Assessment of a pesticide-free arable cropping system in a long-term field trial

Pesticide-free arable cropping systems: performances, learnings and technical lock-ins from a French long-term field trial

The aim of this study was to assess the medium-term performances of a pesticide-free (but allowing the use of synthetic fertilizers) cropping system, designed to achieve high yields while meeting a multiplicity of environmental objectives. This system was compared with a low-input cropping system designed to meet the same environmental objectives (PHEP: Productive with High Environmental Performances). This assessment carried out over eleven years, took place in a field trial in the Paris Basin (France). The ban of pesticides did not result in any significant difference in average yield between systems across the crop sequence. However, the yields of some crops were significantly reduced. In the pesticide-free system, the technological quality of cereal grains was not penalized. Most agri-environmental indicators showed better performance in the pesticide-free system. However, fuel consumption and labor time per hectare for weed control were significantly higher. The study identified highly effective farming strategies for avoiding pesticide use, as well as several technical bottlenecks limiting regular production in pesticide-free systems.

To ensure regular and high yields, current agriculture is based on intensive use of pesticides and fertilizers, which are detrimental to the environment and human health. Moreover, as pest resistance to pesticides increases, and more and more pesticides are taken off the market, national and European policies are becoming powerful drivers to deliver pesticide-free farming systems. Whereas numerous studies have compared organic versus conventional systems, there is no medium-term study isolating the "pesticide-free" character of an experimental system.

The study compared a pesticide-free cropping system (No-Pest), using synthetic fertilizers, and designed to produce high yields, and to meet a multiplicity of environmental objectives. This system was compared to a low-input cropping system designed with the same environmental targets (PHEP: Productive with High Environmental Performances). This evaluation was carried out on the AgroParisTech farm in the Paris region (France), over eleven years (2009-2019). The ban on pesticide use did not result in any significant difference in average yield across the crop sequence (expressed in GJ.ha-1.yr-1, or kg N.ha-1.yr1). However, the yields of some crops fell sharply, either because of pest damage (in the case of faba beans), or because of limited nitrogen nutrition (in the case of soft wheat).

In the No-Pest system, the mycotoxin content of cereals was below the regulatory threshold, and the average protein content of wheat was above the standard required for baking. Indirect energy consumption, total greenhouse gas emissions, number of technical operations, quantities of nitrogen fertilizers and processing frequency indices were significantly lower than those of the PHEP system. However, direct energy consumption, direct greenhouse gas emissions and working time for weed control were significantly higher. In this experiment, we identified highly effective farming strategies to avoid pesticide use (a highly diversified and long crop sequence with minor species) and several technical bottlenecks limiting regular production in pesticide-free systems.

More work should be undertaken to provide technical knowledge on the management of major or orphan species in pesticide-free systems, and to provide additional results, particularly relating to the economic and social performances of these systems.

References:

Colnenne-David C., Jeuffroy M.H., Grandeau G., Doré T., 2022. Pesticide-free cropping system: performances, learnings and technical locks from a field trial. Congress “What research to meet the pesticides reduction objectives embedded in the European Green Deal?”, Dijon. (oral)

Colnenne-David C., Jeuffroy M.H., Grandeau G., Doré T., 2023. Pesticide-free arable cropping systems: performances, learnings and technical lock-ins from a French long-term field trial. Agronomy for Sustainable Development, https://doi.org/10.1007/s.13597-023-00931-7

Modification date : 05 December 2023 | Publication date : 22 November 2023 | Redactor : OR