Varietal differences in uptake of ³²P labelled phosphate in clover plus ryegrass swards and monocultures

Abstract

S U M M A R YLolium perenne cv. S.23, L. multijlorum cv. RvP, and Trifolium repens cvs S. 184 and Olwen, were grown in mixed sward and monoculture during 1979. Whereas in mixtures grass roots absorbed more 32P than clover roots, in monoculture clover generally absorbed more 32P than grass roots. This showed that grass was a very strong competitor for uptake in mixed swards.Clover and grass monocultures absorbed most 32P from 10 or 15 cm depth in the soil, while grass in mixtures absorbed most 32P at 22.5 cm depth.Comparing varieties,. in monocultures in June, Olwen was most active in absorbing 32P at 15 cm. In August, Olwen absorbed more at 15 cm and 22.5 cm than S.184 or the grass varieties. Differences in absorption depth between varieties were less in mixtures than in monocultures. S.23 absorbed more 32P in the late season than RvP, both in monoculture and in mixtures. Thus Olwen differed from S. 184 in depth and timing of uptake, whilst S.23 differed from RvP in time of uptake. Such varietal differences could be exploited by manipulation of depth and timing of fertiliser application to increase the precision of sward management.0 1982 Association of Applied Biologists

Effect of three clover varieties on growth, 15N uptake and fixation by ryegrass/white clover mixtures at three sites in Wales

“…The clover variety Olwen produced more dry matter than SI84 at the lowland site and it also took up more '^N than SI84. This resembles the results of "P labelling experiments with the two varieties (Goodman and Collison, 1982). Over the whole summer season, N fixation, measured by isotope dilution, was greater in Olwen than in S184, but in September 1983 acetylene reduction was greater in SI 84 than in Olwen.…”

“…The isotope dilution equation which was used assumed that the ratio of fertilizer N uptake: soil N uptake was similar in grass and clover (Vose, 1980;Rennie, 1984). This overcomes the problem of allowing for the different root sizes known to exist between grass and clover (Goodman and Collison, 1982).…”

Effect of white clover cultivar on apparent transfer of nitrogen from clover to grass and estimation of relative turnover rates of nitrogen in roots

“…In cut plots, less than 40% of total root length has been found in the top 10 cm (Mackie-Dawson and Atkinson, 1991) which is in agreement with the proportion of 32P uptake activity by a grass/clover sward measured to I 0 cm (Goodman and Collison, 1982). In cut plots, less than 40% of total root length has been found in the top 10 cm (Mackie-Dawson and Atkinson, 1991) which is in agreement with the proportion of 32P uptake activity by a grass/clover sward measured to I 0 cm (Goodman and Collison, 1982).…”

Interactions between nitrogen, phosphorus and potassium determine growth and N2-fixation in white clover and ryegrass leys

“…Goodman and Collison (1982), using 32 P tracers, found that ryegrass was a strong competitor for P while other studies indicate that grass and clover might absorb similar amounts of 32 P (see e.g., Acuna and Wilman Fig. 4 Relations between accumulated N, P and K in the herbage at each sampling over 2 years and under varying supply of N, P and K (n = 224) 1993).…”