Optical Sensing for Nitrogen Management

Sulochana Dhital, PhD Student

Oklahoma State University

Stillwater, OK

Mt. Everest

NEPAL

N

S

19811983

19851987

19891991

19931995

19971999

20012003

20052007

20092011

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

US Consumption of Nutrients

Nitrogen (N) Phosphate (P2O5) Potash (K2O)years

Thou

sand

Ton

s

Ammonia Cost and Natural Gas Price

Source: NYMEX Henry Hub, Fertecon, PotashCorp (August, 2014)

Nitrogen Use Efficiency (NUE)

World Nitrogen Use Efficiency (NUE): ~33%

(Raun and Johnson, 1999)

Dead Zone, Northern Gulf of Mexico

For 2014 August 1, the area of Hypoxic zone is 13,080 sq.km (5,052 sq. miles) is below 5 year average.

Source: Nancy N. Rabalais http://water.epa.gov/type/watersheds/named/msbasin/images/hypoxia_size_2013_lg.jpg

Dead Zone, Northern Gulf of Mexico

Source: http://www.gulfhypoxia.net/overview/

Excess nitrogen flowing down the Mississippi each year is estimated to be worth $750,000,000 (Science, Malakoff, 1998)

Hypoxia Worldwide Problem

Source: http://www.gulfhypoxia.net/overview/

Challenge

Increase Nitrogen Use Efficiency Decrease input cost Increase production/Yield

Nitrogen Application

Nitrogen: required in highest quantity. Only preplant application have lowest NUE. Top-dress or side-dress mid-season N applications can

increase NUE (>50%). Fall N application has higher risk of N loss. Spring application can minimize risk and optimize

profitability regardless of tillage (Vetsch and Randall, 2004).

Nitrogen related facts Optimum N rate and NUE changes from year to year.

0 50 100 150 200 2500

2

4

6

8

10

12

14

16

f(x) = − 0.0114034013944196 x + 6.1159539638405R² = 0.116258206654275

f(x) = 0.019879677243769 x + 5.79616716875192R² = 0.293346145128153

Central Great Plains, (1958-2010)

High N

Optimum N rate, kg ha-1

Yie

ld,

Mg h

a-1

Free Environmental N: Total Atmospheric N

Source: National Atmospheric Deposition Program, 2014

Soil organic matter, N supply

The pattern of supply of N made available through net mineralization of soil organic matter N at three sites in Ireland.(Humphreys et al., 2002)

Current Oklahoma State University Approach

Nitrogen Rich Strip OSU GreenSeeker Sensors/Pocket Sensors Variable Rate Applicator Sensor Based Nitrogen Rate Calculator Wheat and Corn Algorithm Web-Based N recommendations Grain Protein Optimizer Ammonia Loss Calculator GreenSeeder Hand Planter

Nitrogen Rich Strip

An area of field with high rate of nitrogen or non-N limiting conditions.

40-50 pounds N/acre, over the average rate. 10 ft wide, 300 ft long. Simple, affordable. Starting from preplant application to 30 days planting

wheat.

Nitrogen rich Strip

Compare N Rich with farmer practice (visual difference)

Sensors to calculate needed N Mid-season N application Approach helps determine N coming from the

environment Minimize environmental damage from excess N

N Rich Strips

Conrad, Montana

N Rich Strip tells You:Yes, I need Nitrogen: If you see strip.No, I do not Need any: If you don’t see Strip.

Cow pox, farmers field

Source:www.osunpk.com

OSU GreenSeeker Sensors/Handheld Sensors (1992-2002)

Measure crop vigor through Normalized Difference Vegetative Index (NDVI).

NDVI is calculated using the equation.

NDVI = NIR ref – red ref / NIR ref + red ref

NDVI values range from 0-0.9. Values near 0.9 are likely non limiting N/healthy plant,

OSU GreenSeeker Sensors/Pocket Sensors (1992-present)

OSU Commercial release GreenSeeker™ in 2002. Optical Sensor/active sensor based technology Emits near infrared and red light which is reflected by

the crop Pocket sensors are more affordable, portable and

lower cost (500 $)

Comparison of NDVI reading

N rich strip Farmers Field

GreenSeeker Sensor

GreenSeeker Handheld Sensor

Variable Rate Technology

Sensor Based Nitrogen Calculator (SBNRC)

GreenSeeker NDVI data (wheat, corn, other crops). Yield potential for a crop is identified using NDVI and

planting date (can then compute GDD) INSEY = NDVI (each date) / (GDD) days from planting

Where GDD= Growing Degree Days from planting Guides producer to apply the optimum N rate

Sensor Based Nitrogen Rate Calculator

United States Outside the States

US Grain Belt-Winter Wheat US-Spring Wheat-Rainfed US Grain Belt-Corn(Rainfed and Irrigated)

S.Australia E.Australia Mexico-Spring Wheat-RainfedBrazil

Bermudagrass-ForageWheat-Forage-PastureGreat Plains, Kansas-SorghumMinnesota, Ohio- CornNorth Central-CottonSouth West Irrigated-Cotton

ArgentinaCanada- Spring Wheat, CanolaIndia-Rice, Spring WheatKenya Rice-Dominion Farms Colombia-Corn Zimbabwe-Corn

Nitrogen Fertilization Algorithm

YP0: Estimate grain yield potential using NDVI and cumulative GDD

RI :N Responsiveness estimated using NDVI in the N Rich Strip and NDVI in the farmer practice or check

CV: Coefficient of variation determined from NDVI sensor readings collected in each plot

Response Index

Yield response to additional N changes N responsiveness = Response Index (RI) RI = Grain yield (Highest N rate or N rich Strip)/Grain

yield (Check 0-N) In season RI : Highest NDVI / NDVI from check N response (RI) changes each year

Response Index

Long term Wheat experiment, Lahoma OK

Response Index

Long term Corn Experiment (1971-2010) Mead, Nebraska

Yield potential and nitrogen response are independent

(Arnall et al., 2013, Agron J. 105:1335-1344)

Optical sensor based Winter Wheat Algorithm

INSEY = NDVI/(days where GDD>0) YP0 = 590exp(INSEY*258.2)

RI = 1.69(NDVI168kgN/NDVI28kgN) - 0.7

YPN = YP0 * RI N rec = ((YPN-YP0) * Grain N)/ fertilizer N efficiency Assumptions:

Grain N = 2.39%

Fertilizer efficiency = 50%

Max Yield = (local cap determined by the producer)

Optical sensor based algorithm for Corn N fertilization

OSU Maize Algorithm

YP0=1291*(EXP(NDVI/Sum of GDD*2649.9) V8 to V12

RI = NDVI- N Rich Strip/ NDVI – Farmer Practice YPN = YP0 * RI N Rate = ((YPN – YP0)* 0.0125)/expected fertilizer use

efficiency

Extension: Oklahoma

More than 500, 000 acres in Oklahoma use N rich Strip

Producers have adopted this technology after seeing the success of their neighbors

Use of GreenSeeker sensor has been a key in Oklahoma

Saving 10 $/acre (Either cutting N rate or gaining yield by increasing N rate)

United States

N rich strip used for different crops rice, cotton, wheat, corn soybean etc.

Louisiana Kansas, Nebraska, Arizona, Iowa Montana Arkansas, Missouri etc. more than 35 US states are using GreenSeeker sensing technologies.

Around the world

NGO’S effective for the extension CIMMYT (Mexico, India, China,) CIAT,CARE, CGIAR OSU Nitrogen Fertilization Algorithm (Wheat and Corn)

are used in Argentina, China and India USAID: Grant allowed GreenSeeker Sensors to be

delivered in China, India, Turkey, Mexico, Argentina, Pakistan, Uzbekistan, and Australia.

Mexico

Mexico

2011-2012

The GreenSeeker Sensor Calibration program in Mexico

N savings Using GreenSeeker In Yaqui Valley, Mexico

Average wheat yield 2011-2012 : 7.2 t/ha Average N rate 250 kg/ha Savings: 68 kg N/ha 13.5 pesos/kg N= 918 pesos/ha ~ 70$/ha While maintaining the same yield By 2012 = 4000 ha

Australia farmer using Green Seeker

Australia

Africa

India

N Rich Strips guides to additional N application Yield potential can be predicted in corn, wheat,

and rice (biomass produced per day). Response to applied N is variable from year to

year and can be predicted. N rate changes from year to year. Nutrient removal is tied to yield level. Need to account freely available N in our N rate.

Conclusion

Thank You