Effects of fertilization and crop rotation on magnesium content in winter wheat

Abstract

Magnesium (Mg) is a highly important biogenic element for all living organisms. Insufficient Mg nutrition in humans increases risks from heart and blood vessels diseases and susceptibility to stress. A major source of Mg in human nutrition is food of plant origin, so the Mg content of plants most notably the cultivated ones, is very important from the point of view of a healthy diet. Grains of cereal crops have a relatively low Mg content. Nevertheless, cereal crops are a major provider of Mg to humans, since cereal-based products are a staple of the human diet. In view of all this we thought it would be interesting to investigate the effects of crop rotation and fertilization on Mg levels in winter wheat, as the levels of chemical elements are known to depend largely not only on species and genotype but on cultural practices and environmental factors as well. Samples for analysis were taken from eight long-term stationary field trials established in 1946/47 on a chernozem soil. The trials involve various crop rotations with and without NPK fertilizer application: two-field with and without fertilization; three-field with and without fertilization four-field with fertilization; 12-field with fertilization (maize as preceding crop for wheat); 12-field with fertilization (soybean as preceding crop for wheat); and wheat monoculture with fertilization. Our results have showed that the type of crop rotation and fertilization had no significant effect on wheat grain Mg content. The straw Mg content depended largely on fertilization but not crop rotation type, meaning that fertilizer application primarily affected Mg levels in vegetative organs of wheat plants. The differences in Mg content between straw and grain were higher in the non-fertilized than fertilized treatments. The grain and straw yields depended primarily on fertilization, but they were also influenced by crop rotation, which affected Mg removal from soil by yield. Our results have shown that fertilizer application on chernozem soils well supplied with available Mg has no effect on wheat grain Mg content, but that it significantly increases the removal of this element from soil via increased yield. In the long-term, this fact should not be overlooked if plants are to be provided with optimum Mg supply, especially in soils with lower levels of this element.

Magnezijum je veoma važan biogeni elemenat za sve žive organizme. U radu je ispitan uticaj različitih plodoreda i primene NPK mineralnih đubriva na sadržaj magnezijuma u ozimoj pšenici. Uzorci za analizu uzimani su sa stacioniranih poljskih ogleda postavljenih na zemljištu tipa černozema 1946/47. godine. Na osnovu dobivenih rezultata može se zaključiti da različiti plodoredi i đubrenje nisu značajno uticali na udeo magnezijuma u zrnu pšenice. Istovremeno se u slami udeo magnezijuma značajno povećao pod uticajem đubrenja. Iznošenje magnezijuma prinosom zavisilo je pre svega od visine prinosa zrna i slame. Od ukupno nakupljene količine magnezijuma približno polovina se nalazila u zrnu i polovina u slami, što znači da se zaoravanjem slame značajan deo usvojenog magnezijuma vraća u zemljište. Dobiveni rezultati pokazuju da je zemljište tipa černozema dobro obezbeđeno pristupačnim magnezijumom za biljke, stoga plododred i đubrenje NPK đubrivima ne utiče značajno na njegov udeo u zrnu pšenice.