WO1987002217A1

WO1987002217A1 - Improved cloche

Info

Publication number: WO1987002217A1
Application number: PCT/GB1986/000632
Authority: WO
Inventors: William Nevil Heaton Johnson
Original assignee: Applied Agricultural Research Limited
Priority date: 1985-10-16
Filing date: 1986-10-16
Publication date: 1987-04-23
Also published as: GB8525497D0; AU6520786A; EP0241528A1

Abstract

Apparatus for use in carrying out horticulture or agriculture in desert or the like areas includes a light-transmitting cover which can be extended over the soil to be cultivated and solar heating means, disposed outside the cover for heating a body of water during the daytime. At night, the heated water is circulated through conduits within the space under the cover to maintain a mild temperature beneath the cover, while said conduits may include exposed channels from which moisture may evaporate to condense on the covering and drop to the soil beneath the covering to water the growing plants. The apparatus may take the form of a vehicle which can be driven out to the selected area, with the light transmitting cover or covers packed or retracted and which, when the selected site has been reached, is stopped and the light transmitting cover or covers extended and the solar heating means displayed.

Description

DESCRIPTION OF INVENTION

Improved cloche

THIS INVENTION relates to apparatus for use in carrying out horticulture or agriculture in desert or the like areas.

There are many desert and the like areas which are not suitable for the cultivation of plants because of the lack of water and /or soil and nutrients which are necessary for promoting and maintaining growth. Water may, in fact, be available near such areas but not in a form suitable for use for irrigating plants for it may contain salt or the like injurious to plant growth.

Furthermore, the climate in many desert areas is characterised by wide diurnal temperature variations with very high temperatures being reached during the day and yet surprisingly low temperatures being reached during the night.

It is among the objects of the present invention to provide apparatus for use in carrying out horticultural or agriculture in desert or the like areas which allows, for example, plants to be reared under conditions of approp¬ riate moisture and at more moderate temperatures than the extremes presented by desert conditions.

According to one aspect of the invention there is provided apparatus for use in carrying out horticulture or agriculture in desert or the like areas, including a light transmitting cover for covering an area of ground to define, with the ground, a substantially closed space, means, disposed outside said space, for heating a body of water by solar energy during daytime and means for circulating water thus heated, during night time, through said space, to maintain a desired temperature therein. Preferably said means for circulating heated water through said space includes conduit means within said space, presenting, at least at selected locations, an opportunity for exposure to the atmosphere of the heated water circulated within said space, thereby to promote evaporation of said water into the atmosphere within said space and its subsequent condensation on the interior of the cover or cloche. Thus, not only can the thermal mass of the water be used to even out the temperature variations within the space, but, even where the water used is salt water or brackish water, such water can be used as a source of pure water to maintain or assist in maintaining the plant life etc. within the space, simply by using the solar energy so readily available in a desert typical environment, without any great technical complexity.

Embodiments of the invention are described below by way of example.

It is preferred that apparatus embodying the invention comprises a central station which can be placed at a selected spot in a desert environment and from which a plurality of cloche-like units can be extended over the ground around the central station or can be retracted back to the central station. Each cloche-like unit, in the extended state, may, in cross section, have the form of a rounded arch or pointed gable and preferably comprises flexible plastics film or sheeting attached at intervals to relat¬ ively rigid frame members, preferably permanently secured to the plastics sheeting so that each cloche takes, for example, the form of a bellows.like structure allowing it to be readily extended and retracted as desired. The apparatus also includes a solar water heater for heating a body of water and which may comprise an array of pipes arranged to be exposed to the sunlight, with means, such as a pump for circulating the water from a reservoir carried in the central station to the solar heater. The solar water heater is also so formed, for example from plastics sheeting, that it can be retracted and stored compactly in the central station. In use, each of the cloche-like units has a water conduit system arranged therein through which water can be circulated by the pump in the central station from the central reservoir therein. During daylight hours, water is circulated from the central reservoir through the solar heater to raise the temperature of said body of water, as a whole. At the same time, if necessary, water from the central reservoir may also be circulated through the conduit system within the cloche units to prevent the temperature within the cloche units from becoming too elevated. The temperature within the cloche-like units may also be prevented from rising too high by making the plastics film or sheeting forming the cloche units semi-reflective, rather than simply transparent, so that a portion of the sunlight striking the cloche units passes therethrough into the interior thereof whilst the remainder is selected therefrom. The desired semi-reflective property may be obtained by splattering the transparent plastics film with an appropriate metal, such as aluminium or in any other appropriate way. The solar heaters may be wholly or partially incorporated on the exterior of the cloche units, the relevant pipes or the like of the solar heater serving in part to intercept the sunlight directed towards the interior of the cloche unit and to utilise sunlight reflected back from the semi- reflective sheeting. During the night, when, typically, ambient temper¬ atures fall dramatically, the water from the central reservoir within the central station is circulated by the pumping means through the conduit systems within the cloche units so that the heat stored in the heated water is now used to maintain a desired night time temperature within the cloche units. In this way, it is possible to ensure that the daytime temperature within the cloche unit does not rise above a preselected level suitable for the cultivation of the particular plants being grown and that, at night time, the temperature does not fall to levels such as would damage or inhibit the growth of such plants.

Preferably at least portions of the water conduit system within each cloche unit are so formed as to expose the heated water to the atmosphere within the cloche unit. The plastics film forming the walls of each cloche unit are exposed on the exterior of the cloche unit to the low ambient night temperature and are thus relatively cold whilst the air within the cloche units is kept relatively moist and warm by the circulated warm water. Consequently there is a continual condensation of moisture on the internal surfaces of the cloche units. The cloche units are so formed that this water either runs down the sides of each cloche unit into the soil below the cloche unit or drips from formations provided in the interior of the cloche unit on to said soil, that effectively providing, during the night hours, an artificial rain within each cloche unit. To allow exposure of the heated water within the cloche unit to the atmosphere therein, sections of the conduit system within each cloche unit, or substantially the whole of the conduit system within each cloche unit, may be in the form of an open trough or channel. Alternatively, such conduit systems or sections thereof may be formed of permeable material, for example of plastics sheeting formed with minute holes, or so formed as to be vapour permeable but impermeable to liquid water, so that some of the water from within the conduit system can evaporate into the atmosphere within the cloche unit to condense in the manner indicated.

Preferably the conduit system within each cloche unit and the conduit system outside each cloche unit associated with the solar heater or respective part thereof are formed of flexible plastics film so that the whole may be folded up or extended as a unit without the need to separately erect or dismantle different parts of the system.

The central station may take the form, for example, of a self- propelled vehicle which, after the central water reservoir therein has been filled with water from the available water supply, which may be sea water or brackish water, and with the cloche units and solar heaters retracted, may be driven out to a selected location in the desert, and thereafter the cloche units extended and the solar water heaters deployed, for example after appropriate tilling of the respective areas for desert soil and the planting of the diurnal seeds or plants.

Alternatively the control station may be a substantially permanent structure erected at the desired location. Each cloche unit preferably includes an appropriate temperature sensor or sensors and the central station preferably carries a computer controlling the pumping means in response to the sensor temperatures, as well as in response to sensors indicative of time of day, insolation etc., the computer also controlling valve means which determines whether the pumping means circulates water from the central reservoir through the solar heater or through the conduit systems within the cloche units or through both and in what proportion, the whole operating so as to secure a predetermined pattern of diurnal temper¬ ature variation which will normally be substantially less extreme than that obtained outside. The central unit may also, incorporate, of course, apparatus for harvesting the plants grown and treating the same, etc.

On the central station, a structure carrying the cloche unit may be mounted for rotation about a central vertical axis, from which the cloche units radiate outwardly, whereby the location of the cloche units over the ground surface may be displaced angularly from time to time in accordance with the crop cycle of the plants concerned, allowing, for example, areas of earth to be exposed for tilling, application of dry fertilizer and the like tasks not requiring a controlled environment, with the respective cloche units being moved over the areas so treated, in time for the next crop cycle, leaving the areas on which crops were previously grown exposed for retilling and refertilization.

Whilst reference has been made to cloche units, it will be appreciated that there is no theoretical restriction to the possible size of these and the units may, for example be made sufficiently large to accommodate livestock and personnel and may, for example, accommodate walkways for personnel employed to tend the plants or livestock within the cloche units.

Claims

CLAIMS:

1. Apparatus for use in a carrying out horticulture or agriculture in desert or the like areas including a light transmitting cover for covering an area of ground to define, with the ground, a substantially closed space, - means, disposed outside said space, for heating a body of water by solar energy during daytime and means for circulating water thus heated, during night time, through said space, to maintain a desired temperature therein.

2. Apparatus according to claim 1 wherein said means for circulating heated water through said space including conduit means within said space, presenting at least at selected locations, an opportunity for exposure of the heated water circulated to the atmosphere within said space, thereby to promote evaporation of said water into the atmosphere within said space and its subsequent condensation on the interior of the cover or cloche.

3. Apparatus according to claim 2 wherein said conduit means includes at least parts, within said space, formed as open troughs or channels for exposure of the heated water to the atmosphere within said space.

4. Apparatus according to claim 2 wherein said conduit means includes at least parts, within said space, formed with perforations or pores suffic¬ iently restricted to ensure that the rate of seepage of water therethrough is not greater than the rate of evaporation of water from said perforated or porous parts of the conduit means.

5. Apparatus according to claim 2 wherein circulation of the heated water within said space is under control of a computer to maintain a desired night temperature within said space.

6. Apparatus according to claim 2 wherein the interior surface of said cover is formed to promote condensation of moisture from the atmosphere in said space, and the dripping of the condensed moisture onto the soil below.

7. Apparatus according to any preceding claim, which includes a central station and a plurality of elongate cloche-like units extending from said central stations, said cloche-like units being so formed as to allow them to be extended from or retracted towards the central station.

8. Apparatus according to claim 7 wherein said cloche-like units com- prise flexible plastics sheet material.

9. Apparatus according to claim 8 wherein said plastics sheet material has been rendered semi-light transmissive and semi reflective, for example by spluttering with metal.