Pore-scale monitoring of the effect of microarchitecture on fungal growth in a two-dimensional soil-like micromodel

In spite of the very significant role that fungi are called to play in agricultural production and climate change over the next two decades, very little is known at this point about the parameters that control the spread of fungal hyphae in the pore space of soils. Monitoring of this process in 3 dimensions is not technically feasible at the moment. The use of transparent micromodels simulating the internal geometry of real soils affords an opportunity to approach the problem in 2 dimensions, provided it is confirmed that fungi would actually want to propagate in such artificial systems. In this context, the key objectives of the research described in this article are to ascertain, first, that the fungus Rhizoctonia solani can indeed grow in a micromodel of a sandy loam soil, and, second, to identify and analyze in detail the pattern by which it spreads in the tortuous pores of the micromodel. Experimental observations show that hyphae penetrate easily inside the micromodel, where they bend frequently to adapt to the confinement to which they are subjected, and branch at irregular intervals, unlike in current computer models of the growth of hyphae, which tend to describe them as series of straight tubular segments. A portion of the time, hyphae in the micromodels also exhibit thigmotropism, i.e., tend to follow solid surfaces closely. Sub-apical branching, which in unconfined situations seems to be controlled by the fungus, appears to be closely connected with the bending of the hyphae, resulting from their interactions with surfaces. These different observations not only indicate different directions to follow to modify current mesoscopic models of fungal growth, so they can apply to soils, but they also suggest a wealth of further experiments using the same set-up, involving for example competing fungal hyphae, or the coexistence of fungi and bacteria in the same pore space

Effects of repeated organic amendment applications on soil and crop qualities

WOS:000392711300011Soil application of organic waste products (OWP) favors the increase of soil organic matter (SOM) and biological activity, the recycling of nutrients and crop production, but it may also lead to soil contamination. All these effects may occur simultaneously and must be considered in the evaluation of the practice. Various urban composts and manure have been applied every second year in a long-term field experiment during 15 years. A soil sampling assessing the cumulative residual effects of seven applications was used to compare the impact on soil and crop quality of four OWP: a municipal solid waste compost (MSW), a co-compost of sewage sludge and green waste (GWS), a biowaste compost (BIO) and a farmyard manure (FYM). More than 100 different soil indicators were measured (including organic C, N availability, pH, POlsen, plasticity, microbial biomass, enzymatic activity, trace elements and crop yield) and classified in categories to explain soil functioning including crop production: soil fertility, soil biological activity, soil biodiversity, soil physical stability, soil sanitary status (available and total) and crop productivity. Based on these categories, seven minimum data sets (MDS) were defined using statistical analysis, in order to eliminate overlapping parameters and select significant indicators highlighting the effects of OWP compared with a mineral fertilization. The aim of this study was to evaluate the long-term effects of repeated OWP applications on the seven categories of indicators. The OWP were characterized by different qualities and properties of organic matter (OM), which drove their potential effects after application on cropped soils. The GWS and BIO were the most efficient OWP at increasing SOM content, which was one of the major drivers of the effects

Metametha dataset

Comparison of N fluxes (N20, NH3, NO3 …) between 5 fertilization managements : livestock effluents, digestates and mineral nitrogen. This dataset was collected in part of Metametha project, funded by ADEME. During three years (2017,2019 and 2019) measurements were made in soil, water and air, at wheat and rapessed plots fertilized with slurry cattle, manure cattle, raw digestates, solid and liquid treated digestates and mineral nitrogen. (2019-12-12

Prise en compte des propriétés des sols pour expliquer les transferts de trois pesticides

poster abstractPrise en compte des propriétés des sols pour expliquer les transferts de trois pesticides. 45e Congrès du Groupe Français des Pesticides Devenir et impact des pesticides : verrous à lever et nouveaux enjeux. 45e Congrès du Groupe Français des Pesticide

Fate of glyphosate and degradates in cover crop residues and underlying soil: A laboratory study

The increasing use of cover crops (CC) may lead to an increase in glyphosate application for their destruction.Sorption and degradation of 14C-glyphosate on and within 4 decaying CC-amended soils were compared to itsfate in a bare soil. 14C-Glyphosate and its metabolites distribution between mineralized, water-soluble,NH4OH-soluble and non-extractable fractions was determined at 5 dates during a 20 °C/84-d period. Thepresence of CC extends 14C-glyphosate degradation half-life from 7 to 28 days depending on the CC. 14C Glyphosate dissipation occurred mainly through mineralization in soils and through mineralization and boundresidue formation in decaying CC. Differences in sorption and degradation levels were attributed to differencesin composition and availability to microorganisms. CC- and soil-specific dissipation patterns were establishedwith the help of explicit relationships between extractability and microbial activity