| The straw mulching experiment was carried out in southern pear orchard in Yongzhou city, Hunan province, the typical southern region, in order to study the change of soil temperature, soil moisture, soil fertility and physical properties, quantity of soil microbe, nutrient content of pear tree, fruit quality and fruit yield after the orchard was covered by straw mulch. Results from the research showed that straw mulching could improve conditions of soil moisture, nutrient, air, temperature and heat, soil microbe and fruit quality and fruit yield. The comprehensive effect of straw mulching on southern pear orchard was apparent.Straw mulching had apparent effects on adjustment to soil temperature. The effect of apparently increasing soil temperature could alleviate or avoid the damage to roots, particularly those in the top soil layer, caused by exceeding low temperature in winter. Straw mulching could effectively decrease the frequency of high soil temperature and the possibility of damage to roots caused by high temperature in summer, which prompted the growth of roots and the absorption of soil nutrient, soil water.Straw mulching increased soil moisture in pear orchard, especially in July, August when there was lack of rainfall in southern region, the effect of water storage and water conservation was apparent. The effect of straw mulching on soil moisture differed in different depth of soil, generally is better in lower soil layer. It came to the conclusion that compared to ck the water storage of 0~20cm soil layer with straw mulching increased 16 to 16.2 percent, whereas that of 40~60cm soil layer merely increased 7.1 to 8.0 percent.Straw mulching increased the content of soil organic matter in pear orchard, but the changes of total N> total P> total K were not obvious. The increase of available nutrient was apparent, compared to ck there was a 157 percent increase in available P, and a 71 percent increase in available K. In addition, straw mulching decreased soil bulk density, increased field moisture capacity and soil porosity, thus ameliorated soil fertility and physical properties in pear orchard.Straw mulching improved the quantity of soil microbe and activity of soil microbe. In 0~ 40cm soil layer the bacteria increased 150.99%, the ammoniation bacteria 142.24%, the nitrogen-fixing bacteria 95.47%, and the fungi the smallest, 56.33%. During the pear trees growing periods, there were more soil microbe in the straw covered pear trees than that in the uncovered field. Straw mulching, furthermore, prompted the appearance of ammoniation bacteria ahead of time.Straw mulching enlarged the size of pear leaf, improved the proportion, the chlorophyll content and the chlorophy11 a/b of fresh pear leaf, thus improved photosynthesis of pear leaf,prompted the growth and development of pear tree. Straw mulching increased the content of nutrient elements of pear leaf, which ameliorated the nutrient conditions of pear tree.Straw mulching prompted the growth of pear fruit, increased the weight of singe fruit and the yield of single pear tree. It, moreover, improved the ratio of sugar to acid, ameliorated the flavor of pear, and eventually improved the quality of fruit. |
