Submitted to: Crop Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 17, 2009
Publication Date: February 16, 2010
Citation: Bruns, H.A., Abbas, H.K. 2010. Additional potassium did not decrease aflatoxin or fumonisin nor increase corn yields. Crop Management. doi: 10.1094/CM-2010-0216-01-RS. Interpretive Summary: Potassium helps corn resist infection by a number of fungal diseases and may help reduce aflatoxin and fumonisin (compounds toxic to animals) contamination of the grain by reducing the infection of the fungi (molds) that produce these toxins. Two experiments run at Stoneville, MS on potassium fertility in corn showed no increase in grain yield or reductions in aflatoxin or fumonisin contamination as the potassium fertilizer levels increased from no additional fertilizer to 120 pounds per acre. Even a split application of 60 pounds of fertilizer applied per acre before planting followed by an equal amount applied when the corn plant had six leaves failed to produce any change. This was true even when different corn hybrids were planted and when the number of corn plants grown per acre differed in experiments conducted for three years with irrigation in two different fields. Applying more potassium fertilizer than what is currently recommended for corn production in the Mid South is of no benefit in controlling aflatoxin or fumonisin contamination.
Technical Abstract: Potassium (K) aids in maintaining the water status of corn (Zea mays L) and helps plants to resist infection by some fungal pathogens. Two experiments involving muriate of potash fertilizer treatments of 0 lbs/A K2O, 60 lbs/A K2O, 120 lbs/A K2O, or a split application of 60 lbs/A K2O pre-plant followed by another application of 60 lbs/A K2O at growth stage V6 were conducted on a Beulah fine sandy loam (coarse-loamy, mixed thermic Typic Dystrochrepts) (Site 1) and a Dundee silty clay (fine-silty, mixed, thermic Aeric Ochraqualfs) (Site 2) at Stoneville, MS in 2004, 2006, and 2007 for determining K effects on grain yield and aflatoxin and fumonisin contamination. Soil tests showed Site 1 to require 60 lbs/A additional K2O to achieve a 200 bu/A grain yield and Site 2 90 lbs/A K2O. Experiment 1 consisted of one hybrid and plant populations of 27 000, 30 000, 33 000, or 36 000 plants/A while Experiment 2 included four hybrids seeded at 35 000 plants/A. Both experiments were furrow irrigated and grown using a randomized complete block design replicated five times with treatments factorially arranged. Added K fertilizer had no positive effect on grain yield nor reduced mycotoxin contamination. Observed differences in data were mainly among years which resulted from differences in natural rainfall patterns during the duration of the study, regardless of the use of supplemental furrow irrigation. Supplemental K fertilizer has been determined in other research to be needed for good plant health and grain yields in corn when soil tests levels for the nutrient are low. Current recommendations of N, P2O5, and K2O fertilizer appear adequate for both high grain yields and low mycotoxin contamination.