Slide 1

Clain Jones, Andrew John, Adam Sigler, Perry Miller and Stephanie Ewing Department of Land Resources and Environmental Sciences Effect of Agricultural Practices on Nitrate Leaching in the Judith River Watershed Slide 2 Project Sub-Objectives Evaluate the effects of alternative agricultural management practices on: 1.Nitrate Leaching 2.Net Revenue Slide 3 Nitrate leaching in Montana agroecosystems: Concept and timing Highest precipitation period: Late Apr to Mid-June Highest nitrate levels in soil: after fallow and after fertilization (often Apr in Judith Basin) How do those periods compare with crop N uptake? Fallow Slide 4 Top-dress amount and timing based on wheat growth stage to not hurt yield Nutrient Uptake Timing (EB0191) http://landresources.montana.edu/soilfertility/publications.html Saskatchewan Adapted from Malhi et al. 2006 Apr May June JulyAug Slide 5 Deep Soil Water Collected Slide 6 Practices that can decrease nitrate leaching in agro-ecosystems Seed perennial and/or deep rooted annual crops Sprinkle vs flood irrigation Soil sample for nitrate to determine N fertilizer rate Select reasonable yield goal Credit N from manure and legumes Fertilize in spring rather than fall Use a slow release fertilizer Split application Grow legumes (dont need to fertilize with N) Recrop (crop every year) rather than summer fallow Slide 7 Study Design: Management Practices Grower Standard Practice (GSP) Wheat-barley-fallow rotation Nitrogen fertilizer: surface broadcast, early spring Alternative Management Practices (AMP) vs GSP Pea vs Fallow Split fertilizer application vs single early spring broadcast Controlled release urea (CRU) with seed vs early spring broadcast Alternative management practices were selected by our two research advisory groups based on how adoptable the practices were Slide 8 Study Design: Fields Comparisons of AMP vs GSP treatments were made for two years (2013, 2014) on two fields each. Fields located near Stanford (Field A), Moccasin (Field B), and Moore (Field C) Field A Slide 9 Field B Study Design: Field Layout and Sampling Locations 2014 Winter Wheat GSP AMP Slide 10 2012 2013 2014 CRUGSPSplit App Fallow CRUGSPSplit App Study Design: Field C (near Moore) Slide 11 Calculating Leaching by Nitrogen Mass Balance Leached Nitrate = Inputs outputs + initial soil nitrate final soil nitrate Slide 12 Nitrogen Mass Balance Leached Nitrate = Fertilizer N + N fixed + Net N mineralized denitrification crop N uptake N volatilized + initial soil nitrate final soil nitrate Fertilizer N: from Judith collaborators N-fixed: natural abundance method Net N mineralized denitrification: soil nitrate differences when no leaching based on precipitation and soil moisture (e.g. 2012 to mid-May 2013). Modelled during other periods. Crop N uptake biomass sampling N volatilized Rick Engels results from Fergus County Slide 13 Status of leaching estimate Still developing mineralization model Can calculate available N recovery for 2013 winter wheat. Available N Recovery (%) = ((N in grain and straw)/(soil nitrate in Aug 2012 + fertilizer N))*100 Differences between treatments could suggest differences in leaching Slide 14 Available Nitrogen Recovery in 2013 winter wheat * - Significant difference (P