No-till in northern, western and south-western Europe: a review of problems and opportunities for crop production and the environment

Recent literature on no-till is reviewed with particular emphasis on research on commercial uptake and environmental concerns in northern, western and south-western Europe. Increased interest in no-till, and minimum or reduced tillage, results from changes in the economic circumstances of crop production, the opportunity to increase the area of more profitable autumn-sown crops and increased concern about environmental damage associated with soil inversion by ploughing. Highly contrasting soil and climate types within and between these regions exert a strong influence on the success of no-till. While no-till may often result in crop yields which equal or exceed those obtained after ploughing, modest reductions in yield may be tolerated if production costs are lower than with ploughing. The relative costs of fuel and herbicides have changed appreciably in recent years making no-till more attractive commercially. While effective weed control is an essential aspect of no-till, current herbicide technology may not yet fully achieve this. In northern regions no-till usually allows earlier drilling of winter-sown crops but will give lower soil temperature and higher moisture content in spring, causing delayed drilling of spring-sown crops. No-till soils have greater bulk density and bearing capacity than ploughed soils with a pronounced vertical orientation of macroporosity allowing penetration of roots and water, especially in view of the increased population of deep-burrowing earthworms. Particular care must be taken with no-till to minimise soil damage at harvest and to ensure the even distribution of crop residues prior to drilling. Reduced erosion and runoff after adoption of no-till are widely observed and are of particular importance in southwestern Europe. No-till reduces losses of phosphorus in runoff and, in some cases, reduces the loss of nitrate through leaching. Emissions of greenhouse gases CO2 and N2O from no-till soils are highly variable and depend on complex interactions of soil properties. Emission of CO2 from fuel during machinery usage is always appreciably reduced with no-till. Increased soil organic carbon in surface layers of no-till soils is widely found but may not be associated with increased carbon sequestration throughout the profile. The evaluation of the relative carbon balance for no-till and ploughing depends upon complex inter-relationships between soil and climate factors which are as yet poorly understood. Adoption of no-till could be encouraged by government financial assistance in recognition of environmental benefits, although future restrictions on the use of herbicides may be a deterrent. Opportunities for further research on no-till are outlined. 2

Mitigation Measures for Water Pollution and Flooding

This chapter discusses the range of measures that can be used to mitigate the impacts of water pollution and flooding. It makes a distinction between source measures which aim to reduce the amount of water or pollutant initially mobilised, pathway interventions which seek to slow the flow of pollutant enriched water once it has become mobilised and methods to protect receptor water bodies which are intended to reduce peak flows or prevent pollutants moving further through a catchment. In many European countries the policies and programmes used to increase the adoption of such measures are heavily influenced by EU obligations stemming from the Floods, Nitrates and Water Framework Directives. Typical approaches used involve a combination of regulation, financial incentives and advice provision. There are also a range of tools that can be used to model the potential effects of mitigation measures and a number of research programmes generating findings that may be of value to the landscape planner