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Potassium fertilization of timothy‐based cut grassland—Effects on herbage yield, mineral composition and critical K concentration on soils with different K status
Author(s) -
Lunnan T.,
Øgaard A. F.,
Krogstad T.
Publication year - 2018
Publication title -
grass and forage science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.716
H-Index - 56
eISSN - 1365-2494
pISSN - 0142-5242
DOI - 10.1111/gfs.12341
Subject(s) - potassium , chemistry , fertilizer , agronomy , soil water , composition (language) , yield (engineering) , zoology , tetany , human fertilization , phosphorus , grassland , nitrogen , milking , environmental science , biology , soil science , linguistics , philosophy , materials science , organic chemistry , metallurgy , endocrinology
Herbage yield responses to K fertilizer application are variable in Norwegian grassland. Excessive K application may increase the risk of grass tetany (hypomagnesaemia) and milk fever (hypocalcaemia). We analysed a series of K fertilizer experiments on grassland with respect to their herbage yields and mineral composition. Our results show the importance of native soil K reserves when considering the need for K application. Soils with a high content of acid‐soluble K showed no response to K fertilizer application. The critical K content in grass with respect to yield was estimated to be 17.7 g K/kg DM in the first cut and 20.3 kg K/ DM in the second cut, while the critical K/N relationship was found to be 0.83 when a maximum yield reduction of 2.5% was used as a criterion. In these trials, soils with a high content of acid‐soluble K had the greatest risk of grass tetany and the highest values of cation–anion balance. Application of potassium chloride had little effect on the cation–anion balance, and thereby the risk of milking fever, because there was a corresponding uptake of K and Cl ions.