Annotation

The objective of the paper was to study the impact of drip irrigation by the water of unfavorable composition on the indices of humus state of ordinary chernozem: humus content, the content of soluble humus substances and humin, humic acids coupled with calcium, and humification level. The experiments were conducted at the high tunnels and virgin plots situated alongside. The irrigation water had the Cl-SO4-Na composition and its mineralization was 3300 mg/dm3 , electrical conductivity was 3.55 dS/m . The main impact of drip i rrigation was observed in the upper soil layer 0-20 cm where the indices of humus state were impaired. More specifically, the humus content decreased during the vegetation period by 1.1 %, the humification level was poor (18.9 %) against to medium (25.1 %) at virgin plots, the reduction of soluble humus substances and increasing of humin content was ob served. So, the ratio of soluble humus substances under drip irrigation was 34 % and at the virgin plots – 63 %. Humus type didn’t change under the influence of drip irrigation and complied with the type for given soil. Both at irrigated and virgin plots, the humus type was fulvic-humic or humic. The water quality has an impact on the content of humic acids coupled with calcium. At irrigated plots this index was in average lower by 8.1 % compared to virgin plots. While using drip irrigation by the water of unfavorable composition the measures for simultaneous increasing the content of organic matter and calcium in soil have to be provided.