Comparative effect of mesquite biochar, farmyard manure, and chemical fertilizers on soil fertility and growth of onion (Allium cepa L.)

Mesquite (Prosopis juliflora L.), a noxious weed, needs control and effective utilization for agronomical purposes. A field experiment was conducted to compare the effects of mesquite biochar (MB, 10 tons ha−1), farmyard manure (FYM, 10 tons ha−1), and NPK fertilizers (120:80:80 kg ha−1) on physicochemical attributes of soil and onion traits. Characterization analysis revealed that MB has greater pH (8.6) and EC (0.45 dS/m−1) than FYM (8.1 and 0.24 dS/m−1). Further, pyrolysis produced irregularly shaped mesquite biochar particles embedded with micropores of variant sizes. Soil analysis showed that MB had greater EC (1.47 dS/m−1) than FYM (1.42 dS/m−1) and NPK fertilizers (1.41 dS/m−1). Similarly, MB significantly improved water holding capacity of the soil and contributed more organic matter (0.58%) and NO3–N (2.02 mg kg−1) than other treatments. However, no significant effect of MB treatment was observed on soil Olsen-P. Further, maximum bulb weight (6.13 kg plot−1), leaf length (32.38 cm), total onion yield (268.55 kg ha−1), and total N and K contents in onion bulb were also observed in the plots treated with MB as compared with FYM and NPK fertilizers. In conclusion, MB is a suitable organic amendment to improve soil fertility and plant growth, and may be included in fertilization programs to improve crops yield.