• A comparison of SWAT, HSPF and SHETRAN/GOPC for modelling phosphorus export from three catchments in Ireland

      Nasr, Ahmed Elssidig; Bruen, Michael; Jordan, Philip; Moles, Richard; Kiely, Gerard; Byrne, Paul; Environmental Protection Agency; Teagasc; Teagasc (Elsevier, 02/07/2012)
      Recent extensive water quality surveys in Ireland revealed that diffuse phosphorus (P) pollution originating from agricultural land and transported by runoff and subsurface flows is the primary cause of the deterioration of surface water quality. P transport from land to water can be described by mathematical models that vary in modelling approach, complexity and scale (plot, field and catchment). Here, three mathematical models (SWAT, HSPF and SHETRAN/GOPC) of diffuse P pollution have been tested in three Irish catchments to explore their suitability in Irish conditions for future use in implementing the European Water Framework Directive. After calibrating the models, their daily flows and total phosphorus (TP) exports are compared and assessed. The HSPF model was the best at simulating the mean daily discharge while SWAT gave the best calibration results for daily TP loads. Annual TP exports for the three models and for two empirical models were compared with measured data. No single model is consistently better in estimating the annual TP export for all three catchments.
    • Assessing the Impact of Pollen-mediated Gene Flow from GM Herbicide Tolerant Brassica Napus into Common Wild Relatives in Ireland

      Collier, Marcus J.; Mullins, Ewen; Environmental Protection Agency; Teagasc; ERTDI 2006-B-MS-46; 2007-B-DS-1-S1 (Royal Irish Academy, 30/04/2012)
      Although now we have had many years of research completed on assessing the potential environmental impact of GM crops, concern remains over their potential impact on biodiversity in the rural landscape. In particular, issues have arisen in regards to the modification of crops with traits that could introgress into sexually compatible wild relatives. In contrast to wheat, barley, potato and maize, Brassica napus (oilseed rape) is the only commercial crop grown in Ireland at present with the potential to successfully transfer its DNA, via pollen-mediated gene flow, into inter-related weed species. This review details the species in question and by examining the relevant literature that relates to Irish agronomic conditions, demonstrates that gene flow is likely to occur, especially to an earlier used cultivar, Brassica rapa. However, the critical factor remains not that GM traits will flow from the commercial source but what might the consequences of said gene flow events be. This review indicates that the conferred trait in question (in this case, herbicide tolerance) can only impact on weed diversity in the presence of selecting herbicide action. In the absence of the herbicide, the GM traits will be lost from the wild species over time and will not confer any selective advantage that could facilitate population growth.
    • Clay illuviation provides a long-term sink for C sequestration in subsoils

      Torres-Sallan, Gemma; Schulte, Rogier P.; Lanigan, Gary; Byrne, Kenneth; Reidy, Brian; Simó, Iolanda; Six, Johan; Creamer, Rachel; Irish Soil Information System project; Teagasc; et al. (Springer Nature, 2017-04-06)
      Soil plays a key role in the global carbon (C) cycle. Most current assessments of SOC stocks and the guidelines given by Intergovernmental Panel on Climate Change (IPCC) focus on the top 30 cm of soil. Our research shows that, when considering only total quantities, most of the SOC stocks are found in this top layer. However, not all forms of SOC are equally valuable as long-term stable stores of carbon: the majority of SOC is available for mineralisation and can potentially be re-emitted to the atmosphere. SOC associated with micro-aggregates and silt plus clay fractions is more stable and therefore represents a long-term carbon store. Our research shows that most of this stable carbon is located at depths below 30 cm (42% of subsoil SOC is located in microaggregates and silt and clay, compared to 16% in the topsoil), specifically in soils that are subject to clay illuviation. This has implications for land management decisions in temperate grassland regions, defining the trade-offs between primary productivity and C emissions in clay-illuviated soils, as a result of drainage. Therefore, climate smart land management should consider the balance between SOC stabilisation in topsoils for productivity versus sequestration in subsoils for climate mitigation.
    • Comparison of physically based catchment models for estimating Phosphorus losses

      Nasr, Ahmed Elssidig; Bruen, Michael; Environmental Protection Agency; Teagasc (IWA publishing, 02/07/2012)
      As part of a large EPA-funded research project, coordinated by TEAGASC, the Centre for Water Resources Research at UCD reviewed the available distributed physically based catchment models with a potential for use in estimating phosphorous losses for use in implementing the Water Framework Directive. Three models, representative of different levels of approach and complexity, were chosen and were implemented for a number of Irish catchments. This paper reports on (i) the lessons and experience gained in implementing these models, (ii) compares the performances of the individual models and (iii) assesses their sensitivities to the main parameters and to spatial scales.
    • Developing an independent, generic, phosphorus modelling component for use with grid-oriented, physically-based distributed catchment models

      Nasr, Ahmed Elssidig; Taskinen, Antti; Bruen, Michael; Environmental Protection Agency; Teagasc (02/07/2012)
      Grid-oriented, physically based catchment models calculate fields of various hydrological variables relevant to phosphorous detachment and transport. These include (i) for surface transport: overland flow depth and flow in the coordinate directions, sediment load, and sediment concentration and (ii) for subsurface transport: soil moisture and hydraulic head at various depths in the soil. These variables can be considered as decoupled from any chemical phosphorous model since phosphorous concentrations, either as dissolved or particulate, do not influence the model calculations of the hydrological fields. Thus the phosphorous concentration calculations can be carried out independently from and after the hydrological calculations. This makes it possible to produce a separate phosphorous modelling component which takes as input the hydrological fields produced by the catchment model and which calculates, at each step the phosphorous concentrations in the flows. This paper summarise the equations and structure of Grid Oriented Phosphorous Component (GOPC) developed for simulating the phosphorus concentrations and loads using the outputs of a fully distributed physical based hydrological model. Also the GOPC performance is illustrated by am example of an experimental catchment (created by the author) subjected to some ideal conditions.
    • Digital Soil Information System for Ireland – Scoping Study

      Daly, Karen M.; Fealy, Reamonn; Environmental Protection Agency (Environmental Protection Agency, 01/09/2007)
      Soil is our life support system, crucial for the production of food and biomass and critical for the sustainability of an agro–environmental economy. The authors suggest that it is axiomatic that Ireland should have ready access to its soil information through the benefits of modern information technology. Soil is a multifunctional and complex natural medium that provides ecosystem services such as the production of food, fibre and fuel, the provision of habitat, nutrient cycling, contaminant transformation, water cycling and climate regulation. Reports from the European Commission indicate that many of these functions and services are under threat and soil protection is now placed on the same level as that of water and air.
    • Digital Soil Mapping in the Irish Soil Information System

      Corstanje, R.; Mayr, T.; Fealy, Reamonn; Zawadzka, Joanna; Lopapa, G.; Creamer, Rachel E.; Schulte, Rogier P.; Environmental Protection Agency (International Union of Soil Sciences, 2009-12)
      Harmonised soil data across Europe with a 1:250 000 geo-referenced soil database will allow for exchange of data across member states and the provide the information needed by the European Commission and European Environment Agency for reporting on issues relating to soil quality under a fu-ture Soil Framework Directive. Within this context, the Environmental Protection Agency of the Republic of Ireland commissioned a project run by Teagasc to produce a 1:250 000 soil map of the Republic of Ire-land. Delivery of this map and associated database is a collaborative effort between Teagasc, the National Soil Resources Institute at Cranfield in the UK and University College Dublin.
    • Effect of Agricultural Practices on Nitrate Leaching

      Ryan, Michael; McNamara, Kevin; Brophy, C.; Connolly, John; Carton, Owen T.; Richards, Karl G.; Environmental Protection Agency (Teagasc, 01/12/2005)
      A farm-scale study, carried out at Teagasc, Moorepark (Curtin’s farm), examined the effect of four managements (treatments) on nitrate-nitrogen (NO3-N) leaching over the period 2001-`05. Leaching was measured in these treatments: (T1) plots receiving dirty water and N fertilizer which were grazed; (T2) 2-cut silage and grazing plots receiving slurry and fertilizer N; (T3) grazed plots receiving fertilizer N and (T4) 1-cut silage and grazing plots receiving slurry and fertilizer N. The soil is a free-draining sandy loam overlying Karstic fissured limestone. The mean direct N inputs (kg/ha) for T1-T4 in 2001-`04 were 311, 309, 326, 331, respectively, with stocking rates (LU/ha) of 2.12 - ~2.47. Eight ceramic cups per plot, in 3 replicate plots of each treatment, were used to collect water, on a weekly basis, from 1.0 m deep using 50 kPa suction. There were 33, 37, 26 and 24 sampling dates in the 4 years, respectively. The NO3-N and NH4-N concentrations (mg/l) were determined in the water samples. The annual average and weekly concentration of these parameters was statistically analysed for all years, using a repeated measures analysis. The aggregated data were not normally distributed. There was an interaction between treatment and year (p<0.001). Significant differences (p=0.05) in NO3-N concentrations showed between the treatments in years 1, 2, 4 but not in year 3. For the NH4-N data there was no interaction between treatment and year, p=0.12, or main effect of treatment, p=0.54 but there were differences between years, p=0.01. Mean weekly concentrations were analysed separately for each year. For NO3-N, in years 1, 2 and 4 there was an interaction between treatment and week (p<0.001). With NH4-N, there was an interaction between treatment and week in all 4 years. Dirty water was significantly higher than grazed and 1 cut silage in NO3-N concentrations in year 1; in year 2, dirty water and 2 cut silage were significantly higher than the other treatments while in year 4, dirty water and grazed were significantly higher than the other two treatments. The overall four-year weighted mean NO3-N and NH4-N concentrations were 8.2 and 0.297 mg/l. The NCYCLE (UK) model was adapted for Irish conditions as NCYCLE_IRL. The NCYCLE empirical approach proved to be suitable to predict N fluxes from Irish grassland systems in most situations. Experimental data appeared to agree quite well, in most cases, with the outputs from NCYCLE_IRL. The model was not capable of predicting data from some of the leaching experiments, which suggests that the observed leaching phenomena in these experiments could be governed by non-average conditions or other parameters not accounted for in NCYCLE_IRL. An approach that took into account denitrification, leaching and herbage yield would probably explain the differences found. NCYCLE_IRL proved to be a useful tool to analyse N leaching from grazed and cut grassland systems in Ireland.
    • Good water status: The integration of sustainable grassland production and water resources in Ireland

      Richards, Karl G.; Fenton, Owen; Khalil, Mohammed I.; Haria, Atul H.; Humphreys, James; Doody, Donnacha G.; Moles, Richard; Morgan, Ger; Jordan, Philip; Department of Agriculture, Food and the Marine, Ireland; et al. (School of Agriculture, Food Science and Veterinary Medicine, University College Dublin in association with Teagasc, 2009)
      The challenge for sustainable grassland production is to integrate economically profitable farming systems with environmental protection. The Water Framework Directive aims to attain at least “good status” for all waters by 2015, to be achieved through the introduction of measures across all sectors of society. Historically, the impact of grassland agriculture on water quality was investigated in isolation. More recently it has been highlighted that water quality and other environmental impacts such as greenhouse gas emissions must be considered in an integrated manner. Catchment hydrology is critical to understanding the drivers behind nutrient transport to surface water and groundwaters. Flashy catchments are more susceptible to phosphorus, sediment and ammonium loss, whereas contrastingly baseflow dominated catchments are more susceptible to nitrate transport. Understanding catchment hydrology enables the targeting of measures for the mitigation of diffuse agricultural contaminants. This increased understanding can also be used to support extended deadlines for the achievement of good status. This paper reviews the potential effects of grassland agriculture on water quantity and the transport of pesticides and nutrients to water in the context of achieving good status for all waters by 2015 under the Water Framework Directive.
    • The impact of grazing cattle on soil physical properties and nutrient concentrations in overland flow from pasture, Part B

      Kurz, Isabelle; O’Reilly, Conor; Tunney, Hubert; Bourke, David; Environmental Protection Agency (Teagasc, 01/06/2007)
      The loss of nutrients from agricultural land to water bodies is a serious concern in many countries. To gain information on the contribution of grazing animals to diffuse nutrient losses from pasture areas to water, this study looked at the impact of cattle on nutrient concentrations in overland flow and on soil hydrology (bulk density, macroporosity and resistance to penetration). Rainfall simulations to produce overland flow were conducted and soil physical measurements were taken on experimental plots assigned to one of two treatments: 1) cattle had unrestricted access to the plot; 2) cattle could graze the plot but they could neither walk on the plot area nor deposit excrements on it. Areas to which the cattle had free access were characterised by 57%-83% lower macroporosity, by 8%-17% higher bulk density and by 27%-50% higher resistance to penetration than areas from which the cattle were excluded. The nutrients in overland flow from grassland that were affected by the presence of grazing animals were mainly the particulate nitrogen, the organic phosphorus and the potassium concentrations. Overall, the presence of cattle had a longer lasting effect on the soil hydrological parameters measured than on the nutrient concentrations in overland flow.
    • The influence of aggregate size fraction and horizon position on microbial community composition

      Fox, Aaron; Ikoyi, Israel; Torres-Sallan, Gemma; Lanigan, Gary; Schmalenberger, Achim; Wakelin, Steve; Creamer, Rachel; Teagasc Walsh Fellowship Programme; Environmental Protection Agency; Agricultural GHG Research Initiative for Ireland; et al. (Elsevier, 2018-03-09)
      The influence of horizon position and aggregate size on bacterial and fungal community composition was determined. From nine sites, soils were collected from the top three horizon positions (H1, H2 and H3). Physical fractionation separated samples into large macroaggregate (LM, >2000 μm), macroaggregate (MAC, >250 μm), microaggregate (MIC, <250 μm), and silt and clay (SC, 53 μm) fractions. In all samples, the structure of the bacterial and fungal community composition was assessed via restriction fragment length polymorphism (T-RFLP), and for the four aggregate sizes from the top two horizons positions an in-depth analysis of the bacterial community was conducted using next generation sequencing (NGS). Bacterial and fungal communities both differed between aggregate-sizes. Changes in the composition of the bacterial and fungal communities also occurred among horizon positions, with a significant interaction between aggregate size and horizon position evident for the bacterial community. Using NGS, it was shown that aggregate-size had a significant effect on the bacterial community in both horizon positions at both the phyla and family taxonomic levels. MAC and MIC significantly differed in the % relative abundance of bacterial groups, potentially indicating differing predation pressures. These results indicate that both horizon position and aggregate size support distinct microbial communities. Understanding these parameters is critical in our comprehension of the patterns of microbial diversity in soil.
    • An insight into the impact of arable farming on Irish biodiversity: A scarcity of studies hinders a rigorous assessment

      O'Brien, Martin; Spillane, Charles; Meade, Connor; Mullins, Ewen; Environmental Protection Agency; 2006-B-MS-46 (Royal Irish Academy, 27/08/2008)
      To help understand and counteract future agronomic challenges to farmland biodiversity, it is essential to know how present farming practices have affected biodiversity on Irish farms. We present an overview of existing research data and conclusions, describing the impact of crop cultivation on biodiversity on Irish arable farms. An extensive literature review clearly indicates that peer-reviewed publications on research conducted in Ireland on this topic are quite scarce: just 21 papers investigating the effect of conventional crop cultivation on Irish biodiversity have been published within the past 30 years. Principally, these studies have concluded that conventional crop cultivation has had an adverse impact on biodiversity on Irish farms, with 15 of the 21 studies demonstrating negative trends for the taxa investigated. Compared to other EU states, the relative dearth of baseline data and absence of monitoring programmes designed to assess the specific impacts of crop cultivation on Irish biodiversity highlight the need to develop long-term research studies. With many new challenges facing Irish agriculture, a research programme must be initiated to measure current levels of biodiversity on arable land and to assess the main farming ‘pressures’ causing significant biodiversity loss or gains in these systems.
    • The interactive effects of fertiliser nitrogen with dung and urine on nitrous oxide emissions in grassland

      Hyde, Bernard; Forrestal, Patrick J.; Jahangir, Mohammad M. R.; Ryan, Michael; Fanning, A.; Carton, Owen T.; Lanigan, Gary; Richards, Karl G.; Environmental Protection Agency; Department of Agriculture, Food and the Marine, Ireland; et al. (Teagasc (Agriculture and Food Development Authority), Ireland, 08/09/2016)
      Nitrous oxide (N2O) is an important and potent greenhouse gas (GHG). Although application of nitrogen (N) fertiliser is a feature of many grazing systems, limited data is available on N2O emissions in grassland as a result of the interaction between urine, dung and fertiliser N. A small plot study was conducted to identify the individual and interactive effects of calcium ammonium nitrate (CAN) fertiliser, dung and urine. Application of CAN with dung and urine significantly increased the mass of N2O-N emission. Importantly, the sum of N2O-N emitted from dung and CAN applied individually approximated the emission from dung and CAN fertiliser applied together, that is, an additive effect. However, in the case of urine and CAN applied together, the emission was more than double the sum of the emission from urine and CAN fertiliser applied individually, that is, a multiplicative effect. Nitrous oxide emissions from dung, urine and fertiliser N are typically derived individually and these individual emission estimates are aggregated to produce estimates of N2O emission. The presented findings have important implications for how individual emission factors are aggregated; they suggest that the multiplicative effect of the addition of CAN fertiliser to urine patches needs to be taken into account to refine the estimation of N2O emissions from grazing grasslands.
    • Mapping Soils in Ireland

      Simo, Iolanda; Constanje, R.; Fealy, Reamonn; Hallett, S.; Hannam, Jacqueline; Holden, Nicholas M.; Jahns, G.; Jones, B.; Massey, P.; Mayr, T.; et al. (CRC Press, 2014)
      Harmonised soil data across Europe with a 1:250 000 geo-referenced soil database will allow for exchange of data across member states and the provide the information needed for reporting on issues re-lating to soil quality under a future Soil Framework Directive. The current status of soils data available in Eu-rope is inconsistent at best. The Irish Soil Information System (ISIS) project is currently developing a national soil map of 1:250,000 and an associated digital soil information system, providing both spatial and quantita-tive information on soil types and properties across Ireland. Both the map and the information system will be freely available to the public through a designated website.
    • Modelling phosphorus loss from agricultural catchments : a comparison of the performance of SWAT, HSPF and SHETRAN for the Clarianna catchment

      Nasr, Ahmed Elssidig; Bruen, Michael; Parkin, Geoff; Birkinshaw, Steve; Moles, Richard; Byrne, Paul; Environmental Protection Agency (IWA Publishing, 02/07/2012)
      Much research in Europe at present has been directed at generating and assessing modelling tools for use in catchment management, driven by the requirements and schedule of the Water Framework Directive. A logical first step is to assess the suitability of existing models for this task so that any resources used in generating new models can be targeted at actual modelling needs. Crucial questions, relating to the model structure and complexity and spatial and temporal scales required must also be addressed. This paper reports a comparison of the performance and suitability of three "off-the-shelf" distributed catchment models, each with a different level of complexity, applied to modelling phosphorous losses from the Clarianna catchment in Ireland. In this paper, the performance of three such models (SWAT, HSPF and SHETRAN/GOPC) is compared, both in estimating discharges and phosphorous loads in the Clarianna catchment. The flow comparison has showed that the HSPF model was the best in simulating the mean daily discharges. However, the best calibration results for daily total phosphorus loads in the study catchment has been achieved by the SWAT model.
    • Modelling soil bulk density at the landscape scale and its contributions to C stock uncertainty

      Taalab, K.P.; Corstanje, R.; Creamer, Rachel E.; Whelan, M. J.; Environmental Protection Agency (European Geosciences Union, 12/07/2013)
      Soil bulk density (Db) is a major contributor to uncertainties in landscape-scale carbon and nutrient stock estimation. However, it is time consuming to measure and is, therefore, frequently predicted using surrogate variables, such as soil texture. Using this approach is of limited value for estimating landscape-scale inventories, as its accuracy beyond the sampling point at which texture is measured becomes highly uncertain. In this paper, we explore the ability of soil landscape models to predict soil Db using a suite of landscape attributes and derivatives for both topsoil and subsoil. The models were constructed using random forests and artificial neural networks. Using these statistical methods, we have produced a spatially distributed prediction of Db on a 100 m × 100 m grid, which was shown to significantly improve topsoil carbon stock estimation. In comparison to using mean values from point measurements, stratified by soil class, we found that the gridded method predicted Db more accurately, especially for higher and lower values within the range. Within our study area of the Midlands, UK, we found that the gridded prediction of Db produced a stock inventory of over 1 million tonnes of carbon greater than the stratified mean method. Furthermore, the 95% confidence interval associated with total C stock prediction was almost halved by using the gridded method. The gridded approach was particularly useful in improving organic carbon (OC) stock estimation for fine-scale landscape units at which many landscape–atmosphere interaction models operate.
    • Nitrous Oxide Emissions

      Hyde, Bernard; Ryan, Mary; Hawkins, M.; Connolly, John; Carton, Owen T.; Environmental Protection Agency (Teagasc, 01/04/2005)
      Nitrous oxide (N2O) is one of the three most important greenhouse gases (GHG). Nitrous oxide emissions currently account for approximately one third of GHG emissions from agriculture in Ireland. Emissions of N2O arise naturally from soil sources and from the application of nitrogen (N) in the form of N fertilizers and N in dung and urine deposition by grazing animals at pasture. Nitrous oxide emission measurements were conducted at three different scales. Firstly, a large-scale field experiment was undertaken to compare emission rates from a pasture receiving three different rates of N fertilizer application and to identify the effects of controlling variables over a two-year period. Variation in emission rates was large both within and between years. Two contrasting climatic years were identified. The cooler and wetter conditions in year 1 gave rise to considerably lower emission levels than the warmer and drier year 2. However, in both years, peak emissions were associated with fertilizer N applications coincident with rainfall events in the summer months. A small-plot study was conducted to identify the individual and combined effects of fertilizer, dung and urine applications to grassland. Treatment effects were however, difficult to obtain due to the overriding effects of environmental variables. Thirdly, through the use of a small-scale mini-lysimeter study, the diurnal nature of N2O emission rates was identified for two distinct periods during the year. The occurrence of a diurnal pattern has important implications for the identification of a measurement period during the day which is representative of the true daily flux. The research presented aims to identify the nature and magnitude of N2O emissions and the factors which affect emission rates from a grassland in Ireland. Further work is required to integrate the effects of different soil types and contrasting climatic regimes across soil types on N2O emissions.
    • Pathways for Nutrient Loss to Water; Slurry and Fertilizer Spreading

      Ryan, T. Declan; Holden, Nicholas M.; Carton, Owen T.; Fitzgerald, D.; Murphy, F.; Environmental Protection Agency (Teagasc, 08/07/2008)
      There are almost 150,000 farms in Ireland and these contribute substantial quantities of N and P to inland and coastal waters. Some of these nutrients are carried from wet soils by overland flow and by leaching from dry soils. Farm practice can reduce the loss from farms by judicious management of nutrients. Improvements are required to diminish export of nutrients without impairing operations on the farm. Literature regarding nutrient loss from agriculture was reviewed in this project and maps were prepared to predict best slurry spreading times around Ireland. Two further maps were prepared to show slurry storage requirement on farms.
    • Pedotransfer functions for Irish soils – estimation of bulk density (ρb) per horizon type

      Reidy, Brian; Simo, Iolanda; Sills, P.; Creamer, Rachel E.; Environmental Protection Agency (European Geosciences Union, 18/01/2016)
      Soil bulk density is a key property in defining soil characteristics. It describes the packing structure of the soil and is also essential for the measurement of soil carbon stock and nutrient assessment. In many older surveys this property was neglected and in many modern surveys this property is omitted due to cost both in laboratory and labour and in cases where the core method cannot be applied. To overcome these oversights pedotransfer functions are applied using other known soil properties to estimate bulk density. Pedotransfer functions have been derived from large international data sets across many studies, with their own inherent biases, many ignoring horizonation and depth variances. Initially pedotransfer functions from the literature were used to predict different horizon type bulk densities using local known bulk density data sets. Then the best performing of the pedotransfer functions were selected to recalibrate and then were validated again using the known data. The predicted co-efficient of determination was 0.5 or greater in 12 of the 17 horizon types studied. These new equations allowed gap filling where bulk density data were missing in part or whole soil profiles. This then allowed the development of an indicative soil bulk density map for Ireland at 0–30 and 30–50 cm horizon depths. In general the horizons with the largest known data sets had the best predictions, using the recalibrated and validated pedotransfer functions.
    • Real-time forecasting of pesticide concentrations in soil

      McGrath, Gavan; Rao, P. Suresh C.; Mellander, Per-Erik; Kennedy, Ivan; Rose, Michael; van Zwieten, Lukas; Grains Research and Development Corporation grant; Lee A. Reith Endowment in the Lyles School of Civil Engineering at Purdue University; Environmental Protection Agency; DAN00180; et al. (Elsevier, 2019-01-31)
      Forecasting pesticide residues in soils in real time is essential for agronomic purposes, to manage phytotoxic effects, and in catchments to manage surface and ground water quality. This has not been possible in the past due to both modelling and measurement constraints. Here, the analytical transient probability distribution (pdf) of pesticide concentrations is derived. The pdf results from the random ways in which rain events occur after pesticide application. First-order degradation kinetics and linear equilibrium sorption are assumed. The analytical pdfs allow understanding of the relative contributions that climate (mean storm depth and mean rainfall event frequency) and chemical (sorption and degradation) properties have on the variability of soil concentrations into the future. We demonstrated the two uncertain reaction parameters can be constrained using Bayesian methods. An approach to a Bayesian informed forecast is then presented. With the use of new rapid tests capable of providing quantitative measurements of soil concentrations in the field, real-time forecasting of future pesticide concentrations now looks possible for the first time. Such an approach offers new means to manage crops, soils and water quality, and may be extended to other classes of pesticides for ecological risk assessment purposes.