The Effects of Biological and Chemical Nitrogen Fertilizers and Iron Micronutrient on Forge Quality and Yield of Maize (Zea mays L.)

Improving forage yield and quality is a major concern for the producer. Sustainable crop production requires careful management of all nutrient sources in agroecosystems. Biological fertilizers, including Azospirilum, Azotobacter, Bacillus and Pseudomonas bacteria, can increase plant growth and yield through biological nitrogen fixation and increased solubility of macro elements such as phosphorus. Iron is the most important micro element for crops. Iron is required to perform many plant metabolism and growth activities. The experiment was conducted to investigate the effects of biological fertilizers combined with chemical fertilizers and iron micro element on yield and quality of maize (MV 500 cultivar) forage.

The experiment was conducted as a split plot based on randomized complete block design with three replications. The main plots consisted of different levels of urea fertilizer: Nitrokara biofertilizer, 150 kgha-1 urea + Nitrokara biofertilizer (Azorhizobium caulinodans), Super Nitro Plus biofertilizer (Azospirillum, Bacillus subtilis, Pseudomonas fluorescens), Super Nitro Plus biofertilizer + 150 kgha-1 urea without nitrogen fertilizer 450 kgha-1 urea, Nitrokara biofertilizer +300 kgha-1 urea, and Super Nitro Plus biofertilizer + 300 kgha-1 urea. The subplots consisted of two iron levels, including 10 kgha-1 iron chelate (Fe EDTA) and without iron application. The measured traits were crude protein, neutral detergent fiber, acid detergent fiber, ash, leaf to shoot ratio, ear to plant ratio and forage yield. Data were analyzed using MSTATC software.

Analysis of variance showed that the interaction effects of nitrogen fertilizer sources and iron levels were significant on crude protein, neutral detergent fiber, acid detergent fiber, ash, ear/plant ratio and forage yield. The highest crude protein and ash of maize forage were obtained from supernitroplus + 300 kgha-1 urea and iron application. Control treatment (without nitrogen and iron fertilizers) produced the most ADF and NDF values. The highest dry forage yield belonged to Super Nitro Plus + 300 kgha-1 urea with iron fertilizer and the lowest value obtained from control treatment without N and iron fertilizers.

The results of this study showed that the combined application of supernitroplus biofertilizer and urea fertilizer along with iron micro element increased maize forage quality and yield compared to the sole application of urea chemical fertilizer. Microorganisms constituting biofertilizers are very benefitial to the plant. They have the ability to enhance plant growth through increasing nutrient availability and uptake with minimal contribution to the environmental pollution, unlike the use of pure mineral fertilizers. The integration of biofertilizers and moderate mineral N fertilizer application accompanied with iron micro element is highly recommended in the production of maize forage.