We consider that here are four key issues and priorities for hydrological sciences in respect to sidement, phosphorus and colloid transfers from intensive grasslands (Table I). These are inadequate inventories, analytical challenges, the neglected role of organic matter and challenges for modelling and integration. We need to change the way in which grassland systems are perceived and monitored; this commentary and the ones that follow may help start to achieve this. There is also a critical requirement for a wider acceptance of a 'continuum' of sediment and particles and processes from molecular to >1 μm, including clarity with operational definitions and an acceptance of the strenghts and weakness of analytical tools. A variety of new tracer techniques are avaliable for helping assess the role of organic matter in contributing to transfers and these must be applied. Field scientists must fully appreciate the variability of observations, and modellers need to understand the uncertainty in model processes and model outputs. Overall, however, the critical message is that integrated inter-disciplinary team working is encourage, discipline polarization is discourage because it undermines progress. To that end, in the assembly of commentaries that follow (Bilotta et al., 2007; Gimbert et al., 2007; Granger et al.; 2007; Krueger et al., 2007) we are presenting ideas as part of an integrated project team that is attempting to improve our knowledge and ability to model sediment, colloids and phosphorus losses from intensive grassland, with - we hope - some wider generic relevance for the hydrological community.