References
- Attoe, O. J. 1947. Potassium fixation and release in soils occurring under moist and dry conditions. Soil Science Society of America Proceedings 11: 145–149.
- Barbagelata, P. A., and A. P. Mallarino. 2012. Field correlation of potassium soil test methods based on dried and field-moist soil samples for corn and soybean. Soil Science Society of America Journal 77: 630–642.
- Blake, G. R., and K. H. Hartge. 1986. Bulk density. In: Methods of Soil Analysis. Part 1, ed. A. Klute, pp. 363–367. Madison, WI: ASA and SSSA.
- Burns, A. F., and S. A. Barber. 1961. The effect of temperature and moisture on exchangeable potassium. Soil Science Society of America Proceedings 23: 349–352.
- Clemson University. 2013. Dry ash procedure for P, K, Ca, Mg, Zn, Cu, Fe. Available at: http://www.clemson.edu/public/regulatory/ag_svc_lab/plant_tissue/plant_tissue_feed_forage_analysis_procedure5.html (accessed 4 February 2014).
- Clover, M. W., and A. P. Mallarino. 2013. Corn and soybean tissue potassium content response to potassium fertilization and relationships with grain yield. Soil Science Society of America Journal 77: 630–642.
- Combs, S. M., and M. V. Nathan. 1998. Soil organic matter. In: Recommended Chemical Soil Test Procedures for the North Central Region, pp. 53–58. Columbia, MO: Missouri Agricultural Experiment Station SB 1001.
- Ebelhar, S. A., and E. C. Varsa. 2000. Tillage and potassium placement effects on potassium utilization by corn and soybean. Communications in Soil Science and Plant Analysis 31: 2367–2377.
- Elliott, E. T., J. W. Heil, E. F. Kelly, and H. C. Monger. 1999. Soil structural and other physical properties. In: Standard Soil Methods for Long term Ecological Research, ed. G. P. Robertson, pp. 74–88. New York: Oxford University Press.
- Erich, M. S., and B. R. Hoskins. 2011. Effect of soil drying on soil pH and nutrient extractability. Communications in Soil Science and Plant Analysis 42: 1167–1176.
- Fixen, P. E., T. W. Bruulsema, T. L. Jensen, R. Mikkelsen, T. S. Murrell, S. B. Phillips, Q. Rund, and W. M. Stewart. 2010. Fertility of North American soils – Summary 2010. Better Crops with Plant Foods 94(4): 6–8.
- Franzen, D. W. 2010. SF-882 (Revised) North Dakota Fertilizer recommendation Tables and Equations. Fargo, ND: NDSU Extension service.
- Franzen, D. W. 2011. Variability of soil test potassium in space and time. In: North Central Extension–Industry Soil Fertility Conference, Des Moines, IA. 16–17 Nov. 2011, pp. 74–82. Brookings, SD: Int. Plant Nutrition Inst.
- Haby, V. A., J. R. Sims, E. O. Skogley, and R. E. Lund. 1988. Effect of sample pretreatment on extractable soil potassium. Communications in Soil Science and Plant Analysis 19: 91–1016.
- Hanway, J. J. 1963. Growth stages of corn. Agronomy Journal 55: 487–492.
- Luebs, R. E., G. Stanfoed, and A. D. Scott. 1956. Relation of available potassium to soil moisture. Soil Science Society of America Journal 20: 45–50.
- Mallarino, A. P., and S. L Higashi. 2009. Assessment of potassium supply for corn by analysis of plant parts. Soil Science Society of America Journal 73: 2177–2183.
- Mallarino, A. P., J. E. Sawyer, and S. K. Barnhart. 2013. A general guide for crop nutrient and limestone recommendations in Iowa. Iowa State University Extension Circular PM 1688. Ames, IA: Iowa State University Extension.
- McLean, E. O., and M. E. Watson. 1985. Soil measurements of plant available potassium. In: Potassium in Agriculture, ed. R. D. Mudson, pp.277–308. Madison, WI: ASA, CSSA, and SSSA.
- Murrell, T. S. 2011. Why are soil test potassium levels so variable over time in the Corn Belt? Available online at http://fyi.uwex.edu/discoveryfarms/files/2011/06/murrell-k-variability.pdf (accessed 13 March 2014).
- Nathan, M., and NCERA-13 Soil Testing and Plant Analysis Committee. 2011. Recommended Soil Test Procedures for the North Central Region. Columbia, MO: University of Missouri.
- http://ndawn.ndsu.nodak.edu/. 2013. Natural Resources Conservation Service, United States Department of Agriculture. Official Soil Series Descriptions. Available online at http://www.nrcs.usda.gov/wps/portal/nrcs/site/soils/home/ (accessed 4 February 2014).
- Thomas, G. W. 1996. Soil pH and soil acidity. In: Methods of Soil Analysis. Part 3, ed. D. L. Sparks, pp. 475–490. Madison, WI, USA: ASA and SSSA.
- Vyn, T. J., and K. J. Janovicek. 2001. Potassium placement and tillage system effects on corn response following long term no till. Agronomy Journal 38: 173–185.
- Warncke, D., and J. R. Brown. 1998. Potassium and other basic cations. In: Recommended Chemical Soil Test Procedures for the North Central Region, North Central Regional Publ.. 221 ( rev.), ed. J. L. Brown, pp. 31–33. Columbia, MO: University of Missouri.
- Welch, L. F., and R. L. Flannery. 1985. Potassium nutrition of corn. In: Potassium in Agriculture, ed. D. R. Munson, pp. 647–664. Madison, WI: ASA, CSSA and SSSA.