黄土丘陵区不同种植类型梯田2 m土层有机碳的分布特征

为了明确黄土丘陵区梯田种植类型对0—200cm有机碳垂直分布的影响,以甘肃庄浪县堡子沟流域玉米、小麦、土豆、苹果和间作(苹果+土豆)5种典型种植类型梯田的土壤为研究对象,分析土壤有机碳含量、储量在0—200cm的垂直分布特征及影响因素,探讨种植类型对0—200cm土层有机碳分布稳定性的影响。结果表明:(1)5种种植类型梯田的0—200cm土层中,有机碳含量平均为3.33~4.86g/kg,储量平均为8.0~11.69t/hm~2;含量和储量均在间作和苹果地显著高于玉米地、小麦地(P0.05);各样地有机碳含量均表现出明显的层次性,0—20cm显著高于其他各层(P0.05),20cm以下的各层中的变异较小,有机碳储量的垂直分布特征与含量相同,且层次间差异更为显著。(2)土壤有机碳分配比例在0—20cm为17.57%,20—100cm为41.21%,100—200cm为41.22%,种植类型对0—200cm土层有机碳分布稳定性影响较小。有机碳分层比例SR(0—20cm/20—40cm)为1.51~1.78,SR(0—20cm/40—60cm)为1.78~2.02,表明土壤正向发育熟化,土壤质量明显提高。(3)水分能够影响有机碳垂直分布,种植类型对土壤有机碳的深层分布和固存有一定影响,苹果园的发展有利于梯田土壤有机碳的提高。

Distribution Characteristics of Organic Carbon in 2 m Soil Layers Under Difference Planting Types in Terraced Fields on Loess Hilly Region

In order to confirm the effects of planting types on the vertical distribution of soil organic carbon (SOC),five typical planting types of terraces in the Baozigou basin located in Gansu province were studied,which included maize,wheat,potato,apple and intercropping (apple+potato).SOC content,storage and the controls were studied to investigate the effects of planting types on the stability of SOC in 0-200 cm soil layer.The results showed that.(1) The content of SOC in 0-200 cm ranged from 3.33～4.86 g/kg,and the differences among different planting types were significant;SOC in intercropping and apple were significantly higher than those in maize and wheat (P＜0.05);SOC was significant different in different soil layers,and the content of SOC in 0-20 cm soil layer were significantly higher than other layers and the difference were slightly with the soil depth increased.The storage of SOC ranged from 8.0 t/hm2to 11.69 t/ hm2,and the difference was more outstanding among different planting types;specifically,SOC storages in intercropping and apple were significantly higher than those in maize and wheat.(2) The distribution ratio of SOC in 0-20,20-100 and 100-200 cm accounted for 17.57％,41.21％,and 41.22％,respectively.The influences of different planting types on the stability of SOC distribution were small.Among different planting types,the ratio of the SOC storage in 0-20 cm to 20-40 cm soil layer were 1.51～1.78,0-20 cm to 40-60 cm soil layer were 1.78～2.02,which indicates that soil is developing to maturation and soil quality is significantly improved.(3) Moisture has an effect on the vertical distribution of SOC;planting types had certain influences on the distribution and the storage of SOC,the apple orchard of terraced fields in the loess hilly region had a good advantage on the improvement of soil organic carbon in the Loess Plateau.