Soil organic carbon distribution in relation to land use and its storage in a small watershed of the Loess Plateau, China

doi:10.1016/j.catena.2011.07.012

CATENA

Volume 88, Issue 1, January 2012, Pages 6-13

https://doi.org/10.1016/j.catena.2011.07.012 Get rights and content

Abstract

Soil organic carbon (SOC) is an important component in agricultural soil, and its stock is a major part of global carbon stocks. Estimating the SOC distribution and storage is important for improving soil quality and SOC sequestration. This study evaluated the SOC distribution different land uses and estimated the SOC storage by classifying the study area by land use in a small watershed on the Loess Plateau. The results showed that the SOC content and density were affected by land use. The SOC content for shrubland and natural grassland was significantly higher than for other land uses, and cropland had the lowest SOC content. The effect of land use on the SOC content was more significant in the 0–10 cm soil layer than in other soil layers. For every type of land use, the SOC content decreased with soil depth. The highest SOC density (0–60 cm) in the study area was found in shrublandII (Hippophae rhamnoides), and the other land uses decreased in the SOC density as follows: natural grassland > shrublandI (Caragana korshinskii) > abandoned cropland > orchard > level ground cropland > terrace cropland > artificial grassland. Shrubland and natural grassland were the most efficient types for SOC sequestration, followed by abandoned cropland. The SOC stock (0–60 cm) in this study was 23,584.77 t with a mean SOC density of 4.64 (0–60 cm).

Highlights

► Estimating SOC distribution and storage is important for improving soil quality and SOC sequestration. ► SOC distribution and storage for different land uses were evaluated in a small watershed. ► Shrubland and natural grassland were the most efficient land use types for SOC sequestration. ► The SOC stock (0–60 cm) was 23,584.77 t with a mean SOC density of 4.64 (0–60 cm).

Introduction

Soil organic carbon (SOC), an important component in agricultural soil, is a key indicator for assessing soil quality (Gregorich et al., 1994) and plays an important role in increasing crop productivity (Stevenson and Cole, 1999). The SOC stock, as a significant part of the global carbon stocks, contains about two times the amount of carbon storage in the atmosphere and vegetation (IPCC, 2000). The SOC stock is also an important part of the missing atmospheric carbon sink (Schimel et al., 2001). Therefore, understanding the SOC distribution and stock is essential in achieving food security (Lal, 2004) and alleviating carbon emissions resulting in global warming (Su et al., 2006).

Scholars have performed a lot of studies on the SOC distribution and stock on global (Bohn, 1982, Bolin, 1970), country (Arrouays et al., 2001, Krogh et al., 2003) and regional (Sun et al., 2004, Wang et al., 2004) scales. However, these studies had a high degree of uncertainty due to the lack of complete inventory data, the different data sources, and the inherent and spatial variability of SOC (Xie, et al., 2004). The SOC was affected by many factors, including climate, hydrology, soil, land use, and others. Establishing a detailed database of a given region that includes the above factors was necessary. Of these factors, land use was the most sensitive to human disturbance. Therefore, monitoring the SOC for different land uses is essential for estimating the SOC distribution and stock.

The Loess Plateau is one of the regions with the most severe soil erosion in the world, and it is also a major agricultural production region in China (Fu et al., 2002, Hessel et al., 2003, Ritsema, 2003). Long-term, poor land use management that resulted in vegetation destruction, such as deforestation, overgrazing and over-reclamation, has accelerated soil erosion (Fu et al., 2009) and accordingly deteriorated the ecological environment (Zheng, 2006). Meanwhile, the SOC on the Loess Plateau has decreased and is lower than the average level in China (Yu et al., 2007). Consequently, the Grain for Green project was implemented in 1999 by the Chinese Government to control soil erosion and restore the ecological environment (Fu et al., 2002). Over the past decade, the land use and vegetation on Loess Plateau has changed significantly, converting slope cropland to other land uses, such as artificial grassland, shrubland, or abandoned cropland. Studying the SOC in relation to different land uses and different vegetation types for ecological rehabilitation was crucial for improving SOC sequestration and soil quality.

This paper examined the SOC distribution and stock at a small watershed in the Loess Plateau. The objectives of this study were: 1) to analyze the effect of land use on the SOC content and soil bulk density; 2) to analyze the effect of land use on the SOC density in the small watershed; 3) to estimate the SOC spatial distribution and stock in a small watershed; and 4) to discuss which land use management is most favorable for SOC sequestration and the sustainable agriculture development.

Section snippets

Study area

The study area was the Sidigou watershed (106°24′47″–106°26′17″E, 35°57′24″–35°59′28″N), which is located at the town of Hechuan in the southern Ningxia Province of northwest China, and covers an area of 5.16 km² (Fig. 1). This small watershed is in the “hill and gully” region of the western Loess Plateau, with an altitude ranging from 1590 to 1815 m above sea level. Seventy percent of the region is covered by hills, 18% is covered by valleys and lakes and 12% is flat land (slope < 5°), and it has

Descriptive statistics for the SOC

The distribution range of the SOC content, soil bulk density and the SOC density are shown in Table 1. The SOC content and density varied significantly. The 50% SOC content in the three soil layers (0–10 cm, 10–30 cm, and 30–60 cm) and the SOC density ranged between 6.95–10.86, 4.77–8.88, 3.59–7.03, and 3.39–5.90, respectively. The soil bulk density displayed little variation. The distribution character can also be determined from a discriminating parameter, CV. A CV of < 0.1 indicates low

Effects of land use on SOC content

It is usually assumed that land use can affect the SOC content. Soil organic carbon was increased when cropland converted into land uses with perennial vegetation (Groenendijk et al., 2002). In contrast, soil can lose its organic carbon into the atmosphere because of an increase in decomposition and erosion when vegetation is destructed by converting perennial vegetation into cultivated land, which then leads to increased atmospheric CO₂ (Houghton, 1991).

In this study, the SOC content of

Conclusion

Land use has a significant effect on the SOC content in the study area. The SOC content under shrubland and natural grassland was significantly higher than that under other land uses. Cropland had a lowest SOC content of all the land uses. Furthermore, land use also affected the soil bulk density. The soil bulk density under shrubland was significantly lower than that for any other land uses. However, the difference of soil BD among land uses was found to be smaller than that of the SOC

Acknowledgements

This study was sponsored by the National Natural Sciences Foundation of China (41030532, 40971171), the national key projects of 11th five year plan by MOST (2006BCA01A07), the West Light Foundation of The Chinese Academy of Science and the Foundation for Youths Teacher by Northwest A&F University. In addition, we are grateful to Professor Pardo-Iguzquiza, Eulogio for providing MLREML program.

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Soil organic carbon distribution in relation to land use and its storage in a small watershed of the Loess Plateau, China

Abstract

Highlights

Introduction

Section snippets

Study area

Descriptive statistics for the SOC

Effects of land use on SOC content

Conclusion

Acknowledgements

Remote Sensing of Environment

Geoderma

Geoderma

Catena

Geoderma, Pedometrics

Agricultural Ecosystem and Environment

Geoderma

Computers and Geosciences

Catena

Pedosphere

Geoderma

Pedosphere

Pedosphere

Pedosphere

Soil organic carbon density and land restoration: example of southern mountain area of Ningxia Province, Northwest China

Communications in Soil Science and Plant Analysis

The carbon content of topsoil and its geographical distribution in France

Soil Use Manage

Estimate of organic carbon in world soils

Soil Science Society of American Journal

The carbon cycle

Scientic American

Effect of land use conversion on soil organic carbon sequestration in the loess hilly area, loess plateau of China

Ecological Research

Vertical distribution of representative plantation's fine root in wind-water erosion crisscross region, Shenmu

Acta Botany Boreal-Occident Sinica