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A 2-year field experiment was conducted to analyse the effects of fresh and aged biochar on soil properties, as well as herbicide effectiveness and rice-yield components in a Mediterranean environment. Six managements were used: no-tillage and sprinkler irrigation either without (NoT) or with first-year biochar application (NoTB), conventional tillage and sprinkler irrigation either without (ConvT) or with first-year biochar application (ConvTB), conventional tillage and flooding irrigation either without (ConvTF) or with first-year biochar application (ConvTFB). The measurements done in the first (2018) and second (2019) years after biochar addition were taken to determine its fresh and aged effects, respectively. The application of biochar led to an improvement of the soil properties such as increase in the soil's organic carbon content, pH, and dehydrogenase activity. It also reduced weed pressure, regardless of the management used, and sprinkler systems were found to have the greatest herbicide effectiveness, especially in ConvT and ConvTB. In terms of production, there were significant increases in yield with the application of fresh biochar, in the amended managements under tillage compared with their unamended counterparts. The greatest yields were found under ConvT and ConvTB, with mean values for both treatments of 10,770 and 11,299 kg ha−1 in the fresh and aged years, respectively. Furthermore, water productivity reached its greatest values when sprinkler was used, especially with tillage for which the application of fresh biochar increased water productivity by a factor of 1.09 relative to ConvT. Therefore, sprinkler irrigation in combination with tillage and biochar applications can be regarded as an efficient alternative to flooding irrigation in order to ensure productive viability of rice in water-stressed regions.

Olive orchards cover over 10 million hectares worldwide, with production techniques undergoing significant changes in the past three decades. The traditional rainfed approach, involving minimal inputs, has given way to irrigated super-intensive systems with higher planting density, increased productivity, a greater use of fertilizers and phytopharmaceuticals, and total mechanization. Its impact on soil chemical properties remains a topic of great debate, and no definitive consensus has been reached. Our main objective was to examine the different effects of traditional olive orchards and super-intensive orchards on soil chemistry over a decade. We collected and analyzed 1500 soil samples from an irrigation perimeter in southern Portugal in 2003 and 2013. Our findings indicate that, compared to traditional olive orchards, super-intensive ones show, in a decade, a significant decrease in soil organic matter (less 22.8%—p < 0.001), namely due to the increase in mineralization caused by an increase in soil moisture content as a result of irrigation practice, and an increase in sodization (more 33.8% of Ext Na—p < 0.001) highlighting the importance of monitoring this factor for soil fertility. In comparison to other irrigated crops in the region, super-intensive olive orchards promote a significant soil acidification (from 7.12 to 6.58), whereas the pH values of the other crops increase significantly (3.3%, 13.5%, and 3.0% more in corn, tomato, and cereals, respectively). Mainly because of the decrease in organic matter levels with soil acidification and soil sodization, we can underline that hedgerow olive orchards can affect soil characteristics negatively when compared with traditional ones, and it is necessary to adopt urgent measures to counter this fact, namely sustainable agriculture practices.

The sustainable management of Mediterranean agricultural soils, characterized by salinization and low organic matter content, requires a thorough understanding of their temporal and spatial evolution. The focal point of this investigation encompasses an area of 6769 ha within the Portuguese Mediterranean basin, from which as many as 686 topsoil specimens were acquired during the periods 2001/2002 and 2011/2012 for the purpose of scrutinizing soil organic matter (SOM) content, pH measured in water, and electrical conductivity (EC). The methodology employed both classical and geostatistical techniques, and the terrestrial samples were classified in accordance with the irrigation mechanisms in use (namely, drip and sprinkler systems), subsequently juxtaposed with their counterparts in rainfed systems. Predictive maps were generated using the Ordinary Kriging algorithm for spatial interpolation. The findings demonstrate that irrigated Fluvisols displayed lower SOM content compared to rainfed soils, with sprinkler-irrigated soils experiencing a 16.1% decrease and drip-irrigated soils showing a more pronounced 26.6% decrease. Moreover, drip-irrigated soils contained 12.5% less SOM compared to sprinkler-irrigated soils. The pH levels stabilized at around 6.6 in both rainfed and irrigated soils, with no significant differences observed between the irrigation methods. Furthermore, irrigated Fluvisols exhibited higher EC values compared to rainfed soils, with both sprinkler and drip-irrigated soils showing values that were 35.2% higher. These results underscore the impact of irrigation practices on soil properties, including elevated EC values due to increased soil salt accumulation. The study highlights the necessity of considering specific irrigation systems and associated practices to ensure sustainable soil health and productivity. Adopting management approaches that account for these factors is crucial for preserving optimal soil conditions in Mediterranean agricultural systems.

Traditional rice (Oryza sativa L.) management (tillage and flooding) is unsustainable due to soil degradation and the large amount of irrigation water used, an issue which is exacerbated in the Mediterranean region. Therefore, there is a need to explore rice management strategies in order to improve water-use efficiency and ensure its sustainability. Thus, field experiments were conducted to determine the medium-term effects of different irrigation and tillage methods combined with a single compost application on water and rice productivity, as well as food safety in a semiarid Mediterranean region. The management systems evaluated were: sprinkler irrigation in combination with no-tillage (SNT), sprinkler irrigation in combination with conventional tillage (ST), which were implemented in 2015, and flooding irrigation in combination with conventional tillage (FT), and their homologues (SNT-C, ST-C, and FT-C) with single compost application in 2015. In reference to rice grain yield, the highest values were observed under ST treatment with 10 307 and 11 625 kg ha−1 in 2018 and 2019 respectively; whereas between FT and SNT there were no significant differences, with 8 140 kg ha−1 as mean value through the study. Nevertheless, sprinkler irrigation allowed saving 55% of the total amount of water applied in reference to flooding irrigation. Furthermore, the highest arsenic concentration in grains was found under FT but it decreased with compost application (FT-C) and especially with sprinkler irrigation, regardless of tillage management systems. However, sprinkler irrigation favors the cadmium uptake by plants, although this process was reduced under SNT in reference to ST, and especially under amended compost treatments. Therefore, our results suggested that a combination of sprinkler irrigation and compost application, regardless of the tillage system, could be an excellent strategy for rice management for the Mediterranean environment in terms of water and crop productivity as well as food safety.

Traditional rice (Oryza sativa L.) production by flooding is a source of greenhouse gases (GHG), especially methane. The high consumption of water, as well as the chemical and physical degradation caused by these traditional practices in rice soils, is promoting a decrease in rice production in the Mediterranean area. The aim of this study was to monitor GHG emissions and the net ecosystem carbon balance (NECB) from rice produced with sprinkler irrigation techniques and also assess the impact of olive mill waste compost (C-OW) application and tillage on GHG emissions and the NECB. A field experiment for irrigated rice production was implemented by considering four different treatments: (1) tillage (T); (2) no tillage—direct seeding techniques (DS); (3) application of C-OW followed by tillage (TC); and (4) application of C-OW followed by direct seeding (DSC). The C-OW was only applied in the first year at a dose of 80 Mg ha−1. GHG emissions were monitored over three years in these four treatments in order to estimate the direct (first year) and residual (third year) effects of such practices. The application of C-OW caused an increase of 1.85 times the emission of CO2-C in the TC-DSC compared to the T-DS in the first year. It is noteworthy that the TC treatment was the only one that maintained an emission of CO2-C that was 42% higher than T in the third year. Regardless of the treatments and year of the study, negative values for the cumulative CH4 were found, suggesting that under sprinkler irrigation, CH4 oxidation was the dominant process. A decrease in N2O emissions was observed under direct seeding relative to the tillage treatments, although without significant differences. Tillage resulted in an increase in the global warming potential (GWP) of up to 31% with respect to direct seeding management in the third year, as a consequence of the greater carbon oxidation caused by intensive tillage. DS presented a positive NECB in the accumulation of C in the soil; therefore, it provided a greater ecological benefit to the environment. Thus, under Mediterranean conditions, rice production through a sprinkler irrigation system in combination with direct seeding techniques may be a sustainable alternative for rice crops, reducing their GWP and resulting in a lower carbon footprint. However, the use of C-OW as an organic amendment could increase the GHG emissions from rice fields irrigated by sprinklers, especially under tillage conditions.

The olive oil industry produces high amounts of waste, which need to be valorized in a more sustainable way as an alternative to its traditional use as an energy source, with high associated CO2 emissions. Rice (Oryza sativa L.) is one of the most important crops for global food security; however, the traditional cropping systems under flooding lead to an important decrease of soil quality, as well as relevant emissions of greenhouse gases (GHG). The aim of this study was to assess the GHG emission from rice fields amended with composted two-phase olive mill waste (C-TPOW), in Mediterranean conditions. A field experiment was carried in rice cultivated by the traditional system, either unamended (Control) or amended with C-TPOW (Compost). GHG emissions were measured over three years following a single C-TPOW application (80 Mg ha−1 only in the first year of study), so that the results found in the first and third years correspond to its direct and residual effects, respectively. Compost decreased CO2 emissions relative to Control by 13% and 20% in the first and third year after C-TPOW application, respectively. However, in the case of CH4 and N2O, increases in the total cumulative emission were recorded in Compost relative to Control throughout the study, in agreement with the highest β-glucosidase and urease activity observed in the amended soil. The values of global warming potential (GWP) and yield-scaled GWP increased by 14% and 11%, respectively, in Compost relative to Control in the first year, but no significant differences between treatments were observed three years after application for GWP and yield-scaled GWP. Therefore, the use of C-TPOW as soil amendment in rice fields could be a good option since its impact on GHG emissions seems to decrease over time, while the benefit for soil remained clear even after 3 years.

The practices (tillage and flooding) used for rice crops are unsustainable, especially in areas characterized by water shortages, such as the Mediterranean region. Therefore, it is necessary to develop sustainable methods in order to ensure the viability of rice production. However, it is essential to understand the effects that alternative management can have on herbicide behavior. In this context, this paper describes the first field experiment conducted to evaluate the medium-term effects of different agricultural practices on the fate of bispyribac sodium (BPS). Thus, the treatments were as follows: tillage and flooding (TF), tillage and sprinkler (TS), and no-tillage and sprinkler (NTS). In addition, "alperujo" compost (AC) from olive mill waste was used in each treatment (TF-AC, TS-AC, and NTS-AC). The AC was applied only once in 2015 when the TS and NTS treatments were implemented. The AC amendment increased the adsorption of BPS and its irreversibility, thereby decreasing the BPS leaching capacity. Furthermore, throughout this study, the BPS persistence was up to 1.85 times greater with sprinklers than in the flooding condition, which could explain the high values of BPS effectiveness (increased by a factor of 1.45 on average) found with sprinklers. Therefore, the implementation of sprinklers in combination with AC can be considered a sustainable strategy for Mediterranean rice production, at least in the medium term, as it reduces BPS water pollution and increases its weed control efficiency. [ABSTRACT FROM AUTHOR]

There is a small sample of edaphic geochemistry studies over large geographic areas, especially studies that consider major reference soil groups (RSG) that evaluate both native concentrations of elements and anthropogenically contaminated soils in agricultural settings, considering the long-term effect of agricultural practices on landscape sustainability. In this study, four RSGs were analyzed for the available trace elements Ni, Cr, Cd, Pb, Cu, Mn, and Zn, including other edaphic properties from 2002 to 2012. The main objectives were to assess the range of concentrations of the selected elements in the four typical Mediterranean soils, Cambisols, Luvisols, Calcisols, and Fluvisols, with heavy anthropogenic input (HAI) and compare them to minimal anthropogenic input (MAI). For MAI, the background levels of Pb, Ni, Cd, and Cr were highest in Calcisols, differing from those of Cambisols, Luvisols, and Fluvisols (p < 0.01), Cu is highest both in Calcisols and Luvisols while Mn is higher in Cambisols and Fluvisols (p < 0.05). The background concentration of Zn was the same in all RSGs (p > 0.05). For HAI, the reference levels of Pb, Ni, Cd, Mn, and Cr were highest in the Calcisols, and Cu was high in all RSGs except Fluvisols, while Zn presented the lowest concentrations in the Luvisol RSG, with all these results considering a confidence interval of 95%. Predictive maps for the sampled elements, as well as the edaphic bioavailability, are provided. This environmental impact assessment suggests that the land use is departing from sustainable ecosystem service development and that territorial management practices, with conservation goals in mind, should be adopted.

Olive orchards cover over 10 million hectares worldwide, with production techniques undergoing significant changes in the past three decades. The traditional rainfed approach, involving minimal inputs, has given way to irrigated super-intensive systems with higher planting density, increased productivity, a greater use of fertilizers and phytopharmaceuticals, and total mechanization. Its impact on soil chemical properties remains a topic of great debate, and no definitive consensus has been reached. Our main objective was to examine the different effects of traditional olive orchards and super-intensive orchards on soil chemistry over a decade. We collected and analyzed 1500 soil samples from an irrigation perimeter in southern Portugal in 2003 and 2013. Our findings indicate that, compared to traditional olive orchards, super-intensive ones show, in a decade, a significant decrease in soil organic matter (less 22.8%—p < 0.001), namely due to the increase in mineralization caused by an increase in soil moisture content as a result of irrigation practice, and an increase in sodization (more 33.8% of Ext Na—p < 0.001) highlighting the importance of monitoring this factor for soil fertility. In comparison to other irrigated crops in the region, super-intensive olive orchards promote a significant soil acidification (from 7.12 to 6.58), whereas the pH values of the other crops increase significantly (3.3%, 13.5%, and 3.0% more in corn, tomato, and cereals, respectively). Mainly because of the decrease in organic matter levels with soil acidification and soil sodization, we can underline that hedgerow olive orchards can affect soil characteristics negatively when compared with traditional ones, and it is necessary to adopt urgent measures to counter this fact, namely sustainable agriculture practices. [ABSTRACT FROM AUTHOR]

The sustainable management of Mediterranean agricultural soils, characterized by salinization and low organic matter content, requires a thorough understanding of their temporal and spatial evolution. The focal point of this investigation encompasses an area of 6769 ha within the Portuguese Mediterranean basin, from which as many as 686 topsoil specimens were acquired during the periods 2001/2002 and 2011/2012 for the purpose of scrutinizing soil organic matter (SOM) content, pH measured in water, and electrical conductivity (EC). The methodology employed both classical and geostatistical techniques, and the terrestrial samples were classified in accordance with the irrigation mechanisms in use (namely, drip and sprinkler systems), subsequently juxtaposed with their counterparts in rainfed systems. Predictive maps were generated using the Ordinary Kriging algorithm for spatial interpolation. The findings demonstrate that irrigated Fluvisols displayed lower SOM content compared to rainfed soils, with sprinkler-irrigated soils experiencing a 16.1% decrease and drip-irrigated soils showing a more pronounced 26.6% decrease. Moreover, drip-irrigated soils contained 12.5% less SOM compared to sprinkler-irrigated soils. The pH levels stabilized at around 6.6 in both rainfed and irrigated soils, with no significant differences observed between the irrigation methods. Furthermore, irrigated Fluvisols exhibited higher EC values compared to rainfed soils, with both sprinkler and drip-irrigated soils showing values that were 35.2% higher. These results underscore the impact of irrigation practices on soil properties, including elevated EC values due to increased soil salt accumulation. The study highlights the necessity of considering specific irrigation systems and associated practices to ensure sustainable soil health and productivity. Adopting management approaches that account for these factors is crucial for preserving optimal soil conditions in Mediterranean agricultural systems. [ABSTRACT FROM AUTHOR]

A 2-year field experiment was conducted to analyse the effects of fresh and aged biochar on soil properties, as well as herbicide effectiveness and rice-yield components in a Mediterranean environment. Six managements were used: no-tillage and sprinkler irrigation either without (NoT) or with first-year biochar application (NoTB), conventional tillage and sprinkler irrigation either without (ConvT) or with first-year biochar application (ConvTB), conventional tillage and flooding irrigation either without (ConvTF) or with first-year biochar application (ConvTFB). The measurements done in the first (2018) and second (2019) years after biochar addition were taken to determine its fresh and aged effects, respectively. The application of biochar led to an improvement of the soil properties such as increase in the soil's organic carbon content, pH, and dehydrogenase activity. It also reduced weed pressure, regardless of the management used, and sprinkler systems were found to have the greatest herbicide effectiveness, especially in ConvT and ConvTB. In terms of production, there were significant increases in yield with the application of fresh biochar, in the amended managements under tillage compared with their unamended counterparts. The greatest yields were found under ConvT and ConvTB, with mean values for both treatments of 10,770 and 11,299 kg ha−1 in the fresh and aged years, respectively. Furthermore, water productivity reached its greatest values when sprinkler was used, especially with tillage for which the application of fresh biochar increased water productivity by a factor of 1.09 relative to ConvT. Therefore, sprinkler irrigation in combination with tillage and biochar applications can be regarded as an efficient alternative to flooding irrigation in order to ensure productive viability of rice in water-stressed regions. [ABSTRACT FROM AUTHOR]

La temperatura del suelo es un factor clave en el crecimiento del maíz, al ser un cultivo muy sensible a las variaciones de temperatura y tener unos márgenes óptimos bastante elevados de germinación de la semilla, de crecimiento de la plántula y de fructificación. La agricultura de conservación tiende a disminuir la temperatura del suelo, debido a los rastrojos que se dejan en superficie, en cuya descomposición juegan un papel fundamental los microorganismos del suelo, y al incremento de humedad asociado a este tipo de manejo. Para una gestión adecuada de los suelos bajo agricultura de conservación es recomendable el seguimiento y el estudio de la temperatura y de las poblaciones microbianas en la capa superficial del suelo. Por ello, el objetivo de este estudio ha sido realizar un estudio comparativo de las oscilaciones de temperatura en diferentes manejos de agricultura de conservación frente a las obtenidas con un manejo de laboreo convencional, y determinar cómo afectan estas variaciones de temperatura a las poblaciones microbianas asociadas a la rizosfera del cultivo. Para ello se han realizado experiencias de campo en cuatro manejos diferentes bajo un mismo suelo, localizados en subparcelas contiguas; uno de siembra directa (SD), dos de siembra directa con cobertura (SDC) con diferente antigüedad de implantación y un manejo de laboreo convencional (LC). Se ha realizado una medida exhaustiva de la temperatura del suelo durante tres años completos y un seguimiento de la evolución de las poblaciones microbianas. El análisis de los resultados permite concluir que se produce una disminución de la temperatura en SD y SDC respecto a LC durante todo el periodo de cultivo, con unas oscilaciones de temperatura menores para los manejos de agricultura de conservación durante todo el año. Además, se aprecia un incremento en las poblaciones microbianas asociadas a SD y SDC con respecto a LC, que indicarían la existencia de intervalos óptimos de temperatura para el crecimiento microbiano en los manejos de agricultura de conservación.The temperature of the soil is a key factor in the growth of the maize, a sensible culture to the temperature variations, with high optimal temperature for germination of the seed, growth of plant and fruition. The conservation agriculture tends to diminish the temperature of the soil, due to the stubbles that are left in surface, in whose decomposition the microorganisms of the soil play a fundamental role, and to the associated increase of humidity this type of management. For a suitable management of soils under conservation agriculture is recommendable the study of the temperature and the microbial populations in the surface horizon. For these reasons, the objective of this study has been to make a comparative study of the oscillations of temperature in different managements from agriculture of conservation as opposed to the obtained with a conventional management, and to determine how affect these variations of temperature to the microbial populations associated to the rhizosphere of the culture. Field experiences have been made in four different managements under a same soil, located in contiguous subparcels; one of direct seeding (DS), two of direct seeding with cover (DSC) with different antiquity from implantation and a conventional tillage (CT). It has been made an exhaustive measurement of the temperature of the soil during three years and a monitoring of the evolution of the microbial populations. The analysis of the results allows to conclude that during the period of culture takes place a diminution of the temperature in SD and SDC with respect to LC, with smaller oscillations of temperature for the conservation agriculture. In addition, an increase in the microbial populations associated to SD and SDC with respect to LC is observed, that would indicate the existence of optimal intervals of temperature for the microbial growth in the managements of conservation agriculture.

Tendo como principal objectivo a análise das alterações provocadas no complexo de troca do solo pela prática continuada do regadio, recolhemos, de forma georeferenciada, nos 12400 ha que constituem o Perímetro de Rega do Caia e áreas imediatamente adjacentes (situado nos Municípios de Elvas e Campo Maior, distrito de Portalegre, Portugal), 14280 amostras da camada superficial do solo (0-20 cm), as quais, depois de misturadas 10 a 10 de forma a que cada amostra compósita representasse 11,1 ha, foram analisadas no que respeita à composição do complexo de troca do solo e à capacidade de troca catiónica (CTC). Com recurso a software apropriado (sistemas de informação geográfica - SIG), foi possível relacionar individualmente as amostras de solo analisadas com o sistema cultural (sequeiro, menos de 15 anos em regadio, entre 15 e 25 anos em regadio e mais de 25 anos em regadio) e com o grupo de solos presente (Regossolos, Cambissolos, Vertissolos, Calcissolos, Luvissolos e Fluvissolos), sendo então possível analisar a influência do sistema cultural no complexo de troca do solo e a forma como os diferentes grupos de solos eram influenciados pelo regadio. Com excepção dos Vertissolos, os resultados obtidos confirmam um decréscimo generalizado dos valores da capacidade de troca catiónica, soma de bases de troca e grau de saturação em bases e um aumento do teor de sódio de troca nos solos explorados em regadio, que tende a agravar-se ao longo do tempo, pelo menos nos primeiros 30 anos desta prática.Being the main goal of this work the analysis of the changes in the soil exchange complex brought by the continued irrigation practice, we collect georeferenciatilly, in the 12400 ha constituting the Caia Irrigation Perimeter and adjacent areas (located in the Elvas and Campo Major region, Portalegre district, Portugal), 14280 topsoil samples (020 cm), which, after mixed 10 by 10, in a way that each aggregate sample represented 11.1 ha, were analyzed for soil exchange complex composition and for soil exchange capacity (CEC). With the use of appropriate software (Geographic Information Systems-GIS), it was possible to relate the results of individual samples analysed with the cultural system (rain feed, less than 15 years in irrigation, between 15 and 25 years in irrigation and more than 25 years in irrigation) and the soil group (Regosols, Cambisols, Vertisols, Calcisols, Luvisols and Fluvisols), and then analyze the influence of the cultural system in the soil exchange complex and how the different soil groups were influenced by irrigation. With the Vertisols exception, the results confirm a decline in soil exchange capacity, sum of bases and base saturation ratio values and an increase in the exchange sodium percentage, which tends to get worse over time, at least in the first 30 years of this practice.

Viral M-dsRNAs encoding yeast killer toxins share similar genomic organization, but no overall sequence identity. The dsRNA full-length sequences of several known M-viruses either have yet to be completed, or they were shorter than estimated by agarose gel electrophoresis. High-throughput sequencing was used to analyze some M-dsRNAs previously sequenced by traditional techniques, and new dsRNAs from atypical killer strains of Saccharomyces cerevisiae and Torulaspora delbrueckii. All dsRNAs expected to be present in a given yeast strain were reliably detected and sequenced, and the previously-known sequences were confirmed. The few discrepancies between viral variants were mostly located around the central poly(A) region. A continuous sequence of the ScV-M2 genome was obtained for the first time. M1 virus was found for the first time in wine yeasts, coexisting with Mbarr-1 virus in T. delbrueckii. Extra 5′- and 3′-sequences were found in all M-genomes. The presence of repeated short sequences in the non-coding 3′-region of most M-genomes indicates that they have a common phylogenetic origin. High identity between amino acid sequences of killer toxins and some unclassified proteins of yeast, bacteria, and wine grapes suggests that killer viruses recruited some sequences from the genome of these organisms, or vice versa, during evolution.

Traditional rice (Oryza sativa L.) management (tillage and flooding) is unsustainable due to soil degradation and the large amount of irrigation water used, an issue which is exacerbated in the Mediterranean region. Therefore, there is a need to explore rice management strategies in order to improve water-use efficiency and ensure its sustainability. Thus, field experiments were conducted to determine the medium-term effects of different irrigation and tillage methods combined with a single compost application on water and rice productivity, as well as food safety in a semiarid Mediterranean region. The management systems evaluated were: sprinkler irrigation in combination with no-tillage (SNT), sprinkler irrigation in combination with conventional tillage (ST), which were implemented in 2015, and flooding irrigation in combination with conventional tillage (FT), and their homologues (SNT-C, ST-C, and FT-C) with single compost application in 2015. In reference to rice grain yield, the highest values were observed under ST treatment with 10 307 and 11 625 kg ha−1 in 2018 and 2019 respectively; whereas between FT and SNT there were no significant differences, with 8 140 kg ha−1 as mean value through the study. Nevertheless, sprinkler irrigation allowed saving 55% of the total amount of water applied in reference to flooding irrigation. Furthermore, the highest arsenic concentration in grains was found under FT but it decreased with compost application (FT-C) and especially with sprinkler irrigation, regardless of tillage management systems. However, sprinkler irrigation favors the cadmium uptake by plants, although this process was reduced under SNT in reference to ST, and especially under amended compost treatments. Therefore, our results suggested that a combination of sprinkler irrigation and compost application, regardless of the tillage system, could be an excellent strategy for rice management for the Mediterranean environment in terms of water and crop productivity as well as food safety. [ABSTRACT FROM AUTHOR]

Traditional rice (Oryza sativa L.) production by flooding is a source of greenhouse gases (GHG), especially methane. The high consumption of water, as well as the chemical and physical degradation caused by these traditional practices in rice soils, is promoting a decrease in rice production in the Mediterranean area. The aim of this study was to monitor GHG emissions and the net ecosystem carbon balance (NECB) from rice produced with sprinkler irrigation techniques and also assess the impact of olive mill waste compost (C-OW) application and tillage on GHG emissions and the NECB. A field experiment for irrigated rice production was implemented by considering four different treatments: (1) tillage (T); (2) no tillage—direct seeding techniques (DS); (3) application of C-OW followed by tillage (TC); and (4) application of C-OW followed by direct seeding (DSC). The C-OW was only applied in the first year at a dose of 80 Mg ha−1. GHG emissions were monitored over three years in these four treatments in order to estimate the direct (first year) and residual (third year) effects of such practices. The application of C-OW caused an increase of 1.85 times the emission of CO2-C in the TC-DSC compared to the T-DS in the first year. It is noteworthy that the TC treatment was the only one that maintained an emission of CO2-C that was 42% higher than T in the third year. Regardless of the treatments and year of the study, negative values for the cumulative CH4 were found, suggesting that under sprinkler irrigation, CH4 oxidation was the dominant process. A decrease in N2O emissions was observed under direct seeding relative to the tillage treatments, although without significant differences. Tillage resulted in an increase in the global warming potential (GWP) of up to 31% with respect to direct seeding management in the third year, as a consequence of the greater carbon oxidation caused by intensive tillage. DS presented a positive NECB in the accumulation of C in the soil; therefore, it provided a greater ecological benefit to the environment. Thus, under Mediterranean conditions, rice production through a sprinkler irrigation system in combination with direct seeding techniques may be a sustainable alternative for rice crops, reducing their GWP and resulting in a lower carbon footprint. However, the use of C-OW as an organic amendment could increase the GHG emissions from rice fields irrigated by sprinklers, especially under tillage conditions. [ABSTRACT FROM AUTHOR]