Potassium Sources for Soybeans

IPNI-1998-CAN-ON18

30 Mar 1999

1998 Annual Interpretive Summary

Potassium Sources for Soybeans, 1998

Little Ontario research has been done on soybean potassium (K) needs. The relative chloride (Cl) sensitivity of Ontario cultivars has not been tested. The objectives of this project were to determine whether Cl or magnesium applied with K fertilizers influence soybean response to K, and to determine whether Ontario soybean varieties differ in response to K and sources of K.

Ten selected soybean cultivars were evaluated for response to muriate of potash, sulfate of potash, and sulfate of potash-magnesia in an on-farm trial in Rodney, Ontario. The field selected had a high level of K fertility. The sulfate sources of K tended to produce higher yields, but the differences were not significant. It was concluded that Cl sources do not pose a problem for soybeans, but further research is needed to optimize K nutrition of soybean on soils of lower fertility. ON-18