北方地区滨海盐渍土型稻田土壤供氮能力的研究

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。

Studies on Nitrogen Supplying Capacity of Paddy Soil of Coastal Saline Soil in the North Area

Nitrogen supplying capacity of paddy soil for rice cultivation of 5 and 30 years were studied by the short-term submerged airtight and leaching incubation method(in constant temperature incubators at 30 ℃) at reclamation from upland(growing Alfalfa) of coastal saline soil in the North Area.The results showed,(1)Soil initial mineral nitrogen of three soils distributed mainly at 0-20 cm soil layer,and the order of soil initial mineral nitrogen concentration was as follows: upland soil > paddy soil of 30 years > paddy soil of 5 years,and 5% significant level was merely found for the paddy soil of 5 years and upland soil of the initial mineral nitrogen concentration.(2)In the same soil layer,the order of soil mineralized nitrogen was: paddy soil of 30 years > upland soil > paddy soil of 5 years.(3)In the same soil layer,the order of soil nitrogen supplying capacity was: paddy soil of 30 years > upland soil > paddy soil of 5 years.Among them,the difference of nitrogen supplying capacity of three soils reached 1% significant level for any two soils at 0-20 cm and 40-60 cm soil layers.For 20-40 cm soil layer,the difference of nitrogen supplying capacity of paddy soil of 5 years and upland soil was not obviously significant.Rice cultivation after reclamation from upland of coastal saline soil could affect not only the soil organic matter(nitrogen) content,but also the quality of soil organic nitrogen,soil nitrogen supplying capacity obviously declined for 5 years rice cultivation,and soil nitrogen supplying capacity obviously increased for 30 years rice cultivation.