JPH0556930B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention mainly relates to a method for preventing frost damage in tea gardens, but it can also be applied to other agricultural products in general.

[Prior Art] As a frost prevention measure in tea plantations, it is already well known that tea leaves are temporarily frozen by sprinkling water to avoid damage caused by frost.

[Problem to be solved by the invention] In a method in which a large number of sprinklers are installed in a tea garden and the tea leaves are frozen by uniformly sprinkling water within a certain period of time, it is difficult to water the tea leaves all at once. As a general rule, it is essential to secure a considerable amount of water for this purpose, but tea plantations are usually located in regions with relatively poor water, such as plateaus or mountainous areas, and therefore the above-mentioned irrigation water supply is essential. was difficult.

Therefore, intermittent water spraying has been considered effective for saving water, but in this case, if the intermittent spraying is not performed within at least 2 minutes, the sprinkler nozzle will freeze and become clogged. Furthermore, while water hammer occurs due to interruptions in water supply, it is common for tea plantations to have differences in ground height, so when watering is stopped, water leaks from sprinklers in lowlands and spreads to higher ground. There was a problem in that air pockets were created in the water pipes, which promoted the water hammer effect, and at the same time, the discharge of the accumulated air caused water leakage on the high ground side, making the water spray uneven.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention divides the area of a tea garden into approximately two halves and installs an appropriate number of sprinklers in each tea garden. Two systems of water distribution pipes are installed that branch to the tea plantation, and the valves that open and close each water pipe are linked so that they open and close at the same time and in opposite directions, thereby canceling out the internal pressure of the valves as much as possible. In addition to preventing water hammer, by watering the tea plantations alternately for up to 2 minutes, and by making the opening/closing valve also function as a constant pressure release valve, air pockets in the water pipes can be avoided, and the above-mentioned This eliminates the problem and always performs proper and smooth watering to prevent frost damage to tea leaves.

Examples will be described in detail below.

[Example] Experimental example 1 Experimental location in 1978 Ibushi Tea Farm, Eiga-cho, Kagoshima Prefecture Tea plantation Area: 50a, altitude: 35m Facility: 20L ₂ -nozzle sprinkler Diameter: φ2.4mm Water pressure: 2.8Kg/cm ² Water volume: 6.2/min Watering diameter: 22m Arrangement interval 10m x 12m Watering intensity 3.1mm/hr Minimum temperature on tea plant surface -4.5C Wind speed 0.1m/sec Water temperature 18C Watering time 7 hours 10 minutes As a result, the leaf surface became frozen and the icicles decreased, but the ice thawed It was found that as the process progressed, it had an anti-frost effect.

Example 2 For a 1.5ha tea garden, the watering amount is only equivalent to 0.5ha, so as shown in Figure 1, it is divided into three sections of 0.5ha each and divided into A, B, and C sections. Intermittent watering was performed alternately between the ward and the ward.

In other words, the lowest temperature on the tea plant surface -4C Wind speed 0.1m/sec Water temperature 18C Watering time 9 hours 10 minutes (10:50 PM - 8:00 AM) During this time, the electric butterfly valve with a timer set at 1 minute 40 seconds intervals was used to perform A Water was sprinkled alternately in Ward and B Ward. At this time, the water droplets scattered in the air increase the nearby temperature by exchanging heat with the air before falling, and the water droplets adhering to the leaf surface freeze and release thermal energy, completely eliminating frost damage. could be prevented.

Furthermore, in this example, as shown in the second diagram, section C, which is located at a high level adjacent to watering sections A and B, was also not damaged by frost. This is thought to be due to the convection of humid air warmed by heat exchange, which caused an updraft to rise, causing the temperature to rise even in section C, which is located at a higher elevation.As a result, the frost protection effect on an area of 1.5 ha That's what I got.

[Function] In the above-mentioned embodiment, the water pipes branched into the A section and the B section have timers set in advance to open/close valves that act in opposite directions to each other, and are operated simultaneously. As shown in the figure, the flow rate is gradually restricted by closing one valve closing operation a, but the flow rate is gradually opened to a larger value by the other valve opening operation b, resulting in a composite flow rate of C, which is approximately A minimum flow rate of 75% was to be ensured.

Therefore, if it is configured to have two water distribution pipes and a simultaneous opening/closing valve (electric butterfly valve),
Water hammer can be easily prevented.

Furthermore, in order to prevent water leakage in low places, it is sufficient to configure each on-off valve so that it is always closed under a constant pressure. Fig. 4 shows an example of this. Enter from inlet 1 as shown in
A spring 4 closes the valve body 3 that closes the center hole of the valve seat 2.
A piston 5 is connected to the valve body 3 via a rod 6, and the closing pressure of the valve body 3 is adjusted by adjusting the knob 7 to adjust the elasticity of the spring 4. The system is designed to automatically allow water to flow if the liquid pressure becomes greater than the closing pressure.

Therefore, water is automatically supplied in response to pressure drops due to water leaks in water pipes at low locations, preventing air pockets, and, in conjunction with the above-mentioned on-off valve for dual-line water pipes, ensures smooth intermittent water dispersion. It has now become possible to implement the following.

[Effects of the invention] In addition to the above-mentioned experiments, a number of other experiments have shown that the water savings of intermittent watering compared to continuous watering was 50%, and the cost reduction was considerable, compared to conventional intermittent watering. The icing of sprinklers that occurs is prevented by controlling the intermittent operation within at least 2 minutes, and the water hammer caused by the intermittent operation is avoided by the valve action that opens and closes two lines of piping at the same time. The release valve prevents the formation of air pockets in the piping and enables smooth intermittent sprinkling of water, and its effectiveness is extremely significant.

Furthermore, although the above-mentioned embodiments have been described with respect to tea gardens, they are also effective for preventing frost damage to all other agricultural crops, and it goes without saying that the present invention is not limited to tea gardens.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an example of partitioning a tea garden according to the method of the present invention, FIG. 2 is a vertical cross-sectional view of the tea garden,
Figure 3 is an electric butterfly valve flow characteristic diagram, Figure 4
The figure is a partially cutaway front view showing an example of a constant pressure release valve. a - Valve closing operation curve, b - Valve opening operation curve, c - composite flow rate curve.

Claims (1)

[Scope of Claims] 1. Divide the area of a tea garden into two, install a large number of sprinklers at appropriate intervals in each tea garden, and provide two systems of water distribution pipes for branching water supply to the tea garden, and the water distribution pipe A method for preventing frost damage in tea gardens, etc., by opening and closing valves that open and close at the same time and in opposite directions to alternately sprinkle water on the tea garden divided into two halves. 2 The above-mentioned intermittent water spray intensity is approximately 1.5 mm per unit time.
2. The method for preventing frost damage in tea gardens, etc. according to claim 1, wherein 3. The method for preventing frost damage in tea gardens, etc. according to claim 2, wherein the intermittent time of the intermittent sprinkling is at least 2 minutes. 4. The method for preventing frost damage in tea gardens, etc. according to claim 3, wherein the valve for opening and closing the water pipe is a constant pressure opening type valve.