The research has been carried out under production conditions on light gray forest soils with light particle-size composition at an area of 550 hectares where liquid pig manure (LPM) of a large pig breeding complex is annually used as an organic fertilizer at doses of 60 and 90 t/ha. The average characteristics of LPM are as follows: dry matter content is 9.5%, pH 7.7 units, nitrogen 0.22%, phosphorus 0.11%, and potassium 0.12%. The cultivated grain crops were presented by winter and spring wheat varieties, Moskovskaya 39 and Esther, respectively. It has been established that at the dose of 60 t/ha LPM for two years of research at an average a mean wheat yield was 3.0-3.75 t/ha, and at the dose of 90 t/ha - up to 4.75 t/ha. The return on investments for fertilizers in the “winter wheat → spring wheat” crop rotation link at the dose of 60 t/ha of LPM was 5.41 kg of grain per 1 kg of active substance of manure, at the dose of 90 t/ha - 4.57 kg / kg. A positive balance of nutritional elements developed on all fields, but it was better balanced when the dose of LPM was 60 t/ha and the yield was 3.0 t/ha of grain annually, or when the LPM dose was 90 t/ha and the yield of wheat was 4.75 t/ha. In this case, the estimated potassi-um supply of soil occurs at a lower rate than that of nitrogen and phosphorus. The application of 120 t of LPM during two years in total on loamy sand and of 180 t/ha on light loamy soil provided an increase in the content of mobile phosphorus compounds by 5-22 mg/kg, and potassium - by 11-30 mg/kg with a variation coefficient of 28-57% and 21-49%, respectively.
The influence of sediment particle size and organic carbon on toxicity of copper to benthic invertebrates in oxic/suboxic surface sediments
