EFFECT OF WATER AND FERTILIZER COUPLING MODES ON SOIL AND LEAF NUTRIENT CONTENTS IN A PEAR ORCHARD

With six- to seven-year-old pear trees, the effect of different water-fertilizer coupling modes on soil and leaf nutrient contents was studied in order to screen out a better combination by referring to some tree growth and development indexes. The results indicated that, the soil alkali-hydrolysable N contents with most treatments were significantly higher than the control in mid-April, with NT and NH treatments being the highest at 0-20 and 20-50 cm soil layers. In late May, the hydrolysable N contents were the highest with NT and NH treatments at 0-20 cm soil layer, significantly higher than other treatments. As for the available P contents, NT and NH treatments were higher. In late July at 0-20 and 20-50 cm soil layers, the hydrolysable N content was higher with NH treatment and it was the highest at 50-80 cm soil layer. The available P content with NH treatment was the highest at 0-20 cm soil layer. At 20-50 cm soil layer the available K content of NT treatment was the highest. In early September, the hydrolysable N contents with NT and NH treatments were the highest at three soil layers. As for available P contents, at 0-20 cm soil layer, NT and NH treatments were the highest and at 20-50 and 50-80 cm soil layers, NT treatment was the highest with NH treatment being next to it, significantly higher than most of the treatments. The available K contents were the highest with NT treatment at three soil layers. Averagely, NH treatment could maintain higher soil available nitrogen contents during the growing season. Under different water-fertilizer coupling conditions, leaf N, K and Fe contents were the highest with NH treatment and the leaf B level with NT treatment was also significantly higher than the control. Leaf Mn content was the highest with NT treatment and it was also higher with NH than with other treatments. In view of development of pear trees, NH treatment had higher average fruit weight as well as the highest SSC.