1. 01 មករា 2017 Includes cover crop facts on how to keep nutrients out of waterways.
  2. 01 មករា 1979 Cornell International Agriculture Bulletin 36 Field expereiments were performed in Puerto Rico, Brazil, and Ghana on highly weathered acid soils (Oxisols and Ultisols) to assess the capacity of these soils to supply nitrogen to nonleguminous crops and to determine crop response to fertilizer...
  3. 01 មករា 1988 These are proceedings from a symposium specifcally addressing the impact of water and nitrogen on crop production. 217 pages, charts