滨海风沙地龙眼园土壤特性的研究

STUDY ON THE PROPERTIES OF COASTAL SANDY SOIL IN EUPHORIA LONGANA PLANTATION

滨海风沙地土壤结构性差（物理性沙粒占９２．１１％一９３．３３％），质地疏松（通气孔隙占３４．４８％一３６．７８％），氧气充足，有利龙眼菌根生长；沙地夏秋土温高，温差变幅大，持续时间久，对幼根生长有害，克服措施是盖草降温和浇灌．而３５ｃｍ以下沙层温度终年适宜龙眼根系的生长。风沙地渗漏性大、蓄水力差、有机质贫乏（０．６０％）、各种营养元素含量低；经过耕作培肥改土，土壤养分水平迅速提高，土壤速效养分的增加和土壤微生物量和土用酶活性有着密切关系。在一年中土壤各元素含量的变化是冬高夏低．夏季表土上层臣元素含量都低于表土下层，雨量多和灌水是主要原因。

oastal sandy soil can not form an aggregate structure (physical sand 92. 11%一93. 33%).The soil is loose (aeration porosity 34. 48%一36. 78%)with sufficient O_2 for thegrowth of Euphoria longana's mycorhiza. The high soil temperature with a wide variation insummer and autumn are harmful to the growth of the longana young roots. Covering the soilwith straw and applying a proper irrigation will protect the young roots from a heat injury。The sandy soil has a high permeability a low moisture holding capacity, a lack of organicmatter(0. 603%)and ,nutrient elements . of content of nutrients in the soil can be increasedby ctiltivation and soil reclamation . The.increase in soil nutrients are closely related to thequantity of micrlbe and the enzyme activity of the soil. The content of nutrient elements inwinter is highcr than that in summer .Furthermore,in summer. the content of soil nutrientelements is lower in a surface .stratum than in a subsurface stratum because of abundant rain- fall and frequent irrigation。