Soil Organic Matter Degradation in Long-Term Maize Cultivation and Insufficient Organic Fertilization
2020
Jiří Balík | Martin Kulhánek | Jindřich Černý | Ondřej Sedlář | Pavel Suran
Soil organic matter carbon (CSOM) compounds degradation was observed in long-term field experiments with silage maize monoculture. Over a period of 26 years, the content of carbon in topsoil decreased by 22% in control unfertilized plots compared to 25% and 26% in treatments fertilized annually with mineral nitrogen. With annual wheat straw application (together with mineral N), the content of CSOM decreased by 8%. Contrary to that, the annual application of farmyard manure resulted in a CSOM increase of 16%. The ratio of carbon produced by maize related to total topsoil CSOM content ranged between 8.1&ndash:11.8%. In plots with mineral N fertilization, this ratio was always higher than in the unfertilized control plots. With the weaker soil extraction agent (CaCl2), the ratio of carbon produced by maize was determined to be 17.9&ndash:20.7%. With stronger extraction agent (pyrophosphate) it was only 10.2&ndash:14.6%. This shows that maize produced mostly unstable carbon compounds. Mineral N application resulted in stronger mineralization of original and stable organic matter compared to the unfertilized control. However, the increase of maize-produced carbon content in fertilized plots did not compensate for the decrease of &ldquo:old&rdquo: organic matter. As a result, a tendency to decrease total CSOM content in plots with mineral N applied was observed.
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