• Energy Research

Faidherbia albida is an important tree species in the parkland agroforestry system of the Rift Valley region, central and south-eastern Ethiopia. Positive effects of F. albida on crop production are widely recognised. However, the effects of tree pruning, zone and fertiliser interactions on crop growth have not been addressed in earlier studies. A field experiment containing three levels of tree pruning (100% pruned, 50% pruned, and unpruned) as main plots, and application of recommended rates of N and P fertilisers as sub-plots, was conducted during the 2015 and 2016 growing seasons. Maize grain yield and biomass, light intensity, and soil nutrients and moisture were measured at different positions from each F. albida tree trunk (0–2, 2–4 and 4–6 m) and in crop-only plots. Biomass and yield of maize were significantly greater under tree canopies compared to crop-only plots in both the 2015 and 2016 growing seasons, regardless of pruning levels. Fertilisation significantly increased yields under tree canopies compared to crop-only plots in both years. Light intensity increased with distance from trees and with greater pruning levels. Soil carbon and nutrient concentrations and moisture content decreased with increasing distance from tree and with soil depth. These results suggest that maize production and profitability could be maintained or improved through only partial pruning of F. albida rather than pollarding, and by preferentially applying fertilisers in normal and wet years. Recommendations need to be evaluated in a total system context including other rotational crops, fuel, livestock and socio-economic factors.

Ongoing climate change is already affecting crop production patterns worldwide. Our aim was to investigate how increasing temperature and CO2 as well as changes in precipitation could affect potential yields for different historical pedoclimatic conditions at high latitudes (i.e., >55°). The APSIM crop model was used to simulate the productivity of four annual crops (barley, forage maize, oats, and spring wheat) over five sites in Sweden ranging between 55 and 64°N. A first set of simulations was run using site-specific daily weather data acquired between 1980 and 2005. A second set of simulations was then run using incremental changes in precipitation, temperature and CO2 levels, corresponding to a range of potential future climate scenarios. All simulation sets were compared in terms of production and risk of failure. Projected future trends showed that barley and oats will reach a maximum increase in yield with a 1°C increase in temperature compared to the 1980–2005 baseline. The optimum temperature for spring wheat was similar, except at the northernmost site (63.8°N), where the highest yield was obtained with a 4°C increase in temperature. Forage maize showed best performances for temperature increases of 2–3°C in all locations, except for the northernmost site, where the highest simulated yield was reached with a 5°C increase. Changes in temperatures and CO2 were the main factors explaining the changes in productivity, with ~89% of variance explained, whereas changes in precipitation explained ~11%. At the northernmost site, forage maize, oats and spring wheat showed decreasing risk of crop failure with increasing temperatures. The results of this modeling exercise suggest that the cultivation of annual crops in Sweden should, to some degree, benefit from the expected increase of temperature in the coming decades, provided that little to no water stress affects their growth and development. These results might be relevant to agriculture studies in regions of similar latitudes, especially the Nordic countries, and support the general assumption that climate change should have a positive impact on crop production at high latitudes.

Les analyses de la sécurité alimentaire avec les modèles de systèmes agricoles se concentrent souvent sur les indicateurs de disponibilité alimentaire, avec un traitement limité des trois autres dimensions : accès à la nourriture, stabilité et utilisation. Nous illustrons comment trois indicateurs d'accès (dépenses de consommation alimentaire, échelle d'insécurité alimentaire et diversité alimentaire) et leur stabilité peuvent être intégrés dans un modèle dynamique au niveau des ménages d'un système de production à base de maïs dans les hautes terres du Kenya et un modèle régional dynamique de production et de commercialisation des ovins au Mexique. Bien que stylisées en raison des limites des preuves empiriques, les analyses suggèrent que l'inclusion de plusieurs indicateurs d'accès peut fournir des informations parce que les indicateurs réagissent différemment aux chocs de production, à la croissance de la demande et aux programmes fournissant des subventions à la production. Nous illustrons également comment examiner la stabilité des résultats de la sécurité alimentaire en réponse aux chocs en utilisant des paramètres de dureté (capacité à résister aux chocs) et d'élasticité (capacité à revenir aux conditions précédentes). Les données requises pour une mise en œuvre empirique plus large de ces méthodes comprennent la mesure - de préférence à intervalles fréquents au fil du temps - des indicateurs d'accès à la nourriture, mais aussi de leurs déterminants et de leurs liens avec les résultats dans les modèles de systèmes agricoles. Les analyses de l'accès et de la stabilité des aliments seront très utiles pour évaluer les impacts du changement climatique sur la sécurité alimentaire, lorsque les systèmes alimentaires subissent des changements transformateurs, ainsi que pour identifier les interventions prioritaires et les publics cibles. Los análisis de la seguridad alimentaria con modelos de sistemas agrícolas a menudo se centran en indicadores de disponibilidad de alimentos, con un tratamiento limitado de las otras tres dimensiones: acceso, estabilidad y utilización de los alimentos. Ilustramos cómo tres indicadores de acceso (gastos de consumo de alimentos, una escala de inseguridad alimentaria y diversidad dietética) y su estabilidad pueden incorporarse en un modelo dinámico a nivel de hogar de un sistema de producción basado en el maíz en las tierras altas de Kenia y un modelo regional dinámico de producción y comercialización de ovejas en México. Aunque estilizados debido a los límites de la evidencia empírica, los análisis sugieren que la inclusión de indicadores de acceso múltiple puede proporcionar información porque los indicadores responden de manera diferente a los choques de producción, el crecimiento de la demanda y los programas que proporcionan subsidios a la producción. También ilustramos cómo examinar la estabilidad de los resultados de seguridad alimentaria en respuesta a los choques utilizando métricas de dureza (capacidad para resistir choques) y elasticidad (capacidad para volver a las condiciones anteriores). Los datos necesarios para una implementación empírica más generalizada de estos métodos incluyen la medición, preferiblemente a intervalos frecuentes en el tiempo, de los indicadores de acceso a los alimentos, pero también sus determinantes y vínculos con los resultados en los modelos de sistemas agrícolas. Los análisis del acceso a los alimentos y la estabilidad serán más valiosos para evaluar los impactos del cambio climático en la seguridad alimentaria, cuando los sistemas alimentarios están experimentando un cambio transformador y para identificar intervenciones prioritarias y audiencias objetivo. Analyses of food security with agricultural systems models often focus on indicators of food availability, with limited treatment of the other three dimensions: food access, stability and utilization. We illustrate how three indicators of access (food consumption expenditures, a food insecurity scale and dietary diversity) and their stability can be incorporated into a dynamic household-level model of a maize-based production system in the Kenya highlands and a dynamic regional model of sheep production and marketing in Mexico. Although stylized due to limits on empirical evidence, the analyses suggest that inclusion of multiple access indicators can provide insights because the indicators respond differently to production shocks, demand growth and programs providing production subsidies. We also illustrate how to examine stability of food security outcomes in response to shocks using metrics of hardness (ability to withstand shocks) and elasticity (ability to return to previous conditions). The data required for more widespread empirical implementation of these methods include measurement—preferably at frequent intervals over time—of food access indicators, but also their determinants and linkages to outcomes in agricultural systems models. Analyses of food access and stability will be most valuable for assessments of food security impacts of climate change, when food systems are undergoing transformative change and to identify priority interventions and target audiences. غالبًا ما تركز تحليلات الأمن الغذائي مع نماذج النظم الزراعية على مؤشرات توافر الغذاء، مع معالجة محدودة للأبعاد الثلاثة الأخرى: الوصول إلى الغذاء والاستقرار والاستخدام. نوضح كيف يمكن دمج ثلاثة مؤشرات للوصول (نفقات استهلاك الغذاء، ومقياس انعدام الأمن الغذائي والتنوع الغذائي) واستقرارها في نموذج ديناميكي على مستوى الأسرة لنظام إنتاج قائم على الذرة في مرتفعات كينيا ونموذج إقليمي ديناميكي لإنتاج الأغنام وتسويقها في المكسيك. على الرغم من أن التحليلات منمقة بسبب القيود المفروضة على الأدلة التجريبية، إلا أنها تشير إلى أن إدراج مؤشرات الوصول المتعدد يمكن أن يوفر رؤى لأن المؤشرات تستجيب بشكل مختلف لصدمات الإنتاج ونمو الطلب والبرامج التي توفر إعانات الإنتاج. كما نوضح كيفية فحص استقرار نتائج الأمن الغذائي استجابة للصدمات باستخدام مقاييس الصلابة (القدرة على تحمل الصدمات) والمرونة (القدرة على العودة إلى الظروف السابقة). تشمل البيانات المطلوبة للتنفيذ التجريبي على نطاق أوسع لهذه الأساليب القياس - ويفضل على فترات متكررة على مر الزمن - لمؤشرات الوصول إلى الغذاء، ولكن أيضًا محدداتها وروابطها بالنتائج في نماذج النظم الزراعية. ستكون تحليلات الوصول إلى الغذاء واستقراره أكثر قيمة لتقييم آثار تغير المناخ على الأمن الغذائي، عندما تمر النظم الغذائية بتغيير تحويلي ولتحديد التدخلات ذات الأولوية والجماهير المستهدفة.

We systematically reviewed the literature on farm household models, with emphasis on those focused on smallholder systems. The models were evaluated on their predictive ability to describe short term (3–10 years) food security of smallholder farm households under climate variability and under different scenarios of climate change. The review of 126, mainly production-oriented, farm household models, showed that integrated analyses of food security at the farm household level are scarce. Some models deal with elements of food security, but the models covered in this review are weak on decision-making theory and risk analyses. These aspects need urgent attention for dealing with more complex adaptation and mitigation questions, in the face of climatic change. Approaches that make use of decision making theory and combine the strengths of (dynamic) mathematical programming and expert systems decision models seem promising in this respect. They could support the robust evaluation of climate change impacts and adaptive management options on smallholder systems.

AbstractWhile there is increasing evidence of the sustainability benefits of diversified systems in the organic cropping sector, this has been much less investigated with organic livestock farming. To fill this knowledge gap, we surveyed a sample of 128 European organic multi-species livestock farms located across seven countries – Austria, Belgium, France, Germany, Italy, Sweden and Switzerland – and covering a large range of livestock species combinations. We recorded 1574 variables as raw data out of which we calculated 107 indicators describing farm structure, management and several sustainability dimensions: resource use efficiency and conservation, animal, land and work productivities, animal and human welfare. After technical validation of the data, we withdrew 26 farms and the database covers 102 farms. This database is well suited to unveil relationships between various dimensions of organic multi-species livestock farm sustainability and their structure and management. It can help reveal sustainable strategies for organic multi-species livestock farming systems and understand levers or barriers to their development.

APSIM Next Generation was used to simulate the phenological development and biomass production of silage maize for high latitudes (i.e., >55°). Weather and soil data were carefully specified, as they are important drivers of the development and growth of the crop. Phenology related parameters were calibrated using a factorial experiment of simulations and the minimization of the root mean square error of observed and predicted phenological scaling. Results showed that the model performed well in simulating the phenology of the maize, but largely underestimated the production of biomass. Several factors could explain the discrepancy between observations and predictions of above-ground dry matter yield, such as the current formalization of APSIM for simulating the amount of radiation absorbed by the crop at high latitudes, as the amount of diffuse light and intercepted light increases with latitude. Another factor that can affect the accuracy of the predicted biomass is the increased duration of the day length observed at high latitudes. Indeed, APSIM does not yet formalize the effects of extreme day length on the balance between photorespiration and photosynthesis on the final balance of biomass production. More field measurements are required to better understand the drivers of the underestimation of biomass production, with a particular focus on the light interception efficiency and the radiation use efficiency.