滨海沙滩造林种果后土壤理化性质的变化

在滨海沙滩营造木麻黄防护林，林带老化后进行更新，部分林地改种潮州柑或芒果而成为果园，并于其间套种农作物或牧卓；结果表明，人为耕作活动对土壤的热化起到了明显的促进作用．在造林种果的同时，大量肥料的施入及优质客土改良了土壤，使＞１．０ｍｍ的砂粒比例明显减少，＜０．０１ｍｍ的粉粘粒及土壤养分含量明显增加，其中沙草地、防护林及果园，０—４０ｃｍ土壤粉粘粒含量分别为５６．４ｇ／ｋｇ、５９．６ｇ／ｋｇ和１０８．９ｇ／ｋｇ，土壤有机质为０．７１ｇ／ｋｇ、２．０２ｇ／ｋｇ和４．１１ｇ／ｋｇ；土壤氮素含量随有机质提高而提高，柑园速效磷和钾含量是沙草地的３７倍和３．５倍，然而防护林的种植对土壤速效磷和钾的影响却不明显；由于雨水淋洗，土壤盐分减少；又由于酸性化学肥料的大量施入，土壤ｐＨ值由８．３下降为５．３．果园的营建，明显改善了土壤的肥力状况及其保水保肥性能，提高了沙滩地的利用价值及生态经济效益．

Effect of Afforestation and Planting Fruit Trees on Soil Physical and Chemical Properties of Coastal Sandy Land

The cultivation practices play a great role in amelioration of sandy soil.In the 6 planting models surveyed, the sand content(>1.0mm) was evidently reduced, and silt content(<0.01mm) increased as a result of the applications of large amount of fertilizer and fertile guest soil. At the depth of 40cm of soil, the average silt contents of sandy grass land, protective forestbelt, and fruit orchard were 56. 4g/kg, 59. 6g/kg,and 108. 9g/kg, and soil organic matter contents of the three types of land were 0. 71g/kg, 2. 02g/kg, and 4. 11g/kg,respectively. From the sandy grass land outside the shelterbelt to fruit orchard inside the shelterbelt, soil organic matter and nitrogen content were increased, but the available Kwas declined. meanwhile the PH was decreased from 8. 3 to 5. 3. Afforestation and planting fruit trees at the coastal sandy land largely improved the soil fertility status and water-holding capacity as well as utilization value of sandy land.