French research "OR observatory" - Site design and monitoring

The evolution of the agro-systems submitted to repeated inputs of Organic residues (OR) are measured, at the scale of the field plot. The effects of various OR are tested:  urban and agricultural OR (sludges, composts, farmyard manures), various treatment processes (no treatment, composting, anaerobic digestion).

The monitoring which is done on the experimental devices allows to evaluate the evolution of the compartments of the agro-system subjected to repeated OR spreading (soil, OWP, plants, water, air), with respect to local agricultural management practices en environmental context. 

Site design and instrumentation

All on-going instrumented sites are analytical sites including replicated blocks with the different treatments (see "Experimental devices". Individual plots go from 100 to 500 m2. All sites are instrumented with a meteorological weather station to collect general climatic data.

In the 5 on-going sites (QualiAgro, PROspective, EFELE, SOERE PRO-Réunion, SOERE PRO-Sénégal), one block of treatments is instrumented:

• To measure soil climatic conditions: T° (thermistance), water contents (TDR), water potential (tensiometers)
• To collect soil water solutions at different depths
• To measure greenhouse gas emission (GHG) in some of the treatments (automatic chambers and measurement of CO₂ and N₂O)

Figure: Soil instrumentation for climatic data measurement and soil water collection

GHG emissions are continuously measured at least in 2 treatments in the 4 on-going sites QualiAgro, PROspective, EFELE and SOEREPRO-Réunion. In these sites, other gas emissions are punctually measured during specific campaigns: NH₃ volatilization after OR application, Volatic organic compounds (VOC).

Figure: Automatic chambers for greenhouse gas emission (GHG) measurements (Morvan)

Site management and sampling

All sites are cropped and have their own technical management (applied OR, frequency of application, crop successions… The climatic data are continuously collected.

Regular samplings of the different matrices studied are realized for analysis:

• Soils before each OR application including before the first application in each plot for chemical characteristics in the ploughed horizon, every 4 to 6 years in the deeper horizons
• Soils in the upper horizons for biological indicators in spring
• Plants (grains and residues) every year and in each plot for yield and chemical characteristics
• Soil solutions in lysimeters (5 to 10 times each draining period) for volumes and chemical characteristics
• Organic Residues at each application. The rate of OR application is controlled. The physico-chemical characteristics are measured.

Samples management and analyses

The applied organic residues (OR), soils, crops and waters (rains and leached waters) are sampled and prepared in respect to the French and international standards. Samples of OR, soil and crops are long-term stored under harmonized conditions to allow future analyses and/or investigations by scientists.

The same analyses (parameters, analytical methods, laboratories) are done on samples for the 5 on-going sites (see table).

Table: Main data monitoring done in the 5 on-going sites of the SOERE PRO (QualiAgro, EFELE, PROspective, La Réunion)

Data management

Data management is centralized at the French OR Observatory network level with an Information System (IS) devoted to OR datasets: https://si-pro.fr/

• web interfaces (data integration and extraction)
• data bases: metadata (pedoclimatic context, OR processes/composition), field experiment data sets, OR analytical data sets, field management data sets, samples management informations
• data sets: French OR Observatory network, devices managed by sector partnerships

The information system is developed by INRA computer engineers devoted to develop and manage the information systems of the INRA long-term observatories (INRA Orléans).

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