Nitrogen Management Tools for Reducing Nitrogen losses in the Chesapeake Bay Watershed John (Jack) Meisinger Soil Scientist, USDA-ARS, Beltsville, MD Adj. Assoc. Prof, Unv. Md, College Pk, MD
Principles for Managing Nitrogen (Meisinger & Delgado, 2002) Universal N Management Principles : Know the soil-crop-hydrologic cycle Apply proper rate of N - avoid excess N Apply N timed to crop demand Apply N with proper placement - incorporate Adaptive management mgt. w/ evaluation Cropping System Tools : Use rotations, add cover crop or forage crop Use: riparian buffers, CRP acres, wetlands
Basics of Adaptive Nutrient Management Develop Nut. Mgt. Plan Adjust Nut. Mgt. Plan Implement Nut. Mgt. Plan Evaluate Nut. Mgt. Plan
Nitrogen Cycle Leaks Denitrification losses: small-moderate 10-20% Ammonia losses: small-moderate 5-20% Crop Uptake: 50-60% Eroded organic & mineral N: small losses 1-5% Nitrate leaching Decades Days/wks Weeks/months Years Leaching losses: Large 10-40% Note: Major N Cycle Losses are Driven by Hydrology
Principles for Managing Nitrogen (Meisinger & Delgado, 2002) Universal N Management Principles : Apply proper rate of N - avoid excess N Use realistic yield estimates, e.g. yield history or yield monitor data for soil types within the field Include other N sources, e.g. manure analysis, manure spreader calibration, legume credits Use in-season monitoring tools, e.g. presidedress soil nitrate test (PSNT), LCM, Sensors
Connection Between Optimum N Management & the Environment (Adapted from Coale et al., 2000) Cont. Corn, no CC, 3-yr study, Mattepex silt loam, Lower eastern shore Grain Yield, bu/ac or Soil NO3-N lbs N/ac 200 180 160 140 120 100 80 60 40 20 0 4% Corn $4.00 / bu FN at $0.80 / lb 6% 0 50 100 150 200 250 300 Fert. N, lbs N/ac 23% 42% 650 600 550 500 450 400 350 300 250 Return to FN, $/ac Corn Grain Yield Fall Soil NO3 0-3 ft MRTN
Managing Nitrogen: Application Rate Yield & N Leached, UK Winter Wheat (K. Goulding, 2000) Yield, 100 kg / ha N Leached, kg N / ha 100 80 60 40 20 0 0 48 96 144 192 240 288 Fertilizer N Rate, kg N / ha
Principles for Managing Nitrogen (Meisinger & Delgado, 2002) Universal N Management Principles : Apply N timed to crop demand Apply N to avoid periods of potential loss, e.g. avoid the winter leaching season Use split N applications whenever possible, e.g. split N for winter wheat, sidedress N for corn
Timing Manure Applications (Sharpley & Lord, 1998) 30 Slurry or poultry manure Solid barnyard manure NO 3 -N leached, % of N added 20 10 0 Sept. Oct. Nov. Dec. Jan. Month applied
Planting vs Sidedress N for Corn Fox & Beegle, PA St. 200 180 Corn Grain Yield (bu/a) 160 140 120 100 80 60 40 20 0 Planting Sidedress At-Plant = 118 bu/a Sidedress = 127 bu/a
Principles for Managing Nitrogen (Meisinger & Delgado, 2002) Universal N Management Principles : Apply N with proper placement Incorporate manure and urea containing fertilizers, e.g. avoid surface applications with prolonged exposures to ammonia loss Use manure or UAN injection equipment that can maintain some residue cover
UAN Fertilizer Injector
Corn Grain Yield (bu/a) 140 120 100 80 60 40 20 Dribble vs Injected UAN (Fox & Beegle, PA St.) Avg. Benefit = 5 bu/ac Dribble Injected 0
Principles for Managing Nitrogen (Meisinger & Delgado, 2002) Universal N Management Principles : Cropping System Tools, cover crop Add a grass cover crop, rye or wheat, use good agronomic practices, e.g. good seed- soil contact, early planting, Use covers especially if high residual N, manured sites, drought sites, etc. Monitor establishment w/ remote sensing
N Leaching from Cover Crops, Beltsville Lysimeters, 2009-2010 (Meisinger & Ricigliano, 2010, Pers. Commun.) Cumulative kg NO3 N/ha Leached 120 100 80 60 40 20 no cover wht +N wht N rye N 0 0 50 100 150 200 Days After Planting (DAP)
Principles for Managing Nitrogen (Meisinger & Delgado, 2002) Universal N Management Principles : Ammonia Management Tools, tillage or injection Ammonia loss is rapid, 50-70% of NH4-N lost the first day from slurries Use immediate tillage or injection to reduce losses Conserve surface residues to manage erosion, e.g. use vertical tillage such as turbo-till or injection
Tillage Effects on NH 3 Loss Dairy Slurry, Wind Tunnels, 7d (Thompson & Meisinger, 2001, Meisinger unpub. 2009) 50 Surface % NH4-N Lost 40 30 20 10 0 Tillage Implement Ph'nx or Aer. Turbo Till 35% reduction Chisel Plow 80% reduction Inject or Disc 90% reduction Mold. Plow 99% reduction
Within-Season N Management Approaches Within-Season Approaches: Leaf Chlorophyll Meter (LCM), Pre-sidedress Soil NO 3 (PSNT), Ear Leaf N, Petiole NO 3 for Vegetables, End-of-Season Corn Stalk NO 3 (CSNT), Sensors Advantages: Can adjust for: prior crops, manure, irrigation, weather & soil interactions during the first part of the season Disadvantages: Future weather still uncertain, spatial variability remains Tests are labor intensive and slow, e.g. 1 PSNT person = 2,000 ac
MD Pre-sidedress Soil Nitrate Test (PSNT) (Meisinger et al., 1992)
MD Pre-sidedress Soil Nitrate Test (PSNT) (Meisinger et al., 1992) PSNT Good for ID ing N sufficient sites Very useful for manured sites, which are problematic > 21 ppm sufficient < 15 ppm deficient 15-21 ppm gray area
Adaptive N Management for PSNT: Adapt-N Information needed Soil/Tillage User ID / Field ID Latitude / Longitude Soil textural group Approximate field slope Drainage Soil test information Tillage information Organic Inputs Fertilizer/Crop Starter fertilizer type/rate/application date Additional fertilizer Cultivar maturity class Planting date Expected harvest population Manure applications: Two previous years / current year Previous sod crop 1st year corn after soybean? H. van Es, Cornell Univ.
Observations Adapt-N Input: High Resolution Precipitation Data Error-Corrected Radar Estimates Northeast Region Climate Center Observed 4X4 km H. van Es, Cornell Univ.
Adapt-N Input: High Resolution Temperature Data Elevation-Corrected Spatial Interpolations Northeast Region Climate Center Observed 4X4 km H. van Es, Cornell Univ.
Corn Stalk Nitrate Test (CSNT) Late Season Stalk Nitrate Test An autopsy of N management Procedure: Sample between ¼ milkline and 3 weeks after black layer 8 piece of stalk 6 above the ground Cut into pieces, dry, and send to the lab Opt. 700-2,000 ppm NO 3 -N
Late Season Stalk Nitrate Test Test Level Interpretation Management <700 ppm NO 3 -N Low N likely limited yield 700-2000 ppm NO 3 -N Optimal N adequate for high yield, but not excessive >2000 ppm NO 3 -N Excessive N was in excess of that needed for high yield
Pennsylvania Stalk Nitrate Summary 2000-05 from 1,692 obs. (D. Beegle PA St.) Stalk NO3 N (mg/kg) 20000 18000 16000 14000 12000 10000 8000 6000 4000 2000 0 Optimum
Real-Time Sensor with Sprayer Red NIR NDVI Reflectance in Red and NIR, Outputs data as NDVI & Ratio 60 cm 8 rates 60 cm NTech Industries, Inc. Oklahoma State Univ.
Real-Time Sensor with Sprayer GDVI N Applied
Field Strip Tests: A Valuable Approach The Original Strip Test The Broadbalk Experiment, Rothamsted UK, 1853
Principles for Managing Nitrogen (Meisinger & Delgado, 2002) Universal N Management Principles : Conduct Field Evaluations, Replicated Strip Tests Used for >150yrs, standard practice vs. alternative practices, keep it simple, but replicate Ex. Strip Tests: current N rate, +25% current N rate, -25% of current rate, and no-n strip Site data: soil types, rainfall, temperature, previous manure or legume, etc. Measure: yield w/ yield monitor, crop N status with leaf chloro. meter, PSNT, CSNT, etc.
Another Important in-field Corn Test N rates of 0 or 200 lb/ac along a transect Note: Grain Yield (kg/ha) 13500 11500 9500 7500 5500 3500 N=0 N=200 Elevation 315 314 313 312 311 Elevation (m) 1. Check ylds. lowest, & N response highest, on eroded side slope 2. High check ylds. and high soil N supply, at footslopes and areas with concave curvature. 3. For most of the field, opt. N rate between 80 and 120 lbs N/ac. 0 200 400 600 800 1000 Distance Along West Transect (ft) Kasper et al., 2003
Basics of Adaptive Nutrient Management Develop Nut. Mgt. Plan Adjust Nut. Mgt. Plan Implement Nut. Mgt. Plan Evaluate Nut. Mgt. Plan PSNT, CSNT, Yield Monitors, Sensors, Strip Tests, etc.
Real World N Management Is Tough! N is very complex The N cycle is leaky Dependent on weather We understand N behavior, but it is very difficult to predict Fertilizer NH 3 Volatilization High ph NH 4 + Animal Waste Microbes Mineralization Nitrification Immobilization NO 3 - N 2 Biological Fixation Crop Residues Organic Matter Crop Removal Crop Uptake N 2, N 2 O, NO Denitrification Predictions are difficult, especially about the future Yogi Berra Leaching
Short-term and Long-term Needs Short-term Implementation needs: Expand cover crop acreage, target high residual N sites Expand manure storage for dairies, to 12 month storage Expand manure injection in the Bay watershed Long-term Implementation needs: Develop private professional consultant program to implement adaptive nutrient management Develop N rate strip test program to optimize N rates for management zones within fields Research and develop algorithms for interpreting adaptive management tests (e.g. PSNT, etc)