Managing N inputs in wheat production systems is an important issue in order to achieve máximum profitable production, and minimum negative environmental impact. The aim of this investigation carried out in dry land farming in the Vojvodina province (Serbia) was to estimate the effects of different N fertilization levels (0, 75, and 150 kg N ha-1) on some quantitative traits, rain-use efficiency (RUE), N agronomic efficiency (NAE), and N use efficiency (NUE) in two Serbian winter wheat (Triticum aestivum L.) cultivars 'Pobeda' and 'Renesansa'. 'Pobeda' had higher grain yield (4437 kg ha-1) and RUE (8.32 kg ha-1 mm-1) than 'Renesansa' (4265 kg ha-1 and 8 kg ha-1 mm-1, respectively). Grain yield (4652 kg ha-1) and NUE (31.46 kg kg-1 N) were higher in the 2010-2011 season (favorable weather conditions) than in the 2011-2012 (4050 kg ha-1 and 27.59 kg kg-1 N, respectively). The highly significant effect on grain yield (4396 and 4494 kg ha-1), RUE (8.24 and 8.45 kg ha-1 mm-1), NAE (3.11 and 2.21 kg kg-1 N) and NUE (58.62 and 29.96 kg kg-1 N) had levels of 75 and 150 kg N ha-1. NAE and NUE declined at high N rates. Based on the results of this study, farmers should be advised that the use of large amounts of N increases production costs and reduce the economic benefits. The increase in wheat production is possible by selecting adapted genotypes with improved NUE

During post-harvest maturation, different species vary in the length of dormancy breaking or germination increases. Seed dormancy and slow seedling development often limit establishment of forage grass stands. Seed germination and seedling vigour of Italian ryegrass (Lolium italicum A. Braun, Synonym Lolium multiflorum L.), cocksfoot (Dactylis glomerata L.) and timothy (Phleum pretense L.) were observed after harvest and storage. After harvest in June, seeds were stored under standard storage conditions and sampled every 30 days after harvest (DAH), up to 270 DAH, and then every 60 days up to 990 DAH. At each date, seeds were tested for final germination percentage and for seedling vigour traits. Timothy seeds had a maximum germination (88%) and the best seedlings vigour at 90 DAH, which implies that early autumn (September-October) is the best sowing period for freshly harvested seeds of timothy. Timothy seed germination was poor from 270 DAH (73%). The best germination and vigour of Italian ryegrass and cocksfoot seedlings were between 270 and 330 DAH, which equates to spring sowing time (March-April) in the succeeding year. Cocksfoot and Italian ryegrass seeds maintained satisfactory germination levels up to 630 DAH (81%) and 810 DAH (81%), respectively. The data can serve for the determination of a proper storage duration management between harvest and sowing of the tested species under ambient conditions of south-eastern Europe.

Rainfall is one of the most important environmental factors influencing crop production under dry land farming conditions. In the Republic of Serbia, the soybean is produced under rainfed conditions, and therefore online monitoring of the rainfall use efficiency (RUE) is essential for efficient management of production. The research aim was to estimate the effects of amount rainfall during the growing season (RGS) and average monthly rainfall on soybean grain yield (GY) in the Vojvodina during the sixteen year period (2000-2015). Distributions of RGS were not satisfactory and negatively influenced the expression genetic yield potential of cultivars. Rainfall deficits during the growing season limited the soybean plant reproductive growth stages leading to GY loss. The coefficient of variation indicated that RGS and monthly rainfall changed moderately from year to year. Regression equations showed that GY tended to increase with the amount of rainfall. GY had strong positive relationship with RGS and rainfall in May, July and August. Since the amount and distribution of rainfall during growing season are critical determinants of GY, soybean cultivars of shorter vegetation periods should be developed and cultivated so that maximum utilization of rainfall is ensured.

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.

The mineralization of nitrogen in apple orchard soil will increase the soil supply. An incubation study to test the soil potential and the validity of analytical methods was conducted at 3, 8, 15, and 20 °C for up to 128 days on soils from western and south-eastern Norway. Soils with the highest pH showed the highest mineralization. The mineralization increased with increasing temperature and time, but start-up N reduced mineralization. The mineralization cannot be estimated from standard soil chemical parameters because the different C/N ratio indicates organic material of different origin and quality. The increase in NO₃-N started very quickly and ranged from 17 to 182% and 12 to 64% after 8 days at 3 °C and 20 °C, respectively. There was no correlation between total N in the soil and the amount of mineralized N. On average, the mineralization increased by 5–7% for a change of 1 °C in the interval from 8 to 15 °C in the soil. The chemical extraction method using heated KCl correlated well with the mineralization data. On average, the chemical method estimated 30 kg N ha⁻¹, which corresponded to 0.48% of total N. Recommendations for N fertilization based on total N in the soil overestimate the contribution of plant-available N in most cases.

Genotype and Year Effect on Grain Yield and Nutritive Values of Maize (Zea mays L.)