Echinochloa stagnina improves soil structure and phytodesalinization of irrigated saline sodic Vertisols
Résumé
AimThis study tested the capacity of the semi-aquatic grass Echinochloa stagnina to grow on highly salt-affected soil to improve soil structure and decrease salinity of saline Vertisols.MethodsThe experimental study, conducted over 11months on soil columns in laboratory conditions, tested three treatments: i) ponded bare soil without crops (CT), ii) soil cultivated with E. stagnina (CEs) in two successive cropping seasons and (iii) soil permanently cultivated with E. stagnina (CEp) with a staggered harvest.ResultsSoil porosity increased when cultivated with E. stagnina but remained constant under bare soil. At the end of the experiment, soil cultivated with E. stagnina had higher macroporosity (6-9%) than bare soil (3-4%), linked mainly to root development. Moreover, salt stock, which was initially similar in the columns, decreased by 65-87% in soil cultivated with E. stagnina and by 34-45% in ponded bare soil. Salt accumulation in plant biomass contributed 22-35% of soil desalinization vs 65-78% due to leaching. In addition, E. stagnina produced 10-12t.ha(-1) (dry weight) of forage in 11months, which makes it of economic interest for farmers.ConclusionsAn irrigated E. stagnina crop appears effective at improving physical properties and reducing salinity of Vertisols and also at producing forage. Future studies must be performed with modeling approaches that use hydrodynamic parameters to characterize phytodesalinization of Vertisols by E. stagnina.