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Seasonal rainfall distribution drives nitrogen use efficiency and losses in dryland summer sorghum

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Rowlings, D. W., Lester, D. W., Grace, P. R., Scheer, C., De Rosa, D., De Antoni Migliorati, M., Friedl, J. and Bell, M. J. (2022) Seasonal rainfall distribution drives nitrogen use efficiency and losses in dryland summer sorghum. Field Crops Research, 283 . p. 108527. ISSN 0378-4290

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Article Link: https://doi.org/10.1016/j.fcr.2022.108527

Publisher URL: https://www.sciencedirect.com/science/article/pii/S0378429022000983

Abstract

Nitrogen (N) fertiliser inputs represent one of the largest variable costs in dryland cropping systems, and a key determinant of water-limited yield. Despite extensive research into microbial N losses via intermediate denitrification products such as N2O, limited research exists on total N losses, and the effect of increasing soil N surplus has on fertiliser use-efficiency is not clear. In this study, the fate of banded urea fertiliser N across crop uptake, soil residual N and N losses was determined using the 15N recovery technique over nine trials with four N rates (0, plus low, medium and high industry rates) across N responsive and non-N responsive sites over 3 years in dryland sorghum (Sorghum bicolor). On average, crop uptake efficiency ranged from 50% at the low and medium N rate (80 kg N ha−1) to < 38% at the highest N rate, and was as low as 5%. Nitrogen losses averaged 26.5% across all rates and trials. At the medium N rate, losses exceeded 18% in all trials, despite relatively dry seasons, and in some trials exceeded 34%. Losses of N were driven by large cumulative rain events and high early-season rainfall. In dryland systems, the inability of crops to acquire banded N fertiliser can potentially leave fertiliser stranded in the topsoil, leaving it vulnerable to losses.ga1

Item Type:Article
Business groups:Crop and Food Science
Subjects:Agriculture > Agriculture (General) > Agricultural meteorology. Crops and climate
Agriculture > Agriculture (General) > Methods and systems of culture. Cropping systems
Agriculture > Agriculture (General) > Fertilisers
Plant culture > Field crops > Sorghum
Live Archive:11 Apr 2022 04:51
Last Modified:11 Apr 2022 04:51

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