Nutrient Management of Irrigated Alfalfa and Timothy

Ross H. McKenzie

Old Agronomist

Lethbridge

Irrigated Crop Production Conf.

Lethbridge, AB

Jan 19, 2016

Introduction

• Alfalfa and Timothy are excellent crops to include in an irrigated crop rotation.

• Both have high nutrient requirements demands for soil nutrients.

• Both use up to 4 to 5 inches of water for each ton of dry matter produced.

1. Benefits of forage in crop rotation

2. Soil testing and analysis3. Nitrogen and N fixation

4. Phosphorus5. Potassium

6. Sulphur

7. Micro’s

Outline:

Benefits of Alfalfa & Timothyin the Crop Rotation

• Increased soil quality and soil health

• Increased soil organic matter and soil carbon levels

• Improved soil structure

– Increased water infiltration and internal drainage

• Increased soil fertility and increased nitrogen release benefits

– Reduced nitrogen fertilizer requirements for several years after Alfalfa

• Reduced weed and disease pressure

• Increase yields of following crops

Benefits of Forage in a Crop Rotation

Nitrogen Benefit After Alfalfa

• N fertilizer can be reduced by

–Up to 50% the first year after Alfalfa.

–30% the second year after Alfalfa

• Wheat protein increased by up to 2% after Alfalfa

Nutrient Requirements

Alfalfa Nutrient Removal

Nutrient 6 Tons (lbs/ac)MacronutrientsNitrogen (N) 300+Phosphate (P2O5) 60 - 75Potassium Potash (K2O) 250+

Sulphur (S) 30 Calcium (Ca) 150Magnesium (Mg) 30

MicronutrientsBoron (B) 0.4Copper (Cu) 0.06Iron (Fe) 1.5Manganese (Mn) 0.6Molybdenum (Mo) 0.012Zinc (Zn) 0.3

Timothy Nutrient Removal

Nutrient Amount Removed (lbs/ac)5 Tons

Macronutrients:Nitrogen (N) 200+Phosphate (P2O5) 50Potash (K2O) 200Sulphur (S) 25Calcium (Ca) 150Magnesium (Mg) 25

Micronutrients:Boron (B) 0.4Copper (Cu) 0.05Iron (Fe) 1.5Manganese (Mn) 0.5Molybdenum (Mo) 0.01Zinc (Zn) 0.25

Soil Sampling and Testing

Why Soil Test?

• Gives an excellent inventory

–plant available nutrients

–soil chemical factors important for crop production.

• Provides a basis for recommending additional nutrients.

Soil Sampling:

• Depths:

– 0-6”

– 6-12”

– 12-24”

0-6” - N, P, K, S, pH, EC + micro’s*

6-12” - N, P, K, S, pH, EC + micro’s*

12-24” - N, S, pH, EC

* Before establishment

Soil analysis:

• Modified Kelowna extractant is used for:

–NO3-N, P and K

• Don’t use Bray or Olsen methods!!

• CaCl2 is used to extract SO4-S

• DTPA – is used for metal micronutrients – Cu, Fe, Mn and Zn

• Hot water is used to extract Boron

Nitrogen (N) Nutrition of Alfalfa

Nitrogen and Alfalfa:

• N fertilizer is rarely required on established Alfalfa.

• Alfalfa can "fix" its own nitrogen (N) with Rhizobium meliloti, a bacteria that lives in association with roots.

• Bacteria form nodules on the plant roots and convert nitrogen gas (N2) from the air, into a form that plants can use. Alfalfa is effective at fixing N.

• A 6 ton/ac Alfalfa crop can fix up to 300+ lb/ac of N/yr.

Nodules contain bacteria which fix N for Alfalfa growth

N fixation:

• Alfalfa seed must be inoculated with R. meliloti.

• N-fixation by Alfalfa may decline after a stand is 4 or 5 years old.

• Poor yielding stands should be terminated and seeded to an annual crop for several years before being reseeding to Alfalfa.

0 N 180 lb N/ac Urea Spring Broadcast

Timothy – Lethbridge – June 13, 2006

Nitrogen for Timothy

90 Urea N 45 lb N/ac Urea Spring Broadcast

Timothy – Lethbridge – June 13, 2006

135 ESN N 135 lb N/ac AN Spring Broadcast

Timothy – Lethbridge – June 13, 2006

45 AN N 45 lb N/ac Urea Spring Broadcast

Timothy – Lethbridge – June 13, 2006

45 AN N 90 lb N/ac ESN Spring Broadcast

Timothy – Bow Island – June 19, 2006

N Rates for Timothy

• Spring for first cut:

–120 to 135 lb N/ac - very early spring

• Immediately after first cut is off:

–70 to 100 lb N/ac – irrigate immediately after

Timothy Nitrogen Choices• Spring broadcast urea (46-0-0)

– Best option – if broadcast very early in spring (when very when soil is cool !)

– Watch weather forecast and consider volatilization potential

• Spring broadcast ESN

– NO – release rate is TOO SLOW!

• Spring broadcast Agrotain coated urea (46-0-0)

– Higher fertilizer cost for 10-12 days of protection – from volatilization!

– Good option if weather conditions are warm and windy

• Spring dribble banded UAN liquid (28-0-0)

– Good option – but consider volatilization potential – apply in early spring!

– Consider the higher cost of liquid N

– Can add Agrotain to liquid for 10 to 12 days of protection from volatiliztion!

• Spring broadcast Ammonium sulphate (21-0-0-24)

– Short term option – No N loss but will apply S at high rate

– Not preformed well in our winter wheat work

• Ammonium nitrate (34-0-0)

– Best product – BUT must import from USA – Good Luck!!

Phosphorus (P) Nutrition

Phosphorus

• Alfalfa and Timothy have a high requirement for phosphorus (P)

• Most irrigated soils in Alberta are naturally low in plant available P

• Residual P levels vary in irrigated soils

– Many fields have received phosphate fertilizer

– Manured fields usually have adequate P and K

• Soil testing is strongly recommended before establishing Alfalfa to determine P requirements

P Fertilizer Application Before Forage Establishment• A large single application of P fertilizer or the

application of manure or compost before establishing Alfalfa or Timothy is very effective to add P to soil.

• An application of 150 lb/ac of P2O5 before establishment.

• Phosphate fertilizer can be either banded or broadcast-incorporated prior to seeding Alfalfa or Timothy.

Phosphorus Fertilizer – Established Forage

• If soil P is < 90 lb/ac or if P was not applied before establishment

– Apply 50-60 lb/ac of P2O5 (Granular 11-52-0; 12-51-0) broadcast in early spring –every year

– Under moist conditions, Alfalfa and Timothy have feeder roots near the soil surface that can take up broadcast P with reasonable efficiency.

• Can use dribble applied or can fertigate with liquid P fertilizer (10-34-0)

• Manure or Compost is an excellent source of P.

0 P2O5 54 lb P2O5 /ac Spring Band

Timothy – Lethbridge – June 13, 2006

Phosphate Fertilizer – P2O5

2006 Lethbridge – First Cut

0

1000

2000

3000

4000

5000

6000

Yie

ld (

kg

/h

a)

Phosphate Response - Method & Rate

0

30 Br

60 Br

30 Bd

60 Bd

0 + 200

30 Br + 200

60 Br + 200

30 Bd + 200

60 Bd + 200

kg P2O5/ha

Potassium (K) Nutrition of Alfalfa

Potassium

• Alfalfa and Timothy have a high requirement for potassium (K).

• If soil K levels are less that 200 lb/ac of K (Kelowna or ammonium acetate extractable K), in the 0 to 6 inch depth

– K fertilizer is recommended and may need to be coupled with annual applications.

• Most irrigated loam and clay loam soils have adequate soil K!

• K is most commonly deficient on very sandy soils that are more intensively cropped.

• Use a soil test to determine if soil K levels are low or deficient.

Soil Test K Potassium (K2O ) Recommendations(0-6 inches) (lb/ac)

0 – 50 150 – 170 50 – 100 100 - 120 100 – 150 90 – 100 150 – 175 50 – 60

175 – 200 40 – 50

200 – 250 25 – 50

>250 0

Note: Based on the Kelowna or ammonium acetate soil K test method.

Annual Potassium Fertilizer Recommendations for Alfalfa and Timothy.

Placement and Application Options

• Establishment

–Broadcast K to build up soil test K before seeding

• Maintenance

–Apply following harvest to replace removal

–When soil K levels are high

•K fertilizer application can lead to high K levels in forage – which is not desirable!

Sulphur (S) Nutrition

Sulphur – on Irrigated Land

• S fertilizer is rarely required for perennial crops:

–Subsoil is usually relatively high in sulphate-S – roots have access to this S

–Approximately 30 lb S/ac is applied in 12” of irrigation water – in the Sulphate form!

Calcium and Magnesium- Not Needed - in southern Alberta

- Base Saturation method used to predict Ca and Mg is flawed practice.

- Should not be used to make recommendations!

Micronutrient Needs of Alfalfa

Low Soil Levels

Nutrient Low Soil Level

Boron < 0.2 ppm in 0-6” – Soil test is not reliable

Copper < 0.2 ppm in 0-6

Iron < 2.5 ppm in 0-6”

Manganese < 0.5 ppm in 0-6”

Zinc < 0.5 ppm in 0-6”

-Micronutrients are not normally deficient

-Deficiencies may occur on very sandy, low organic matter soils that are intensively cropped!

-If soils test low – try strips first!

Summary

• Nitrogen

– Inoculate alfalfa seed – before seeding

– Timothy – 120-135 lb N/ac in early spring and 70-100 lb N/ac for second cut

• Phosphorus - If soil P is low –

–Apply P2O5 before establishment – 150 lb/ac

–Annual application ~50-60 lb P2O5/ac

• Potassium (Potash fertilizer)

–Only needed if Soil Test K is <200 lb/ac

• Sulphur and Micronutrients – rarely needed!

Ross H. McKenzieLethbridge, Alberta

Phone: 403-328-1001

rossmckenzie@shaw.ca

Questions ?