Plant Nutrition: Secondary and Micronutrients

1
Plant NutritionSecondary and Micronutrients
2
First requirements 1) water, 2) heat, and 3)
oxygen
3
Basic Concepts of Soil Fertility

• 16 essential elements for plant growth
• CHO
• Macro / secondary nutrients
• N, P, K, - Ca, Mg, S
• Micronutrients
• Cl, Mn, Fe, Mo, Zn, B, and Cu
• Forms available to plants

4
Plant Nutrient Composition
5
Forms available to Plants

• Ions are charged molecules
• Most plant nutrients are ions ( / -)
• Cations - positively charged ions (Ca)
• Anions - negatively charged ions (NO3-)
• Uncharged molecules (H3BO3)

6
How Plants Absorb Nutrients

• Through leaves (foliar) or through soil
• High nutrient demand - soil
• active uptake of specific nutrients
• Micronutrients can be foliarly applied
• mechanism is primarily diffusion
• good quick fix methods in greenhouses etc.
• Most soil nutrients enter through roots

7
Secondary Nutrient Form
8
Secondary Nutrient Mobility

• Calcium Most immobile nutrient in plants
• deficiency seen in newest tissue
• Magnesium somewhat mobile in plants
• deficiency in newer plant parts
• Sulphur mobile in plants
• less redistribution than N - overall chlorosis

9
(No Transcript)
10
Roles in Plant Nutrition

• N, P, and K covered in detail
• Calcium
• membrane integrity - blossom end rot
• Magnesium
• role in photosynthesis - interveinal chlorosis
• Sulphur
• role in amino acids - flavor - general yellowing

11
(No Transcript)
12
Magnesium Deficiency Interveinal chlorosis
13
Supplemented to Plants

• Secondary nutrient sources
• Ca, Mg - lime applications
• S - some P fertilizer forms
• Manure - some S
• Acid rain - some S

14
Micronutrient Form Function
15
Micronutrient Form Function
16
Micronutrients in Plant Nutrition

• Perform enzymatic functions in plants
• Zn, Mn, Cu, Fe - photosynthesis
• B - sugar formation translocation
• Mo - nitrate reductase (legumes)
• Cl - ionic buffer in plants

17
Soil pH Effect on Nutrient availability
18
Micronutrient deficiency symptoms harder to find
19
Zinc Deficiency
Broad white stripe on both sides of midrib
20
(No Transcript)
21
Micronutrient Mobility

• Iron Not mobile in plants
• Copper not mobile in plants
• Manganese not mobile in plants
• Boron, Zinc, and Molybdenum - not mobile
• Where do you expect to see deficiency?

22
(No Transcript)
23
Supplemented to Plants

• Micronutrients
• Chelated forms
• cationic micronutrients
• Frits (molten glass formulations
• cheaper - all but chloride
• Starter fertilizer
• Foliar application in cases of deficiency

24
Micronutrient Availability

• pH effect
• increased availability with low pH
• Exception to the rule Mo
• Micronutrient toxicity - reduced by liming

25

Mottled Leaves Seen on youngest foliage
26
Plants show bright yellow-green interveinal
chlorotic mottling
Most likely to see deficiency In high or low pH
soil ?