Fattori che influenzano la risposta alla fertilizzazione potassica: una meta-analisi

Nitrogen (N), phosphorous (P) and potassium (K) are the most limiting factors in crop production. Potassium is a fundamental regulator of many plant physiological processes and, therefore, is central in the regulation of plant morphology and physiology. Indeed, it supports the vegetative development and the production of biomass, but it is also essential in reference to the reproductive stage, as it stabilizes the yields, contributes to the accumulation of reserve substances, improves the quality of the productions and also improves the nitrogen and phosphorus use efficiency. Furthermore, it also plays a particularly important role in resistance to biotic and abiotic adversities. Among the most important nutritional elements that plants can obtain from the soil, potassium is the most abundant and represents the seventh most abundant element of the earth's crust and on average the potassium reserves in the soil are copious, but it must be considered that a large part of this potassium is not available for plants. In the soil, this element is mainly found in primary and secondary minerals. The four fractions of potassium in order of availability are: soluble potassium > exchangeable potassium > fixed potassium > mineral potassium. Therefore, it is clearly necessary to distinguish fixed and non-exchangeable potassium (or, at least, not immediately available) from that which, on the other hand, is readily available. The proportion between the amount of the different reserves and between the forms of potassium present in the soil is the basis of availability for crops. Modern intensive production systems are often associated with unbalanced or insufficient potassium fertilization. If we don’t adequately manage this feature, potassium deficiency represents one of the most important limiting factors in agricultural production. Cereals (especially if we consider the most productive varieties) normally remove large amounts of potassium from the soil and intensive agriculture, if not supported by adequate application of fertilizers, can reduce soil fertility. This work focused on the role of potassium, as a fundamental element for the protection of soil fertility and as an essential macronutrient for plant development and yield, and also investigated the effect that pedoclimatic parameters have on the availability of potassium in the soil. and on removals by vegetables. Specifically, the focus was placed on wheat, corn and rice, as they not only represent (especially rice and wheat) three of the most widespread crops worldwide, but are also globally the basis of human population nutrition, as well as central also in the livestock sector.