RU2146442C1 - Method for subsurface irrigation of plants grown in protected ground in trays - Google Patents

Abstract

FIELD: agriculture. SUBSTANCE: method involves supplying water into lower part of tray containing small-sized gravel material arranged in horizontal plane and covered with perforated film; placing substrate onto perforated film; positioning level sensor in tray for regulating water penetration depth; controlling moisture content of substrate by means of moisture content sensor. EFFECT: increased efficiency by uniform moistening of ground and simplified irrigation process. 1 dwg

Description

 The invention relates to the field of agriculture, in particular to the field of growing plants in greenhouses.

 Known subsurface watering of plants, which is deservedly considered one of the most effective methods of watering agricultural crops [1]. In this case, the most widespread irrigation system using tubular humidifiers (conduits) in the form of pipes or hoses laid at a certain depth in the soil, having outlet openings (outlets) for supplying water to the soil. However, with subsoil irrigation it is difficult to ensure a uniform distribution of moisture in the soil. Therefore, in order to more evenly absorb moisture into the soil, ⌀ pipes (conduits) and holes in them are calibrated along the length of the pipelines based on hydraulic calculation. However, it is difficult and expensive. The holes become clogged over time, and the results are poor. Instead of calibrating the water conduit and the openings in them for the same purpose (for more even distribution of water), various regulators are used to stabilize the pressure at the outlet of the water conduit [2].

 At the same time, irrigation is not automatic, but based on the irrigation rate calculated according to the available formulas, since the uniform distribution of moisture on the irrigated surface necessary for automation of irrigation cannot be achieved.

 To reduce the cost of the system of subsoil irrigation and make it more reliable, and most importantly, to increase the uniformity of moistening (never achieved yet!), Channel water distributors filled with rocky fractions are used [3]. The channel bottom (for waterproofing) is covered with a film, a rocky layer is laid on it, a perforated film is laid on it, a sand (buffer) layer is poured on top and then the soil substrate.

 As follows from the description of this method [3], water that flows immediately through both porous materials is distributed more evenly into the soil through the buffer layer. Such a system is more reliable, because does not clog for a long time. However, this method also does not allow to obtain such uniformity of soil moisture so that it becomes possible to automate this irrigation process. And we apply this method [3] for open field farming, because this system is flow-through, which complicates its use in sheltered soil. Soil irrigation has practically no application in protected soil farming [4], despite the fact that its use in sheltered soil creates favorable conditions for increasing productivity, reducing plant morbidity, reducing water consumption for plant irrigation, etc. [1].

 The aim of the invention is to obtain a cheap method of subsoil irrigation in protected soil installations, which allows for almost absolute uniformity of soil moisture and the ability to automate the process of subsoil irrigation in the simplest way. We managed to achieve this goal in the protected ground using and somewhat transforming a technique similar to the prototype [3].

 To do this, finely granular, slightly wettable material (coarse sand, expanded clay, pebbles) is laid on the bottom of the sealed shelving or ditch, lined and shaded with film, the surface of which is then leveled strictly horizontally. On top of such a granular layer (conduit) is covered with a polyethylene film with perforation uniformly made over its entire surface. On this film, as in the prototype, you can put a sand "buffer". However, this is not necessary if a material with good capillary properties is used as a soil substrate (for example, just sand of a certain fraction, which is applicable when irrigation is carried out with a nutrient solution). If water is then slowly fed into the water conduit zone, its level will rise over the entire water conduit area strictly horizontally. At some point, the water reaches the level of the film (and the buffer or substrate on it), and touches them strictly simultaneously over the entire irrigation area. And then, the water will already through the perforation exactly the same and evenly flow into the substrate. The level of water rise and its penetration into the substrate is monitored, regulated and limited by a water level sensor. When the water rises in the substrate to a predetermined level, the water supply stops. After this, the rise of moisture into the soil and its moisture occur already due to capillary forces. After the supplied portion of moisture goes into the substrate, the water level will drop below a predetermined one, and the water supply will automatically be repeated. Watering will be repeated until the soil moisture, controlled by the appropriate sensor at the desired level, reaches the set value.

 Since planting of plants on this irrigation area is assumed to be uniform, the absorption of moisture from the substrate will be the same everywhere. Thus, the humidity of the substrate at any point of irrigation will always be the same. This means that automating the process of subsoil irrigation will be quite simple.

 If instead of using an earthen substrate, sand of the appropriate fraction is used, and a nutrient solution is applied under the roots of the plants, we get a kind of hydroponics.

 The advantage of hydroponic plant cultivation is well known.

 The proposed method (in the mock version) was tested in the greenhouse of the All-Russian Institute of Plant Production named after N.I. Vavilova (see drawing).

 Here, in one of the concrete sealed racks 1, in which plants 2 are grown, a relatively thin layer of expanded clay of fine fraction 3 - “water conduit” was poured. The expanded clay surface was leveled strictly horizontally, and a polyethylene film 4 with a perforation 5 uniformly applied to its surface was laid on a leveled layer. A thin layer of sand 6 was poured on the film — the “buffer”, and already on the buffer — earthen substrate 7. When grown in the experiment lettuce 2 layer of earthen substrate 7 was 30 cm. From the tank 8 through e. valve 9 through the pipe 10 in the zone of the conduit 3 is supplied with water. When you turn on the control unit 11, the signal from the level sensor 12 of the flow of water into the buffer zone 6 opens e. valve 9. After that, the level of water entering through the pipe 10 into the water conduit 3 will slowly rise in it, while maintaining a strictly horizontal surface.

 At some point in time, the water simultaneously touches the film 4 over its entire area, passes through the perforation 5 into the buffer layer 6.

 After the water reaches the height set by the level sensor 12, the valve 9 is turned off and the water supply is temporarily interrupted.

 But the moisture entering the buffer 6 begins to be absorbed (absorbed) through the capillaries into the sand, which leads to a decrease in its level and the repeated activation of valve 9 through the sensor 12. Thus, the water will gradually be absorbed into the soil, rising higher and higher, while the humidity sensor soil 13 does not give a signal about the achievement of soil moisture (at the level of its installation) to a predetermined value. Now email. the valve 9 is turned off by the sensor 13. After a decrease in soil moisture, due to its evaporation and transpiration of moisture by plants, the process will be repeated again.

 An experiment conducted in the VIR experiment on a pilot plant for growing lettuce (as a precocious crop) with automatic subsoil watering showed its operability, simplicity, and reliability at low cost. Productivity has increased significantly.

 The taste qualities of the grown products improved. Water costs decreased. No diseases of lettuce were noticed, which (like many other crops) does not tolerate irrigation by sprinkling.

Information used
1. "Intrasoil irrigation of agricultural crops." Tutorial. Krasnodar city. 1988 year

 2. Auth. St. N 812238, CL A 01 G 25/06.

 3. Auth. St. N 1613060, CL A 01 G 25/06.

 4. E. Aliev, N. Smirnov "Technology of cultivation of vegetable crops in greenhouses". Agropromizdat. 1987, p. 74.

Claims (1)

 The method of subsoil watering plants when growing them in closed ground in trays, comprising supplying water to the lower part of the tray, separated from the substrate by a perforated film, and stopping its supply when a sufficient level is achieved, characterized in that a thin layer of fine gravel material is laid on the bottom of the tray, surface which is aligned strictly horizontally, after which it is covered with a perforated film, the depth of penetration of water into the substrate is limited by a level sensor installed in the tray, and awn substrate control and limit the humidity sensor also.