不同生长年限紫花苜蓿需磷规律及其土壤供磷能力的研究

Patterns of Phosphorus Requirement and Phosphorus Supplying Capacity of Alfalfa Planed Soils in Different Growing Years

2007年5～9月在地处西辽河平原的内蒙古民族大学实验农场对1年生、2年生、3年生、4年生、6年生紫花苜蓿需磷规律及其土壤供磷能力进行了研究。结果表明,紫花苜蓿体内磷含量总体上随着生长年限的增加而降低,尤以第1茬和第4茬更为明显;2年生紫花苜蓿全年磷输出量最高,3年生紫花苜蓿根的磷积累量最高;随着生长年限的增加,紫花苜蓿地土壤速效磷含量总体上呈先降后升的变化趋势,而土壤全磷含量则与之相反。不同种植年限紫花苜蓿地在20～30cm、30～40cm土层内速效磷含量均下降明显。生产中对多年生紫花苜蓿追施磷肥以秋季第3茬刈割后或春季返青前为宜,且宜适当深施。

The phosphorus requirement and soil phosphorus supplying capacity were studied in the treatments of Alfalfa （Medicago sativa L.cv. Algonquin） planted with one-year, two-year, three-year, four-year and six-year on the experimental farm of the Inner Mongolia University for Nationalities in Xiliaohe Plain from May to September in 2007. The results showed that with the increasing of the growing years, the content of phosphorus in the Alfalfa decreased generally, especially in the first and fourth stubble time. The output of phosphorus of two-year alfalfa was the highest. The accumulation of phosphorus in the root of three-year alfalfa was the highest. With the increasing of the growing years, the changing trend of the available phosphorus in the soil decreased first and then increased, but the total phosphorus was different. The available phosphorus in 20 - 30 cm and 30 - 40 cm soil layers in the different planted years decreased obviously. The best times for applying phosphorus fertilizer were after the third stubble in Autumn and before green-turning in Spring.