Unit 6 - Lawn Fertilization

What are the four major nutrients for turf?

• Nitrogen

• Phosphorous

• Potassium

• Iron

Effect of Nitrogen in turf:

• Vegetative growth.

• Shoot density.

• Colour.

• Root growth.

Effect of Phosphorous on turf:

• Root growth

• Establishment

• Maturation

• Reproduction

Effect of Potassium in turf:

• Improves stress tolerance

Effect of Iron in turf:

• Chlorophyll production

• Vegetative growth

Deficiency symptoms of Nitrogen:

• Stunting and chlorosis on older leaves.

• Plae green → yellow grass

Deficiency symptoms of Phosphorous:

• Poor root development

• Dark green colour — towards pruple.

• Stunted growth and reduced tillering.

Deficiency symptoms of Potassium:

• Stunting

• Scorched leaf margins

• Reduced resistance to cold, heat, disease, drought.

Deficiency symptoms of Iron:

• Interveinal chlorosis on new blades.

In what type of soils is Iron deficiency most common?

In alkaline, waterlogged, or high organic matter soils — it is tied up and not available.

Fertilizer application rate of City of Kamloops and TRU:

½ lbs N per 1000 ft2

How many fertilizer applications per year in the interior?

Minimum 2 applications

How many fertilizer applications per year in coastal areas?

Minimum 3 applications because of longer season and more leaching from rainfall.

Timing of fertilization in the interior (granular):

• 2 times a year:

  • Early spring (April)

  • Late summer (August).

• 3 times a year:

  • Mid to late May

  • Mid August (lowest N)

  • Late October / early Novemenber, after grass goes dormant.

How often do you need to fertilize golf courses?

Weekly at ¼ lbs N per 1000 ft2.

What element high in do coastal applications use?

Fertilizers high in potassium — to help with stress.

What do coastal applications do different than the interior?

• Fertilize more frequently because of longer season and rainfall.

• Routinely apply lie to raise soil pH.

What are some rate and timing variables for fertilizing?

• Mower clippings — equal to 1-2 lbs of N.

• What turfgrass species you are growing.

• Climate

• Level of culture desired.

• Soil type

• Irrigation rate of the site

The three general groups of Nitrogen fertilizers are:

• Quick release synthetics

• Slow release synthetics

• Organic sources

Examples of quick rlease synthetic fertilizers:

• Urea (46-0-0)

• Ammonium nitrate (34-0-0)

• Ammonium sulfate (21-0-0-24S)

Characteristics of quick release synthetic fertilizers:

• High water solubility

• Rapid response

• High potential for foliar burning

• Easily leached

• Inexpensive

Examples of slow release synthetic fertilizers:

• Sulfur coated Urea

• Polymer coated Urea

Advantages of slow release synthetic fertilizers:

• Provides longer response.

• Provides more even release.

• Nutrient release to turf.

• Easier to schedule maintenance.

Disadvantages of slow release synthetic fertilizers:

• Poor initial performance.

• Slow in cooler weather due to reduced microbial activity in soil.

• More expensive initially.

Characteristics of Urea (46-0-0):

• cheap

• subject to volatilization

Characteristics of Ammonium nitrate (34-0-0):

• contains ammonium and nitrate.

Characteristics of Ammonium sulfur (21-0-0-24S):

• contains ammonium and sulfur.

• sulfur acidifies soil

What slow release synthetic fertilizer is more uniformly released?

Polymer covered Urea

What does the availability of slow release synthetics depend on?

• Type of coating

• Temperature — microbial activity

• Moisture

• Soil pH

• Particle size of the fertilizer

Organic sources of Nitrogen:

• Manure

• Bio soilids

• Composted crop residue

• Humus

Advantages of organic Nitrogen fertilizers:

• Will not burn the grass.

• Very little effect on soil pH.

• Most contain other nutrients.

• May raise soil temperature during cool periods.

• May improve soil conditions (structure).

• Do not leach easily.

Disadvantages of organic Nitrogen fertilizers:

• Low in Nitrogen content.

• More difficult to move, store, and apply.

• Can be expensive.

• May contain undesireable substances — weed seeds, heavy metals.

• Slow initial release rate.

How to apply granular fertilizers?

• Apply when grass is dry.

• If the grass is wet, water fertilizer inmediately to avoid burning of grass blades.

• Irrigate immediately to reduce ammonia gas volatilization.

Equipment for applying fertilizers:

• Drop spreader

• Broadcast spreader

Drop spreader characteristics:

• Good in small areas.

• Easier to miss areas and to have fertilizer burn.

Broadcast spreader characteristics:

• Good on steep grades.

• Much quicker than drop spreader.

• Less potential of misses or burns.

Liquid feeding characteristics:

• Fertilizer mixed with water and applied.

• Done by lawn care companies.

• Faster acting than granular fertilizer.

When do manufacturers recommend applying Weed and Feed?

After the third mowing.