Long Term Paddy rice-upland rotational experiment: Uruguay Silvana Tarlera 3rd Meeting PRRG Stuttgart, AR

Mean temperature Sept-Apr: 19. 2ºC BACKGROUND - Uruguay Rice 32° S; 53° W Mean temperature Sept-Apr: 19. 2ºC Annual Rainfall: 1361 mm Area: 160500 ha Rice Yield: 8000-8500 kg ha-1 Research Station INIA- Treinta y Tres 160487 2015-2016; 194584 2010-2011, rainfall evenly distributed throughout the year, media temp summer 21,9; winter 11,9 Satellite images Jan-Feb 2016

Oxic upland conditions are rotated with seasonally anoxic wetland conditions. Fallow season (cuando no hay arroz) Characteristics of the rice production system in Uruguay:Therefore 2/5 of the time during the crop cycle, the soil stays in non-flooded conditions. Starter fertilizers are normally applied at seeding and mainly consist in N and P applications. Additionally farmers also apply one to two urea top-dressings, at tillering and panicle iniciation. Total applied N amounts are consistently lower (average 60-70 kg N ha-1) when compared with major rice production regions The rice sector has consistentely exported 90% of the total production. At the beginning of the 90`s the cuntry changed from producing almost exclusively tropical Japonica long-grain rice (SouthernUSA type to the current situation, with 86%of the production with ilocally developed ndica varieties following the increase demand of Brazil that is yhe main market. The adoptation of technology has allowed an increase in the average yield of the country at a constant rate during the last 40 years, achieving a record of 8 ton /ha ib 2006. The technologies which are worth to mention, besides the adpotion of high yielding varieties, are: soil management practices which allow sowing of a higher percentage of area in optimum period, including gliphosate application and tillage reduction, early weed control and irrigation, as well as efficient management of fertilizers and chemicals Is the major irrigated crop Is grown in variable rotations One crop per year between october and march Highly mecanized Seeded into dry soil, depending on rainfall occurrance flushing is required before permanent flood 30 days after seeding. Non-floofded preseason of more than 180 days N,P. K8In some casesbapplied at plantring, 1 or 2 N top dressings (tillering/panicle initiation , straw incorporation?without OM application. Rice crop in Uruguay shares the use of soils with cattle production. Rice production rotates with 3 to 4 years of pastures before one or two years of rice. Most frequent pasture species planted in rotation with rice are Lotus (Lotus corniculatus L.), white clover (Trifolium repens L.) and ryegrass (Lolium multiflorum). Nitrogen fixation is expected to occur during the pasture period. This production system is highly sustainable, with only minimal requirements of herbicide, fungicide, insecticide and fertilizer. Paddocks are grown with rice in rotation with improved pastures (white clover, red clover, lotus and ryegrass are oversown by plane after harvest in 55-60% of the rice seeded area ) No till planting of forage species are recommended to increase beef production during the period without rice (3/4 years). Grasses and legumes presence improve soil conditions, which has big impact on the next crop One or two N top dressings are normally used (tillering /panicle initiation). The first top dressing is applied on dry soil 1-2 days before flooding to prevent N losses; the second one is applied, when the soil is flooded.

Traditional rice production system Year 1 2 3 4 5 6 Treatment SS AW T. Control Rice1 Pa Rice2 Impr Pa   Each plot measures 18 by 60 m, 60 plots, repeated 3 times in the location and all phases are present at the same time. Ongoing long term experiment randomized complete block design with three replications SS: spring- summer; AW: autumn-winter

Previous studies on GHG emissions Irisarri, P., Pereyra, V., Fernández, A., Terra, J., Tarlera, S. e Irisarri, P., Pereyra, V., Fernández, A., Terra, J., Tarlera 2012

Previous studies on GHG emissions

Long-term paddy rice-upland rotation experiment Year 1 2 3 4 5 6 Treatment SS AW Rice Pa   Rice1 Soybean Rice2 Sorghum Impr Pa Soybean1 Soybean2 Each plot measures 18 by 60 m, 60 plots, repeated 3 times in the location and all phases are present at the same time. Ongoing long term experiment randomized complete block design with three replications SS: spring- summer; AW: autumn-winter

Long-term paddy rice-upland rotational experiment General Goal: Identify systems of intensification of soil use by paddy rice-upland crop and pastures rotations that are economically and physically sustainable.

Benefits of rotational plots in paddy rice Multiple use of the land Improvement of nutrient imbalance in the plant and soil Increase in crop production Mitigation of methane emission Cuantify : Diseases in rice plants, weeds, Organic C, mineralization potential, economic and physical productivity

Long-term paddy rice-upland rotational experiment General Goal: Identify systems of intensification of soil use by paddy rice-upland crop and pastures rotations that are economically and physically sustainable. Specific goal: Characterize these systems in relation to GHG emissions and the soil-microbial dynamics involved. Structure and function of the methanogenic microbial communities in Uruguayan soils shifted between pasture and irrigated rice fields. Fernández Scavino et al.; Environmental Microbiology, 2013.

Long-term paddy rice-upland rotation experiment Year 1 2 3 4 5 6 ROTATION SS AW Rice Pa   Rice1 Rice2 Impr Pa Soybean

Long-term paddy rice-upland rotational experiment: Interactions among GHG emissions ,microbial dynamics and past soil management Physicochemical parameters of the soil: pH, redox potential, NO3 - , NH4 + , Org C Potential microbial activities: nitrifying, denitrifying, methanogenic and methanotrophic in the lab Quantitative PCR of key genes: nirK, nirS, nosZ, amoA, amoB, pmoA and mcrA Gas fluxes with the closed chamber method in the field on an annual basis Mencionar annual basis as opposed to seasonal, monitor emissions year-round, comentar que nada de metano pero si N2O El promedio es 1,42% de Corg para los primeros 15 cm de suelo al inicio del exp , IMP de medir DOC, dissolved organic C A nosotros nos dio R1 1,53 R4 1,75 R6 1,57 pH 5,8 promedio Planosol, sand, silt, clay: 37,40,23%

Soil CH4 flux at different rice growth stages Similar pattern of emission with peak at flowering

Tillering stage a a a ab b a If upland plots year before, less methane emission

Long-term paddy rice-upland rotation experiment Year 1 2 3 4 5 6 ROTATION SS AW Rice Pa   Rice1 Rice2 Impr Pa Soybean

Tillering stage a a a ab b a If upland plots year before, less methane emission

Flowering stage CH4 Flux

No significant differences observed Flowering stage CH4 Flux No significant differences observed

Biplot of Principal Component Analysis of the variables studied at the tillering stage

Long-term paddy rice-upland rotation experiment Year 1 2 3 4 5 6 ROTATION SS AW Rice Pa   Rice1 Rice2 Impr Pa Soybean

Long-term paddy rice-upland rotational experiment: Interactions among GHG emissions ,microbial dynamics and past management Daniela Oreggioni Andrea Martínez Lucía Ferrando Ana Fernández Silvana Tarlera Pilar Irisarri Gabriela Illarze Lucía Salvo Irma Furtado Matías Oxley Ignacio Macedo José Terra

3rd Meeting PRRG Stuttgart, AR Thank You! 3rd Meeting PRRG Stuttgart, AR