海河流域14种农作物对土壤库中磷的输出量和输入量初步研究

 海河流域14种农作物平均含磷量为0.127±0.053%，变化范围0.023—0.214%，不同器官中最高可达0.419%，最低仅为0.019%。对土壤库中磷输出量最大者为谷子，磷可达99.758±56.931kg·ha-1·a-1，其次是玉米和棉花；磷输入量以白薯为最大，为12.557±5.020kg·ha-1·a-1(但包括可食部分块根的输出部分在内)，然后是谷子和花生，其余作物均较低，<2kg·ha-1·a-1。具高输出量的作物的部位有玉米、谷子、花生、棉花等果实，谷子、花生、白薯等茎叶；就输入量而言，除白薯为高输入和谷子为低输入类型外，其余均属很低输入型，上述特点揭示了海河流域因作物的收获而大量损失土壤库中的磷，如种植谷子、玉米、棉花等分别以99.758、32.661和26.591kg·ha-1·a-1的速率损失有效态磷。并对不同子流域作物磷的输出(入)量差异以及针对上述问题应采取的对策作了探讨。

A PRIMARY STUDY ON THE OUTPUT AND INPUT OF PHOSPHORUS IN 14 CROP FIELDS IN THE HAIHE RIVER BASIN. NORTH CHINA

1. The average concentration of P in the tissues of the 14 crops of the Haihe River Basin was 0.127%, varying from 0.023% to 0.214%. The highest P concentration in different organs of the 14 crops was 0.419%, while the lowest was 0.019%.2. Of the 14 crops in the Haihe River Basin, Panicum miliaceum had the highest P output (removal in the harvested parts) from the soil pool, being 99.758±56.935kg·ha-1·a-1 followed by Zea mays and Gossypium hirsutum. Ipomoea batatas could be considered to be the greatest P contributor to the soil pool (the returning rate averaging 12.557kg·ha-1·a-1, but including the edible parts), followed by Zea mays and Arachis hypogaea. Most of the other crops contributed a very small amount of P to the soil, generally less than 2 kg·ha-1·a-1.3. The fruits of Zea mays, Panicum miliaceum, Arachis hypogaea, Gossypium hirsutum and some others, and the stems or stems plus leaves of Zea mays, Arachis hypogaea and Ipomoea batatas and so on were the main P output carriers. The low P input rates of most crops grown in the Haihe River Basin suggested that a largeamount of P was removed with the harvested parts.4. The P outputs in the corn fields of different subsidiary river basins of the Haihe River Basin were different, in the order. Daqing River Basin> Chaobai River Basin>Zhangwei River Basin>Haotuo River Basin>Yongding River Basin.5. Our results show that the P removal by harvested crop parts was 22 times of the P returned, suggesting that if the straw was not returned, growing Panicum miliaceum, Zea mays and Gossypium hirsutum would result in P losses of 99.758, 32.661 and 26.591 kg·ha-1·a-1 respectively. To maintain the soil fertility, P fertilization or returning straw to the field are recommended. The farmers, however, have only paid attention to P fertilization, but have ignored the straw-returning method that is considered to be a very effective way to recycle not only P, but also other essential elements as well.