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This study aimed to analyze rice straw alternative managements to maximize the rice-soybean succession yield and to quantify their impacts on soil properties. The experiment was set up in a completely randomized design with six replicates. Nine rice straw managements were evaluated: straw burning (M1), straw harvesting (M2), straw incorporation with disc harrow and two passes (M3) or three passes (M4) of leveling disc harrow, straw incorporation with knife-roller and soybean no-tillage (M5), straw incorporation with knife-roller and two passes (M6) or three passes (M7) of leveling disc harrow, straw incorporation with two passes of knife-roller and two passes (M8) or three passes (M9) of leveling disc harrow. Straw incorporation by knife-roller provided the lowest soil organic matter (SOM) contents due to slow mineralization of fresh straw incorporated shallow into the soil, although SOM increased in the surface layer related to the initial content. Rice-soybean succession yield was more affected by the physical than by the soil chemical properties. The straw incorporation with one pass of knife-roller and two passes of leveling disc harrow (M6) can replace the straw burning, without affecting the rice-soybean succession yield and soil physical quality, with a reduction in machinery operations, allowing early soil tillage. Made available in DSpace on 2022-08-23T11:20:02Z (GMT). No. of bitstreams: 1 rc-2022.pdf: 351346 bytes, checksum: 084e3820154a362375a0dc1d9c8e46f3 (MD5) Previous issue date: 2022

Irrigation strategies are keys to fostering sustainable and climate-resilient rice production by increasing efficiency, building resilience and reducing Greenhouse Gas (GHG) emissions. These strategies are aligned with the Climate-Smart Agriculture (CSA) principles, which aim to maximize productivity whilst adapting to and mitigating climate change. Achieve such mitigation, adaptation, and productivity goals- to the extent possible- is described as climate smartness. Measuring climate smartness is challenging, with recent progress focusing on the use of agronomic indicators in a limited range of contexts. One way to broaden the ability to measure climate-smartness is to use modeling tools, expanding the scope of climate smartness assessments. Accordingly, and as a proof-of-concept, this study uses modeling tools with CSA indicators (i.e., Greenhouse Intensity and Water Productivity) to quantify the climate-smartness of irrigation management in rice and to assess sensitivity to climate. We focus on a field experiment that assessed four irrigation strategies in tropical conditions, Continuous Flooding (CF), Intermittent Irrigation (II), Intermittent Irrigation until Flowering (IIF), and Continuous soil saturation (CSS). The DNDC model was used to simulate rice yields, GHG emissions and water inputs. We used model outputs to calculate a previously developed Climate-Smartness Index (CSI) based on water productivity and greenhouse gas intensity, which score on a scale between−1 (lack of climate-smartness) to 1 (high climate smartness) the climate-smartness of irrigation strategies. The CSS exhibited the highest simulation-based CSI, and CF showed the lowest. A sensitivity analysis served to explore the impacts of climate on CSI. While higher temperatures reduced CSI, rainfall mostly showed no signal. The climate smartness decreasing in warmer temperatures was associated with increased GHG emissions and, to some extent, a reduction in Water Productivity (WP). Overall, CSI varied with the climate-management interaction, demonstrating that climate variability can influence the performance of CSA practices. We conclude that combining models with climate-smart indicators can broaden the CSA-based evidence and provide reproducible research findings. The methodological approach used in this study can be useful to fill gaps in observational evidence of climate-smartness and project the impact of future climates in regions where calibrated crop models perform well.

O manejo apropriado da água de irrigação está entre as técnicas necessárias para atingir não apenas alto potencial produtivo como também maior eficiência no uso de água e insumos nos sistemas agrícolas irrigados. Objetivou-se com este estudo determinar a influência do manejo da irrigação no desempenho agronômico de cultivares de arroz irrigado e na eficiência de uso da água, em várzeas tropicais. O estudo foi constituído por três experimentos: um, conduzido no Campo Experimental da Unitins, em Formoso do Araguaia, TO em Plintossolo Háplico distrófico; e dois experimentos foram realizados na Fazenda Palmital, da Embrapa Arroz e Feijão, no município de Goianira, GO, em Gleissolo Háplico distrófico. Foram avaliados quatro manejos de água: Inundação contínua - IC (método convencional, com lâmina de água contínua durante todo ciclo); Irrigação intermitente em todo ciclo - II; Irrigação intermitente até a floração, após contínua - IIF e Solo saturado - SS (solo mantido acima da capacidade de campo, mas sem lâmina de água), e quatro cultivares BRS Pampeira, BRS Catiana, BRS A702 CL e IRGA 424. O delineamento experimental usado foi o inteiramente casualizado, com cinco repetições, no esquema de parcelas divididas, constituídas pelos quatro manejos de água, e as subparcelas pelas cultivares. Os resultados mostraram que o manejo da irrigação solo saturado propicia produtividade média de grãos das cultivares de arroz irrigado similar ou superior em até 16% ao manejo tradicional de água com inundação contínua e com redução de até 82% do volume de água aplicado, o que resulta em maior eficiência de uso da água. O manejo solo saturado e irrigação intermitente constituem estratégias para racionalizar o uso dos recursos hídricos na orizicultura. Made available in DSpace on 2021-06-15T02:21:34Z (GMT). No. of bitstreams: 1 raes-2021-2.pdf: 256322 bytes, checksum: 3d9340cfe2e81d7c456c2b38848f3113 (MD5) Previous issue date: 2021 Edição especial.

In order to study the effect of use organic agriculture avoids the use of synthetic fertilizers and emphasizes the use of organic inputs to provide nutrients to the plants. This study had as aim to evaluate the effect of organic management time on nutrition and productivity of sugarcane. The nutrition levels and the productivity of sugarcane plantations were evaluated in areas cultivated for two, six and ten years in the organic production system compared with a sugarcane plantation cultivated for ten years in the conventional system. The sugarcane organic production system enhanced the nutrition levels of the plants and raised the crops productivity. After ten years of organic cultivation, there was an increase of 43, 42.8 and 32% in the leaf contents of potassium (K), phosphorus (P) and nitrogen (N), respectively, in relation to the conventional production system and an increase of 209% in the sugarcane productivity. The management of the fertilizers inputs used in the sugarcane organic production system is adequate for the plants nutrition, with positive result on the crops productivity. The effects are more visible after six and ten years of management in the organic production system. In the organic production system, after ten and six years, it could be suggested that the productivity was 209 and 98% higher in comparison to the productivity of the cane cultivated under the conventional system, areas Org.10 and Org.6, respectively.