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We investigated the role of labour in explaining the yield gap of cereals at both crop and farm levels on smallholder farms in Southern Ethiopia. A household survey containing detailed information of labour use at crop and farm level of ca. 100 farms in a maize-based system around Hawassa and ca. 100 farms in a wheat-based system around Asella was used for this purpose. Stochastic frontier analysis was combined with the principles of production ecology to decompose maize and wheat yield gaps. Actual maize and wheat yields were on average 1.6 and 2.6 t ha−1, respectively, which correspond to 23 and 26% of the water-limited yield (Yw) of each crop. For both crops, nearly half of the yield gap was attributed to the technology yield gap, indicating sub-optimal crop management to achieve Yw even for the farmers with the highest yields. The efficiency yield gap was ca. 20% of Yw for both crops; it was negatively associated with sowing date and with the proportion of women's labour used for sowing in the case of maize but with the proportion of hired labour used for sowing and weed control in the case of wheat. The resource yield gap was less than 10% of Yw for both crops due to small differences in input use between highest- and lowest-yielding farms. The contribution of capital and farm power availability to crop yields, input use and labour use was analysed at the farm level. Labour calendars showed that crops cultivated in Hawassa were complementary, with peak labour occurring at different times of the year. By contrast, crops cultivated in Asella competed strongly for labour during sowing, hand-weeding and harvesting months, resulting in potential trade-offs at farm level. Oxen ownership was associated with capital availability, but not farm power in Hawassa and with both capital availability and farm power in Asella. Farmers with more oxen applied more nitrogen (N) to maize in Hawassa and cultivated more land in Asella, which is indicative of an intensification pathway in the former and an extensification pathway in the latter. Differences in land:labour ratio and in the types of crops cultivated explained the different strategies used in the two sites. In both sites, although gross margin per unit area increased linearly with increasing crop yield and farm N productivity, gross margin per labour unit increased up to an optimal level of crop yield and farm N productivity after which no further response was observed. This suggests that narrowing the yield gap may not be economically rational in terms of labour productivity. We conclude that labour (and farm power) is not a major determinant of maize yield gaps in Hawassa, but is a major determinant of wheat yield gaps in Asella.

Environmental pressures posed through human activities are expected to further increase due to growing population numbers and increasing per capita consumption. It will be crucial that the sum of all pressures leaves the planet within sustainability thresholds. The huge challenge for agriculture is to double its food production without further deteriorating the environment, but there is little consensus on how to do this. At the global scale, ‘sustainable intensification’ is seen as an important strategy. At best, intensification improves the utilization of resources, but it also increases emissions per ha and may go hand in hand with specialisation, increases in the scale of farming and regional concentration. A typical example of a sector characterised by intensification, scale enlargement and regional concentration is the Dutch livestock sector. To consolidate and strengthen the Dutch position as second agricultural exporter in the world, this process is still continuing, linked with constant efforts to further improve economic and environmental efficiencies through farm size enlargement and adoption of additional technologies. However, the industrial and inherently resource-intensive character of this livestock production leaves numerous sustainability issues unaddressed, provoking new questions and controversy in Dutch society. Sound policies start with the acknowledgement of trade-offs between population size, food consumption patterns and land spared for nature. Therefore, a legitimate, but seldom asked question is which part of the total effort needed to feed the human population should be on more production and which part on limiting population growth, changing human diets and global redistribution of wealth.

In the last few decades, significant changes in livestock farming systems and land use were observed in European mountain areas with large implications for the sustainability of grazing agro-ecosystems. System dynamic studies become essential to understand these changes, identify the drivers involved and trying to anticipate what might happen in the future. The objectives of this study were as follows: (i) to analyse the main recent changes that occurred in mountain cattle farming in the Spanish Pyrenees; (ii) to typify diverse trajectories of evolution of these systems; and (iii) to establish drivers of change that might help understand the evolution of mountain agriculture. A constant sample of mountain cattle farms was analysed for the period 1990 to 2004. In total, 30% of farms have disappeared during this time interval. For the remaining farms, the most important general changes observed were as follows: increment of size; change of productive orientation from mixed beef-dairy to pure beef production; extensification of grazing management; reduction of family labour and increase of pluriactivity; reduction of unitary variable costs; and increase of labour productivity. After the elimination of common temporal effects between dates, multivariate techniques allowed for the identification of three patterns and six specific trajectories of evolution that are profiled in the text. Relationships between the patterns of evolution and other variables referring the farm, the household and the socio-economic environment were identified as drivers of change: (i) the specific location of the farm in relation to the capital village of the municipality and the evolution other sectors of the economy, in particular tourism; (ii) the size of the family labour, presence of successors and degree of dynamism of the farmer; and (iii) the initial orientation of production.