From detailed to summary models of the crop-soil system for larger scale applications

Crop growth models developed at field level are increasingly used in larger scale studies often in combination with other models to explore management options at the whole-farm scale or for integrated assessment at regional level (e.g. Giller et al., 2006; van Ittersum et al., 2008). Unclear is whether the mechanistic detail of dynamic simulation crop models is required for such applications or whether summary models may be sufficient. To address this issue and to identify relationships that need specific attention in future research, we compared simulations of crop production by two models with a different degree of mechanistic detail. (Résumé d'auteur

Improved feeding and forages at a crossroads: Farming systems approaches for sustainable livestock development in East Africa

Dairy development provides substantial potential economic opportunities for smallholder farmers in East Africa, but productivity is constrained by the scarcity of quantity and quality feed. Ruminant livestock production is also associated with negative environmental impacts, including greenhouse gas (GHG) emissions, air pollution, high water consumption, land-use change, and loss of biodiversity. Improved livestock feeding and forages have been highlighted as key entry point to sustainable intensification, increasing food security, and decreasing environmental trade-offs including GHG emission intensities. In this perspective article, we argue that farming systems approaches are essential to understand the multiple roles and impacts of forages in smallholder livelihoods. First, we outline the unique position of forages in crop-livestock systems and systemic obstacles to adoption that call for multidisciplinary thinking. Second, we discuss the importance of matching forage technologies with agroecological and socioeconomic contexts and niches, and systems agronomy that is required. Third, we demonstrate the usefulness of farming systems modeling to estimate multidimensional impacts of forages and for reducing agro-environmental trade-offs. We conclude that improved forages in East Africa are at a crossroads: if adopted by farmers at scale, they can be a cornerstone of pathways toward sustainable livestock systems in East Africa.</p

Efecto de sustratos con compost y fertilización nitrogenada sobre la fotosíntesis, precocidad y rendimiento de pimiento (Capsicum annuum)

Fast-growing seedlings have larger immediate nutrient demands as compared with adult plants. A tray experiment was conducted to evaluate the fertilization of sweet pepper transplants growing on different substrates [Control (60% Sphagnum peat + 40% perlite), Mix I (45% Sphagnum peat + 30% perlite + 25% farmyard compost), Mix II (30% Sphagnum peat + 20% perlite + 50% farmyard compost), and Commercial (40% compost + Sphagnum peat + perlite + vermiculite)] with weekly applications of nitrogen N at rates of 150 and 300 mg&middot;L-1, compared to a control without fertilization. Seedlings were transplanted in a randomized, complete block design with four replications. Leaf area and fresh and dry weights of leaves, stems and roots were measured for the transplants; the leaf weight ratio, specific leaf area, absolute and relative growth rates, leaf expansion rates, leaf area duration, and net assimilation rate were calculated. Precocity, early yield, and total yield were measured for the fi eld crop. The application of nitrogen had positive effects on most growth parameters of seedlings growing on substrates with compost, promoting increased precocity and yield in the transplanted crop. Few benefits from nitrogen fertilization were observed for seedlings growing on substrates without compost. The main effect of the latter is to improve the efficiency of capture of the applied nitrogen, due to better water retention and ion-exchange capacity.Los plantines presentan elevada demanda de nutrientes como resultado de su alta tasa de crecimiento en relaci&oacute;n a las plantas adultas. Para evaluar la adici&oacute;n de nitr&oacute;geno a sustratos preparados con y sin materiales compostados en la producci&oacute;n de pimiento, se realiz&oacute; un ensayo fertilizando plantines cultivados en diferentes sustratos: Testigo (60% turba de Sphagnum + 40% perlita), Mezcla I (45% turba de Sphagnum + 30% perlita + 25% material vegetal compostado), Mezcla II (30% turba de Sphagnum+ 20% perlita + 50% material vegetal compostado) y un sustrato Comercial (turba de Sphagnum + 40% compost + perlita + vermiculita) con 150 y 300 mg&middot;L-1 de nitr&oacute;geno por semana, manteniendo un testigo sin fertilizar. Los plantines fueron transplantados en invernadero seg&uacute;n un dise&ntilde;o de bloques completos aleatorizados con cuatro repeticiones. Previo al transplante se determin&oacute; &aacute;rea foliar, pesos fresco y seco de hoja, tallo y ra&iacute;z, se calcul&oacute; la proporci&oacute;n areal de hojas, &aacute;rea foliar espec&iacute;fi ca, tasas de crecimiento absolutas y relativas en fresco y en seco, tasa de expansi&oacute;n foliar absoluta y relativa, duraci&oacute;n del &aacute;rea foliar y tasa de asimilaci&oacute;n neta de los plantines. En el cultivo se determin&oacute; precocidad, rendimiento precoz y total. La fertilizaci&oacute;n nitrogenada de la mezcla de sustrato testigo fue insuficiente para que los plant&iacute;nes alcanzaran los valores obtenidos al cultivarlos en las mezclas de sustratos con compost. Por lo tanto, es posible que el principal efecto ben&eacute;fico de los materiales compostados sea disminuir la lixiviaci&oacute;n de nutrientes desde la matriz del sustrato gracias a la mayor retenci&oacute;n h&iacute;drica y al aumento de la capacidad de intercambio de iones. &nbsp

Implications of landscape configuration on understory forage productivity: a remote sensing assessment of native forests openings

Sound management of native forests used for cattle grazing requires understanding the dynamics of forage productivity in the openings. Despite their importance, forage productivity drivers in highly heterogeneous forested landscapes, or their variability over the year, are still unclear. The aim of this work is to find predictors of Normalized Difference Vegetation Index (NDVI) variation in the openings of native temperate forests and to evaluate how these predictors change within the growing season. We used high spatial resolution remote sensing imagery from NW Patagonia to separate forest openings from tree dense canopy. We obtained data of each opening related with herbaceous and shrub forage productivity and calculated landscape metrics. We estimated a multiple linear regression model for predicting NDVI in each season. Beyond known variables related with forage productivity (altitude, precipitation, etc.), the shape of forest’ openings appeared as relevant in predicting NDVI. Higher values of forest opening perimeters were related with a decrease in NDVI in spring when soil water content is not limiting and conversely with an increase in NDVI in summer when water is limiting growth. These results suggest that environmental drivers such as temperature and soil moisture inside the opening, and competition or facilitation process between trees and grasses are mediated by the shape of the opening. Management of heterogeneous native forests for cattle raising requires considering the shape of the openings to maximize forage productivity.Fil: Trinco, Fabio Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural. - Universidad Nacional de Rio Negro. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural; ArgentinaFil: Rusch, Verónica E.. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Howison, Ruth A.. University of Groningen; Países BajosFil: Garibaldi, Lucas Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural. - Universidad Nacional de Rio Negro. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural; ArgentinaFil: Tittonell, Pablo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; Argentin

Soil food-web energy fluxes reveal diverse responses to smallholder land-use choices in temperate forests

The consequences of land-use change for soil fauna communities and soil functionality are hard to quantify and poorly understood. Energy fluxes provide a quantitative framework to link soil food webs to ecosystem functions. Here, we examined topsoil fauna in a forest-agriculture matrix in North Patagonia, Argentina, to assess the variation of soil food-web functioning across a gradient of land-use intensity. The sampled plots included reference forests, cattle grazing in forests, sheep grazing in meadows, perennial berry crops and seasonal vegetable crops. In each plot, we extracted soil fauna, measured their body sizes, estimated metabolic rates, and applied the soil food-web energy fluxes approach to assess associated trophic functions. Our findings revealed a greater total faunal biomass and energy flux in most land-use systems compared to native forests, while the number of interactions and the energetic inequality (unevenness in resource consumption) did not show a single pattern. Soil organic matter (SOM) consumption increased in sheep-grazed meadows and seasonal plots, while litter transformation decreased in the latter, and microbivory increased in most land-uses. The ratio between SOM consumption and faeces production, was greater in sheep-grazed meadows and seasonal plots, indicating a lower contribution to C sequestration by soil fauna. Herbivory and predation showed different patterns between seasons, but a reduced top-down herbivore control potential was found under sheep grazing. Overall, native and cattle-grazed forests showed lower energy fluxes but more balanced ecosystem functions. Perennial crops hosted more interactions and a similar potential for carbon storage and herbivore control as forests. In sheep-grazed meadows and seasonal crops, increased soil fauna biomass and energy flux were mainly reflected in higher SOM consumption. Our research shows how smallholder land-use choices result in different, often contrasting, effects on soil food-web structure and related functions, emphasizing the importance of human decisions for soil functional sustainability.</p

Agroecology in large scale farming:A research agenda

Agroecology promises a third way between common global agriculture tradeoffs such as food production and nature conservation, environmental sustainability and ecosystem services. However, most successful examples of mainstreaming agroecology come from smallholder, family agriculture, that represents only about 30% of the world agricultural area. Mainstreaming agroecology among large scale farmers is urgently needed, but it requires addressing specific questions in research, technology and policy development to support sustainable transitions. Here we take stock of the existing knowledge on some key aspects necessary to support agroecological transitions in large scale farming, considering two contrasting starting points: highly subsidized and heavily taxed agricultural contexts, represented here by the examples of Western Europe and temperate South America. We summarize existing knowledge and gaps around service crops, arthropod-mediated functions, landscape and watershed regulation, graze-based livestock, nature-inclusive landscapes, and policy mechanisms to support transitions. We propose a research agenda for agroecology in large scale farming organized in five domains: (i) Breeding for diversity, (ii) Scalable complexity, (iii) Managing cycles beyond fields and farms, (iv) Sharing the cultivated landscape, and (v) Co-innovation with farmers, value chains and policy makers. Agroecology may result in a renewed impetus in large scale farming, to attract the youth, foster clean technological innovation, and to promote a new generation of large-scale farmers that take pride in contributing to feeding the world while serving the planet and its people