Assessment of the different-aged fall-layered drained soils current state (on the example of the Nadezhdinskaya drainage system in the Jewish Autonomous Region)

The article gives an assessment of the uneven-aged fallow drained soil current agrochemical state. The drained uneven-aged fallow meadow gley soils (Haplic Gleysols) of the Nadezhdinskaya drainage system at the Jewish Autonomous region have been researched by the author. The soils structural analysis was carried out with the dry sifting method use. Abandoned drained soils show a direct correlation between fallow age and biodiversity. The absence of anthropogenic activity for 15 years is accompanied by the tree layer growth resumption. With a long absence of agricultural cultivation of soils, there is an accumulation of plant mass and proliferation of root systems (on a 5-year fallow, a 4–5 cm thick turf layer is formed, on a 15-year fallow, the turf layer reaches a depth of 10-15 cm). This leads to loosening of soil horizons. On 15-year-old fallow lands, an increase in the humus content is observed as compared to arable land. At the same time, the greatest decrease in the values of salt and hydrolytic acidity is noted in the 15-year-old fallow soil. In terms of acidity, agricultural soils are neutral. In 5- and 15-year-old fallow lands, a decrease in acidity to slightly acidic values was revealed, which is the result of agrochemical measures cessation and acidifying effect of decomposing plant litter. In the soil under the forest, the soil reaction is acidic. Investigation of phosphorus and potassium mobile forms content in soils of arable land sown with soybeans shows an average value of P₂O₅ and very high value of K₂O. On long abandoned lands it is observed a decrease in phosphorus concentration to its low content, and in potassium – to an average one. Perhaps, these processes are due to hydromorphism increase at the drainage system degradation. Further studies of the drainage system will give us an answer to this question.