Abstract

Winter wheat grown on a clay soil was subjected to one of four treatments. The control was not irrigated; the drought treatment had screens to divert rainwater; the irrigation and irrigation/fertilization treatments were irrigated using a drip-tube system with liquid fertilizer (200 kg N ha-1 year-1) applied daily in the irrigation/fertilization treatment according to predicted plant uptake. All other treatments also received 200 kg N, but as a single application of bag fertilizer. Soil temperature was monitored. Soil moisture was measured using gravimetric samplings and a capacitance method. Litter bags with barley straw were buried at 10 cm depth in the spring and sampled repeatedly during the growing season. Decomposition rates were calculated assuming exponential decay and that water-soluble components were immediately decomposed or leached from the litter bags. Rates were highly dependent on soil moisture, and the constants ranged from 0.11% day-1 in the drought treatment to 0.55% day-1 in the irrigation/fertilization treatment. A simulation model with driving variables based on Q10 temperature dependence and a log/linear relationship between soil water tension and activity was fitted to the data. The control and drought treatments showed high climate-corrected decomposition constants. The high values were attributed to low and erratic mass loss due to drought, and to low precision in the conversions from water content to tension in the dry range. The irrigated treatments showed good fits, and there was little or no difference in decomposition rates between the two irrigated treatments. The N dynamics of the straw differed considerably between treatments, and the ranking of plots in terms of net immobilization in the straw was control > irrigation/fertilization > irrigation > drought.

Keywords

DECOMPOSITION; SOIL MOISTURE; NITROGEN IMMOBILIZATION; FERTILIZATION; SIMULATION MODELING

Published in

Biology and Fertility of Soils
1993, Volume: 15, number: 1, pages: 1-8
Publisher: SPRINGER VERLAG

SLU Authors

• Andrén, Olof

  • Department of Ecology and Environmental Research, Swedish University of Agricultural Sciences
    

• Kätterer, Thomas

  • Department of Ecology and Environmental Research, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Soil Science


Publication identifier

DOI: https://doi.org/10.1007/BF00336280

Permanent link to this page (URI)

https://res.slu.se/id/publ/44546