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標題: | 施用污泥堆肥對土壤碳氮礦化作用與菾菜對氮磷吸收之影響 The Effects of Applying Sewage Sludge Composts on the Soil Carbon and Nitrogen Mineralization and N and P Uptake by Leaf Beet |
作者: | Cheng-Chieh Huang 黃正介 |
指導教授: | 陳尊賢 |
關鍵字: | 污泥堆肥,碳礦化作用,氮礦化作用,菾菜, sewage sludge compost,carbon mineralization,nitrogen mineralization,leaf beet, |
出版年 : | 2010 |
學位: | 博士 |
摘要: | 當污泥進行土地施用時,主要係以滿足作物氮需求而估算施用量,並使地下水體受硝酸鹽污染的風險降低,但污泥的N/P比通常低於作物生長所需的N/P比,此可能導致土壤中磷的累積。因此,本研究選取台北市一都市污水污泥並經堆肥化處理後,與不同性質土壤進行孵育試驗及後續盆栽試驗,目的為評估污泥堆肥中有機碳、氮礦化作用和有效性磷含量的變化,及菾菜(Beta vulgaris L.)對氮磷吸收的影響。
結果顯示,污泥堆肥以25、75及150 Mg ha–1施用量添加至坡堵系(Pu)、三坑子系(Sk)及二林系(Eh)土壤後,CO2釋放速率最高尖峰出現於孵育第3天,之後則迅速下降。Eh土壤有較高的CO2釋放速率,主要為微鹼性的pH值使微生物活性增加,而增加有機物的分解。三個土壤在不同施用量處理中,污泥堆肥的有機碳殘留率約從84-94%,顯示污泥堆肥中之有機碳,大多為較難分解的部分。在無機態氮方面,Pu和Sk土壤中的NH4+–N含量,於孵育開始後快速的增加,且最大量約在孵育的第14–21天間,顯示有機氮的銨化作用的高峰發生於此期間。在Pu土壤中,NO3––N含量於孵育開始後便下降,而Sk和Eh土壤NO3––N含量則隨時間逐漸累積。至孵育結束後,所有施用量處理下,Pu土壤的污泥堆肥淨無機態氮釋出率最低,約在2-3%之間,而三個土壤的污泥堆肥淨無機態氮釋出率皆低於8%。在Pu和Sk土壤中,pH值升高為堆肥中鹼性陽離子的釋放及銨化作用所致,而後續的硝化作用則會使此兩土壤的pH值降低。在Eh土壤中,pH值降低應是由於硝化作用導致酸化的影響,且污泥堆肥施用量愈高,pH值降低的程度就愈大。三個土壤的Mehlich-3萃取磷含量明顯隨施用量而增加,但在孵育期間幾乎無太大變化。 在盆栽試驗中,經菾菜收穫後,三個土壤在施用量以作物氮需求為基準(BN)之處理中,EC值皆高於其他處理,其中以Eh土壤有較明顯的鹽分累積。三個土壤在BN處理中,Mehlich-3萃取磷含量皆顯著(P<0.05)高於其他處理,表示此處理下,土壤中有較高量的磷累積。Pu及Sk土壤的菾菜乾重產量皆以BN處理最高,而在化學肥料(CF)、施用量以作物磷需求為基準(BP)及施用量以作物磷需求為基準並補充氮肥(BP-FN)之處理下,菾菜的乾重產量並無顯著差異。在菾菜氮吸收量方面,Pu及Sk土壤在BN處理下,菾菜對氮的吸收量明顯高於其他處理,而在BP處理中,菾菜則有較低的氮吸收量。Eh土壤在所有處理下,菾菜的氮吸收量均較低於其他兩土壤。其中BN處理的菾菜氮吸收量,與其他兩土壤在同處理下相差最大,原因應是BN處理土壤中鹽分較高,使菾菜生長及對氮的吸收受阻。在菾菜磷吸收量方面,Pu及Sk土壤在BN處理下,磷吸收量皆明顯高於他處理,而Eh土壤在所有施肥處理間則無顯著差異。 Sewage sludge is abundant in nitrogen, phosphorus and other nutrients for plant growth. When sewage sludge is applied to land, the application rate designed to provide the amount of nitrogen needed by crop. However, applying sewage sludge to meet N needs of crops will add excess P result in an accumulation of soil P. Three soils (Pu, Sk, and Eh) were applied with sewage sludge compost (SSC) for laboratory incubation and pot experiments. The aims of the study were to investigate the effect of SSC application on (1) mineralization of organic C and organic N by laboratory incubation experiment, and (2) the uptake of N and P by leaf beet (Beta vulgaris L.) by pot experiment in three soils. The results of incubation experiment indicated that the highest peaks for rate of CO2 evolution occurred at 3 d of incubation in all three soils. The Eh soil revealed the highest rate of CO2 evolution. These results presumably because microbial activity was increased under relatively high soil pH. The percentage of added organic C remained ranged from 84-94% for all treatments at the end of the incubation which suggests that decomposition of SSC might be quite stable. In the Pu and Sk soils, the NH4+–N concentrations were increased rapidly after 3 d of incubation. The maximum NH4+–N concentration was observed at 14–21 d of the incubation, and then gradually decreased as the incubation period progressed. These results suggest that ammonification was occurred in the Pu and Sk soils during the initial incubation period. The percentage of SSC organic N released did not exceed 8% in all three soils at the end of the incubation. This result suggested that the mineralization of organic N was low. In Pu and Sk soil, the pH increase might have resulted from the effect of ammonification of organic N and base cations released in SSC. However, in the Eh soil, soil pH decreased slowly after 3 d of incubation, the decrease in soil pH may be attributed to the acidic effect of the nitrification process. For all treatments, the concentration of Mehlich-3 extractable P remained unchanged during the incubation period. The results of pot experiment showed that the application rate based on N need (BN) treatment resulted in highest soil electrical conductivity and contents of Mehlich-3 extractable P. For Pu and Sk soils, the dry matter yields of leaf beet increased significantly (P <0.05) in BN treatment compared with application rate based on P need (BP) treatment. However, in Eh soil, the dry matter yields of leaf beet were not significantly different in all treatments. In BN treatment, the uptake of N of leaf beet was lower in the Eh soil than in the other two soils. These results presumably because the relatively high EC value led to the disadvantageous effect of the growth of leaf beet. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/45157 |
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