Influence of fertilization standards of crops of 5-field crop rotation on the balance of humus and elements of mineral nutrition of sod-podzolic soil in Polissia conditions

Abstract

Goal. To study the influence of fertilizer standards on the balance of humus and mineral nutrition elements of crops of a 5-field grain-row-crop rotation on sod-podzolic soil in conditions of radioactive contamination of Zhytomyr Polissia. Methods. Field (identification of reliable differences in the influence of fertilizer systems on fertility, biological activity and pollution with heavy metals and radionuclides of soil and crop production); measuring-weight (establishment of quantitative indicators of crop yield of crop rotation); laboratory (determination of the content of humus, nutrients, heavy metals, radionuclides in the soil, quality of agricultural products); mathematic (analysis of variance and statistical processing of data for reliability of the obtained research results). Results. The study was conducted in a stationary field experiment during 2015 – 2019 on the territory of the village Khrystynivka (Narodnytsk district, Zhytomyr oblast). It was established that the applied fertilization standards for crops of 5-field grain-row-crop rotation (oats — lupine — spring triticale — fodder beets — corn for grain) and the crop rotation factor had a significant impact on the positive balance of humus and NPK elements, especially phosphorus and potassium. In particular, the use of the one norm of fertilizers provided a deficit-free balance of humus for crop rotation at the level of +0.07 t/ha (intensity of balance — 99%), with the highest values for growing corn for grain (+0.67 t/ha). A negative nitrogen balance was noted for crop rotation on the background without fertilizers ( – 255.4 kg/ha), while application of the first fertilizer norm stabilized the nitrogen balance to 0.6 kg/ha, and the second to 6.6 kg/ha. Phosphorus and potassium turned out to be the most stable elements; their balance in the average crop rotation for applying the 1st fertilizer dose was 37.7 and 18.5 kg/ha, the 2nd — 71.8 and 101.2 kg/ha, respectively. Conclusions. The application of mineral fertilizers in one dose helped to stabilize the balance of humus and the formation of a deficient or positive balance of nutrients. The use of an increased dose of phosphate and potassium fertilizers (second dose) provided a significant improvement in the balance of phosphorus and potassium, but did not always compensate for the lack of nitrogen, especially for the cultivation of highly productive crops.