Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVING ALFALFA AND OTHER FORAGE CROPS FOR BIOENERGY, LIVESTOCK PRODUCTION, AND ENVIRONMENTAL PROTECTION Title: Validating potassium fertilizer guidelines in alfalfa-corn rotations

Authors
item Yost, Matt -
item Russelle, Michael
item Coulter, Jeff -
item Sheaffer, Craig -
item Kaiser, Daniel -

Submitted to: North Central Extension Industry Soil Fertility Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: October 22, 2011
Publication Date: November 16, 2011
Citation: Yost, M.A., Russelle, M.P., Coulter, J.A., Sheaffer, C.C., Kaiser, D.E. 2011. Validating potassium fertilizer guidelines in alfalfa-corn rotations. In: Proceedings of the North Central Extension-Industry Soil Fertility Conference, November 16-17, 2011, Des Moines, Iowa. 27:20-27.

Technical Abstract: From 2008 to 2010, on-farm research was conducted on 10 fields with medium soil test K (STK) to validate Minnesota K fertilizer guidelines by determining the effect of K fertilizer applications on alfalfa yield and quality in its last production year and estimating the carryover of excess fertilizer K to first-year corn. We were surprised to find that no K fertilizer was needed to maximize alfalfa yield or overall forage feed value and quality. Luxury consumption of K occurred because as K application increased, alfalfa K concentration and K uptake increased. Even though 60 to 75% of the fertilizer K was not utilized by the alfalfa, this carryover K did not increase corn grain yield as efficiently as K applied directly to the corn. When K was applied to the corn, stover and silage yield were 10 and 8% higher, respectively, than corn that relied on carryover K alone. These results do not support the current medium soil test K (STK) range and demonstrate that applying K to first-year corn rather than last-year alfalfa may be more economical on medium- to fine-textured soils with medium STK.

Last Modified: 12/17/2014
Footer Content Back to Top of Page