Results from four Pinus patula water planting trials in the summer rainfall region of South Africa

Abstract

Planting with water is used by some forestry companies in South Africa to reduce post-planting water stress. Four trials were implemented to test the response in survival of Pinus patula to water applied at planting. Two trials each were situated in the KwaZulu-Natal Midlands and Mpumalanga escarpment. The first trial at each site was planted in spring (October) and the second in summer (February). Watering treatments consisted of different quantities of water used in the planting operation and included 0.5l, 2l, 4l and no water. At all sites the planting treatment affected the depth at which the seedlings were planted. Only at the spring-planted trial in the KwaZulu-Natal Midlands was survival of the dry-planted seedlings significantly lower than that of the seedlings planted with water from 90d after planting. This may have been due to low rainfall during the week before and two weeks after planting, or the small size of the seedlings. Application of 0.5l of water to the planting pit at this trial was sufficient to increase survival to a level equivalent to that where 2 or 4l of water was used, yet only increased soil moisture in the area immediately surrounding the seedling. Future research should aim to investigate the importance of seedling quality as well as the method of application of water to the planting hole on post-planting survival.