海河流域不同植物砣含量、地域分异及其输入、输出量研究

海河流域是我国农业发展的一个重要基地,由于不合理开发利用,造成某些地区土壤出现贫瘠化、盐渍化和沙漠化,土壤缺磷也很明显.为了寻找植物对磷的需求特点以及海河流域土壤磷分布规律,可以从植物指示的角度研究不同地区不同植物磷含量特征及其差异,研究植物每年从土壤中输出和输入的磷总量,从而寻找农业生态系统磷循环规律并科学指导施肥.

THE PHOSPHORUS CONTENTS, GEOGRAPHICAL DISTRIBUTION, AND ITS OUTPUTS AND INPUTS BY PLANTS IN THE HAIHE RIVER BASIN, NORTH CHINA

Among the 61 species in the Haihe River Basin, Artemisia scoparia Wald-et Kitaib has the highest phosphorus content, Lemna minor L. the lowest, with total phosphorus content being 2.12 mg·g^-1 and 0.43 mg·g^-1, respectively. The average phosphorus content of Zea mays L., Sorghum vulgare Pers, Panicum milliaceum L, Oryza sativa L,Tritium qestivum L. and Amena nuda L. is<2.00 mg·g^-1 which is less than that of the normally growing crops. The phosphorus contents of different vegetation types are as following: halophilous plants>natural grasses>crops>vegetables>broadleaf trees>shrubs and mid-shrubs>needleleaf trees>water plants. The phosphorus content varies in different areas of the basin.The grain has the highest phosphorus content among the different parts of crops, then the leaf and stem, while the root the lowest, with the contents being 2.34, 1.61, 1.11 and 0. 84mg/g respectively. The output of phosphorus by the crop harvest from the soil is 22 times more than that of input.It makes soil lose its available phosphorus at the speeds of 44.85 kg/hm²·a, 32.66 kg /hm²·a, and 26.59kg /hm²·a for the fields of Panicum miliaccum L., Zea mays L. and Gossypium hirsutum L.It is proposed to apply phosphours fertilizer and return straws to the field.