Depot stability of locally injected ammonium and effect on the metabolism of spring wheat

作者：Menge Hartmann Ute^*; Schittenhelm Siegfried

来源：Landbauforschung Volkenrode, 2008, 58(3): 235-245.

• wheat
• CULTAN
• ammonium injection fertilization
• depot stability
• N metabolism
• nitrate reductase
• glutamine synthethase
• yield
• yield components

In order to successfully implement the CULTAN (Controlled Uptake Long Term Ammonium Nutrition) fertilization technique, in which ammonium injection depots are created to reduce N losses, a monitoring of both the stability of these depots as well as of the effects of possible N transformations on the metabolism of plants is required. Spring wheat (Triticum aestivum L.) was planted in twoyear pot experiments with locally injected di-ammonium-phosphate solution (NH4-N) compared with conventional surface applied calcium nitrate (NO3-N) and a control without N fertilisation (-N). On all three harvest dates, the N status and pH values of soil zones were determined, and the concentrations of inorganic cations, total nitrogen, soluble protein and metabolites, as well as the activity of marker enzymes for N-metabolism were measured in the plants.
At the beginning of stem elongation, nitrate due to nitrification accumulated in the periphery zones of the ammonium depot, but this was no longer discernible in the two later harvest dates. Furthermore, a differing reduction of the soil pH value was found depending on depot zone. The uptake and assimilation of the nitrate by the ammonium-fertilized plants possibly contributed to a lessening of the commonly observed toxicity symptoms under ammonium nutrition. Only some of the effects typical for the ammonium nutrition, such as low concentrations of inorganic cations and organic anions, as well as higher amide concentrations could be observed at the beginning of the stem growth, while in later stages, there were no differences to the NO3-N plants. It can be assumed that nitrate developed through nitrification under CULTAN fertilization is continuously taken up by ammonium fertilized plants and thus reduces the risk of N losses through nitrate leaching.

• 出版日期2008-9