Potassium

Extension Publications

• CROP 3153 Phosphorus and Potassium Tissue Testing in Corn and Soybean
• PM 869 Fertilizing Pastures
• PM 1688 A General Guide for Crop Nutrient and Limestone Recommendations in Iowa
• PM 3052c Nutrient Considerations with Corn Stover Harvest

Presentations

• Soil phosphorus and potassium dynamics and management. A.P. Mallarino. 2020. Soil fertility and nutrient management short course. Iowa State University Extension and Outreach, Ames.
• Site-specific soil fertility management, with emphasis on P, K, and lime. A.P. Mallarino. 2020. Soil fertility and nutrient management short course. Iowa State University Extension and Outreach, Ames.

Newsletter Articles

• Nutrient Replacement with Corn and Soybean Stover Removal (10/2024)
• Fall Phosphorus and Potassium Fertilization Decisions with Variable Prices (9/2023)
• Plant Tissue Testing may be Useful this Season but be Aware of Potential Drought Effects (6/2023)
• Phosphorus and Potassium Soil-Test Interpretation Guidelines Have Changed (2/2023)
• Cold Spring and High Fertilizer Prices may Make Starter Fertilizer More Important (4/2022)
• Wind damaged corn - nutrient content? (8/2020)
• Phosphorus and potassium management for 2020 after a year with highly variable yields (10/2019)
• You couldn’t apply phosphorus and potassium last fall and now it’s too wet (4/2018)
• Fertilization can help with cool soils and late planting dates (4/2018)
• Upper soybean leaves began showing potassium deficiency symptoms since early August in some Iowa fields (8/2019)
• Phosphorus and potassium in silage harvest of drought-damaged corn (7/2017)

View newsletter articles 2016 and earlier -- click here to expand

• Value of soybean tissue testing for phosphorus and potassium (6/2016)
• Research shows a role for phosphorus and potassium tissue testing in corn (6/2016)
• Make rational decisions about phosphorus and potassium management with unfavorable crop prices (9/2015)
• Starter fertilization sometimes boosts corn yield (3/2015)
• Phosphorus, potassium, and pH management issues following drought-damaged crops (8/2012)
• Phosphorus and potassium in silage harvest of drought-damaged corn (7/2012)
• Why are potassium deficiency symptoms showing now in corn and soybeans? (6/2012)
• Is it iron or potassium deficiency? (7/2002)
• Corn leaf potassium deficiency symptoms (7/2002)
• Corn and soybean responses to deep-band phosphorus and potassium (9/2000)
• Potassium deficiency symptoms in corn (6/2000)

Conference Proceedings and Reports

• Larson, A., E. Heaton, N. Boersma, J. Studt, S. Emran, and A. VanLoocke. 2024. Effect of phosphorus and potassium application on the growth and yield of a 14-year-old Miscanthus x giganteus stand. Proceedings, 54th North Central Soil Fertility Conf., Nov. 20-21, 2024.
• Mallarino, A.P. 2023. Iowa P and K soil-test interpretations were updated in 2023: Changes and Reasons. Proceedings, 53rd North Central Soil Fertility Conf., Nov. 1516, 2023.
• Mallarino, A.P. 2023. Evaluation of sidedress fluid potassium fertilizer for soybean production. Final Project Report to Corteva Agriscience and The Fluid Fertilizer Foundation.
• Mallarino, A.P. 2020. Evaluation of post-emergence fluid potassium fertilizer application for corn production. Final Project Report to Corteva Agriscience and The Fluid Fertilizer Foundation.
• Mallarino, A.P., L.B. Thompson, J. Sievers, and T. Tuttle. 2020. Long-term phosphorus and potassium placement methods and application rates for corn and soybean managed with no-tillage and tillage. Iowa State Univ. Research and Demonstration Farms Progress Reports 2019. RFR-A1968.
• Mallarino, A.P., 2019. Phosphorus and potassium fertilizer placement options when crop prices are low. p. 123-130. In 31th Integrated Crop Management Conf. Proceedings. Dec. 4-5. 29-30, 2019. Iowa State Univ. Extension.
• Mallarino, A.P., 2019. Efficacy of variable-rate application technology for phosphorus, potassium, and lime management. In 49th North-Central Extension-Industry Soil Fertility Conf. Proceedings. Nov. 5-6. Des Moines, IA.
• Mallarino, A.P., 2018. Corn and soybean grain yield, phosphorus and potassium removal, and soil-test trend responses to long-term fertilization strategies. p. 83-90. In 30th Integrated Crop Management Conf. Proceedings. Nov. 28-29, 2018. Iowa State Univ. Extension.
• Mallarino, A.P. 2017. Watch potassium management - It also affects corn response to nitrogen and soybean diseases. p. 153-159. In The Integrated Crop Management Conf. Proceedings. Nov. 30-Nov. 29-30, 2017. Iowa State Univ. Extension.
• Hirniak, J.N., and A.P. Mallarino. 2017. Nitrogen and potassium interactions in corn. p. 103-108. In 47th North-Central Extension-Industry Soil Fertility Conf. Proceedings. 15-16 Nov. 2017.
• Mallarino, A.P., J. Hirniak, R. Oltmans, and M. Schnabel. 2017. Continuous corn response to nitrogen and potassium in northern Iowa. Farm Progress Reports: Vol. 2016: Iss. 1, Article 85.
• Mallarino, A.P., R.R. Oltmans, and N. Piekema. 2017. Long-term potassium fertilization effects on yield of corn and soybean in south central Iowa. Farm Progress Reports: Vol. 2016: Iss. 1, Article 186.
Mallarino, A.P., and K. Pecinovsky. 2017. Phosphorus and potassium placement for corn and soybean managed with tillage or no-tillage. Farm Progress Reports: Vol. 2016: Iss. 1, Article 76.

View conference proceedings and reports 2016 and earlier -- click here to expand

• Mallarino, A.P. 2016. Value of tissue testing to improve phosphorus, potassium, and micronutrients management for corn and soybean. p. 139-146. In The Integrated Crop Management Conf. Proceedings. Nov. 30-Dec. 1, 2016. Iowa State Univ. Extension.
• Mallarino, A.P. 2016. What can long term experiments provide for improving phosphorus and potassium management? p. 12-16. In 65th North-Central Extension-Industry Soil Fertility Conf. Proceedings. Nov. 2-3 2016. Vol. 32. Des Moines, IA. International Plant Nutrition Institute, Brookings, SD.
• Mallarino, A.P., B. Havlovic, and D. Schaben. 2016. Effects of phosphorus and potassium placement on yield of corn and soybean managed with tillage or no tillage. Armstrong and Neely-Kinyon Research and Demonstration Farms Annual Reports. ISRF15-12, RFR-A1594. Iowa State Univ., Ames, IA.
• Mallarino, A.P., R. Oltmans, and M. Rees. 2016. Continuous corn response to nitrogen, potassium, and sulfur in southeast Iowa. Southeast Research and Demonstration Farm Annual Reports. ISRF15-34, RFR-A1588. Iowa State Univ., Ames, IA.
• Mallarino, A.P., and J. Sievers. 2016. Phosphorus and potassium placement and application rates for corn and soybean managed with no-till or tillage. Northwest Research Farm and Allee Demonstration Farm Annual Reports. ISRF15-29,31, RFR-A1563. Iowa State Univ., Ames, IA.
• Mallarino, A.P. 2015. Making rational adjustments to phosphorus, potassium, and lime application rates when crop prices are low and producers want to cut inputs. p. 149-155. In The Integrated Crop Management Conf. Proceedings. Dec. 2-3, 2015. Iowa State Univ. Extension.
• Mallarino, A.P. 2014. Making rational adjustments to phosphorus, potassium, and lime application rates when crop prices are low and  producers want to cut inputs. p. 137-143. In The Integrated Crop Management Conf. Proceedings. Dec. 3-4, 2014. Iowa State Univ. Extension.
• Mallarino, A.P., and R.R. Oltmans. 2014. Potassium management, soil testing and crop response. p. 45-52. In 44th North-Central Extension-Industry Soil Fertility Conf. Proceedings. Nov. 19-20 2014. Vol. 30. Des Moines, IA. International Plant Nutrition Institute, Brookings, SD.
• Mallarino, A.P., R.R. Oltmans, and M.W. Fiscus. 2013. Potassium effects on yield of corn and soybean and on potassium uptake and recycling to the soil. Agric. Eng., Agronomy, and Central Iowa Research Farms Annual Reports. ISRF12-16,30. Iowa State Univ., Ames, IA.
• Mallarino, A.P., R.R. Oltmans, and B. Havlovic. 2013. Potassium uptake and recycling to the soil in corn and soybean. Armstrong and Neely-Kinyon Research and Demonstration Farms Annual Reports. ISRF12-12. Iowa State Univ., Ames, IA.
• Mallarino, A.P., R.R. Oltmans, and N. Piekema. 2013. Potassium fertilizer effects on yield of corn and soybean and on potassium uptake and recycling to the soil. McNay Memorial Research and Demonstration Farm. ISRF12-35. Iowa State Univ., Ames, IA.
• Mallarino, A.P., R.R. Oltmans, and D. Rueber. 2013. Corn and soybean potassium uptake, removal with grain, and recycling to the soil. Northern Research and Demonstration Farm Annual Reports. ISRF12-22. Iowa State Univ., Ames, IA.
• Mallarino, A.P., R.R. Oltmans, M. Rees, and K. Van Dee. 2013. Potassium uptake and recycling to the soil in corn and soybean. Southeast Research and Demonstration Farm Annual Reports. ISRF12-34. Iowa State Univ., Ames, IA.
• Mallarino, A.P., R.R. Oltmans, L.M. Thompson, and K.T. Pecinovsky. 2013. Corn and soybean potassium uptake, removal with harvest, and recycling to the soil. Northeast Research and Demonstration Farm Annual Reports. ISRF12-13. Iowa State Univ., Ames, IA.
• Sawyer, J.E., and A.P. Mallarino. 2012. Nutrient considerations with corn silage and stover harvest. p. 131-136. In The Integrated Crop Management Conf. Proceedings. Nov. 28-29, 2012. Iowa State Univ. Extension.
• Mallarino, A.P., R.R. Oltmans, J.R. Prater, C.X. Villavicencio, and L.B. Thompson. 2011. Nutrient Uptake by Corn and Soybean, Removal, and Recycling with Crop Residue. p. 103-113. In Proc. 23rd Annual Integrated Crop Management Conf., Ames, IA 30 Nov. – 1 Dec. 2011. Iowa State Univ., Ames, IA
• Oltmans, R.R., and A.P. 2011. Phosphorus and potassium removal and leaching from residue in corn and soybean. p. 197-202. In North-Central Extension-Industry Soil Fertility Conf. Proceedings. Nov. 16-17. Vol. 27. Des Moines, IA
• Mallarino, A.P. 2009. Phosphorus and potassium placement methods for corn and soybean: an Iowa perspective. p. 109-115. In Proc. 2009 Wisconsin Crop Management Conf., Madison, WI. Vol. 48. Univ. Wisconsin-Extension and College of Ag. And Life Sciences, Univ. of Wisconsin-Madison, WI.
• Mallarino, A.P., and M.W. Clover. 2009. Do new corn hybrids and yield levels influence potassium fertilizer management? p. 125-131. In The Integrated Crop Management Conf. Proceedings. Dec. 2-3, 2009. Ames, IA. Iowa State Univ. Extension.
• Mallarino, A.P. 2008. Fertilizing crops in the new price age - phosphorus and potassium. p. 261-266. In Proc. 20th Annual Integrated Crop Manag. Conf., Ames, IA. 10-11 Dec. 2008. Iowa State Univ., Ames, IA
• Clover, M.W., A.P. Mallarino, and P.A. Barbagelata. 2007. Corn and soybean grain yield and concentration of potassium in plant tissues and soil as affected by potassium fertilization. p. 119-125. In Proc. Thirty-Seventh North Central Extension-Industry Soil Fertility Conf., Des Moines, IA. 14-15 Nov. 2007. Vol. 23. International Plant Nutrient Inst., Brookings, SD.
• Mallarino, A.P., and D.J. Wittry. 2006. Variable-rate application for phosphorus and potassium: impacts on yield and nutrient management. p. 219-224. In Proc. 18th  Annual Integrated Crop Manag. Conf., Ames, IA. 29-30 Nov. 2006. Iowa State Univ., Ames, IA.
• Mallarino, A.P., P.A. Barbagelata, and K. Van Dee. 2005. Potassium fertilization effects on soil-test potassium and yields of corn and soybeans. p. 26-27. In Annual progress reports-2004. Northwest Research and Demonstration farm. ISRF04-34. Iowa State Univ., Ames, IA.
• Mallarino, A.P., and D. Rueber. 2005. Phosphorus and potassium fertilization and placement methods for corn-soybean rotations managed with no-till and chisel plow tillage. p. 12-13. In Annual progress reports-2004. Northern Research and Demonstration farm. ISRF04-22. Iowa State Univ., Ames, IA.
• Mallarino, A.P., and K. Pecinovsky. 2005. Phosphorus and potassium placement methods for corn and soybeans managed with no-till and chisel plow tillage. p. 44-45. In Annual progress reports-2004. Northeast research and demonstration farm. ISRF04-13.
• Mallarino, A.P., P.A. Barbagelata, and D.J. Wittry. 2004. Soil-test potassium field calibrations for soybean Iowa interpretations and research update. p. 67-70. In North-Central Extension-Industry Soil Fertility Conf. Proceedings. Vol. 20. Des Moines, IA.
• Mallarino, A.P., and K. Pecinovsky. 2004. Long-term phosphorus and potassium fertilization strategies for corn-soybean rotations. p. 22-23. In Annual progress reports-2003. Northeast research and demonstration farm. ISRF03-13. Iowa State Univ., Ames, IA.
• Mallarino, A.P., and D. Haden. 2004. Phosphorus and potassium placement for corn and soybeans managed with no-till and chisel-disk tillage. p. 14-15. In Annual progress reports-2003. Northwest research and demonstration farm. ISRF03-29,31. Iowa State Univ., Ames, IA.
• Mallarino, A.P., B. Havlovic, and J. Butler. 2004. Phosphorus and potassium fertilizer placement for corn and soybeans managed with no-till and chisel-disk tillage. p. 19-20. In Annual progress reports-2003. Armstrong research and demonstration farm. ISRF00-12. Iowa State Univ., Ames, IA.
• Mallarino, A.P. 2003. Starter and foliar fertilization. Are they needed to supplement primary fertilization? p. 113-120. In The Integrated Crop Management Conf. Proceedings. Dec. 3-4, Ames, IA. Iowa State Univ. Extension.
• Kaiser, D.E., A.P. Mallarino, and M. Bermudez. 2003. In-furrow starter and broadcast phosphorus and potassium fertilization for corn. p. 186-189. In North-Central Extension-Industry Soil Fertility Conf. Proceedings. Vol. 19. Des Moines, IA.
• Mallarino, A.P., and D. Rueber. 2003. Long-term evaluation of nitrogen, phosphorus, potassium, and lime requirements of continuous corn. p. 7-8 In Annual progress reports-2002. Northern Research and Demonstration farm. ISRF02-22. Iowa State Univ., Ames, IA.
• Mallarino, A.P., and K. Van Dee. 2003. Phosphorus and potassium placement for corn and soybeans managed with no-till and chisel-plow tillage. Annual progress reports-2002. Northwest Research and Demonstration farm. ISRF02-34. Iowa State Univ., Ames, IA.
• Mallarino, A.P., and D. Wittry. 2000. How can we make intensive soil sampling and variable-rate P and K fertilization cost-effective? p. 203-210. In The Integrated Crop Management Conf. Proceedings. Nov. 29-30, 2000. Ames, IA. Iowa State Univ. Extension
• Mallarino, A.P., R. Borges, and D. Wittry. 2001. Corn and soybean response to potassium fertilization and placement. p. 5-11. In North-Central Extension-Industry Soil Fertility Conf. Proceedings. Vol. 16. Des Moines, IA.
• Mallarino, A.P., and D. Rueber. 2000. Long-term potassium fertilization for the corn-soybean rotation. p. 31-33. In Annual progress reports-1999. Northern research and demonstration farm. ISRF99-22. Iowa State Univ., Ames, IA.
• Mallarino, A.P. 1999. Alternatives for P and K management: A role for deep banding and starter? p. 247-253. In The Integrated Crop Management Conference. Proceedings. Dec. 1-2, 1999. Iowa State Univ. Extension. Ames, IA.
• Sawyer, J.E. and D. Barker. 1999. Foliar fertilization of corn with mono-potassium phosphate and urea. Final research report. Iowa State Univ., Ames, IA
• Mallarino, A.P., D.W. Barker, R. Borges, and J.C. North. 1998. Tillage and fertilizer placement for the corn-soybean rotation. p. 231-237. In The Integrated Crop Management Conference. Proceedings. Nov. 17-18, 1998. Iowa State Univ. Extension, Ames, IA.
• Mallarino, A.P., and Haq, M.U. 1998. Foliar fertilization of soybeans. p. 20-26. In North Central Extension-Industry Soil Fertility Conference. Proceedings. Vol. 14. St. Louis, MO.
• Mallarino, A.P., and T.S. Murrell. 1998. No-till corn grain yield responses to band applications of potassium. Better Crops 82: 4-6.
• Mallarino, A.P., and R. Borges. 1997. Deep banding phosphorus and potassium for no-till corn and soybeans. p.129-135. In North Central Extension-Industry Soil Fertility Conference. Proceedings. Vol. 13. St. Louis, MO.

Featured

Quick Links

Corn Nitrogen Rate Calculator

ISU Extension and Outreach Store

ISU Integrated Crop Management

ISU Integrated Crop Management Blog

North Central Extension-Industry Soil Fertility Conference