2020/03/06 by Donnat, Emilie, Vivien, Emma, Crouzet, Olivier +8
#Blé #Contaminants #Cultural practices #Degradation #Dégradation #Flow #Flux #Inputs #Intrants #Mycotoxines #Mycotoxins #Pesticides #Pratiques culturales #Pédoclimat #Residues #Résidus #Soil and climate conditions #Soils #Sols #Sunflowers #Tournesol #Trace elements #Wheat #Éléments-traces
paper · doi:10.15454/j4p0-nf37
In relation to the sanitary quality of the harvest products, the Quasagro project aimed at validating elements of global management of multicontaminant risks (mycotoxins, metallic trace elements and pesticide residues) associated with environmental factors and agronomic practices in field crops (soft wheat, durum wheat and sunflower) by multifactorial analysis: soil and climate conditions effects, crop residues, inputs and addition of organic matter. It relied on the national Quasaprove plot network, reinforced by existing field experiment. By an approach without a priori, statistical models were tested on soft wheat, based on soil or climatic parameters. No model proved to be sufficiently predictive. We also examined whether certain practices led to differences in concentration in plants. It was found that there was no difference between plowed and unplowed plots, depending on the type of fertilization, the preceding crop or the use of a CIPAN. There was no difference between plots in organic agriculture or in conventional agriculture. Whatever the crop, the balance was determined by the type of fertilization. In the case of nitrogen-only fertilization (ammonitrate), the balance was always negative. In the case of organic fertilization in organic farming, the balance was always positive and the soil accumulated trace elements. In the case of conventional agriculture with NPK fertilization, the balance was positive for arsenic, cadmium and lead, and negative for copper and zinc. The export of straws, which generated a relatively small export flow, did not change these conclusions. On the studied plots, the cumulative concentration levels observed ranged from sub-ng/g to 100 ng/g (dw) in soils. The maximum cumulated concentrations in organic farming were close to 10 ng/g. By comparison of conventional / biological technical itinerary, herbicides were markedly present in conventional and almost absent in biological; fungicides were present in biological at concentrations above the limits of quantification and the levels of fungicides were relatively similar in biological and in conventional called reasoned. The significant presence of persistent pesticides (epoxiconazole, which last treatment were several years ago) has also been highlighted. The future of pesticides in the environment is conditioned by their behavior in soils. The interaction between various processes governing their future (retention, degradation, transfer) will determine, among others, their persistence (or remanence). In particular, pesticide degradation processes help to reduce this persistence. The potential of microbial biodegradation depends on the molecules (intrinsic toxicity, soil adsorption capacity), soil and climate factors (type of clays, organic matter, temperature and humidity), microbial factors such as global biomass and the presence of microorganisms adapted to certain molecules (isoproturon, 2,4-D) and historical treatments (frequency of treatment). In general, low input systems seem to favor soil microbial activity in comparison conventional systems.