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采用短期淹水密闭淋洗培养法(恒温30℃),研究北方地区滨海盐渍土型旱地土壤(种植苜蓿草)开垦种植水稻5年和30年稻田土壤供氮能力。结果表明:(1)3种土壤初始矿质氮主要分布在0~20 cm土层,且土壤初始矿质氮含量的高低顺序为旱地土壤>30年稻田土壤>5年稻田土壤;5年稻田土壤与旱地土壤之间初始矿质氮含量差异达5%显著水平。(2)相同土层,土壤矿化氮量高低顺序为30年稻田土壤>旱地土壤>5年稻田土壤;任意2种土壤之间矿化氮量差异均达1%显著水平。(3)相同土层,土壤供氮能力大小为30年稻田土壤>旱地土壤>5年稻田土壤;其中,在0~20 cm和40~60 cm土层,任意2种土壤之间供氮能力差异均达1%显著水平,在20~40 cm土层,30年稻田土壤与旱地土壤、5年稻田土壤之间供氮能力差异均达1%显著水平,而旱地土壤与5年稻田土壤之间供氮能力则无明显差异。这表明滨海盐渍土型旱地土壤开垦种植水稻后,不仅影响了土壤有机质(氮)含量,而且也影响了土壤有机氮品质,种植水稻5年使土壤供氮能力显著下降,而种植30年使土壤供氮能力显著上升。
The short-term flooding closed leaching culture (constant temperature 30 ℃) was used to study the soil nitrogen availability of paddy soils cultivated in paddy soil of northern coastal saline soil cultivation (planting alfalfa). The results showed that: (1) The initial mineral N in the three kinds of soils mainly distributed in 0 ~ 20 cm soil layer, and the order of the initial mineral N in the soil was dry land> 30 years paddy soil> 5 years paddy soil; The difference of the initial mineral nitrogen content in upland soil reaches 5% significant level. (2) In the same soil layer, the order of soil mineralized nitrogen is 30 years of paddy field soil> dry land soil> 5 years paddy soil; and the difference of mineralized nitrogen between any two kinds of soil reaches 1% significant level. (3) In the same soil layer, the capacity of soil nitrogen supply was 30 years of paddy soil> dry land soil> 5 years of paddy soil. Among them, in the 0-20 cm and 40-60 cm soil layers, The differences were both significant at 1% level. The differences in nitrogen-supplying abilities between soil layers in 20-40 cm soil layer, 30-year paddy soil and upland soil, and 5-year paddy soil all reached 1% significant level, while that in upland soil and 5-year paddy soil No significant difference between nitrogen capacity. This indicates that the reclamation and cultivation of paddy soils on coastal saline soil not only affected the content of soil organic matter (N), but also affected the quality of soil organic nitrogen. After five years of planting rice, soil nitrogen availability decreased significantly, but planting for 30 years Soil nitrogen availability increased significantly.