Effect of the water regime, crop rotation and fertilizers in biogenic matters leaching into ground water and surface water

The purpose of our work was to establish features of formation of filtration processes and to define prevention measures towards the nutrients leaching from drainage soils into the ground waters. Our researches were carried out on typical drained floodplain soils of Panfil Research Station, Institute of Agriculture of National Academy of Agrarian Science (floodplain of Supiy River, Yahotyn district, Kiev region, Ukraine) in 2016-2018. The arable layer of peatlands had high level of decomposition (50-60%) with gross nitrogen contamination of 1.9%, phosphorus - 0.4, potassium - 0.17 and sodium - 7.1%, which is typical for the forest-steppe zone. The drying and humidifying system was satisfactory. Research on nutrient washing into ground water was carried out on various agricultural lands, during and out of crop rotation. iltration water was taken from water measurement wells, from drainage canals and directly from the Supi River twice a year (in autumn and spring) on sites with different fertilisation schemes. We found that in the fields with perennial grasses without mineral fertilizers 4.9 mg L-1 of NO3 was washed out, 11.7 mg of K2O, and 130 mg of CaO; on the fertilized fields it were 4. 2-19.4, 12.8-22.2, and 122-148 mg L-1 respectively; on the annual crop fields without the fertilizers a total of 9.2 mg L-1 of NO3, 16.8 of K2O and 134 mg L-1 of CaO were leached, whereas it were 14.3-19.6, 21.2-34.4 and 138-161 mg L(-1)on the annual crop fertilized fields in the humid years. We observed a similar dependence in the dry 2018 year. Our observations of nutrient wash-out showed that on the fields with perennial grasses and annual crops (winter rye and corn) there were much more wash-out of nitrate and ammonium nitrogen, mobile phosphorus and potassium in autumn compared to spring for average from 2016-2018. In addition, the autumn drainage water contains more carbonates and had higher content of Na2O (up to 48.7-51.3 mg L-1). We did not register the dependence of nutrient washing into the ground water on the cultivated crops. At the same time, a significant amount of calcium and magnesium was washed out from perennial and annual crop fields in spring.