Critical Nitrogen Concentration Declines with Soil Water Availability in Tall Fescue

ABSTRACT The diagnosis of the N status of crops is based on the concept of critical N concentration (Ncr), which is the minimum N concentration in shoot biomass (SB) required for maximizing growth. A reference curve of Ncr decrease (Ref‐Ncr) with SB increase proposed for C3 species (Ref‐Ncr=48 SB‐0....

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Published in:Crop science 2014-01, Vol.54 (1), p.318-330
Main Authors: Errecart, Pedro M., Agnusdei, Mónica G., Lattanzi, Fernando A., Marino, María A., Berone, Germán D.
Format: Article
Language:English
Subjects:
Agricultural production
Crops
Evapotranspiration
Fertilizers
Grasses
Moisture content
Nutrition
Plant growth
Regrowth
Soil water
Water availability
Water management
Water stress
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Summary:ABSTRACT The diagnosis of the N status of crops is based on the concept of critical N concentration (Ncr), which is the minimum N concentration in shoot biomass (SB) required for maximizing growth. A reference curve of Ncr decrease (Ref‐Ncr) with SB increase proposed for C3 species (Ref‐Ncr=48 SB‐0.32) was validated for several crops growing without water deficiency in different sites and seasons; however, the validity of Ref‐Ncr is uncertain when water is limiting. The objective was to assess whether water stress affects Ncr. Five regrowths of a temperate‐type tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] were followed during autumn, spring, and summer in Balcarce, Argentina. Several N rates were applied and SB accumulation and N concentration were measured in each of four to six sequential SB harvests performed at every regrowth. SB, Ncr, available soil water, reference evapotranspiration (ET0), and real evapotranspiration (RET) were estimated. Ncr agreed well with Ref‐Ncr when soil water was nonlimiting, but it was consistently lower than Ref‐Ncr whenever crop RET was reduced (RET/ET0
ISSN:0011-183X
1435-0653
DOI:10.2135/cropsci2013.08.0561