The effect of increased nitrogen amounts on the yield of green biomass and hay of forage sorghum, Sudan grass and their interspecies hybrid

Abstract

The area of the western Balkans is characterised with semi-arid climate, i.e. with hot summers and the unfavourable rainfall distribution. Growing maize silage has become unsafe, due to the appearance of long summer droughts. Alternative forage plants, such as fodder sorghum and Sudan grass, are more accustomed to drought conditions than maize and have recently became more interesting for growing under rainfed conditions. Their biomass quality does not lag much behind maize biomass quality. Under a more favourable water regime they regenerate well after mowing and in years of use they can give two to three swaths. The following genotypes were studied in the trial set up in the experimental filed of the Faculty of Agriculture in Belgrade during 2007, 2008 and 2009: NS Džin (fodder sorghum), Zora (Sudanese grass) and their interspecies hybrid Siloking. The plant nutrition consisted of the following amounts of nitrogen: 105, 150 and 180 kg ha-1. Ammonium nitrate was introduced into the soil before sowing. In addition to these cultivars, a control group of plants was grown (60 kg N ha-1). The standard fodder sorghum growing practices were applied. Obtained results indicate that these genotypes have a high yield potential of the above-ground biomass. The biomass yield has significantly increased with additional amounts of nitrogen. The biomass yield was the highest during the year with the most favourable water regime. The growing amounts of nitrogen demonstrated a great influence on quality, as well as, on the nutritional value of the dry biomass. Nitrogen increased quality of the biomass twofold, through the increased percentile participation of leaves in total the above-ground biomass and greater synthesis of total proteins. .

U uslovima globalnog zagrevanja područje zapadnog Balkana sve više poprima karakter semiaridne klime sa vrlo toplim i suvim letima. Gajenje silažnog kukuruza, glavne krmne biljke, postaje nesigurno usled nepovoljnog rasporeda padavina u vreme najveće potrošnje vode. Sirkovi su tolerantniji na sušu od kukuruza i postaju interesantni kao krmne biljke, posebno sudanska trava, koja se dobro regeneriše i daje, zavisno od režima vlažnosti, više otkosa u godini korišćenja. U ogledu postavljenom na Oglednom polju Poljoprivrednog fakulteta Beograd tokom tri godine (2007, 2008. i 2009) predmet istraživanja bili su genotipovi NS džin (krmni sirak), zora (sudanska trava) i siloking (interspecijes hibrid sirka i sudanske trave). Ishrana biljaka izvedena je sa 105, 150 i 180 kg azota po ha u obliku amonijum-nitrata, koji je unešen u zemljište pre setve. Primenjena je standardna tehnologija proizvodnje za sirkove. Rezultati istraživanja pokazali su da sva tri genotipa imaju visok genetički potencijal rodnosti nadzemne biomase, koji se značajno povećavao sa rastućim količinama azota. Prinos nadzemne biomase bio je najveći u godini sa najboljim rasporedom padavina, što ukazuje da i sirkovi pozitivno reaguju na povoljniji vodni režim. Povećane količine azota značajno su uticale na kvalitet, odnosno hranljivu vrednost suve biomase. Azot je uticao na veći udeo listova u ukupnoj biomasi i sintezu proteina. .