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Understanding Agronomy. Plant Nutrients and Fertility. Objectives Identify essential nutrients for plant growth ; Distinguish between micronutrients and macronutrients ; Discuss the nitrogen cycle and its effect on plant nutrition ; Discuss the role of pH in plant nutrition ; and
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Plant Nutrients and Fertility • Objectives • Identify essential nutrients for plant growth; • Distinguish between micronutrients and macronutrients; • Discuss the nitrogen cycle and its effect on plant nutrition; • Discuss the role of pH in plant nutrition; and • Explain the use of fertilizers
Essential Nutrients for Plant Growth • Nutrientsare substances that living organisms require for life and growth • There are 16 nutrients required by growing plants • Some are gathered from the air while others are found in the soil
Essential Nutrients for Plant Growth • Stomata are the pores found on plant leaves • They help with nutrient uptake and cooling • Elements obtained through stomata are carbon, hydrogen, and oxygen • Roots are used to acquire nutrients like nitrogen, phosphorus, potassium, calcium, and sulfur • What has to happen before these elements can be absorbed by the roots? • They must be dissolved in water first
Essential Nutrients for Plant Growth • 16 essential nutrients • Carbon – C • Boron – B • Hydrogen – H • Oxygen – O • Phosphorus – P • Potassium – K • Nitrogen – N • Sulfur - S • Calcium – Ca • Iron – Fe • Magnesium – Mg • Chlorine – Cl • Manganese – Mn • Molybdenum – Mo • Copper – Cu • Zinc - Zn C.B. Hopkins Café Mighty good Closed Monday Morning see you Zen C.B. HOPK i NSCaFéMighty good Closed Monday Morning CuZen
Distinguish between micronutrients and macronutrients • First, there are two major nutrient categories • Mineral and Non-Mineral • Carbon, hydrogen, oxygen, and nitrogen are all non-mineral nutrients
Distinguish between micronutrients and macronutrients • How are micro and macro nutrients different? • It is based on how much plants need • Macronutrients are needed in larger quantities • Micronutrients are needed in smaller amounts
Distinguish between micronutrients and macronutrients • Macronutrients: • Primary • Nitrogen, Phosphorus, Potassium (N-P-K) • Secondary • Calcium, Magnesium, Sulfur
Distinguish between micronutrients and macronutrients • Micronutrients • The remaining 10 elements
The Nitrogen Cycle • Nitrogen Cycle is the movement of nitrogen from the atmosphere to soil to organisms and back • Nitrogen can be put into the soil in various ways • Chemical and organic fertilizers • Decomposing organisms • Aerating • Lightning strikes
The Nitrogen Cycle • What do legumes do that is so special? • Fix nitrogen from air in the soil • Symbiotic relationship with bacteria • They convert nitrogen gas (N2) into ammonium ions (NH4+) What the heck is that?
The Nitrogen Cycle • The bacteria pull in N2 while they decompose dead plant matter • During that process N2 is converted into NH4+ • The ammonium ions become available to the plant when the bacteria dies
The Nitrogen Cycle • Are we actually putting down N2 when we fertilize with ‘nitrogen’? • No • We are either putting down NH4+ or nitrate • Usually NH4+ is converted to another form of nitrogen called nitrite by Nitrosomas Bacteria • Nitrite cannot be utilized by plants
The Nitrogen Cycle • Nitrite must be converted • There’s a bacteria for that • Nitrobacter Bacteria convert nitrite into nitrate • That is called nitrification
The Nitrogen Cycle • To finish the nitrogen cycle we need denitrification • Happens when soil is saturated with water. • Bacteria convert nitrate into N2 and it escapes into the atmosphere. • Nitrogen can also be lost when • The plant uses it • Leaching occurs
pH and Plant Nutrition • How can pH affect a plant’s nutrition? • Certain nutrients become unavailable to a plant when the pH gets too high or low • It greatly affects N-P-K • Most plants want a soil pH between 5.5 and 8.0
pH and Plant Nutrition • How can you increase pH? (more basic) • Add limestone • How can you decrease pH? (more acidic) • Add sulfur or gypsum
Using Fertilizers • Fertilizers are materials added to the soil to provide a plant with needed nutrients • Two categories • Complete • Contain all three primary macronutrients • What are they? • Incomplete • Do not contain all three primary macronutrients 12-12-12 Nitrogen – Phosphorus -- Potassium 18-46-0
Using Fertilizers • Do the N-P-K numbers always have to add up to 100%? • No • The remainder is filler • Filler will provide for more even coverage of the fertilizer • It is composed of other macro and micronutrients
Using Fertilizers • Selecting your fertilizer • First, determine which nutrients are not readily available • How? • Three different methods
Using Fertilizers • Visual observation • You look at the plant • Pale leaves – nitrogen deficient • Stunted growth, purplish spots on leaves – phosphorus deficient
Using Fertilizers • Soil Testing • Which nutrients are really in your soil? • Some simple tests • Send to a lab for more precise results
Using Fertilizers • Tissue testing • Which nutrients are really available to the plant? • Sometimes nutrients are in the soil, but not available