ABSTRACT The Soil Management Assessment Framework (SMAF) was developed in the U.S.A. and has been used as a tool for assessing and quantifying changes in soil quality/health (SQ) induced by land uses and agricultural practices in that region and elsewhere throughout the world. An initial study using SMAF in Brazil was recently published, but additional research for a variety of soils and management systems is still needed. Our objective was to use data from five studies in southern Brazil to evaluate the potential of SMAF for assessing diverse land-use and management practices on SQ. The studies examined were: (i) horizontal and vertical distribution of soil properties in a long-term orange orchard; (ii) impacts of long-term land-use change from native vegetation to agricultural crops on soil properties; (iii) effects of short-term tillage on soil properties in a cassava production area; (iv) changes in soil properties due to mineral fertilizer and pig slurry application coupled with soil tillage practices; and (v) row and inter-row sowing effects on soil properties in a long-term no-tillage area. The soils were classified as Oxisols, with clay content ranging from 180 to 800 g kg-1. Six SQ indicators [pH(H2O), P, K, bulk density, organic C, and microbial biomass] were individually scored using SMAF curves and integrated into an overall Soil Quality Index (SQI) focusing on chemical, physical, and biological sectors. The SMAF was sensitive for detecting SQ changes induced by different land uses and management practices within this wide textural range of Brazilian Oxisols. The SMAF scoring curve algorithms properly transformed the indicator values expressed in different units into unitless scores ranging from 0-1, thus enabling the individual indicators to be combined into an overall index for evaluating land-use and management effects on soil functions. Soil sector scores (i.e., chemical, physical, and biological) identify the principal soil limitations and can therefore be used to establish priorities for specific management actions. The SMAF can be used as a tool for assessing SQ in Brazilian soils, thus helping farmers, land managers, and politicians make better decisions regarding sustainable land-use and management practices.

La agricultura puede abordar simultáneamente los desafíos de producción global de alimentos, forrajes, fibra y energía, siempre que los recursos suelo, agua y aire no se comprometan al hacerlo. Nuestro objetivo es presentar un concepto de gestión del paisaje como un enfoque para integrar múltiples fuentes de materia prima para bioenergía a los sistemas actuales de producción de cultivos. Esto se hace para mostrar cómo múltiples demandas globales pueden ser atendidas y resueltas de manera sostenible. Discutimos cómo la investigación colaborativa entre el servicio de investigación agrícola del USDA (ARS), el Laboratorio Nacional de Idaho del Departamento de Energía (DOE) de Estados Unidos (INL) (DOE), y varios socios de investigación y extensión de la Universidad, junto con representantes de la industria [conocidos como el equipo de proyecto de evaluación de energía renovable (REAP)] condujo al desarrollo de lineamientos informáticos para guiar la toma de decisiones en la producción sostenible de materia prima para generación de bioenergía. El producto conocido inicialmente como «herramienta de rastrojo de maíz» y más recientemente como «Landscape Environmental Assessment Framework (LEAF) está diseñado para reconocer la importancia de la diversidad de la naturaleza y por lo tanto, puede utilizarse para guiar la producción sostenible de materia prima, sin impactos negativos en los servicios de los ecosistemas críticos. Usando un predio agrícola de 57 hectáreas en Iowa central, USA, mostramos cómo las decisiones del productor sobre la cosecha de rastrojo de maíz (Zea mays L.), en el cinturón maicero de Estados Unidos, pueden hacerse en forma más sostenible. Este ejemplo también respalda las conclusiones del equipo REAP en cuanto a que no debe ser cosechado el rastrojo si los rendimientos medios de grano son menores de 11 Mg ha-1 a menos que se implementen prácticas más equilibradas de manejo del paisaje. La herramienta también ilustra la importancia de la gestión del subsuelo y de estrategias de cosecha del rastrojo específicas para cada lugar.

Agriculture can simultaneously address global food, feed, fiber, and energy challenges provided our soil, water, and air resources are not compromised in doing so. Our objective is to present a landscape management concept as an approach for integrating multiple bioenergy feedstock sources into current crop production systems. This is done to show how multiple, increasing global challenges can be met in a sustainable manner. We discuss how collaborative research among USDA-Agricultural Research Service (ARS), US Department of Energy (DOE) Idaho National Laboratory (INL), several university extension and research partners, and industry representatives [known as the Renewable Energy Assessment Project (REAP) team] has led to the development of computer-based decision aids for guiding sustainable bioenergy feedstock production. The decision aids, known initially as the «Corn Stover Tool» and more recently as the «Landscape Environmental Assessment Framework» (LEAF) are tools designed to recognize the importance of nature’s diversity and can therefore be used to guide sustainable feedstock production without having negative impacts on critical ecosystem services. Using a 57 ha farm site in central Iowa, USA, we show how producer decisions regarding corn (Zea mays L.) stover harvest within the US Corn Belt can be made in a more sustainable manner. This example also supports REAP team conclusions that stover should not be harvested if average grain yields are less than 11 Mg ha-1 unless more balanced landscape management practices are implemented. The tools also illustrate the importance of sub-field management and site-specific stover harvest strategies

El desarrollo de estrategias para utilizar biomasa celulósica para la producción de bioenergía permitiría utilizar recursos que no son fuente de alimento para el ser humano. Este estudio comparó estrategias de cosecha de rastrojo de maíz (Zea mays L.) en 50 ha ubicadas sobre la Asociación de suelos Clarion-Nicollet-Webster cerca de Emmetsburg, Iowa, Estados Unidos. Se analizaron muestras de suelo superficial (0 a 15 cm) después de cada cosecha para monitorear los cambios en el carbono orgánico del suelo (COS), pH, fósforo (P) y potasio ( K ). Los rendimientos de grano en 2008, antes de que se impusieran los tratamientos de cosecha de rastrojo, promediaron 11,4 Mg ha-1. En 2009, 2010 y 2011 los rendimientos de grano promediaron 10,1, 9,7 y 9,5 Mg ha-1, respectivamente. Aunque los rendimientos de grano después de impuestos los tratamientos fueron inferiores a los del 2008, no se encontraron diferencias significativas entre los tratamientos. Las tasas promedio de cuatro años de cosecha de rastrojo variaron entre 1,0 y 5,2 Mg ha- 1, lo que representó del 12 al 60% de la biomasa por encima del suelo. El COS mostró una leve disminución durante el estudio, pero el cambio no estuvo relacionado con los tratamientos de cosecha de rastrojo, sino con la intensidad de labranza y los menores rendimientos del cultivo. En general los resultados son consistentes con otros estudios obtenidos en el medio oeste de Estados Unidos, indicando que el rastrojo del maíz no debe cosecharse si los rendimientos medios de grano son menores a 11 Mg ha-1.

Developing strategies to collect and use cellulosic biomass for bioenergy production is important because those materials are not used as human food sources. This study compared corn (Zea mays L.) stover harvest strategies on a 50 ha Clarion-Nicollet-Webster soil Association site near Emmetsburg, Iowa, USA. Surface soil samples (0 to 15 cm) were analyzed after each harvest to monitor soil organic carbon (SOC), pH, phosphorus (P) and potassium (K) changes. Grain yields in 2008, before the stover harvest treatments were imposed, averaged 11.4 Mg ha-1. In 2009, 2010, and 2011 grain yields averaged 10.1, 9.7, and 9.5 Mg ha-1, respectively. Although grain yields after stover harvest strategies imposed were lower than in 2008, there were no significant differences among the treatments. Four-year average stover collection rates ranged 1.0 to 5.2 Mg ha-1 which was 12 to 60% of the above-ground biomass. SOC showed a slight decrease during the study, but the change was not related to any specific stover harvest treatment. Instead, we attribute the SOC decline to the tillage intensity and lower than expected crop yields. Overall, these results are consistent with other Midwestern USA studies that indicate corn stover should not be harvested if average grain yields are less than 11 Mg ha-1