Water and nitrogen dynamics in a cultivated soil after a long term of urban compost application
Résumé
The need of realistic site specific and local studies still exists for developing sustainable urban
compost application practices. We conducted a field study to quantify the impact of compost on soil
water dynamics, solute transport and nitrogen release. I
n addition to the monitoring of soil water
potential and water content using tensiometers and TDRs, a tracer study was carried out to
evaluate the effect of compost application on the transport of non
-
sorbing conservative solutes in
soil. The dynamics of n
itrogen was evaluated by sampling destructively the soil to measure its
mineral nitrogen content. The deterministic soil
-
crop model PASTIS was used to simulate the
observed water and N dynamics. Compost application affected the soil water properties only i
n the
upper tilled horizon by increasing its water holding capacity and reducing cumulative evaporation
under high evaporative demand. This could be explained by the increase in soil organic matter
content after 10 years of compost application. Simulated N
fluxes showed that the application of
urban composts increased nitrogen availability for plants. Compost with high biodegradability
presented higher nitrogen release the year following its application, while composts with low
biodegradability allowed long
term availability of N after several years of compost application.
Simulated N fluxes showed the application of organic amendments increased losses of nitrogen,
which can be related to cropping practices. This means that, waste compost use in agriculture
could be a sustainable practice provided that application is adjusted according to the specific
characteristics of compost and management practices