坡地黑土團(tuán)聚體氮庫及其分布1)

曹偉　李露　趙鵬志　王恩姮

(東北林業(yè)大學(xué)，哈爾濱，150040)

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坡地黑土團(tuán)聚體氮庫及其分布1)

曹偉李露趙鵬志王恩姮

(東北林業(yè)大學(xué)，哈爾濱，150040)

摘要為了研究黑土區(qū)不同土地使用類型團(tuán)聚體氮庫及其分布，以東北黑土區(qū)坡耕地、退耕還落葉松林地、樟子松人工林地土壤作為研究對象，結(jié)合不同坡位，對不同粒徑團(tuán)聚體內(nèi)氮質(zhì)量分?jǐn)?shù)及總儲量進(jìn)行對比分析，結(jié)果表明：坡耕地以>2 mm粒徑土壤團(tuán)聚體為主，達(dá)到50%以上，樟子松人工林地、退耕還落葉松林地以<2 mm粒徑土壤團(tuán)聚體為主；各土地利用類型<0.5 mm粒徑的土壤團(tuán)聚體含氮質(zhì)量分?jǐn)?shù)均較高，但儲量較低，坡下和坡中下的儲量高于其他坡位；坡耕地各徑級團(tuán)聚體氮質(zhì)量分?jǐn)?shù)及總儲量均為最低，總體氮庫由小到大表現(xiàn)為坡耕地、退耕還落葉松林地、樟子松林地。坡耕地團(tuán)聚體及氮庫的再分布印證了耕作侵蝕的存在，退耕還林能夠有效恢復(fù)黑土區(qū)氮庫、維持碳氮平衡。

關(guān)鍵詞黑土；土壤團(tuán)聚體；氮儲量；坡位；退耕還林

分類號S153.6+2；S714

Organic Nitrogen Pool and Its Distribution of Aggregates in Sloping Black Soils//

Cao Wei, Li Lu, Zhao Pengzhi, Wang Enheng

(Northeast Forestry University, Harbin 150040, P. R. China)//Journal of Northeast Forestry University，2016,44(5)：63-66.

Aiming to understand the distribution pattern of nitrogen pool of sloping lands in the black soil region of Northeast China, sloping farm land, larch forest land converted from farm land, andPinussylvestrisforested land were selected to analyze characteristics of nitrogen content and storage of different aggregate sizes and slope positions for the quality assessment of black soil. The farm land was mainly composed of aggregates bigger than 2 mm, reaching more than 50%. On the contrary, larch forested land andP.sylvestrisforested land were composed of aggregate smaller than 2 mm. Nitrogen content within <0.5 mm aggregates was higher for all three lands comparing to aggregates with bigger size, while nitrogen storage was lower because of its lower composition percent, and nitrogen storage in middle-down and down slope position was relatively higher. Nitrogen content and storage of sloping farm land was the lowest, with ascending order of farm land, larch forested land, andP.sylvestrisforested land. The results confirmed the existence of tillage erosion in this region, and converting cultivated land into forest could be an effective way to regenerate soil nitrogen pool and maintain carbon-nitrogen balance of black soils.

KeywordsBlack soil; Soil aggregate; Nitrogen storage; Slope position; Converting cultivated land into forest

土壤中的氮素是作物所需的大量營養(yǎng)元素之一，影響作物的產(chǎn)量和品質(zhì)[1]；在耕作過程中由于管理不善也使其成為農(nóng)區(qū)最重要的非點源污染物，耕地氮素流失現(xiàn)象嚴(yán)重,尤其導(dǎo)致坡耕地土壤氮儲量的失衡[2-3]。東北黑土區(qū)作為我國重要的商品糧生產(chǎn)基地，研究坡耕地、林地條件下土壤氮素分布對黑土資源的保護(hù)和退化黑土的恢復(fù)具有重要的現(xiàn)實意義，同時能夠為黑土侵蝕與流失規(guī)律提供證據(jù)。

土壤團(tuán)聚體對保持土壤結(jié)構(gòu)、維持水熱氣肥的動態(tài)平衡具有重要作用[4]。不同土地利用類型，即不同生態(tài)系統(tǒng)內(nèi)土壤團(tuán)聚體的分布差異較大，進(jìn)而影響到團(tuán)聚體內(nèi)部元素的轉(zhuǎn)化速率，由此可見，不同徑級團(tuán)聚體內(nèi)氮素形態(tài)與儲量也必然存在差別[5-6]。王曉燕[7]等研究表明，在單一土地利用結(jié)構(gòu)中,林果地地表徑流中的溶解態(tài)氮濃度要比坡耕地低，林地對地表氮素的截持效率更高；同……