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Fertilizer ammonium : nitrate ratios determine phosphorus uptake by young maize plants
Author(s) -
Pedersen Ingeborg F.,
Sørensen Peter,
Rasmussen Jim,
Withers Paul J. A.,
Rubæk Gitte Holton
Publication year - 2019
Publication title -
journal of plant nutrition and soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 1436-8730
DOI - 10.1002/jpln.201800553
Subject(s) - rhizosphere , phosphorus , chemistry , nitrogen , nitrification , ammonium , shoot , fertilizer , agronomy , manure , nutrient , phosphate , biology , bacteria , biochemistry , genetics , organic chemistry
We investigated the interacting effects of inorganic nitrogen and the main inorganic phosphorus form in dairy manure (dicalcium phosphate, CaHPO 4 ) on growth, nutrient uptake, and rhizosphere pH of young maize plants. In a pot experiment, three levels of CaHPO 4 (0, 167, and 500 mg P pot −1 ) were combined with nitrogen (637 mg N pot −1 ) applied at five NH 4 ‐N : NO 3 ‐N ratios (0 : 100, 25 : 75, 50 : 50, 75 : 25, and 100 : 0) and a nitrification inhibitor in a concentrated layer of a typical acid sandy soil from Denmark. 15 N‐labeled NH 4 ‐N was applied to differentiate the role of nitrification and to partition nitrogen uptake derived from NH 4 ‐N. Among treatments including nitrogen, shoot biomass, rooting and phosphorus uptake were significantly higher at the five‐leaf stage when CaHPO 4 was applied with NH 4 ‐N : NO 3 ‐N ratios of 50 : 50 and 75 : 25. In these treatments, rhizosphere pH dropped significantly in direct proportion with NH 4 ‐N uptake. The fertilizers in the concentrated layer had a root‐inhibiting effect in treatments without phosphorus supply and in treatments with pure NO 3 ‐N or NH 4 ‐N supply. Increased nitrogen uptake as NH 4 ‐N instead of NO 3 ‐N reduced rhizosphere pH and enhanced acquisition of applied CaHPO 4 by young maize plants, which may have positive implications for the enhanced utilization of manure phosphorus.