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Accueil du site → Doctorat → Chine → 2011 → Effect of Agricultural Land Utilization on Soil Respiration and Organic Carbon Storage in the Loess Plateau China

Lanzhou University (2011)

Effect of Agricultural Land Utilization on Soil Respiration and Organic Carbon Storage in the Loess Plateau China

陈先江;

Titre : Effect of Agricultural Land Utilization on Soil Respiration and Organic Carbon Storage in the Loess Plateau China

Auteur : 陈先江;

Grade : Doctoral Dissertation 2011

Université : Lanzhou University

Résumé
Greenhouse gas emissions from grassland ecosystems have severely impacted on the global climate changes and have become one of the key issues of science. Grassland ecosystems are important terrestrial ecosystems and are intensively affected by human activities. In this study, the Loess Plateau was choosing as the study site and five agrosystems were selected as objects of study. We determined the soil respiration dynamics, soil organic carbon, soil total nitrogen, soil total phosphorus and soil water content and ananysed environmental and biological factors which affect soil respiration and its relationships. The main factor which influenced the soil respiration was confirmed and quantized changes of soil organic carbon, soil total nitrogen, soil total phosphorus, annual soil CO2 emission and Q10 value. The main results are as following:1. Soil respiration characteristics and carbon emission of agrosystems on the Loess Plateau(1) Daily variations of soil respiration. Soil respiration was higher associated with chages of soil temperature at 5 cm depth. The peak and minmum values of soil respiration and soil temperature were observed synchronous. The peak value of soil respiration appeared at between 12:00-16:00 and the minmum values were observed at between 01:00-06:00.(2) Seasonal variations of soil respiration. The series of soil respiration of agrosystems were ranged:August> May> December.(3) Daily soil CO2 emission. The series of daily soil respiration were ranged : silvo-pastoral (2.51 g C m-2)> alfalfa pasute (2.34 g C m-2)> agroforestry (1.84 g C m-2)> rangeland (1.69 g C m-2)> cropping land (1.31 g C m-2).(4) Annual soil CO2 emission. The highest and lowest soil C emission period were summer and spring, respectively, in the year. The series of annual soil CO2 emission among the agrosystems were ranged:silvo-pastoral (582.2 g C m-2)> alfalfa pasture (485.8 g C m-2)> agroforestry (379.1 g C m-2)> rangeland (332.9 g C m-2) > cropping land (256.8 g C m-2)2. The main factors influence soil respiration of agrosystems on the Loess Plateau(1) Positive correlation effects were found between soil respiration and soil temperature. The series of Q10 values were ranged:cropping land (1.95)> rangeland (1.77)> alfalfa pasture (1.58)> agroforestry (1.45)> silvo-pastoral (1.27).(2) Negative correlation effects were found between soil respiration and soil temperature in rangland, alfalfa pasture and agroforestry.(3) Aboveground biomass has positive correlation effects on soil respiration in all agrosystems besides AP3, CP, AP, SE and SP. All belowground biomass of the agrosystems has positie correlation effects on soil respiration.(4) Soil respiration showed strong spatial heterogeneity. The soil respiration in plant site was higher than that in between plant site significantly.(5) The main factors influencing soil respiration were different and that was SOC, belowground biomass, rainfall for rangeland, alfalfa pasture, agroforestry and silvo-pastoral.3. Storae changes of soil carbon, nitrogen, phosporus and water content during the succession of agrosystems(1) Soil organic carbon. The storage of SOC was decreased with the increases of soil depth and most of SOC was stored in top soil. The series of SOC were ranged : rangeland (547.5 Mg ha-1)> alfalfa pasture (491.7 Mg ha-1)> agroforestry (464.5 Mg ha-1)> silvo-pastoral (454.7 Mg ha-1)> cropping land (345.4 Mg ha-1)(2) Soil total nitrogen. The soil profile of 0-40 cm accounted for 49% of the soil total nitrogen in all the agrosystems and the series were ranged:rangeland (49.1 Mg ha-1)> alfalfa pasture (44.8 Mg ha-1)> agroforestry (39.5 Mg ha-1)> silvo-pastoral (36.4 Mg ha-1)> cropping land (29.1 Mg ha-1)(3) Soil total phosphorus. Most of soil phosphorus was sored in deep soil and the series were ranged:agroforestry (48.7 Mg ha-1)> rangeland (46.3 Mg ha-1)> alfalfa pasture(42.5 Mg ha-1)> silvo-pastoral(39.1 Mg ha-1)> cropping land(31.9 Mg ha-1).(4) Soil water content. The water content was decreased with the increases of soil depth and most of water was stored in top soil. Water consumption among the agrosystems was not significant but it was significant between different years for the same agrosystem.(5) Changes of soil C, N and P during the sucession of agrosystems. When rangeland was reclained as cropping land, SOC decreased 11%, TN decreased 27%, TP decreased 3.7%, annual soil CO2 emission decreased 22% and Q10 value increased 10%. When rangeland was reclained as forestry, SOC decreased 4.4 Mg ha-1, TN decreased 0.87 Mg ha-1, TP decreased 0.28 Mg ha-1, annual soil CO2 emission increased 249 g C m-2, Q10 decreased 28%. When cropping land was converted as alfalfa pasture, SOC increased 11.9% about 5.8 Mg ha-1, TN increased 0.95 Mg ha-1, TP increased 4.9%, annual soil CO2 emission increased 89%, Q10 decreased 19%. When cropping land were converted as silvo-pastoral, SOC increased 2.8 Mg ha-1. TN increased 0.29 Mg ha-1, TP increased 12.1%, annual soil CO2 emission increased 48% and Q10 value decreased 26%。

Mots clés : Soil respiration; Soil carbon emission; Agrosystems; Agricultural Land Use; Loess Plateau;

Présentation (CNKI)

Page publiée le 9 juin 2018