盐化灰漠土开垦前后碳存贮与碳释放的分层特征

Layered Characters of Organic Carbon Storage and Release in Salinized Gray Desert Soil before and after Reclamation

对盐化灰漠土开垦前后土壤有机碳贮量与碳释放的分层特征进行对比研究。结果表明：与荒漠土壤相比．农田表层（0～20cm）土壤有机碳含量减少了27％，但20～250cm土层有机碳含量与贮量显著增加，使得总有机碳贮量（0～250cm）增加了57％。同时，在0—60cm土层农田土壤碳释放速率也显著高于荒漠，而在底层（60—250cm）两者则无明显差异。农田土壤有机碳在表层以消耗为主；中层（20—60cm）有机碳库受碳存贮与消耗作用的共同控制，但存贮作用更为强烈，该层土壤有机碳量有明显累积；底层（60～250cm）有机碳以存贮为主，较为稳定。此外，荒漠与农田底层土壤有机碳均在65％以上，碳释放比重达到71％，显示了盐化灰漠土底层土壤碳循环的重要性。开垦使得盐化灰漠土土壤碳库表层流失，但全剖面总碳库明显增加。

Some virgin deserts in Xinjiang have been reclaimed as oasis farms. Soil carbon cycle change is resulted in by the change of land use and vegetation. In this paper, a study on the layered characters of organic carbon storage and release in gray dese,rt soil before and after reclamation is carried out. The results show that the organic carbon content in farmland topsoil （0 -20 era） is decreased by 27% compared with that in desert soil, however, the total organic carbon storage along a soil profile of 0 -250 cm in depth is increased by 57%. Moreover, the carbon release from farmland soil of 0 -60 em in depth is obviously higher than that from desert soil, but there is no obvious difference between farmland soil and desert soil in depth of 60 -250 cm. Organic carbon process in farmland topsoil is dominated by consumption; it is jointly affected by organic carbon storage and consumption in soil layer of 20 -60 cm, but the former is higher than the latter, that is the organic carbon accumulation is obvious; and it is dominated by carbon storage in deep soil of 60 -250 cm. Moreover, the organic carbon content in deep soil in both farmland and desert is higher than 65% , the proportion of organic carbon release is as high as 71% , and these reveal the importance of carbon cycle in deep salinized gray desert soil. Reclamation results in the loss of organic carbon in salinized gray desert topsoil, and obviously increase of the total organic carbon storage along a whole soil profile.