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Traditional rice (Oryza sativa L.) cropping systems under flooding irrigation combined with conventional tillage management are under increasing threat due to a loss of soil quality and a scarcity of water resources, especially in Mediterranean environments. Hence, the development of such management strategies as no-tillage, the application of organic amendments, and water-saving methods could be vital in enhancing the sustainability of rice crops. This work tests the combination of various management systems for growing rice under Mediterranean conditions. It assesses for the first time their influence on soil properties and rice yield components. A field experiment was carried out in southern Spain over 3 years (2015–2017) with six treatments: tillage and continuous flood irrigation either without or with application of two-phase olive mill waste compost; tillage and sprinkler irrigation either without or with application of mill waste compost; direct seeding (no tillage) and sprinkler irrigation either without or with application of mill waste compost. Applying mill waste compost in combination with sprinkler-rice systems improved significantly the soils’ properties. Sprinkler-rice yield was similar to that of rice under tillage and flooding, but it used less irrigation water. In 2017, the greatest rice yield occurred under tillage and sprinkler irrigation with application of mill waste compost (8581 kg ha-1), showing the importance of soil organic matter on yields. Additionnally, flooding increased significantly weed density because it lowered herbicide efficacy, making weed control a key issue for rice yields. Thus, the novelty of this communication is showing that the application of mill waste compost combined with sprinkler irrigation may be a sustainable alternative for rice crops under Mediterranean conditions, increasing the water efficiency and reducing weed pressure, while improving different soil properties.

BACKGROUND Irrigation and tillage systems alone or in combination with organic amendments can strongly influence soil properties, which in turn may also modify the environmental fate of any pesticides applied. This study was aimed at determining how amendment with composted olive‐mill waste (W) influenced leaching, sorption, and persistence of the herbicide clomazone in rice field soils under different tillage and irrigation management practices. The field trial conducted covered 3 years in succession, with six treatments: irrigation by sprinkler and conventional tillage without (ST) or with W application (80 Mg ha−1) (STW), irrigation by sprinkler but no tillage (SNT), irrigation by sprinkler but no tillage with W application (SNTW), and continuous flooding irrigation and tillage without (FT) and with W application (FTW). RESULTS Application of W significantly increased the adsorption of clomazone to soil in the first and third years. In the first year, the persistence of clomazone under aerobic (t1/2 = 33.1–36.3 days) and anaerobic incubation conditions (t1/2 = 3.43–10.8 days) decreased after W application to t1/2 values in the ranges 18.1–29.7 and 3.06–5.44 days, respectively. However, in the third year, although clomazone persistence increased significantly in SNT and ST when W was applied under both incubation conditions, it decreased significantly in FT management under anaerobic incubation conditions. The addition of W led to less leaching of clomazone, particularly for the FT case where the herbicide leaching losses were 2.8 and 2.6 times lower in the first and third years after W addition, respectively. CONCLUSIONS Using W as an organic amendment could be regarded as an invaluable strategy to reduce water contamination by clomazone in rice production, especially under traditional tillage and flooding management. © 2019 Society of Chemical Industry

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