Journal of Soils and Sediments

, Volume 10, Issue 2, pp 240–247 | Cite as

Spatial distribution of soil carbon in pastures with cow-calf operation: effects of slope aspect and slope position

SOILS, SEC 2 * GLOBAL CHANGE, ENVIRON RISK ASSESS, SUSTAINABLE LAND USE * RESEARCH ARTICLE

Abstract

Background, aim, and scope

The rate at which soil carbon (C) accumulates in terrestrial beef agro-ecosystem is uncertain, as are the mechanisms responsible for the current C sink. Broad knowledge of cattle movement in pasture situations is critical to understanding their impact on agro-ecosystems. Movement of free-ranging cattle varies due to spatial arrangement of forage resources within pastures and the proximity of water, mineral feeders, and shades to grazing sites. The effects of slope aspect (SA) and slope position (SP) on nutrient dynamics in pastures are not well understood. Few studies have been made of soil-vegetation and soil-landscape relationships along an elevation gradient in tropical and subtropical regions. Current literature suggests no clear general relationships between grazing management and nutrient cycling. Early study reported no effect of grazing on soils nutrients, while other studies determined increases in soil nutrients due to grazing. We hypothesize that SA and SP could be of relative importance in controlling spatial variability of soil organic carbon (SOC). This study addressed the effects of SA and SP on the spatial distribution of SOC in forage-based pastures with cow-calf operation in subtropical region of southeastern USA.

Materials and methods

Soil samples were collected at 0–20 and 20–40 cm on contiguous south-, north-, east-, and west-facing slopes across different landscape positions (top slope, middle slope, and bottom slope) of 100 ha pastures during three summer seasons (2004–2006). Soil samples were air-dried, passed through a 2-mm mesh sieve, and visible roots were removed prior to analyses of SOC and other soil properties likely to affect spatial distribution of SOC. Analyses of soils were conducted at the Subtropical Agricultural Research Station in Brooksville, FL, following the dry-ash or the ‘loss-on-ignition’ method. Concentrations of organic carbon in soils from four different SA, three SP, and two soil depths (SD) in 2004, 2005, and 2006 were analyzed statistically following a four-way analysis of variance using the SAS PROC general linear model.

Results

There was an SA × SP interaction (p ≤ 0.0001) effect on the concentration of SOC. The two highest concentrations of SOC were observed from top slope (8.4 g kg−1) and middle slope (7.8 g kg−1) in south-facing slope, and the two lowest levels of SOC were in top slope (2.6 g kg−1) and middle slope (3.0 g kg−1) of north-facing slope, respectively. Soil C also varied significantly among SA (p ≤ 0.0001), SP (p ≤ 0.001), and SD (p ≤ 0.0001). Averaged across years and SP, soils on the south-facing slope contained the greatest amount of SOC, while soils on the north-facing slope had the least amount of SOC. Average concentrations of SOC in top slope and middle slope were comparable. These values were significantly (p ≤ 0.05) higher when compared with soils from bottom slope. About 73% of SOC spatial variability could be explained by total clay content. Concentrations of SOC were quadratically (SOC = 0.05 × clay2 − 0.29 × clay + 4.4; p ≤ 0.001) related with total clay content. No other significant correlations between SOC and other soil properties were found.

Discussion

Our results have shown that soils on the south-facing slope had greatest concentration of SOC, while soils on the north-facing slope had the lowest concentration of SOC. The differences may be attributed to topographic aspect-induced microclimatic differences, which are causing differences in the biotic soil component and SOC trend. SA may be acting as an important topographic factor influencing local site microclimate mainly because it determines the amount of solar radiation received. Differences in microclimate are often linked to varying soil moisture and erosion potential and in turn could be used to explain distribution of plant communities. The north-facing slope had the lower forage availability when compared with the south-facing slope. There was a decreasing trend in the average forage availability with decreasing slope. Between the top slope and the bottom slope, forage availability declined from 2,484 to 1,448 kg ha−1, which can be attributed to more grazing activities of cattle at bottom slope. Differences in SOC among different SA and SP could also be explained by varying amount of total clay. Concentrations of SOC were linearly related with increasing total clay content. The greatest amount of SOC was observed from soils located at the top slope of south-facing slope. Of the entire SA, south-facing slope had the greatest concentration of total clay, while the greatest clay content among SP was observed from the top slope. Results further revealed that 73% of SOC spatial variability could be explained by total clay content. The relationship between SOC and total clay content was best described by a quadratic equation: SOC = 0.05 × clay2 − 0.29 × clay + 4.4; R2 = 0.73; p ≤ 0.001.

Conclusions

Results of our study are suggesting that SA and SP could be of relative importance in controlling spatial variability of SOC. Averaged across years, soils on the south-facing slope contained the greatest amount of SOC, while soils on the north-facing slope had the least amount of SOC. Based on the average concentration of SOC, the south-facing slope may have sequestered about 6,460 kg ha−1 of SOC.

Recommendation and perspectives

Results have shown that landscape attributes (e.g., SA and SP) associated with beef cattle pastures as a part of the agro-ecological system could be potential sink for C sequestration, thus reducing atmospheric carbon dioxide concentrations. It is still critical to understand how the interactions of pasture management and landscape are affecting soil C dynamics. More studies are needed to assess the rate at which soil C is accumulating as well as the mechanisms responsible for the current and future C sink in forage-based pastures with cow-calf operations.

Keywords

Bahiagrass Cow-calf Soil carbon Slope aspects Slope positions Subtropics 

References

  1. Bouyocous GJ (1962) Hydrometer method improved for making particle-size analyses of soils. Agron J 54:464–465Google Scholar
  2. Briske DD, Richards JH (1995) Plant responses to defoliation: a physiological, morphological and demographic evaluation. In: Bedunah DJ, Sosebee RE (eds) Wildland plants: physiological ecology and developmental morphology. Society of Range Management, Denver, pp 635–710Google Scholar
  3. Cluzeau D, Binet F, Vertes F, Simon JC, Riviere JM, Trehen P (1992) Effects of intensive cattle trampling on soil-plant-earthworms system in two grassland types. Soil Biol Biochem 24(12):1661–1992CrossRefGoogle Scholar
  4. Coble DW, Milner KS, Marshal JD (2001) Above- and below-ground production of trees and other vegetation on contrasting aspects in western Montana. For Ecol Manag 42:231–241CrossRefGoogle Scholar
  5. Derner JD, Beriske DD, Boutton TW (1997) Does grazing mediate soil carbon and nitrogen accumulation beneath C4, perennial grasses along an environmental gradient? Plant Soil 191:147–156CrossRefGoogle Scholar
  6. Dormaar JF, Johnston A, Smoliak S (1997) Seasonal variations in chemical characteristics of soil organic matter of grazed and ungrazed mixed prairie and fescue grassland. J Range Manage 30:195–198CrossRefGoogle Scholar
  7. Gallardo JF, Saavedra J (1987) Soil organic matter determination. Commun Soil Sci Plant Anal 18:699–707CrossRefGoogle Scholar
  8. Ganskopp D (2001) Manipulating cattle distribution with salt and water in large arid-land pastures: a GPS/GIS assessment. Appl Anim Behav Sci 73:251–262CrossRefGoogle Scholar
  9. Grieve IC, Proctor J, Cousins SA (1990) Soil variation with altitude on Volcan Barba Costa Rica. Catena 17:525–534CrossRefGoogle Scholar
  10. Holland EA, Detling JK (1990) Plant response to herbivory and belowground nitrogen cycling. Ecology 71:1040–1049CrossRefGoogle Scholar
  11. Holland PG, Steyn DG (1975) Vegetational responses to latitudinal variations in slope angle and aspect. J Biogeogr 2:179–183CrossRefGoogle Scholar
  12. Hyde AG, Law L Jr, Weatherspoon RL, Cheney MD, Eckenrode JJ (1977) Soil survey of Hernando County, FL. USDA-NRCS, Washington, DC and University of Florida, Gainesville, FL, p 152Google Scholar
  13. Lowther JR, Smethurst PJ, Carlye JC, Mabiar EK (1990) Methods for determining organic carbon in Podzolic sands. Commun Soil Sci Plant Anal 21:457–470CrossRefGoogle Scholar
  14. Manley JT, Schuman GE, Reeder JD, Hart RH (1995) Rangeland soil carbon and nitrogen responses to grazing. J Soil Water Conserv 50:294–298Google Scholar
  15. Marrs RH, Proctor J, Heaney A, Mountford MD (1988) Changes in soils, nitrogen mineralization and nitrification along an altitudinal transect in tropical rain forest in Costa Rica. J Ecol 76:466–482CrossRefGoogle Scholar
  16. Martin SC, Ward DE (1973) Salt and meal-salt help distribute cattle use on semi-desert range. J Range Manage 26:94–97CrossRefGoogle Scholar
  17. Mathews BW, Tritschler JP, Carpenter JR, Sollenberger LE (1999) Soil macronutrients distribution in rotationally stocked kikuyugrass paddocks with short and long grazing periods. Commun Soil Sci Plant Anal 30:557–571CrossRefGoogle Scholar
  18. Milchunas DG, Lauenroth WK (1993) Quantitative effects of grazing on vegetation and soils over a global range of environments. Ecol Monogr 63:327–366CrossRefGoogle Scholar
  19. Parton WJ, Schimel DS, Cole CV, Ojima DS (1987) Analysis of factors controlling soil organic matter levels in Great Plains grasslands. Soil Sci Soc Am J 51:1173–1179Google Scholar
  20. SAS Institute (2000) SAS/STAT User’s Guide. Release 6.03. SAS Institute, Cary, North Carolina, p 494Google Scholar
  21. Schulte EE, Kaufman C, Peter JB (1991) The influence of sample size and heating time on soil weight loss-on-ignition. Commun Soil Sci Plant Anal 22:159–168CrossRefGoogle Scholar
  22. Schuman GE, Burwell RE, Piest RF, Spomer RG (1973) Nitrogen losses in surface runoff from agricultural watersheds in Missouri Valley losses. J Environ Qual 2:299–302Google Scholar
  23. Schuman GE, Reeder JD, Manley JT, Hart RH, Manley WA (1999) Impact of grazing management on the carbon and nitrogen balance of mixed-grass rangeland. Ecol Appl 91:65–71CrossRefGoogle Scholar
  24. Schuster JL (1964) Root development of native plants under three grazing intensities. Ecology 45:63–70CrossRefGoogle Scholar
  25. Senft RL, Rittenhouse LR, Woodmansee RG (1983) The use of regression models to predict spatial patterns of cattle behavior. J Range Manage 36(5):553–557CrossRefGoogle Scholar
  26. Senft RL, Rittenhouse LR, Woodmansee RG (1985) Factors influencing selection of resting sites by cattle on shortgrass steppe. J Range Manage 38:295–299CrossRefGoogle Scholar
  27. Senft RL, Coughenour MB, Bailey DW, Rittenhouse LR, Sala OE, Swift DM (1987) Large herbivore foraging and ecological hierarchies. Bioscience 37:789–799CrossRefGoogle Scholar
  28. Sigua GC, Coleman SW (2007) Sustainable management of nutrients in forage-based pasture soils: effect of animal congregation sites. J Soils Sediments 6(4):249–253CrossRefGoogle Scholar
  29. Trimble SW, Mendel AC (1995) The cow as a geomorphic agent—a critical review. Geomorphology 13:233–253CrossRefGoogle Scholar
  30. Tsui CC, Chen ZS, Hsieh CF (2004) Relationships between soil properties and slope position in a lowland rain forest of southern Taiwan. Geoderma 123:131–142CrossRefGoogle Scholar
  31. Weinhold BJ, Hendrickson JR, Karn JF (2001) Pasture management influences on soil properties in the Northern Great Plains. J Soil Water Conserv 56:27–31Google Scholar
  32. White SL, Sheffield RE, Washburn SP, King LD, Green JT Jr (2001) Spatial and time distribution of dairy cattle excreta in an intensive pasture systems. J Environ Qual 30:2180–2187CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  1. 1.United States Department of AgricultureAgricultural Research Service, Subtropical Agricultural Research StationBrooksvilleUSA

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