This document discusses soil fertility and fertilizers. It defines a fertilizer as a material added to soil that supplies essential nutrients for plant growth. Fertilizers are important for building up nutrient levels in soil and replenishing nutrients lost through processes like leaching. The document also explains how soil pH influences the availability of different nutrients and lists the optimal pH range for many common plants. It notes the pH levels of Illinois soils and provides a table showing the amount of limestone needed to adjust soil pH depending on its type and desired pH level.

2. Soil Fertility and Fertilizers
By
Allah Dad Khan

3. Soil Fertility and Fertilizers
• What is a fertilizer?
– Definition - a material added to the garden
that supplies essential nutrients plants need
for vegetative and reproductive growth.
• Why are fertilizers important?
– Build-up - increasing the level of minerals
and OM in the soil.
– Maintenance - replenishing nutrients lost
through leaching, removal during plant
growth, and harvest

4. Fertilizers and pH
• Optimum soil pH is
plant species
dependent
– Most plants will grow
well at pH 6.2-6.8
– IL soils slightly acidic -
5.8-6.8
Slightly
Tolerant
(pH 6.5-6.8)
Moderately
Tolerant
(pH 5.5-6.8)
Very
Tolerant
(pH 5.0-6.8)
Asparagus
Beet
Broccoli
Cabbage
Bean
Carrot
Corn
Cucumber
Potato
Rhubarb
Sweet
Potato
Watermelon

5. Fertilizers and pH
• pH influences nutrient availability
– Determines nutrient form in soil
– How strongly nutrients are bound to soil particles
• Nutrients deficient in acid soils
– Ca, P, Mg, Mo
• Nutrients deficient in alkaline soils
– Cu, Fe, Mn

6. Nutrient availability by pH

7. Adjusting pH
• Lime replaces H+ ions with Ca2+ ions
• Amount applied depends on soil type and pH
change desired
Desired pH ∆ Sand Loam Silt Loam Clay Loam
4.5  6.5
5.5  6.5
6.0  6.5
----------------------Lbs/Acre of limestone------------------------
2200
1200
600
5800
3400
1800
7000
4000
2200
8400
4600
2400