MINERAL DYNAMICS IN PERENNIAL RYEGRASS AS INFLUENCED BY CROP MANAGEMENT AND PLOIDY

The effects of cutting/fertility management and ploidy type on the apparent recovery efficiencies of N, P and K, and the seasonal uptakes and average concentrations of minerals (P, K, Ca, Mg, S, Fe, Mn, Zn, Cu, Mo, B and Na) were studied over three production years in four diploid and four tetraploid cultivars of perennial ryegrass (Lolium perenne L.). Two systems of management were studied — four cuts a year with 300:87:165 kg ha−1 of N:P:K (4C-300N) and eight cuts a year with 450:131:248 kg ha−1 (8C-450N). The statistically significant (P < 0.05) treatment effects that resulted in responses of biological importance included the management system, the production year, the cultivar (within ploidy type), and the production year × management system interaction; ploidy had no agronomically significant effect. The production year × management system interaction had biologically important effects on the apparent recovery efficiency of N, the uptake of Mg, S and Fe, and the tissue concentration of Fe. The appar...