What is the characteristic of unavailable potassium?
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It cannot be easily accessed by plants.
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What is the characteristic of unavailable potassium?
It cannot be easily accessed by plants.
What is the role of primary mica in potassium release?
It releases potassium to vermiculite.
What is the atomic weight of potassium?
39.10.
What does 'required potassium' refer to?
The certain amount of potassium needed for optimum yield.
Which minerals primarily contain relatively unavailable forms of potassium?
Feldspar and micas.
What percentage of total soil potassium is readily available?
Only 1 - 2%.
What are the two main factors affecting available potassium?
Additions and losses.
What is a common consequence of liberal fertilizer applications in drainage water?
Considerable quantity of potassium.
Under what soil condition do leaching losses of potassium typically result in yield losses?
Very sandy soils.
Where is most potassium found in soils?
Most of the K is held or fixed rigidly as part of the primary minerals.
What happens to potassium content in plants when soil potassium is low?
The potassium content in plants tends to be low.
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.
What is the term for the removal of soluble potassium in soil?
Luxury consumption.
What does Figure 2 illustrate?
The general relationship between the potassium content of plants and the available soil potassium.
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.
What is the most common form of available potassium in soil?
Exchangeable form.
What are the three forms of potassium in soils?
Unavailable, readily available, and slowly available.
What defines readily available potassium?
It is easily accessible for plant uptake.
What is luxury consumption in relation to potassium?
It refers to the excessive uptake of potassium by some crops beyond their actual needs.
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.
What does Figure 3 illustrate regarding potassium?
The release of potassium from primary mica to vermiculite and the fixation of exchangeable potassium.
What happens to exchangeable potassium in the diagram?
It is fixed by reversing the release reactions.
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.
What is a common solution for maintaining potassium levels in soil?
Increased use of potassium fertilizers.
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.
How do primary minerals contribute to the potassium cycle?
They release potassium through weathering processes, making it available for plant uptake.
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.
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.
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.
What is the primary focus of the document?
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.
What role do primary minerals play in soil fertility?
They are essential for providing potassium, which is crucial for plant growth and development.
What percentage of potassium in mineral soils is relatively unavailable?
90 - 98%.
What factors can lead to potassium leaching losses?
Heavy rainfall and irrigation can cause potassium to leach away from the soil.
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.
Why is understanding potassium availability important?
It helps in managing soil fertility and crop production.
What is the estimated annual loss of potassium by leaching in humid regions with moderate fertilizer rates?
35 kg/ha.
What is slowly available potassium?
Potassium that is released gradually for plant use.
What regulates the availability of potassium to plants?
The fixation of potassium as part of primary minerals.
Which form of potassium is most readily absorbed by higher plants?
Potassium in soil solution.
What is the chemical symbol for potassium?
K.
What are important mineral sources of potassium?
Feldspar, muscovite, and biotite.
What is the total quantity of potassium typically found in mineral soils?
35,000 - 50,000 kg K/HFS.
Why are feldspar and micas considered relatively unavailable forms of potassium?
They are quite resistant to weathering.
What are the three forms of potassium in soil?
Non-exchangeable K, exchangeable K, and soil solution K.
What does Figure 4 illustrate?
The relationship between available potassium, additions, and losses.
What is the annual loss of potassium due to crop removal?
As great as 100 kg/ha.
Do leaching losses of potassium usually affect crop yields?
No, except on very sandy soils.
What potassium level is required for optimum growth in plants?
An adequate level of potassium that meets their growth needs.
What is the 7th most abundant element in the Earth's crust?
Potassium.
How much potassium is estimated to be removed by silage corn per hectare?
140 - 180 kg.
What are the advantages of frequent light applications of potassium?
They help mitigate luxury consumption by crops, reduce leaching losses, and minimize fixation.
What is luxury potassium consumption in plants?
When plants absorb more potassium than is required for optimum growth.
What minerals are involved in fixing potassium ions in the soil?
Vermiculite, smectite, and other 2:1 type minerals.
How does potassium removal compare to other essential elements?
Crop removal of potassium exceeds that of the other essential elements.
In which areas is potassium fertilizer usage particularly prominent?
In cash crop areas and regions with sandy soils.
What role do non-exchangeable potassium ions play in soil?
They act as an extremely important reservoir of slowly available nutrients.
