Ecological regimes of soils of the Novgorod region drained by open drainage

In the natural and climatic conditions of the Novgorod region, the ecological regimes of lands drained by various open drainage structures were studied: channels through 70 m (control), runoff hollows in combination with the strips of cultivation, reclamation, and closed drainage. During the operation (1992-2021) of open drainage structures, the agrochemical state of soils changed: the exchange acidity decreased; the humus content increased by 2-3 %, with the exception of a combination of hollows with a reclamation strip (a decrease of 1.5 %); the content of mobile phosphorus and potassium decreased. The formation of groundwater regimes and moisture reserves on drainage systems depends on meteorological conditions, which in the last 5 years have been very diverse: from slightly arid (2020, HTC = 1.1) to excessively moist (2017, HTC = 2.65). The systems of runoff hollows in combination with the reclamation strip provided the lowest groundwater level, while in an extremely wet year they did not rise into the arable horizon. The most favorable moisture regime of the root-inhabited soil layer in excessively humid 2017 and subsequent years was noted on systems of runoff hollows with closed drainage in combination with reclamation strips. During dry periods, which are usually June-July, a lack of moisture in the root layer of the soil was observed on experimental systems of runoff hollows in combination with cultivation and reclamation strips. The most acute moisture deficiency in these periods (0.45 full capacity) was noted on systems combining runoff hollows with cultivation strips. The most favorable soil moisture regime (0.65-0.85 full capacity) was in the combination of hollows with closed drainage and a reclamation strip. The formed new ecological regimes of the soils drained by the hollow-strip method had a significant impact on the hay yield of perennial grasses (Phleum pratense, Festuca pratensis). The increase in yield compared to the control averaged 0.3-0.6 t/ha over 5 years.