Fertilisation de la canne a sucre et analyse de sol elaboration et evaluation de conseils adaptes aux structures de production en petites exploitations

摘要

Fertilizer recommendation for sugarcane is generally assessed through a leaf analysis approach. This is unsuitable in La Reunion where about 5000 farms holdings with crop diversification and heterogeneous means of production are involved in an average of 5 ha sugarcane production on small plots scattered on various soils. Thus a soil analysis approach was developed. Soil are sampled during planting, so the annual number of recommendations fit with the sugarcane plot number. An evolutionary expert system provides annually 2000 to 2500 fertilizers advices. The geographical co-ordinate of the sample allow to identify the soil type among the six exiting. The mineral threshold grid of the soil type can be used then to provide soil diagnosis and fertilizer doses, to rectify the main soil deficiency before planting and to provide annual sugarcane requirement in-between. We validate the expert system showing that the advice compared with farmers' practices induces significant productivity and environmental benefits. Nevertheless the enforcement of soil correction lead to organisational problems due to a gape between advice delivery schedule, on field fertiliser supply and planting decision. A statistical study of the spatial distribution shows that recommendation cannot be expressed on a regional basis. In response to user demand an environmental issue, we work to improve liming advice and to adapt recommendation for high yields and according to the crop residues management.