Effects of water management and cultivar on carbon dynamics, plant productivity and biomass allocation in European rice systems

Abstract

Water saving techniques, such as alternate wetting and drying (AWD), are becoming a necessity in modern rice farming because of climate change mitigation and growing water use scarcity. Reducing water can vastly reduce methane (CH 4 ) emissions; however, this net climate benefit may be offset by enhanced carbon dioxide (CO 2 ) emissions from soil. The main aims of this study were: to determine the effects of AWD on yield and ecosystem C dynamics, and to establish the underlying mechanistic basis for observed trends in net ecosystem C gain or loss in an Italian rice paddy. We investigated the effects of conventional water management (i.e. conventionally flooded paddy; CF) and AWD on biomass accumulation (aboveground, belowground, grain), key ecosystem C fluxes (net ecosystem exchange (NEE), net primary productivity (NPP), gross primary productivity (GPP), ecosystem respiration (ER), autotrophic respiration (RA), heterotrophic respiration (RH)), and soil organic matter (SOM) decay for four common commercial European rice cultivars. The most significant finding was that neither treatment nor cultivar affected NEE, GPP, ER or SOM decomposition. RA was the dominant contributor to ER for both CF and AWD treatments. Cultivar and treatment affected the total biomass of the rice plants; specifically, with greater root production in CF compared to AWD. Importantly, there was no effect of treatment on the overall yield for any cultivar. Possibly, the wetting-drying cycles may have been insufficient to allow substantial soil C metabolism or there was a lack of labile substrate in the soil. These results imply that AWD systems may not be at risk of enhancing soil C loss, making it a viable solution for climate change mitigation and water conservation. Although more studies are needed, the initial outlook for AWD in Europe is positive; with no net loss of soil C from SOM decomposition, whilst also maintaining yield.

Effects of Different Water Management and Fertilizer Applications on CO2 Fluxes from a Selected Myanmar Rice (Oryza sativa L.) Cultivar

“…However, reported data from intermittently flooded systems showed more positive values of the CO 2 fluxes [7,47,56]. These finding suggest that slightly effects on total CO 2 fluxes by water management practices, but were more affected by the specific growth stages of the plant development and soil temperature [57].…”

Biochar with Alternate Wetting and Drying Irrigation: A Potential Technique for Paddy Soil Management

“…Compared to continuous flooding irrigation, AWD provides more oxidizing conditions in the soil. This phenomenon may stimulate the decomposition of plant residue and organic matter in the soil, especially in rice's vegetative growth stage [46]. This instance may generate increased CO 2 emissions from the soil by decaying organic matter and declining organic matter status in soil [47].…”

Effect of water management on microbial diversity and composition in an Italian rice field system

“…The field site was located at the CREA—Research Centre for Cereal and Industrial Crops in Vercelli, Italy (45°19'21.96'' N, 8°22'24.07'' E). More detailed information on soil characteristics and climate is described in Oliver et al ( 2019 ) and Monaco et al ( 2021 ). The experiment was set up in 2015 and consisted of four replicated field blocks, each block contained one site under continuously flooded water management (CF) and one site under AWD management (Fig.…”

“…However, more research is needed to demonstrate whether this strategy is generally applicable, and if it provides a viable alternative in all geographical regions. Studies evaluating AWD managements in European rice agriculture for instance are still limited to date (Oliver et al 2019 , Monaco et al 2021 ).…”