SOERE PRO - Reunion has been initiated in 2013

The objective of SOERE PRO Reunion experimental device is to characterize the agronomic value and environmental impacts of sludge, composted sludge, pig manure and poultry litter.

Figure : Device implementation, with sugarcanne plantation; Manure amendement (UR R&R, Feder, 2014).

• Location: Reunion island, La Mare
• Administrator unit : UR Recycling and Risks, CIRAD (http://ur-recyclage-risque.cirad.fr/)
• Supervisor and contact: Feder Frédéric (Cirad) (http://agents.cirad.fr/index.php/Frederic+FEDER/General_info_EN)
• Number of treatments: 6 treatments (5 replicates)
• Plot size: ≈ 180 m²
• Surface SHON and nature : 1.2 ha

Treatments

The 1.1 ha is divided in 30 plots of 180 m² each. It contains 5 blocks of replicates, and each block corresponds to a randomized repetition of the following treatments:

1) Sewage sludge (digested, dried and limed sludge), with application every year (BA)

2) Compost of sewage sludge (digested, dried and limed sludge) with green waste, application every 3 or 4 years (CB)

3) Poultry manure, with application every 4 years (LV)

4) Pig slurry (LP)

5) Mineral fertilization (T).

Four plots (RMFC1, RMFC3, RMFC4 and RMFC5) are fertilized as the mineral fertilized control plot, 3 out of 4 years and were alternatively used as control plot without fertilization 1 year out of 4. The doses of each OWP applied respect the balance of optimal fertilization; a complementation with mineral fertilizer is usually needed. To assess the impact of sugarcane cultivation, one plot is maintained in bare soil and received on a small surface the 4 organic treatments (SS-BS, CSS-BS, PS-BS and PM-BS) and a control (MFC-BS).

Figure : Plan of the SOERE PRO - Reunion experimental device (Feder)

Site management

The field is cultivated with sugarcanne.

Site instrumentation and monitoring

The site is equipped with a complete weather station and a sonic anemometer. All modalities of block 2 are equipped with the following automatic sensors every 20 cm deep: humidity, temperature, electrical conductivity are measured using TDR CS 650 probes ; tension of water on UMS T4e tensiometers. All instruments are connected to a Campbell CR1000 Datalogger and measures are saved every minutes.

All the modalities of the block 2 are equipped with a meter lysimetric glass fiber; leachates are collected in the glass flasks in manholes and are regularly sampled for analysis.

Greenhouse gas emissions are measured by automatic measuring chambers connected to CO₂ and N₂O analyzers. Twelve speakers are placed on different modalities with always three repetitions. The volatilization of NH₃ is also monitored for 3 months after spraying.

Figure : Monitoring instrumentations of soil climat on the SOERE PRO - Reunion (TDR probes on the bottom left ; soil climat equipments profile) (UR R&R, Feder, 2014)

Pedo-climatic context

The tropical island of Reunion is located in the Indian Ocean, 700 km east of Madagascar. Our study site is located in the Cirad research station of La Mare (60 m above sea level). Annual rainfall is 1800 mm/year and average temperatures are 24°C. Annual hydric deficit for the sugarcane, the dominant culture in this area, is in average 800 mm/year for an expected yield of 120 T/ha of harvested sugarcane. The soils have developed over volcanic rocks (olivine basalts, series of oceanites over 340,000 years BP). They are generally deeper than 1 m and well-drained with a strongly developed polyhedric structure. Its mineralogy is dominated by kaolinite and iron and aluminium oxides. This soil is a Nitisol (IUSS Working Group WRB, 2015) on the base of description and diagnostic criteria.

Partners

SOERE PRO - Reunion is managed with a partnership CIRAD, Veolia Eau, DP SIAMM and European funds FEADER.

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