Influence of sodium and potassium fertilization on the sodium concentration of timothy

Authors

• Tommi Peltovuori Department of Applied Chemistry and Microbiology, PO Box 27, FIN-00014 University of Helsinki, Finland
• Markku Yli-Halla Department of Applied Chemistry and Microbiology, FIN-00014 University of Helsinki, Finland

DOI: https://doi.org/10.23986/afsci.72789

Abstract

Sodium (Na) concentration of forage crops grown in Finland, particularly that of timothy, is much lower than is recommended in the feed of cattle. A pot experiment was carried out on clay, loam and organogenic soils to find out the effect of Na application (0, 200 or 400 mg dm-3 of soil, one application) on the concentration of Na, K, Ca and Mg of timothy and the effect of K fertilization (0, 100 and 200 mg dm-3 for each three harvests) on the efficiency of Na application. Added Na elevated the Na concentration in all harvests on all soils. The magnitude of the effect (organogenic soils≥loam>clay) was opposite to the K supplying power of the soil. Potassium fertilization suppressed the effect of Na application substantially and Na concentration was elevated remarkably only when the K concentration of the plants fell to or below the deficiency level (approximately 15 g kg-1). According to a cation exchange experiment, nearly all added Na remained in the soil solution. Still, the apparent utilization of added Na remained below 4% on all soils, demonstrating the natrophobic nature of timothy. Sodium fertilization of timothy seems to be an ineffective way of increasing the Na content of forage at least on soils of a good K status or when applied with ample K fertilization.