In the research,I analyzed the influence on crops caused by different biuret concentrations in compound fertilizers,using pattern of solution culture and potted.In the method of solution culture, 0.5 g(10-8-7) and 1 g(10-8-7)compound fertilizers were added in one litre of water. Thus, the quantity of nitrogen was 56.05 mg/L-1 and 112.1 mg/L-1.And In the method of potted, 0.5 g(10-8-7) and 1 g(10-8-7)compound fertilizers were added in one kilogram of soil. Thus, the quantity of nitrogen was 56.05 mg/kg-1 and 112.1 mg/kg-1. The result of solution culture indicated that there was no toxicity to wheat,corn,tomato and rape when the concentration of biuret was lower than 35,40,20,15 mg per gram of Compound Fertilizer respectively. And the no-toxicity-level to rice was 15 mg biuret in 0.5 gram of compound fertilizer.While in the experiment of potted, no toxicity was detected to wheat,corn,tomato,rape,rice,when the level of biuret was controled under 1.6%,2.0%,2.0%,2.0%,2.0% in their corresponding compound fertilizer respectively. Considering the chlorid were used greatly in the compound fertilizers,the amount of biuret was controled in the one percent.%采用水培和盆栽法,研究了复混肥中不同含量的缩二脲对作物生长的影响.水培施肥水平为每升水溶液中复混肥(10-8-7)含量分别为0.5 g和1.0 g,即每升水溶液中含氮量达到56.05 mg和112.1 mg;土壤施肥水平为每千克土壤中复混肥(10-8-7)含量分别为0.5 g和1.0 g,即每千克土壤中含氮量达到56.05 mg和121.1 mg.水培试验结果表明:每升水溶液中,在适宜各供试作物生长的施肥条件下,复混肥中缩二脲对冬小麦、玉米、番茄、油菜、水稻的毒害作用的临界值分别为35、40、20、15、15 mg.盆栽试验结果表明:在适宜各供试作物生长的施肥条件下,缩二脲对冬小麦、玉米、番茄、油菜、水稻的毒害作用的临界值分别为所施复混肥(10-8-7)含量的1.6%、2.0%、2.0%、2.0%、2.0%.当高于这个临界值时,缩二脲对此5种作物会造成毒害作用.考虑到复混肥的实际制造过程中大量使用含氯化肥,氯离子含量波动大,建议国家在制定复混肥产品标准时缩二脲含量应限制在1%以下为宜.
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