Simple heat profiles and biogeochemical patterns for analysis the influence on soil microbial community of plastic-greenhouse and open field condition

Abstract

The diversity of the soil microbial community is remarkably sensitive to different cropping techniques. To examine the effects of cultivation in a greenhouse on the soil microbial activity and diversity, we collected soil samples from vegetable crops continuously grown in a plastic greenhouse (G) and an open field (N). Heat profiling was obtained using microcalorimeter in the presence of different carbon sources. Power time curves were recorded after glucose and ammonium sulphate supplementation. The total heat release QT (Jg-1), maximum heat flow Pmax (μW) and growth rate constant k (h-1) are higher in G treatment group than the in N treatment group. On the other hand, the time (tmax) to reach the peak heat flow is lower in G treatment group compared to N treatment group, as is cell specific heat rate JQ/N (J cell-1). Sample G1 has the highest Pmax (1246.07 μW) and the lowest tmax (11.86 h); in contrast, sample N5 has the lowest Pmax (411.03 μW) and the highest tmax (21.78 h). The microbial community in the soil was estimated from phospholipid fatty acid (PLFA) biomarkers analysis and a viable count, followed by a subsequent determination of the physicochemical parameters. The total average PLFA concentration range is found as 129.76 - 142.54 nmol g-1. Both thermodynamics properties and PLFA concentration was are significantly greater in G1, G2 and G3 treatment than in the other two (N5 & N6) management systems (P < 0.05). Combination of both thermodynamic and PLFA profiling determines that the microbial population is higher in the soil from the greenhouse fertilization than from the open field cultivation. This novel approach could be applicable to a better understanding of (i) the changes in the soil microbial community in green house and open field cultivation practices, and (ii) the relationship between physicochemical properties and soil microbial community’s diversity. Moreover, this would be a notable technique for the decision maker to choose the potential cultivation method for sustainable green-food development program.