Plant husbandry – Receptacle for growing medium – Irrigator
Reexamination Certificate
1998-05-08
2001-01-30
Carone, Michael J. (Department: 3643)
Plant husbandry
Receptacle for growing medium
Irrigator
Reexamination Certificate
active
06178691
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a capillary carpet irrigation system which includes a water bearing capillary carpet disposed on a supporting surface and a plurality of water permeable pots resting upon and in hydraulic connection with the carpet. The pots contain growing medium and roots of plants. Conventional irrigation equipment supplies water to the carpet. A four layer capillary carpet includes: a water impermeable base membrane of polyethylene; and a water permeable mnicroperforated dark coloured top membrane. Between the top and bass membranes two water bearing capillary mats are supplied with water from the irrigation equipment. The base membrane prevents water seepage into the underlying soil substrate. The microperforated top membrane permits passage of water into the carpet while inhibiting evaporation and weed growth. The dark colour also inhibits algae growth in the mats. The fine pore rigid capillary mat is disposed upon the base membrane and is capable of receiving water from the irrigation equipment. The rigid mat is relatively stiff and can retain a selected hydraulic transmissivity while supporting the weight of the pots. A resilient coarse pore capillary mat in disposed upon the rigid mat and beneath the top membrane. The compressible mat is resiliently compressible locally under each pot thus defining a plurality of localized Capillary action conduits between the rigid mat and each water permeable pot through the permeable top membrane. The resilient coarse mat when uncompressed has a negligible capillary rise and serves to inhibit evaporative water loss from the underlying rigid mat. The resilient coarse mat impedes air circulation immediately above the upper surface of water held in the water bearing rigid mat. The air within the compressible mat pores immediately above the rigid mat therefore have a high humidity. Air circulation within the compressible mat is impeded by the inherent resistance of the porous structure. Thus, water vapour escape from the water surface in the rigid mat through the perforations of the top membrane is impeded reducing evaporative water loss. To impede root growth from the pots into the top membrane and porous mats, a root growth biobarrier is disposed within each pot.
The invention relates to a capillary carpet irrigation system which includes a water bearing capillary carpet disposed on a supporting surface and a plurality of water permeable pots resting upon and in hydraulic connection with the carpet. The pots contain growing medium and roots of plants. Conventional irrigation equipment supplies water to the carpet A four layer capillary carpet includes: a water impermeable base membrane of polyethylene; and a water permeable microperforated dark coloured top membrane. Between the top and base membranes two water bearing capillary mats are supplied with water from the irrigation equipment. The base membrane prevents water seepage into the underlying soil substrate. The microperforated top membrane permits passage of water into the carpet while inhibiting evaporation and weed growth. The dark colour also inhibits algae growth in the mats. The fine pore rigid capillary mat is disposed upon the base membrane and is capable of receiving water from the irrigation equipment. The rigid mat is relatively stiff and can retain a selected hydraulic transmissivity while supporting the weight of the pots. A resilient coarse pore capillary mat is disposed upon the rigid mat and beneath the top membrane. The compressible mat is resiliently compressible locally under each pot thus defining a plurality of localized capillary action conduits between the rigid mat and each water permeable pot through the permeable top membrane. The resilient coarse mat when uncompressed has a negligible capillary rise and serves to inhibit evaporative water loss from the underlying rigid mat. The pores of the compressible mat impede air circulation immediately above the upper surface of water held in the water bearing rigid mat. The air within the compressible mat pores immediately above the rigid mat therefore have a high humidity. Air circulation within the compressible mat is impeded by the inherent resistance of the porous structure. Thus, water vapour escape from the water surface in the rigid mat through the perforations of the top membrane is impeded reducing evaporative water loss. To impede root growth from the pots into the top membrane and porous mats, a root growth biobarrier is disposed within each pot.
TECHNICAL FIELD
The invention is directed to a novel four layer irrigation carpet, including an impervious base membrane, and a permeable top membrane enveloping a rigid water bearing rigid porous mat and an overlying resilient compressible coarse porous mat, wherein the compressible mat when uncompressed serves as a mulch to inhibit water evaporation and when compressed (under the weight of pots placed upon the carpet) conducts water under capillary action from the rigid mat to the water permeable pots.
BACKGROUND OF THE ART
Large quantities of water and fertilizers are used during irrigation in nursery operations and other horticultural applications where trees and plants are grown in containers. Since the containers hold a limited volume of growing medium, there is a frequent need for watering and fertilizer supply. In the case of water demand, the containers lose water through evapotranspiration, not only from the soil's surface but also through the sides of the containers. In order to enable easy transport of the containers and plants therein, it is highly desirable to keep the volume of growing medium to a minimum, however, at the increased risk of dehydration and with a high demand on the growing medium to supply nutrients to the growing plants.
Overhead sprinkling irrigation is the method most frequently used in Canada and the United States for watering such plants and distributing dissolved fertilizers. The overhead sprinkler technique is not particularly efficient in terms of water use however, and studies have reported losses of up to 90% of the volume of water used. Part of this water loss is from evaporation and part from surface runoff. As a result of evaporation, dissolved compounds such as salt, nutrients, calcium, etc. gradually deposit upon the irrigated surfaces. Irrigation water is also lost through runoff and represents a contamination risk for the soil surface and groundwater. Runoff water contains fertilizers, nutrients, biosides and granular herbicides which are leached from the soil substrate.
In recognition of this problem, regulations have been adopted or are impending in a number of North American or European jurisdiction. The intent of the regulations is to require closed circuit irrigation and fertilization systems with no runoff permitted. A closed system would require recovery and recirculation of water and nutrients, however, at present there are few cost effective options available to nursery producers. A closed system would require installation of water catchment and treatment systems involving holding tanks and filtration systems, together with rigorous monitoring of water quality to regulate the accumulation of salts and contaminants.
Micro-irrigation systems provide another alternative, however, they do not necessary eliminate all runoff due to leaching from the bottom of the containers, Micro-irrigation however, does have the advantage of significantly reducing the volumes of water used. Due to the high installation costs however, micro-irrigation is an expensive alternative and requires strict control on water quality to avoid plugging of the conduits and other components of the system. In addition, micro-irrigation systems are best suited for uniform arrays of similar plants and are not flexible in respect of placement and size of containers used. For these reasons, the application of micro-irrigation has been restricted to production of large trees in containers with a volume greater than 20 liters. Micro-irrigation therefore cannot be considered as a general solution to the proble
Caron Jean
Tardif Pierre
Carone Michael J.
Mitchell Robert
Nguyen Son T.
Swabey Ogilvy Renault
Universit{acute over (e)} Laval
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