Performance of onion varieties under different organic manure combinations

Abstract:

"Feed the soil, not the plant" is an old gardener’s proverb, but how well does it hold for onion — a crop notorious for its shallow roots and heavy nutrient appetite? This research compared four onion varieties (Cream Gold, Red Baron, Creamgold Supreme, Early Pearl) grown under three organic manure regimes (farmyard manure at 20 t ha⁻¹, composted green waste at 15 t ha⁻¹, and vermicompost at 8 t ha⁻¹) on a sandy loam at Perth, Western Australia, during the 2023 winter season. Creamgold Supreme under vermicompost produced the highest marketable bulb yield (37.4 t ha⁻¹), 27.8% above the same variety under FYM. Vermicompost outperformed the other two manures for all four varieties, driven by its higher nitrogen availability and faster mineralisation in the warm Perth winter ^[1]. Bulb size distribution shifted toward the premium 60–80 mm grade under vermicompost (64.3% of harvest vs 48.1% under FYM). Variety × manure interaction was significant for yield (p = 0.006) and total soluble solids (p = 0.021). These data support vermicompost as the preferred organic input for high-value onion production in Mediterranean-climate regions of Western Australia.