Positioning Temperature Sensors for Frost Protection in Northern Cranberry Production

Vincent Pelletier,Steeve Pepin,Silvio Jose Gumiere,Jacques Gallichand,Jean Caron

doi:10.4236/as.2017.89070

Abstract

Frost can cause serious economic losses in cranberry fields, particularly in northern regions. When the air temperature reaches a low critical threshold, sprinklers are operated to protect vines, to insure crop production and profitability. To avoid frost injury, proper positioning of temperature sensors is critical. A field experiment was designed and conducted to determine the optimal installation height of sensors above soil surface. Temperature data was used to investigate the spatial temperature gradient in the section of a cranberry field. A computer simulation of the temperature profile was performed to simulate the effect of wind velocity on the prediction of air temperature. For optimal use, sensors should be installed at the height of the canopy and several meters away from a dike. On nights with low wind velocities, the canopy air temperature was 2.7°C below that of 500 cm above the ground. The sensors should be put at least five m away from a dike to avoid the transfer of heat from the dike to the sensor. Also, multiple sensors should be installed because of the large variations in air temperature that were measured across the experiment. The simulated temperature indicated that wind velocity strongly influenced the temperature estimation; the effect of the wind on temperatures gradients was greater when the wind velocity was low (<2.3 m/s).

Highlights

The field experiments showed that temperature sensors should be installed at canopy height where the buds are located (~12 cm above ground)
The temperature sensors that were installed 50 cm above ground recorded temperatures that were significantly higher than temperatures at 12 cm on low wind nights, with a maximum difference of 4.4 ̊C
When the sensors were installed close to a dike, the heat from the dike led to higher temperature readings, which could leave unprotected vines further from the dike despite they required frost protection

Summary

Introduction

Cranberries are intensively cultivated in sandy soils, and on cold spring nights, low temperatures may kill buds, flowers and plant tissue depending upon temperature and duration. Buds and flowers are most vulnerable to freeze damage. Frost protection is one of the most important cultural practices in the production of cranberries [4]. Flooding is used for protection from winter frost, sprinklers are typically used in the spring, summer and fall to protect the plants. The critical air temperature threshold to begin irrigation is dependent on the cultivar and on the stage of growth. Protection from frost with sprinklers resulted in a 12% blossom kill compared with 42% in a nonsprinkled area [9]. Frost protection is essential to avoid the damaging effect of cold events [10]

Methods

Results

Conclusion