Effects of massive organic matter amendment, irrigation, and grass cover on the plant soil continuum in viticulture
Flor Regus, Isabelle Laffont-Schwob, Lisa Foli, Dupuy Nathalie, Pascale Prudent, Rayhane Hamrouni, Anne-Marie Farnet Da Silva IMBE, LPED, LCE, FRANCE
The current effects of climate changes are being felt throughout the world and vary with the geographical location. For instance, many regions already struggle with water availability and soil erosion. In the Mediterranean region, more frequent and more severe droughts already occur, which have both environmental and socioeconomic issues. These drastic climate conditions are troublesome for agriculture in the Mediterranean, where soils are particularly poor in organic matter and weakly developed. In Southeastern France, viticulture is of great social, cultural, and economic importance and the additional pressure of climate change is challenging for the winegrowers.
Consequently, sustainability and long-term decisions to safeguard wine growing’s future is a priority for this socio-economic sector and agricultural techniques are being adapted to the current climatic scenario. The focus of this experiment is to evaluate the effect that three different practices, massive amendment (MA), irrigation and grass cover, have on the plant soil continuum in vineyards in a Mediterranean context. The main objectives are to evaluate: (i) the relative effects of irrigation, grass cover and massive organic amendments and their interactions on the plant soil continuum, (ii) the seasonal effects of these practices in interaction or not and more precisely how these practices may help the plant soil continuum to cope with the severe drought conditions. To achieve these objectives, 4 field campaigns have been done over one year in the vineyards from the Association Viticole de la St.Victoire (Bouches-du-Rhône, Southeastern France). Sixteen different parcels were sampled, according to four different modalities and considering grass cover in each parcel: control, massive amendment, irrigation, massive amendment + irrigation. For the four field campaigns, we evaluated: plant leaf phytometabolites using infrared spectroscopy and fluorimetry, soil physico-chemical parameters (pH, EC, density, water holding capacity, total C and N, organic matter quality using infra-red spectroscopy, pseudo-total and potentially bioavailable Cu) and soil microbial properties (microbial respiration, microbial biomass, catabolic diversity using BIOLOG plates of bacterial and fungal communities). Preliminary results show significant positive effects on basal respiration of organic matter in June and grass cover in August. Similarly, different catabolic diversity structures were observed in the presence of organic matter in June and with grass cover in August. The effect of organic matter addition in autumn is still observable in June. Moreover, our study reveals grass cover allowed microbial communities to cope with drastic summer climate conditions by sustaining microbial respiration via a particular catabolic diversity structure.
Hello everyone um thank you for having me my name is florus and I am a third year student at the imbe and the lped so today I will present some of the results that I have from one of my um experiments um called effects of massive organic Amendment irrigation and grass
Cover on the uh plant soil continuum btic culture um I just want to also say that my PhD is financed by The itm Institute under the ALCO project so um just a little bit really quick about what the ALCO project is it stands for agriculture bio control bio
Amendment and vulture and it is a multidisciplinary uh project that um the one of the goals is to find alternative solutions for the use of U uh of agrochemicals more importantly the use of pesticides so going back to the study that I am going to present um a little
Bit of the context as to why this is important so um we all know that the imminent changes of clim of climate change are here um that means for cter in the Southeast in southeast France that we’re going to have more frequent and more intense uh heat waves on top of
That in btic culture you have a lot of intensive practices just such as the use of tillage for to prepare the soil and the use of agrochemicals the thing is over time the use of these intensive practices deteriorate your soil and the biodiversity on the soil so because of that there is an
Urgent need to change agricultural practices and there is a need to also evaluate um this this new sustainable Alternatives so for this part of the study what we wanted to know was um if organic massive uh organic massive organic matter Amendment and the use of grass cover are
Beneficial practices for soil quality in the Mediterranean context especially in Vineyards so our hypothesis was that massive organic amendments and grass cover favor the living part of the soil we know from the literature that the use of massive organic Amendment increases soil nutrient availability benefits soil microbial biomass and mineralization of
Nutrients and on the other hand we know that the use of grass cover benefits nutrition cycling microbial activities increases so soil microb biomass and it also acts as a physical um barrier against the erosion of the soil so moving further for this particular study we partnered up with the
Associ and for this part of the study we did four field campaigns one in early June end of August December and Mars uh in March uh and for this study what we had were four modalities we had a control where there was no organic Amendment or
Grass cover we also had you know one with massive organic Amendment one with grass cover and one with both modalities and we had a total of 32 soil samples so um what we wanted to do in the overall study was to like I said study the effects in the soil plant uh
In the soil and plant ium so for that we looked at the so uh soil biomarkers we looked at the physical chemical physical chemical parameters such as granulometry conductivity copper content pH water PH KCl nutrient content um water holding capacity of or total organic carbon and for the biological we looked at the
Microbial activity such as respiration and biomass and also uh catabolic uh diversity use in biolog plates and we looked at the mcroof um in the in terms of the abundance of earthworms for the sake of this presentation I will only focus on the microbial uh
Results um on the other hand we also did looked at some plant uh markers we mostly looked at the uh phytometabolites using spect uh spectr photometry and also at the um um organic matter quality of the leaves so a little bit of my results so as I said um for the soil microbial
Respiration we looked at um uh we we are looking at the results from June and August for this presentation because those were to me what uh what had the most U striking interesting results so in the month of June we have that both uh there was a
Significant effect from or for the from the addition of micro of organic uh matter and U baso respiration they both resulted in U higher respiration rates however if you if we move to the mo month month of August there was only a significant effect from grass cover
Which as you can see here it was higher um well it was higher the respiration where there was grass cover than well without it um to sustain also this results we we did the soil catabolic structure for both bacteria and fungi and here is is
Just the results of a PCA for the soil catabolic structure of bacteria um as you can see in the month of June there is a difference between my control treatments and all other treatment mod modalities and then moving forward in the month of August there is a difference between both modalities
Meaning the organic matter and grass cover versus um all my other treatments so the similar results um are for the catabolic stru structure for fungi um where in the month of June um the control is U different than all of my other um treatment modalities and
However here in August we have that the the main driver in the differences is the grass cover so to conclude in the month of June we see an effect of organic matter uh we see a positive effect in myral res microbial respiration this is sustained by change in microbial catabolic
Structure and we also Al saw an increase in total uh nitrogen cont content in soil there was also a significant effect of grass cover uh where we saw positive effects on microbial respiration now when it comes to our results in June um there were I didn’t
Put um the the graph here but there was a significant increase when using grass cover in terms of water holding capacity um we saw as a positive effects on micro respiration and like um it’s this is sustained by change in microbial catabolic structure this could be due to
Like the aial part of the plants being you know dead and decomposed so overall we saw in this study that the application of organic Amendment and grass cover have a positive influence in soil microbial activities we see that grass cover and organ and organic Amendment help the soil maintain its functionality during
Drought season meaning June and August versus those in December and March um also an interesting result is that the effect of organic matter is still observable more than six month six months after the application um so overall in this case study in this case study the use of sustainable practices was overall
Beneficial for soil micro for so soil microbial communities thank [Applause] you