Speaker
Description
The recognized impacts of phytosanitary products on human and ecosystems health call for a deep modification of cropping systems. In Brittany, cropping systems are mainly aimed at providing animal feed. If the breeding of ruminants allows the valorization of fodder and therefore the presence of perennial crops in rotations, this is not the case with the breeding of monogastric animals. In these systems, reducing the use of phytosanitary products is challenged by the difficulty of controlling weeds in rotations composed solely of annual crops.
Three cropping systems with little or no use of phytosanitary products were tested from 2018 to 2023, as part of the DEPHY EXPE 2 Syno’phyt project. Crop rotations were designed to provide feed to pig or poultry farming (grains, oilseeds and protein crops). Pest management strategies and associated decision rules were co-constructed within the framework of workshops organized regularly during the first two years of the project, gathering stakeholders from varied backgrounds (INRAE, technical institutes, farmers…). The three systems are: “Reference 2025 system” (SR), based on a corn-wheat rotation, reducing by half the use of phytosanitary products compared to the Breton average IFT of a corn-wheat rotation; “Agroecological system” (SA), based on a 7-year rotation integrating protein crops, reducing the use of phytosanitary products by 75% compared to this same reference; “Organic farming system” (SAB), based on a 5-year rotation integrating protein crops and crops intended for human food, without using any phytosanitary products. These three systems were implemented at the Kerguéhennec experimental station, in the center of Morbihan. All crops were present each year. The systems were monitored for 5 growing seasons. The data collected during these 5 years concerns (i) the technical itineraries, recorded under Systerre tool; (ii) crop yield components, (iii) crop health status, (iv) weed density and biomass. The systems were evaluated on their agronomic, economic and working time performances.
The results show satisfactory agronomic performances: in SR, the yield objectives are achieved 2 out of 5 years for wheat and 4 out of 5 years for corn; in SA, 3 out of 5 years for wheat and corn, 5 out of 5 years for rapeseed, 1 out of 5 years for field bean, 2 out of 5 years for triticale and pea association; in SAB, 4 out of 5 years for oats, field bean and corn, 2 out of 5 years for buckwheat and triticale-pea association. The management of annual and perennial weeds is satisfactory in SA and SR, satisfactory for annuals but very unsatisfactory for perennials in the SAB. The average margin over the 5 years is 1066 ± 187 €/ha in SAB, 974 ± 138 €/ha in SR and 895 ± 96 €/ha in SA. Working time is increased by 1 hour on average in SR (7h35/ha) compared to SAB and SA which have similar working times, 6h29/ha and 6h43/ha respectively. The work schedule is very different from one system to another, with work peaks more pronounced in the SR. The results of this trial show that reducing phytosanitary products is possible without extending the rotation but at the expense of working time. Weed management was satisfactory in experimented systems, with a vigilance on the management of perennials in these rotations solely composed of annual crops. The choice of cultivated species was consistent with the initial constraints of the project (link to breeding), but questions emerge regarding the structuring of the agri-food sector, in terms of valorization of “minor” crops and the possibility of collecting and sorting crop associations managed conventionally.
| Keywords | cropping systems; phytosanitary products; organic farming; performances; diversification |
|---|
