Influence of Long-Term Mineral Fertilization on Soil Microbiota, Organic Matter Content and CO2 Emissions

The objective of this study is to analyse the effect of different long-term fertilization treatments on soil microbiological and chemical properties and CO2 emissions on cropped soils. The fertilization treatments were N, P, K, NP, NK, PK, NPK, 0, which have been applied constantly for 64 years on four agricultural crops (wheat, barley, corn and beans) in rotation, in two replicates. The study was conducted on Haplic Chernozem soil type. The highest organic carbon content was observed in the treatments NPK (1.54%) and NP (1.53%), and the lowest in the control (0.97%). On average, of all measurements, CO2 emissions were largest in NP (96.28 kg ha−1 day−1), NPK (93.13 kg ha−1 day−1) and PK (79.40 kg ha−1 day−1) treatments. Strong positive correlation of mineral nitrogen with electrical conductivity, strong negative correlation with pH and moderate positive with soil organic carbon content were found. The amount of available potassium had the strongest effect on the count of actinomycetes and microbial biomass carbon. There was a positive correlation of CO2 emissions with soil organic carbon stocks and mineral nitrogen content. Long-term fertilization with NPK and NP led to enhanced accumulation of organic matter and higher available nutritious, in comparison to unfertilized soil.