Impact of hydrology and effluent quality on the management of woodchip pads for overwintering cattle. I. Development of monitoring methodology and sampling strategies

(Received27June2011;revised24November2011;accepted16March2012;firstpublishedonline12April2012)SUMMARYWoodchip pads can be a sustainable alternative to the overwintering of stock on grassland or in conventionalhousing and can offer benefits in improved animal performance, improved health and environmentallysustainable options for the management of animal excreta (dung, urine and the resulting effluent). Novel flowmeasuring equipment was developed to monitor effluent drainage from twowoodchip pads sited on commercialfarmsintheUK,oneinPowys(Wales,UK)andtheotherinLeicestershire(England,UK).Observationsweremadeover 8 months in 2009/10. The aim was to assess both hydrological characteristics and nutrient fluxes. Flowmonitoring, based on the use of tipping bucket or the principles of an overshot water wheel, was required to becapable of diverting a sample into a storage tank for sub-sampling and subsequent analysis. Estimates of padoutputs through evaporation and sub-surface drainage accounted for 0·98–1·01 of total inputs from precipitationand animal excreta, with evaporation and pad drainage representing 0·47–0·63 and 0·34–0·51 of total inputs,respectively. The resulting scientific information is of value in the synthesis of guidelines for design, constructionand management of woodchip pads. Detailed analysis of flow and precipitation data, coupled with columnabsorptionstudiestoevaluatemoistureretentioninthewoodchipmatrix,wereusedtoconsiderthe developmentof modelling approaches, with the potential to predict drainage outputs across a range of geographical, weatherand pad management situations.INTRODUCTIONThereiscontinuedinterestintheuseofwoodchippads(P.FrenchM CREH 2005; Vinten et al. 2006).