AU2021105643A4 - Use of a Spatial Electric Field for Improved Plant Growth, Biomass Yield and Soil Moisture Retention - Google Patents

Abstract

The invention relates to an electrically driven method that comprises an earth grounded main high-voltage (HV) DC generator with a control box, insulator and electrode wire installed either in a farm field, over vegetation or a planted crop, or in greenhouses. The key factor that drives the enhancement of plant growth, biomass yield and soil moisture retention is the spatial electric field that regulates the dynamic processes in plant growth and development by the changes in the electric field intensity that also generates small amounts of electrical current in the soil, that promote favourable effects such as decreased evaporation rate, retention of moisture in soil and increased nourishment of plants leading to increased crop yields. The invention, with its versatility, have an impact on sustainable farming and agriculture by positively addressing the issue on the global effort to food security through high yield, high quality and safe food to every community. Moreover, utilization of the invention allows farming without the use pesticides and chemical fertilizers that are detrimental to life and the environment as well as economy in the use of irrigation water for plants and crops. Many areas of the world, e.g., arid, semi arid regions and some tropical zones, are experiencing significant depletion of water supply for irrigation affecting the production and supply of water in both developed and developing nations. 1/13 Lfl Lfl + M IV> + CnJCN ry) r'4$ r' +4 r4'

Description

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Use of a Spatial Electric Field for Improved Plant Growth, Biomass Yield and Soil Moisture Retention

FIELD OF THE INVENTION

[0001] The present invention relates to enhancing plant growth, and in particular the use of SEF (Spatial Electric Fields) to improve plant growth, biomass yield and soil moisture retention.

BACKGROUND TO THE INVENTION

[0002] The global support for sustainable farming and agriculture has been gaining popularity because of the increasing demand for food and the slow progress in the scaling up of food production facilities. In the late 2 0 th century,thecallsforthebanningof pesticides, insecticides as well as chemical fertilizers intensified, gearing the attention of agricultural research to natural methods of food production by plants and crops [Davis, F. (2014). Roads Taken. In Banned: A History of Pesticides and the Science of Toxicology (pp. 214-220). Yale University Press.]. Several methods have been introduced and adopted to address the problems associated with the use of toxic agricultural chemicals and insecticides for food processing - one particular sustainable method is the use of electricity to enhance plant growth, namely "electroculture".

[0003] The use of electricity in stimulating plant growth was discussed in several research papers as early as the 1 8 th century, when a Scottishscientist Dr. L. Maimbray electrified two myrtles during the month of October in 1746 and found out that the electrified myrtles put forth more small branches, with longer stems and even blossomed earlier while no such early development and enhancement was observed in the non electrified myrtles. Several crop experiments using electricity to affect plant growth followed some of which have related studies on the electrical state of the atmosphere and regional temperature variations with the majority obtaining significant improvements in both plant growth and yield.

[0004] One example is the use of electrodes to apply electrical current to the plant root system, which was done in experiments to determine the effect of electric current on certain crop plants by Iowa State College of Agriculture and Mechanic Arts from the early 1930s to the late 1940s. The experiments involved the use of copper-zinc strips as electrodes buried in the middle of the flats with oats inside a greenhouse. The use of variable applied potentials of between 7kV - 20kV more than doubled the crop yields when applied as intermittent current of 10 - 15 minutes per day whilst maintaining the currents at 0.5 mA to 3 mA [Dorchester, D.S. (1937). The effect of electric current on certain crop plants. Research Bulletin No. 210 (pp. 1-37) Iowa State College of Agriculture and Mechanic Arts]. The experiments also proved that in the applied current range, there are no significant differences in the amount and growth rate of microorganisms, nitrogen and carbon dioxide content of the soil, proving further that electrical stimulation mainly targets the root system of the plants.

[0005] In a more recent electroculture study undertaken in the Philippines, an increase in crop production was achieved using a solar panel as power source in a backyard garden with the current applied to the soil using nails connected to a solar panel, resulting in the enhanced growth of the crops proximate to the current path [Reyes, E.M., Achico, G.M. (2019). Solar-powered electroculture technique for backyard farming, International Journal of Advanced Research and Publication 3(3), 116-121.1.

[0006] In an experiment with mushrooms, Tsukamoto et al. reported that the application of impulse type electrical signals at high voltage levels and short period of time stimulated the growth of several types of mushrooms. [Tsukamoto, S., Kudoh, H., Shizuki, K., Ohga, S., Yamamoto, K. and Akiyama, H. (2005). Development of an automatic electrical stimulator for mushroom sawdust bottle. 15th IEEE Pulsed Power Conference,1437-1440.], while Jamil et al. added that the application of the right amount of electricity or electric energy increase the yield of mushroom up to 100% [Jamil, N.A.M., Gomes, C., Kuen, C.P., Ab Kadir, M.Z.A., Gomes, S. (2018). Electrical Stimulation for the growth of plants: with special attention to the effects of nearby lightning on mushrooms, Asian Jr. of Microbiol. Biotech. Envi. Sc. 20(4), pp. 1332-1343]. On the other hand, Takaki et al. mentioned that the application of controlled high voltage impulses to the cultivation systems of several crops such as tomatoes, lettuce, strawberries and even some flowers has improved the yield [Takaki, K., Yamaguchi, R., Kusaka, T., Kofujita, H., Takahashi, K., Sakamoto, Y., Narimatsu, M. and Nagane, K. (2010). Effects of pulse voltage stimulation on fruit body formation in Lentinula edodes cultivation. International Journal of Plasma EnvironmentalScience & Technology. 4 (2), pp. 108-112.]. The study of Wang et al, in addition, indicated that the effect of high voltage electric field (HVEF) was identified through the assessment of the plant activity index of aged rice seeds. The application of the HVEF significantly increased activity index of the aged rice plant by increasing the levels of superoxide dismutase (SOD), peroxidase (POD) and catalase

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(CAT) - enzymes that govern plant growth and maturity. In addition, a decrease in the leakage conductivity and the malondialdehyde (MDA) content was also observed during the application of the HVEF [Wang, G., Huang, J., Gao, W., Lu, J., Liao, R., Jaleel, C.A. (2009). The effect of high-voltage electrostatic field (HVEF) on aged rice (Oryza sativa L.) seeds vigor and lipid peroxidation of seedlings, Journal of Electrostatics 67(5), pp. 759 764.].

[0007] In China, almost 30 years ago, one of the pioneers of electroculture, Dr. Liu began developing what he refers to as the "space electric field" method to enhance plant growth. He stated that there is usually a natural vertical electric potential gradient in the air of about 100 volts per meter. Liu began setting up experiments in greenhouses where the potential was increased to between 700 volts and 20,000 volts per meter. Electrical wires were placed above the crops and the electric field was generated from these wires via the atmosphere to the crops. Significant improvements in crop yields were observed and within a few years, electroculture greenhouses were established up in Beijing, Dalian and Tianjin. In a separate experiment of Liu and his team, the application of the high voltage electricity, without reference to the polarity of the electricity, applied to pepper, green pineapple tree and golden diamond tree plants, improved the photosynthetic process in the plants by promoting the CO 2 absorption rate of the plants during the process [Shiqui, Z., Linxue, Z., Zhou, C., Yan, X., Mengdi, W., Jianhe, Y., Liu, B. (2016). Laboratory test on effects of high voltage electricity on electrostatic properties and promoting photosynthesis of plants, Journal of Agricultural Engineering, 32(17), pp. 168 173]. According to Liu et al, the high voltage electric field's corona discharge ionizes the air that primarily contains nitrogen and oxygen, speeding up the rate of formation of nitrogen dioxide which is soluble in water. When this nitrogen oxide was absorbed by the soil and the plants with an abundance of hydrogen ions produced from the action of the positive electric field ammonia (NH 4), an important component for plant growth, is formed releasing more oxygen in the plant root system and the soil. This was supported by the study of Li et al. stating that high voltage electric fields could improve the dynamic absorption of NH 4+ and N03- in hydroponically grown tomatoes [Li., M., Wu, Y., Zhang, M., Zhu, J. (2018). High-voltage electrostatic fields increase nitrogen uptake and improve growth of tomato seedlings. Can. J. Plant Sci. 98, pp. 93-106].

[0008] In the process of electroculture, the electric field applied impacts the soil moisture content. Resnikov and Salazar [Reskinov, M., Salazar, M. Further progress in electrostatic nucleation of water vapor. Proc. 2016 Electrostatics Joint Conference, 1-9 (2016)] in their study mentioned that charges in the water vapor molecules termed as "electrohydrodymamic or EHD flow" is influenced by an electric field and electrostatic enhancement of condensation is achieved based on several factors, one of which is the EHD flow of the water vapor due to the drag by electrically charged droplets of water. Other studies like that of Wang et al. claims that the application of electric field onto the soil is affects the surface wettability of the soil by altering the individual molecular droplets of water vapor to increase surface tension [Wang, Q., Xie, H., Hu, Z., Liu, C. The impact of the electric field on the surface condensation of water vapor: Insight from molecular dynamics solution. Nanomaterials 9(64), 1-13 (2018)]. This was supported by Pillai et al. stating that the applied electric field boosts the rearrangement of water molecules and increases the condensation efficiency [Pillai, R., Berry, J.D., Davidson, M.R., Electrolytic drops in an electric field: A numerical study of drop deformation and break up. Phys. Rev. (92), 013007 (2011); Aragones, J.L., MacDowell, L.G., Greiner, A. Phase Diagram of water under an applied electric field. Phys. Rev. (107), 155701 155704, (2011)].

[0009] Another explanation provided by La Mer and Healy on the effect of electric field on soil moisture is that the electric field influences the formation of invisible compressible monolayers of alcohols which are more resistant to evaporation in the surface and slows down the phase change of water from liquid to gas [Evaporation of water: its retardation by monolayers, Science (148), 36-42 (1965)]. These increase in resistance to evaporation is brought about by the simple straight-chain alcohols and acids, with alkyl chains free of branching and of double bonds forming the best condensed monolayers that are more resistant to evaporation.

[0010] The object of the invention is to provide a practical and effective implementation of SEF to usage to improve plant growth, biomass yield and soil moisture retention.

SUMMARY OF THE INVENTION

[0011] The invention provides a method of enhancing plant growth, biomass yield and retention of soil moisture content comprising of exposing the plants and the soil to a spatial electric field.

[0012] The invention also provides a system for enhancing plant growth, biomass

A yield and retention of moisture in soil, the system comprising a high voltage DC generator producing an electric potential, through an electrode suspended above the soil, and a ground connection to the soil, wherein the electric potential is applied between the electrode and the ground connection to generate a spatial electric field between the electrode and the soil.

[0013] Preferably the electric potential is in the range of +25kV to +45kV and the electrode is suspended between 1.5m and 2.5m above the soil, preferably the electrode is suspended approximately 2.Om above the soil.

[0014] In preference the electrode comprises a fine 0.6 mm stainless-steel wire.

[0015] It should be noted that any one of the aspects mentioned above may include any of the features of any of the other aspects mentioned above and may include any of the features of any of the embodiments described below as appropriate. By so doing, the method results in promoting growth and yield of plants and crops and soil moisture retention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows.

[0017] Figure 1 shows the installation of the SEF unit assembly in a specific control area.

[0018] Figure 2 displays the soil moisture retention mechanism by SEF through water vapor condensation and evaporation

[0019] Figure 3 illustrates the experiments on plant growth and biomass enhancement of barley using SEF at different fine HV wire elevation from the soil.

[0020] Figure 4 shows the trend in plant growth enhancement of barley in terms of plant height at variable HV wire elevation.

[0021] Figure 5 shows the trend in plant growth enhancement of barley in terms of biomass yield at variable HV wire elevation.

[0022] Figure 6 shows the vertical growth rate graph of pechays and lettuces indicated by a graph of the average plant height in cm with respect to time in days. Dotted trend lines correspond to observations from the greenhouse without SEF while solid lines are from the greenhouse with SEF.

[0023] Figure 7 illustrates the lateral growth rate graph which is a plot of the average leaf diameter in cm and with respect to time (days). Dotted trend lines correspond to observations from the greenhouse without SEF while solid lines are from the greenhouse with SEF.

[0024] Figure 8 presents the vertical plant growth rate of the heirloom and cherry tomatoes indicated by the plot between the average plant height in cm with time in days up to the 3 5 thdayaftertransplantation.

[0025] Figure 9 illustrates the controlled soil moisture retention without rehydration test set up.

[0026] Figure 10 presents the soil moisture reduction in the soil sample boxes (without soil rehydration) at 0 - 5cm and 5cm - 10cm soil depth.

[0027] Figure 11 shows the set up for the soil moisture content tests on barley with regular watering as soil rehydration at variable distance from of 1.5m - 2.5m from the HV electrode wire.

[0028] Figure 12 displays the soil moisture content without rehydration at 0-5cm soil layer at variable distance of 1.5m - 2.5m from the HV electrode wire.

[0029] Figure 13 presents the soil moisture content without rehydration at 5-10cm soil layer at variable distance of 1.5m - 2.5m from the HV electrode wire.

DRAWING COMPONENTS

The drawings include the following integers. 21 Control Box 22 power and signal cable connector cable 23 main HV DC generator 24 earth ground

HV insulators 26 fine HV electrode wire 27 rigid wall 28 positive electric field 29 small plants tall plants 31 soil/ground 32 condensing water vapor molecule 33 evaporating water vapor 34 electrode wire reaction mechanism for monolayer formation adjustable racks/poles 36 stainless steel tube 37 soil box frame elevation

DETAILED DESCRIPTION OF THE INVENTION

[0030] The following detailed description of the invention refers to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings and the following description to refer to the same and like parts. Dimensions of certain parts shown in the drawings may have been modified and/or exaggerated for the purposes of clarity or illustration.

[0031] The invention relates to the use of the high voltage DC generator to generate the spatial electric field (SEF) to promote plant growth which also relates to enhancement of the biomass yield through higher nitrogen uptake by plants. The SEF also enhances the uptake and absorption of other ions like calcium and bicarbonate, and carbon dioxide that results to improved photosynthetic activity prompting plants to thrive better in an electric field environment.

[0032] The SEF also promotes soil moisture retention as it ionizes the water vapor droplets in air forcing them to the ground, while the reaction taking place near the electrode wire forms invisible monolayers in the air that slows the rate of moisture evaporation from the soil back to the atmosphere.

[0033] The main HV DC generator used to apply the SEF delivers +25 to +45 kV (DC) and at least 0.5 mA of current. A specified control area can be a greenhouse or an open field with a maximum of 400 m 2 to be planted with any flowering or vegetative plants and crops per SEF unit. Alternatively, additional high voltage generators can be installed based on the ideal range per unit. Preferably, the SEF is distributed within the control area by using either wood or plastic insulators, installed between 1.5 to 2.5 m above the soil surface. The direct current of +25 kV to +40kV is supplied over the specified control area. In preference, the main HV DC generator and insulators are connected to each other by a 0.6 mm fine high voltage electrode wire made of copper, tungsten, stainless steel or any electrically conductive wire. The main HV DC generator is grounded to the earth to generate the positive spatial electric field between the HV electrode wires and the soil surface.

[0034] In a preferred embodiment, the high voltage (HV) DC generator (23) delivers a varying potential of +25 kV to +45 kV into the specific control area, as illustrated in Figure 1. The HV DC generator (23) is connected to a control box (21) by a cable connector (22). The ground wire (24) of the HV DC generator is terminated to the soil to distribute the positive spatial electric field (28) into the specific control area.

[0035] The control box (21) is installed onto the rigid wall (27) and within eye level to facilitate ease of turning the HV DC generator (23) on and off and for safety monitoring. The control box (21) can be installed as far as possible from the main HV DC generator (24) to prevent the interference of the SEF with the electronic control system.

[0036] The HV insulators (25), preferably plastics are least 1m but not more than 5m from the main HV DC generator (23) and from another HV insulator (25).

[0037] The high voltage fine electrode wire (26), which is preferably a 0.6mm stainless steel wire is attached from the main HV DC generator (23) and to each of the insulators (25), through their terminals.

[0038] The fine HV electrode wires (26) must be at least 1.5 m to 2.5 from the soil (31), with greater caution on not allowing the plants (29,30) or any of its part touching the fine HV electrode wire (26).

[0039] The main HV DC generator (23) delivers a positive electric field (28) upon the plants (29,30) and the soil/ground (31) which makes the ground act as a "capacitor". There is very little current delivered and flowing into the plants (29,30) and the soil (31), making it safe to touch the plants and the soil (31) while the SEF HV main DC generator (23) is turned on.

[0040] The small amount of current induced onto the soil (31) is the one that activates efficient ion transport leading to growth enhancement. This is explained earlier in a related publication by Black et al., who proved that supplying impulses ranging from a few to several microamps increases plant growth [Black, J.D., Forsyth, F.R., Fenson, D.S., Ross, R.B. (1971). Electrical Stimulation and its effects on growth and ion accumulation in tomato plants. Canadian Journal of Botany, 49(10), pp. 1809-1815]. It was also found that electrostimulation through small amounts of current into the soil and plant roots intensifies the uptake of elements and nutrients such as calcium, phosphorus and bicarbonates indicating that electrical impulses change in internal distribution of growth regulating compounds [Zhenyi, M., Liu, B. Greenhouse Space Electric Feld/C02 Co supplementation: Theory and Practice, Greenhouse Horticulture; China Academic Journal Electronic Publishing, pp. 31-32].

[0041] The SEF delivered by the fine HV electrode wire (26) stimulates the plants and its roots (9,10) by providing them with delicate electrical impulses (not too strong but not too weak), that can induce the cultivation of ion channels and ion transport, particularly the transport of calcium and bicarbonates in the plants. The plants (9,10) have the ability for underground communication through electrical transmission and there is an ultrafast electrical signal transmission between neighbouring plants through the soil. As explained, the electrical signals can travel and propagate inside the plants through the plasma membrane in the short distances on the plasmodesmata, and in long distances through the phloem [Volkov, A., Shtessel, Y.B. (2020). Underground electronic signal transmission between plants, Communication & Integrative Biology, 13(1), 54-58]. In combination, the varying or intermittent potentials generates several electronic signals that allows plants (9,10) to communicate and improve their quality. These electronic signalling aside from activating ion transport system of the plants also induce gene expression, enzymatic systems activation, enhance wound healing, plant cell repair and influence growth.

[0042] Also, the SEF generated within the air influence the moisture content of the soil (31) by several mechanism. First is that the EHD flow of the water vapor in air is being influenced by the positive electric field dragging the water vapor droplets into the soil [Reskinov, M., Salazar, M. Furtherprogress in electrostatic nucleation of water vapor. Proc. 2016 Electrostatics Joint Conference, 1-9 (2016)]. This phenomenon pushes the water vapor condensation into the soil.

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[0043] Second, the applied electric field onto the condensed water vapor molecule then alters the individual molecular architecture of condensing water droplets (32) into clusters of spherical shape molecules due to an increase in interfacial tension which increases the condensation efficiency of the system [Pillai, R., Berry, J.D., Davidson, M.R., Electrolytic drops in an electric field: A numerical study of drop deformation and break up. Phys. Rev. (92), 013007 (2011); Aragones, J.L., MacDowell, L.G., Greiner, A. Phase Diagram of water under an applied electric field. Phys. Rev. (107), 155701 155704, (2011)]. This in turn, improves the surface wettability of the soil on the condensation process of the water vapor [Wang, Q., Xie, H., Hu, Z., Liu, C. The impact of the electric field on the surface condensation of water vapor: Insight from molecular dynamics solution. Nanomaterials 9(64), 1-13 (2018)].

[0044] Third, is by a reaction mechanism (34) taking place near the fine HV electrode wire (26). While the SEF unit is turned on, the corona discharge from the fine HV electrode wire (26) ionizes the air, and reacts with the remaining water vapor in the air (see Figure 2). This reaction is governed by the transfer of 4 electrons forming an invisible compressible monolayer of (OH- molecules) alcohols which are more resistant to evaporation in the surface and slows down the change of water vapor droplets (31) back to the atmosphere. This phenomenon is theoretically explained by La Mer and Healy

[Evaporation of water: its retardation by monolayers, Science (148), 36-42 (1965)] stating that this increase in resistance to evaporation is brought about by the simple straight chain alcohols and acids, with alkyl chains free of branching and of double bonds forming the best condensed monolayers that are more resistant to evaporation.

EXAMPLE1

[0045] As per Figure 3 the plant growth enhancement of the SEF was tested at different heights above barley using fine HV electrode wire (26) elevated from the soil (31) and plant surface (30) of 1.5m to 2.5m using an adjustable rack (3(35) that holds the main HV DC generator (23) and the insulators (25). The fine HV electrode wire (26) and the plastic HV insulator (25) was connected to the main HV DC generator (23) with a stainless-steel tube (3(36) buried at the bottom of the soil sample box as earth ground .

When the SEF system is turned ON, a positive electric field (28) is generated between the fine HV electrode wire (26), the plants (30) and the soil (31).

[0046] The SEF unit was turned on for 20 days to monitor barley growth rate enhancement and biomass yield. The barley was grown in the standard and prescribed

in manner in the nursery before transplantation. The samples were transplanted into 4 soil sample boxes with 3 sample boxes being assigned as the test group at 1.5m, 2.Om and 2.5m distance from the fine HV electrode wire (26) and one sample box being assigned as the control group being placed 4 meters away from the test samples and shielded with a metal mesh. The plants are irrigated with 50 ml of water every day after sampling and measurements were completed. The plant heights were measured in mm, while the biomass yield was measured in grams.

[0047] The growth rate of barley in terms of plant height under the SEF is found to be higher than those in the control group. For the barley grown under SEF with a 1.5m HV electrode (26) wire elevation, a 13% increase in height was observed, while a 30% and 22% increase in height was recorded for the barley under SEF at 2.Om and 2.5m HV electrode wire (26) elevation, as shown in Figure 4. Similar findings were recorded with respect to the biomass yield of barley under SEF with a 14%, 28% and 16% increase over the control with respect to heights of 1.5m, 2.Om and 2.5m HV of the electrode wire (26) distance as illustrated in Figure 5. These increases in the plant height and biomass yield were attributed to the action of the SEF. The small currents introduced into the soil (31) by the SEF applied to the system effectively promoted plant growth and biomass yield was attributed to the efficient absorption of the plants roots of ions and nutrients present in the adequately aqueous soil.

[0048] From the table below, the soil moisture content of the samples retained under SEF was increased by 8% at fine HV electrode wire (26) elevation of 1.5m, 21% at 2.Om elevation and 13% at 2.5m fine HV electrode wire (26) elevation as compared to the control sample. This means that the soil moisture of the samples under SEF is preserved to support the dynamic absorption of nutrients in the soil.

Soil Moisture Content, %at different HV Time, wire elevation (m) days Control 1.5m 2.Om 2.5m 1 16.30 16.40 16.50 16.10 4 15.50 15.60 16.20 15.40 7 15.00 16.00 17.30 15.80 10 13.50 15.80 17.00 15.50 13 12.50 15.20 16.40 14.80 16 11.50 14.40 16.00 13.40 19 11.90 14.90 17.20 13.00 Average 13.74 15.47 16.66 14.86

1-1

%increase -- 13 21 8

[0049]

[0050] The enhancement is brought about by efficient water molecule splitting in the adequately wet soil. The separation of hydrogen and hydroxide in the soil primarily increases the oxygen content of the plant root system increasing root vitality. In addition, the large number of hydrogen ions in the root-soil interface forms a space leakage current which enhances cation exchange in the soil. At higher applied voltages, bicarbonate ions are transmitted by the root system enhancing further the ion exchange of various components enabling plants to thrive in the aerial high voltage electric field. Together with this reaction in the soil-root system is the efficient conversion of nitrogen in air to produce nitrogen dioxide or nitrites that are soluble in water, which is then introduced into the soil by the supply of the voltage and is readily absorbed by the soil into the root system primarily contributing to a faster and more efficient nitrogen uptake of the plants.

EXAMPLE2

[0051] Black Behi Pechays and Loose-Leaf Lettuces were grown in a nursery and transplanted into identical greenhouses. One of the greenhouses was installed with the SEF set up denoted as greenhouse with SEF illustrated while the other served as the control greenhouse or greenhouse without SEF.

[0052] The main HV DC generator (23) delivering +25 kV to +45kV was installed 3m from the ground, making the matured plant (29) about 2.0 m from the main HV DC generator (23), the HV insulators (25) and the electrode wire (26).

[0053] The variable potential applied to the system was theoretically explained as the main driving force that influences the plant growth rate. This is what Liu et al. termed as intermittent electric field exposure, which can encourage plant growth enhancement due to the varied amount potentials applied to the system over a period of time[Zhongjng, Y., Weihua, Z., Liu, B. (2015). Demisting and humidity reducing effect about greenhouse electric defogging health promotion and disease prevention system, J. Agricultural Engineering, 5(6), pp. 1-5.].

[0054] The plant height (cm), leaf diameter (cm) was recorded since day 1 of transplantation and every 5 days thereafter until the harvest date. This measurement is for the identification of the vertical and lateral growth rate of the crops. On the harvest date, total biomass yield and edible yield is measured in grams. Total biomass yield is the total mass of the plant upon harvest, while edible yield is the mass of the crop after removing dried, silted and deteriorated plant parts after its harvest.

[0055] Significant increases in the plant growth rate were observed in pechays in the greenhouse with SEF. The pechays in greenhouse with SEF was found to grow significantly faster than the pechays in greenhouse without SEF. The pechays in the greenhouse with SEF grow taller at the rate of 0.74 cm/day and wider at the rate of 0.48 cm/day as compared to the 0.57 cm/day vertical growth rate and 0.37/day lateral growth rate by the pechays in greenhouse without SEF. The pechays in greenhouse with SEF were found to grow taller by 41% compared to pechays grown in the greenhouse without SEF. The leaves of the pechays in the greenhouse with SEF were 30% larger than those grown in the greenhouse without SEF as illustrated in Figure 6.

[0056] Similar trends were observed with the lettuces. The lettuces in the greenhouse with SEF recorded a vertical growth rate of 0.56 cm/day and a lateral growth rate of 0.39 cm/day which is higher than that of the lettuces in the greenhouse without SEF of 0.51 cm/day and 0.27 cm/day, respectively. A 40% increase in the plant height of the lettuces and a 43% increase in leaf diameter of pechays in the greenhouse with SEF when compared to the lettuces grown in the greenhouse without SEF as illustrated in Figure 7.

[0057] The biomass yield of the pechays and lettuces in the greenhouse with SEF were found to be 40% and 36% respectively greater than the yields of the crops from the greenhouse without SEF. An increase of 51% and 46% was recorded for the pechays and lettuces in the greenhouse with SEF over the crops from the greenhouse without SEF.

Vertical Growth Rate Pechay Lettuce with SEF w/o SEF with SEF w/o SEF Plant Box (cm/day) (cm/day) (cm/day) (cm/day) P1 0.727 0.502 0.679 0.434 P2 0.749 0.518 0.684 0.504 P3 0.787 0.623 0.701 0.631 P4 0.763 0.503 0.692 0.398 Average 0.76 0.54 0.69 0.49 %Increase 41 40

[0058]

Lateral Growth rate

Pechay Lettuce with SEF w/o SEF with SEF w/o SEF Plant Box (cm/day) (cm/day) (cm/day) (cm/day) P1 0.356 0.321 0.270 0.247 P2 0.676 0.469 0.351 0.260 P3 0.492 0.421 0.478 0.313 P4 0.393 0.259 0.454 0.268 Average 0.48 0.37 0.39 0.27 % Increase 30 43

[0059]

[0060] Qualitative observations made throughout the pechay and lettuce experiments were also recorded. The leaves and trunks of pechays and lettuces in the greenhouse with SEF looked greener and healthier than those form greenhouse without SEF. The trunks of pechays in the greenhouse with SEF were more massive and whiter while a number of pechays in the greenhouse without SEF had purplish trunks, an indication of inefficient transport of water. The overall plant appearance of lettuces in the greenhouse with SEF were also more massive and more upright while several lettuces were found to have grown larger upon harvest. Several mortalities and stunted growth were observed among pechays and lettuces in the control greenhouse, while all crops from greenhouse with SEF had 100% growth success rate. The crops from the greenhouse without SEF were found to be infested with bugs and molds, with the latter appearing as block spots on the trunk near the roots, while there was absolutely no bugs or insects observed in the greenhouse with SEF. This means that SEF, also has the capability to protect plant from bugs and insects that may cause plant disease.

[0061] The plant-disease prevention capability of the SEF is most likely achieved through the deterrence of insects and pests due to the corona discharge from the fine HV electrode wire as explained by Matsuda et al. [Matsuda, Y., Toyoda H. (2018). Novel electrostatic devices for managing biotic and abiotic nuisances in environment, Open Access J. Sci. 2(5), pp. 337-353.] with the insect, in effect serving as a moving external electricity that enters areas covered by the SEF. This field exerts an electrostatic force to push external electricity out of the field to ground, soil and the plant body. It is more likely that insects are deprived of free electrons from their outer surface cuticle layer when they enter the electric field. As a result of electron deprivation, the insects will be positively electrified when they enter. Matsuda et al. also stated that insects have a way of detecting any harmful corona discharge through their antennae or exoskeleton extensions, which discourages them to attack plants under the SEF or if they do enter the field, they are

1A instantly killed. This explains why the plants in the greenhouse with SEF have remained free of any infestation over the duration of the experiment.

EXAMPLE 3

[0062] Heirloom and Cherry tomatoes were used and divided randomly into two groups during transplantation. One group was exposed to SEF and the other was not. The tomatoes were transplanted from seedlings to plant boxes.

[0063] In the greenhouse with SEF, the SEF unit was installed approximately 2.0 meters from the plants with its ground wire (24) terminated to the soil (31). These variety of tomatoes were expected to grow to almost a meter high. The tomato leaves and trunks (30) were pruned and trimmed to maintain the distance from the fine HV electrode wire (26).

[0064] The average vertical growth rate of the heirloom and cherry tomatoes in the greenhouse with SEF is found to be 2.58 cm/day, which is higher from the greenhouse without SEF at 2.10 cm/day. A similar trend was observed in the cherry tomatoes with a growth rate of 2.85 cm/day in the greenhouse with SEF and 2.52 cm/day from the greenhouse without SEF.

[0065] A 54% increase in biomass yield and 71% increase in the fruit yield of heirloom tomatoes was achieved in the greenhouse with SEF and a 50% increase in biomass yield and 53% increase in the fruit yield was achieved on cherry tomatoes. The average trunk diameters of the heirloom and cherry tomatoes in the greenhouse with SEF are 40% and 44% respectively larger than those in the greenhouse without SEF as shown in Figure 8.

Biomass Yield Heirloom Tomatoes Cherry Tomatoes with SEF w/o SEF with SEF w/o SEF Plant Box (grams) (grams) (grams) (grams) P1 3628 284 1972 1654 P2 5870 5570 4716 3258 P3 1286 1170 2552 1228 Average 10784 7024 9240 6140 %Increase 54 50

[0066]

Fruit Yield Plant Box Heirloom Tomatoes Cherry Tomatoes with SEF w/o SEF with SEF w/o SEF (gram) (cm/day) (cm/day) (cm/day) P1 1058 292 1258 510 P2 1796 1410 1664 1388 P3 946 524 1184 788 Average 3800 2226 4106 2686 % Increase 71 53

[0067]

[0068] There is no mortality or plant death observed among the tomatoes in the greenhouse with SEF while a mortality rate of 4.2% for heirloom tomatoes and 8.3% for cherry tomatoes in the greenhouse without SEF. This brings the seedling success rate of 100% on samples under SEF and 88% on the samples without SEF.

Plant Yield Heirloom Tomatoes Cherry Tomatoes Parameter withuot SEF with SEF without SEF with SEF Fruit Mass (grams) 2196 3400 2668 3468 % Increase using SEF 55 30

[0069] Mortality Rate, % 4.2 0.0 8.3 0.0

[0070] Other observations on the two groups of tomatoes were also noted and recorded. The tomato plants in the greenhouse with SEF appeared to be more massive, greener and taller with bigger trunks, in addition, they have been of a more consistent height. The tomatoes in the greenhouse with SEF seem to grow evenly over time. In terms of plant mortality, about 13% mortality rate was recorded in the greenhouse without SEF whereas there was zero plant mortality in the greenhouse with SEF. The tomato leaves and trunks were inspected after harvest and a number of tomato plants from the greenhouse without SEF were infested with caterpillars, small white flies, and some displayed signs of blighting and fungal attack. In comparison, tomato plants from the greenhouse with SEF were all are free of insects and mould. On the harvest date, the tomato plants in the greenhouse with SEF were found to have fully ripe fruits by day 65, whereas a number of tomato plants in the greenhouse without SEF did not bear any fruit.

EXAMPLE4

[0071] The soil moisture retention was conducted using airdried and sieved (2mm) test soils loaded into the soil sample boxes (3(34) 58cm x 40cm x 30cm, filled with water allowing water to seep fully into the soil. To prevent further evaporation, the soil boxes were covered with a plastic film and allowed to stabilize for two days before assigning into experimental (SEF) and control group. Half of the soil boxes were assigned as SEF group and the other half as the control group. The SEF and the control group were held separately in two adjacent rooms with controlled relative humidity of % to 30% and temperatures of 150 C to 180 C.

[0072] In the SEF test chamber shown in Figure 9, two height adjustment racks (3(35) with plastic HV insulators (25) are cantered in the direction of the length of the soil samples. The plastic HV insulators (25) are 3 m apart and the fine HV electrode wire (26) is fixed to the tip of the plastic HV insulator (25) with a nut. The fine HV electrode wire (26) and the plastic HV insulator (25) was connected to the main HV DC generator (23) with a stainless-steel tube (3(36) buried at the bottom of the soil sample box as earth ground (25). When the SEF system is turned ON, a positive electric field (28) is generated between the fine HV electrode wire (26) and the soil (31).

[0073] The experimental group was exposed to the SEF for 31 days. The SEF fine HV electrode wire (27) was held 2.5 meters above the soil 31) surface (of the soil sample box).

[0074] Using a soil drill, every 3 days, stratified / layered soil samples were collected every 5 cm from the bottom of the soil box in three lots, and averaged to determine the actual soil moisture content at 0-5cm and 5cm-10 cm. The wet soil samples were transferred to aluminium dishes and dried in a vacuum oven to measure the soil moisture content.

[0075] The average soil moisture content was determined by difference using the dry weighing method formula:

[0076] Soil Moisture % = W X100 where wi is the weight of the empty

aluminium dish,w2 is the weight of the aluminium dish with wet soil sample, andw 3 weight of the aluminium dish with the dried soil sample. No sample rehydration was administered during the conduction of the experiment.

[0077] Significant differences in the soil moisture content were noted between the SEF and the control group for both soil depths of 0-5 cm with p-values of <0.0001 and at 5-10 cm with p-values also of less than <0.001. In the beginning, the soil moisture evaporation rate of the SEF and control group are almost the same. By day 7 onwards, a significant reduction in soil moisture content is observed in the control group, while the soil moisture content of the samples under the SEF remains stable. From Figure 10, after 30 days, the moisture content at 0-10 cm soil samples from the control group decreased from 31% to 16%, with a dry soil layer being formed on the soil surface and large desiccation cracks started to appear during the latter sampling period. This gives an average daily soil moisture evaporation rate of 0.5%. This means that over the 30 day test period, the control set-up lost 48% of the moisture in the soil and retained only 52% of the initial moisture. Under SEF conditions, the average soil moisture content at -10 cm soil samples was found to evaporate slowly changing from 32% to 28% over the 30-day test period, giving an average daily 0.13% soil moisture reduction. This means that the samples under SEF retained 93% of the moisture and lost only 6% over the 30-day period. This is further evidenced by the soil surface appearance which is still very moist indicating the SEF can inhibit or retard moisture evaporation.

EXAMPLE 5

[0078] The soil moisture changes and evapotranspiration were tested on soil sample boxes transplanted with barley seeds grown in a nursery. The plants are allowed to acclimatize with the environment for three days before subjecting the samples under SEF and the control group.

[0079] The experimental group was placed under the SEF at a 1.5m, 2.Om and 2.5m distance from the soil surface (31). Two adjustable insulator racks (35) are placed at each end of the room to adjust the height of the fine HV electrode wire (26) from the plants to the experimental heights as soon as the plants starts growing as shown in Figure 11.

[0080] Another sample box (34) is placed 4m away from and outside the SEF section and is shielded with a metal mesh as the control group. The soils used are airdried, sieved (2mm) and stabilized before barley transplantation. Data collection was done every 3 days and the barleys were rehydrated equally with 50 ml of water after sampling.

[0081] The SEF unit was turned on for 20 days after transplantation to monitor the overall evapotranspiration of the system.

[0082] During data collection, soil sampling is performed using a soil drill. Stratified or layered soil samples were collected every 5 cm, 10 cm from the bottom of the soil box in three lots, every 3 days using a soil drill and averaged to determine the actual

1A: soil moisture content at 10-15 cm and 15-20 cm. The wet soil sample were transferred to an aluminium dish and dried to account for the soil moisture content. The soil moisture content was determined by difference from the weight of the empty pan/dish, weight of the pan/dish with wet soil sample and the weight of the pan/dish with dried soil sample.

[0083] The evapotranspiration, which is a measure of the movement of water within the plant and the subsequent exit of water vapor from the plant's stomata, is measured using the relationship between soil moisture and other electric field conditions with formulas Whi= 101Hi *psoil*Mhwhere Whisoil moisture (mm), Hiis the thickness of the first soil layer (cm), soil is the density of soil in g/cm 2 and Mh, is the moisture content of the first layer of soil. The evapotranspiration (mm) on the other hand is determined using the formula T + Es = / - AWwhere T is the crop transpiration (mm), Es is the soil evaporation (mm), I is the water volume and AWchange in soil moisture content

[Shuying, C., Xuying, L., Liu, T-P., Liu, B-J. Impact of electric field on soil moisture and growth of barley. Journal of Agricultural Engineering Transactions of CSAE, 26(2), 59 63(2010)].

[0084] The soil moisture in of the SEF samples were all found to be higher than the control samples as illustrated in Figure 12. At soil a sampling depth of 10-15 cm, the samples with 1.5 m, 2.0m and 2.5m SEF elevation were found to have 34%, 55% and 26% more soil moisture, respectively as compared with the control samples. A similar trend was noted at a soil sampling depth of 15-20 cm with 25%, 25% and 9% increases in soil moisture for SEF samples that are 1.5m, 2.0m, and 2.5m SEF elevation, as seen in Figure 13. Both Figures 12 and 13 as well as the table below indicate that optimum soil moisture retention in soil samples with plants can be achieved at an SEF elevation of 2.0m.

Increase in Soil Moisture, %

Soil Depth SEF elevation (m)

(cm) 1.5 2.0 2.5

10-15 34 55 26

15-20 25 45 9

[0085]

1a

[0086] The lesser values of evapotranspiration in mm in the samples under SEF at different SEF elevation indicates slower evapotranspiration as compared to the evapotranspiration in the control group. With the total evapotranspiration in the control group observed to be the highest at 35.5, which is about 1.4. to 2.2 times that of the samples under SEF. This means that the SEF can reduce the evapotranspiration inside the system. The evapotranspiration at an SEF distance of 2.Om and 2.5m is 63% and 72% of the evapotranspiration occurring at 1.5m SEF elevation. With this, the reduction in evapotranspiration is optimum at SEF elevation of 2.Om which is 44% of the evapotranspiration rate taking place without the SEF.

SEF elevation (m)

Parameter Control 1.5 2.0 2.5

Evapotranspiration, T (mm) 35.5 25.2 15.8 21.8 Ratio with Control - 1.4 1.6 2.2

%,Relative with Control - 71 44 61

%,Relative T with 1.5m - 100 63 72

[0087]

EXAMPLE 6

[0088] Actual air moisture measurements were conducted using floating seedling test and control greenhouses. The test greenhouses were installed with the two SEF units the fine HV electrode wire (26) installed at a height of 2.Om from the soil (31) transplanted with tobacco seedlings that are matured enough and suitable for transplantation based on the guidelines in GB/T 25241.1-2010 [Rules for Tobacco Intensive Seedling Production-Part 1: Seeding with floating system, National Standard, PROC (2010)]. No SEF units were installed in the control greenhouse without SEF.

[0089] The positive spatial electric field (28) was generated into the system by earth grounding the main HV DC generator (23) with its ground wire (25) directly submerged into the soil/ground (31) of the floating seedling facility. The ventilation fins of the test greenhouses were maintained closed while they were always open in the control greenhouse due to humidity.

[0090] The air moisture content is measured using the air moisture absorption method with P 20 5water vapor harvesting agent. The greenhouses were equipped with

U-shaped tubes loaded with 10 g of P 2 05 with air volumetric flowrate controlled at 300 mL/min. The air moisture content (mg/L) was calculated from the displacement and mass changes data of the P 205 inside the U-shape tube (g) and the sample volume (V)

indicated by the flow meter (L) using the formula X =(-2--) V x 1000, where X is the air

moisture mi and m2 is the initial mass of the U-shape tube with P 205 . Relative humidity, temperature and plant growth were also measured.

[0091] To account for the fluctuation in the relative humidity and temperature that directly affects the volume of water vapor molecules in air as well, the air moisture content was measured 3 times a day; 9:00 AM, 11:00 AM and 17:00 PM. The obtained values were averaged to describe daily trend.

[0092] The average daily air moisture content in the greenhouse with SEF was found to be 0.41 mg/L and 0.74 mg/L for the greenhouse without SEF. The lesser air moisture content in the greenhouse with SEF indicates lesser water vapor content of the air inside the test areas. The lesser air moisture content in the greenhouse with SEF indicates that there is prolonged condensation of water vapor into the soil which is then attributed to reduced soil moisture evaporation.

Air Moisture Content, (mg/L)

Sampling Day5 Day 10

Time with SEF Control with SEF Control

9:00 AM 0.39 0.71 0.4 0.79 11:00 AM 0.30 0.48 0.49 0.73 17:00 PM 0.39 0.83 0.47 0.57

Average 0.36 0.67 0.45 0.8

Daily 0.41 0.74

Reduction, % 46 -- 44 -

[0093]

Relative Humidity, %

Sampling Day 5 Day 10 Time with SEF Control with SEF Control 9:00 AM 80 82 80 83 T, °C 8 7 10 9 11:00 AM 74 77 72 73

T, °C 13 12 17 15 17:00 PM 83 87 83 86 T, °C 11 11 12 11 Average 79 82 78 81 Reduction, % 3 -- 3 -

[0094]

[0095] The lowest average daily air moisture content of the greenhouse with SEF is accompanied by lower average relative humidity and temperature. The temperature in the greenhouse with SEF was found to be 0.5 - 2.0°C higher than that of the control green house. This rise in temperature is accompanied by a slightly lower relative humidity. The results further reveal that a 3% reduction in relative humidity under the SEF environment is equivalent to about 40% reduction in air moisture content. In addition, improvements in seedling time yield were observed in the greenhouse with SEF. The tobacco plants in the greenhouse with SEF were found to grow and develop 5 days ahead of the growth and development of the tobacco plants in the control greenhouse. More seeds were also observed to sprout in the greenhouse with SEF with a higher seedling success rate of 91% over the 89% success rate of those of the control greenhouse. In addition, the slight increase in temperature in the greenhouse with SEF provides a more conducive environment for seedling growth and development by generating an insulation effect, while the lowered humidity in the greenhouse with SEF tends to reduce the occurrence of plant diseases.

Time, Days Success Rate

Treatment Seedling Transplanting %

Control 87 89 91

with SEF 82 84 93

[0096]

[0097] The transplanting time of seedlings in greenhouse with SEF was 5 days earlier than that of the seedlings in the control greenhouse. The spatial electric field through the high voltage electrode wire in the test greenhouse ionizes the air enabling the conversion or nitrogen in air to nitrates and oxidation of oxides, particularly into carbon dioxides which is readily forced into the ground plant absorption. Similarly, the small milliamps of current running introduced into the soil by spatial electric field improves ionic discharge into soil and enhancing calcium and bicarbonate root

91? absorption.

[0098] This indicates that the SEF produces a dehumidification and defogging effect in the test greenhouse that eventually reduced the ventilation requirement, enhanced the insulation of the area and prevent diseases by the slight elevation of temperature and reduced relative humidity, as well as efficient condensation and reduced evaporation of moisture into the air, which leads to better ionic discharge into the soil and efficient ion absorption of the plant roots.

[0099] The reader will now appreciate the invention which provides a practical and effective implementation of SEF to usage to improve plant growth, biomass yield and soil moisture retention.

[00100] Further advantages and improvements may very well be made to the present invention without deviating from its scope. Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus. Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in this field.

[00101] In the present specification and claims (if any), the word "comprising" and its derivatives including "comprises" and "comprise" include each of the stated integers but does not exclude the inclusion of one or more further integers.

Claims (6)

1. A method of enhancing plant growth, biomass yield and retention of soil moisture content comprising of exposing the plants and the soil to a spatial electric field.

2. A system for enhancing plant growth, biomass yield and retention of moisture in

soil, the system comprising a high voltage DC generator producing an electric potential,

through an electrode suspended above the soil, and a ground connection to the soil,

wherein the electric potential is applied between the electrode and the ground

connection to generate a spatial electric field between the electrode and the soil.

3. A system as in claim 2, wherein the electric potential is in the range of +25kV to

+45kV.

4. A system as in claim 2 and 3, wherein the electrode is suspended between 1.5m

and 2.5m above the soil.

5. A system as in any one of claims 2 or 3, wherein the electrode is suspended

approximately 2.Om above the soil.

6. A system as in any one of claims 2 to 5, wherein the electrode comprises a fine

0.6 mm stainless-steel wire.

9A

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