Soil Nutrient Status and Microbial Communities as Influenced by Bio-Fuel Trees Plantation

Abstract

Due to the depletion of fossil fuel reserves that increased environmental problems presently the world has been confronted with an energy crisis. The field study on soil nutrient status and microbial communities as influenced by bio-fuel trees plantation was carried out in Bio-Fuel Park, Madenur, Hassan District of Karnataka state, India during pre and postmonsoon of 2017-2018. The objective of this study was to assess the soil nutrient status and microbial communities under the 4 trees species namely Simarouba glauca, Madhuca latifolia, Azadirachta indica, Calophyllum inophyllum, in their root zone depths such as 0-15 cm, 15-30 cm and 30-45cm depths during pre and post-monsoon seasons. The results revealed that in post-monsoon season recorded significantly higher in soil pH (5.96) and EC (dSm-1) (0.11) but in soil OC (0.72%) and available N (335 kg ha-1), P2O5 (30.43 kg ha-1), K2O (236.9 kg ha-1) was recorded higher in pre-monsoon. Among bio-fuel species recorded higher significantly, C. inophyllum had strong influence on soil pH (6.53) and available P2O5 (36.04 kg ha-1). The S. glauca record higher in the following EC (dSm-1) (0.14), OC (0.81%),available N (350 kg ha-1), K2O (293.8 kg ha-1). Influences among soil depth was highly recorded in depths of 15-30 in available K2O (224.7 kg ha-1), P2O5 (37.09 kg ha-1), N (323 kg ha-1 each) and in depths 0-15 recorded higher in organic-C (0.73%, EC (dSm-1) (0.14), but in soil pH significantly higher at depth of 30-45 cm (5.86). The correlation matrix between microbial characters and chemical characters was significantly negative, a correlation between the total bacteria and soil pH (r2 = -0.494) and EC (r2 = 0.558). The ph supported the growth of Azotobacter (r2 = 0.593). PO4-solubilizers microorganisms (MO) significantly correlated with organic-C and available-N. The study provides evidence that bio-fuel trees species are contributing a positive impact to soil microbial and soil nutrients in particular trees species in a different manner. Pre-monsoon was highly supporting the growth of microbial and supporting the availability of the soil nutrients compared to post-monsoon. And environmental factors are also influencing the growth of microbial communities, infinite conclusively indicate most of the microbiological characters weak to a very strong relationship in maintaining good soil health at a landscape level. So Calophyllum inophyllum and Simarouba glauca followed by Azadirachta indica and the least was Madhuca latifolia, the first two bio-fuel trees are the initiative plants for the restoration of barren and Weakland.