Post on 21-May-2022
MSU Extension Beginning Farmer Webinar
beginner farmiMisuse
‘Starting with Fertilizer Basics’
George Silva
MSU Extension Educator
Fertilizer Basics
Crop health and misuse
Inorganic
versus
Organic
Soil test
Information
Role of
Fertilizer
Fertilizer
Recommendations
Essential plant
nutrients
Fertilizer
Types
Maximizing
fertilizer
returns
4 R
Stewardship
Outline
Fertilizer/crop/
soil interaction
What are fertilizers
• Materials applied to plants to supply one or more nutrients
essential for growth (natural or synthetic, organic or inorganic,
solid or liquid)
• Usually fertilizers are used to supplement
nutrients provided by the soil
If sufficient nutrients are available in the soil then fertilizers are not
required (testing the soil will save money)
Role
• Fertilizers play a vital role in global food production
• Account for about 40-60% of the total food production
• Expensive item in the cost of production ($150/acre)
Fertilizers do not remedy inherently poor soils
(Eroded, compacted, poor structure or drainage)
Misuse
Misuse of fertilizers can cause contamination of the
environment (groundwater, surface water, greenhouse
gas emissions, etc.)
Concerns for Michigan and the Great Lakes environment Phosphorus contamination of surface water Nitrate contamination groundwater (drinking water)
Photosynthesis - nutrients, water, sunlight
Plants are primary food producers – animals rely on
General crop response to fertilizer
Macronutrients – Nitrogen (N), Phosphorus(P), and Potassium(K)
Required in large amounts and likely to be deficient (BIG 3)
Secondary Nutrients – Calcium (Ca), Magnesium(Mg) and Sulfur(S)
Required in large amounts but less likely to be deficient
Micronutrients – Manganese (Mn), Zinc (Zn), Boron (B), Copper (Cu), Iron (Fe), Molybdenum (Mo), chlorine (Cl), Nickel (Ni) Required in trace amounts
17 Essential Plant Nutrients
Carbon (C), Oxygen (O), and Hydrogen(H) are derived from atmospheric carbon dioxide and soil water
Role of Plant Nutrients Constituent of cell, DNA and cell wall
Cell division
Essential for chlorophyll functioning
Protein (enzyme), sugar, starch and hormone
synthesis
Seed formation
Stress resistance (insect, disease, drought)
The Big 3 Nutrients – Yield Limiting
Every year to most crops - Largest demand and sales
Crop health: Nitrogen deficiency symptoms
Uniformly light green or
yellowing of leaves starting from
the older leaves
Phosphorus deficiency symptoms
Purple coloration early in the season
Potassium deficiency symptoms
Sulfur deficiency symptoms
Manganese (micronutrient) deficiency symptoms
Yellowing between leaf veins
Nutrients are absorbed by the root hairs
Three-way Interaction
Fertilizer
Crop
Soil
• Some fertilizers gets attached to soil particles
• Some are lost to the environment
• Some crops highly responsive to fertilizer
• Some crops prefer certain soils
Most plant nutrients are positively charged
Chemistry 101:
Nutrients are absorbed as ions (+ or -) in solution
Humus and Clay Particles - Nature’s special!!
++
+
++
+
++
++
+
NH4+
NO3-
Most plant nutrients are positively charged
K+
K+ NH4+
Humus and Clay Particles - Nature’s special!!
Clay is rich in nutrients!!
Humus and Clay Particles - Nature’s special!!
Cation Exchange Capacity –Ability to retain nutrients
Negatively charged clay and humus particles
Measured when soil is tested
Types of fertilizers
• Solids, liquids, gases
• Organic versus synthetics
• Fast acting versus slow acting
• Crop responses to liquid and dry fertilizer are similar,
provided the amount and placement of nutrients are
the same.
Fertilizer Bag
By Weight
Fertilizer Grade – Guaranteed nutrient content
Fertilizer Grade –Minimum guarantee on a weight basis – N, P, KBoth granular and liquid fertilizer
A 100 pound bag of 10-10-10 fertilizer:
• 10 pounds nitrogen
• 10 pounds phosphate
• 10 pounds potash
applied on 1000 sq.ft. of lawn
Q. If you purchased a 50 lb bag of 10-10-
10 fertilizer,
how many pounds of N and K are in the
bag?
Answer: 5 lb N, 5 lb P, 5 lb K
If you know the area of your lawn, then you can apply
what is recommended to you
Liquid fertilizers
• UAN (Urea-ammonia nitrate) 28%N
• 10-34-0 (Ammonium polyphosphate)
Analysis Weight (lb) per US Gallon
28-0-0 UAN 10.65
10-34-0 11.60
Example 1. 28-0-0 fertilizer used as starter or sidedress
100 lbs of 28-0-0 contain 28 lbs N
10.65 lbs (1 gal) contain (28/100) * 10.65 = 2.98 lb N
10 gal of 28-0-0 will contain 2.98* 10 = 30 lb N
Common Nitrogen (N), Phosphorus (P) and Potassium (K) Sources
Common Fertilizer Grade NutrientCost
$/ton fertilizer*
Urea 46-0-0 N 564
Anhydrous Ammonia 82-0-0 N 785
UAN 28% N 385
Monoammonium Phosphate (MAP) 11-48-0 N and P 704
Muriate of Potash 0-0-60 K 630
Bulk6-24-24 N, P and K 627
Bulk 16-35-5 + Zn + S N, P, K, Zn, S 726
Inorganic (synthetic) versus Organic Fertilizers
Fast Acting (Soluble) Slow Acting (Microbes have to decompose)
Easy to measure and apply Large quantities
Excess – burn plants Excess – burn plants
Excess – contaminate environment Excess – contaminate environment
Smell – attract rodents and flies
Adds organic matter – WHC of soil
Form of nutrient absorbed by the plant is the sameNitrate (N03
- ) Ammonium (NH4+), Phosphate (PO4
--- ) Potassium (K+ ) ions
Foliar fertilization
• Application of nutrients to foliage
• Only small quantities can be supplied
• Can be used with irrigation water (fertilgation)
• Effective as rescue treatments
• Application of nutrients to foliage
Organic Agriculture
No synthetic pesticides
No synthetic fertilizer
No synthetic hormones or growth regulators
Need to be certified
Does organic produce have more nutritive value than conventional?
Organic fertilizers
Cattle Manure Compost Blood meal Bone meal
Corn gluten meal Greensand Seaweed extract Fish meal
Liming
• Amendment to neutralize soil acidity (pH)
• Generally finely ground limestone
• Applied following a soil test recommendation
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Low pH=Acidic High pH=Alkaline
Neutral
Battery
acidVinegar Orange
juice
Pure
waterBaking
sodaAmmonia Bleach Lye
Acid or pH Scale (0-14)
Measure of acidity (hydrogen ion concentration)
Liming – Excellent investment
Liming – Excellent investment
MSU Extension Pub: E 471 Lime for Michigan Soils
Effect of soil pH on nutrient availability
on a mineral soil
Liming
• Amendment to neutralize soil acidity (pH)
• Generally finely ground limestone
• Applied following a soil test recommendation
The 4 ‘Rights’ of Fertilizer Use. Was the crop fertilized properly?
Soil testing every 3-4 years
Nutrient Management -Determining right rate is critical
Soil testing – basis for fertilizer recommendations
Deficiency symptoms appear too late and not entirely reliable
MSU Soil Test Lab Report
Big ‘three’ –N, P, K
Below optimum
(Buildup )
Optimum
(Maintenance)
Above Optimum
(Drawdown)
Analysis
*
Recommendations
Background
Footnotes
(Buildup) (Maintenance) (Drawdown)
Features:
• Soil pH• Nutrient levels• CEC• Lime recommendation• No test for N• N, P, K, Mg and micronutrient
recommendations for the expected yield
• N and P as starter
*
When P205 exceed 60 ppm the starter P is turned off
Only starter N is needed
*
Mg < 50 ppm in fine
textured soils or
<35 ppm on sandy soils
When Mg is < 3%
exchangeable bases
When exchangeable K
exceeds Mg
*
*
*
*When pH exceeds 7 -testing for Mn and ZnIs suggested
Optimum pH range is 6.5-6.8
The 4R Nutrient Stewardship Concept to
satisfy all stakeholder concerns
Nitrogen placement on potatoes 6-8 weeks
Fertilizer Practice Guidelines P and K are applied at planting or seeding or beginning
of the season (stay in the soil)
N – Split application (subject to loss)
Nitrogen Application
Vegetables and Flowers: Two third of N is applied at
planting. The balance one third is applied 6 weeks
after planting.
Lawns: Split N over 4 applications during the year
(April, May, September, November).
Add water after fertilizer application*
Interpreting Soil Test Results
Add 75 lb/1000 sq ft of lime in the fall or early spring
Add 20 lb 10-10-10 grade/1000 sq ft at planting
(equates to adding 2 lb of N, P, and K)
Add 2 lb urea (46-0-0) grade/1000 sq ft 6 weeks
after planting
(equates to total 3 lb N, 2 lb P, and 2 lb K)
Irrigate
Note:Consider convenience, price and timing
Nutrient Recommendations for Fruit Crops in Michigan
MSUE Pub. E 852 Fertilizing Fruit Crops 1996
Nutrient management in fruit crops
Plant tissue analysis is the most reliable tool for nutrient management in established orchards
Roots reach depths below the soil probe
Optimal nutrient concentrations for leaf and petiole have been established
Soil tests - Pre-plant fertilizer applicationsdetermine soil pH every three years or so
Nutrient management in fruit crops
• Tissue analysis in 2-5 years
• MSU soil testing lab offers the service
Seven “Fail-Safe” Steps for Maximizing
Fertilizer Returns
1. Soil test to determine need
2. Lime adequately
3. Provide other inputs and grow best crop possible
4. Use “right” rate, source, timing and placement
5. Irrigate after adding fertilizer
6. Maximize efficiency /avoid losses
7. Avoid overuse
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