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Bfof Effect of plastic-sheet -covered cultivation on yield of Maize (Zeamays L. ) was studied. The results showed that plastic-sheet-covered cultivation has the effects on increasing soil temperature and soil water retention. The numbers of bacteria, actinomycetes, and fungi were higher in plasctic-sheet-covered soils than that in uncovered soils. The numbers of bacteria and actinomycetes increased with corn growing, but that of the fungi changed in vise versa. In addition, the plastic-sheet... Bfof Effect of plastic-sheet -covered cultivation on yield of Maize (Zeamays L. ) was studied. The results showed that plastic-sheet-covered cultivation has the effects on increasing soil temperature and soil water retention. The numbers of bacteria, actinomycetes, and fungi were higher in plasctic-sheet-covered soils than that in uncovered soils. The numbers of bacteria and actinomycetes increased with corn growing, but that of the fungi changed in vise versa. In addition, the plastic-sheet provided a proper condition for soil organisms and increased the amounts and activities of soil Enzyme. Therefore, nutrient transformation was accelerated and soil fertility was improved. The plastic-sheet-covered treatment provided a suitable soil ecological condition for corn yields increasing. 本试验对玉米地膜覆盖增产机制进行了研究,结果表明:地膜覆盖具有增温保墒的作用,同时在地膜覆盖条件下土壤中细菌、放线菌、真菌等数量增加,其中细菌、放线菌的数量随玉米生育期的推进逐渐增多,而真菌的数量则逐渐减少。另外,地膜覆盖为土壤微生物的活动提供了有利条件,从而使其数量增多,活性增强,同时各种土壤酶活性提高,加速土壤养分转化,提高土壤有效养分含量,为玉米增产打下了良好的土壤生态学基础。 This paper deals with the characteristics of phosphorus in the long-term plastic film mulching soil (a loamy brown earth derived from loesslike parent material ) at Shenyang Agricultural University in 1987 ̄1992. The main results showed that more phosphorus was uptaken by plant and little accumulated in covered plots. The amounts of soil inorganic and organic phosphorus were reduced in the covered treatments, cspecially the Al-P and moderately liable P, whereas the Fe-P and Ca-p increasedto some extent.... This paper deals with the characteristics of phosphorus in the long-term plastic film mulching soil (a loamy brown earth derived from loesslike parent material ) at Shenyang Agricultural University in 1987 ̄1992. The main results showed that more phosphorus was uptaken by plant and little accumulated in covered plots. The amounts of soil inorganic and organic phosphorus were reduced in the covered treatments, cspecially the Al-P and moderately liable P, whereas the Fe-P and Ca-p increasedto some extent. The capabilities of adsorption and conservation for added phosphorus declined in the shceted treactments but the esorption was enhanced, which could increase the effcetivness of phosphorus in these treatments. In addition, the application of organic material and manure could improve the levels of phosphorus in the plots covered with plastic film. 本文采用对比法对沈阳农业大学长期(1989~1992)地膜覆盖定位试验地棕壤中磷素的平衡与变化情况进行了全面研究.结果表明:覆膜之后土壤磷移出量增多而积累量减少。地膜覆盖降低了土壤无机磷和有机磷的含量,其中下降幅度最大的是Al-P形态磷和中等活性有机磷;而Fe-P和Ca-P形态磷含量有所提高.覆膜后土壤中吸附磷和保持磷的数量下降,而解吸磷能力增强、试验结果还表明增施有机肥能显著提高上壤有机磷和无机磷的含量以及提高磷的解吸能力,增加幅度最大的是Al-P和中等活性有机磷。因此,增施有机肥是恢复和提高覆膜后土壤磷素肥力的较好措施。 This experiment was conducted in a loamy brown earth derived from loesslike parent material at Shenyang Agricultural University during 1987 ~ 1994. The main results showed that the average contents of alkali-hydrolyzable-N (1mol NaOH-N) and aminoacid-N in all covered treatments declined 6.46mgkg-1 and 21.6mgkg-1, compared with uncovered treatments. However, no significant effect was found on total N, NO3-N tended to be accumulated in the top layers of the plots covered with the plastic film,... This experiment was conducted in a loamy brown earth derived from loesslike parent material at Shenyang Agricultural University during 1987 ~ 1994. The main results showed that the average contents of alkali-hydrolyzable-N (1mol NaOH-N) and aminoacid-N in all covered treatments declined 6.46mgkg-1 and 21.6mgkg-1, compared with uncovered treatments. However, no significant effect was found on total N, NO3-N tended to be accumulated in the top layers of the plots covered with the plastic film, because of much water with soluble NO3 moving toward these top horizons. Soil biomass-N increased greatly by covering practice, which could lead to the improvement for soil nitrogen supplying ability. In addition, the application of organic manure could improve the levels of total N, alkali-hydrolyzable-N, NO3 -N and organic components of nitrogen in soil. Therefore, more manure should be applied to soil covered with plastic film so as to improve covered soil fertility. 定位试验结果表明,长期地膜覆盖对棕壤全氮影响较小,而碱解氮含量平均下降6.46mg/kg。覆膜土壤上层NO~-_3—N含量明显增加。有机氮各组分在覆膜条件下发生较大变化,其中氨基酸态氮的绝对和相对数量下降显著,各处理平均下降21.6mg/kg和2.0%。覆膜使土壤微生物体氮量增加。试验结果还表明,施用有机肥和化肥都能提高土壤全氮、碱解氮、NO~-_3—N和有机氮的含量,施用有机肥明显地提高了微生物体氮的含量,是培肥覆膜土壤氮素肥力的有效措施。
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