Most nut growers experience some successes and some failures in the planting of nut trees. A common concept is that there are so many pitfalls in nut growing that when success finally comes it is extremely sweet. The objective of this paper is to bring the sweet taste of victory within the reach of any nut grower who has the desire and the energy to succeed.
Many nut growers find that when trees are transplanted, it takes 1 to 3 years for the trees to re-establish a regular pattern of growth. Sometimes transplanted trees malinger in various degrees and then die. These two patterns can be radically altered by the application of solar heated water to the root zones of transplanted trees. It has long been known that the application of bottom heat to the rooting of cuttings in greenhouses will greatly increase the success rate. The same principle can be applied to trees transplanted in the outdoors.
The technique which I use is simple. One thousand feet of common 3/8" diameter garden hose is laid out on a sunny place on the lawn. Water is flowed through the hose at the rate of ½ U.S. gallon per minute. On sunny days, when the air temperature is 85 degrees F, it is possible to achieve exit water temperatures of up to 105 degrees F. This water is then applied to the newly transplanted trees via a circular trench about 4 inches deep and located at a radius of about 1 ½ feet from the stem of the tree. Approximately 60 U.S. gallons of heated water is applied per tree on about 2 to 3 week intervals during the first growing season. In the early part of the season (mid-May) the soil temperature can be raised from about 50 degrees F to 85 degrees F within a two-hour period. This treatment often converts sulky, malingering trees into rapid growing sorts in as little as 48 hours.
The change can be phenomenal and the first experience with the difference will be quite startling. The difference will be especially noticeable with heat loving trees such as pecan and persimmon. Often these trees do not start to regenerate new roots in the north until the accelerated soil temperatures of late July are reached. Then, when that's the case, it may be too late for the tree to repair itself and to re-establish normal growth before first frost. Consequently, the tree may be lost to "winter damage." Solar heated water can bring the local soil effect of late July into the growing picture as early as mid-May in southern parts of Ontario. The apparent "increase" in the growing season has a dynamic influence on most trees, and the investment made in solar heating equipment will be paid back many times. Furthermore, solar heated water can be used after the trees are well established to accelerate the filling of nuts and to increase tree and nut size.
There are several reasons why solar heated water accelerates tree growth. Biologically, trees function more quickly, i.e., transport fluids at a faster rate as temperatures increase in the 50 degree F to 85 degree F range. Also, most necessary mineral nutrients tend to become more water soluble and available at higher levels of concentration as the soil temperature increases. Therefore, the soil factors are greatly reduced as the limiting parameters of tree growth and the limitations now focus upon air temperatures, sun brightness levels, humidity, carbon dioxide levels, wind velocities, etc. It should be noted that higher levels of fertilization may have to be applied to take full advantage of the accelerated soil moisture and temperature levels.
Some of the many advantages of using solar heated water can be summarized in terms of the following practical achievements in a tree planting at Niagara On The Lake, Ontario:
- Losses in the transplanting of trees have been reduced to less than 2% in the first growing season.
- Trees such as pecan and almond have been brought into quality production within a frost free season of 140-150 days.
- Selected persimmons can produce fully sweet and ripe fruit by the 7th of September.
- Numerous exotic fruit and ornamental trees have been established quickly and the hardiness of these trees has been greatly enhanced, especially in the first winter after planting.
- The production, size, percentage kernel, eating, and storing qualities of nuts can be improved dramatically.
Other growth data is summarized in chart form (Table 1).
| TABLE 1. Tree performance using solar heated water
|
| Species |
Years from planting
to bearing |
Tree height (ft) 10
years from planting |
|
Seedlings |
Grafts |
Seedlings |
Grafts |
| Pecan |
7 |
4 |
20 |
20 |
| Shagbark hickory |
11 |
5 |
15 |
20 |
| Shellbark hickory |
11 |
5 |
18 |
20 |
| Heartnut |
5 |
- |
25 |
- |
| Almond |
4 |
4 |
25 |
15 |
| Hican |
9 |
6 |
20 |
20 |
| Chinese chestnut |
4 |
- |
20 |
- |
| Filbert |
4 |
- |
18 |
- |
| American chestnut |
4 |
- |
20 |
- |
| Scarlet Oak |
7 |
- |
25 |
- |
| Persian Walnut |
6 |
3 |
20 |
-20 |
| Swamp White Oak |
3 |
- |
12 |
- |
| Pawpaw |
5 |
- |
14 |
- |
| Persimmon (virgininia) |
4 |
4 |
16 |
- |
| Black walnut |
- |
4 |
- |
20 |
| Buartnut |
6 |
- |
30 |
- |
| Sweet kernel apricot |
4 |
- |
18 |
- |
| Chinkapin hybrid |
5 |
- |
15 |
- |
|
The foregoing is not an exhaustive listing of all the advantages/performances in the application of solar heated water to root systems, but certainly the trend is clear. Moreover, the following technical details relate to the usefulness of the solar heating f water as an investment:
| Recommended hose diameter |
5/8 inches |
| Recommended hose length |
1000 feet |
| Recommended flow rate |
1/2 U.S. gallon/minute |
| Heat output (air temperature 85 degrees F; source water 60 degrees F) |
22,500 BTU/hour |
| Average thermal efficiency |
50% |
| Equivalent energy value compared to fuel oil |
$1.20 per day [in 1985 dollars] |
| Time to return capital investment |
148 operating days |
| Maximum output water temperature (air temperature 85 degrees F) |
105 degrees F |
| Achievable soil temperatures |
85 degrees to 95 degrees F |
| Area occupied by the solar heater |
250 square feet |
It is simple and easy to harness solar power by means of low technology, low cost equipment, and the sooner you develop a solar heating water system for your grove, the sooner you will be able to share in the sweet taste of success from improved tree performance.
A picture of the solar heater and pictures of tree comparisons are available upon request to sproutnut@aol.com. A self-addressed stamped envelope will be required. Those who are not members of NNGA need to include a $1 fee.
* RR1, Niagara-on-the-Lake Ontario LOS-1J0 Canada
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