1990/12/01 by R. W. Summers, Ron W. Summers · 1 citation
Agricultural and Biological Sciences · Environmental Science · #Agronomic Practices and Intercropping Systems #Ecology and Vegetation Dynamics Studies #Soil Carbon and Nitrogen Dynamics
paper · doi:10.2307/2404379
(1) Brent geese (Branta b. bernicla) fed on fields of winter wheat from November to March, and particularly during December to February. On undisturbed fields the feeding flock increased in size during mid-morning and remained stable until dusk when all the geese departed to the roost site. (2) Grazing of winter wheat led to a loss of c. 750% of the biomass of leaves and shoots of winter wheat. Ungrazed leaves increased in ash and fibre, and decreased in water-soluble carbohydrate content between early and midto late winter. Grazed wheat had a lower ash content and more water-soluble carbohydrates in March than ungrazed wheat. (3) Grazed wheat ripened later than ungrazed wheat. (4) Average grain yield losses were 6, 9 and 100%, respectively, on three fields where traditional scaring devices were deployed, and 7%/o when there was no scaring. Losses were due to either reduced ear density (one field), fewer grains per ear (two fields), smaller grain sizes (three fields), or a combination of these factors. (5) Straw yield was reduced by grazing on one field and the harvest index reduced on two fields. (6) Grazing did not lead to a higher biomass of weeds in the grazed plots. (7) Treading by brent geese caused slight soil compaction (shear strength) on two fields but no reduction in infiltration capacity. An experiment showed that treading, which exceeded that caused by the geese, did not significantly reduce grain yields; defoliation was responsible for the loss.