b'Thomas DoyleBallyoughterTom Doyle farms 45 hectares in north Co. Wexford with his wife, Alice. The farm is locatedbeside the village of Ballyoughter, where the main enterprise is beef farming, using a grazing grass based production system. Typically, Tom buys in just over 100 yearling or store cattle during the winter months, rears and sells them as finished cattle to the factory when close to two years of age. The farm stocking rate under two livestock units per hectare (135 kg N/Ha.) and no suckler cows are kept on the farm. Usually there is a cereal crop on the farm, with 8 hectares of Winter Barley grown this year.The soil type on the farm is a surface water gley, with soils that are naturally moderate to poor draining. The soil test results for the farm in 2017 are typical of the area, with low levels forP (average 3.5 mg/l) and medium to high for K (average 120 mg/l). Tom has managed the soilpH well, with an average value of 6.4Tom has and continues to be a very active member of various farm organisations, of note being chairman of both the IFAs national Farm Business Committee and the Wexford FarmersCo-operative Society.Grassland phosphorus plot trialPhosphorus (P) is an essential nutrient input to agricultural systems for grassland and cropproduction. Excess P (if lost to waterbodies) can contribute to eutrophication and decline inWater Framework Directive (WFD) status (ONeil et al., 2012; Dodds and Smith, 2016).In Ireland, 26% of rivers still have an average P concentration over 0.035 mg l-1 indicating a failure to achieve good ecological status under the WFD criteria (WFD indicator report, EPA). Under the Food Wise 2025 plan (2015) Ireland aims to increase the value of primary production by 65% between 2015 and 2025. This will require expansion of the national dairy herd andconsequently, will increase the volume of cattle slurry produced. Achieving both of theseenvironmental and agronomic goals requires prioritization of P management including betterfundamental understanding of soil and water chemistry, improved utilization of slurry fertilizers on farm, and tailoring of nutrient recommendations to reflect plant requirements andenvironmental risks.Considering the increasing availability of manure P resources on Irish farms, the aim of this study was to evaluate agronomic impact and potential losses of P across soil types and fertilisertreatments. The specific objectives were to compare the effects of organic and inorganicfertiliser applications (1) on grass production (2) grass P concentration (3) soil P build-up and(4) to quantify P losses below the root zone across contrasting soil types. Material and methods:This study utilizes grassland sites in four contrasting catchments. Presented herein is theBallycanew catchment; a poorly drained, grassland site in Co. Wexford in the Southeast ofIreland. The experimental design consists of 28 plots per site (Figure 1), receiving treatments of either chemical or cattle slurry P. 87'