Study on slow release property of melting granulating humic acid urea

Weathering coal was treated with alkaline to get water soluble humic acid and deposition. Weathering coal, humic acid and deposition were compounded with melted urea respectively to produce the three kinds of compound ureas. Slow release properties of the ureas were studied by using the nitrogen soil leaching method. The results show that nitrogen release capacities of all compound ureas are slow except for the urea of adding 10 percent weathering coal, and the release capacity of urea of adding humic acid is lowest. The slow release efficiency of the compound urea of adding 30 percent humic acid is the highest. The slow release capability of weathering coal are different among three kinds of compound ureas, and there is a positive correlation between the slow release capability and the adding amount of humic acid. However, there is poor correlation between the slow release capacity and humic acid adding percent. The compound urea of adding water soluble humic acid has stable quality as a fertilizer. To use water soluble humic acid extracted from weathering coal, and introduce a suitable proportion of the acid and urea could produce humic acid compound urea with a better slow release property.