Effects of agronomic practices on the physico-chemical properties of soil waters in rice culture

Authors: MUHAMMAD FARRAKH NAWAZ, GUILHEM BOURRIE, FABIENNE TROLARD, JEAN-CLAUDE MOURET, PIERRE HENRY

Abstract: Lowland rice cultivation under hydromorphic conditions is a very dynamic system due to continuous rhizospheric interactions and these interactions are largely influenced by anthropic interventions. Understanding of continuous biogeochemical changes and the effects of environmentally friendly residue management practices on this system is crucial for the sustainability of rice culture. Two rice-cultivated plots with different residue management practices-one with buried residues and the other with burnt residues-were studied by in situ monitoring of the soil solution to understand the quick changes in the dynamic medium of rice culture. In this study, 2 multiparametric probes, each consisting of measurement cells and internal memory, were used to determine automatically pH, Eh, temperature, and electrical conductivity (EC) of soil solution every hour throughout the entire rice growing period. The results showed that biogeochemical reactions are largely influenced by irrigation and fertilization practices. Incorporation of rice residues resulted in more reductive conditions and higher temperatures as compared to burning of rice residues. Fourier and covariance analyses showed that there existed a period of 24 h for EC, pH, and temperature while there was no period for redox potentials, which suggested the existence of daily variations in rice culture possibly related to solar cycles.

Keywords: Fourier analysis, covariance, multiparametric probe, redox conditions, rice residues

Full Text: PDF