Fertility Check Corner: Potassium (K)
Elements are essential for plant growth. Chemical elements are obtained from the air and water, unlike nutrient elements found in the soil. Nutrient element Potassium (K) is an essential major nutrient for crop production. Classified as a macronutrient, Potassium is absorbed in large amounts by most plants through root uptake.
Of all the essential elements, potassium is the third most likely, after nitrogen and phosphorous, to limit plant productivity. In soil, potassium is present as K+, enabling potassium to be held tightly within the soil matrix, limiting offsite movement. Potassium is found naturally in many soils. However, highly weathered soils usually contain lower levels.
Potassium absorbed by plants is used to control or regulate cellular enzymes responsible for energy metabolism, starch synthesis, nitrate reduction, photosynthesis and sugar degradation. Potassium plays a major role in a plant’s ability to withstand drought conditions, provide better resistance to certain fungal diseases and increase tolerance to insect pressure. It also helps plants adapt to environmental stresses.
Potassium deficiency is easily detected compared to other nutrient deficiencies. Potassium is mobile within plants, therefore when deficiency occurs it is seen first in the older leaves. The tips and edges of the oldest leaves begin to turn yellow and eventually brown.
Plant tissue analyses can determine the combined soil and crop nutrient element status. When testing for Potassium, adequate levels should fall within 1% to 4% in most plants. In acidic soils, Potassium can be lost through leaching because other minerals such as Aluminum are held tightly by the soil complex and can negatively affect plant growth. By applying lime, exchange sites for holding Potassium open up and leaching losses are reduced.
Routine soil testing on your field will provide you with the best information to make decisions about Potassium fertilization. Contact your local SGS Soil Laboratory or sales representative today to request soil sampling or testing or find out more information.
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