Soil hydrothermal regime in apple orchards of different ages and its regulation (case study of the orchards in the M.A. Lisavenko Research Institute of Gardening of Siberia)

Abstract

The development of gardening in the Altai Region is possible only if irrigation reclamation is used which is determined by the extremely continental climate of the region. The research goal is to study the water regime of chernozem during the growing season to determine the deficit of available moisture in soil profile and calculate irrigation rates for apple tree cultivation. It was found that in the rows of older apple trees the daily accumulated temperature was lower than under young ones by 4-11°C. Thus, plants themselves regulate heat distribution in the chernozem profile. Moisture storage under old-aged apple trees was higher than in a younger orchard since the apple trees about 20 year-old created a more favorable water regime the reason for which was due to the decrease not only of physical evaporation under the influence of shading but also in transpiration due to its slowdown and partial drying out of the crown. Throughout the entire soil profile of chernozem in the summer of 2004, in orchards of different ages, a deficit of available moisture remained. Therefore, in a younger orchard, there was a need to use irrigation rates of up to 1400 t ha for one meter thickness, and in the arable layer, respectively, 450 t ha. In the old-aged orchard, the productive moisture storage corresponded to the rank of “good” until mid-August, and only in September they dropped to “poor”. Under apple tree plantations of 1996, in 2005, in the upper 20 cm layer, a significant moisture deficit was revealed already in early June and reached 49 mm, and then it continued until the end of the growing season. Therefore, significant irrigation rates were required. As a result, the water regime in such garden in the summer of 2005 was more intense throughout the entire soil profile. In the old-aged orchard, the amount of available moisture and, consequently, its deficit over the years of research changed to a lesser extent throughout the chernozem profile. This indicated that with the age of plants, fluctuations in the hydrothermal regime during the growing season decreased, i.e. it became more conservative.