# Managing Reactive N in

**the Environment C.S. Sny**  **der, PhD, CCA**  **Nitrogen Program Director** 

**Presented to**  **EPA FRRCC 2009 Food**  **riots in Haiti over high prices for**

**rice, beans and other food staples led to the ouster of the government on Saturday**  **.**

# IPNI is committed to a healthy **and adequate global food supply**

# EPA SAB Integrated **Nitrogen Committee**  **Report on Reactive**  **N (** 

# N **r )** 

**November 15, 2008**
• **Improved practices** - impact lowered through better management practices
• **Product substitution** - a product is developed or promoted which has a lower dependency on, or releases less, reactive nitrogen)
• **Transformation** - one form of N converted to another form
• **Source limitation** - introduction of Nr in environment lowered through preventive measures (e.g. **precision fertilizer application,**  **controls on NOx generation)** 
• **Removal** - in which Nr is sequestered from impacting a particular resource • **Improved use or reuse efficiency**  - efficiency of production that is dependent on Nr is improved (e.g. increased grain yields for lower Nr applied), or Nr wasted from one source is reused in another (e.g. algal farming). From DRAFT report Nov . 15, 2008

# EPA INC Draft Recommends **- Reduce**  **N r**  **Loss to Environment by**  **2 5%** 

• **Decrease livestock**  **- derived**  **ammonia emissions to approximately**  **8 0%**  **o f 1990** 
• **Decrease excess flows of Nr into streams,**  **rivers, and coastal sy stems**  **by a**  **pprox. 20%** 
• **Increase crop output while reducing**  **total Nr up to 20%**  **of applied artificial Nr.**
• **High priority f**  **or a targeted construction grants program**  **under the CWA (i.e wetlands)**  From DRAFT report Nov . 15, 2008**Galloway & Cowling, 2002; UNEP , 2003** 

# The Nitrogen Cycle Atmospheric nitrogen Atmospheric fixation and deposition

Animal manures and biosolids Industrial fixation (commercial fertilizers) Crop harvest Vo latilization

Denitrification Runoff and erosion

Leaching Organic nitrogen Ammonium

(NH 4 ) Nitrate (NO 3 ) Plant residues Biological fixation by legume plants Plant uptake

Input to soil Component Loss from soil - +**EP A**  **Hypoxia SA B**  **report suggested 45%**  **less total N AN**  **D 45%**  **less total P discharge to the Gulf to reduce** 

**hypoxia Notable**  **Declines** 

# Has nutrient discharge increased ?

# Discharge by 5 Major Sub **- basins**  Where is it coming from?

**16 61**  **84 74**  **64**

# USGS Estimates Loss of **N and P to Water Resources in Different Areas** 

SP ARROW - Modeled Estimate of N and P Discharge in W atersheds of the Mississippi R. Basin

**kg/ha .01**  **.01 -**  **0.1 0.1 to 1**  **1 to 5 5 to 10**  **>10 kg/ha**  **.001 .001**  **- 0.01**  **0.01 to 0.1**  **0.1 to 0.5 0.5**  **- 1.0**  **>1** Alexander et al. Environ. Sci. T echnol. 2008, 42, 822

– 830

# Sub **- basin**  **Contributions of N & P** 

### Vo **luntary actions**  **are reducing the “net” Nitrogen (N)**  **balance in the**  **Mississippi River**  **Basin; especially in tw**  **o key**  **upper sub**  **- basins.** 

### Vo **luntary actions are**  **also reducing the “net” phosphorus (P)**  **balance in the**  **Mississippi River**  **Basin; especially in**  **tw o**  **key upper sub**  **** **basins. This is a concern,**  **how ever**  **, because**  **soil P**  **may b**  **e “mined”, and may**  **l ead to y**  **ield reductions and lower**  **N use efficiency 60** 

**80 100**  **120 140**  **160 180**  **200**

**0 20**  **40 60**  **80 100**  **120 140**  **160 180**  **200 N ra**  **te, lb/A**  **wi th**  **P wi**  **th out P**  

# Effect of N and P on Corn Yield

Schlegel, Dhuyvetter , and Havlin, 1996 J. Produc. Agric. 9:1 **30 year average**  **N rate at max yield: with P**  **= 167 lb/A**  **without P**

**= 161 P**  **incr eased**  **N use efficiency**  **instead of**  **gr eatly**  **incr easing**  **N fertilizer**

**demand 0** 

**50 100**  **150 200** 

**0 40**  **80 120**  **160 200**  

### N ra **te, lb/A** **S o** **i l** **N O** **3 -** **N i** **n u** **p p** **e r** **1 0** **f t** **, l** **b /** **A**
**wi th**  **P wi**  **th ou**  **t P** 

# P Reduces Residual Soil Nitrate and **Potential for Nitrate Leaching** 

**At optimum N rate**  **P re**  **duced r esidual**  **nitrate by 66%** 

Schlegel, Dhuyvetter , and Havlin, 1996 J. Produc. Agric. 9:1 **30 year average** **0. 75**  **0. 66**  **0. 47**  **0. 33**  **0 0.**  **2 0.**  **4 0.**  **6 0.**  **8**

**0- 0-0-0**  **300-0-0-0 300-100-0-0**  **300-100-80-0 300-100-80-40**  **N- P-K-S,**  **k g/ha** **A p** **p a** **r e** **n t** **N r** **e c** **o v** **e r** **y e** **f f** **i c** **i e** **n c** **y Ar**  **row s**  **are % i**  **ncrease in apparent N relativ**  **e efficiency** 

**o ve**  **r prev**  **ious treatment** 

Gordon. Better Crops. 2005 ( KS, Car sandy loam ) Assumes uptake 1.4 lb N/bu grain 2 - year average (2001 - 2002) **40 % 41 %**  **14 % ---**  

# Balanced Fertilization **Improves Crop N Recovery** 

## Percent of soil samples requiring **annual** 

# P **fertilization to avoid profit**  **loss in most major crops in 2005**

Fixen et al. 2006 Summary of 3.4 million soil samples for 2005 growing season

## Percent of soil samples requiring **annual** 

# K **fertilization to avoid profit**  **loss in most major crops in 2005**

Fixen et al. 2006 Summary of 3.4 million soil samples for 2005 growing season

## Decadal - Scale Changes of Nitrate in Ground Water of the United States, 1988 – 2004. (Rupert. 2008. J. Environ. Qual. 37:S - 240 – S - 248)



### • 67% of sites (16 out of 24) - had no significant change in NO 3 

### concentrations

– All but 1 of the 8 others had increases in NO 3 

### • “A subset of wells had data on ground water recharge date; nitrate concentrations increased in response to the increase of N fertilizer use since about 1950.”NO 3 - N loads To tal N loads **Rebich and Remchek, 2007** Scientific Investigations Report 2007 – 5090

“ **Notable increasing trends in nitrite plus nitrate and total nitrogen at selected study sites w**  **ere attributed to both point and nonpoint**  **sources.”**

# Kitchen **and Goulding**  **(2001)** in Nitrogen in the Environment: Sources, Problems and Management

• **“ nitrogen**  **use efficiency ...rarely**  **exceeds 70% ...**  **.... often ranges**  **from 30 -**  **60% ”** 
• **“conversion of N inputs**  **to products**  **for arable crops can**  **be 60 -**  **70% o**  **r even more”**

# We can improve Nutrient Use **Efficiency & Effectiveness by implementing**  **Fertilizer BMPs ..... right source @ right rate @right time** 

**& right placement**  **4R Stewardship**

# Improving **Fertilizer N Use**

**Efficiency (NUE)**

• **Proper rates and sources -**  **best placement and proper timing** 
• **Nitrification inhibitors**  - slow the conversion of NH 4 + 

### to NO 3 - 

### • **Urease inhibitors**  – slow conversion to NH 4 + 

### and reduce potential NH 3 

### volatilization
• **Slow r**  **elease N fertilizers** - release N over the growing season, matching availability and crop needs
• **Site -**  **specific applications**

– Variable rate, and possibly variable source

– In - season sensing and variable rate/place applicationhttp://www .ipni.net/ipniweb/portal.nsf/0/d58a3c2deca9d7378525731e006066d5/$FILE/Revised%20NUE%20update.pdf 

# How **Do You Define and Rate NUE? NUE T**  **erm Calculation**  **Reported Examples**  **PFP** - Partial factor productivity Y/F **40 to 80** units of cereal grain per unit of N **AE** - Agronomic Ef ficiency (Y

- Y 0 )/F **10 to 30** units of cereal grain per unit of N **PNB** - Partial nutrient balance (removal to use ratio) U H /F **0 to > 1.0**  - depends on native soil fertility and fertility maintenance objectives **<1** in nutrient deficient systems (fertility improvement) **>1** in nutrient surplus systems (under replacement) **Slightly less than 1 to 1**  (system sustainability) **RE** – Recovery ef ficiency of applied nutrient (U - U 0 )/F **0.1 to 0.3** - proportion of P input recovered first year **0.5 to 0.9** - proportion of P input recovered by crops in

long - term cropping systems **0.3 to 0.5** - N recovery in cereals - typical **0.5 to 0.8** - N recovery in cereals - best management F - amt. nutrient applied, Y - yield of harvested portion with applied nutrient, Y 0 - yield of harvested portion with no applied nutrient, U H – nutrient content of harvested portion of crop, U – total nutrient uptake in aboveground biomass with nutrient applied, U 0 – total nutrient uptake in aboveground biomass with no nutrient applied0. 5

0. 6 0. 7 0. 8 0. 9 1. 0 1. 1 1. 2 1. 3 1. 4

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005buperlbofN 

## Corn grain produced **in the U.S. per unit of fertilizer**  **N used, 1964 to 2005.**

**0.76 1.15** 

**51% increase in N efficiency 12% increase in N fertilizer use**  **Since 1975:** *

*Application ra te for 2004 estimated as avg of 2003 & 2005.

Data sources: USDA Ag Chem Use Survey & Annual Crop Production. No USDA

survey data for 2004, 2006, 2007, 2008**(EP A**  **draft U.S. GHG**  **inv entory**  **, 1990**  **- 2007)** 

# N **2** 

# O Emissions Trends: Ag Soil **Management and Total Ag Sector** (EPA draft U.S. GHG inventory, 1990 - 2007)

“ Annual N 2 O emissions from agricultural soils fluctuated between 1990 and 2007, although overall emissions were 1.2. percent lower in 2007 than in 1990.N 2 O emissions from this source have not shown any significant long - term trend , as they are highly sensitive to the amount of N applied to soils, which has not changed significantly over the time - period, and to weather patterns and crop type.”

## U.S. GHG Emissions & N **2** 

## O from

**the Ag Sector –**  **CO 2**  

## Equiv. (EPA draft U.S. GHG inventory, 1990 - 2007)

**5.5% 5.6%**  **5.3% 4.5%**  **4.7% 4.5%** 
Ag sector N 2 O as portion of total US. GHG emissions

## U.S. GHG Emissions & N **2** 

## O from **Ag Soil Management –**  **CO 2**  

## Equiv. (EPA draft U.S. GHG inventory, 1990 - 2007)

**3.6% 3.6%**  **3.6% 3.1%**  **3.2% 3.1%** 
Ag soil mgmt. N 2 O as portion of total US. GHG emissions**http://w ww**  **.fertilizer .org**  **http://w ww**  **.ipni.net/bettercrops New**  **I PNI Practical**  **Guide: Fertilizer**  **Nitrogen BMPs to Limit Losses**  **that Contribute**  **to Global Wa**  **rming**

# • **N source**  **, rate**  **, placement**  **, and timing**  **.... which may include** 

– **Urease inhibitors** 

– **Nitrification inhibitors** 

– **Slow -**  **release materials**

– **Controlled -**  **release materials** 

## • **In combination with appropriate,**  **site**   ** specific cropping** **sy stem**  **and conservation**  **practices**

– **(e.g. conservation tillage, cover crops,**  **vegetative buffers, managed drainage, we**  **tlands, bioreactors, etc.)**  

## • **Fertilizer N BMPs can help minimize the potential for residual NO**  **3** 

## - **N accumulation**  **& losses**

# Intensified **Fertilizer BMP**

**Education & Outreach** 

# New Tools, Technologies,

**Opportunities ??** 
• John Deere - hi - speed (10 mph) anhydrous ammonia applicator
• Agrotain & Lange - Stegmann - $20 million Urea and Stabilized Nitrogen Center in St. Louis, MO
• Corn hybrids with improved N uptake/redistribution characteristics ???

### www.ipni.net

Better Crops, Better Environment ... through Science



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