Results of a ground-water level and nitrogen fertilizer field experiment with apple trees on a marine clay soil

This paper summarizes and reviews some of the results of a 12-year experiment which was carried out in order to examine drainage requirements of apple trees on a newly reclaimed soil. The experiment involved production of Cox's Orange Pippin and Golden Delicious apples, grafted on M9 rootstock, that were planted on 11 different ground-water regime plots which were split into three nitrogen treatment sub-plots. It was found that there was a distinct variation in amounts of shoot growth, apple production nitrogen mineralization, and fruit quality on account of variations in the ground-water regime. No optimum ground-water regime could be established. This optimum may be quantified by using the capital budgeting decision procedure. The optimum nitrogen concentration in mid-shoot leaves, however, was found to be 2.3 and 2.4 percent of dry matter for Golden Delicious and Cox's Orange Pippin respectively. This report has been printed as a book with 266 pages, 96 figures, and 112 references. The book can be obtained from Ijsselmeerpolders Development Authority, P.O. Box 600, 8200 AP Lelystad, The Netherlands. Price of the book is D.Fl. 69,-and it includes postage.