Produktivnost kukuruza u održivom sistemu gajenja

Abstract

Održivi sistemi gajenja useva su alternativa intenzivnoj, industrijalizovanoj poljoprivredi u kojoj je dudgogodišnja primena pesticida ugrozila životnu sredinu. U održivim sistemima gajenja, prioritet je smanjiti upotrebu herbicida i đubriva i povećati efikasnost proizvodnje uz korišćenje postojećih resursa radi zaštite agroekosistema. U tom smislu, pokrovni usevi i sistemi obrade zemljišta mogu doprineti značajnom smanjenju zakorovljenosti kukuruza, održanju kvaliteta zemljišta uz ostvarenje visokog i kvalitetnog prinosa. Istraživanja su sprovedena u Institutu za kukuruz Zemun Polje, Beograd, sa ciljem da se utvrdi koliki je doprinos održivog sistema gajenja (sa pokrovnim usevima) u poređenju sa konvencionalnim/intenzivnim sistemom gajenja, plodnosti zemljišta i produktivnosti kukuruza. Ogled je postavljen 2020. godine i čine ga tri sistema gajenja kukuruza:- ekstenzivni sistem: posle žetve strnine (oz. pšenica), zemljište je ostalo neobrađeno, krajem leta je primenjen totalni herbicid radi suzbijanja izniklih korova, u proleće je direktnom setvom posejan kukuruz - intenzivni sistem: posle žetve strnine (oz. pšenica), strnište je plitko zaorano (ljuštenje strništa), kasnije su primenom totalnog herbicida suzbijeni iznikli korovi, u jesen je zemljište duboko uzorano a u proleće je obavljena predsetvena priprema zemljišta frezom i setva kukuruza -održivi sitem: posle žetve strnine (oz. pšenica), strnište je plitko zaorano (ljuštenje strništa) nakon čega su posejani ozimi pokrovni usevi – ozimi ovas, ozimi stočni kelj i ozimi stočni grašak; pokrovni usevi su u proleće pokošeni i kada je biomasa svela i delom se razgradila, direktnom setvom je posejan kukuruz.Setva visokorodnog hibrida kukuruza najnovije generacije, ZP5601 je obavljena 6. maja 2021. u gustini od 60 606 biljka po ha. U navedenim sistemima gajenja kukuruza analiziran je sadržaj ukupnog N i C, kao i odnos C:N iz uzoraka zemljišta uzetih pre setve kukuruza kao i prinos kukuruza, obračunat na 14% vlage u zrnu. Na početku vegetacione sezone 2021. godine, najveći sadržaj organskog C je imala varijanta sa konvencionalnim sistemom gajenja, najveći sadržaj ukupnog N je utvrđen takođe u ovoj i varijanti sa ekstenzivnim sistemom gajenja, dok su najpovoljniji odnos C:N imale varijante sa pokrovnim usevima od ozimog stočnog kelja i stočnog graška. Na kraju vegetacionog perioda u promenljivoj i, za kukuruz, nepovoljnoj 2021. godini, najveći prinos je imao ekstenzivni sistem gajenja (6,70 t ha-1) a nešto niži konvencionalni sistem (6,38 t ha-1) dok je od pokrovnih useva najproduktivnije bilo gajenje kukuruza nakon stočnog graška (5,61 t ha-1).Sistemi gajenja kukuruza, posebno kada se radi o proizvodnji za ljudsku ishranu, će ubuduće sve više težiti održivosti i upotrebi alternativnih mera kad je u pitanju upotreba pesticida.

Sustainable systems of crop cultivation are an alternative to intensive, industrialised agriculture in which a long-term application of pesticides has endangered the environment. The priority in these systems is to reduce the use of herbicides and fertilisers and to increase the production efficiency while using existing resources to protect agro-ecosystems. In this sense, cover crops and tillage systems can contribute to a significant reduction in maize weediness, maintenance of soil quality while achieving high and quality yields. Studies were conducted at the Maize Research Institute, Zemun Polje, Belgrade, with the aim to determine the contribution of the sustainable cultivation system (with cover crops) in comparison to the conventional/intensive cultivation system, soil fertility and maize productivity. The trial was set up in 2020 and encompassed three maize growing systems:- extensive system: after stubble (winter wheat) harvest, soil remained untilled and at the end of summer a total herbicide was applied to control emerged weeds, while in spring, maize was sown by direct sowing - intensive system: after stubble (winter wheat) harvest, stubble was shallowly ploughed (shallow ploughing), later the total herbicide was applied to suppress emerged weeds; in autumn, soil was deeply ploughed up, while seedbed preparation with a cultivator and maize sowing were done in spring -sustainable system: after stubble (winter wheat) harvest, stubble was shallowly ploughed (shallow ploughing) and then winter cover crops (winter oats, winter fodder kale and winter field pea) were sown; cover crops were mowed in spring and when biomass was wilted and partially decomposed, maize was sown by direct sowing. Sowing of a high-yielding maize hybrid of the latest generation, ZP5601, was performed on May 6, 2021 at the sowing density of 60,606 plants ha-1. In the stated maize cultivation systems, the contents of total N and C, as well as the C:N ratio were analysed in soil samples drawn prior to maize sowing and maize yield was calculated at 14% grain moisture. At the beginning of the 2021 growing season, the highest content of organic C was recorded in the variant with the conventional cultivation system, whereas the highest content of total N was also determined in this variant but with the extensive cultivation system; the most favourable the C:N ratio was established in variants with cover crops consisted of winter fodder kale and field pea. At the end of the 2021 growing season that was variable and unfavourable for maize, the highest yield (6.70 t ha-1) was recorded in the extensive cultivation system; a slightly lower yield (6.38 t ha-1) was achieved in the conventional system, while the most productive (5.61 t ha-1) in the cover crop system was maize cultivation after field pea. Maize cultivation systems, especially when it comes to the production for human consumption, will increasingly tend to sustainability and the use of alternative measures instead of the pesticide application.