Scientific Journal of KubSAU

Nitrogen supply of soils is an important factor in the successful cultivation of agricultural crops. Nowadays, in the Central Black Earth region there are planted orchards with high density of trees, with installed systems of drip irrigation and fertigation. Such orchards are relatively new, particularly in this region. Fertigation ambiguous effects on soil structure and its content of nutrients, especially hydrolysable nitrogen. Therefore, the study of the distribution of hydrolysable nitrogen in the soil under the influence of fertigation and drip irrigation is important. The aim of our research was to investigate the distribution hydrolysable nitrogen in the root soil layers 0-20, 21-40, 41-60, 61-80 cm. Investigations were carried out according to conventional methods. In these layers of the soil, we have determined the content of hydrolysable nitrogen and yield. As a result, we have found that in variants with fertigation were the highest yield. In addition, with fertigation it was noted higher content of hydrolysable nitrogen in the soil as compared with the control without irrigation, especially in the deep layers 21-40; 41-60 and 61-80 cm. It was also noted increase of hydrolysable nitrogen in the soil along the periphery of the wetting

There are given the results of long-term research of different forms of soil nitrogen content and their relationships with the content of total nitrogen in leaves and yield. It was detected a strong positive correlation among them hydrolyzable nitrogen content in the soil and total nitrogen content in the leaves and yield. It is proposed the use of this index for diagnostic of soil nitrogen supply

Soil profiles were made in intensive apple orchard in the agricultural enterprises in Lipetsk and Tambov regions in 2015. Drip irrigation in year rates of 500-550 m3 was carried out since 2010. During the research we determined the soil density, the solid phase density, aggregate composition, particle size distribution, the content of hydrolyzable nitrogen and humus by conventional methods. As a result of drip irrigation can increase dust-like fraction in dark gray forest soil, whereas in chernozems this index did not change significantly. In the black earth soil was noted the process of increasing the proportion of mud fraction due to mineral part chernozem destruction. In both soil types was increased sand content. It was found that drip irrigation improves some of the soil water-physical properties, such as a soil structure coefficient and the content of agronomical valuable aggregates in a layer of 20-40 cm. There was also noted that with increasing soil depth was reduced humus and hydrolyzable nitrogen content. In aggregate analysis, it was found that dark-gray forest soil the amount of water-stable aggregates increased, while meadow chernozem leached soil decreased. Data of the aggregate analysis revealed that in the dark-gray forest soil the amount of water-stable aggregates increased as a result of drip irrigation, while in meadow chernozem leached soil decreased. It recommends by drip irrigation application permanent monitoring of the soil humus content