Residual effects of previous crops on soil respiration, nitrogen mineralisation and N2O emission

Summary

Models for simulating nitrogen leaching are often based on simulations of a number of individual processes in the soil, such as turnover of organic matter, nitrogen mineralisation and immobilisation, nitrification, denitrification etc. It has been found that the models used under Danish conditions (DAISY and/or FASSET) have some limitations especially concerning the turnover of organic matter with implications on e.g. soil respiration. Therefore, the models are being modified and for calibration of the model measurements of in situ soil respiration using a portable CO2-analyser, nitrogen mineralization using a field incubation technique and N2O emission using a static chamber method, were carried out during the growing season 2001. The measurements were carried out on bare soil but with different previous crops in 2000 representing two cropping systems with different input of organic matter. Results are summarised in the table below.
Previous crop Soil respiration N mineralisation N2O emission
kg CO2-C ha-1 kg N ha-1 kg N ha-1
Grass-clover 4109 91 2.7
Pea-barley/grass 4268 93 3.3
Pea-barley 4320 90 2.6
Winter wheat 3435 70 2.6