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RESEARCH PRODUCT

Can we economically afford significant reduction in herbicide and nitrogen use ? Experimental evidence in real fields says, yes we can !

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EAGESTAD INRA; In Europe, several policies to limit the environmental externalities of agrochemicals have been implemented in the past decade. Yet, herbicides and fertilizers consumed over this period either have remained fairly constant or have increased. One main reason is that the fear of potential indirect negative effects on food production, hence profits. However, recent empirical studies have failed to detect a positive correlation between agrochemical use intensity and both productivity and profitability. With the present study we investigated in real farming conditions the relationships between economic benefits and weed control and nitrogen input. Through an innovative factorial experimental design set with farmers in their fields, we quantified the economic value of weed control and nitrogen use. The experiment accounted for soil variability and degree of management intensity in farming practices that ranged from organic to highly intensive users of agrochemicals. In each field, nitrogen and weed control were experimentally manipulated in intensity, allowing interactive and crossed analyses of determinants of wheat production and their economic impacts. Our results suggest that a significant proportion of farmers are not behaving optimally. Firstly, weed competition has, at best, no influence on conventional farmers’ yields. This implies that weed control strategies mainly reduce economic return. Secondly, the current nitrogen application rates are higher than what would be economically optimal, given both the costs and the benefits of nitrogen application. These findings demonstrate that there is a space for the implementation of strategies aiming at reducing certain agrochemicals, in a win-win scenario for farmers and environment.