Fertilizers and Plants Plant Environment Fertilizers and Plants

Objectives Determine the roles of plant nutrients for plant growth. Describe the effects of external factors (water, light, and temperature) on plant adaptation and development Identify optimum soil and water pH for ornamental and forage crops. Identify the hardiness charts to determine temperature zones for areas within the state.

Primary Elements Available nutrients must be in soluble form before plants can use them Absorbed by the roots May come from organic or inorganic fertilizers

Plant nutrients Macro-nutrients – those needed in large amounts Primary Macronutrients – N, P, & K Secondary Macronutrients – Ca, Mg, and S Micro – nutrients – those needed in very small amounts

The major nutrients are N, P, K They are the main ingredients in commercial fertilizers. They are displayed by three numbers on the front of the bag. 10-10-10, the mixture is 10% N, 10% P, and 10% K. The total is 30% elements. The other 70% is a filler like lime.

Nitrogen Has the most noticeable effect on plants Uses Encourages aboveground growth Gives dark green color to the leaves Produces soft, tender, leafy growth for crops such as lettuce and spinach

Nitrogen Cont. Too Much Too Little Lowers the plant’s resistance to disease Weakens the stem Lower the quality of fruit Delay plant maturity and flowering Too Little Yellow or light green in color Stunted in root and top growth

Phosphorus Uses Encourages plant cell division Essential for flower and seed production Hastens maturity Encourages root growth Makes potassium more available Increases resistance to disease Improves the quality of grain, root, and fruit crops

Phosphorus Cont. Too much Too little Cause container plants to dry out Cause a white deposit on soil surface Too little Purple coloring on the undersurface of the leaves Reduced flower, fruit, and seed production Increased susceptibility to cold injury Increased susceptibility to plant disease Poor quality fruit and seeds

Potassium Uses Resistance to disease Strong root system Essential for starch formation Chlorophyll Efficient use of carbon dioxide

Potassium Cont. Too Little Cause plants to appear dry and scorched on the edges with irregular yellow areas on the surface

Secondary macronutrients Calcium Needed for cell walls to form Too little – cell tissue breaks down Deficiency symptoms – reduced root growth Magnesium Essential part of the chlorophyll molecule Deficiency symptoms – pale green color Sulfur Essential for chlorophyll formation

Micronutrients Iron (Fe) Manganese (Mn) Copper (Cu) Zinc (Zn) Boron (B) Molybdenum (Mo) Chlorine (Cl) Cobalt (Co)

Organic fertilizers Refers to material that is living or has come from living organisms. Have low concentrations of N,P, and K. Makes soil loose and workable. Enhances the moisture holding capacity. Enhances the ability of the soil to retain and make elements available. Reduces soil erosion.

Inorganic fertilizers Refers to nonliving materials like chemical salts. These fertilizers are usually easily handled, applied quickly and in concentrated amounts.

Calculating Fertilizer Requirements Complete Fertilizer Container has N-P-K amounts on label Ex. 5-10-15 5% N 10% P 15% K = 30% of fertilizer is nutrients 5% + 10% + 15% = 30% 30% of fertilizer are the nutrients Other 70% = filler Filler usually consists of lime

Calculating Fertilizer by Area N, P, or K content (number on bag) = actual N, P, K 100 x

External factors that affect plants Temperature Light Moisture

Temperature Warm season crops = soils temp >70 Cool Season crops = soil temp < 70 Different crops need different temps to grow Plants have no temperature control mechanism

Light Quantity-amount of light received Quality-amount of light of a certain color that a plant absorbs or reflects Light duration- length of day

Moisture Water needed for photosynthesis Humidity affects plant growth Water is a solvent for nutrients and other materials needed by the plant

Limiting Factor Concept Optimum Growth Conditions are desired for crops Limiting factor is something that prevents plant from growing to its optimum yield

Optimum soil and Water pH The effects of soil pH are determined by the solubility of minerals and nutrients. Fourteen of the seventeen essential nutrients come from the soil solution. Most minerals and nutrients are available in acid soils than in neutral or alkaline soils Some nutrients become unavailable to plants at low or high pH levels

Plant Hardiness Zone Maps that depict the hardiness zones for plants throughout the United States Shows the average lowest winter temperatures for a certain area

Plant Hardiness Zone Map Louisiana Plant Hardiness Zones 8A/ 8B =10-15/15-20 F 9A/ 9B = 20-25/25-30 F