Applying both biochar and phosphobacteria enhances Vigna mungo L. growth and yield in acid soils by increasing soil pH, moisture content, microbial growth and P availability

Abstract Rainfed black gram (Vigna mungo L.) production in low pH alfisol is severely hampered by the sporadic and greater intensity of rainfall as well as low availability of soil phosphorous. Developing suitable management practices is critical to mitigating the ill effects of rainfall variability and low phosphorous availability. Applying biochar, a soil conditioner produced from various bio-waste has been suggested to improve soil moisture content and carbon level. Similarly applying phosphobacteria, a bio-inoculant can enhance P availability to black gram crops. However, the interaction between biochar and phosphobacteria application in low pH Alfisol under rainfed conditions is not fully explored. To fill this knowledge gap, field experiments were conducted to assess the effect of biochar and Bacillus megaterium var phosphaticum (Pb-1) on the availability of phosphorous, black gram growth, and yield. The factors tested were redgram stalk biochar and Australian acacia biochar, enriched farmyard manure, phosphobacteria, and phosphorus fertilizer and their various combinations. Biochar application at 5 t ha−1 increased soil moisture retention and reduced the penetration resistance. The addition of biochar with phosphobacteria positively enhanced the plant physiological parameters such as leaf area, stomatal conductance, SPAD, and reduced the leaf temperature. Application of redgram stalk biochar at 5 t ha−1 with phosphobacteria 2 kg ha−1 recorded higher organic carbon (4.7 g kg−1), soil available P (30.9 kg ha−1) and P uptake (4.6 kg ha−1), by 27, 28 and 45 percent respectively over P fertilizer alone applied treatment. The same treatment combination also recorded the highest seed yield (262 kg ha−1) implying the combined application of biochar and phosphobacteria has the potential to enhance black gram production in rain-fed low pH Alfisols.