638 EXPERIMENTAL FARMS 



7 GEORGE V, A. 1917 



FUETHER EXPERIMENTS WITH ORCHARD HEATERS AND EROST 



PROTECTION. 



Experimental work in frost protection was continued this past season.. The 

 results bear out our former conclusions that orchard heaters are an adequate and 

 reliable protection against frost. This season's work was conducted on a somewhat 

 larger scale than last season's work, a number of different types of heaters being used 

 and experiments being conducted in the orchard as well as in the strawberry patch. 



RESULTS OBTAINED IN THE OUCHARD. 



On the night of May 20, the heaters were lighted only in the young close-planted 

 Wealthy orchard. Sixty-three Competition heaters were used in this experiment, 

 these being distributed over an area of 32,564 square feet. The heaters were, there- 

 fore, used at the rate of eighty per acre. At 1 a.m. an alarm came in that the tem- 

 perature had reached 34 degrees Fahr. and by 1.30, when the heaters were lighted, it 

 had fallen to 32 degrees. The ground temperature that night fell as low as 31 degrees 

 outside the orchard, while the ground temperature inside the orchard was never below 

 34 degrees after the heaters were lighted. At three feet from the ground, the tempera- 

 ture outside was 32 degrees, while inside it never fell below 36 degrees after lighting 

 the heaters. 



On May 27, the heaters were lighted at midnight when the ground temperature 

 was 32 degrees, and 34 degrees was registered three feet above the ground. By 2 

 o'clock the temperature outside stood at 28 degrees on the ground and 32 degrees 

 three feet above the ground, while inside the ground temperature was 33 degrees and 

 the temperature tliree feet above the ground 37 degrees. On this night only forty- 

 two heaters were used at the rate of sixty heaters per acre. ThiS' demonstrated that, 

 in an orchard of one acre area sixty heaters of the Competition type are capable, 

 under certain conditions, of raising the temperature of the air surrounding the trees 

 9 degrees. This rise would not be experienced on an open piece of land without the 

 canopy of trees to act as protection against radiation; in fact it requires twice that 

 number of heaters to cause a smaller rise than 9 degrees. To illustrate the difference 

 between heating an orchard and a groimd crop when the latter is situated in the open, 

 forty-two heaters of the same size and type as the Competition were placed on an 

 area of 15,750 square feet, or in other words, the heaters were distributed at the rate 

 of 120 heaters to the acre. On the night of May 27 these heaters were lighted at the 

 same time the heaters in the orchard were lighted. The minimum ground tempera- 

 ture inside the heated area was 28 degrees for about one-half hour at 2.30 a.m., quickly 

 rising to 32 degrees, the outside temperature remaining at 28 degrees until 4 o'clock. 

 Comparing this with the orchard temperature, it will be recalled that the groimd 

 temperature in that area never fell below 33 degrees, and this with only half the 

 number of heaters per acre. In addition, a note was taken that just outside the 

 heated orchard area the ground was frozen stiff, while inside the area no sign of 

 frost was evident on the ground. Although the ground inside the heated area was 

 not actually frozen in the second case, signs of frost were evident as a result of the 

 half-hour when the temperature went to 28 degrees. The temperature at three feet 

 above the ground was, of course, much higher, it not going below 33 degrees and then 

 only for a shart time, then rapidly rising to 34 degrees. It will be recalled that in 

 the orchard the temperature three feet from the ground did not go below 37 degrees 

 after lighting. This illustrates in an excellent manner, therefore, the difference 

 between heating a ground crop and an orchard. The latter is a comparatively easy 

 and inexpensive operation in comparison with the first. 



On May 28, after the severe frost of the previous night, the strawberry bloom 

 both inside and outside the heated area was counted and notes taken on the per- 



Ottawa. 



