Effect of crop rotation on organic carbon and microscopic fungi abundance in maize (Zea mays L.) fields soil

The abundance of microscopic fungi was investigated in permanent black fallow, extensive mono crop (without fertilizer and herbicides), intensive mono crop (fertilizer+herbicide), pre-farm, fodder and intensive rotation maize crop fields soil at the beginning (BBCH 14) and the end of growing season (BBCH 89). Organic carbon (Corg) content was also determined. Fungal abundance in the soil of the maize fields studied was higher at the end of the growing season than at the beginning, except for the extensive mono crop field soil. The most abundant fungi were found in the 0–5 cm and 6–10 cm soil layers at the beginning of the growing season and in the 0–5 cm and 11–20 cm layers at the end of the growing season. The most stable and abundant fungi were found in intensive rotation, where intercropping and green manure are used. The maize fields studied were arranged in the following order according to the highest average number of microscopic fungi in the soil: intensive > forage > pre-farm > extensive mono crop > intensive mono crop > black fallow. The highest number of Trichoderma fungi, which are the main decomposers of residues in agricultural fields, were found in both mono-crop maize fields, and the lowest – in the pre-farm and intensive rotation field’s soil. Trichoderma was almost absent in permanent black fallow soil. The biggest content of Corg was in intensive and fodder rotations, probably due to use of legume-cereal mixtures and cumulative cultures as a pre-crop. The most significant Corg decreases of were caused by reseeding mono crop and the use of permanent black fallow. No statistically reliable relationship was found between Corg and the number of fungi in the rotations.