不同恢复措施对宁夏荒漠草原土壤碳氮储量的影响

以放牧(CK)、深翻耕(S)、浅翻耕(Q)、免耕(M)和封育(F)5种不同生态恢复措施处理的荒漠草原为对象,研究不同恢复措施条件下0~40 cm土层土壤有机碳,全氮储量的变化特征。结果表明,0~10 cm和10~20 cm土层,有机碳含量均以浅翻耕处理草地最高,分别为14.90和14.50 g·kg^-1,显著高于深翻耕处理草地、封育草地和放牧草地(P<0.05);20~30 cm土层,不同处理草地有机碳含量变化范围为5.03~9.93 g·kg^-1,以浅翻耕处理草地最高,封育草地最低(P<0.05)。土壤全氮含量,0~10 cm和10~20 cm土层均以浅翻耕处理草地最高,分别为0.17和0.22 g·kg^-1,显著高于封育和放牧草地(P<0.05);20~30 cm和30~40 cm土层均以深翻耕处理草地最高,分别为0.14和0.13 g·kg^-1,显著高于封育草地(P<0.05)。不同处理草地各土层土壤有机碳和全氮密度的分布范围为0.49~1.58 kg·m^-2和0.013~0.039 kg·m^-2,其中,0~40 cm各土层有机碳密度及0~10 cm和10~20 cm土层全氮密度均以浅翻耕处理草地较高,封育草地较低,20~40 cm土层全氮密度以深翻耕处理草地最高,封育草地较低。0~40 cm各土层土壤有机碳和全氮储量均以浅翻耕处理草地最高,分别为47.72和1.09 t·hm^-2,显著高于封育草地(P<0.05)。浅翻耕处理草地更有利于该区荒漠草原土壤有机碳和全氮储量的积累。

Effects of different restoration measures on the soil organic carbon and nitrogen reserves in a desert steppe grassland ecosystem in Ningxia

This study investigated the changes of soil organic carbon and nitrogen in a desert steppe ecosystem in Ningxia under grazing (CK) and different vegetation restoration regimes, which included deep ploughed (S), shallow ploughed (Q), no-tillage (M) and enclosed (F). Soil samples were collected from 0-10 cm, 10-20 cm, 20-30 cm, and 30-40 cm soil depths. The results showed that the soil organic carbon contents were significantly greater (P<0.05) in the shallow ploughed treatment (14.90 and 14.50 g·kg^-1 in the 0-10 cm and 10-20 cm soil layers, respectively) than those in deep ploughed, enclosed and grazing treatments. For the 20-30 cm soil layer, the organic carbon content in the different treatments ranged from 5.03 to 9.93 g·kg^-1, and was highest in the shallow tillage treatment and lowest in the enclosed treatment (P<0.05). The total nitrogen (TN) contents for the 0-10 cm and 10-20 cm soil layers were both highest in the shallow ploughed treatment (0.17 and 0.22 g·kg^-1, respectively), and they were significantly higher (P<0.05) than those in the enclosed and grazing treatments. For the deeper soil layers, the total nitrogen contents were highest in the deep ploughed treatment (0.14 and 0.13 g·kg^-1, respectively, for 20-30 cm and 30-40 cm soil depths), while those in the enclosed treatment were significantly lower (P<0.05). Expressed on an area basis, the soil organic carbon densities in different soil layers of the various treatments ranged between 0.49 and 1.58 kg·m^-2, while the total nitrogen densities ranged from 0.013 to 0.039 kg·m^-2. The soil organic carbon densities at each depth of 0-40 cm layer and the total nitrogen densities at 0-10 cm and 10-20 cm were higher in the shallow ploughed and lower in the enclosed treatment. The total nitrogen densities for the 20-40 cm soil depth were highest in the deep ploughed and lowest in the enclosed treatment. For the 0-40 cm soil depth, the soil organic carbon and total nitrogen reserves in the shallow ploughed treatment were 47.72 and 1.09 t·ha^-1, respectively, and were significantly higher than those in the enclosed treatment (P<0.05). Thus, the shallow ploughed treatment is the most conducive among the tested treatments for accumulation of soil organic carbon and nitrogen reserves in desert steppe grassland of this region.