【作者】 陈露；

【导师】 沈禹颖；

【作者基本信息】 兰州大学 ， 作物栽培学与耕作学， 2010， 硕士

【摘要】 黄土高原地区是我国乃至世界上典型的生态脆弱区,特有的自然地理条件及以谷物生产为主的单一农业系统引致的水土流失和肥力下降受到了广泛关注,多年生牧草形成根系能力强,有利于土壤有机碳的储存和固定。为评价多年生牧草在甘肃庆阳黄土高原的固碳效果,本研究于2007年6月至2008年6月,对多年生草地0-10 cm土壤全碳(TC)、有机碳(SOC)含量,>0.25mm颗粒有机碳(POC)、可溶性有机碳含量(DOC)、易氧化有机碳(EOC)含量、碳库管理指数(CPMI)、有机碳矿化速率常数(SOCM)等进行了比较研究,以冬小麦田为参照：1.苜蓿、红豆草、三叶草、百脉根、美国香豌豆、无芒雀麦等牧草单播种植5年后,0-5cm土壤TC含量为19.28 g/kg-25.42 g/kg, SOC含量为9.84 g/kg-16.10 g/kg, DOC含量为33.82 g/kg-40.58 g/kg, EOC含量为9.65 g/kg-13.4 g/kg,比对照冬麦田分别提高21%-52%,34%-120%,17%-40%,61%-123%；至5-10 cm层,各项指标依次为16.42g/kg～18.55 g/kg,7.84 g/kg～10.04 g/kg,28.59 g/kg～38.06 g/kg,88～8.58 g/kg,分别比对照冬麦田提高2%～11%,18%-51%,11%-45%,4-51%。2.苜蓿、红豆草与无芒雀麦等组成的不同混播组合中,0-5 cm土壤TC、SOC、POC、EOC含量分别为17.91 g/kg-21.97 g/kg,9.93 g/kg-11.33 g/kg,5.00 g/kg-4.06 g/kg, 8.71 g/kg～10.15 g/kg,较对照冬麦田提高7%-31%,35%-54%,45%-115%,59%～69%；至5-10 cm土壤,上述指标较对照冬麦田提高1%～38%,36%-78%,169%-336%,33%-69%,以POC提高幅度为甚,POC、DOC和EOC碳的变化相对于SOC更为敏感。栽培草地TC含量在0-10cm内随深度的增加而减少,而冬麦田则随深度的增加而增加,耕作使TC的空间分布趋于均衡。3.三叶草草地0-10 cm土壤有机碳密度在7个种单播中最高,为1.41 kg／m2,以百脉根最低为1.05 kg／m2,对照冬麦田为0.95 kg／m2；混播牧草地以无芒雀麦+苜蓿+红豆草组合含量最高,为1.36 kg／m2,比冬麦田提高23%,多年生栽培牧草有利于土壤有机碳密度的增加。4.单播草地0-5 cm CPMI比冬麦田高出81%-179%,以三叶草为最高,百脉根为最低,至5-10 cm层,7个单播草地比冬麦田高出51%-114%；混播牧草地土壤碳库管理指数比冬麦田高出42%-105%,多年生栽培牧草显著提高土壤碳库管理指数,利于土壤固碳。5.0-10 cm土壤全氮含量与土壤全碳、总有机碳含量、易氧化有机碳含量之间呈显著正相关性。6.经170天室内培养,0-10cm土壤有机碳矿化累积释放量均以冬麦田最低,0-5 cm层有机碳矿化累积释放量比5-10 cm高13%-30%,具明显空间分布,而冬麦田则趋于稳定大致为0.77 mg C/g-0.87 mg C/g;单播牧草有机碳潜在矿化量C0为1.670 mgC/g-2.989 mg C/g,混播牧草地则为1.354～1.510 mg C/g,冬麦田C0为0.86 mg C/g。多年生牧草地表层土壤有机碳潜在矿化量均高于冬麦田,有机碳矿化速率常数均低于冬麦田,说明冬麦田土壤潜在可矿化量碳含量虽少,但矿化速率常数较大,对土壤碳的固定能力低于多年生牧草地。更多还原

【Abstract】 The Loess Plateau features unique geographical conditions. The soil erosion and fertility degradation of the region has been recognized worldwide, which have predominately arisen as a result of a long history of traditional grain crop farming systems. Perennial pasture has the proven ability to form extensive root systems, with the benefits of soil organic matter storage and sequestration. In order to evaluate the carbon sequestration effect of perennial pasture in the region, an experiment was conducted from June 2007 to June 2008. Soil total carbon (TC), soil organic carbon (SOC),＞0.25 mm particular organic carbon (POC), dissolved organic carbon (DOC), easily oxidized organic carbon (EOC), CPMI and soil organic carbon mineralization speed constant in pure and mixed perennial pastures were measured and compared to that of winter wheat:1. Soil TC in the 0-5 cm layer from pure cultivated lucerne, sainfoin, clover, crowtoe, sweet pea and brome grass pastures after five years was found to be 19.28 g/kg～25.42 g/kg, SOC was 9.84 g/kg～16.10 g/kg, DOC was 33.82 g/kg～40.58 g/kg, EOC was 9.65 g/kg-13.4 g/kg, values which were 21%～52%,34%～120%,17%～40%,61%～123% higher than winter wheat respectively; In the 5-10 cm soil layer, each index were 16.42 g/kg～18.55 g/kg,7.84 g/kg～10.04 g/kg,28.59 g/kg～38.06 g/kg,5.88 g/kg～8.58 g/kg respectively, which were 2%～11%,18%～51%,11%～45%,4%～51% higher than winter wheat respectively.2. In the mixed-pasture containing lucerne, sainfoin and brome grass, soil TC, SOC, POC and EOC in the 0-5 cm layer were 17.91 g/kg～21.97 g/kg,9.93 g/kg～11.33 g/kg,5.00 g/kg-4.06 g/kg,8.71 g/kg-10.15 g/kg respectively,7%～31%,35%～54%,45%～115 %,59%～69%higher than winter wheat; In 5-10 cm layer, the indexes above are 1%～38 %,36%-78%,169%-336%,33～69%higher than that of winter wheat, with POC having the largest range. POC, DOC and EOC are more sensitive than SOC. The TC content under cultivated pasture in 0-10 cm layer decreased with depths, but under winter wheat increased with depths. Cultivated pasture led the space distribution poise.3. In the 0-10 cm soil layer, soil organic carbon density content under clover pasture was 1.41 kg/m2 which was the highest in the seven single-spices sowing forages where as for crowtoe it was found to be 1.05 kg/m2 which was the lowest. Winter wheat was 0.95 kg/m; Brome grass+Lucerne+sainfoin was 1.36 kg/m2, which was 23% higher than winter wheat and is the highest of mixed-spices sowing forages, leading to the conclusion that perennial pasture is superior for soil organic carbon storage.4. In the 0-5 cm soil layer, the CPMI in single-spices sowing of forages was 81%～179% higher than winter wheat soil. The highest was clover, the lowest was crowtoe. In the 5-10 cm layer, the CPMI in single-spices sowing of forages was 51%～114% higher than soil under winter wheat; the CPMI in the soil of single-species sowing of forages was 42 %～105% higher than winter wheat. Perennial pasture significantly increased the CPMI, which is preferable for soil organic carbon storage.5. In the 0-10 cm soil layer total nitrogen was significant correlated with soil total carbon, soil organic carbon and easily oxidized organic carbon.6. After 170 days of incubation in the lab, for the 0-10 cm soil layer, the organic carbon mineralization release capacity under winter wheat was the lowest; the 0-5 cm layer was 13%～30% higher than 5-10 cm layer. There was significant space difference, but winter wheat was 0.77 mg C/g～0.87 mg C/g; Soil organic carbon potential mineralization capacity was 1.670～2.989 mg C/g under single-spices sowing of forages, whereas under mixed-spices sowing of forages it was 1.354 mg C/g～1.510 mg C/g; in winter wheat, soil organic carbon mineralization potential was 0.86 mg C/g. The soil organic carbon mineralization capacity is higher in perennial pasture than winter wheat, soil organic carbon mineralization speed constant is lower than winter wheat, leading to the conclusion that the capacity of soil storage of carbon is lower in winter wheat than perennial pasture.更多还原