Food-energy‑carbon nexus of Himalayan okra–pea cropping system: Impacts of AM-fungi, precision phosphorus and irrigation regimes in an acid Alfisol

Abstract

Conventional farming practices are energy and carbon-intensive. Low-cost technologies like AM-fungi (AMF) and precision P-management vis-à-vis precision irrigation-scheduling may enhance P-bioavailability, and crop- and water-productivity with reduced energy and carbon-footprints in acid-Alfisol of north-western Himalayas. Hence, an experiment was done in okra (Abelmoschus esculentus)-pea (Pisum sativum) cropping system (OPCS) using AMF (Glomus mosseae) at three inorganic-P levels (50, 75 & 100 % of soil-test based P-dose) and two irrigation-regimes (40 & 80 % AWC). AMF-inoculation significantly enhanced the system-productivity (∼11 %), bio-energy output (∼8 %) and SOC-storage over non-AMF plots in OPCS. Carbon-input use followed the trend of water>diesel>fertilizers> FYM > herbicides> pesticides>AMF in OPCS. AMF-inoculation significantly reduced the carbon-footprints (0.466 kg CO2-e kg−1) by ∼10.2 % over non-AMF plots. Soil-test based 100 % P-dose significantly enhanced the system-productivity (6.3–15.6 %) and bio-energy output (4.7–12.6 %) with lesser carbon-footprints (5.3–15 %) over 50 and 75 % P-dose. Irrigation at 80 % AWC enhanced system-productivity (∼4.1 %), however at 40 % AWC reduced carbon-footprints by ∼11.7 % besides saving irrigation-water by ∼24 % (150 mm ha−1/year) in OPCS. Hence, farmers must necessarily use AMF-inoculation coupled with soil-test based P-fertilization (75–100 %) while preserving a balance in irrigation water-use at 40–80 % AWC depending upon water-availability for higher crop- and water-productivity besides lesser energy and carbon-footprints in OPCS in Himalayan acid Alfisol.