**Author details**

**Kar** - soil available K content required by the most sensitive crops in a fixed crop rotation,

It is possible, based on specific K requirements to assign all cultivated crops into a particular soil available K classes. This has been reported in Table 10 for key crops cultivated in Po‐ land. By using this operational scheme, the farmer can define a right place for crops grown in a particular crop sequence with respect to the required level of soil available K. This table can be considered as the first step in the development of the K fertilizing plan, oriented on K

high K sensitive crops vegetables, sugar beet, potatoes oil-seed raps, grain legumes

The modern nitrogen-oriented agriculture relies on mining of soil nutrient resources, mainly potassium. Therefore, its key attribute is low water- and nitrogen-use efficiency and high year-to-year variability of yields. Crop growth on soils poor in available potassium limits, consequently, food production in many regions of the world. Hence, the principal objectives of sustainable management of potassium are to: i) reduce year-to-year variability of harvest‐ ed yields, ii) increase water- and N- use efficiency, iii) decreasing the pressure of agriculture on local and global environment. All applied agronomic measures should take into account K requirements of the most sensitive crop in a fixed crop rotation. Next, the required range of available K for the most sensitive crop, in turn should ensure effective N use during key stages of yield performance by all growing crops. The main way of fulfilling these goals is to gradually build-up or to re-build the attainable soil K pool. There are three key methods of economically profitable and environmentally sound K management. All of them rely on

**Soil agronomic category Very light Light Medium Heavy**

mg K2O kg-1 soil, the critical range

the Egner-Riehm K extraction method

**7. Conclusion**

Legend : low K sensitive crops: rye, oats, triticale

medium K sensitive crops:: wheat, barley, maize

**Figure 10** Critical ranges of available potassium1 for key crops in Poland

**Potassium rating**

Very low Low Medium High Very high

164 Soil Fertility

**Kca** - current level of soil available K, mg K2O kg-1 soil

3 - coefficient for converting soil K into K rates.

**Krec** - K recycled in plant residues and/manure, kg K2O ha-1

requirements of the most sensitive crop in the given crop sequence.

Witold Grzebisz, Witold Szczepaniak, Jarosław Potarzycki and Remigiusz Łukowiak

Department of Agricultural Chemistry and Environmental Biogeochemistry, Poznan University of Life Sciences, Poland
