Why? - utcrops.com Mid TN - Implementing variabl… · Why? How? What? • WHY – Field...

Why?

How?

What?

• WHY – Field variability exists

• HOW

– Assess spatial variability

• WHAT – Variable rate applications

Field Variability

Why?

How?

What?

Field Variability

Why?

How?

What?

Information provided by: Dr. Wes Porter, UGA

Economic Benefit

Why?

How?

What?

Environmental Benefit

Why?

How?

What?

Assessing Field Variability

• Soil Sampling

• Normalized Yield Data

• Soil Electrical Conductivity (EC)

• Topography

• Soil Maps

Why?

How?

What?

Soil Sampling

Why?

How?

What?

Grid

G

Grid-Point Sampling Grid-Cell Sampling

Grid-Point – fields with little variability

Grid-Cell – fields with variability

10 – 15 soil cores

Soil Sampling

Why?

How?

What?

2.5

2.5 5

10

Soil Sampling

Why?

How?

What?

Soil Sampling

Why?

How?

What?

Grid Resolution

Soil Sampling

Why?

How?

What?

Grid Resolution – P2O5

2.5 acre grid 5 acre grid

150 bu corn

Soil Sampling

Why?

How?

What?



P2O5 (lbs/A)

Area (A)

DAP (lbs)

Area (A)

DAP (lbs)

Low 120 4.7 1226 8.1 2113

Medium 60 12.7 1657 13.9 1813

High 0 21.6 0 17 0

Total 2883 3926

Soil Sampling

Why?

How?

What?



P2O5 (lbs/A)

Area (A)

DAP (lbs)

Area (A)

DAP (lbs)

Low 120 4.7 1226 8.1 2113

Medium 60 12.7 1657 13.9 1813

High 0 21.6 0 17 0

Total 2883 3926

Using 2.5 acre grid vs. 5 acre grid saved this producer

$8.56/ac and 480 lbs P2O5

Soil Sampling

Why?

How?

What?

Grid Resolution – K2O


150 bu corn

Soil Sampling

Why?

How?

What?



K2O (lbs/A)

Area (A)

Potash (lbs)

Area (A)

Potash (lbs)

Low 120 11.1 2220 14.2 2840

Medium 60 23.1 2310 20.2 2020

High 0 4.6 0 4.5 0

Total 4530 4860

Soil Sampling

Why?

How?

What?



P2O5 (lbs/A)

Area (A)

DAP (lbs)

Area (A)

DAP (lbs)

Low 120 11.1 2220 14.2 2840

Medium 60 23.1 2310 20.2 2020

High 0 4.6 0 4.5 0

Total 4530 4860

Using 2.5 acre grid vs. 5 acre grid saved this producer

$2.52/ac

• Normalized Yield Data

• Soil Electrical

Conductivity (EC)

• Topography

• Soil Maps

Defined Management Zones

Zone Management

Why?

How?

What?

Yield Maps

Why?

How?

What?

You Need Multiple Years of Yield Data

𝒙𝒙 = 𝒚𝒚𝒚𝒚𝒚𝒚𝒚𝒚𝒚𝒚 𝒑𝒑𝒑𝒑𝒚𝒚𝒑𝒑𝒑𝒑 𝒙𝒙� = 𝒂𝒂𝒂𝒂𝒚𝒚𝒂𝒂𝒂𝒂𝒂𝒂𝒚𝒚 𝒚𝒚𝒚𝒚𝒚𝒚𝒚𝒚𝒚𝒚

𝑵𝑵 = 𝒙𝒙𝒙𝒙�∗ 𝟏𝟏𝟏𝟏𝟏𝟏

Yield Maps

Why?

How?

What?

Field Average 174 bu/ac

Yield Maps

Why?

How?

What?

𝟏𝟏𝟏𝟏𝟏𝟏 𝒃𝒃𝒃𝒃/𝒂𝒂𝒂𝒂𝟏𝟏𝟏𝟏𝟏𝟏 𝒃𝒃𝒃𝒃/𝒂𝒂𝒂𝒂

= 𝟏𝟏.𝟏𝟏𝟏𝟏

𝟏𝟏𝟏𝟏𝟏𝟏 𝒃𝒃𝒃𝒃/𝒂𝒂𝒂𝒂𝟏𝟏𝟏𝟏𝟏𝟏 𝒃𝒃𝒃𝒃/𝒂𝒂𝒂𝒂

= 𝟏𝟏.𝟖𝟖𝟏𝟏

Yield Maps

Why?

How?

What?

Average yield by zone

% of Field Corn Beans Cotton Low 18 91 45 617

Medium 59 132 63 910 High 23 144 70 1025

Soil EC

Why?

How?

What?

6 – 23 mSiem/m

5 – 224 mSiem/m

Soil EC

Why?

How?

What?

Topography

Why?

How?

What?

Soil Type

Why?

How?

What?

Why?

How?

What?

Data-Driven Decisions

Variable Rate Applications • Fertilizer • Seeding • Irrigation • Other

– Chemical application – Manure spreading

Why?

How?

What?

If we used blanket rates of…

2500 lb/A (+$6/A)

200 lb/A (+$5/A)

30 lb/A (+$2/A)

VR Fertilizer


2000 lb/A (+$8/A)

200 lb/A (-$2/A)

150 lb/A (+$6/A)

VR Fertilizer


2750 lb/A (+$4/A)

200 lb/A (+$9/A)

30 lb/A (+$4/A)

VR Fertilizer

VR Seeding

Why?

How?

What?

VR Seeding

Why?

How?

What?

2013

2014

*No statistical differences were observed between seeding

rates

Average Soybean Yield

by Seeding Rate

Why?

How?

What?

VR Seeding

Why?

How?

What?

VR Seeding Inside versus Outside of Center Pivot

• Basically it is being precise with our irrigation applications by knowing: – When to Irrigate – How often to Irrigate (frequency) – How much to irrigate – Where (spatially) to irrigate

VR Irrigation

Why?

How?

What?


• Cannot realize benefits from variable rate fertilization, lime, seed, etc. if we do not first properly manage water.

• Water conservation and water use efficiency are critical issues.

• Already regulatory actions restrict agricultural water use.

• It is EXPENSIVE to irrigate.

VR Irrigation

Why?

How?

What?


• Variable rate irrigation is the controlled rate and placement of water based on measured conditions.

• In many cases water is wasted throughout a field due to: – Overlap – Field variability – Wet or low area – Poorly drained soils/Well drained soils – Water being applied to a non-crop area

• Management control zones are developed based on field conditions, crop needs, and feasible control size.

VR Irrigation

Why?

How?

What?


VR Irrigation

Why?

How?

What?


• Implement widths • Soil EC • Soil Type • Elevation • Field Size • Irrigation Tower Length • Single or Multiple Crops

VR Irrigation – Zone Development

Why?

How?

What?


• How large do I want my management zones? – What is feasible for my operation? – What type of field resolution do I want? – How long is my irrigation tower? – How many nozzles do I have? – How wide do the management zones need to be? – The higher the resolution the more control equipment

required. – Two nozzles per zone would be the minimum. – Keep in mind that smaller zones can be treated uniform

and “merged”, but larger zones cannot be divided once the control system is implemented.

Why?

How?

What?



• How am I currently scheduling my irrigation? – Using VR will require a

more intensive management and scheduling strategy.

– Moisture sensors in every zone? In similar zones?

– Do I want to work towards an automated system or would I be better off calculating and entering each zones needed rate separately?

Why?

How?

What?



Why?

How?

What?



Soil Electrical Conductivity, at

planting

Aerial Photography,8

Weeks After Planting

Seed Cotton Yield

Why?

How?

What?



Yield Data • Soil fertility, type, etc. • Disease or insect pressure • Variety differences • Poorly drained areas • Compacted areas • Does not point out the yield limiting variable, it

only indicates the response to it.

Why?

How?

What?



• Identify and quantify yield variability within fields. • Use the identified zones to make management zones

and decisions. • Use the management zones to adjust crop inputs.

Why?

How?

What?



• A VR system requires: – A control system for each developed zone

• Can consist of electronic or pneumatic valves – A control software for inputting the developed

zones and supplying a control signal – Differential GPS (for accurate location of the

system) – Either a variable frequency pump or pressure relief

to account for changes in flow and pressure due to varying zones.

Why?

How?

What?


VR Irrigation – Mechanics

• Total area = 228 ac

• Not cropped area = 84 ac (37%)

• 84 ac × 12 in irrigation = 1008 ac-in ► $12,096

► 27.3 million gallons / year

VR Irrigation

Why?

How?

What?


Recap • Why?

– Spatial variability • How?

– Assessing variability • What?

– Variable rate applications

Why?

How?

What?

Take Home Message

Why?

How?

What?

• Variability exists in all fields – OPTIMIZE! • VR fertilizer application places the right

rate at the right place • Zone management requires precision ag

data • VR seeding has the potential to

maximize profitability • VR irrigation conserves water and lowers

irrigation costs

Lori Duncan Biosystems Engineering

UT Extension [email protected]

(865) 974-7111

Mike Buschermohle Biosystems Engineering

UT Extension [email protected]

(865) 974-7142

mailto:[email protected]

mailto:[email protected]

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