One of the main objectives of the LIFE Steppes of La Mancha project is to optimize fertilizing in cultivated lands in the SPAs where the project takes place. For this reason, we find it necessary to talk about the key agents in fertilization: the elements. You can read the introduction to the first entry of the series The Role of Elements in Our Plants to learn more about the topic.

We need to understand the differences between some simple but very important terms:

  • MACRO ELEMENT: Every plant in its vegetative cycle requires nutritional elements for a favorable development and good production.
    • Macro elements are considered essential elements, and are divided into primary (nitrogen, phosphorus, and potassium) and secondary (sulphur, calcium, and magnesium)
  • MICRO ELEMENT: also known as minor elements, we can mention: boron, zinc, copper, manganese, iron, molybdenum, etc.

In this entry, we will talk about potassium and sulphur.



Kalium. Modified from BXXXD / CC BY SA 3.0 (Wikipedia)

  • Activates more than 50 enzymes
  • Invigorates the plants and increases their resistance against diseases
  • Has a fundamental role in the regulation of osmotic processes
  • Is present in the synthesis of carbohydrates, ATP, proteins, and starch
  • Activates the formation and transfer of sugars
  • Necessary for the development of meristematic tissues
  • Regulates water absorption, stoma openings, and increases resistance to the cold
  • Improves the color, flavor consistency, and preservation of fruits
  • Reduced atmospheric nitrogen in the form of ammonia in the Rhizobium nodes in legumes

With Potassium deficiencies, the symptomatology is produced acropetally, the coloration of leaves becomes green-blue or bronze. The apices and borders become folded and curled to the necrosis of the leaf, the fruits remain small because their sugar content is low and of poor quality.

This deficiency can be caused due to the excess of N, P, Mg, or Ca, as well as with soils that are very acid, saline, clayey, or sandy, high organic matter, and excessive leaching.

The excess of potassium is not toxic but produces an inferior absorption of Ca and Mg, and the plant’s general consumption increases.



Sulfur on vulcano. Modified from Yure13 / CC BY 2.5 (Wikipedia)

  • Constituent of amino acids, proteins, coenzyme A, and B-group vitamins.
  • Constituent of sulfolipids and lopoic acids
  • Takes part in protein synthesis and in photosynthesis as a component of chloroplasts, but not of chlorophyll
  • Constituent of volatile, smelly substances
  • Fundamental component of the soil’s microfiber
  • Enzyme activator
  • Favors plants’ vegetative growth and the development of their roots
  • Stimulates seed formation
  • Promotes the installation of Rhizobium in legumes


Sulphur deficiencies show yellowing in the entire leaf, including the nerves, as one of the first symptoms, usually starting in the youngest leaves. The apex can become yellow and then curly. The deficiency can also decrease ripening uniformity and protein levels.

These deficiencies can stem from the excessive use of N, Fe, and Al, the excessive risks of leaching, as well as sandy soils with low quantity of organic matter.

The excess of sulphur limits plant growth and the dimensions of the leaves.


You can read the previous entry in this series about nitrogen and and phosphorus.

… shortly, we’ll discuss more elements!!!


Want to learn about other actions of the LIFE project? Visit Actions LIFE Steppes of La Mancha

Download the dissemination material of LIFE Steppes of La Mancha

Learn about the farmers who work in favor of steppe bird populations.