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Potato (Solanum tuberosum) is an important staple crop in China, however, potato yields are low, and thus a general aim is to produce more crop with fewer resources and minimal environmental effects. This study aimed to assess the relationships between yield, resource use efficiencies, and environmental performance of potato production in China. Three major potato production regions (Inner Mongolia, Gansu, and Heilongjiang) were surveyed. The current production performance was evaluated, and the scope for improvement was assessed based on a lower and upper target for yield (financial breakeven point and 85% of the potential yield, respectively), water productivity (upper target is 85% of the potential water productivity), nitrogen use efficiency (50 and 90%) and nitrogen surplus (upper target is 80 kg ha−1). Long-term situations were evaluated to identify the target values of nitrogen use efficiency and nitrogen surplus based on currently available technologies. The results indicate that in the short-term nitrogen fertilizer input can be reduced by allowing for soil nitrogen mining to improve the nitrogen use efficiency and reduce nitrogen surplus. Water productivity can be increased by enhancing yield, and water surplus can be reduced by more efficient management of irrigation and rainfall water. In the long-term, with good agronomy, we assess it is feasible to improve yield (from 33–43 to 46–57 t FM ha−1), improve nitrogen use efficiency (to 84%), and reduce nitrogen surplus (from 50–156 to 16–34 kg N ha−1) simultaneously. The latter should be validated experimentally.

Agricultural production in Ghana should more than double to fulfil the estimated food demand in 2050, but this is a challenge as the productivity of food crops has been low, extremely variable and prone to stagnation. Yield gap estimations and explanations can help to identify the potential for intensification on existing agricultural land. However, to date most yield gap analyses had a disciplinary focus. The objective of this paper is to assess the impact of crop management, soil and household factors on maize (Zea mays) yields in two major maize growing regions in Ghana through an integrated approach. We applied a variety of complementary methods to study sites in the Brong Ahafo and Northern region. Farm household surveys, yield measurements and soil sampling were undertaken in 2015 and 2016. Water-limited potential yield (Y w ) was estimated with a crop growth simulation model, and two different on-farm demonstration experiments were carried out in 2016 and 2017. There is great potential to increase maize yields across the study sites. Estimated yield gaps ranged between 3.8 Mg ha −1 (67% of Y w ) and 13.6 Mg ha −1 (84% of Y w ). However, there was no consistency in factors affecting maize yield and yield gaps when using complementary methods. Demonstration experiments showed the potential of improved varieties, fertilizers and improved planting densities, with yields up to 9 Mg ha −1 . This was not confirmed in the analysis of the household surveys, as the large yield variation across years on the same farms impeded the disclosure of effects of management, soil and household factors. The low-input nature of the farming system and the incidence of fall armyworm led to relatively uniform and low yields across the entire population. So, farmers’ yields were determined by interacting, and strongly varying, household, soil and management factors. We found that for highly variable and complex smallholder farming systems there is a danger in drawing oversimplified co

Cropping is responsible for substantial emissions of greenhouse gasses (GHGs) worldwide through the use of fertilizers and through expansion of agricultural land and associated carbon losses. Especially in sub-Saharan Africa (SSA), GHG emissions from these processes might increase steeply in coming decades, due to tripling demand for food until 2050 to match the steep population growth. This study assesses the impact of achieving cereal self-sufficiency by the year 2050 for 10 SSA countries on GHG emissions related to different scenarios of increasing cereal production, ranging from intensifying production to agricultural area expansion. We also assessed different nutrient management variants in the intensification. Our analysis revealed that irrespective of intensification or extensification, GHG emissions of the 10 countries jointly are at least 50% higher in 2050 than in 2015. Intensification will come, depending on the nutrient use efficiency achieved, with large increases in nutrient inputs and associated GHG emissions. However, matching food demand through conversion of forest and grasslands to cereal area likely results in much higher GHG emissions. Moreover, many countries lack enough suitable land for cereal expansion to match food demand. In addition, we analysed the uncertainty in our GHG estimates and found that it is caused primarily by uncertainty in the IPCC Tier 1 coefficient for direct N2O emissions, and by the agronomic nitrogen use efficiency (N-AE). In conclusion, intensification scenarios are clearly superior to expansion scenarios in terms of climate change mitigation, but only if current N-AE is increased to levels commonly achieved in, for example, the United States, and which have been demonstrated to be feasible in some locations in SSA. As such, intensifying cereal production with good agronomy and nutrient management is essential to moderate inevitable increases in GHG emissions. Sustainably increasing crop production in SSA is therefore

Intercropping is an ancient agricultural practice that provides a possible pathway for sustainable increases in crop yields. Here, we determine how competition with wheat affects nutrient uptake (nitrogen and phosphorus) and leaf traits, such as photosynthetic rate, in maize. In a field experiment, maize was planted as a sole crop, in three different intercrop configurations with wheat (a replacement intercrop and two add-row intercrops), and as a skip-row system with one out of each three maize rows omitted. Nitrogen and phosphorus uptake were determined at flowering and maturity. Specific leaf area, leaf nitrogen concentration, chlorophyll content and photosynthetic rate of the ear leaf were determined at flowering. Nitrogen and phosphorus concentrations were significantly lower in intercropped maize than in sole maize and skip-row maize at flowering, but these differences were smaller at maturity. At flowering, specific leaf area was significantly greater in intercrops than in skip-row maize. Leaf nitrogen concentration was significantly lower in add-row intercrops than in sole maize, skip-row maize or maize in the replacement intercrop. Leaf chlorophyll content was highest in sole and skip-row maize, intermediate in maize in the replacement intercrop and lowest in maize grown in add-row intercrops. On the contrary, photosynthetic rate was significantly higher in the replacement intercrop than in sole maize, skip-row maize and the intercrop with an additional maize row. The findings indicate that competition with intercropped wheat severely constrained nutrient uptake in maize, while photosynthetic rate of the ear leaf was not negatively affected. Possible mechanisms for higher photosynthesis rate at lower leaf nitrogen content in intercropped maize are discussed.

Understanding the opportunities for sustainable intensification requires an integrated assessment at field, farm and regional levels of past developments. Two hypotheses regarding current rice production in Central Luzon (Philippines) were developed for this purpose. First, we hypothesize that there are trade-offs between rice yields, labour productivity, gross margin and N use efficiency and, second, that farm(er) characteristics and socio-economic conditions at farm and regional level affect the management practices used by farmers. These hypotheses were tested using two household surveys characterizing rice-based farming systems in Central Luzon in terms of changes over time (1966–2012) and spatial variability. Over the past half-century there was an increase in the proportion of irrigated fields and adoption of improved varieties, which allowed the cultivation of a dry season rice crop in Central Luzon. Moreover, transplanting has been replaced by direct-seeding and herbicides substituted hand-weeding. These resulted in greater rice yields and labour productivity, and contributed to gradual transition from subsistence to commercial farming systems, as observed in the increasing proportion of hired labour and rice sold. Our results indicate the existence of a trade-off between rice yields, labour productivity and N use efficiency as yield levels maximising labour productivity and N use efficiency were ca. 25% and 35% lower than climatic potential yield in the wet and dry season, respectively. At field level, this can be explained by 1) the use of transplanting as crop establishment method, which resulted into higher yields but lower labour productivity as compared to direct-seeding, and 2) the high N application levels, which led to higher yields but lower N use efficiency. In contrast, yield levels which maximised gross margin were ca. 80% of the climatic potential in both wet and dry seasons, so there was little trade-off between rice yields and economic perfor

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 (Yw) and yield gaps (Yg) for major grain legume crops in E-Afr, and (ii) estimate how narrowing the current legume Yg 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 Yw, actual on-farm yield (Ya), and Yg from local to regional scale. Future legume self-sufficiency was assessed for 2050 demand assuming different Yg closure scenarios. On average, Ya was 25% of Yw across all legume-county combinations, being 15% for Kenya, 23% for Tanzania and 41% for Ethiopia. On average, common bean had the largest Yg of 2.6 Mg ha−1and chickpea the smallest (1.4 Mg ha−1). Closure of the exploitable Yg (i.e., 80% of Yw) can help to meet future legume demand in both Kenya and Tanzania, while it seems not to be sufficient in Ethiopia.

Europe accounts for around 20% of the global cereal production and is a net exporter of ca. 15% of that production. Increasing global demand for cereals justifies questions as to where and by how much Europe's production can be increased to meet future global market demands, and how much additional nitrogen (N) crops would require. The latter is important as environmental concern and legislation are equally important as production aims in Europe. Here, we used a country-by-country, bottom-up approach to establish statistical estimates of actual grain yield, and compare these to modelled estimates of potential yields for either irrigated or rainfed conditions. In this way, we identified the yield gaps and the opportunities for increased cereal production for wheat, barley and maize, which represent 90% of the cereals grown in Europe. The combined mean annual yield gap of wheat, barley, maize was 239 Mt, or 42% of the yield potential. The national yield gaps ranged between 10 and 70%, with small gaps in many north-western European countries, and large gaps in eastern and south-western Europe. Yield gaps for rainfed and irrigated maize were consistently lower than those of wheat and barley. If the yield gaps of maize, wheat and barley would be reduced from 42% to 20% of potential yields, this would increase annual cereal production by 128 Mt (39%). Potential for higher cereal production exists predominantly in Eastern Europe, and half of Europe's potential increase is located in Ukraine, Romania and Poland. Unlocking the identified potential for production growth requires a substantial increase of the crop N uptake of 4.8 Mt. Across Europe, the average N uptake gaps, to achieve 80% of the yield potential, were 87, 77 and 43 kg N ha−1 for wheat, barley and maize, respectively. Emphasis on increasing the N use efficiency is necessary to minimize the need for additional N inputs. Whether yield gap reduction is desirable and feasible is a matter of balancing Europe's role

Non-PR, IFPRI5; CRP2; CRP7; Global Futures and Strategic Foresight, EPTD; PIM, 8 pages, CGIAR Research Program on Policies, Institutions, and Markets (PIM); CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS), Producing adequate food to meet global demand by 2050 is widely recognized as a major challenge, particularly for sub-Saharan Africa (SSA) (Godfray et al. 2010; Alexandratos and Bruinsma 2012; van Ittersum et al. 2016). Increased price volatility of major food crops (Koning et al. 2008; Lagi et al. 2011), an abrupt surge in land area devoted to crop production in recent years (Grassini et al. 2013) and extensive labour force mobilization (NEPAD 2013) reflect the powerful forces underpinning this challenge to increase production. The 2008 price spikes triggered the Food and Agriculture Organization of the United Nations (FAO) and the World Food Programme (WFP) to issue warnings, noting the 60–70 percent increase in food production by 2050 that will be needed to meet the escalating food demand for the expected 9.7 billion global population. In this policy brief we focus on the feasibility to meet such increase by 2050 with scenarios of population increase and dietary changes under current climate conditions. Current climate variability is very high in sub-Saharan Africa causing significant yield variations across years (e.g., Shiferaw et al. 2014; www.yieldgap.org). Climate change will further add to the food production challenge (Porter et al. 2014; Vermeulen et al. 2012; McKersie 2015). Smallholder farmers will need to adapt to a changing climate while at the same time they are expected to increase production in such way that it has a minimum effect on the drivers of climate change, i.e. mitigating greenhouse gas emissions.

The Global Yield Gap Atlas project (GYGA - http://yieldgap.org) has undertaken a yield gap assessment following the protocol recommended by van Ittersum et al. (2013). One part of the activities consists of collecting and processing weather data as an input for crop simulation models in sub-Saharan African countries including Kenya. This publication covers daily weather data for 12 locations in Kenya for the years 1998-2012. The project looked for good quality weather data in areas where crops are pre-dominantly grown. As locations with good public weather data are sparse in Africa, the project developed a method to generate bias corrected weather data from a combination of observed data and other external weather data. The bias corrected weather data consist of daily TRMM rain data and NASA POWER Tmax, Tmin, and Tdew data. These data are corrected based on calibrations with short-term (<10 years) observed weather data.

Non-PR, IFPRI2; CRP2; CRP7, EPTD; PIM, CGIAR Research Program on Policies, Institutions, and Markets (PIM); CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS), Producing adequate food to meet global demand by 2050 is widely recognized as a major challenge, particularly for Africa south of the Sahara, including Tanzania (Godfray et al. 2010; Alexandratos and Bruinsma 2012; van Ittersum et al. 2016). Increased price volatility of major food crops (Koning et al. 2008; Lagi et al. 2011) and an abrupt surge in land area devoted to crop production in recent years (Grassini et al. 2013) reflect the powerful forces underpinning this challenge. The 2008 price spikes triggered the Food and Agriculture Organization and the World Food Programme to issue warnings and call for a 60–70 percent increase in food production by 2050 to meet the escalating food demand for the expected 9.7 billion global population.

Although global food demand is expected to increase 60% by 2050 compared with 2005/2007, the rise will be much greater in sub-Saharan Africa (SSA). Indeed, SSA is the region at greatest food security risk because by 2050 its population will increase 2.5-fold and demand for cereals approximately triple, whereas current levels of cereal consumption already depend on substantial imports. At issue is whether SSA can meet this vast increase in cereal demand without greater reliance on cereal imports or major expansion of agricultural area and associated biodiversity loss and greenhouse gas emissions. Recent studies indicate that the global increase in food demand by 2050 can be met through closing the gap between current farm yield and yield potential on existing cropland. Here, however, we estimate it will not be feasible to meet future SSA cereal demand on existing production area by yield gap closure alone. Our agronomically robust yield gap analysis for 10 countries in SSA using location-specific data and a spatial upscaling approach reveals that, in addition to yield gap closure, other more complex and uncertain components of intensification are also needed, i.e., increasing cropping intensity (the number of crops grown per 12 mo on the same field) and sustainable expansion of irrigated production area. If intensification is not successful and massive cropland land expansion is to be avoided, SSA will depend much more on imports of cereals than it does today.

PR, IFPRI3; CRP2; CRP7; A Ensuring Sustainable food production; DCA; ISI, EPTD; PIM, CGIAR Research Program on Policies, Institutions, and Markets (PIM); CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS)