TI The influence of winter cower crops on the dynamics of mineral nitrogen, yield and quality of silage corn

Savremena poljoprivredana proizvodnja mora da odgovori na sve veće zahteve u pogledu zaštite životne sredine, smanjenja troškova proizvodnje i rasta tražnje za visoko kvalitetnim i zdravstveno bezbednim proizvodima. U takvim uslovima, jedan od odgovora poljoprivrednih proizvođača na postavljene izazove je i gajenje ozimih međuuseva jer oni mogu pružiti različite ekološke i proizvodne prednosti u poljoprivrednoj proizvodnji. Zbog toga, cilj rada je ispitati koje biljne vrste se mogu gajiti kao ozimi međuusevi u našim agroekološkim uslovima, kakav je njihov uticaj na zemljište, kakve su prednosti njihove primene za stočnu hranu ili za zelenišno đubrenje i kakav im je uticaj na sledeći usev. Ogled je postavljen na tri lokaliteta po metodi slučajnog blok sistema u tri ponavljanja. Istraživanja su izvršena u dva proizvodna ciklusa, od oktobra 2011. godine, kada su posejani ozimi međuusevi, do septembra 2013. kada je pokošen kukuruz za silažu. Biljne vrste korišćene za ozime međuuseve su maljava grahorica (Vicia vilosa Roth., sorta NS-Sirmium), ozimi tritikale (x Triticosecale Wittm. ex A. Camus, sorta Odisej) i njihova smeša. Pored varijanti sa ozimim međuusevima u ogled su uključene i varijante sa đubrenjem mineralnim azotom prema N-min metodi do 120 kg/ha azota (N1) i do 160 kg/ha azota (N2), kao i kontrola. Ozimi međuusevi posejani u prvom bloku su korišćeni za krmu, dok su međuusevi posejani u drugom bloku zaorani. U zavisnosti od vremenskih uslova ispitivane biljne vrste i njihove smeše gajene kao ozimi međuusevi, mogu da ostvare visoke prinose. Njihovim zaoravanjem značajno se može popraviti sadržaj mineralnog azota u zemljištu i obezbediti značajno povećanje proizvodnje kabaste stočne hrane na gazdinstvima. Dinamika mineralnog azota u zemljištu visoko je zavisna od ozimih međuuseva i najniži sadržaj azota je posle njihove žetve. Od ispitivanih vrsta, najvišu količinu azota iznosi tritikale, zatim ozima krmna smeša, a najmanje ozima grahorica. Od setve do žetve silažnog kukuruza, sadržaj mineralnog azota u zemljištu se povećava na svim tretmanima. Sadržaj mineralnog azota na kraju vegetacije je viši na tretmanima gde je zelena masa međuuseva odneta sa parcele. Međutim, preostalakoličina azota (ARNS) posle žetve kukuruza statistički je značajno viša na tretmanima gde su zaorani ozimi međuusevi od tretmana gde su oni odneti sa parcele i kreće se u intervalu od 66 do 150 kg N ha-1, a najveća je posle ozime krmne smeše. Prinosi zelene mase kukuruza u naknadnoj setvi posle ozimih međuuseva niži su u odnosu na varijante sa đubrenjem i kontrolu i kreću se od 6,6 t ha-1 do 22 t ha-1, dok kvalitet silokrme zadovoljava energetski potencijal kao i sadržaj proteina i minerala za kvalitetnu ishranu stoke na gazdinstvima. Datum
A modern agricultural production must respond to increasing demands in terms of environmental protection, reduction of production costs and an increased demand for high quality, safe and healthy products. In such conditions, one of the responses of agricultural producers to the challenges posed is also cultivation of winter cover crops, because they can provide different advantages in agricultural production in terms of ecology and production. Therefore, the aim of the research is to examine which plant species can be cultivated as winter cover crops in our agroecological conditions, their impact on the soil, the benefits of their application as animal feed or green fertilizer, and the impact they have on the subsequent crop. The field experiment was conducted on three locations using the random block design with replications. The research was carried out in two production cycles, from October 2011, when the winter cover crops were sown, to September 2013, when corn was reaped for silage. Herbaceous species used for winter cover crops are hairy vetch (Vicia vilosa Roth., variety NS-Sirmium), winter triticale (x Triticosecale Wittm. Ex A. Camus, Odyssey variety) and their mixture. In addition to variants with winter cover crops, variants with fertilization with mineral nitrogen according to the N-min method up to 120 kg/ha of nitrogen (N1) and up to 160 kg/ha of nitrogen (N2), as well as a control, are included in the field experiment. Winter cover crops sown in the first block were used for fodder, while the winter cover crops sown in the second block were ploughed. Depending on weather conditions of the tested plant species and their mixture grown as winter cover crops, they can achieve high yields. Their ploughing can significantly improve the content of mineral nitrogen in soil and provide a significant increase in voluminous fodder production in farms. The dynamics of mineral nitrogen in soil is highly dependent on winter cover crops and the nitrogen content is the lowest after their harvest. Out of the tested species, the highest nitrogen uptake was by triticale, then winter forage mix and the smallest by winter vetch. In the period from sowing to harvest of silage corn, thecontent of mineral nitrogen in soil increases with all treatments. The content of mineral nitrogen at the end of the vegetation is higher with treatments where the green mass of the cover crops were taken away from the plot. However, the remaining quantity of nitrogen (ARNS) after corn harvest was, statistically speaking, significantly higher in treatments where winter cover crops were ploughed, from the treatment where they were taken away from the plot and ranges from 66 to 150 kg N ha-1; the largest nitrogen content was measured after winter forage mix. The green mass yields of corn in subsequent sowing after winter cover crops are lower compared to fertilized variants and the control and range from 6.6 t ha-1 to 22 t ha-1, while the quality of silage meets the energy potential, as well as the content of proteins and minerals for quality livestock feed on farms.