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Agriculture is facing the complex challenge of satisfying increasing food demands, despite the current and projected negative impacts of climate change on yields. Increasing crop diversity at a national scale has been suggested as an adaptive measure to better cope with negative climate impacts such as increasing temperatures and drought, but there is little evidence to support this hypothesis at the field scale. Using seven long-term experiments across a wide latitudinal gradient in Europe, we showed that growing multiple crop species in a rotation always provided higher yields for both winter and spring cereals (average +860 and +390 kg ha−1 per year, respectively) compared with a continuous monoculture. In particular, yield gains in diverse rotations were higher in years with high temperatures and scant precipitations, i.e. conditions expected to become more frequent in the future, rendering up to c. 1000 kg ha−1 per year compared to monocultures. Winter cereals yielded more in diverse rotations immediately after initiation of the experiment and kept this advantage constant over time. For spring cereals, the yield gain increased over time since diversification adoption, arriving to a yearly surplus of c. 500 kg ha−1 after 50–60 years with still no sign of plateauing. Diversified rotations emerge as a promising way to adapt temperate cropping systems and contribute to food security under a changing climate. However, novel policies need to be implemented and investments made to give means and opportunities for farmers to adopt diversified crop rotations.

To evaluate the effects of repeated sewage sludge applications in comparison to mineral fertilisers on a winter wheat - maize - sugar beet rotation, a field experiment on a silty-loam soil, in the eastern Po Valley (Italy), was carried out since 1988. Municipal-industrial wastewater sludge as anaerobically-digested, belt filtered (dewatered), and composted with wheat straw, has been applied at 5 and 10 Mg DM ha-1yr-1.. Biosolids gave crop yields similar to the highest mineral fertiliser dressing. However, with the higher rate of liquid and dewatered sludges, excessive N supply was harmful, leading to wheat lodging and poor quality of sugar beet and wheat crops. From this standpoint compost use was safer. Biosolids increased organic matter (OM), total N, and available P in the soil and reduced soil alkalinity, with more evident effects at the highest rate. Compost caused the most pronounced OM topsoil accumulation. Significant accumulations of total Zn and Cu were detected in amended topsoil, but no other heavy metals (Cd, Cr, Ni, Pb), whose total concentration remained well below the hazard limits. Biosolid applications significantly increased the content of N, P, Zn, and Cu in wheat grain, N and Cu in sugar beet roots, and only Cu in maize grain. Although, the application of biosolids brought about notable benefits to soil fertility, it is associated with possible negative effects on water quality due to increased P availability and on soil ecology due to Zn accumulation.

The abstract, relative to a poster presented at a meeting in the Rothamsted Exp. Stn., discuss the possibility to increase CO2 soil sequestration through better crop rotations under different ferilization regimes