A formula for calculating the potential photosynthesis of a closed crop surface is proposed, assuming that the leaves of the crop are not arranged in any definite direction. In the Netherlands, values for potential photosynthesis vary from 290 kg. CH2O/ha./day in June to 50 kg./ha./day in December.
Results from an experiment in which rye was sown in permanent grassland appeared to indicate that the growth of the rye was limited by lack of N. In further trials, rye was drilled at 200 kg seed/ha in rows 20 cm apart into a sward of permanent grassland on (a) 1 or (b) 24 Oct. 1959. Plots with and without rye were mown on 22 Oct., given 30 kg N/ha...
Starting from work with annuals a model of competition between herbage plants is discussed. It is shown that their mutual interference can only be described adequately if they are grown in mixture and also in monoculture
Theoretical relationships between world potential photosynthetic productivity and the world population able to be supported therefrom are discussed.