Review  Physical properties of soils??

Review  Physical properties of soils?? Soil texture Soil structure Density

Review  Chemical properties of soils??

Review  Chemical properties of soils?? pH CEC

Review  Chemical properties of soils?? pH CEC  What is the pH of agricultural soils?

Review  Chemical properties of soils?? pH CEC  What is the pH of agricultural soils? between 6 and 7

Review  Chemical properties of soils?? pH CEC  What is the pH of agricultural soils? between 6 and 7  Why is this range the optimum condition?

Plant Nutition

Introduction How many elements do we find in plants? Do plants need all the elements in the same amount? How does agriculture effect the soil nutrients?  What is the solution?

Introduction 60 or more elements are found in plants.  17 essential

Introduction 60 or more elements are found in plants.  17 essential Macronutrients Micronutrients  Enzyme cofactors

Macronutrients

Introduction 60 or more elements are found in plants.  17 essential Macronutrients Micronutrients  Enzyme cofactors

Micronutrients

60 or more elements are found in plants.  17 essential Macronutrients Micronutrients  Enzyme cofactors What is the relationship between plant nutrition deficiency and humans or animals?  China example

Nitrogen  Nitrogen role in plants Protein Base pairs for RNA/DNA Chlorophyll Hormones (ABA, cytokinins)

Nitrogen  Nitrogen role in plants Protein Base pairs for RNA/DNA Chlorophyll Hormones (ABA, cytokinins)

Nitrogen  Nitrogen role in plants Protein Base pairs for RNA/DNA Chlorophyll Hormones (ABA, cytokinins)  2% of DW  Which type of transport requires ATP?

Nitrogen deficiency  Poor, stunted growth with pale leaves and weak stems.  Leaves often turn orange or red, may fall prematurely. Fruit trees Vegetables

Phosphorus ATP/ADP DNA/RNA Phospholipids Membrane Phosphoproteins 10% of N

Phosphorus Deficiency Poor growth Fruits are small and acid tasting Leaves become brown or red if P is severely deficient. Corn and grassy plants Oldest leaves are affected first

Potassium  Cofactor in osmosis  Stomata control  Protein synthesis  Deficiencies: Dull and spare flowers Low fruit yield and poor quality. Tissues become soft and susceptible to attack from pests. Brown scorching and curling of leaf tips, and yellowing of leaf veins. Purple spots may also appear on the leaf undersides.

Iron  Enzyme activator  Required for chlorophyll synthesis  When soils are alkaline, iron may become unavailable.  Applications of an acid nutrient formula can help.

Zinc  Energy production  Protein synthesis  Formation of chlorophyll  Growth regulation  Deficiency Symptoms: Delayed maturity Symptoms occur mainly in new growth Short internodes Decrease in leaf size

Soil, Water and Minerals Silicates (SiO 4 -4 )  93% of earths crust Rings of water form around soil particles. Soil solution Cations and Anions dissolve in water. 50% of soil vol.

Soil, Water and Minerals What are some factors in ion binding to soil particles? Charge ( + & - ) Size Concentration

Soil, Water and Minerals Ca 2+ vs. Na + High conc. of Na + vs. Low conc. of Ca 2+

Soil, Water and Minerals Why is it important to know these rules? Salty soils – high levels of Na + Useful ions end up in ground water Southwestern US

Acidic Soils Acidic soils are nutrient poor.  Where do we find acidic soils?  Why?

Acidic Soils Acidic soils are nutrient poor.  Where do we find acidic soils?  Why? CO 2 + H 2 O ↔ H 2 CO 3 ↔ H + + HCO 3- H + displaces other cations. Acidic soils bring toxic ions into the soil solution  Aluminum ions

Cation Exchange CO 2 released from roots (indirect H + ) H + can also be secreted (direct) H + then replaces the mineral cations in soil Minerals are released Roots uptake the minerals

Nitrogen Why is Nitrogen important for plants?

Nitrogen Why is Nitrogen important for plants? Proteins, DNA, RNA, chlorophyll, and hormones

Nitrogen Why is Nitrogen important for plants? Proteins, DNA, RNA, chlorophyll, and hormones Do you remember the symptoms of nitrogen deficiency?

Nitrogen Why is Nitrogen important for plants? Proteins, DNA, RNA, chlorophyll, and hormones Do you remember the symptoms of nitrogen deficiency? Poor growth Weak stems Discoloration of leaves

Nitrogen and Bacteria N 2 can not be used directly by plants NO 3 - or NH 4 + Nitrogen fixation –Soil bacterial - Rhizobium –The conversion of N 2 into NO 3 - or NH 4 + Legumes are rotated with other crops to enrich the soil.

Nitrogen Fixation by Bacteria

Review Macro and Micronutrients –Importance to plants –Deficiency symptoms Ion and soil particle interactions Cation exchange Nitrogen fixation