Effects of tillage practices on yield, carbon emissions and economic benefits of ratoon sugarcane

The sugarcane yield, carbon emissions, and economic benefits of the ratoon sugarcane production system were studied under different tillage practices to provide a scientific basis for guiding the green, low-carbon, and efficient production of sugarcane. A field ratoon sugarcane experiment was conducted on two consecutive ratoon sugarcane crops from 2021 to 2023 in the western Guangdong sugarcane farming area under four tillage practices: control treatment with no fertilizer (CK), farmer practice (FP), integration of water and fertilizer (DF), and integration of water and fertilizer + sugarcane leaf return and mulching (DF+S). In addition, the following were analyzed: soil physical and chemical properties, sugarcane yield, partial factor productivity, fertilizer use efficiency, carbon emissions and footprint, and economic benefits. The results showed that, after two years, the available nutrients of nitrogen, phosphorus, and potassium increased in soils on the sample farms, indicating that the amount of fertilizer applied through farmer practice may be excessive, posing an environmental pollution risk. Compared with the DF treatment, the soil organic matter, available potassium, and exchangeable magnesium content in the DF+S treatment increased by 16.1%, 16.1%, and 28.8%, respectively, indicating that sugarcane leaf mulching can improve soil fertility. Compared with the FP treatment, the yield (over an average of two years) significantly increased by 15.2% and 27.8% in DF and DF+S treatments, respectively. Meanwhile, the partial factor productivity of nitrogen, phosphorus, and potassium fertilizers for the DF and DF+S treatments significantly increased by 107.6% and 130.3%, 41.6% and 57.1%, and 145.7% and 172.5%, respectively. For the same treatments, the use efficiency of nitrogen, phosphorus, and potassium fertilizers significantly increased by 92.6% and 127.7%, 30.1% and 48.3%, 85.3% and 119.6%, respectively. However, carbon emissions decreased by 22.3% and 75.6%, respectively, and carbon footprints significantly decreased by 32.8% and 80.9%, respectively. Consequently, net income increased by 4.3 and 9.8 times, respectively. Moreover, compared with the DF treatment, the yield and net income of the DF+S treatment increased by 10.9% and 103.2%, respectively, whereas carbon emissions and carbon footprints significantly decreased by 68.6% and 71.7%, respectively, which improved the net economic ecosystem budget. Compared to FP, this demonstrated that the integration of water and fertilizer not only reduced fertilizer application but also improved fertilizer use efficiency and yield, resulting in higher profits and lower carbon emissions, indicating a green, low-carbon, and high-efficiency tillage practice. In addition, the integration of water and fertilizer + sugarcane leaf return and mulching significantly increased yield and net income and reduced carbon emissions, consequently improving the net economic ecosystem budget. This tillage practice in ratoon sugarcane production could, therefore, be recommended for simultaneously low carbon emissions, high efficiency, and resultant environmental and economic benefits.