1. Allen SE (1989) Analysis of vegetation and other organic materials. In: SE Allen (ed) Chemical analysis of ecological materials, 2nd edn. Blackwell, Britain, pp 46–61
2. Beijing Agricultural University (1994) Agricultural chemistry (pandect) (in Chinese). Agricultural Press, Beijing
3. Bremner JM, Mulvaney CS (1982) Nitrogen-total. In: Page AL, Mille RH, Keeney DR (eds) Methods of soil analysis, part 2. Agronomy, vol 9, 2nd edn. Soil Sci Soc Am, Madison, WI, pp 595–624
4. Cadisch GR, Schunke M, Giller KZ (1994) Nitrogen cycle in monoculture grassland and legume-grass mixture in Brazil red soil. Trop Grasslands 28:43–52
5. Chen H, Kang Y, Feng J (1991) Preliminary study on the plant growth and water balance in Shapotou area, Tengger Desert (in Chinese). J Desert Res 11:1–10