Polyurethane foam for use as soil improver

Abstract

Polyurethane foam flakes for use as additive to soil and/or other natural plant growth media for improving the water retention and/or reduction of the methane emission.

Claims

1. A plant growth substrate comprising: soil and/or other natural growth media, and polyurethane foam flakes as an additive; wherein the polyurethane foam flakes have a density of 25-100 kg/m.sup.3, a compression load deflection (CLD) at 40% of 5-50 kPa, a volume increase at water saturation of at most 25% and a water buffer capacity of 35-80%, wherein the polyurethane foam flakes have dimensions in the range 0.1-100 mm, and wherein the polyurethane foam flakes are present in the plant growth substrate in an amount ranging from 15 to 60 volume % where the volume % is calculated as the volume of polyurethane foam flakes in the total volume of plant growth substrate comprising the polyurethane foam flakes when the soil and/or other natural grown media are under aerobic conditions.

2. The plant growth substrate according to claim 1, wherein the polyurethane foam flakes have a CLD in the range 5-15 kPa, a free-rise core density of 25 up to 70 kg/m.sup.3, and a water buffer capacity of 40-60%.

3. The plant growth substrate according to claim 1, wherein the polyurethane foam flakes have a CLD of at least 20 kPa, a free-rise core density of 20 up to 50 kg/m.sup.3, a resilience of at most 30% and the volume increase at water saturation is at most 20%.

4. The plant growth substrate according to claim 1, wherein the polyurethane foam flakes have a resilience of at most 40%, a compression load deflection (CLD) at 40% of at least 16 kPa, a free-rise core density of at least 20 kg/m.sup.3, and a volume increase at water saturation of at most 25%.

5. The plant growth substrate according to claim 1, wherein the polyurethane foam flakes have dimensions in the range of 1-50 mm.

6. The plant growth substrate according to claim 1, wherein the polyurethane foam flakes are coated with fertilizers or hardeners.

7. The plant growth substrate according to claim 1, wherein the polyurethane foam flakes have dimensions in the range of 1-50 mm.

8. The plant growth substrate according to claim 1, wherein the polyurethane foam flakes are coated with fertilizers or hardeners.

9. A plant growth substrate comprising: soil and/or other natural growth media, and polyurethane foam flakes as an additive; wherein the polyurethane foam flakes have a density of 25-100 kg/m.sup.3, a compression load deflection (CLD) at 40% of 5-50 kPa, a volume increase at water saturation of at most 25% and a water buffer capacity of 35-80%, wherein the polyurethane foam flakes have dimensions in the range 0.1-100 mm, and wherein the amount of soil and/or other natural growth media to polyurethane foam flakes in the plant growth substrate has a volume ratio ranging from 10:90 to 90:10 volume % where the volume % is calculated as the volume of polyurethane foam flakes in the total volume of plant growth substrate comprising the polyurethane foam flakes when the soil and/or other natural grown media are under anaerobic conditions.

10. The plant growth substrate according to claim 9, wherein the polyurethane foam flakes have a CLD in the range 5-15 kPa, a free-rise core density of 25 up to 70 kg/m.sup.3, and a water buffer capacity of 40-60%.

11. The plant growth substrate according to claim 9, wherein the polyurethane foam flakes have a CLD of at least 20 kPa, a free-rise core density of 20 up to 50 kg/m.sup.3, a resilience of at most 30% and the volume increase at water saturation is at most 20%.

12. The plant growth substrate according to claim 9, wherein the polyurethane foam flakes have a resilience of at most 40%, a compression load deflection (CLD) at 40% of at least 16 kPa, a free-rise core density of at least 20 kg/m.sup.3, and a volume increase at water saturation of at most 25%.

Description

FIGURES

(1) FIG. 1 illustrates the reduction of methane gas emission when growing rice plants according to the invention whereby 75 vol % polyurethane flakes according to the invention are added to soil compared to the methane gas emission when growing rice plants on soil without addition of polyurethane flakes.

(2) FIG. 2 illustrates the set up of a plot according to experiment 2.

(3) FIG. 3 illustrates the effect of different water regimes on the yield of plants grown on plant substrates with additions of polyurethane flakes compared to the effect of different water regimes on the yield of plants grown on plant substrates without additions of polyurethane flakes.

(4) FIG. 4 illustrates the yield and growth results obtained for olive plants grown on plant substrates with varying additions of polyurethane flakes according to the invention.

EXAMPLES

(5) The invention is further illustrated with the following experiments and examples.

Experiment 1: Cultivation of Rice

(6) A polyurethane foam was made as follows.

(7) Polyisocyanate was reacted with a mixture of 7.9 pbw of Daltocel F442, 47.5 pbw of Daltocel? F489, 0.6 pbw of Jeffcat? DPA and 0.05 pbw of Jeffcat? ZF-10 (being obtainable from Huntsman; Daltocel? and Jeffcat? are trademarks of the Huntsman Corporation or an affiliate thereof which has been registered in one or more but not all countries) and 0.25 pbw of Tegostab? B 8724 LF (a surfactant ex Evonik) and 5.1 pbw of water at an isocyanate index of 39.5 and a water index of 280.

(8) The polyisocyanate used was a prepolymer obtained by reacting 54 pbw of Suprasec? 2185 and 36 pbw Suprasec? MPR (polyisocyanates ex Huntsman) and 10 pbw of Polyol 3380 (a polyoxyethylene triol ex Perstorp having an OH value of 382 mg KOH/g) and having an NCO value of about 25.9% w.

(9) The foam had a density of about 30 kg/m.sup.3, a CLD at 40% of 8.4 kPa, a volume increase at water saturation of about 17% and a WBC of about 67%.

(10) The foam so obtained was cut in flakes having an average particle size of at most 25 mm (mesh sieve).

(11) Rice was cultivated as follows (example 1 which is a comparative example not using foam): in a rectangle container of 100*100*15 cm, a soil layer of 12 cm humus was applied and on top of the humus a layer of about 1 cm clay. The soil was flooded with 2 cm of water and 500 rice seeds were sown. The sun-light was mimicked with a Bio Green plant light Sirus X400 (UV lamp) and Tansun RIO IP infrared heater of 2000 W. The UV lamp was used for 12 hours per day.

(12) In another cultivating example (example 2) the soil was replaced with a mixture of the same soil and the above flakes of polyurethane foam in a 25/75 volume ratio. This cultivating example was conducted concurrently with the previous one.

(13) During the cultivation period the amount of emitted methane was measured in a way similar to the method described in Acta Meteorologica Sinica (1990) Vol. 4, No. 3, pages 265-275. In example 1 the amount of emitted methane was about 9 times higher than the amount in example 2.

Experiment 2: Addition of Polyurethane Flakes to Soil and Effect on Yield of Tomato Plants Grown on that Soil

(14) The main purpose of the study is to determine the plant yield and reduction of water usage (irrigation) when using various concentrations of flakes in soil according to the invention (made using Type I polyurethane foam). To set up that experiment different plots were set up thereby using different amounts (vol %) of flakes in soil and different amounts of soil (depth profile) treated with flakes according to the invention.

(15) The main characteristics of the soil that was used in this field experiments was soil which has the following composition: 38% of silt (2-50 ?m); 42% of clay (0-2 ?m); 20% of sand (50-2000 ?m).

(16) For each plot (sample), the following five steps were undertaken: Remove a layer of 10 cm of soil and put it aside for use as UV protective layer, Enlighten the soil using a motoculteur up to the depth corresponding to the amount of soil to be mixed with the flakes; Take such enlightened soil into a mixer (b?tonni?re); Add the required volume/weight of flakes into the mixer, slightly watered to avoid it to be blown away by the wind; Mix both components; Spread out homogeneously the obtained mix over the relevant plot; Cover the plot with a 10 cm thick UV protective layer using the soil put aside (step 1).

(17) To simplify the layout, the different plots were organised into an array of 12 columns by 15 rows. The plots had dimensions of 16 m.sup.2 large and should be separated by a buffer of around 2 m in both directions (FIG. 2 illustrates the set up of a plot). Within each plot there are 3 areas: 1. The ?Buffer area? is the area that is not used for the experiment but used to separate the different plots from each other. This area will have no flakes inserted in the soil. 2. The ?Sampling area? is where samples of soil and crops will be taken, preferably close to the border with the ?Measuring area? in order not to disturb the real measuring area for yield and other parameters. This area will have additions of flakes in the soil and an irrigation regime as described by the model. 3. The ?Measuring area? is where the measure of yield and other parameters will be performed. This area will have the additions of flakes to the soil and an irrigation regime as described by the model.

(18) An irrigation system was installed thereby taking the irrigation requirement for each plot into account. Irrigation will be performed via drop-by-drop method using pipes pierced with small holes and one valve per irrigation zone (21 such zones are defined). The quantity of water is measured by a flow meter installed on the main pipe. All valves will be opened at the same time and switched off when the expected amount of water has been supplied to each individual irrigation zone. In order to facilitate the installation and control of the irrigation system, plots requiring the same level of irrigation have been aligned side by side.

(19) Tomato plants were planted into each plot. All tomato plants are 10-12 cm high and 2 weeks old when they were planted in the soil. During the first 2-3 weeks, irrigation was performed with 100% of optimal water supply on ALL plots in order to make sure that the plants develop a root system. After that, irrigation on the different plots was performed as prescribed in the irrigation requirement table below (Table 2). Table 3 summarizes the amount (vol %) of flakes according to the invention added to the soil in each plot.

(20) TABLE-US-00002 TABLE 2 irrigation requirement per plot in experiment 2. A B C D E F G H I J K L 1 20% 20% 20% 35% 35% 35% 35% 35% 35% 20% 20% 20% 2 35% 35% 35% 60% 60% 60% 60% 60% 60% 35% 35% 35% 3 60% 60% 60% 60% 60% 60% 60% 60% 60% 60% 60% 60% 4 85% 85% 85% 85% 85% 85% 85% 85% 85% 85% 85% 85% 5 100% 100% 100% 100% 100% Spare 100% 100% 100% 100% 100% spare 6 Spare 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% Spare 7 85% 85% 85% 85% 85% 85% 85% 85% 85% 85% 85% 85% 8 60% 60% 60% 60% 60% 60% 60% 60% 60% 60% 60% 60% 9 35% 35% 35% 60% 60% 60% 60% 60% 60% 35% 35% 35% 10 20% 20% 20% 35% 35% 35% 35% 35% 35% 20% 20% 20% 11 20% 20% 20% 35% 35% 35% 35% 35% 35% 20% 20% 20% 12 35% 35% 35% 60% 60% 60% 60% 60% 60% 35% 35% 35% 13 60% 60% 60% 60% 60% 60% 60% 60% 60% 60% 60% 60% 14 85% 85% 85% 85% 85% 85% 85% 85% 85% 85% 85% 85% 15 100% 100% 100% 100% 100% spare Spare 100% 100% 100% 100% 100%

(21) TABLE-US-00003 TABLE 3 volume % flakes added to the soil in each plot in experiment 2. A B C D E F G H I J K L 1 40% 55% 25% 25% 55% 40% 2 55% 25% 40% 40% 15% 40% 40% 25% 55% 3 40% 65% 40% 40% 40% 65% 40% 15% 40% 4 55% 25% 55% 25% 55% 55% 25% 25% 5 40% 40% 75% Spare 65% 40% 65% spare 6 Spare 40% 40% 75% 40% 75% 40% Spare 7 55% 25% 55% 25% 55% 55% 25% 25% 8 40% 65% 40% 40% 40% 65% 40% 15% 40% 9 55% 25% 40% 40% 15% 40% 40% 25% 55% 10 40% 55% 25% 25% 55% 40% 11 40% 55% 25% 25% 55% 40% 12 55% 25% 40% 40% 15% 40% 40% 25% 55% 13 40% 65% 40% 40% 40% 65% 40% 15% 40% 14 55% 25% 55% 25% 55% 55% 25% 25% 15 65% 40% 65% spare Spare 40% 75% 40%

(22) Table 4 below summarizes the results of experiment 2. Each value in the table corresponds to the yield of tomatoes on the tomato plants (weight of fruit only=tomato yield)

(23) TABLE-US-00004 TABLE 4 Summary of the results from experiment 2. The average yield is a result of several measurements on plots with the same irrigation conditions. 100% 85% 60% 35% 20% ETM ETM ETM ETM ETM With No With No With No With No With No flakes flakes flakes flakes flakes flakes flakes flakes flakes flakes Average 85.7 42.0 50.2 36.3 41.3 31.7 31.8 23.7 24.1 17.3 Yield (T/ha) Irrigation 603 603 500 500 399 399 248 248 202 202 (mm)

(24) FIG. 3 illustrates the effect of different water regimes on the yield of plants grown on soil with additions of polyurethane flakes compared to the yield of plants grown on soil without additions of polyurethane flakes. In other words, this graph indicates that when using the same amount of watering (100% ETM) an increase of yield of approximately 200% could be achieved when adding flakes into the soil. When adding the flakes according to the present invention to soil a drop of watering of 60% ETM and a similar yield could be achieved compared to the reference soil without addition of flakes (whereby the soil without addition of flakes had a watering of 100% ETM).

Experiment 3: Effect of Addition of Polyurethane Flakes to Soil on the Yield of Olives on Olives Trees

(25) FIG. 4 illustrates the results of the effect of adding polyurethane flakes according to the invention to the soil on the yield of olives.

(26) Additions of 20 volume % polyurethane flakes according to the invention to soil (calculated as volume flakes/volume flakes+soil) results in optimal yields (giving the highest number of olives). An amount of 20 volume % polyurethane flakes seems to stimulate the production of olives, a maximum number of olives was achieved with amounts of 20 volume % polyurethane flakes in soil while bigger fruit (but smaller amount) was achieved with amounts of 30 volume % polyurethane flakes in soil.