Unravelling the Potential of Rice Residue - Boosting Wheat's Productivity, Profit, and Soil Health with Varying N Levels

Rice residue burning poses a significant challenge in the rice-wheat cropping system of India, leading to environmental pollution, health issues, and substantial nutrient loss. To combat this menace, a three-year study (2020-21 to 2022-23) was conducted, investigating the effects of rice residue retention (RRR) and rice residue incorporation (RRI) at graded N levels (0, 50, 100, 150, and 200 kg/ha) alongside farmers' practices. The primary objective was to enhance wheat productivity, profitability, and soil fertility within this system. Pooled analysis revealed that RRR outperformed RRI at lower nitrogen doses, while RRI excelled with 7.5%, 7.4%, and 10.0% higher biological yields at higher nitrogen doses (100, 150, and 200 kg/ha). The success of RRR and RRI was attributed to 10.5% and 5.0% higher effective tiller/m2, respectively, compared to farmers' practices at 150 kg N/ha. Notably, RRR exhibited superior NDVI values at the flag leaf stage (0.76) over farmers' practices (0.73). At the 150 kg N/ha, RRR displayed a 9.6% lower cost of cultivation compared to farmers' practices, with 19.6% higher net returns at lower N levels (50 kg/ha), suggesting its greater benefits under low-input conditions. Furthermore, RRR showed the highest benefit-cost ratio (2.75) at 150 kg N/ha, followed by RRI (2.59) and farmers' practices (2.55). Over the three-year period, RRR significantly increased organic carbon content (0.49-0.54%) compared to the initial value (0.38%), affirming its long-term benefits. Consequently, the adoption of RRR by farmers is a preferable eco-friendly option over RRI and present practices for enhancing wheat productivity within the rice-wheat system. Due to 60-65% saving of fuel with the practice of zero tillage along with rice residue retention, it can reduce CO2 emission by 120 kg/ha, therefore, its implementation can reduce CO2 release by 1.62 MT in South Asia per year. Ultimately, it can meet the target of Paris Agreement of limiting global warming to 1.5 degrees C above pre-industrial levels and reaching net-zero CO2 emissions globally by 2050.