Method for growing plants

Abstract

The invention relates to a coherent propagation growth substrate product (1) formed of man-made vitreous fibres (MMVF), the product (1) having two opposed top and bottom surfaces and at least one cavity (2) which is open at the top surface and which extends from the top surface towards the bottom surface, wherein a superabsorbent polymer (3) is provided in the cavity (2).

Claims

1. A method of cultivating plants comprising: providing a coherent propagation growth substrate product formed of man-made vitreous fibres (MMVF), the product having a top surface which is opposed to a bottom surface and at least one cavity which is open at the top surface and which extends from the top surface towards the bottom surface, wherein the growth substrate product includes a region surrounding the cavity which has a higher density than the remainder of the growth substrate product; placing, in the at least one cavity, a superabsorbent polymer that is in dry, flowable form; positioning a seed in the cavity, irrigating the growth substrate product and allowing germination and growth of the seed to form a seedling; transplanting the seedling by positioning the growth substrate product on the ground; and irrigating the growth substrate product and allowing growth of the seedling and allowing the seedling to root into the ground.

2. A method according to claim 1, wherein the depth of the cavity is 20 to 80% of a height of the growth substrate.

3. A method according to claim 1, wherein a volume of the growth substrate is in the range 3 to 150 cm.sup.3.

4. A method according to claim 1, wherein a volume of the growth substrate is in the range 300 to 1500 cm.sup.3.

5. A method according to claim 1, wherein a volume of the cavity is 3% to 60% of the volume of the growth substrate.

6. A method according to claim 5, wherein a volume of the cavity is 10% to 50% of the volume of the growth substrate.

7. A method according to claim 1, wherein the MMVF has an average density of from 50 to 140 kg/m.sup.3.

8. A method according to claim 1, wherein the superabsorbent polymer is in dry granular form.

9. A method according to claim 1, wherein the at least one cavity extends the entire distance through the height of the growth substrate product and wherein the at least one cavity has a varying cross-sectional area such that the at least one cavity is sufficiently narrow at the bottom of the growth substrate product that the superabsorbent polymer is prevented from falling out of the at least one cavity.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows a vertical cross-section of a growth substrate product of the invention.

(2) FIG. 2 shows a vertical cross-section of a further growth substrate product of the invention.

(3) FIG. 3 shows a vertical cross-section of another growth substrate product of the invention.

(4) FIG. 4 shows a vertical cross-section of yet a further growth substrate product of the invention.

(5) FIG. 5 shows a plan view of yet a further growth substrate product of the invention.

(6) FIG. 6 shows a perspective view of yet a further growth substrate product of the invention.

(7) FIG. 7 shows the water holding capacity of an MMVF substrate compared to silt loam as discussed in Example 1 below.

DETAILED DESCRIPTION OF DRAWINGS

(8) FIG. 1 shows a vertical cross-section of a growth substrate product 1 of the invention. The cavity 2 has a rectangular vertical cross-section and extends 30% of the height through the product (the depth of the cavity is 30% of the height of the product). Such a cavity could be formed by drilling or punching a coherent MMVF substrate. The cavity 2 is filled with superabsorbent polymer 3. A seed or seedling may be placed in the cavity 2.

(9) FIG. 2 shows a vertical cross-section of a growth substrate product 1 of the invention. The cavity 2 is shown with a rectangular cross-section extending 80% of the height through the product. Such a cavity could be formed by drilling or punching a coherent MMVF substrate. The cavity 2 has a number of dry superabsorbent polymer granules 4 at the bottom. A seed or seedling may be placed in the cavity 2.

(10) FIG. 3 shows a vertical cross-section of a growth substrate product 1 of the invention. The cavity 2 has a narrower width at the top of the cavity than in the lower portion of the cavity. The cavity 2 extends 70% of the height through the product. Such a cavity could be formed by drilling a coherent MMVF substrate. The cavity 2 is partially filled with hydrated superabsorbent polymer 3. A seed or seedling may be placed in the cavity 2.

(11) FIG. 4 shows a vertical cross-section of a growth substrate product 1 of the invention. The cavity 2 is shown extending the whole way through the product. The cavity has a greater width at the top of the cavity than at the bottom of the cavity. The cavity 2 comprises a number of dry superabsorbent polymer granules 4 which are lodged part way down the cavity 2 and are of sufficient size not to fall out of the cavity 2. A seed or seedling may be placed in the cavity 2.

(12) FIG. 5 shows a plan view of yet a further growth substrate product of the invention. The cavity 2 is shown positioned substantially centrally in the cylindrical growth product 1.

(13) FIG. 6 shows a perspective view of yet a further growth substrate product of the invention. The growth substrate 1 is shown with a cavity 2.

(14) FIG. 7 shows water retention curves for a MMVF substrate and silt loam.

(15) The invention will now be described with reference to the following non-limiting examples.

Example 1

(16) The water holding capacity of a MMVF substrate and silt loam were tested in accordance with EN 13041-1999. The MMVF substrate was a stone wool fibre product with a phenol-urea formaldehyde (PUF) binder and a non-ionic surfactant wetting agent. The results are shown in FIG. 7.

(17) The MMVF substrate has a maximum water content of 90% vol. When the MMVF substrate gives off water, it retains about 2-5% vol of water. This means that the MMVF substrate has a buffering capacity of 85-87% vol. This shows that the MMVF substrate has a high maximum water content, as well as a lower water retention level.

(18) The maximum water content of the silt loam is lower than the MMVF substrate. The capillarity of the silt loam is much higher than that of the MMVF substrate, which means a suction pressure of several meters is needed to withdraw water from the silt loam. This means that the silt loam soil will easily drain water from the MMVF substrate as soon as the soil is no longer fully saturated. This demonstrates that water will drain from a MMVF substrate into the ground when the soil is not saturated.

Example 2

SAP (Superabsorbent Polymer) Examples

(19) Plugs made of a stone wool fibre product with a cured hydrophilic binder were provided. The plugs were cylindrical with a height of 28 mm and a diameter of 20 mm. Each plug was drilled to form a cylindrical cavity that had a height of 15 mm and a diameter of 5 mm. In the examples of the invention, five dry granules of superabsorbent polymer were positioned at the bottom of the cavity. The plugs were completely saturated with nutrient solution. A tomato seed was planted in each plug. After 14 days of growth, the plugs were planted in a garden soil mixture with a water content of either 30% or 50%. After a further 3, 7 and 14 days the weights of the plants were measured.

Reference Examples

(20) The reference examples were plugs made of a stone wool fibre product with a cured hydrophilic binder. The plugs were cylindrical with a height of 28 mm and a diameter of 20 mm. No cavity was created in the reference samples and no SAP was present. The plugs were completely saturated with nutrient solution. A tomato seed was planted in each plug. After 14 days of growth, the plugs were planted in a garden soil mixture with a water content of either 30% or 50%. After a further 3, 7 and 14 days the weights of the plants were measured.

(21) Results:

(22) TABLE-US-00001 TABLE 1 Overview planted tomato seeds in plugs Reference SAP Planted tomato seeds Number of plants Number of plants Planted 120 112 Usable 91 (76%) 90 (80%) Withered 18 (15%) 13 (12%) Not germinated 11 (9%)  9 (8%)

(23) Table 1 shows that there were a greater proportion of usable plants when the SAP plugs were used than when the reference plugs were used.

(24) TABLE-US-00002 TABLE 2 Average weight of the plants Average weight Reference SAP Plateau Plateau Plateau Plateau 1 2 Average 1 2 Average % Days g. g. g. g. g. g. 30 3 0.64 0.55 0.60 0.45 0.49 0.47 7 0.87 0.78 0.83 0.63 0.68 0.66 14 0.61 0.94 0.77 0.62 1.04 0.83 50 3 0.66 0.61 0.64 0.55 0.52 0.54 7 0.85 0.81 0.83 0.79 0.74 0.77 14 0.81 0.99 0.90 0.80 1.05 0.92

(25) Table 2 shows that when the water content of the soil was 30%, after both 3 and 7 days, the reference plants seem to perform better than the SAP plants. However after 14 days the SAP plants perform better than the reference plants.

(26) Table 2 shows that when the water content of the soil was 50%, after both 3 and 7 days, the reference plants seem to perform better than the SAP plants. However after 14 days the SAP plants perform about the same as the reference plants.

(27) Example 1 shows that the suction pressure of silt loam and MMVF is equal at about 50% water content. This means that the water does not drain from the MMVF plugs when the water content of the soil is 50%. This means that there is the same level of water available in the MMVF substrate in both the SAP plugs and the reference plugs. The SAP therefore has a negligible effect when the water content of the soil is 50%. When the water content of the soil is 30%, water will drain from the MMVF to the soil.

(28) The plants were larger when a larger amount of water is available as shown by comparing the values at 30% water content in the soil and 50% water content in the soil. This shows that when the soil contains 50% water, the growth substrate product contains sufficient water to maintain the plant and the SAP has negligible effect as water is maintained in the MMVF part of the plug. When the soil contains 30% water, water drains from the MMVF part of the plug, but is retained in the SAP. This means that the seed and seedling have access to the water in the SAP and thus the SAP has a positive effect on the growth of the plant. This shows the advantage of the plugs containing SAP when water drains from the MMVF part of the plug into the soil due to the higher suction pressure of soil.

(29) The results therefore show that the plugs of the invention achieve the aim of providing a water source to seedlings transplanted into the soil when the water content in the soil is less than the suction pressure of MMVF.

(30) It will be appreciated by the skilled person that any of the preferred features of the invention may be combined in order to produce a preferred method, product or use of the invention.