Optimizing productivity, profitability and the carbon–energy nexus of the mustard–mungbean cropping system with micronized sulphonated urea

Sandeep Kumar^1,2Sanjay Singh Rathore^1*Kapila Shekhawat^1*Rajiv Kumar Singh¹Subhash Babu¹Naveen Singh¹Shiv Prasad¹Ravi Kumar¹Mohammad Hasanain^1,3*SUNIL KUMAR PRAJAPATI¹Avaneesh Kumar¹Vinod Kumar Singh⁴

• ¹ICAR - Indian Agricultural Research Institute, New Delhi, India
• ²ICAR National Bureau of Soil Survey & Land Use Planning, Nagpur, India
• ³Division of Agricultural Physics, ICAR-Indian Agricultural Research Institute, New Delhi, India
• ⁴ICAR - Central Research Institute for Dryland Agriculture, Hyderabad, India

Widespread sulfur (S) deficiency in India is attributed to crop intensification, use of S free fertilizers, reduced sulfur dioxide deposition, etc which is one of the major factors for low oilseed productivity and quality. At present whatever conventional S fertilizers used by the farmers, exhibit low S recovery (~10%). However, the novel fertilizers like micronized sulfonated urea (MSU) such as Sulphonated urea II (US-II) contains 10% N and 75% S and Sulphonated urea I (US I) contain 40% N and 13% S with slow reales nature, have shown potential to improve nutrient use efficiency, soil health and productivity. Although, research on these novel fertilizers is limited, especially with regard to dosage and timing of application and its comparative assessment with conventional S fertilizers on productivity, profitability and/ or on energy, carbon footprints in mustard-mungbean cropping system (MMCS). Therefore, a study was conducted to evaluate MSU (US-I and II) with ammonium sulfate (AS), bentonite S (BNT) and SSP, applied 100% basal or split (50% basal + 50% as top dressing). The US II strategic application (15 kg S ha-1 at sowing and 15 kg S ha-1 at 30 days after sowing), significantly (P=0.05) improved system productivity (17.14%) followed by US I (16%), ammonium sulfate (6%) and bentonite S (5.14%) over NPK with no S. This treatment has also enhanced oil content (5.69%), protein content (1.81%-mustard; 1.29%- mungbean) and net returns (mustard; 28.13%; mungbean; 14.16%). Further, carbon output (CO2 e ha-1), carbon sustainability index, eco-efficiency index ($ kg-1 CO2e) and energy use efficiency (MJ ha-1) were higher under US-II, which were 15370, 4.27, 0.49 and 0.17, over S unfertilized plot, where the values of these parameters were 12706, 3.38, 0.39 and 0.14, respectively. The CO2 emissions intensity (1.06 CO2e kg-1 seed) is decreased under US-II strategic application over no S unfertilized plots (1.28 CO2e kg-1 seed). The study concluded that US-II (15 kg S ha-1 at sowing and 15 kg S ha-1 at 30 days after sowing) improved MMCS productivity, protein and oil content, profitability and carbon-energy-nexus of MMCS over conventional S fertilizers (ammonium sulfate, bentonite S, SSP) and S unfertilized plot