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侵蚀对紫色土坡耕地土壤有机碳库变化的影响
Alternative TitleSoil erosion effects on soil organic carbon pools in mountainous region slope farmland of northern Sichuan, China
Language中文
樊红柱
Thesis Advisor张建辉
2016
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Name博士
Degree Discipline土壤学
Keyword耕作侵蚀 137cs 坡耕地 有机碳及其组分 空间分布
Other Abstract

水土流失导致土壤退化,严重威胁着农业可持续发展。目前国内外有关耕作侵蚀对坡耕地土壤有机碳组分影响的研究报道较少。本研究选择短坡耕地、长坡耕地、梯坡耕地及无侵蚀的对照样地为研究对象。利用野外测量,137Cs示踪及统计分析等方法,开展侵蚀对坡耕地土壤有机碳组分作用机制研究。主要结果和结论包括:1、坡耕地土壤侵蚀的空间分布格局坡面土壤再分布是耕作侵蚀和水蚀共同作用的结果。短坡地耕作侵蚀对总土壤侵蚀的贡献率为90.56%、长坡地为45.51%、梯坡耕地为82.78%,说明短坡地和梯坡以耕作侵蚀为主,长坡地耕作侵蚀与水蚀相当。梯坡田埂上侧坡地的底部对田埂下侧顶部存在土壤补给。短坡地、长坡地及独立梯田坡上137Cs随土层深度增加呈降低趋势,坡下则相反。表明坡耕地坡下部位明显的土壤埋藏特性。2、坡耕地土壤有机碳空间分布特征坡地土壤沉积区SOC储量显著高于侵蚀区;独立梯田坡地内SOC储量坡上显著低于坡下。与对照SOC储量比较,短坡地的上坡和中坡降低了72.21%,下坡提高了21.72%;长坡地0~5 m部位降低了18.07%,其他位置增加了24.37%;梯坡的上坡、中坡部位分别降低了7.49%和110.09%,下坡增加21.80%。说明土壤侵蚀改变了SOC空间分布。短坡地上坡和中坡SOC含量随土层深度增加先增加后降低,下坡则随土层深度而降低;长坡地SOC含量随土层深度增加而降低;短坡地和长坡地土壤侵蚀区SOC含量深度分布不满足对数回归方程[y=aLn(x)+b],土壤沉积区满足该方程;梯坡耕地SOC含量深度对数分布规律不明显。3、坡耕地土壤活性有机碳组分变化侵蚀坡地土壤沉积区水溶性碳、微生物量碳、氧化活性碳和CMI显著高于侵蚀区;梯坡独立梯田内沿坡这些指标均增加;梯坡田埂上侧坡地的底部这些指标明显高于田埂下侧顶部,除了第2阶梯田。与对照比较,短坡地坡上水溶性碳和活性碳降低了26.02%和64.55%,坡下提高了45.23%和28.47%,微生物量碳均低于对照;长坡地水溶性碳提高了71.55%,微生物量碳和活性碳降低了59.19%和19.42%;梯坡水溶性碳增加了29.89%;上坡和中坡微生物量碳和活性碳降低30.92%和51.23%,下坡增加了5.92%和23.65%。侵蚀区氧化活性碳含量深度分布不满足对数经验公式,而土壤沉积区完全满足对数经验公式。4、坡耕地土壤团聚体有机碳组分变化侵蚀坡地坡上以1~0.5 mm或0.5~0.25 mm水稳定性团聚体为主,坡下以>5 mm或1~0.5 mm为主;无侵蚀对照以>5 mm和5~2 mm团聚体为主;说明耕作侵蚀倾向于破坏水稳性大团聚体,相应增加微团聚体。短坡地和长坡地0~30 mm位置土壤有机碳主要储存于<0.25 mm微团聚体中,长坡地30~35 m位置有机碳主要固持在>5 mm和5~2 mm团聚体中;梯坡土壤有机碳主要储藏于1~0.5 mm和0.5~0.25 mm团聚体中;无侵蚀对照土壤团聚体主要储存于>5 mm和5~2 mm团聚体中。说明强烈侵蚀区有机碳主要固持于小团聚体中,而土壤沉积区主要固存于大团聚体中。5、坡耕地土壤不同大小颗粒有机碳组分变化侵蚀坡地和无侵蚀对照样地土壤组分以砂粒或粗粉粒为主;同一位置土壤细粉粒、粗黏粒和细黏粒中碳含量高于砂粒和粗粉粒;而粗粉粒碳储量相对较高。说明侵蚀对土壤中不同大小颗粒组分、碳含量与储量分布结构影响不大。短坡地有机碳主要分配到细黏粒,而长坡地、梯坡耕作及对照样地主要分配到粗粉粒。说明侵蚀明显影响有机碳在土壤颗粒中的分配比例。6、侵蚀对土壤有机碳库的影响机理所有类型坡耕地土壤水溶性碳、微生物量碳与SOC呈正相关,SOC和氧化活性碳与CMI也存在着正相关关系。土壤侵蚀导致水溶性碳、微生物量碳、氧化活性碳及SOC沿坡增加。土壤侵蚀引起>5 mm和5~2 mm团聚体组分沿坡增加,而0.5~0.25 mm和<0.25 mm团聚体组分沿坡降低。土壤SOC含量与砂粒组分呈正相关,而与粗粉粒、粗黏粒、细黏粒呈负相关。坡耕地土壤沉积区不同大小颗粒中SOC含量高于侵蚀区。

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Mountainous region of slope land in purple soil is one of the most serious soil erosion areas inChina. And soil erosion results in soil degradation, this phenomenon are a major threat to sustainable agricultural production. Few studies have examined the effects of tillage erosion on soil organic C and fractions in purple soil. Three sloping cultivated landscapes and one no erosion control were selected from experiment site located in Jiange County, Sichuan Province. The field survey, 137Cs tracing and geostatistics analyses were used to examine the impacts of tillage erosion on soil organic C and fractions in purple soil. The main results and conclusions are as follows:1. Soil spatial redistribution as affected by tillage erosionBoth water erosion and tillage erosion contributed to soil redistribution on the slope farmland in mountainous area of northern Sichuan.Tillage erosion rates accounted for 90.56%, 45.51% and 82.78% of total erosion rates for the short, long and terrace farmland, respectively. Tillage erosion was mainly responsible for soil loss at the short slope and terrace farmland; water erosion played a primary role in soil loss at the long slope field.Soil redistribution pattern at the neighbor land of terrace were that there was soil replenishment from upside to downside of the ridge at the terrace farmland. There was an obvious spatial correlation among 137Cs of different soil layer, contents of 137Cs reduced with soil depth increase at the top slope position, but on the opposite at the lower position. This suggested that soil was buried at the bottom slope position.2. Spatial variation of SOC as affected by tillage erosionStorages of SOC remarkably increased along transect of the slope on the cultivated land. And storages of SOC at the top position were higher than that at the lower position at the independence slope of terrace farmland.On the short sloping cultivated land, SOC inventories in the top and middle position decreased, with the mean decrease of 72.21%, but increased 21.72% in the low position, compare with the control.SOC storage in the 0-5 m position of the long slope land decreased 18.07% than control, but SOC storage in others positon were higher than control, with a mean increment of 24.37%. On the terrace land, SOC inventories in the top and middle position decreased 7.49% and 110.09%, respectively, but increased 21.80% in the low position, compare with the control. On the short slope land, SOC content at the top and middle positions were increased, and then decreased, but always reduced at the lower position with the soil layer increased. SOC content in the different position of the long slope farmland redeced with the soil depth increased. This phenomenon attributed to erosion process dominated by water or tillage erosion. The depth distribution of SOC for soil deposition area can be described by the formula [Y=aLn(X)+b]on the sloping cultivated lands, but it did not follow this formula for soil erosion area and terrace field.3. The changes of soil labile organic C as affected by tillage erosionAt the soil deposition area, contents of soil soluble organic C, microbial biomass C, oxidative labile organic C and CMI were higher than these at soil erosion area in the different style slope farmlands. Those indexes of upside ridge were also higher than those of downside the ridge at the terrace land, except for the second filed. Compare with the control, contents of soil soluble organic C and microbial biomass C decreased 26.02% and 64.55% at the top position, and increased 45.28% and 28.47% at the low position, respectively, on the short sloping cultivated land. On the long slope land, content of soil soluble organic C was increace 71.55% compare with the control, but concentration of microbial biomass C and oxidative labile organic C increased 59.19% and 19.42%, respectively. Soil soluble organic C content was higher in the terrace land than in the control. Contents of microbial biomass C and oxidative labile organic C at the top and middle position of terrce filed were decrease of 30.92% and 51.23%, respectively; but increased 5.92% and 23.65% at the low position.The depth distribution of oxidative labile organic C for soil deposition area can be described by the formula [Y=aLn(X)+b] on the sloped farmland, but it did not follow this formula for soil erosion area. 4. The changes of soil aggregate organic C fractions as affected by tillage erosionAt the different style slope land, soil aggregates proportion of 1-0.5 mm and/or 0.5-0.25 mm was the highest at the upside slope position, and the proportion of >5 mm and/or 1-0.5 mm was the highest at the downside slope position.Soil aggregates was almost size of >5 mm and 5-2 mm with water sieving on the control field.The findings suggest that soil erosion tend to break down macro-aggregates, and fine in micro-aggregates.At the short slope and 0-30 m position of the long slope land, SOC mainly laid in <0.25 mm size aggregates. But SOC of 30-35 mm position at the long slope farmland stored in the size of >5 mm and 5-2 mm size aggregates. At the terrace land, SOC mainly stored in 1-0.5 mm and 0.5-0.25 mm size aggregates. And SOC mainly stored in the size of >5 mm and 5-2 mm size aggregates on the no erosion filed.Our results suggest that SOC mainly reserve in the micro-aggregates size for soil erosion area, but store in the macro-aggregates size fractions for soil deposition area.5. The changes of soil particle-sized fractions as affected by tillage erosionSoil particle-sized fractions were mainly dominated by sand or coarse silt.Organic C concentration in fine silt,coarse clay and fine clay size fractions was higher than that in sand and coarse silt at all style slope farmlands.Organic C storages of coarse silt size fractions were the biggest among allsoil particle-sized fractions. This founding suggested that soil erosion had little effect on the C content and storage of soil particle-sized fractions. In the short slope land,proportions of SOC in fine clay size fractions were higher than others, but coarse silt size fractions in the long, terrace and control lands were bigger. This suggested that soil erosion effected rates of SOC in particle-sized fractions.6. Relationships between SOC pools and137Cs of slope farmlandsThere was a positive linear correlation between content of soil soluble organic C and microbial biomass C and SOC content, a strong linear correlation was also observed between SOC content and the concentration of oxidative labile organic C and CMI on the all style cultivated land. Soil erosion decreases soluble organic C, microbial biomass C, oxidative labile organic C and SOC content and increases their spatial variations on the eroded sloping cultivated lands, with the same trend of 137Cs along the the transect slope lands. Soil erosion increased the weights of >5 mm or 5-2 mm size soil aggregates and decresed the weights of 0.5-0.25 mm or<0.25 mmsize soil aggregates. There was a positive relationship between C content and the weight of sand particle-sized fraction. But opposite trends were found between coarse silt, coarse clay and fine clay size fractions. SOC content of particle-sized fractions for soil deposition area were higher than that for soil erosion area. 

Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/18894
Collection山地表生过程与生态调控重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
樊红柱. 侵蚀对紫色土坡耕地土壤有机碳库变化的影响[D]. 北京. 中国科学院大学,2016.
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