Utility of the end-of-season nitrate test for nitrogen sufficiency of irrigated maize under Mediterranean semi-arid conditions
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Date
2015
Authors
Isla Climente, Ramón
Salmerón, Montserrat
Cavero Campo, José
Yagüe Carrasco, María Rosa
Quílez, Dolores
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Abstract
Calibration of decision tools to improve N fertilizer management is critical to increase its adoption by maize (Zea mays L.)
growers. The objective of this study was to establish nitrate and total nitrogen concentrations in the basal maize stalks (BMS) at
harvest to separate maize fields among three N availability categories (N-deficient, N-optimum, and N-excess) under Mediterranean
irrigated semiarid conditions. We analysed data from 26 irrigated maize trials conducted between 2001 and 2012. Trials included
treatments receiving different N fertilizer rates and sources (mineral and organic), irrigation systems (flood, sprinkler) and soil types.
The critical nitrate concentration in BMS to identify N-deficient plots (CNC L ) is affected by the irrigation system. The CNC L was
lower under sprinkler irrigation (708 mg NO 3– –N/kg) than under flood irrigation (2205 mg NO 3– –N/kg), and the later presented a
higher degree of uncertainty compared to sprinkler irrigated systems. The results showed the difficulty to identify the N-deficient
plots with the BMS test and the higher sensibility of nitrate-N than total-N concentration in BMS to separate N-deficient from
N-optimal plots. Under sprinkler irrigation, nitrate in BMS>1500 mg NO 3– –N/kg had a 85% probability of having received an excess
of N. Considering economic net returns to N fertilization, the range of nitrate concentration in BMS that maximized profit under
sprinkler-irrigated conditions was established between 1100 and 1700 mg NO 3– –N/kg. Results suggest that BMS test can be useful
in detecting plots with an excess of N but considering irrigation efficiency is crucial for stablishing successful CNC thresholds.
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Spanish Journal of Agricultural Research, 2015, vol. 13 núm. 1, p. 1-12