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Strategic adaptation of nitrogen management for El Niño Southern Oscillation-induced winter wheat system

Reshmi Sarkar, Brenda V. Ortiz, Kipling S. Balkcom
Mitigation and adaptation strategies for global change 2017 v.22 no.3 pp. 369-398
El Nino, La Nina, Triticum aestivum, climate, crop yield, decision support systems, global change, growing season, leaching, nitrogen, rain, sandy loam soils, silt loam soils, winter wheat
The rainfall anomaly (RA) associated with El Niño-Southern Oscillation (ENSO) has various unwanted impacts on agricultural system globally. The loss of inorganic nitrogen (N) depending on extreme wet or dry conditions is a major concern. The main objective of this study was to adapt site-specific N strategies to mitigate the effects of ENSO on yields of winter wheat (Triticum aestivum L.; WW) system. After thorough calibration and evaluation, Decision Support Systems for Agrotechnology Transfer (DSSAT, version 4.5) model suite was adapted. Seasonal analysis was used to compare the variability in simulated leached-N, N uptake, and WW yields under long-term historical real-weather conditions. The site X climate interactions and impacts of weather factors on WW yields were assessed across 60 growing seasons in three phases of ENSO: El Niño (EN), La Niña (LN), and neutral (NT). Based on RA, the simulated yields were lower during LN than EN (11 %) and NT (12 %) on coastal sandy-loam soils and higher during LN than EN (13 %) and NT (8 %) on heavy silt loam soils at valley. N strategy with basal of 22 kg N ha⁻¹ + a split of 112 kg N ha⁻¹ at Feekes (F) 4 stage of WW was adapted for maximum yield and minimum N leaching during LN at valley and NT at coastal sites. However, basal of 22 kg N ha⁻¹ + two equal splits of 56 kg N ha⁻¹ at both F4 and F6 was found as the most adaptable N strategy during both EN and NT phases at valley and EN and LN at coastal sites.