Abstract
Improvements in nitrogen (N) use efficiency in crop production are important for addressing the triple challenges of food security, environmental degradation and climate change. The three fertilizers, calcium ammonium nitrate (CAN), urea (Urea) and stabilized urea (Ureastab), were applied at a rate of 160 kg N ha−1 with two or three splits to winter wheat (Triticum aestivum L.) in the Pannonian climate region of eastern Austria. On average, over all fertilization treatments, the grain yield (GY) increased by about a quarter and the grain N concentration (GNC) doubled compared to the control without fertilization. Consequently, the grain N yield (NYGRAIN) was increased with N fertilization by 154%. The GY increased due to a higher grain density with no differences between N fertilizers but with a tendency of a higher grain yield with three compared to two splits. Three splits also slightly increased the GNC and consequently the NYGRAIN of CAN and Ureastab in one year. The removal of N fertilizer with the NYGRAIN (N surplus) was higher than the amount of applied fertilizer. Fertilization decreased the N use efficiency (NUE), the N uptake efficiency (NUpE) and the N utilization efficiency (NUtE) but increased the soil mineral nitrate (NO3-N) at harvest and the apparent N loss (ANL). Three compared to two applications resulted in a higher NO3-N at harvest but also a lower N surplus due to partly higher NYGRAIN. Consequently, the ANL was lower with three compared to two splits. Also, the NUpE and the apparent N recovery efficiency (ANRE) were higher with three splits. The best N treatment regarding highest above-ground biomass yield with lowest N surplus, N balance and ANL was the three-split treatment (50 CAN, 50 CAN, 60 liquid urea ammonium nitrate). Three splits can, under semi-arid conditions, be beneficial when aiming high-quality wheat for bread-making and also for reducing the N loss. Whereas, two splits are recommended when aiming only at high GY, e.g., for ethanol-wheat production.
Highlights
Nitrogen (N) is a major driver in crop production, but too much nitrogen is harmful for the ecosystems and potentially to human health [1]
Agriculture 2020, 10, 541 especially the fraction of N input harvested as product, is one of the most effective means of increasing crop productivity while decreasing environmental degradation [5]
The grain yield (GY) was highest with Ureastab (50:50:60), Ureastab (100:60:0) and Urea (50:50:60), and lowest for the control with other treatments showing intermediate values
Summary
Nitrogen (N) is a major driver in crop production, but too much nitrogen is harmful for the ecosystems and potentially to human health [1]. Nitrogen management in agriculture aims to achieve agronomic objectives (farm income, high crop and livestock productivity) and environmental objectives (minimal N losses) simultaneously. Agriculture 2020, 10, 541 especially the fraction of N input harvested as product, is one of the most effective means of increasing crop productivity while decreasing environmental degradation [5]. In the global analysis of cropping systems ( including mixed crop-livestock production systems, which use manure N) using the FAO (Food and Agriculture Organization of the United Nations) database, Zhang et al [5] reported a. N output-input ratio (the fraction of N input harvested as product) of 0.42 kg harvest N kg−1 input. The global target annual output-input ratio of N for 2050, using FAO projections for food demand and the allowable N pollution, was calculated with
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