Efficiency of agromeliorative practices for restoring soil fertility in irrigated apple orchards

The paper presents the results of studies into the impact of agromeliorative practices conducive to mitigating the negative eff ects of drip irrigation with mineralized waters on the fertility of chernozem soils and the productivity of intensive apple orchards. The study is aimed at assessing the biological effi ciency of agromeliorative practices designed to reduce the adverse eff ects of irrigating apple orchards with mineralized irrigation waters. The study objects included typical chernozems and intensively irrigated apple orchards on M9 rootstock in the steppe fruit-growing zone of Krasnodar Krai. The effi ciency of practices aimed at leveling negative soil processes was established through the combined application of phosphogypsum at a rate of 5 t/ha and straw mulching at a thickness of 15 cm in the near-trunk areas of apple orchards. The study revealed a tendency to increase the content of mobile phosphorus compounds in the local soil moistening zone in experimental variants with the introduction of phosphogypsum. Mulching of the soil in the near-trunk areas resulted in improved potassium nutrition for apple trees, an increase in the content of mobile potassium compounds in the near-trunk area soil from 53 to 343 mg/kg and a growth in total potassium content in the leaves by 0.22 % dry matter compared to the control group. The combined use of phosphogypsum and straw mulch decreased the content of mobile potassium compounds by 26-79 mg/kg of soil. The nutrient content in the leaves of apple trees in all experimental variants revealed optimal and elevated levels with a noted reduction in sodium cation content in the leaves by 17.9-35.7 % when employing agromeliorative practices. The use of phosphogypsum alone in early spring improved calcium nutrition and signifi cantly increased fruit set of apple trees in the fi rst year of ameliorant application. Complex use of phosphogypsum and soil mulching led to a reliable growth in average fruit weight by 6.8–8.8 % and increased yield of apple trees from 4.2 to 7.5 t/ha. Furthermore, more prolonged dissolution of ameliorant under the mulching layer was noted, which promoted gradual water-soluble calcium intake into the soil.