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Medientyp:
E-Artikel
Titel:
Impact of potassium on plant uptake of non-exchangeable NH 4 + -N
Beteiligte:
Beuters, Patrick;
Scherer, Heinrich W.;
Spott, Oliver;
Vetterlein, Doris
Erschienen:
Springer, 2015
Erschienen in:
Plant and Soil, 387 (2015) 1/2, Seite 37-47
Sprache:
Englisch
ISSN:
0032-079X;
1573-5036
Entstehung:
Hochschulschrift:
Anmerkungen:
Beschreibung:
<p>Aims and background Release of 'non-exchangeable' NH4+-N from interlayers of 2:1 clay minerals is postulated to depend not only on soil solution NH4+-N concentration but also on the concentration of K+ and Ca2+. Concentrations of all three cations are altered in rhizosphere compared to soil solution at larger distance from the root surface. Methods Non-exchangeable NH4+-N pool was labelled with 15N. Treatments including application of K+, Ca2+ and K+ + Ca2+ were established. In a compartment system approach we analysed changes in soil solution concentrations of 15NH4+-N, 15NO3−-N, K+ and Ca2+ in situ at different distances from the root surface over time and related them to the release of non-exchangeable 15NH4+-N and uptake of 15N by plants. Results and conclusions The 15N enrichment in plant tissue was significantly lower in treatments with K+ application compared to those without. This was in line with smaller depletion of non-exchangeable 15NH4+-N in the rhizosphere for these treatments and also with lower 15N abundance in soil solution NO3−-N fraction. Hence, K+ application hampered the release of NH4+ from the interlayers. A promoting effect of increasing Ca2+ concentrations on release of non-exchangeable NH4+-N could not be evaluated since the Ca2+ concentration in soil solution was largely controlled by small amounts of carbonate contained in the substrate and thus the addition of Ca2+ did not result in a relevant increase of soil solution Ca2+ concentration as originally intended. The use of 15N to follow the fate of non-exchangeable NH4+-N proved very useful as it provides a higher sensitivity for all measured fractions compared to total N. However, as soil N fractions equilibrate with each other labelling one fraction exclusively is not possible.</p>