Gaseous N Losses from Winter Wheat¹

Abstract

Research monitoring N uptake by various agricultural crops has shown total N accumulations in the plant to increase prior to the growth stages around heading to flowering with a subsequent decrease in total N occurring after flowering. Volatilization of N from the plant may account for much of this loss as well as account for some of the deficits exhibited in N balance studies. Experiments were conducted in a gas‐tight growth chamber to determine what role plants alone may play in the overall loss of N from the soil‐plant system. Winter wheat (Triticum aestivum L.) was established, vernalized, and grown to maturity in the growth chamber. At first internode elongation, the chamber was closed and sealed for the duration of the experiment. Air supplied to the chamber during this period was bubbled through 1 N H2SO4 to remove ambient NH3 and through a reagent specific to NO and NO2 to remove these gases. Air samples were continuously drawn from the chamber and bubbled through 0.2 N H2SO4 to trap evolved NH3. These samples were collected weekly and analyzed using steam distillation. A second portion of the air sample was washed through the NO‐NO2 specific reagent and analyzed colorimetrically. Only trace amounts of NO and NO2 could be found at any time during the experiment leading to the conclusion that volatilization of these gases does not contribute significantly to the loss of N from the plant. Ammonia volatilized from the system at the rate of 0.34 to 0.89 ✕ 10−1 mg NH3‐N/m2/day prior to flowering. After flowering the rate of NH3‐N evolution increased to 1.03 to 1.32 ✕ 10−1 mg/m2/day. This dramatic increase in the rate of NH3‐N evolution at flowering coincides with the plant growth stage that researchers have begun to observe deficits in total N accumulations in the above ground portion of the plants. This data supports the hypothesis forwarded here, that volatilization of NH3 from plant tissue can partially account for the deficits in total N accumulation observed in plant tissue following flowering.

Influence of organic matter and inorganic fertilizer on the growth and nitrogen accumulation of corn plants

“…Downloaded by [New York University] Monitoring N accumulation by various agricultural crops has shown that the total N accumulations in the plant increase prior to the growth stages around heading to flowering, with subsequent decrease in total N occurring after flowering. Volatilization of N from the plant may account for much of this loss as well as account for some of the deficits exhibited in N balance stueies (Hooker, 1980;Stutte and Weiland, 1978;Stutteetal., 1979;Weiland and Ta, 1992). Therefore, the decrease in total N accumulation of Chem-N treatment could be due to the volatilization of N from tissues at high N concentration in the soil.…”

Perda de nitrogênio pela Brachiaria decumbens após a antese: relação com a umidade do solo

“…Os autores Tabela 1 -Massa de matéria seca (g vaso -1 ) e nitrogênio total (mg vaso -1 ) da raiz, parte aérea e planta toda de capim-Brachiaria. HOOKER et al (1980), em experimento de condições controladas (atmosfera), constataram no período de pós-antese que o acúmulo de N diminuiu sensivelmente em plantas de trigo, passando de 14g m -2 para 10g m -2 , dez dias após o florescimento. Os autores constataram também aumento na concentração de NH 3 na armadilha montada para capturar gases emitidos pelo sistema solo-planta, em que a concentração de amônia passou de 2mg m -2 , no momento do florescimento, para próxima de 6mg m -2 30 dias após.…”

“…Isto porque, nos estádios reprodutivos (pós-antese -início da senescência), há aumento do potencial de emissão de NH 3 devido às mudanças no metabolismo do N no vegetal, uma vez que ocorre maior clivagem de proteínas e aminoácidos nesses estádios (MORGAN & PARTON, 1989). HARPER et al (1987) (HOOKER et al, 1980). Dessa maneira, o NO 2 seria a fonte para a volatilização de NO 2 e NO x via corrente transpiratória, resultando em perdas de N via parte aérea das plantas.…”

A simulation model-assisted study on water and nitrogen dynamics and their effects on crop performance in the wheat-maize system I: The model

“…Mono dimensional vertical soil water movement in the root zone can be calculated by ignoring effects of temperature, solutes and hysteresis (Gong, 1994;Hooker and Sander, 1980;Wang, 1999) as follows:…”

“…NH 4 -N is ignored in this model because its content in dryland soils is usually very small (Aslyng, 1985). NO 3 -N, on the other hand, is very mobile in the irrigated soil and is depicted with a mono-dimensional dynamic equation (Hooker andSander 1980, Aslyng 1985) as y y y y y y…”