of soil nutrient showed that the pear orchards in Liaoning province had the highest soil nutrient level while that in Hebei province had the lowest. The limiting factors were OM, AN and pH. The total applicated fertilizer rate of N, P2O5and K2O in main pear orchards of Shandong province were968,441and523kg·hm-2, respectively, and the chemical fertilizer input possessed the largest proportion. The similar fertilization model was also found in Heibei Province. NPK compound fertilizer was used at about94%and66%respectively in Shandong and Liaoning province. Urea was dominantly applied in Hebei province, accounting77%of the total applied chemical fertilizer.Application of organic fertilizer enhanced the leaf area, weight of100leaves and length of new shoots of15year old’Huangguan’pear trees. Meanwhile, the contents of fruit soluble solid, soluble sugar and ratio of total sugar to organic acids was also improved, especially by the treatment of Bio-organic fertilizer with PGPB (BOF1). The fruit weight and yield with treatment BOF1were increased by17.4%and33.9%in comparison with the control.Different organic fertilizer treatments could improve the soil microbial quantity, content of soil microbial biomass carbon (SMBC) and soil microbial biomass nitrogen (SMBN) during the whole growth period, compared to treatmentof control and traditional fertilizer (TF). The mineral nitrogen in soil was mainly made up of nitrate. It decreased gradually during the pear growth period, especially at the second expanding stage of pear. At pear maturity stage, the content of nitrate in soil with BOF1treatment was significantly higher than that of the other treatments.The biomass of leaves increased slowly during the early period of growth and then increased quickly later. The biomass of fruits increased quickly with the fruit expendation. During the development of leaf, contents of N, P and K declined, and kept stable in the late period, except K. The content of N, P and K in fruits decreased from setting fruit to harvesting stage. The accumulation of N, P and K in leaves decreased first and then increased. The accumulation of N, P and K in fruits increased gradually and P, K decreased between100days and120days after bloom. Application of organic fertilizer increased the contents and accumulations of N, P and K in leaves and fruits. Treatment BOF1exhibited the best efficiency and CF followed.The roots of10year old’Houshui’pear trees distributed in the range of0-60cm below the soil surface at the vertical direction and0-60cm from the stem at the horizontal direction. The root length density of Grade I (0-1mm) and Ⅱ (1-3mm) distributed in the range of40～80cm below the surface at the vertical direction and30～90cm from the stem at the horizontal direction.The root length density of Grade Ⅲ(>3mm root diameter) distributed in the range of0-40cm below the surface at the vertical direction and0-60cm from the stem at the horizontal direction. The density of root length and surface area in the treatment of BOF1and BOF2was larger than Control in most soil masses.Besides that, the largest density of root length and surface area in treatment BOF1and BOF2distributed in the range of60～90cm from the stem at the horizontal direction. The amount of earthworm in treatment BOF1was larger than Control and distributed at depth of20～60cm and radius of60！90cm from the stem.The results provided theoretical guideline for fertilization depth and location in pear orchards.