Effect of different methods and techniques of cultivation of sod-podzolic loamy soil on the structure of humic acids and greenhouse gases emission
The effect of three types of cultivation (surface plowing to the depth of 8-10 cm, plowing to the depth of 20-22 cm, plowing to the depth of 28-30 cm) on the structure of the humic acids and greenhouse gases emission of sod-podzolic soil is considered in this work. On the basis of the data obtained from the elemental analysis, lR-spectroscopy and pyrolysis mass-spectrometry the authors revealed that all types of cultivation affect the composition and parameters of humic acids. Comparing humw acids of 0-10 cm and 10-20 cm layers under the type of cultivation to the depth of 8-10 cm with the humin acids of the same layers under the type of plowing to the depth of 20-22 cm, it should be specified that after minimal cultivation humw acids contain more components of the labile part whereas under the moldboard plowing degradation of this part takes place with the specific/ fractional cumulation of the central, nuclear part. Considering average data of the elemental composition of the humw acids in 0-30 cm layer, it should be specified that in magnitude to the atomic H:C ratio the humin acids under the type of cultivation to the depth of 8-10 cm contain the maximum amount of the aliphatic components, the humic acids under the type of plowing to 20-22 cm do not differ greatly in this parameter, and humic acids under the type of plowing to 28-30 cm are characterized by more condensate/fused structure. Their general lability, as well as the quantity of aliphatic and oxygen-containing groups in their composition is increasing under the influence of deeper cultivation. In the composition of the pyrolizates of all humic acids regardless of the type of cultivation the amount of gaseous products almost two times more than the amount of liquid and solid products. The surface cultivation has more protective functions, which include protection of humic acids from degradation; it also prevents the emission of greenhouse gases.