Energy budgeting, carbon footprint and economics of sunflower and pigeonpea system under moisture conservation practices in rainfed semi-arid tropics

In drylands, soil water availability in the profile during crop period, especially at critical stages is most vital. System which is productive, energy efficient with a minimum carbon (C) footprint under limited water condition is a concern. Therefore we evaluated sunflower and pigeonpea crops over two-years in terms of productivity, energy, C-footprint and profitability under different moisture conservation measures. These were raised bed, ridge and furrow, tied ridges and furrow, conservation tillage, flatbed sowing and opening furrow after every three rows at 30 days, and flatbed sowing under sole crops of sunflower and pigeonpea and intercropping at 1:1 adopted split-plot design. The results showed in-field moisture conservation by ridge and furrow produced considerably greater sunflower (59.6–66%) and pigeonpea (85.2–128.7%) yields and profitable (604.1 US$ ha⁻¹) over traditional flatbed sowing. It also exhibited greater output energy (37.8–83.0%), energy use efficiency(4.2 kg GJ⁻¹),and lower energy intensity (21.57 × 10⁻³ GJ US$⁻¹). Sunflower and pigeonpea sole crops produced higher seed yields over intercropping. But it has yield advantage in terms of greater pigeonpea equivalent yield (0.53–1.13 Mg ha⁻¹), profitability (691.8 USD ha⁻¹), output energy (42.4 GJ ha⁻¹) and energy ratio. Among the input energy sources, chemical fertilizers accounted 53.6 % of the total input energy. Interestingly, least C-footprints were recorded under ridge and furrow (182 kg CE kg⁻¹grain)and intercropping (0.248 kg CE kg⁻¹ grain). Results confirmed sunflower and pigeonpea intercropping on ridge and furrow was productive, energy saving, C-footprint reduction and economical practice under rainfed condition.