Agronomic Responses of Soybean Genotypes to Starter Nitrogen Fertilizer Rate

Abstract

The main nitrogen (N) sources in soybean production originate from soil fixing bacteria Bradyrhizobium spp. and from mineralization of soil organic N. These sources of N are often not sufficient to cover the N needs of the soybean. The present two-year field study aimed to evaluate the effects of soybean genotypes (Valjevka and Galina) and rates of starter fertilizer N (0, 30, 60, and 90 kg ha −1 ) on quantitative and qualitative parameters and on rain use efficiency (RUE) under contrasting weather conditions in the Pannonian region of Serbia. A field study conducted during two different growing seasons: first year with unfavorable weather conditions and second year with favorable weather conditions. As expected, the quantitative parameters, oil content, and RUE were higher in the year with favorable growing season, the second one. According to measured parameters, the genotype Valjevka performed higher yield potential as compared to the genotype Galina. The highest values of quantitative parameters and RUE were recorded at 60 kg N ha −1 , protein content at 90 kg N ha −1 and oil content 0 kg N ha −1 (control). This study suggests that proper genotype selection and application of 60 kg N ha −1 as a starter dose with rhizobial inoculation could contribute to the high yield, while protein could be altered by N amount, independently on genotype.

Nitrogen Uptake from Different Sources by Non-GMO Soybean Varieties

“…Water shortages lead to reduced plant height [36], particularly when they occur at the stage of shoot formation. Newark [37] and El Kheir et al [38] have found that insufficient precipitation at this stage may reduce plant height by about 30% to 70% [39]. In the present work, mean root mass developed by cultivars was lower in 2018 when, in June, precipitation exceeded 70 mm and plants did not have to develop an extensive rooting system to increase water supply from the soil.…”

“…It was also observed that soybean plants produced lower seed mass in 2018 than in 2017, which was probably due to high temperatures and insufficient precipitation. Mandić et al [39,43] and Ghassemi-Golezani and Lotfi [44] have found that drought occurring during the reproductive period (July-August) causes seed dieback, reduces seed size, shortens the period of seed fill and, as a result, reduces seed yield. According to Purcell et al [45] and Sinclair et al [46], nitrogen content in plants may decline due to insufficient precipitation (water stress) and increased temperatures, which was also confirmed in the work discussed here.…”

Dry Matter Yield of Maize (Zea mays L.) as an Indicator of Mineral Fertilizer Efficiency

“…Starter (row) fertilization increases the soil–fertilizer contact by placing nitrogen in the soil zone with a higher root concentration. This in turn increases the effectiveness of this method of sowing a nutrient [ 35 , 36 ].…”

Genotype and Sowing Time Effects on Soybean Yield and Quality

“…These yield components are strongly conditioned by each other, and the maximum yields are achieved when they are optimally balanced, because a change in one component is only to a certain extent compensated by changes in another. The dry stress during summer months in 2017 caused yield loss due to a decrease in the yield component traits, similarly to Mandić et al [20]. Therefore, the recommendation for soybean growers is to sow at the beginning of April, so that the plants can make the most of the available precipitation.…”