Compost and Biochar Amendments Enhanced the Growth, Yield, Nutrient Uptake, Nitrogen- and Water-use Efficiency of Irrigated Corn

Compost and biochar, serving as carbon-enriched recyclable amendments, play important roles in enhancing soil quality to sustain crop productivity. In this study, the synergistic effects of compost and biochar, individually and in combination, along with varying irrigation rates on corn (<i>Zea mays</i>) growth and productivity were investigated. The controlled pot-culture experiment, utilizing Arik clay soil, explored factorial combinations of compost and biochar at different rates (0%, 2%, and 5% of soil) and irrigation levels (50%, 75%, and 100% of field-moisture capacity, FMC). Averaged across biochar and irrigation treatments, compost amendments at a 5% application rate significantly enhanced corn performance. This resulted in a 56% increase in grain yield and substantial improvements in agronomic nitrogen use efficiency (aNUE) and physiological nitrogen use efficiency (pNUE), which increased by 145% and 150%, respectively, compared to the control. Water-use efficiency (WUE) also improved by 33% compared to the control. Biochar application at 5%, while slightly less impactful, still yielded notable benefits, including a 14% increase in grain yield, and improvements in WUE (14%), aNUE (66%), pNUE (40%), and apparent nitrogen recovery efficiency (aNRE) (74%) over the control. Irrigation at 100% FMC enhanced yield (9–25%) and aNUE, pNUE, and aNRE by 25%, 50%, and 89%, respectively. However, it reduced WUE by 64% and led to diminished root distribution compared to irrigation at 50% FMC. Noteworthy was the significant interaction between compost and irrigation, particularly influencing WUE of corn. In conclusion, integrating compost, biochar, and strategic irrigation can collectively exert positive effects on corn growth, yield, nutrient uptake, NUE, and WUE, offering valuable insights for sustainable agricultural practices and resource optimization.