Microbial Properties of a Ferric Lixisol as Affected by Long Term Crop Management and Fertilization Regimes in Burkina Faso, West Africa

We used an\r\nongoing long-term field trial established since 1960 in Burkina Faso, to study\r\nthe microbial properties of a Ferric Lixisol under various crop management and\r\nfertilization regimes. Microbial respiration rate, microbial biomass carbon\r\n(MBC) and soil bacteria’s number were assessed in soil samples taken at 0 - 20 cm\r\ndepth. The crop management were continuous cropping of sorghum (Sorghum\r\nbicolor L.) (S/S) and rotation between sorghum and cowpea (Vigna\r\nunguiculata L.) (S/C), while the fertilization regimes were: 1)\r\nControl (te); 2) Low rate of mineral fertilizer (fm); 3) Low rate of mineral\r\nfertilizer + sorghum straw restitution (fmr); 4) Low rate of mineral fertilizer\r\n+ low rate of manure (fmo); 5) High rate of mineral fertilizer (FM); and vii)\r\nHigh rate of mineral fertilizer + high rate of manure (FMO). The manure is\r\napplied every second year. The results indicate that sorghum/cowpea rotation\r\nsignificantly increase MBC and bacteria number as compared to continuous\r\nsorghum cropping. MBC ranged from 335.5 to 54.85 μg C g−1 soil\r\nwith S/S and from 457.5 to 86.6 μg C g−1 soil\r\nwith S/C. Application of high level of manure and mineral fertilizer increase\r\nmicrobial respiration rate and MBC. The highest MBC was observed with FMO and\r\nthe lowest with the control. In general, the metabolic quotient (qCO2)\r\nwas negatively impacted by the fertilization and cowpea rotation. For S/S\r\nrotation, qCO2 of the control was 1.5 to 2 times that of the\r\ntreatments with low mineral fertilizer (fmr, fmo and fm) and 3 times that of\r\nthe high rate of fertilization (FM and FMO). With S/C rotation, qCO2 of the control was 2 times of that fmr, FM and FMO and 0.8 times that of fmo\r\nand fm. Soil bacteria in the fmr were 63.6 and 12.4 times the control in the\r\nS/S and S/C rotations, respectively. In sum, combined application of manure and\r\nmineral fertilizer with crop rotation is the best management practices to\r\nimprove in sustainable way microbial activities in tropical soil.