Tufts OpenCourseware
Authors: Kathleen Merrigan, Ph.D., William Lockeretz, Ph.D.


  • Roberts, R.K., and English, B.C. Economic evaluation of variable rate nitrogen application on cotton. 1999.
  • Christensen, L.A. Soil, Nutrient, and Water Management Systems Used in U.S. Corn Production. 2002.

Key Questions

Economic Evaluation of Variable Rate Nitrogen Application on Cotton

  • What is the key issue driving precision farming?
  • What are the advantages of variable rates of fertilizer application?
  • Does variable rates of fertilizer application promise better returns under all circumstances?

Soil, Nutrient and Water management Systems Used in US Corn Production

  • Why is corn cultivation an important issue to be looked into as one considers the effects of agriculture on the natural ecosystems in the US?
  • What is the most important factor a farmer would consider before substituting a current cultivation practice with a more environmentally friendly technique? What additional factors influence such a decision?
  • What factors influence nutrient management and adoption of irrigation technologies by corn growers?
  • What are the benefits of crop rotation?
  • What are the different kinds of crop rotation practices in corn cultivation? What is the most widely adopted crop rotation by corn growers?
  • What are the benefits of Crop Residue Management (CRM)?
  • Is there a link between fragile agricultural land and adoption of conservation tillage methods? What other factors affect this?
  • If one were to also consider the pattern of farm production diversity observed , would it be reasonable to say that those adopting conservation tillage practices are more environmentally conscious and sensitive than those not adopting?
  • What are the different approaches to setting yield goals, which in turn help in establishing the nutrient management regime?
  • How widespread is the use of chemical fertilizers and animal manures in corn cultivation?
  • Is there a correlation between nitrogen testing and nitrogen fertilizer application?
  • Is there a correlation between soil / tissue testing and the type of tillage system?
  • What are the pros and cons of installing sprinkler systems of irrigation in corn fields compared to other irrigation systems?
  • What is the dominant source of water for irrigation?
  • According to the author, how has the focus of technology for agriculture shifted over time?