Jacob F. Evans, Maya Weinstein

The objective of the present study was to examine whether we could improve the aeration of sandy soils and clayey soils that had been degraded by longterm irrigation with treated wastewater (TWW) through drip irrigation with TWW aerated with oxygen (O2) nanobubbles (ONB). A lysimeter set-up was irrigated using surface and subsurface drip systems, and the effects of those systems on soil oxygen concentration, greenhouse gas emissions [i.e., nitrous oxide (N2O)], and crop physiology and yield were investigated. In both soils, irrigation with ONB-aerated TWW improved oxygen availability in the root zone. This, in turn, significantly reduced cumulative N2O emissions, improved plant physiology and resulted in increased yield (though not always significantly). Our results imply that irrigation with ONB-aerated TWW may be a cost-effective way to alleviate soil hypoxia, especially in parts of Israel and the world where clayey soils have been degraded by prolonged irrigation with TWW. Such practices will result in a win-win situation where the farmer increases his revenue while reducing fertilizer losses to the environment.