Vertical distribution of soil weed seed banks and comparison of seed bank estimation methods in a tropical agroecosystem

This study aimed to compare the wet sieve extraction (direct count) and seedling emergence methods for quantifying and characterising soil weed banks across three depth increments in a tropical agroecosystem. Soil seed banks are critical reservoirs of weed propagules, yet accurate and reliable assessment remains methodologically challenging. Both methods were evaluated across soil depths of 0–10, 10–20 and 20–30 cm using a completely randomised design with 10 replicates at Tamil Nadu Agricultural University, Coimbatore. Wet sieving recovered far more seeds (310, 239 and 73 seeds per sample) than emergence (39, 19 and 12 seedlings per sample), with both methods showing significant depth declines (p < 0.001). Five weed taxa were recorded, namely Portulaca oleracea L., Amaranthus spp., Trianthema portulacastrum L., Echinochloa spp. and Dinebra spp. Wet sieving was appeared to be more effective in recovering the overall seed population, whereas the seedling emergence approach appeared more useful for identifying a wider range of species, particularly grasses. The combined use of both methods may therefore provide complementary information for preliminary assessment of soil weed seed banks under tropical conditions.