Methods to enhance soil water infiltration and to reduce soil water repellency using a surfactant composition

Abstract

A method of enhancing soil water infiltration (SWI) and/or reducing soil water repellency (SWR) comprising: treating an area of groundcover with a composition A comprising A1) a block polymer (P) comprising at least one polyethyleneoxide moiety and at least one polypropyleneoxide moiety, and A2) an alcohol alkoxylate (E), wherein the SWI of the area of groundcover is enhanced and/or the SWR of the area of groundcover is reduced after treatment with the composition A.

Claims

1. A method of enhancing soil water infiltration (SWI) and/or reducing soil water repellency (SWR) comprising: treating an area of groundcover with a composition (composition A) comprising A1) a block polymer (P) comprising A1.1) a (EO-PO-EO) triblock polymer of a general formula (Q1):
HO(CH.sub.2—CH.sub.2O).sub.f—[CH(CH.sub.3)—CH.sub.2O].sub.g—(CH.sub.2—CH.sub.2O).sub.h—H  (Q1) wherein f, g and h independently are 1 to 100 to denote a degree of polymerization and thus determine molecular weight, and A1.2) a (EO-PO-EO-PO-EO) pentablock polymer of a general formula (Q2)
HO(CH.sub.2—CH.sub.2O).sub.a—[CH(CH.sub.3)—CH.sub.2O].sub.b—(CH.sub.2—CH.sub.2O).sub.c—[CH(CH.sub.3)—CH.sub.2O].sub.d—(CH.sub.2—CH.sub.2O).sub.e—H  (Q2) wherein a, b, c, d and e independently are 1 to 100 to denote a degree of polymerization and thus determine molecular weight; and A2) an alcohol alkoxylate (E) based on 2-propylheptanol, wherein a wt.-% ratio of A1) to A2) is adapted such that the SWI of the area of groundcover is enhanced or the SWR of the area of groundcover is reduced after treatment with the composition A.

2. The method according to claim 1, wherein the block polymer (P) has a surface tension of 33 to 47 mN/m at a concentration of 1 g/L in water at 23° C. as measured according to DIN 53914.

3. The A method according to claim 1, wherein the composition A comprises 40 wt.-% to 60 wt.-% of block polymer (P), or wherein the composition A comprises 40 wt.-% to 60 wt.-% of alcohol alkoxylate (E), based on the total weight of the composition A.

Description

(1) Experimental Details

(2) Synthesis of the Alcohol Alkoxylate (E1)

(3) 158.2 g (1.0 mol) 2-Propylheptanol isomer mixture and 1.5 g of potassium hydroxide as alkoxylation catalyst were introduced into an autoclave. After a dehydration phase followed by inertisation with nitrogen, 228.8 g of ethylene oxide (corresponding to 5.2 mol) were passed in continuously at 145 to 155° C. To complete the reaction, stirring was continued for 1 hour at the same temperature. The temperature was then lowered to 125 to 135° C. and 272.6 g of propylene oxide (corresponding to 4.7 mol) were passed in continuously. To complete the reaction, stirring was continued for 5 hour at the same temperature. Then the temperature was raised to 145 to 155° C. and 101.2 g of ethylene oxide (corresponding to 2.3 mol) were passed in continuously. To complete the reaction, stirring was continued for 1 hour at the same temperature. The reaction product was neutralized with acetic acid at 80° C. to a pH of 6 to 7.

(4) The product (E1) had the following properties:

(5) Hydroxyl number (DIN 53240, phthalic anhydride method): Approx. 72 mg KOH/g

(6) Molecular weight (calculated based on the hydroxyl number): approx. 770

(7) Viscosity (EN 12092, 23° C., Brookfield, 60 rpm): approx. 130 mPa*s

(8) Wetting power (EN 1772, 1 g/l in distilled water with 2 g/l soda ash at 23° C.): 17 sec

(9) Foam formation (EN 12728, 40° C., 2 g/l in water with 1.8 mmol Ca.sup.2+-Ions/l, after 30 sec): 15 ml

(10) Surface tension (DIN 53914, 1 g/l in distilled water at 23° C.): 28.2 mN/m

(11) In the Tables, Examples and Figures below, this product (E1) is also referred to as “E”.

(12) Synthesis of the Block Polymer (P1)

(13) 116.8 g (0.2 mol) Polypropylene glycol with average molecular weight of 600 g/mol, 58.4 g (0.6 mol) diethylene glycol and 4.4 g of potassium hydroxide, as alkoxylation catalyst, were introduced into an autoclave. After a dehydration phase followed by inertisation with nitrogen, 1236 g of propylene oxide (corresponding to 21.2 mol) were passed in continuously at 125 to 135° C. The temperature was then increased to 145 to 155° C. and 584 g of ethylene oxide (corresponding to 13.3 mol) were passed in continuously. To complete the reaction, stirring was continued for 1 hour at the same temperature. Phosphoric acid was added to the reaction product at 80 to 90° C. and water was distilled off to precipitate K.sub.xH.sub.3-xPO4. The neutral product was obtained after filtration with a pH of 6 to 7. (P1) contains (EO-PO-EO) triblock polymer of the general formula (Q1) and (EO-PO-EO-PO-EO) pentablock polymer of the general formula (Q2) in a ratio of 1:3.

(14) The product (P1) had the following properties:

(15) Hydroxyl number (DIN 53240, phthalic anhydride method): Approx. 45 mg KOH/g

(16) Molecular weight (calculated based on the hydroxyl number): approx. 2500

(17) Viscosity (EN 12092, 23° C., Brookfield, 60 rpm): approx. 500 mPa*s

(18) Wetting power (EN 1772, 1 g/l in distilled water with 2 g/l soda ash at 23° C.): >300 sec

(19) Foam formation (EN 12728, 40° C., 2 g/l in water with 1.8 mmol Ca.sup.2+-Ions/l, after 30 sec): 0 ml

(20) Surface tension (DIN 53914, 1 g/l in distilled water at 23° C.): 39.2 mN/m

(21) In the Tables, Examples and Figures below, this product (P1) is also referred to as “P”.

(22) Synthesis of the Block Polymer (P2)

(23) EO(6)/PO(34)/EO(6)—Triblock Copolymer

(24) 600 g (1.0 mol) Polypropyleneglycol with average molecular weight of 600 g/mol, and 6 g of potassium hydroxide, as alkoxylation catalyst, were introduced into an autoclave. After a dehydration phase followed by inertisation with nitrogen, 1400 g of propylene oxide (corresponding to 24.1 mol) were passed in continuously at 125 to 135° C. The temperature was then increased to 145 to 155° C. and 500 g of ethylene oxide (corresponding to 11.4 mol) were passed in continuously. To complete the reaction, stirring was continued for 1 hour at the same temperature. Phosphoric acid was added to the reaction product at 80 to 90° C. and water was distilled off to precipitate K.sub.xH.sub.3-xPO4. The neutral product was obtained after filtration with a pH of 6 to 7.

(25) The product (P2) had the following properties:

(26) Hydroxyl number (DIN 53240, phthalic anhydride method): Approx. 45 mg KOH/g

(27) Molecular weight (calculated based on the hydroxyl number): approx. 2500

(28) Viscosity (EN 12092, 23° C., Brookfield, 60 rpm): approx. 400 mPa*s

(29) Draves wetting (seconds, 25° C., 1% concentration): 10

(30) Foam formation (Ross Miles, 0.1% concentration, mm): 25

(31) Surface tension (DIN 53914, 1 g/l in distilled water at 25° C.): 42.8 mN/m

(32) Synthesis of the Alcohol Ethoxylate (L1)

(33) i-Tridecanol (Basis: Trimeric Butene)+8EO

(34) 700 g of i-tridecanol (corresponding to 3.5 mol) together with 4.0 g of potassium hydroxide as alkoxylation catalyst were introduced into an autoclave. After a dehydration phase followed by inertisation with nitrogen, 1232 g of ethylene oxide (corresponding to 28.0 mol) were passed in continuously at 110 to 120° C. To complete the reaction, stirring was continued for 1 hour at the same temperature. The reaction product was neutralized with acetic acid at 80° C. to a pH of 6 to 7.

(35) The product (L1) had the following properties:

(36) Hydroxyl number (DIN 53240, phthalic anhydride method): Approx. 95 mg KOH/g

(37) Molecular weight (calculated based on the hydroxyl number): approx. 590

(38) Viscosity (EN 12092, 23° C., Brookfield, 60 rpm): approx. 150 mPa*s

(39) Wetting power (EN 1772, 1 g/l in distilled water with 2 g/l soda ash at 23° C.): 25 sec

(40) Foam formation (EN 12728, 40° C., 2 g/l in water with 1.8 mmol Ca.sup.2+-Ions/l, after 30 sec): 550 ml

(41) Surface tension (DIN 53914, 1 g/l in distilled water at 23° C.): 28.0 mN/m

(42) In the Tables, Examples and Figures below, this product (L1) is also referred to as “L”.

(43) Experimental Description of the Experiments with Soils:

(44) Various water repellent soils from Western Australia, Australia, with different degrees of water repellency as indicated by differences in the MED values according to Roy and McGill (2002) were tested. In each case the 0 to 5 cm top soil was used. In Table 1 both main soil characteristics and their locations are indicated.

(45) TABLE-US-00001 TABLE 1 Location and characteristics of soils (n.d. = not determined): Organic Soil pH pH Soil texture Carbon MED code (CaCl.sub.2) (H.sub.2O) % sand % silt % clay (%) value Soil location S1 5.2 n.d. 85.9 3.2 10.9 2.9 2.4 WA134 S2 5.5 n.d. 93.4 1.0 5.6 2.0 4.0 WA177 S3 5.6 6.1 94.4 2.5 3.1 0.8 1.0-2.0 Meckering S4 5.4 6.0 97.5 0.5 2.0 1.0 4.0 South Stirling S5 5.0 6.0 86.1 6.4 7.5 4.9 2.7 York S6 4.6 5.5 95.7 1.2 3.1 0.5 2.0-3.0 Strathalbyn

(46) Protocol (Methods for the Soil-Related Experiments):

(47) The protocol adopted consisted of precisely packed glass columns with diameter 10 mm of target soils with particle diameters less than 420 μm and packed to a consistent density with ±0.05 variation. All soils were pre-dried at 40° C. prior to packing. Surfactants were applied to the top of the column as solutions at a rate corresponding to 2 L/ha as a banded application which translates to 17-20 L/ha in blanket application, which was then left 1 hr followed by water applied which corresponded to a 5 mm (rain event). This allowed the surfactants to infiltrate and distribute further. Soil columns were then allowed to dry at 40° C. to regain their initial weight. Water infiltration tests were then carried out at a constant hydraulic head of 5 mm. Infiltration distance and water retention (mass change) were then determined as a function of time. Finally, the hydraulic conductivity was estimated from the drainage rate at constant hydraulic head. The range of soil types were selected to cover MED values (see Roy and McGill, 2002) from 1.0 (moderately low hydrophobicity) to 4.0 (very severe hydrophobicity).

(48) The infiltration rates measured for all soil samples were replicated in either independent duplicate or triplicate runs. The reproducibility of all data fell within the variation ±0.05 to ±0.25 cm for infiltration depths up 10 cm.

(49) Testing: Infiltration testing comprised comparisons between (1) (N) no surfactant—water wetting, (2) P treated, (3) E treated, and (4) P-E blend, including limited L replacing P surfactant, and L-E blends. Application rates for both surfactant and surfactant blends were maintained at a constant mass basis of 2L/ha equivalent where the compositional ratio in the blend was 1:1.

(50) Results are expressed as % reduction in infiltration time to reach a depth of 3 cm (corresponding to the seed depth) and 6 cm (corresponding to initiation of the developing rhizosphere), where % reduction is with respect to the wetting under no surfactant conditions.

(51) Results of water holding capacity (pore filling) are expressed in terms of water holding capacity given as retained water in terms of % of the soil saturation capacity (based on pore density of the packed soil bed). Data compared are at a depth of 8 cm which is within the developing root zone, and where seed depth is 3-4 cm and which includes the reported times for infiltration i.e., 3 cm and 6 cm.

(52) Abbreviations in Tables and Figures

(53) TABLE-US-00002 Soil code Soil location S1 WA134 S2 WA177 S3 Meckering S4 South Stirling S5 York S6 Strathalbyn

(54) P=Block polymer (P1)

(55) L=Alcohol ethoxylate (L1)

(56) E=Alcohol alkoxylate (E1)

(57) P-E=Composition comprising 50 wt.-% block polymer (P1) and 50 wt.-% alcohol alkoxylate (E1)

(58) L-E=Composition comprising 50 wt.-% alcohol ethoxylate (L1) and 50 wt.-% alcohol alkoxylate (E1)

(59) N=No Surfactant

(60) D=Depth in cm

(61) T=Time in seconds

(62) MED=Molarity of Ethanol Droplet

(63) Results on Water Repellent Soils a) Block polymer (P1)+Alcohol alkoxylate (E1):Water infiltration time

(64) TABLE-US-00003 TABLE 2 Reduction in time required for water to infiltrate to 30 mm depth compared to untreated soil Treatment P E P-E Soil code MED % reduction % reduction % reduction S1 2.4 −38.2 −89.7 70.1 S5 2.6 95.4 72.2 98.1 S4 4.0 77.3 91.1 99.2 S3 1.0-2.0 72.0 34.0 81.0 S6 2.0-3.0 88.0 77.0 94.3

(65) TABLE-US-00004 TABLE 3 Reduction in time required for water to infiltrate to 60 mm depth compared to untreated soil Treatment P E P-E Soil code MED % reduction % reduction % reduction S1 2.4 −29.6 −128.6 63.3 S5 2.6 85.9 43.5 90.6 S4 4.0 54.3 78.9 96.5 S3 1.0-2.0 21.0 −5.6 73.0 S6 2.0-3.0 64.4 60.0 83.3 b) Block polymer (P1)+Alcohol alkoxylate (E1):Water holding capacity

(66) TABLE-US-00005 TABLE 4 Surfactant Moisture content as a % of Treatment soil saturation capacity Soil code MED N P E P-E S4.sup.A 4.0 ~0 14.4 22.5 42.5 S3.sup.B 1.0-2.0 16.3 31.3 30.0 48.0 .sup.AAfter 138 s when the wetting front reaches a depth of 8 cm in the P-E pre-applied S4 soil .sup.BAfter 274 s when the wetting front reaches a depth of 8 cm in the P-E pre-applied S3 soil c) Alcohol ethoxylate (L1)+Alcohol alkoxylate (E1):Water infiltration time

(67) TABLE-US-00006 TABLE 5 Reduction in time required for water to infiltrate to 30 mm depth compared to untreated soil Treatment L E L-E Soil code MED % reduction % reduction % reduction S5 2.6 73.1 72.7 97.3 S4 4.0 94.0 94.0 99.2 S2 4.0 92.0 81.0 92.0

(68) TABLE-US-00007 TABLE 6 Reduction in time required for water to infiltrate to 60 mm depth compared to untreated soil Treatment L E L-E Soil code MED % reduction % reduction % reduction S5 2.6 63.3 43.6 90.2 S4 4.0 83.5 85.8 96.7 S2 4.0 71.5 68.0 80.6

(69) It is expected that (P2) has the same effect on the above water-holding capacity and water infiltration time as (P1).

(70) The above experiments, especially in the Tables (Tables 1 to 6) and Figures (FIG. 1 to 8) show that the SWI could be enhanced and the SWR could be reduced by applying the tested surfactant compositions to specific soils.

(71) Field Trial Experiments

(72) The following field trial experiments have been conducted (results of the field trials see Table 7):

(73) Experimental Design

(74) TABLE-US-00008 Study design Complete Randomised Block Replications 5 Plot length (m) 12 Plot width sprayed (m) 1.8

(75) Site Details

(76) TABLE-US-00009 Country Australia, Western Australia Location Kojonup Soil description Gravelly Sand Previous crop Canola

(77) Crop and Sowing Details

(78) TABLE-US-00010 Crop type Barley Variety La Trobe Seeding rate 75 kg/ha (kg/ha) Tillage type Minimum tillage Cultivation Nil Seed bed Un-Tilled, Grazed Stubble loading <5% Sowing equipment Knife points and press wheels Sowing speed 4.8 (km/hr) Sowing depth 2 Fertiliser applied Pre-emergent 50 kg/ha Urea 100 kg/ha Gusto Gold Post-emergent 30 L/ha UAN 40 L/ha UAN

(79) Further crop protection agents have been applied pre-emergent and post-emergent.

(80) Application Details

(81) Liquid In-Furrow

(82) In-Furrow treatments were applied via a liquid injection system during seeding. The in-furrow injecting hose is located immediately behind the fertilizer chute on the seeding type assembly. The surface banding assembly is located immediately behind the press-wheel, with liquid treatments place at the base of the furrow. A diaphragm pump was used to propel the treatments at a pressure of 1.3 bar. All treatments were applied at 4 km/hr and a total application volume 100 L per hectare. At this speed and application volume a constant stream of liquid is achieved. The application rate of the surfactant [(P1) only] and the surfactant combination [50 wt.-% (P1) and 50 wt.-% (E1)] tested was 2 L per hectare in 100 L water per hectare.

(83) Assessment Data Scoring Systems

(84) Crop Establishment

(85) The number of seedlings emerged from 5 individual 1 meter rows were counted, and converted to plants/m.sup.2 based on 25.4 cm row spacing.

(86) Crop Phytotoxicity

(87) A visual subjective percentage (%) score was given for each plot based on any symptoms of crop phytotoxicity observed such as chlorosis, tipping and scorch, where 0=no crop phytotoxicity and 100=full crop death.

(88) Yield

(89) Plots were harvested with a Haldrup trial header and the weights in kg/plot recorded, then converted to t/ha using measured plot dimensions.

(90) Results of the Field Trials

(91) TABLE-US-00011 TABLE 7 Results of the field trials Crop establishment Yield in % of (Emergence Yield in tons Standard the yield of counts) in Crop per hectare deviation of untreated plants/m.sup.2 Phytotoxicity (mean value) the yield control Untreated control 92 0 5.649 0.366 100.0 Treatment with 109 0 5.904 0.781 104.5 surfactant (P1) (not only (application significant) rate: 2 L/ha) Treatment with 119 0 6.292 0.602 111.4 the surfactant (P < 0.01 combination student t- comprising 50 wt.- distribution) % (P1) and 50 wt.-% (E1) (application rate: 2 L/ha)

(92) Table 7 shows that in the field trials, the treatment with the surfactant combination comprising 50 wt.-% (P1) and 50 wt.-% (E1) is superior to both the untreated control and to the treatment with surfactant (P1) only.