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Fertilizer requirements for maintenance of a perennial ryegrass ( Lolium perenne L.)/white clover ( Trifolium repens L.) pasture growing on a humus iron podzol in N.E. Scotland
Author(s) -
RANGELEY ANNE
Publication year - 1988
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/j.1365-2494.1988.tb02151.x
Subject(s) - lolium perenne , perennial plant , agronomy , trifolium repens , lime , fertilizer , pasture , dry matter , humus , trifolium subterraneum , biology , soil water , ecology , paleontology
Ryegrass/white clover pastures were reseeded on heather moor in north‐cast Scotland in 1978/79. By 1981, despite moderate fertilizer applications, the pastures had deteriorated and dry matter (DM) production was low. After preliminary soil and herbage analysis an omission trial was carried out in 1982/83 at two sites (A and B) to identify the factors which limited production. At site A depressions in growth occurred in the absence of N, P and K. Perennial ryegrass was severely N deficient with concentrations in leaves of less than 22 g N kg −1 in spring and summer even after application of 120 kg N ha −1 annually. Rates of nitrogen fixation were high in spring but rapidly declined in June and July as the soil moisture tension increased. Application of N fertilizer also reduced the N 2 fixation rate. Deficiencies of F and K occurred despite apparently high levels of extractable F in the soil. Uptake of these nutrients was inhibited in the dry soil during the summer. White clover was more susceptible to drought than perennial ryegrass, probably because it rooted at a shallower depth. Growth at site B was limited by acidity and lack of N and K. The soil pH was 4 8 (s.d. = 0middot;75) at 1‐5 cm depth. Application of 2 5 t lime ha −1 in spring 1982 had not altered the pH by autumn 1983. It was concluded that methods of incorporating lime into the soil, together with ways of increasing the rates of N 2 fixation by white clover and transfer to grass, should be investigated further. Regular small applications of N and K may be necessary to sustain DM production at the level required by the farming system.