Optimization of nitrogen crop fertilization in sustainable agriculture practices | Optimizacija gnojidbe usjeva dušikom u održivoj poljoprivrednoj proizvodnji

English. Sustainable agriculture is based on the principles of adaptation of agroecosystem to a particular area habitat factors and the optimal utilization of biological-physical-chemical resources. Optimal agrotechnical procedures are carried out by measures of good agricultural practice that will ensure stable yields without harmful effect on nature and the environment. The aim of this paper was to determine the optimum, profitable and environmentally acceptable nitrogen dose for the three most common crops in eastern Croatia: maize, wheat and soybean and to track and measure level of ground water and concentration of NO3- i NH4+. The concentration of nitrate nitrogen in the groundwater at the locations of Šljivoševci and Ćelije ranged from 16 to 34 mg NO3- dm-3 and concentration of NH4+ from 3,2 to 9,3 mg NH4+ dm-3. The highest yield, plant population density and the largest crop residue mass of winter wheat were achieved on treatment with 170 kg N ha-1, while the lowest yields, plant population density and the crop residue mass were recorded on control and on treatment with manure. The highest yields and largest mass of soybean crop residue were measured at the location of Šljivoševci on treatment with 50 kg N ha-1, while the lowest yields were measured on the control. The highest yields of maize were measured in Šljivoševci location on treatment with 170 kg N ha-1 and the lowest on control. The fertilization treatment did not have any effect on crop residue mass and the largest plant population density was measured on treatment with 150 kg N ha-1 at the Šljivoševci location. The obtained results point the great importance of knowing the dynamics and availability of nutrients in soil, especially nitrogen, and to apply fertilizers in accordance with biological, economic and ecological conditions. The yield level should be observed through the profitability of production and also at the same time take into account the preservation of soil quality, prevention of degradation and protection of the environment.

Croatian. Održiva poljoprivreda temelji se na načelima prilagodbe agroekosustava stanišnim čimbenicima nekog područja i optimalnom korištenju biološko-fizikalno-kemijskih resursa. Mjerama dobre poljoprivredne prakse provode se optimalni agrotehnički zahvati koji osiguravaju stabilne prinose bez štetnog djelovanja na okoliš. Cilj ovog rada bio je utvrditi optimalnu, profitabilnu i ekološki prihvatljivu gnojidbu dušikom za tri najzastupljenija usjeva istočne Hrvatske: kukuruz, pšenicu i soju uz praćenje razine podzemne vode i koncentracije NO3- i NH4+. Koncentracija nitratnog dušika u podzemnoj vodi na lokalitetima Šljivoševci i Ćelije kretala se od 16 mg NO3- dm-3 do 34 mg NO3- dm-3, a NH4+ od 3,2 do 9,3 mg NH4+ dm-3. Najveći prinos, najgušći sklop i najveća masa žetvenih ostataka pšenice ostvareni su na tretmanu sa 170 kg N ha-1, dok su najmanji prinos, najrjeđi sklop i najmanja masa žetvenih ostataka zabilježeni na kontroli i na tretmanu gnojidbe stajskim gnojem. Najveći prinosi i najveća masa žetvenih ostataka soje ostvareni su na lokalitetu Šljivoševci pri gnojidbi od 50 kg N ha-1, dok su najmanji prinosi izmjereni na kontroli. Najveći prinosi kukuruza izmjereni su u Šljivoševcima na tretmanu s 170 kg N ha-1, a najmanji na kontroli. Masa žetvenih ostataka nije bila pod utjecajem gnojidbe, a najveći sklop je izmjeren na tretmanu sa 150 kg N ha-1 na lokalitetu Šljivoševci. Dobiveni rezultati ukazuju na važnost dobrog poznavanja dinamike i raspoloživosti hraniva, posebice dušika i primjenjivanja gnojiva u skladu s biološkim, ekonomskim i ekološkim uvjetima. Visinu prinosa potrebno je promatrati kroz profitabilnost proizvodnje istovremeno vodeći računa o očuvanju plodnosti tla, sprječavanju njegove degradacije i zaštiti okoliša.