So, how to minimize N losses to keep them below thresholds that degrade environmental quality? • Achieve high N fertilizer efficiency • Get most of the applied N taken up by the crop and either removed in harvested materials (grain, stover, straw) or transformed into soil organic matter (SOM) through decomposition of returned crop residues • Highest N fertilizer efficiency is achieved when N supply from all sources (residual nitrate, mineralization of SOM, and applied fertilizer) is congruent with crop N demand in terms of quantity, timing, and spatial variability • Tools: split applications, slow‐release, inhibitors, site‐specific or zone‐specific variable‐rate, canopy sensors, simulation models • Avoid erosion
But what is N fertilizer efficiency, and how to measure it?
It’s complicated‐‐‐Manifestations of nitrogen use efficiency 60 Agronomic efficiency (dY/dF, kg kg -1 ) (a) Yield Grain yield (Y, 1000 kg ha -1 ) 50 dY/dF 40 500 Ratio Y/F (kg/kg) 400 PFP 300 30 200 100 20 0 0 50 100 150 200 10 dY/dF 0 0 50 100 150 200 Fertilizer N (F, kg ha -1 )
Metrics of nitrogen fertilizer use efficiency Partial factor productivity from applied nitrogen PFP N = kg grain produced per kg of applied N Agronomic efficiency (AE) of applied N AE N = kg grain yield increase per kg applied N Recovery efficiency (RE) of applied N AE N = PE N x RE N RE N = kg N taken up from fertilizer per kg N applied Requires N fertilizer Physiological efficiency (PE) of applied N omission plot to PE N = kg grain yield increase kg ‐1 fertilizer N taken up estimate these parameters
Nitrogen fertilizer omission plots: Yield and N uptake from omission plots are compared to N uptake and yield with applied N to estimate N fertilizer efficiency
Example for corn: Partial Factor Productivity (PFP), Agronomic efficiency (AE), Nitrogen Fertilizer Uptake Efficiency Yield without applied N = 80 bu/ac Yield with 180 lb N/ac = 200 bu/ac Yield increase from N = 120 bu/ac (6720 lb/ac) PFP = (200 bu/ac)/(180 lb N/ac) = 1.11 bu/lb N AE = (120 bu/ac)/(180 lb N/ac) = 0.67 bu/lb N Nitrogen uptake efficiency = N uptake from fertilizer/N applied Nitrogen uptake efficiency = 124 lb N/ac uptake/180 lb N applied = 0.69 lb N uptake per lb of applied N (assumes grain contains 1.25%N, stover 0.6%N, and harvest index = 50%)
Nitrogen fertilizer omission plots: Yield and N uptake from omission plots are compared to N uptake and yield with applied N to estimate N fertilizer efficiency But establishing N fertilizer omission plots within large production fields is logistically difficult and time consuming!
FALL, 2017 ISSUE
Current methods to track progress towards environmental goals in absence of direct measures of N efficiency and N losses: Counting practices (performance too variable across soils, climates, tillage method, etc….) Direct monitoring (too expensive) Complex models (not adequately validated)
We need a better way to measure environmental progress: an environmental performance indicator Characteristics of a suitable indicator: • Simple (easily collected field‐level data) • Robust (directly related to environmental outcomes) • Meaningful to producers (related to other aspects of sustainability) • Scalable (from field to watershed to region)
Nitrogen balance approach: applying sufficient N to optimize profit while minimizing the nitrogen surplus and maintaining soil organic matter levels N deficit : when harvested grain removes more N than applied in fertilizer and manure N surplus : when harvested grain removes less than N applied in fertilizer and manure
Nitrogen Balance N inputs to the field: N outputs from the field: Fertilizer, N2 fixation, manure, Harvested materials, soil erosion, compost, deposition, irrigation water nitrate, nitrous oxide, ammonia Synchronous N Crop and soil supply and management demand, cover practices that crops, crop influence yield rotation with and N uptake legumes, affect the N N balance = N inputs – N outputs tillage balance (the surplus is at risk of loss) method, etc….
What makes N balance such a good indicator? • N balance is a direct measure of N fertilizer pollution • It responds to farm management, and offers flexibility to farmers to use a wide variety of practices; • It can be used to quantify environmental outcomes (N 2 O emissions and nitrate leaching); • It relates to other sustainability metrics. • It requires very little field‐ and farm‐level data!
N balance is a direct measure of sustainable intensification N balance is a measure of yield‐ From: McLellan et al. 2018 scaled N losses: • Reducing yield reduces food production and requires more land in crop production • Higher yields increase food production and requires less land for food production • Focusing on N balance avoids the problems associated with Sustainable intensification – producing tradeoffs when focusing on N more food using fewer resources and/or fertilizer efficiency alone producing less environmental damage
Is there evidence showing the N balance approach works? Relationship between nitrate in surface waterways in Denmark before and after using an N balance approach to benchmark N management performance, Henson et al., 2017.
Most farmers are good environmental stewards But it’s hard to convince non‐farm population and those concerned about the environment
Window of Opportunity? Agriculture has a window of opportunity to be proactive about addressing N pollution in ways that work for farmers A nitrogen management framework based on a sound indicator of N losses can help farmers: • demonstrate to policymakers and others that they are reducing N pollution; and • improve the overall sustainability of their operations
Power of farmer‐reported ag databases 1. To achieve higher profits and accelerate yield growth rates 2. Substantially reduce the negative environmental footprint of agriculture • Nutrient losses to ground and surface waters • Global warming intensity • Loss of wildlife habitat and biodiversity 3. Ensure safe, nutritious, affordable, accessible food supply
What would a global farmer‐reported database look like? • Public–sector data (high quality, high spatial resolution) • Long‐term (20+ years) and current weather data (daily) • Soil properties that govern crop growth and environmental performance • Water resources (stream flows, groundwater and reservoir storage levels) • Farmer‐reported, geo‐referenced, farmer‐owned and controlled database on field management • Crop rotation, tillage method, current season crop, yield, crop variety and maturity rating, sowing date, plant population, nitrogen rate/form/timing of application, phosphorus rate, pesticide use • Private sector adds value through development of products such as decision‐support tools, forecasts, and improved seed and other input products for pest management, irrigation, soil quality, etc.
Benchmarking N balance for Improved Nitrogen Management
Summary • N balance offers a new way of measuring progress in reducing fertilizer pollution that is scientifically‐robust, reflects field management, uses a small set of easily‐ collected field‐level data, and aligns improved environmental outcomes with improved productivity (and economic) outcomes • N balance data from the field level can be upscaled to track performance at watershed to regional and national levels using innovative spatial statistics, or through the food supply chain to document corporate progress towards sustainability commitments • The agricultural community can use N balance to show that the industry is proactive in using improved crop and soil management practices to reduce N losses and improve environmental performance
Summary • N balance offers a new way of measuring progress in reducing fertilizer pollution that is scientifically‐robust, reflects field management, uses a small set of easily‐ collected field‐level data, and aligns improved environmental outcomes with improved productivity (and economic) outcomes • N balance data from the field level can be upscaled to track performance at watershed to regional and national levels using innovative spatial statistics, or through the food supply chain to document corporate progress towards sustainability commitments • The agricultural community can use N balance to show that the industry is proactive in using improved crop and soil management practices to reduce N losses and improve environmental performance
Summary • N balance offers a new way of measuring progress in reducing fertilizer pollution that is scientifically‐robust, reflects field management, uses a small set of easily‐ collected field‐level data, and aligns improved environmental outcomes with improved productivity (and economic) outcomes • N balance data from the field level can be upscaled to track performance at watershed to regional and national levels using innovative spatial statistics, or through the food supply chain to document corporate progress towards sustainability commitments • The agricultural community can use N balance to show that the industry is proactive in using improved crop and soil management practices to reduce N losses and improve environmental performance
FOCUSING ON M.O.M. BY TRACKING THE P.A.N. Howard Brown Illini FS June 27, 2018
“We lost all the applied N due to the heavy rains this Spring.” Crop Consultant April, 2009
Approach • N applied within 7 days of 2 week rainy period + form (significant) • Still in NH 4 • Representative sample challenge • Sampled 3 farms (1 site each)
Location of the Spring‐Applied AA Plant‐Available N (ppm) Smith Farms (0‐1 ft. Depth) 120 100 Nitrate‐N 80 Ammonium‐N 60 40 20 0 0 3 6 9 12 15 18 21 24 27 30 Sample Position (Inches) ppm NO 3 ‐N: 27.7 ppm NH 4 ‐N: 8.3 Plant‐Available N: 36.0 ppm
Recommendation: • Suggested no supplemental N needed • Applied strips of supplemental N • No response to strips at harvest time
“If we can quantify PAN at a point‐in‐time why not track it over time.”
NUTRIENT NUTRIENT LOSS UTILIZATION REDUCTION STRATEGY STRATEGY “… to steer outreach and education efforts to help farmers address nutrient loss.”
PURPOSE PURPOSE • Inventory • Inventory • Track • Track • Verify • Verify TM • Apply • Apply N Management System New N Management Tool
Provides a window into the soil profile to learn more about the behavior of P lant‐ A vailable N (PAN).
30” 10 Cores 0‐1 ft. 10 Cores 0‐1 ft. Same hole: 10 Cores 1‐2 ft. Same hole: 10 Cores 1‐2 ft.
Notch For 12”
Mark for the 24” Depth
2018 Tracking www.n‐tracker.com www.n‐tracker.com Register a Site Log‐in/Register
Following Registration • Sampled within 3 business days • Report generated within 6 business days • Report posted at www.n‐tracker.com • Currently focused on salesperson report delivery • Testing direct farmer access
DATA SUMMARY SOIL NITROGEN LAB RESULTS (Estimate) 0 ‐ 1 ft. Sampling 1 ‐ 2 ft. Sampling Depth Depth 0 ‐ 2 FT. SAMPLING DEPTH TOTAL Date NO3‐N NH4‐N NO 3 ‐N NH 4 ‐N NO3‐N NH4‐N PAN % NH4 Total N Applied Tested (ppm) (ppm) (ppm) (ppm) (Lbs/A) (Lbs/A) (lbs/A) PAN (Lbs/A) 11/20/17 7 3 8 2 60.0 20.0 80.0 25.0% 0 4/16/18 11 28 10 7 84.0 140.0 224.0 62.5% 120 05/25/18 28 9 13 5 164.0 56.0 220.0 25.5% 120
PRODUCER INFORMATION Site ID: NTS‐15129292929 Prev. Crop: Soybean Registered By: Howard Brown # of N Appl: 2 Producer Name: John Smith Target N Rate: 200 Field Name: South of Home Target Yield: 230 NITROGEN APPLICATION HISTORY Date N Rate Applied Applied N Source Placement (Lbs/A) Stabilizer Used 03/23/18 Anhy. Am. Injected 120 N‐Serve Total Lbs. Applied: 200
PLANT‐AVAILABLE N SOIL UPDATE: Projected Pounds of N/Acre Needed by Crop 275Lbs. Pounds of PAN Detected at 0‐2 feet: 220Lbs. N/Acre Remaining to Meet N Requirement: 55 Lbs. REVIEWER: COMMENTS: Allowing for 45 lbs. of N to be released from soil O.M. (50% of estimated potential release), there may be a need for an additional 10 lbs. N to meet the 2018 corn crop's N requirement at this site.
Disclaimer: … Interpretation of any data in this report is an estimate at the point of sampling. It is up to the participant to determine whether the findings at the point of represent a larger part of the field.
Kankakee Bloomington Danville Champaign Charleston 305 Sites in 2018 305 Sites in 2018
PLANT‐AVAILABLE N vs. WEEKLY RAINFALL and N APPLIED (Accumulated) 300 8 N Applied (Lbs N/A) Nitrate‐N (lbs/A) Lbs. Plant‐Available N/Acre (Upper 2 Ft.) Ammonium‐N (lbs/A) Weekly Rainfall 250 6 Tracking applied N 200 Rainfall (inches) 150 4 Nitrification Weekly Rainfall 100 2 Residual N 50 0 0
NO3‐N NH4‐N NO3‐N NH4‐N 244 250 250 232 HIGH GROUND LOW GROUND 40 Field 1 Field 1 52 Plant‐Available N (Lbs. N/A Upper 2 ft.) Plant‐Available N (Lbs./A Upper 2 ft.) 200 200 204 180 150 150 24 28 16 100 100 24 104 100 100 80 50 50 0 0 0‐1 ft. 1‐2 ft 0‐2 ft. 0‐1 ft. 1‐2 ft 0‐2 ft.
NO3‐N NH4‐N 300 300 288 300 LOW GROUND PONDED GROUND 276 HIGH GROUND Field 3 Field 3 100 Field 3 92 250 250 250 Plant‐Available N (Lbs./A Upper 2 ft.) 204 200 200 200 60 188 184 64 68 150 150 150 144 36 32 112 100 100 100 104 28 24 84 80 72 64 50 50 50 0 0 0 0‐1 ft. 1‐2 ft 0‐2 ft. 0‐1 ft. 1‐2 ft 0‐2 ft. 0‐1 ft. 1‐2 ft 0‐2 ft.
Plant‐Available N (Lbs. N/A) in Upper 2 Ft. at V6 1 2 250 Plant‐Available N (Lbs. N/Acre ‐ 2 ft.) 224 Original Site 204 188196 200 168 172 164160 152 150 124 100 4 100 3 50 5 9 0 Original 1 2 3 4 5 6 7 8 9 Average Sampling Site Location 7 8 6
350 Estimated PAN Lbs./Acre (0‐2 Ft.) 284 PAN 0‐2 Ft. 300 224 Applied N Rate 200 250 164 200 148 150 Normal 100 50 Response 0 6/2/17 6/8/17 6/16/17 6/23/17 7/14/17 344 PAN 0‐2 Ft. 350 296 Applied 256 Estimated PAN Lbs./Acre (0‐2 Ft.) 300 236 216 250 200 Abnormal 150 Response? 100 50 0 6/2/17 6/8/17 6/16/17 6/23/17 7/14/17
OUTREACH www.nu‐tracker.com 2018 PROJECT: 5 High Schools
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