Characterization of Peach Roots in Fox Sand as Influenced by Sprinkler Irrigation and Tree Density

Abstract

Abstract The trench profile method was used to map peach [Prunus persica (L.) Batsch cv. Harken/Siberian C] roots in an 11-year-old experimental orchard with 3 levels of irrigation and 3 tree densities. Roots near the drip line, 150 cm from the trunk, were mapped to a depth of 120 cm, while those 30 cm from the trunk were mapped to a depth of 240 cm. Location, number, and diameter of roots near the drip line were greatly affected by irrigation and only moderately affected by tree density. The total number, and number of small-diameter (<2 mm) roots were highest in nonirrigated plots and decreased with increasing levels of irrigation. A similar but much reduced pattern was evident for medium- (2 to 5 mm) and large- (>5 mm) diameter roots. Irrigation promoted shallow rooting near the drip line. Trees receiving the low and high level of irrigation had 35% and 42%, respectively, of their roots in the top 30 cm of soil, compared with only 18% for those in nonirrigated plots. At depths of 30 to 120 cm in nonirrigated plots, 82% of the roots near the drip line were found in these soil layers, compared with 65% for the low and 58% for the high level of irrigation. Tree density had no effect on total root number near the drip line, although there was an increase in root number with an increase in tree density 90 to 120 cm from the trunk on both sides of the tree, and a decrease in root number with an increase in tree density within 60 cm of the trunk. Rooting occurred readily in the Ap, Bm, and Bt soil horizons, but very little rooting occurred in the gray sand comprising the Ck horizon, which had a high pH (7.8) and poor soil water retention characteristics.