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東北黑土氮素轉化和酶活性對水熱條件變化的響應

發(fā)布時間:2018-03-12 23:36

  本文選題:黑土 切入點:干濕交替 出處:《東北師范大學》2015年碩士論文 論文類型:學位論文


【摘要】:東北黑土區(qū)位于溫帶半濕潤季風氣候區(qū),其氣候特點是冬季寒冷干燥、夏季雨熱同期。在長達半年的冬春季節(jié)里,土壤處于凍結和解凍狀態(tài),存在明顯的季節(jié)性凍融現(xiàn)象;而夏季雨熱同期導致農田土壤濕度變化頻繁,干濕交替現(xiàn)象普遍存在。凍融和干濕交替過程是黑土區(qū)土壤中氮素遷移轉化的重要外營力之一,也是黑土區(qū)土壤物質流和能量流變化的重要驅動力。本論文以東北黑土區(qū)黑土為研究對象,采用室內模擬試驗的方法,研究不同濕度、不同頻度干濕交替過程以及長期自然凍融和短期頻繁凍融作用對土壤氮素轉化及土壤酶活性的影響,初步揭示2種水熱條件變化對土壤氮素轉化影響的微觀作用機理。研究結果如下:1、含水量的影響。在相同培養(yǎng)時間,含水量為20%土壤的銨態(tài)氮和硝態(tài)氮含量低于含水量為35%和60%的土壤,而氮素轉化速率則隨著土壤含水量的增加而增加,且隨著培養(yǎng)時間的延長,氨化、礦化及硝化速率均呈下降趨勢;隨著培養(yǎng)時間的增加,脲酶活性呈大幅度變化后波動性變化的趨勢,轉化酶活性呈現(xiàn)波動性變化,但不同含水量對土壤脲酶和轉化酶活性的影響差異不顯著。2、干濕交替的影響。在培養(yǎng)期間,對照組與處理組土壤銨態(tài)氮及硝態(tài)氮含量整體呈下降趨勢,但與對照組相比較,干濕交替作用促進了銨態(tài)氮和硝態(tài)氮含量的增加;經歷干濕循環(huán)的實驗組氮素轉化速率整體上高于恒定含水量的對照組,且隨著培養(yǎng)周期的增加,氮素轉化速率先大幅度下降,隨后呈波動性變化;受土壤含水量和干濕循環(huán)的影響,除了第0.5、3周期實驗組脲酶活性低于對照組外,剩余培養(yǎng)周期里的脲酶活性均表現(xiàn)為:實驗組對照組;轉化酶活性也表現(xiàn)出相同的變化規(guī)律(8周期除外)。3、短期凍融的影響。整個培養(yǎng)期間,凍融作用下的土壤銨態(tài)氮和硝態(tài)氮含量隨著培養(yǎng)時間的增加而增加。除了培養(yǎng)1周期內低強度凍融(-10—5℃)的土壤銨態(tài)氮含量最低外,剩余培養(yǎng)周期里,銨態(tài)氮含量均表現(xiàn)為低強度凍融(-10—5℃)高強度凍融(-25—5℃)對照組(5℃),不同凍融溫度作用下硝態(tài)氮含量差異明顯。與對照組相比較,凍融交替降低了土壤的礦化速率和硝化速率,提高了土壤的氨化速率,氮素轉化速率對不同強度凍融響應顯著,總體上看,土壤氨化速率表現(xiàn)為:低強度凍融高強度凍融對照組。受土壤溫度和凍融交替的影響,土壤脲酶活性和轉化酶活性均低于對照組,且兩種酶活性均表現(xiàn)為低強度凍融高強度凍融(1周期除外)。4、長期凍融的影響。長期自然凍融有利于銨態(tài)氮含量的積累,而硝態(tài)氮含量表現(xiàn)為下降趨勢。隨著凍融時間的增加,土壤氨化速率和礦化速率表現(xiàn)為相似的增長趨勢,而土壤硝化速率在整個室外凍融期間表現(xiàn)為負增加。和對照土壤相比較,含水量較高的3號平行樣品的土壤脲酶活性和轉化酶活性有一定的提高,其余兩個平行樣品的土壤脲酶活性和轉化酶活性均有不同程度的下降。5、懫用Pearson的雙因素相關性分析得到,除了在不同含水量狀況下,其與銨態(tài)氮相關性不顯著,短期凍融處理下,其與礦化速率相關性較差外,土壤中氮素轉化的相關指標與脲酶活性均有顯著相關性。而轉化酶活性除了在干濕交替狀況下與氮素轉化的相關指標相關性不顯著外,不同含水量及凍融交替作用下的土壤氮素轉化速率和凍融循環(huán)的無機氮(銨態(tài)氮、硝態(tài)氮)與轉化酶活性的相關性均較好。綜上,干濕交替和凍融交替兩種水熱條件變化對土壤氮素轉化和土壤酶活性均有重要影響。
[Abstract]:The black soil region of Northeast China is located in the temperate semi humid monsoon climate zone, its climate is cold and dry in winter, hot summer rain period. In over half of the winter season, the soil in freezing and thawing condition, there are obvious seasonal freeze-thaw phenomenon; summer rain heat over the same period in the farmland soil moisture changes frequently, the phenomenon of the wet dry freeze thawing process. Alternate nitrogen in black soil area in migration is one of the important forces of transformation, is also an important driving force of soil material and energy flow of change. The black soil region of Northeast China as the research object, using the method of indoor simulation experiment, study different humidity, different frequency and alternate process the long-term natural freeze-thaw and frequent short-term effects of freezing and thawing on soil nitrogen transformation and soil enzyme activity, revealed 2 hydrothermal conditions on soil nitrogen transformation The micro mechanism of the influence. The results are as follows: 1. The influence of water content. At the same time of culture, 20% moisture content of soil ammonium nitrogen and nitrate nitrogen content is lower than the water content is 35% and 60% of the soil, and nitrogen conversion rate will increase with the increase of soil moisture, and with the culture time the extension, ammonification, mineralization and nitrification rate decreased; with the increase of culture time, the urease activity showed a significant change after the volatility change trend, the invertase activity showed fluctuation, but the effect of water content on soil urease and invertase activity had no significant difference.2, influence of wetting. During the incubation period, the control group and the group of soil ammonium nitrogen and nitrate nitrogen content decreased, but compared with the control group, wet dry alternation promotes the increase of ammonium nitrogen and nitrate nitrogen content; dry wet cycle real experience The experimental group on the whole nitrogen conversion rate was higher than that of the control group with constant water content, and with the increase of the culture cycle, nitrogen transformation rate first decreased, then fluctuated; affected by soil moisture and the effect of dry wet cycle, but lower than that in group 0.5,3 the urease activity cycle in the control group, the remaining urease activity cycle. The training are as follows: the experimental group control group; invertase activity also showed the same variation (8 cycles except).3, the short-term effects of freezing and thawing. During the whole incubation period, freezing and thawing of soil ammonium nitrogen and nitrate nitrogen content increased with incubation time. In addition to training cycle 1 in low intensity freeze-thaw (-10 - 5 DEG C) the soil ammonium nitrogen content was the lowest, the remaining period of cultivation, the content of ammonium nitrogen showed low intensity freeze-thaw (-10 - 5 DEG C) high strength and freeze-thaw (-25 - 5 DEG C) and control group (5 C), different freeze-thaw temperature With the content of nitrate nitrogen significantly. Compared with the control group, alternate freezing and thawing reduced mineralization rate and nitrification rate of the soil, improve the soil ammonification rate, nitrogen transformation rate of different intensity freeze-thaw response significantly, on the whole, the soil ammonification rate as follows: freeze-thaw control group low intensity freeze-thaw high strength. Affected by soil temperature and freezing thawing effect, urease activity and invertase activity in soil were lower than the control group, and the two enzyme activities were low intensity freeze-thaw high strength (1 freeze-thaw cycle except.4), the long-term effects of freezing and thawing. The long-term natural freeze-thaw is conducive to ammonium nitrogen content the accumulation, and the nitrate nitrogen content was decreased. With the increase of freezing thawing time, soil ammonification rate and mineralization rate showed a similar trend, while the soil nitrification rate during freezing thawing showed a negative increase in the outdoor and compared to control soil, The soil urease activity and invertase activity of high moisture content of the 3 parallel samples has been improved to a certain extent, the remaining two parallel samples were the soil urease activity and invertase activity decreased.5, Zhi with two factor Pearson correlation analysis, except in different moisture conditions, and ammonium nitrogen the correlation is not significant, short-term freeze-thaw treatment, the mineralization rate and poor correlation, correlation index of nitrogen transformation and soil urease activity had significant correlation. The invertase activity in addition to no significant correlation in the condition of relevant indicators under the dry wet alternate with nitrogen transformation, different water content and freeze-thaw cycles under the action of the soil nitrogen conversion rate and freezing thawing cycle of inorganic nitrogen (ammonium and nitrate) correlation with invertase activity was obtained. To sum up, and freezing and thawing cycles of two kinds of water and heat conditions change on the wet dry Soil nitrogen transformation and soil enzyme activity have important effects.

【學位授予單位】:東北師范大學
【學位級別】:碩士
【學位授予年份】:2015
【分類號】:S155.27

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