TECHNIQUES FOR SPEEDING THE MOVEMENT OF LIME INTO AN ORCHARD SOIL

Many soils in orchards in southern British Columbia are acidic, especially those with sandy texture. Most orchards have vegetative ground cover. A field experiment was therefore undertaken on a sandy soil to determine the most effective method of getting lime into the rooting zone of fruit trees without damaging their roots. Applying lime on the grass surface at 3.6 t ha−1 was as effective in reducing soil acidity of the 0- to 25-cm horizon as incorporating lime into the soil. Calcium hydroxide, calcite and dolomite were all equally effective in raising soil pH. Doubling the liming rate greatly increased the downward neutralization of soil acidity and movement of Ca and Mg. The pH was raised by about 1 unit throughout the profile by the higher rate of Ca(OH)2, (7.2 t ha−1). Ammonium sulphate detracted from the benefits of liming, with the 200 kg N ha−1 rate causing a significant depression in pH at the 0- to 20-cm depth. Ammonium nitrate had a smaller adverse effect. Hence, neutralization of soil acidity ...