Nutrient Use Efficiency: A Midwest Perspective T. Scott Murrell U.S. Northcentral Director Nutrient Efficiency & Management Conference, Rochester MN. 15 Feb. 2011
Outline The concept of nutrient use efficiency Three measures of nutrient use efficiency: Partial factor productivity Agronomic efficiency Partial nutrient balance Spatial scale National/state/watershed (university/agency scientists) Farm/field/within-field (farmers, agency personnel, and consultants/advisers)
Thoughts about nutrient use efficiency More is better Nutrient use efficiency Improves environment Saves money
Nutrient use efficiency: The role of science Role of science Nutrient use efficiency Figure out how to measure it Figure out how it relates to the many objectives we have for our feed/fiber/food/fuel supplies (quality, quantity, sustainability, profitability, etc.) What is too little? What is enough? What is too much?
Making nutrient use efficiency something we can measure: Grain crop example Nutrient use efficiency Things we can measure Grain yield of a fertilized crop Grain yield of an unfertilized crop Fertilizer application rate Nutrient content of the grain
Making nutrient use efficiency something we can measure: Grain crop example yield fertilizer rate Nutrient use efficiency Things we can measure Grain yield of a fertilized crop Grain yield of an unfertilized crop Fertilizer application rate Nutrient content of the grain
Nutrient use efficiency as measured by: Partial factor productivity yield fertilizer rate Measurement: Spatial Scales National/state/county/watershed scale: Crop production statistics Fertilizer use statistics Farm/field/within-field scale: Crop yield records/maps Fertilizer application records/maps
Partial factor productivity (bu/lb N) Partial factor productivity of nitrogen for corn grain: Scale: U.S., 1964-2008 1.40 1.20 1.00 0.80 0.60 0.40 0.20 0.00 1960 1970 1980 1990 2000 2010 Data: USDA-NASS, USDA-ERS Year
Ratio of Bushels Produced per Lb N Fertilizer Input Partial factor productivity of nitrogen for corn grain: Scale: Minnesota state, 1992-2010 1.5 1.3 1.0 0.8 0.5 0.3 0.0 Statewide "NUE" on Corn Using the N Balance Method Data: MN Dept. Agric.
Partial factor productivity (bu/lb N) Partial factor productivity of nitrogen for corn grain: Scale: Field, north central Indiana 1.40 1.20 1.10 1.20 1.12 1.00 0.80 0.90 0.60 0.40 0.20 0.00 2005 2007 2008 2010 Year Data: Lance Murrell Consulting and IPNI
Partial Factor Productivity of nitrogen for corn grain: Scale: Within-field, north central Indiana Partial factor productivity (bu/lb N) < 0.42 0.42 0.68 0.68 0.94 0.94 1.20 1.20 1.46 1.46 1.72 > 1.72 Data: Lance Murrell Consulting and IPNI
Nutrient use efficiency as measured by: Partial factor productivity yield fertilizer rate Guidelines The trend over time has been toward increasing partial factor productivity, viewed as positive What should the target be?
Partial factor productivity of nitrogen (PFP N ) for U.S. corn vs. annual total nitrogen flux to the Gulf of Mexico R 2 = 0.36 p value = 0.002 0.54 0.63 0.71 0.80 0.89 0.98 1.07 1.16 1.25 1.34 US. Corn Partial Factor Productivity, bu/lb N Data: C.S. Snyder, IPNI
Making nutrient use efficiency something we can measure: Grain crop example yield increase fertilizer rate Nutrient use efficiency Things we can measure Grain yield of a fertilized crop Grain yield of an unfertilized crop Fertilizer application rate Nutrient content of the grain
Nutrient use efficiency as measured by: Agronomic efficiency yield increase fertilizer rate Guidelines There is a minimum agronomic efficiency that must be exceeded if the nutrient application is to be profitable in the season for which it is applied This minimum is equal to the ratio of the nutrient price to the crop price
Nutrient use efficiency as measured by: Agronomic efficiency yield increase fertilizer rate Example: Guidelines Nitrogen price = $0.45 Crop price = $4.50 Nitrogen:crop price ratio = 0.1 So agronomic efficiency must be more than 0.1 to be profitable
Nutrient use efficiency as measured by: Agronomic efficiency yield increase fertilizer rate Measurement: Spatial Scales National/state/county/watershed scale: Databases of fertilizer rate studies Crop production statistics Farm/field/within-field scales: Omission plots
Agronomic efficiency of nitrogen for corn grain Scale: State http://extension.agron.iastate.edu/soilfertility/nrate.aspx
Agronomic efficiency (bu increase/lb N) Estimated agronomic efficiency of nitrogen for corn grain: Scale: State, 2001-2010 averages Rotation: CC SC 0.60 0.50 0.51 0.46 0.48 0.48 0.40 0.30 0.37 0.40 0.35 0.32 0.20 0.10 Minimum to exceed 0.00 IA IN MI MN OH Data: USDA-NASS, IA State Univ. Corn Nitrogen Rate Calculator
Agronomic efficiency of nitrogen for corn grain: Scale: Field Reduced N rate (40 lb N = 113 bu/acre) Normal N rate (215 lb N = 200 bu/acre) Data: Lance Murrell Consulting and IPNI
Agronomic efficiency of nitrogen for corn grain: Scale: Field http://nanc.ipni.net/
Normal N rate Yield with normal N rate The 0 rate we want to find Reduced N rate Yield with reduced N rate
Yield response (bu/acre) Agronomic efficiency = 0.61 bu increase/lb N 131 bu/acre response with 215 lb N Minimum to exceed: 0.1 bu increase/lb N
Making nutrient use efficiency something we can measure: Grain crop example amount removed amount applied Nutrient use efficiency Things we can measure Grain yield of a fertilized crop Grain yield of an unfertilized crop Fertilizer application rate Nutrient content of the grain
The partial of partial nutrient balance Amount applied Amount removed Fertilizer application Manure application Nutrients in irrigation water Nitrogen fixation Atmospheric deposition Deposition from other landscape areas Crop harvest Leaching losses Runoff losses Erosion losses Gaseous losses
Nutrient use efficiency as measured by: Partial nutrient balance amount removed amount applied Guidelines Partial nutrient balance values: approx. 1.0 removal = application (some sense of sustainability) less than 1.0 removal is less than application (soil nutrient levels are increasing) greater than 1.0 removal is more than application (soil nutrient levels are decreasing)
Nutrient use efficiency as measured by: Partial nutrient balance amount removed amount applied Measurement: Spatial Scales National/state/county/watershed scale: Fertilizer use statistics Crop production statistics Nutrient removal estimates Farm/field/within-field scales: Fertilizer application rates Crop yield Nutrient concentration (from soil and plant analysis lab)
http://nugis.ipni.net/map/
Partial factor productivity Partial nutrient balance of phosphorus: Scale: Watershed, Cannon 1987-2007 http://nugis.ipni.net/map/ 1.40 1.20 1.00 0.80 0.60 0.40 0.20 0.00 1985 1990 1995 2000 2005 2010 Year
Partial nutrient balance Combining partial nutrient budgets with soil test information + Low soil test, and levels are expected to decline further High soil test, but levels are expected to decline 1.0 Low soil test, but levels are expected to increase High soil test, and levels are expected to increase further 0-0 Difference from target soil test level + (Actual soil test level target soil test level)
Partial nutrient balance of phosphorus: Scale: Within-field Agronomically sound partial nutrient budget Inappropriate partial nutrient budget
Summary Nutrient use efficiency is a general concept that must be translated into something measurable Partial factor productivity (bu/lb nutrient) U.S. is increasing, on average toward 1.2 to 1.3 Minnesota is increasing toward 1.4 Agronomic efficiency (bu increase/lb nutrient) Several states have 3 to 5 times the minimum efficiency needed to be profitable with nitrogen applications Partial nutrient balance (lb removed/lb applied) A balance of 1.0 is a guidepost Combining this information with soil tests provides agronomic interpretations
A Future Goal of Nutrient Use Efficiency Research
Environmental loss The Holy Grail of nutrient use efficiency? Acceptable level? Target efficiency Nutrient use efficiency