p.8
Forms of Potassium in Soils
What is the characteristic of unavailable potassium?
It cannot be easily accessed by plants.
p.12
Potassium Cycle and Availability
What is the role of primary mica in potassium release?
It releases potassium to vermiculite.
p.6
Crop Removal of Potassium
What does 'required potassium' refer to?
The certain amount of potassium needed for optimum yield.
p.5
Leaching Losses of Potassium
What is a common consequence of liberal fertilizer applications in drainage water?
Considerable quantity of potassium.
p.4
Forms of Potassium in Soils
Where is most potassium found in soils?
Most of the K is held or fixed rigidly as part of the primary minerals.
p.7
Potassium Cycle and Availability
What happens to potassium content in plants when soil potassium is low?
The potassium content in plants tends to be low.
p.3
Potassium Cycle and Availability
What are primary minerals in the context of the potassium cycle?
Primary minerals are the original sources of potassium in soils, such as feldspar and mica.
p.7
Potassium Cycle and Availability
What does Figure 2 illustrate?
The general relationship between the potassium content of plants and the available soil potassium.
p.7
Potassium Cycle and Availability
What is the relationship between potassium content in plants and soil potassium availability?
High potassium content in plants corresponds to high available potassium in soil.
p.8
Forms of Potassium in Soils
What are the three forms of potassium in soils?
Unavailable, readily available, and slowly available.
p.8
Forms of Potassium in Soils
What defines readily available potassium?
It is easily accessible for plant uptake.
p.13
Frequency of Potassium Application
What is luxury consumption in relation to potassium?
It refers to the excessive uptake of potassium by some crops beyond their actual needs.
p.9
Forms of Potassium in Soils
What enhances the release of potassium from relatively unavailable minerals?
The solvent action of carbonic acid, stronger organic and inorganic acids, and the presence of acid clay and humus.
p.12
Potassium Cycle and Availability
What does Figure 3 illustrate regarding potassium?
The release of potassium from primary mica to vermiculite and the fixation of exchangeable potassium.
p.12
Potassium Cycle and Availability
What happens to exchangeable potassium in the diagram?
It is fixed by reversing the release reactions.
p.4
Potassium Cycle and Availability
How does the availability of potassium compare to phosphorus in mineral soils?
Potassium is found in comparatively high levels in most mineral soils, except sandy soils.
p.14
Increased Use of Potassium Fertilizers
What is a common solution for maintaining potassium levels in soil?
Increased use of potassium fertilizers.
p.13
Potassium Cycle and Availability
What is fixation in the context of potassium?
Fixation refers to the process where potassium becomes unavailable to plants due to binding with soil particles.
p.3
Potassium Cycle and Availability
How do primary minerals contribute to the potassium cycle?
They release potassium through weathering processes, making it available for plant uptake.
p.3
Potassium Cycle and Availability
Can potassium from primary minerals be directly utilized by plants?
No, it must first be weathered and converted into a form that plants can absorb.
p.13
Potassium-Supplying Power of Soils
Why might the idea of returning every kilogram of potassium removed by plants not always be correct?
Because moderately available forms of potassium in most soils can be utilized.
p.10
Forms of Potassium in Soils
In what two forms does available potassium exist in soils?
(a) In the soil solution (b) As exchangeable potassium adsorbed on the soil colloidal surfaces.
p.6
Crop Removal of Potassium
How does potassium removal by crops compare to phosphorus and nitrogen?
Potassium removal is high, often three to four times that of phosphorus and equal to that of nitrogen.
p.3
Potassium Cycle and Availability
What role do primary minerals play in soil fertility?
They are essential for providing potassium, which is crucial for plant growth and development.
p.13
Leaching Losses of Potassium
What factors can lead to potassium leaching losses?
Heavy rainfall and irrigation can cause potassium to leach away from the soil.
p.11
Readily Available vs. Unavailable Potassium
How do the rates of availability differ between non-exchangeable and exchangeable potassium?
Non-exchangeable K is slowly available, while exchangeable K is rapidly available.
p.15
Potassium Cycle and Availability
Why is understanding potassium availability important?
It helps in managing soil fertility and crop production.
p.8
Forms of Potassium in Soils
What is slowly available potassium?
Potassium that is released gradually for plant use.
p.4
Readily Available vs. Unavailable Potassium
What regulates the availability of potassium to plants?
The fixation of potassium as part of primary minerals.
p.10
Readily Available vs. Unavailable Potassium
Which form of potassium is most readily absorbed by higher plants?
Potassium in soil solution.
p.2
Importance of Potassium in Soil
What are important mineral sources of potassium?
Feldspar, muscovite, and biotite.
p.4
Potassium-Supplying Power of Soils
What is the total quantity of potassium typically found in mineral soils?
35,000 - 50,000 kg K/HFS.
p.9
Forms of Potassium in Soils
Why are feldspar and micas considered relatively unavailable forms of potassium?
They are quite resistant to weathering.
p.11
Forms of Potassium in Soils
What are the three forms of potassium in soil?
Non-exchangeable K, exchangeable K, and soil solution K.
p.15
Potassium Cycle and Availability
What does Figure 4 illustrate?
The relationship between available potassium, additions, and losses.
p.5
Leaching Losses of Potassium
Do leaching losses of potassium usually affect crop yields?
No, except on very sandy soils.
p.7
Potassium-Supplying Power of Soils
What potassium level is required for optimum growth in plants?
An adequate level of potassium that meets their growth needs.
p.13
Frequency of Potassium Application
What are the advantages of frequent light applications of potassium?
They help mitigate luxury consumption by crops, reduce leaching losses, and minimize fixation.
p.7
Crop Removal of Potassium
What is luxury potassium consumption in plants?
When plants absorb more potassium than is required for optimum growth.
p.11
Slowly Available Potassium and Soil Colloids
What minerals are involved in fixing potassium ions in the soil?
Vermiculite, smectite, and other 2:1 type minerals.
p.14
Crop Removal of Potassium
How does potassium removal compare to other essential elements?
Crop removal of potassium exceeds that of the other essential elements.
p.14
Increased Use of Potassium Fertilizers
In which areas is potassium fertilizer usage particularly prominent?
In cash crop areas and regions with sandy soils.
p.11
Slowly Available Potassium and Soil Colloids
What role do non-exchangeable potassium ions play in soil?
They act as an extremely important reservoir of slowly available nutrients.
