Chemical composition and yield of maize green biomass as affected by bacterial and mineral fertilization

The purpose of the study was to evaluate the influence of an application of different rates of composite mineral fertilizers and their combination with bacterial inoculants (N-fixing Klebsiella planticola and Enterobacter spp.) on chemical composition and yield of the maize green biomass (without spikes) on acid Eutric Cambisol during the two growing seasons: 2006 and 2008. Unfertilized soil was used as a control. The contents of nitrogen, phosphorus, potassium and crude proteins in biomass samples were determined three times during the maize vegetation season, as follows: stage of intensive growth, milk-waxy maturity stage and full maturity stage. Measuring of the green biomass yield was carried out at the end of the vegetation. The results of the study showed that the use of high rates of composite mineral fertilizers and their combination with bacterial inoculants resulted in increased contents of nitrogen, phosphorus, potassium and crude proteins in the maize biomass during the both study years, which was noticeably observed in the stage of intensive growth. The highest increase in the biomass yield was obtained by the same mentioned treatments, although the combination of bacterial inoculants and lower rates of mineral fertilizers resulted in higher yields comparing to the application of lower rates of the pure mineral nutrients. The data suggest that the studied bacterial inoculants can be used in further investigations as the potential agents of new biofertilizers for improved maize production and other agriculture crops in animal nutrition. Cilj ovog istraživanja je bio da se proceni uticaj primene različitih doza kompleksnih mineralnih đubriva i njihovih kombinacija sa bakterijskim inokulantima (azotofiksirajuće bakterije Klebsiella planticola i Enterobacter spp.) na hemijski sastav i prinos zelene biomase kukuruza na kiselom eutričnom kambisolu tokom dve vegetacione sezone: 2006 i 2008. Neđubreno zemljište je služilo kao kontrola. Sadržaj azota, fosfora, kalijuma i sirovih proteina u uzorcima biomase su određivani tri puta tokom vegetativne sezone kukuruze, i to: u fazi intenzivnog porasta, fazi mlečno-voštane zrelosti i fazi pune zrelosti. Merenje prinosa zelene biomase obavljeno je krajem vegetacije. Rezultati istraživanja su pokazali da je primena visokih doza kompleksnih mineralnih đubriva i njihova kombinacija sa bakterijskim inokulantima uticala na povećanje sadržaja azota, fosfora, kalijuma i sirovih proteina u biomasi kukuruza tokom obe godine istraživanja, što je naročito izraženo u fazi njegovog intenzivnog porasta. Najveći porast prinosa biomase je dobijen na istim navedenim varijantama, a isto tako je i primena kombinacije bakterijskih inokulanata i manjih doza mineralnih đubriva rezultirala većim prinosima u odnosu na primenu manjih doza čistih mineralnih hraniva. Dobijeni podaci ukazuju da se ispitivani bakterijski inokulanti mogu koristiti u daljim istraživanjima kao potencijalni agenti novih biofertilizatora u cilju poboljšanja proizvodnje kukuruza i drugih poljoprivrednih kultura u ishrani životinja.