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.

► In spite of extensive research on no-till in northern Europe uptake by farmers is negligible. ► In southern Europe improved soil and water conservation are increasing uptake of no-till. ► Environmental benefits from no-till, especially net climate forcing, need further evaluation. ► Weed control is critical with no-till, especially if restrictions in herbicide use are introduced. ► Greater practical understanding and financial assistance would increase the uptake of no-till.