Potassium in agriculture – Status and perspectives

Flashcards about Potassium in agriculture

What are major challenges for agriculture related to crop production?

Enhance crop yields in resource-efficient systems and stabilize yield formation under stress.

What percentage of the Earth's crust is made up of potassium?

About 2.1–2.3% of the earth’s crust.

What types of soils are inherently low in K availability?

Sandy, waterlogged, saline, or acidic soils.

What may result in a significant depletion of available soil K reserves?

Lower fertilizer K application in the context of unbalanced fertilization.

What are the four groups K in soil are classified into based on availability to plants ?

Water-soluble, exchangeable, non-exchangeable, and structural forms.

What primarily comprises the structural form of K in soil?

K-bearing primary minerals such as muscovite, biotite, and feldspars.

How do potassium-solubilizing bacteria release K from K-bearing minerals?

Organic acids that dissolve rock K or chelate silicon ions.

What are the major organic compounds released as root exudates that mobilize non-exchangeable K?

Organic acids such as citric, oxalic, tartaric, and malic acids, as well as amino acids.

What is involved in potassium fixation in the soil?

Adsorption of K ions onto sites in the interlayers of weathered sheet silicates.

What is the impact of mineral K fertilizers application on soil physical properties?

Enhances the water-holding capacity of soils and improves the structural stability of sandy soil.

What is used to extract the soil in simple soil extraction methods for measuring exchangeable K?

Neutral ammonium acetate, ammonium chloride, calcium chloride, or ammonium fluoride (Mehlich 3).

What is the major form of K fertilizer that is used nowadays?

Potassium chloride (KCl).

Which countries use almost 40% of the global K fertilizers?

China and the USA.

What is the typical range of critical K concentrations in dry matter for many crops?

0.5 to 2% in dry matter.

What is the likely cause of accumulation of sugars often observed in K-deficient leaves?

Impaired sucrose export from leaves, rather than a limitation of photosynthesis.

What direction is K transport in the phloem largely directed?

Older to younger plant tissues.

What are the early visible symptoms of K deficiency?

Chloroses at the tip of the oldest leaves.

Of what is the nutritional quality of plant products composed?

Appearance, nutritional, sensory, shelf life, and technological quality.

In most monocotyledonous plants, what is the most critical factor with ionic stress due to salinity?

Na load.

What is advisable to prepare existing cultivars for periods of drought stress?

K fertilization above the level required for optimum yield.