Effects of Cattle Biogas Effluent Application and Irrigation Regimes on Rice Growth and Yield: A Mesocosm Experiment

Biogas effluent (BE) is a potential source of fertilizer for rice. Alternate wetting and drying (AWD) irrigation based on surface water level can increase rice grain yield (GY), but its effect under BE application still unclear. To test whether AWD GY application, we conducted mesocosm experiment screen-house conditions in Can Tho, Vietnam. We measured growth three nitrogen (N) treatments—zero-N (Z), synthetic (SF), BE—and two regimes—continuous flooding (CF) with re-irrigation threshold 15 cm below the soil surface. Chlorophyll content (SPAD) leaf color chart (LCC) values were higher SF than BE, plant height was comparable. Although not significantly different between CF AWD, increased it by 12% relative to CF. All N use efficiency (NUE) indices (apparent recovery, agronomic NUE, internal NUE) comparable SF. The results indicate that feasible cattle combination improve GY.