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Research article2009Peer reviewed

Radiation-use efficiency in leys: influences of growth period and clover proportion

Riesinger, P.; Eckersten, Henrik; Torssell, Bengt; Forkman, Johannes


Acquisition of carbohydrates and their partitioning to storage organs are decisive attributes for the persistence of perennial leys. It was therefore of interest to analyse radiation-use efficiency (RUE) and root allocation (br) in one-, two-, and three-year-old red clover-grass leys as functions of growth period (first and second growth, ley age), proportion of clover, and site properties (location, soil type, humus content). By calibrating RUE and br, the ley yields simulated with a growth model were adjusted to the values observed during two consecutive years at 33 organic farms located in the southern and the northwestern coastal regions of Finland. Driving variables of the simulations were daily measurements of weather. RUE declined from the first to the second growth and further with ley age, while its variability increased. The value of br decreased from the first to the second growth, and was positively correlated with RUE. The high variability of RUE between different sites, and the absence of correlations between site properties and RUE, were mainly attributable to differences in overwintering and regrowth conditions. Early measurements of above-ground biomass subsequent to overwintering and cutting, and the inclusion of site-specific measurements of soil properties would have increased the general validity of the calibrated parameter values. RUE correlated positively with proportion of clover. However, the increase of the proportion of clover from the first to the second growth was not strong enough to balance the concurrent decline of RUE. With increasing ley age there were two concurrent and reinforcing patterns, namely a decrease in proportion of clover and in RUE. Thus, both symbiotic N fixation and vigour of perennial red clover-grass leys declined with ley age. With regards to RUE, however, three-year-old leys were still productive.


Clover content; Finland; growth model; mixed grassland; parameterization; red clover; root allocation; soil properties; Trifolium pratense

Published in

Acta Agriculturae Scandinavica, Section B - Soil and Plant Science
2009, Volume: 59, number: 5, pages: 465-474