- Authors:
- Source: Global Change Biology
- Volume: 8
- Issue: 4
- Year: 2002
- Summary: The effects of land use change on soil carbon stocks are of concern in the context of international policy agendas on greenhouse gas emissions mitigation. This paper reviews the literature for the influence of land use changes on soil C stocks and reports the results of a meta analysis of these data from 74 publications. The meta analysis indicates that soil C stocks decline after land use changes from pasture to plantation (-10%), native forest to plantation (-13%), native forest to crop (-42%), and pasture to crop (-59%). Soil C stocks increase after land use changes from native forest to pasture (+8%), crop to pasture (+19%), crop to plantation (+18%), and crop to secondary forest (+53%). Wherever one of the land use changes decreased soil C, the reverse process usually increased soil carbon and vice versa. As the quantity of available data is not large and the methodologies used are diverse, the conclusions drawn must be regarded as working hypotheses from which to design future targeted investigations that broaden the database. Within some land use changes there were, however, sufficient examples to explore the role of other factors contributing to the above conclusions. One outcome of the meta analysis, especially worthy of further investigation in the context of carbon sink strategies for greenhouse gas mitigation, is that broadleaf tree plantations placed onto prior native forest or pastures did not affect soil C stocks whereas pine plantations reduced soil C stocks by 12-15%.
- Authors:
- Paustian, K.
- Conant, R. T.
- Source: Global Biogeochemical Cycles
- Volume: 16
- Issue: 4
- Year: 2002
- Summary: Excessive grazing pressure is detrimental to plant productivity and may lead to declines in soil organic matter. Soil organic matter is an important source of plant nutrients and can enhance soil aggregation, limit soil erosion, and can also increase cation exchange and water holding capacities, and is, therefore, a key regulator of grassland ecosystem processes. Changes in grassland management which reverse the process of declining productivity can potentially lead to increased soil C. Thus, rehabilitation of areas degraded by overgrazing can potentially sequester atmospheric C. We compiled data from the literature to evaluate the influence of grazing intensity on soil C. Based on data contained within these studies, we ascertained a positive linear relationship between potential C sequestration and mean annual precipitation which we extrapolated to estimate global C sequestration potential with rehabilitation of overgrazed grassland. The GLASOD and IGBP DISCover data sets were integrated to generate a map of overgrazed grassland area for each of four severity classes on each continent. Our regression model predicted losses of soil C with decreased grazing intensity in drier areas (precipitation less than 333 mm yr−1), but substantial sequestration in wetter areas. Most (93%) C sequestration potential occurred in areas with MAP less than 1800 mm. Universal rehabilitation of overgrazed grasslands can sequester approximately 45 Tg C yr−1, most of which can be achieved simply by cessation of overgrazing and implementation of moderate grazing intensity. Institutional level investments by governments may be required to sequester additional C.
- Authors:
- Grove, J. H.
- Diaz-Zorita, M.
- Source: Soil & Tillage Research
- Volume: 65
- Issue: 1
- Year: 2002
- Summary: The western part of the Argentine Pampas is a subhumid and semiarid region consisting of extensive plain with deep sandy and sandy-loam soils. The agricultural system includes pastures in rotation with annual grain crops and grazed crops or continuous annual row cropping. The objective of this review was to present and discuss changes in soil properties due to different soil management systems, mainly no-tillage practices, in the western part of the Argentine Pampas. The effects of tillage, crop sequences under no-till, and grazing on soil properties and crop productivity have been studied since 1990 on loamy and sandy Haplic Phaeozem (Typic Hapludolls and Entic Hapludolls) and Haplic Kastanozem (Typic Haplustolls). A database developed from the yield and soil test records of growers affiliated with Regional Consortium for Agricultural Experimentation (CREA) were also utilized in the study. The results showed that soil organic C (SOC) content depends both on soil texture and soil management. SOC decreases when the length of the row crop cycle increases and also in moldboard plow and chisel-tillage systems. Pastures and no-till row crop sequences with more years of maize (Zea mays L.) and wheat (Triticum aestivum L.), than sunflower (Helianthus annus L.) or soybean (Glycine max (L.) Merrill) tended to increase the SOC content in the 0-20 cm layer. Deep tillage of no-till soils with compacted layers improved maize dry matter production but, in the same experiment, yield was increased more by nitrogen fertilization than by subsoil tillage. The grazing of crop residues increases the soil bulk density only in the 0-5 cm layer of tilled soils, but did not significantly change bulk density on soils under continuous no-till. Crop productivity was related to SOC content of the 0-20 cm layer of the soils. Due to the positive effect of SOC on crop yields, no-till soil management and pasture-annual row crop rotations are two practices that permit the development of sustainable production systems in the western part of the Argentine Pampas.
- Authors:
- Owensby, C. E.
- Rice, C. W.
- Source: The Potential of U.S. Grazing Lands to Sequester Carbon and Mitigate the Greenhouse Effect
- Year: 2001
- Authors:
- Stuedemann, J. A.
- Franzluebbers,A. J.
- Sanderson, M. A.
- Stout, W. L.
- Schnabel, R. R.
- Source: The Potential of U.S. Grazing Lands to Sequester Carbon and Mitigate the Greenhouse Effect
- Year: 2001
- Authors:
- Janzen, H. H.
- Herrick, J. E.
- Schuman, G. E.
- Source: Carbon Sequestration Potential of U.S. Grazing Lands
- Year: 2001
- Summary: Carbon dynamics of rangeland soils are very complex and only limited detailed research has been conducted to assess the role of management and grazing strategies on soil C changes and the potential for enhanced C sequestration. Soil erosion also can impact the soil C pools in rangeland ecosystems, but much of the erosion does not result in loss of C from the landscape but rather a repositioning on the landscape. In an attempt to estimate the effects of management on the C storage potential of the rangeland ecosystems, we have reviewed the literature on the subject and made some assumptions in order to make some qualitative estimates of C sequestration potential and potential avoided losses of C through management. We believe about 19 Tg C yr-1 can be sequestered through management on lands that are in need of improved management and through soil C regeneration in CRP lands. However, we estimate that 44 Tg C yr-1 can be maintained through ensured good management and by preventing CRP lands from being brought back into crop production. The estimated 63 Tg C yr-1 that can be sequestered and/or prevented from being lost from well- managed rangelands and through maintenance of CRP lands may be small in comparison to the estimates of C sequestration by improved production practices on croplands in the U.S.; however, this level of C storage in a natural ecosystem tends to be more stable and less prone to major C losses through erosional losses and shifts in management.
- Authors:
- Mendenhall, A. G.
- Franks, C. D.
- Stone, J.
- Moffitt, D. L.
- Sobecki, T. M.
- Source: The Potential of U.S. Grazing Lands to Sequester Carbon and Mitigate the Greenhouse Effect
- Year: 2001
- Summary: Broadly scaled information about the extent and character of U.S. grazing lands provides a context for considering the more finely scaled processes driving carbon (C) cycling on grazing lands.
- Authors:
- Lal, R.
- Follett, R. F.
- Kimble, J. M.
- Source: The Potential of U.S. Grazing Lands to Sequester Carbon and Mitigate the Greenhouse Effect
- Year: 2001
- Authors:
- Source: The Potential of U.S. Grazing Lands to Sequester Carbon and Mitigate the Greenhouse Effect
- Year: 2001
- Authors:
- Source: The Potential of U.S. Grazing Lands to Sequester Carbon and Mitigate the Greenhouse Effect
- Year: 2001
- Summary: This book chapter examines the organic carbon pools in grazing land soils.
