Effects of different kinds of sludge on nutrient supply for rice and beans

This article is concerned with the authors' study on the effects of different kinds of sludge on the nutrient supply for rice and beans in Putian context. To test the effects of the different kinds of sludge on the soil of the paddy fields, we have taken fresh sludges supplied by a sludge processing plant in Putian as samples to test the yields of rice and beans before and after their use. Particularly, tests were done with the different effects of different kinds of sludge, such as dry sludge, organic fertilizer and biological fertilizer on the soil absorption and supply of N, P and K. The results of our experiments show that the use of sludge as a kind of fertilizer helps to increase quick absorption of N, P and K by the soil. In case of rice absorption of N, P, and K, the increase rates can be 3.74 g/plant, 0.45 g/plant and 4.83 g/plant respectively, with 4.76%, 15.4% and 14.5% as increase rates of yields as compared with the soil without such supply. As to beans, the increase rates are 15.2%, 14.6% and 13.7% respectively. If dry sludge is taken as sample fertilizer, the increase rates of rice and bean yields are 56.9 g/plant and 29.4 g/plant , with an increase of 13.4% and 6.1% respectively. The results also prove an extra-salience in rice yield and a salience in beans'. Among the three kinds of fertilizer, biological fertilizer ranks the highest, organic fertilizer in the middle and dry sludge the lowest. This article also give some insights into how to make sludge more useful as a kind of agricultural resources and brought about the ideas of composite process of sludge when turning the sludge into organic fertilizer or biological fertilize.