Nutrients, pH and Fertility Topic 2035 Anna Blight

Cation Exchange Capacity (CEC) A measure of nutrient holding capacity of soil Cation exchange takes place when the root makes contact with negatively charged clay or humus particle Root exchanges H+ ions for other cations which are absorbed by roots for nutrition

CEC The amount of these positively charged cations a soil can hold is described as the CEC Expressed in milliequivalents per 100 grams (meq/100g) of soil The larger this number, the more cations the soil can hold A clay soil will have a larger CEC than a sandy soil

Cations are + charged Think of the ‘t’ in cation and + Ca++ Mg+ H+ K+ NH4+ H+ easily hydrated to H20 when joined with OH- ion NH4+ (ammonium) adheres to clay or humus and resists leaching until converted to NO3- by micro-organisms

Anions are - Clay and humus have many negative charges NO3- is nitrate form of Nitrogen Most preferred form of plants Highly soluble and easily leached from soil because of negative charge

pH Measure of H+ concentration pH is logarithmic function, each number is 10 times greater than the number before Range between 1 to 14

pH The pH of water and fertilizer also important Influences nutrient availability Lots of plants like slightly acid soil of 6.5 to 6.8.

Low pH High H+ ACID soil pH below 7 If pH is too low, add lime

High pH Low H+ ALKALINE soil pH above 7 If pH is too high, add sulfur

Fertility Soil tests can determine pH and nutrient availability in the soil Fertilizer analysis is represented as a percentage by weight of elemental N, P2O5 and K2O fertilizer contains 10% nitrogen, 4.4% P and 8.3% K

Fertilizer analysis P2O5 is 44% actual elemental Phosphorus Multiply P205 x.44 to obtain P K2O is 83% actual elemental Potassium Multiply K2O x.83 to obtain K

CHOPKNSCaFeMg “See Hopkins Café, Mighty Good!” Carbon, Hydrogen, Oxygen, Phosphorus, Potassium, Nitrogen, Sulfur, Calcium, Iron and Magnesium

Macronutrients NPK Nitrogen, Phosphorus, Potassium Most important nutrients used in larger quantities by plants Secondary are Calcium, Magnesium, and Sulfur (Ca Mg S)

Micronutrients Used in smaller quantities by plants Iron, Copper, Zinc Manganese, Boron, Molybdenum Chlorine

Nitrogen Important for overall growth of plant Deficiency symptoms are small, pale yellow leaves Stunted growth

Phosphorus Growth and flower and root development Deficient plants show purple/red on the older leaves or dead areas on leaves

Potassium (K) Regulation of water within plant cell and water loss through transpiration Disease resistance Potassium deficiency shows mottled chlorosis in leaves, or dead areas on leaf tips and margins

Resources Integrated Plant Health Management Training Program for Landscape Maintenance Providers, MSU Nursery and Landscape Team TMhttp://hubcap.clemson.edu/~blpprt/bobweb/BOBWEB24.H TM