GREENHOUSE EXPERIMENTS FOR EVALUATION OF THE METHODS OF DETERMINING POTASSIUM FERTILIZER NEEDS

The evaluation of the methods of potassium fertilizer needs was done in past years in several countries.
However, very little research on this subject was done in Poland.
The Egner-Riehm method is used for testing agricultural soils in this country, but it does not always show correctly potassium needs.
Many soils evaluated by this method as having a potassium deficiency, do not need potassium fertilizers.

For this reason, pot experiments were carried out at Skierniewice Experimental Field of Agricultural University in 1966–1968. Greenhouse tests with Italian ryegrass were made in 1966, using 22 different soils (Table 1). Plants were cut

Table 1. The plant yields dependent on potassium fertilization in pot experiments

Plants

Number of soils

The average dry weight of plants in g per pot

Yield increase in %

		control	0.5g K2O per pot
Italian ryegrass	22	15.7	23.1x	47
Barley spr.	41	13.6	19.8x	45
Rape	41	5.6	7.0x	25
Oat	40	15.8	19.8x	25
Buckwheat	40	4.1	4.9x	19

^x significant yield increase

four times a year.
In 1967 both barley and rope were grown on 41 different soils.
In 1968 the experiments with oat and buckwheat on 40 soils were carried out.
Altogether 103 soils

Symposium on Nutrition and Fertilization of Vegetables

S. Mercik

https://doi.org/10.17660/ActaHortic.1973.29.11