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This article in SSSAJ

  1. Vol. 68 No. 5, p. 1695-1704
    Received: Jan 6, 2004

    * Corresponding author(s): k-bronson@tamu.edu
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Carbon and Nitrogen Pools of Southern High Plains Cropland and Grassland Soils

  1. Kevin F. Bronson *a,
  2. Ted M. Zobeckb,
  3. Teresita T. Chuaa,
  4. Veronica Acosta-Martinezb,
  5. R. Scott van Peltc and
  6. J. D. Bookera
  1. a Texas A&M Univ., Texas Agric. Exp. Stn., RR 3 Box 219, Lubbock, TX 79403
    b Cropping Systems Research Laboratory, 3810 4th St., Lubbock, TX 79415
    c Cropping Systems Research Laboratory, 30 W West I20, Big Spring, TX 79720


Soil C and N have long been recognized as important indicators of soil productivity. The current low levels of soil C and N of cropland soils have led to interest in sequestering C with reduced tillage cropping systems and the Conservation Reserve Program (CRP). Our objective was to assess agroecosystem effects on soil C and N pools in the Southern High Plains. The agroecosystems included three cotton (Gossypium hirsutum L.) cropping systems, CRP land, and native rangeland (NR). We sampled 0- to 5-, 5- to 10-, 10- to 15-, and 15- to 30-cm soil depths at 12 farm sites in five counties in West Texas. Total soil C and N, particulate organic matter (POM) C and N, natural abundance of carbon-13 isotope (δ13C) of POM and of whole soil, potentially mineralizable C and N, water-extractable carbon (WEC), and extractable ammonium (NH+ 4) and nitrate (NO 3) were determined. Total C and N in the 0- to 30-cm soil profile were 34 Mg C ha−1 and 2.5 Mg N ha−1 for NR, and 23 Mg C ha−1 and 1.9 Mg N ha−1 for cropland systems, respectively. Total soil C and N in CRP land were greater in cropland soils only in the 0- to 5-cm layer, and were 24 Mg C ha−1 and 2.1 Mg N ha−1 in 0 to 30 cm. Labile C and N pools were positively correlated with each other and with total soil C and N. Low soil test P may have limited C and N sequestration in CRP land and NR. Improved management practices are needed to sequester C and N in CRP and conservation-tillage cotton systems in the Southern High Plains.

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