Effects Of Composted Sewage Sludge On Soil Enzyme Activity And Chemical Properties Of Different Poplar Species

With the local of sewage plant have built one after the other, the number of urban sludge has increased year by year. It is significant issue to handle and use sewage resonably that improves the soil by organic and mineral nutrition matter, for this reason, land utilization considered as a positive and effective method for sludge disposal by home and abroad.This experiment selected Populus canadensis Moench108and Lingfeng3as research object and adopt pot method which used high activity of composted sewage sludge, four treatments were set:control (0t·hm-2, CK), low sludge (15t·hm-2, SS1), middle sludge (30t·hm-2, SS2), high sludge (60t·hm-2, SS3).Reasearch the influence of soil enzyme activities,soil chemical properties and the growth of poplar by different treatments of sewage sluge with two kinds of poplar seedlings and respectively from5th,10th,15th,21th weeks after applied sludge.The main conclusions of the study were as follows:(1) Soil enzyme activity①Populus canadensis Moench108and Lingfeng3indicated the same rule that the soil sucrase activity was increased by the amount of sewage sludge, as well as the addition of the soil sucrase activity was the hightest in15th week, and Lingfeng3exceled than Populus canadensis Moench108.②The soil urease activity of Populus canadensis Moench108and Lingfeng3was increased by the amount of sewage sludge except5th week which indicated Populus canadensis Moench108exceled than Lingfeng3.③Populus canadensis Moench108and Lingfeng3indicated the same rule that the soil alkaline phosphatase activity was increased by the amount of sewage sludge as well as it was little different between Populus canadensis Moench108and Lingfeng3.④Sewage sludge enhanced the soil neutral phosphatase activity in Populus canadensis Moench108and Lingfeng3, and it was the hightest performance in15th week. With the time following, the activity of neutral phosphatase had obvious reduced, as well as Populus canadensis Moench108exceled than Lingfeng3.⑤Sewage sludge enhanced the soil catalase activity which was in relation to the kinds of poplar seedlings. The activity of catalase displayed the highest value by Lingfeng3in15th week, but the activity of catalase displayed the highest value by Populus canadensis Moench108in5th week. At the same time, Populus canadensis Moench108exceled than Lingfeng3.⑥Populus canadensis Moench108and Lingfeng3indicated the same rule that the soil dehydrogenase activity was increased by the amount of sewage sludge, as well as the value of sucrase activity played the highest in10th week and the addition of soil sucrase activity was the hightest in15th week. As well as Lingfeng3exceled than Populus canadensis Moench108.(2) Soil chemical properties①The content of soil total nitrogen, total phosphorus, total kalium, organic matter and available nitrogen was increased by the amount of sewage sludge. The influence of soil total phosphorus and available nitrogen was little diversity and soil total kalium was remarkable diversity (p<0.05) by the two kinds of poplar seedlings, as well as the content of soil total nitrogen and organic matter was decided by the kind of poplar seedlings and seasons.The value of pH was reduced by the amount of sewage sludge which was related by the kinds of poplar seedlings with little diversity except for21th week.②The influence of the content of Fe and Mn was slightly by sewage sludge in soil, but the content of Ca, Pb, Hg, As, Al, Zn, Mg and Cu was decreased by sewage sludge. The content of Fe, Hg, As and Al was higher in Lingfeng3than Populus canadensis Moench108in soil.(3) Poplar growthThe growth of Lingfeng3was promoted in early period and restrained after10days by composted sludge which was benefited by middle sludge (30t-hm"2, SS2). But the growth of Populus canadensis Moench108was restrained by composted sludge which was benefited by low sludge (15t-hm-2, SS1).