You can put one cup of fertilizer in the best period for growing. More often, June is the most proper time for you to fertilize the pecan trees. April or May is also very proper for fertilizing. You should pay attention to the trunk when you put the fertilizer below the branches. Nitrogen fertilizers are much better and you can get them from the local stores. For the next year, you should also do this in the same way. However, you should add more fertilizer in the third year.For the mature trees, you should give more fertilizer to them. More often, the older the trees are, the more fertilizer they will need. If the trees are more than five years old, you could put four cups. And if they are more than seven years old, you should spread two cups under the trunk for each inch. You may need to apply the fertilizer for several times in a year. Late March, late May and early June are also the best time to apply fertilizer.
For the pecan trees which are deficient in zinc, you should be more careful in choosing the fertilizer. You may check the soil PH first and then choose the most suitable for the trees. If you have found that the PH level is higher than 7.0, you should try to make the PH level maintain at 7.0 or so. Then, you should apply a small amount of zinc for the first year after you planting the trees. You must do this frequently so that the trees will be able to have enough zinc to grow better. You should follow the instruction of the manufacture when you apply the zinc and choose the best time to do it. For the mature trees, you should apply zinc the time before the bud turns into leaf.