| A great deal of discarded slag was produced in the steal industries in our country.Many of the slag were not used efficiency. To promote the comprehensive utilization of the slag, urea was selected as core and slag were selected as coating material, after the choosing of modifier, size of the slag, type of the slag, study on the technology of the preparation; using water solution, soil column leaching as the method to evaluate the slow release properties of the slag-fertilizer, finally, pot experiment was used to preliminary assess the effect of the slag-fertilizer. it can provide the basis when applied in the agriculture and forestry.The main results were following:1. The effect of water resistance to the binder were compared by formaldehyde and urea which as modifier. The result show: When the proportion of formaldehyde is 2.35%, the water resistance of binder is the lowest, the water absorption is 364%. The water resistance of member is decreased by 35.7%. When the proportion of urea is 1.17%, the water resistance of binder is the lowest, the water absorption is only 152%. The water resistance of member is decreased by73.1%. To increase the water resistance of binder and achieve a good coating effect, 1.2%urea was selected as the modifier of the binder in this paper.2. Orthogonal design was used to investigate the proportion of binder, type of slag and size of slag to the effect of the slag-fertilizer. the coating rate of the four slag-fertilizer were 31.2%,31.2%,28.7%,25.7%,respectively. The nitrogen content of the four fertilizer were 27.5%,18.3%,37.5%,35%,respectively.3. The water solution was used to measure the initial and differential dissolved rate. The result show: the initial dissolved rate of the four slag-fertilizer were 41.5%,75.7%,33.5%,38.9%,respectively. The differential dissolved rate of the four slag-fertilizer were 9.12%,3.55%,6.57&,3.57%,respectively.Meantime, initial and differential dissolved rate of commercial product Oli were 27.7% and 5.50%.The result show: the order of initial dissolved rate was No2 slag-fertilizer> No1slag-fertilizer> No4 slag-fertilizer> No3 slag-fertilizer>Oli. The order of differential dissolved rate was: No1 slag-fertilizer> No4 slag-fertilizer> No3 slag-fertilizer> Oli>No2 slag-fertilizer. The result of the Orthogonal design show that main factor that affects the initial dissolved rate was the proportion of binder.The Orthogonal design show that the main factor that affects the differential dissolved rate was size of the slag. 4. The soil column leaching was used to measure the accumulation of nitrogen of the fertilizer in 30days. The result show: the accumulation of four slag-fertilizer ,Oli and urea were 40.36%,42.06%,46.5%,45.21%,43.32%和60.07%,respectively.So,the slag-fertilizer show certain slow release when compared with urea. Among this, No1 and No3 slag-fertilizer show better leaching effect. The Orthogonal design show that main factor that affects soil column leaching was proportion of binder.5. The nitrogen volatilization reflected the variation of nitrogen of the fertilizer in the soil. The result show that: the accumulation of the four slag-fertilizer ,Oli and urea were 69.97%,75.21%,73.7%%,74.59%,62.29% and 88.41%,respectively.The variation of the pH and urease were measured at the same time, the order of the pH after 30days were: No4 slag-fertilize>urea>No1 slag-fertilize>No2 slag-fertilize>Oli>No3 slag-fertilize. So ,the No3 slag-fertilize show better release property. The Orthogonal design show that main factor that affects nitrogen volatilization was the type of the slag.6. The result of the pot experiment show that rate of the growth of the slag-fertilizer was 105%,-8.75%,86.67%,80.42%,respectively. the rate of the growth of the urea and Oli fertilizer were 50% and 119.37%. The Orthogonal design show that main factor that affects pot experiment was the type of the slag. |
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