INFLUENCE OF TILLAGE ON SOIL PROPERTIES, YIELD, AND FAT AND PROTEIN CONTENT IN THE GRAIN OF MAIZE

Na pokušalištu Visokog gospodarskog učilišta u Križevcima tijekom 2008. godine istraživan je utjecaj različitih načina obrade na značajke tla i prinose zrna kukukuruza (Zea mays L.). Uz navedeno, istraživan je utjecaj obrade i značajki tla na ukupni sadržaj masti i bjelančevina u zrnu kukuruza. Uglavnom je utvrđen povoljniji utjecaj reducirane obrade na fizikalne značajke tla u odnosu na intenzivnije načine obrade s više zahvata. Kod svih istraživanih načina obrade tla ustanovljeni su pozitivni korelacijski odnosi između sadržaja ukupnih masti, bjelančevina i kapaciteta tla za vodu. Najveći korelacijski koeficijent utvrđen je za bjelančevine kod varijante B (r = 0,51; p < 0,05), a za ukupni sadržaj masti kod varijante E (r = 0,56; p < 0,05). Veće vrijednosti kapaciteta tla za zrak također su utjecale na veći sadržaj ukupnih masti (signifikantno kod varijante D s vrijednošću r = 0,65; p < 0,01) i bjelančevina (signifikantno kod varijante D s vrijednošću r = 0,63; p < 0,01). Utvrđen je također nepovoljan utjecaj zbijenosti tla na sadržaj ukupnih masti (signifikantno kod varijante D s vrijednošću r = - 0,77; p < 0,001) i bjelančevina (signifikantno kod varijante D s vrijednošću r = - 0,51; p < 0,05) kod svih istraživanih načina obrade tla. Signifikantno manje vrijednosti sadržaja humusa u tlu bile su kod varijante E (intenzivnija obrada) u odnosu na ostale istraživane načine obrade tla, osim u odnosu na varijantu B (p < 0,05), a glede ukupnog sadržaja dušika u tlu statistički opravdanih razlika nije bilo. Također su utvrđeni pozitivni korelacijski odnosi između sadržaja bjelančevina i količine humusa u tlu (signifikantno kod varijante B; r = 0,73; p 0,05). Slični korelacijski odnosi dobiveni su između sadržaja ukupnih masti u zrnu i ukupnog sadržaja dušika (p> 0,05). Većinom su utvrđeni negativni korelacijski odnosi između ostvarenih prinosa i sadržaja bjelančevina u zrnu, a također je dobiven najveći negativni korelacijski koeficijent između ukupnog sadržaja masti u zrnu i prinosa (p >0,05). Signifikantno niži prinosi zrna kukuruza bili su na varijanti A (reducirana obrada) u odnosu na ostale istraživane načine obrade tla (p < 0,05).The influence of different tillage systems on soil properties and yields of maize grain (Zea mays L.) was investigated during 2008 on the experimental field of the College of agriculture in Križevci. The influence of tillage and soil properties on total fat and protein content in maize grain was also investigated. Mainly more positive effect of reduced tillage on physical soil properties was determined compared to more intensive systems of tillage. Positive correlations between fat and protein content and water capacity of soil were determined for all investigated tillage systems. The highest correlation coefficient was determined for protein content in tillage system B (r = 0.51; p<0.05), and for total fat content in system E (r = 0.56; p < 0.05). The higher values of soil air capacity also influenced a higher total fats content (significant for tillage variant D with the value r = 0.65; p < 0.01) and also a higher protein content (significant for tillage variant D with the value r = 0.63; p < 0.01). A negative impact of soil compactness on total fat content was also determined (significant for D variant with the value r = -0.77; p < 0.001) and on protein content (significant for D variant with the value r = -0.51; p < 0.05) for almost all investigated tillage systems. Significantly lower values of humus content in the soil were registered for E variant (more intensive way of tillage) compared to other variants of tillage, except in relation to variant B (p < 0.05), while there were no significant differences between tillage systems related to total nitrogen content in the soil. Positive correlations were determined between protein content and amount of humus in the soil (significant for B variant; r = 0.73; p 0.05). Similar correlations were determined between fat and nitrogen in maize grain (p > 0.05). Mostly negative correlations weredetermined between yields gained and content proteins in maize grain, and the highest negative correlation coefficient was determined between total fat content in maize grain and yields of maize grain (p > 0.05). Significantly lower yields of maize grain were determined for variant A (reduced tillage) compared to other investigated variants of tillage (p < 0.05)

Soil tillage as influenced by climate change

A long-term field trial was set up in order to define the effects of autumn or spring primary tillage upon the physical characteristics and yields of spring row crops – maize and soybean. The objectives were to assess and recommend the most effective tillage method. In the first trial year, the year factor had a stronger influence on maize yields compared to the tillage factor. In the second trial year, however, the situation was quite contrasted. The tillage factor had a stronger impact on soybean yields compared to the year factor. The twoyear investigation period was only allowed to draw some preliminary conclusions. For this reason the research will be continued