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The war in Ukraine threatened to block 9% of global wheat exports, driving wheat prices to unprecedented heights. We advocate, that in the short term, compensating for such an export shortage will require a coordinated release of wheat stocks, while if the export block persists, other export countries will need to fill the gap by increasing wheat yields or by expanding wheat cropping areas by 8% in aggregate. We estimate that a production increase would require an extra half a million tons of nitrogen fertilizer, yet fertilizer prices are at record levels, driven by rising energy prices. Year-to-year variability plus more frequent climate change-induced crop failures could additionally reduce exports by another 5 to 7 million tons in any given year, further stressing global markets. Without stabilizing wheat supplies through judicious management of stocks and continuing yield improvements, food and national security are at risk across many nations in the world. • The war in Ukraine threatened to block 9% of global wheat exports. • Top export countries will need to increase wheat yields or cropping areas by 8% in aggregate. • A production increase would require an extra half a million tons of nitrogen fertilizer. • Climate induced crop failures could additionally reduce exports by 5–7 million tons. [ABSTRACT FROM AUTHOR]

Abstract: Yields of crops must increase substantially over the coming decades to keep pace with global food demand driven by population and income growth. Ultimately global food production capacity will be limited by the amount of land and water resources available and suitable for crop production, and by biophysical limits on crop growth. Quantifying food production capacity on every hectare of current farmland in a consistent and transparent manner is needed to inform decisions on policy, research, development and investment that aim to affect future crop yield and land use, and to inform on-ground action by local farmers through their knowledge networks. Crop production capacity can be evaluated by estimating potential yield and water-limited yield levels as benchmarks for crop production under, respectively, irrigated and rainfed conditions. The differences between these theoretical yield levels and actual farmers’ yields define the yield gaps, and precise spatially explicit knowledge about these yield gaps is essential to guide sustainable intensification of agriculture. This paper reviews methods to estimate yield gaps, with a focus on the local-to-global relevance of outcomes. Empirical methods estimate yield potential from 90 to 95th percentiles of farmers’ yields, maximum yields from experiment stations, growers’ yield contests or boundary functions; these are compared with crop simulation of potential or water-limited yields. Comparisons utilize detailed data sets from western Kenya, Nebraska (USA) and Victoria (Australia). We then review global studies, often performed by non-agricultural scientists, aimed at yield and sometimes yield gap assessment and compare several studies in terms of outcomes for regions in Nebraska, Kenya and The Netherlands. Based on our review we recommend key components for a yield gap assessment that can be applied at local to global scales. Given lack of data for some regions, the protocol recommends use of a tiered approach with preferred use of crop growth simulation models applied to relatively homogenous climate zones for which measured weather data are available. Within such zones simulations are performed for the dominant soils and cropping systems considering current spatial distribution of crops. Need for accurate agronomic and current yield data together with calibrated and validated crop models and upscaling methods is emphasized. The bottom-up application of this global protocol allows verification of estimated yield gaps with on-farm data and experiments. [Copyright &y& Elsevier]

Dietary changes are closely intertwined with land use changes, and understanding the relative importance of different food items and their driving forces is crucial. Here, we analyzed the changes in China's global cropland footprint for food and feed consumption from 1987 to 2013 and explored the driving forces behind these changes for each food item. China's per capita protein consumption increased by 57%. The global cropland footprint of China's food and feed consumption expanded by 40% during this period. Decomposition analysis demonstrated that population growth was the primary driver of the increased total cropland footprint until 1993, with the subsequent rise in per capita protein consumption becoming the driving force. Thereafter, the increased efficiency of cropland use offset 49% of the total cropland expansion primarily due to improved management technologies. Among the food items analyzed, pork, eggs, and vegetables were identified as the main contributors to the increased total cropland footprint, primarily driven by changes in dietary patterns and their increased inclusion in the human diet. In conclusion, changing human diet towards less monogastric livestock products and improving productivity of concentrate feed crops are essential for mitigating domestic land pressure and ecological degradation in exporting countries. [ABSTRACT FROM AUTHOR]

Highlights • We quantify yield gaps for major grain legume crops in East Africa. • Average yield gap represents 75% of water-limited yield potential. • There is ample room for increasing legume production on existing cropland. • Closure of exploitable yield gap meets future legume demand in Kenya and Tanzania. • Exploitable yield gap closure is not sufficient to meet future legume demand in Ethiopia. Abstract Agricultural production in East Africa (E-Afr) has to increase drastically to meet future food demand. Yield gap assessment provides important information on the degree to which production can be increased on existing cropland. Most research on yield gap analysis has focussed on cereal crops, while legumes have received less attention despite of their relatively large area, and their importance as source of protein in smallholder farming systems in E-Afr. The objectives of this study were to (i) estimate water-limited yield potential (Y w) and yield gaps (Y g) for major grain legume crops in E-Afr, and (ii) estimate how narrowing the current legume Y g can contribute to food self-sufficiency by the year 2050. We focussed on Ethiopia, Kenya, and Tanzania, and five legumes crops including chickpea, common bean, cowpea, groundnut, and pigeonpea. A bottom-up approach which entails that local weather, soil and agronomic data was used as input for crop modelling (SSM-legumes) in a spatial framework, to estimate Y w , actual on-farm yield (Y a), and Y g from local to regional scale. Future legume self-sufficiency was assessed for 2050 demand assuming different Y g closure scenarios. On average, Y a was 25% of Y w across all legume-county combinations, being 15% for Kenya, 23% for Tanzania and 41% for Ethiopia. On average, common bean had the largest Y g of 2.6 Mg ha−1and chickpea the smallest (1.4 Mg ha−1). Closure of the exploitable Y g (i.e., 80% of Y w) can help to meet future legume demand in both Kenya and Tanzania, while it seems not to be sufficient in Ethiopia. [ABSTRACT FROM AUTHOR]

Despite recent improvements in living standards, a substantial proportion of farm households in sub-Saharan Africa (SSA) is food insecure, and increasing crop productivity could help address this problem. We estimated the effect of increasing maize yields with mineral fertilizer on household food security and on regional and national maize supply in two East African countries - Uganda and Tanzania. We estimated maize yield response to nitrogen (N) fertilization with a machine learning model trained on 15,952 observations of maize responses to fertilizer across SSA. Together with spatial price data, we used this model to quantify the profit-maximizing N fertilizer input for a nationally-representative sample of 4188 agricultural households in the two countries. We computed a food availability indicator for all households. The mean profit-maximizing N input was 82 kg/ha in Tanzania, but it was much lower in Uganda (24 kg/ha) mostly because of less favorable prices. The profit-maximizing N input was above the reported N input for 95% of the households in Tanzania and for 43% of the households in Uganda. It was predicted to increase the food availability ratio of food insecure maize growers by 95% in Tanzania, and by 25% in Uganda. The administrative regions where maize supply could increase most were not the same as the regions where the increase in household-level food security was largest. With increased fertilization, food insecure maize growing households (35% in Tanzania and 42% in Uganda) could only contribute about 20% of the overall increase in maize supply, whereas the 20 to 30% food secure households that have a larger area planted with maize could contribute >60%. Our study makes two key contributions: i) a substantial increase in national maize supply is more likely to come from already food secure households with relatively large farms, while food insecure households with small farms may nevertheless increase their household-level food security through maize intensification, and ii) high potential areas to increase maize domestic production do not necessarily match with areas where there is immediate scope to improve household-level food security. [Display omitted] • Food security analysis with current and profit-maximizing N input in East Africa • Food secure households are main contributors of national increase in grain supply • Food insecure households also benefit for their food security • Variations in maize and fertilizer price impact strongly opportunities to reduce food insecurity [ABSTRACT FROM AUTHOR]