Effects of crop rotation and fertilization on readily available potassium content

Abstract

The objective of this study was to investigate effects of rotation and fertilization on readily available potassium in soil at long term experiment 'Plodoredi' at Rimski Šančevi, Novi Sad. The study treatments were: fertilized and unfertilized three-year crop rotation (wheat-maize-soybean), fertilized and unfertilized two-year crop rotation (wheat-maize). The unfertilized plots were established 1946/1947, while the fertilized one was set up in 1969/1970. Since 1986, on fertilized plots mineral fertilizers with phosphorus, potassium and manure were not applied because of a high P and K content. Nitrogen is used every year on fertilized plots at 120 kg ha-1 for maize and 100 kg ha-1 for wheat. The result suggests that long term application of fertilizers have major effect on potassium content in both years and soil layers. Differences among two-and tree-year rotation in available potassium content were statistically significant only in the 30-60 cm layer. Low content of potassium could contribute to lower yield formation, particularly in dry years, however our study showed that chernozem has high potential for potassium release from clay mineral. On the other hand as a result of the long-term fertilization considerable accumulation of potassium occurred at fertilized plots.

U radu su dati rezultati istraživanja uticaja plodoreda i đubrenja na sadržaj lakopristupačnog kalijum u zemljištu. Eksperimentalni rad je izveden na oglednim poljima Instituta za ratarstvo i povrtarstvo na višegodišnjem ogledu 'Plodoredi'. Višegodišnja primena đubriva imala je značajan uticaj na sadržaj lakopristupačnog kalijuma, dok razlike između dvopoljnih i tropoljnih rotacija nisu utvrđene. Sadržaj lakopristupačnog kalijuma na neđubrenim rotacijama se nalazi u nivou optimalne obezbeđenosti nakon 55 godina od njihovog zasnivanja, dok je njegov nivo na đubrenim parcelama značajno viši od optimalnog i nije potrebno njegovo unošenje đubrivima.