Mineral Nutrition A discussion in Chapter 5 Are Plants What They Eat? or What is Plant Food?

Sixteen essential elements Carbon, Hydrogen, Oxygen Carbon, Hydrogen, Oxygen Nitrogen, Phosphorus, Potassium Nitrogen, Phosphorus, Potassium Ca Calcium, Mg Magnesium, Sulfur Ca Calcium, Mg Magnesium, Sulfur Fe Iron, Mn Manganese, Mo Molybdenum Fe Iron, Mn Manganese, Mo Molybdenum Cu Copper, Boron, Zn Zinc Cu Copper, Boron, Zn Zinc Cl Chlorine Cl Chlorine C Hopkins CaFe, Mg B Mn CuZn, Cl Mo

Essential Elements: CHO come from air and water All the rest come into plants as dissolved solutes in soil water ­Not only must they be in the soil, they must also exist in a form usable to plants Nutrient usage in plants is categorized by the relative amounts used in plants ­Macronutrients ­Micronutrients

Primary Macronutrients Nutrients used in largest amounts Nitrogen Phosphorus Potassium

Secondary Macronutrients Used in lesser amounts than primary, but still a lot more than micronutrients Calcium Magnesium Sulfur

Micronutrients Minerals used in much smaller amounts Iron, Manganese, Molybdenum Copper, Boron, Zinc Chlorine

Availability by pH levels All nutrient forms are affected by soil pH, but especially the micronutrients. This is why we often have iron- deficient plants in the West.

Nitrogen Can cause rapid vegetative growth Fixed by bacteria on legume plants Absorbed as NO 3 -, NH 4 +, NH 2 + Is easily leached from soils Especially sandy soil

N Fertilizer composition and effect on soil pH

Phosphorus Not very soluble in soil water Does not leach Deficiencies show up as exceptionally dark green or purple leaves Flowering, fruiting, root development, disease resistance

Potassium Easily leached Important in stomata opening and closing, water retention, starch formation, chlorophyll formation Deficiency results in stunted plants, older leaves may wilt, intervenal chlorosis begins at base

Iron Often deficient in plants grown on alkaline soils Not due to lack of Fe in soil, but unavailable form Intravenous yellowing progressing to white foliage Many micro fertilizers are formulated as ‘chelates’

Chelate Greek, meaning claw Large organic molecules that hold specific cations allowing them to be absorbed and used by plants Chelates hold Fe, Mn, Zn, and S and prevent them from reacting with inorganic anions Sequestering agents

Fertilizers Divided into 2 common types ­Organic ­Inorganic

Organic Fertilizers Derived from decomposition of animal wastes or plant products Also act as soil amendments or conditioners Nutrients are released slowly through decomposition ­Slow and unreliable in cold soil Expensive for the amount of nutrients they actually contain

Inorganic Fertilizers Come from mined and manufactured raw materials Much more concentrated than Organics Can be formulated as fast-release or slow- release As far as N goes, most plants use the same form (NO 3 - ), regardless of how it gets there Can cause rapid depletion of soil OM

Fertilizer Forms Liquids ­Salty so they dissolve in water ­Sprayed on root zone or as a foliar application ­Have high tendency to ‘burn’ plants ­Are usually short-lived Granules ­Most common form ­Heavy pellets don’t drift too far ­Can be slow-release

Fertilizer Forms Tablets and Spikes ­Large compressed items that are pushed into the soil or placed in a hole ­Expensive for the amount of nutrient they contain ­Release nutrients very slowly over time Several months to more than a year

Purchase Many factors exist when choosing a fertilizer to purchase ­Slow or fast release ­Organic or inorganic ­Liquid or solid ­Analysis ­Price

Analysis Is a statement of the type and quantity of nutrients, and must be included on every package The standard statement form is 3 numbers separated by hyphens on the bag ­ for example The numbers give %N, %P as P 2 O 5, and %K as K 2 O

Analysis Fertilizers are also grouped based on relative amounts of N, P, and K Balanced = Complete = Single Element –

Application Methods Topdressing Pre-plant incorporation Sidedressing Needle Feeding Drilled-hole Foliar

Mineral Home Macronutrients Nitrogen will be needed by turf, flowers, shrubs, trees, and the garden, add yearly in early spring as roots start to grow For turf two applications - early spring and early fall Use residual acid form - ammonium sulfate

Mineral Home Macronutrients Phosphorus may be needed every years for turf, flowerbeds, shrubs, trees and gardens Potassium will generally not be needed. There is a sufficient supply in Utah soils and Utah waters are high in potassium

Mineral Home Secondary mineral nutrients are usually not needed ­Calcium Magnesium Sulfur

Mineral Home Micronutrients ­Iron ­Manganese ­Zinc Look for early signs of deficiencies Test with chelated materials applied to the foliage to determine needs