Technique Of Planting Alfalfa In Saline-alkali Land In The West Of Songnen Plains

According to the change features of saline-alkali land of Songnen Plains, the research studied thealfalfa varieties, sowing dates and sowing methods for saline-alkali land, analyzing the dynamicchanges of water soluble salt in the soil, and studing the effects of planting alfalfa on soil salinity. Themain results are as follows.1. The germination rate and ratio of seedling height to root length were regarded as two suitableacid and alkali resistance indexes. The germination was inhibited under low or high pH of soil extracts.The proportion of germination in the substrate with pH values from6.43to8.44was higher than60%,and the seedling could grow normally. The critical pH was5.06or9.17, and limiting pH was2.71or10.26through regression equation. The results showed that Zhongmu No.1, Gongnong No.2andHopeland were most acid and alkali resistance. In field trials, the Gongnong No.1, Xinjiang Daye,Gongnong No.2, Gannong No.1and Zhongmu No.1performed well in emergence, growth and regrowthrate.According to the comprehensive performance of each alfalfa varieties in saline-alkali resistanceexperiment conducted in the laboratory and field, Zhongmu No.1and Gongnong No.2had highersaline-alkali resistance of domestic alfalfa varieties.2. The dynamic change trend of water soluble salt content in the soil of experiment area wasmainly decreasing slowly during April to August, while increased rapidly during August to November.The salt content in August was the lowest as0.09%, and in November the highest as1.07%. The pHvalue in the soil had the same dynamic change trend with water soluble salt content, but its variationextent was smaller during April to July.3. It rained more in the experiment area after Mid-June, thus could meet the water needs of alfalfato grow well. And the decrease of the salt content in the soil wsa good for the alfalfa seeds to germinate.Sowing in the ridges could improve the alfalfa’s emergence. According to the climate feature andwater-salt change law in the experiment area, it was supposed to sow the alfalfa in the ridges inMid-June.4. With the growing years of alfalfa increasing, water soluble salt content and soil pH valuedecreased very significantly(P<0.01).Compared with the CK, the contents of total N of each soil layer,had declined and the contents of hydrolytic N, total P and available K of each soil layer had declinedvery significantly(P<0.01) in the seeding year. The contents of organic matter, total P, total N andhydrolytic N were all increased in alfalfa field sown for more than2years.