Is the Information We Have on Orchard Fertility of Value in the Nut Grove?

By Prof. F. N. Fagan, Professor of Pomology The Pennsylvania State College

Many of the association members present are also general fruit orchard owners of this state. I am glad to meet with you and must confess that it has been many years since I have had the pleasure of attending the annual meeting of this association. To be exact, the last meeting I attended was the annual meeting held in Lancaster some seven years ago. It is not that the Pennsylvania Agricultural Experiment Station lacks interest in nut culture that keeps it from doing work along nut investigational lines, but because the older and more extensive apple, peach, cherry, grape and berry industries have called upon the resources of the station to its working capacity.

When Mr. Hershey wrote asking me to speak before this meeting I felt that the only information we had at the station that would fit into the picture was the information we have regarding orchard fertility. I therefore gave him the subject, "Is the information we now have on general orchard fertility of value in the nut grove?"

First, let me touch upon some of the papers given this morning. I think it would be well for the nut meat industry to look into the department of health's requirements governing the health inspection of workers handling food products. I also suggest looking into the possibility of the selling of nuts and nut meats by interested high school boys and girls in our many towns and cities.

The question of annual bearing of nut trees is a subject needing investigation. I rather expect we shall find that this factor is closely connected with over-production of a tree one year, fertility and moisture supply, or, in other words, the nuts may be much like apples. While the nature of tree growth may tend to cause trees to be alternate producers, man may upset this natural habit to some extent by proper cultural practices and thus cause the tree to produce, not a full crop in the off year but at least some fruits that will be on the profit side.

As to the toxic effect of some of our nut trees upon growth of other plants growing near by, I rather expect we shall find as time goes on that instead of the trees having a toxic effect they have a robbing effect upon soil moisture and food. One thing that leads me to this belief is that years ago we taught that one reason for seeding a cover crop in the orchard was to have the cover take the moisture from the soil in the fall of the year and in that way check tree growth. We now know that a mature apple or peach tree will reverse this during the growing season and will take its full share of moisture and food from the soil and really take these away from the cover crop. We saw this occur during the dry years of 1929 and 1930 with covers that had been seeded in June. During both these years, in our orchard blocks where the water holding capacity of the soil was low, the cover died over the tree root feeding spaces. Some may have said that the trees were having a toxic effect upon the soil. This was not the case for, in 1932 and 1933, both years of plenty of moisture supply, the covers have grown well around the trees in these blocks.

I shall now ask you to refer to the conclusions on page 3 of our Bulletin No. 294, issued by The Pennsylvania State College, which has just been distributed to you. These conclusions are, of course, based upon our work in an apple orchard but I believe they will apply closely to the management of nut orchards.

Lessons from Fertility Studies in the Experiment Orchard

Most of the experiments in this orchard have now completed 25 years; there have been few changes and these minor ones. Certain lessons may be drawn from this quarter century of research:

1. The fertility of an orchard soil is more than its plant food content. It involves the nature of the soil, its depth and topography, its previous treatment, the use of fertilizers and manures, the amount and nature of the cultivation and the covers or sods grown. Fertilizers are only part of the problem of soil fertility.

2. In this orchard any treatment that has influenced the trees at all has done so in the following order: first, the cover crops; perhaps several years later, leaf color; shortly after, branch growth and circumference increase; and last of all, yield.

3. The reason for this sequence of results is that the treatments, whether chemical fertilizers, manure, or cover crops, have influenced yields chiefly by changing the organic matter content of the soil; that is, those treatments which have resulted in the production of larger cover crops have ultimately resulted in the production of more fruit.

4. The organic content of the soil has been a considerable factor in determining the amount of water in this soil. Those treatments which have built up the organic content have kept the soil in condition to soak up rainfall rather than to lose it by surface run-off. A larger water supply, in turn, has produced more cover crops.

5. The site of this orchard seems nearly level to the casual eye; yet slope, with its accompanying erosion, together with differences in depth of soil, have created nearly as large differences in growth and yield as any treatment. Good treatments have nearly offset the initial disadvantage of poor soil; but it is more economical to plant the orchard on good soil than to attempt the improvement of a poor soil.

6. A short, non-legume sod rotation is an efficient means of building up a depleted orchard soil. After a sod of any kind becomes thick tree growth is checked and yields decline. Orchard sods should be turned under or partially broken, frequently.

7. Moisture conditions often are more favorable in the sod orchard than in the cultivated orchard. Runoff is checked by a sod and less water is used by a sod in mid-summer, after it has been mowed, than by a heavy cover crop.

8. Under a non-legume sod the soil nitrate supply becomes very low in late May or early June, necessitating early applications of nitrogenous fertilizers. Annual applications of 10 pounds of nitrate of soda per tree, or its equivalent in sulphate of ammonia or other forms, have proved profitable in this orchard. Superphosphate, in light applications, has increased sod and cover crop growth.

9. Trees receiving annual tillage with July seeding of cover crops have not done as well as those under sod rotations. If the cover crops are seeded in early June, as has been practiced since 1929, the difference may not be marked.

10. To maintain equal yields, Stayman and Baldwin must make longer branch growth than York.

In addition to these conclusions I will say that any grower who will keep his orchard soil in a state of fertility (by use of manure, proper farm crop fertilizers—nitrate, phosphate or potash alone or in combination with each other—liming and, if necessary, drainage) which will permit growing clovers, alfalfa, soy beans, cow peas, vetch, or any of the legumes, and who really does grow them as covers in his grove or orchard, turning them back into the soil with a minimum period of spring cultivation—just enough to prepare a seed bed—will never need to worry about his soil fertility or water holding capacity.

You note that I say a minimum of cultivation. We taught twenty years ago that cultivation should continue during June, July, and August. We now feel that this teaching was wrong. We can see no benefit from this long summer cultivation but do see some harm. Cultivation during the hot weather of June, July, and August will only aid in burning out the organic matter in the soil, just the very thing we plant a cover for. Many of the covers such as alfalfa, sweet clover and non-legume grasses can be harrowed very heavily in early spring after the frost is out of the ground, thus checking their growth for several weeks, and it is in early spring before the first flowers open, and while open, that the tree needs its nitrogen to aid in the set of fruit, and season's tree growth; the checking of the cover's growth in early spring gives the tree the chance to get its food.

Dr. Zimmerman: I am very grateful for the address of Prof. Fagan.

Dr. Smith: I want to express my appreciation of Prof. Fagan's paper. I want to call to the attention of this convention of people that this young man has actually admitted his hard headedness, that he has been willing to let a tree compel him to change his thinking.