Poultry for biological control of weeds in orchards

Introduction. Because of the humid tropical conditions, weed control is an important and permanent job in the outlay of a fruit producer in the West Indies. The practice of chemical weed control is to date the cheapest, but the recurring use of herbicides in the orchards of Martinique leads to soil erosion and water pollution. To mitigate the use of herbicides, we tested the association of poultry with a productive orchard in order to control the weeds. Materials and methods. The system was installed on a plot of 700 m(2) divided into seven plots of 100 m(2). Two plots were the control treatments and were mowed with a brush cutter. Each of the other five plots was subjected to five geese grazing for a week, then to 20 chickens grazing during the following week, then the plot was left without poultry for three more weeks. Three cycles of such rotations were observed (4 months). Biomass production by botanical groups (Poaceae, Cyperaceae and others) in the experimental plots was measured each week for four months. A monthly index of recovery by botanical group was noted. Results. The total biomass of the herbaceous cover decreased on grazed plots, which allowed the biological control of weeds for four months. Species diversity decreased because of the selection made by poultry for food and cover was homogenized by the percentage increase in biomass of Cyperaceae in the total biomass. This group, the least palatable for poultry, thus flourished on all plots grazed. Discussion. Poultry grazing, particularly geese, proved to be a promising method for controlling weeds in orchards. However, in the case of a high proportion of unpalatable species in the herbaceous cover, other weed control methods should be combined. The installation of a grass cover composed of a mixture of cover crops adapted to the combination of orchard and poultry as well as better management of the animal rotation should be considered to optimize this technique.