Leffelaar PA ,
Langeveld CA ,
Hofman JE ,
Segers R ,
Pol-Dasselaar van den A van ,
Goudriaan J ,
Rabbinge R ,
Oenema O
42 p
in Dutch
2000
Toon Nederlands
English Abstract The integrated nitrous oxide (N2O) and methane (CH4)
grassland project aims to estimate and explain emissions of these greenhouse
gases from two ecosystems, namely drained agricultural peat soil under grass
at the experimental farm Zegveld and undrained peat in the nature preserve
Nieuwkoopse Plassen. Peat soils were chosen because of their expected
considerable contribution to the greenhouse gas budget considering the
prevailing wet and partial anaerobic conditions. The emission dynamics of
these ecosystems are considered representatives of large peat areas because
the underlying processes are rather general and driven by variables like
organic matter characteristics, water and nutrient conditions and type of
vegetation. The research approach comprises measerements and modelling at
different integration levels relating to the microbiology of the production
and consumption of N2O and CH4 (laboratory studies), their movement through
peat soil (rhizolab and field studies), and the resulting fluxes (field
studies). Typical emissions from drained soil were 15-40 kg ha-1 y-1 N2O
and virtually zero for CH4. The undrained soil in the nature preserve
emitted 100-280 kg ha-1 y-1 CH4, and probably little N2O. The process
knowledge collected and partly integrated in the models helps to explain
these data. For example, the low methane emissions from drained peat can
more coherently be understood and extrapolated because (i) upper soil layers
are aerobic, thus limiting methane production and stimulating methane
oxidation, (ii) absence of aerenchymatous roots of wetland plants that
connect deeper anaerobic soil layers where methane is produced to the
atmosphere and supply labile carbon, (iii) a low methane production
potential in deep layers due to the low decomposability of organic matter,
and (iv) long anaerobic periods needed in the topsoil to develop a methane
production potential.
