Waste-liquors generated during Handmade paper manufacture from cow dung as a potential source of biofertilizer

In India, cow dung is widely utilized to create formulations that serve as effective plant growth enhancers with antimicrobial properties. The cow dung-derived handmade paper manufacturing process produces two waste-liquor streams, a Raw Liquor (RL) produced through the dewatering of the cow-dung slurry and a Black Liquor (BL) produced during the soda pulping of dewatered cow dung. The present study explored the potential of these waste streams to be used as plant biofertilizers for germination and cultivation of Vigna radiata seeds (mung bean, IPM-02-03 variety). An in vitro assay for seed germination efficiency and a pot study for plant growth promotion (PGP) activity were used to assess this potential. The in vitro assay demonstrated that nutrient-rich RL, with its 100% seed germination efficiency (better than the 85.7% of tap water) was an effective biofertilizer for seed germination. In contrast, BL yielded poor seed germination efficiency. The pot study showed that water irrigation led to good seed germination, survival, plant rooting and shooting, but it was probably deprived of nutrients for inducing good grain yields. When water was replaced with RL, it was able to replicate the results, but with good grain yields. In contrast, BL produced poorer germination, seed survival and PGP results. The poor biofertilization efficiency of BL was most probably due to the nutrient losses and toxic chemicals produced in the harsh pulping process. The results showed that RL, though considered a waste stream, is sufficiently nutrient-rich to act as an effective biofertilizer for germinating mung bean seeds and promoting plant growth and grain yields.