Total and organic soil carbon in cropping systems of Nepal
- 211 Downloads
The significance of soil organic matter (SOM) in sustaining agriculture has long been recognized. The rate of change depends on climate, cropping system, cropping practice, and soil moisture. A 3-yr on-farm study was conducted in two major agro-ecologies (hills with warm-temperate climate and plains with subtropical climate) of Nepal. The soils in warm-temperate climate are Lithic subgroups of Ustorthents with well-drained loamy texture, and in subtropical climate are Haplaquepts with imperfectly drained loamy texture. Farmers’ predominant cropping systems were selected from different cultivation length in addition to a reference sample collected from adjacent virgin forest. The objectives were to examine the effect of cultivation length and cropping system on total carbon, KMnO4-oxidizable soil C, C storage, and C/N ratio in two climatic scenarios: warm-temperate and subtropical. A large difference in KMnO4-oxidizable soil organic C was observed due to the effect of cultivation length and cropping system. However, TC remained similar during the 3-year study. The decrease in KMnO4-oxidizable C due to cultivation was more in the surface layer (43–56%) than in the subsurface layer (20–30%). Total C in uncultivated, < 10-year cultivated, and > 50-year cultivated soil was 22, 13, and 10 g kg−1 in warm-temperate climate and 10, 6, and 5 g kg−1 in subtropical climate, respectively. During the 3-year study period in both climates, large changes in soil C were observed for KMnO4-oxidizable C but not for TC, confirming our earlier work on the usefulness of the KMnO4 oxidized fraction for detecting a relatively short-term increase or decrease in soil C pool. The TC storage in uncultivated, < 10-year cultivated, and > 50-year cultivated soil was 38, 25, and 19 Mg ha−1 in warm-temperate climate and 22, 15, and 12 Mg ha−1 in subtropical climate, respectively. The rice–wheat and maize–potato cropping systems were good in storing soil C of 30 and 20 Mg ha−1 for 0–15-cm soil depth in warm-temperate climate. The rice–wheat cropping system was also good in storing soil C in subtropical climate (19 Mg ha−1) compared with other cropping systems studied.
KeywordsKMnO4-oxidizable carbon Total carbon Carbon storage C/N ratio Climate Cropping system
Unable to display preview. Download preview PDF.
This study was funded by the Rice–Wheat Consortium for the Indo-Gangetic Plain. The authors would like to thank S.L. Maskey, chief soil scientist, Soil Science Division, Nepal Agricultural Research Council, Lalitpur, Nepal; P. Hobbs, Cornell University, USA; and R.K. Gupta, Rice-Wheat coordinator, New Delhi, India, for their suggestions.
- IRRI (International Rice Research Insitute). (1998) IRRISTAT for Windows [Online]. Version 4.0. International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines http://www.cgiar.org/irri/irristat.htm
- Ladha JK, Dawe D, Pathak H, Padre AT, Yadav RL, Singh B, Singh Y, Singh P, Kundu AL, Sakal R, Ram N, Regmi AP, Gami SK, Bhandari AL, Amin R, Yadav CR, Bhattarai EM, Das S, Aggrawal HP, Gupta RK, Hobbs PR (2003) How extensive are yield declines in long-term rice-wheat experiments in Asia? Field Crops Res 81:159–180CrossRefGoogle Scholar
- Lal R, Kimble J, Follett R (1998) Knowledge gaps and research priorities. In: Lal R et al (eds) Soil processes and the carbon cycle. Adv. Soil Sci. CRC Press, Boca Raton FL, pp 595–604Google Scholar
- Maskey SL, Shrestha RK, Shrestha B, Tripathi BP, Bhattarai EM, Munankarmy RC, Khadka YG (2002) Strategies for soil fertility research in the hills of Nepal. Soil Science Division, Nepal Agric. Research Council, Nepal/Hill Agriculture Research Project, DFID, NepalGoogle Scholar
- MOA (Ministry of Agriculture) (1999) Statistical Information on Nepalese Agriculture – 1998/99. Ministry of Agriculture, Agricultural Statistics Division, NepalGoogle Scholar
- Paul EA, Morris SJ, Bohm S (2001) The determination of soil C pool sizes and turnover rates: biophysical fractionation and tracers. In: Lal R et al. (eds) Assessment methods for soil carbon. CRC Press, Boca Raton, Florida, USA, pp 193–206Google Scholar
- PCARRD (Philippine Council for Agriculture, Forestry and Natural Resources Research and Development). (1980) Standard methods of analysis for soil, plant tissue, water and fertilizer. Farm Resources and Systems Research Division, Philippine council for Agriculture and Research, Los Baños, Laguna, PhilippinesGoogle Scholar
- Schlesinger WH (1986) Changes in soil carbon storage and associated properties with disturbance and recovery. In: Trabalka JR and Reichle DE (eds) The change in pedogenic carbonates. Lewis Publishers, Boca Raton, FL, pp 194–220Google Scholar
- Selvaraju R (1994) Pre-season fallow management and current-season land configuration techniques on rabi intercropping systems of rainfed Vertisoil. Ph.D. thesis submitted to Tamil Nadu Agric. Univ., Coimbatore, IndiaGoogle Scholar
- Shrestha S (1992) Crisis area study. Mountain Farming System, International Center for Integrated Mountain Development, Nepal. Discussion Paper No. 32Google Scholar
- Soulides DA, Allison FE (1961) Effect of drying and freezing soil on CO2 production, available mineral nutrients, aggregation and bacterial population. Soil Sci 91:291–298Google Scholar
- Uren N (1991) The management of soil organic matter for sustainable agriculture. Agric-Sci 4:45–48Google Scholar
- Zhu Z, Liu C, Jiang B (1984) Mineralization of organic nitrogen, phosphorus, and sulfer in some paddy soils of China. In: Organic matter and rice. International Rice Research Institute, Los Baños (Philippines), pp 259–272Google Scholar