The growing trend of mandating the use of nonpotable or recycled water on golf courses is now commonplace throughout the United States. Golf courses are now the leading recreational turfgrass user of wastewater. When used over an extended period of time, the soil’s physical characteristics will change as the soil assumes many characteristics of the irrigation source. The use of effluent or reclaimed water can be problematic if levels of sodium and/or carbonate salts dominate these soil profiles. Frequent evaluation of the effluent water properties and those of the soil are required if the golf course superintendent intends to successfully manage the these challenges of alternate water irrigation.

Calcium and magnesium serve important roles in turf production and play a key role in maintaining the structural integrity of clay-containing soils. Both of these multi-valent cations are considered essential to soil permeability. Without sufficient levels of Ca and Mg, the ability of water, oxygen and roots to move within the soil macropores is impeded. Calcium also displaces the weaker sodium cation from soil particles, where it is leached from the rootzone by rainfall or irrigation events.

Clay aggregates are constructions of plate-like particles stacked together. The surface of the clay particle is dominated by negative charges and would normally repel each other. However, the double-valence Ca and Mg elements flocculate, or “bridge” the clay particles. One positive charge attaches to the negative charge of one clay particle (neutralizing the site) and the open positive charge attracts to the negative charge of another clay particle. The divalent Ca and Mg cations allow the plates to approach each other more closely than monovalent cations which allows them to bind together (flocculate) into domains and eventually for aggregates.

Irrigation Water Problems

Sodium. Sodium exists in nearly all irrigation water. At elevated levels (levels where Na ions are more than 15% of the exchangeable sodium percentage), Na ions replace Ca ions. Because the Na ions have smaller electric charges than Ca ions, they are adsorbed less coherently to the surface of the clay particle. When the soil particle are wetted, the hydrated radius of the Na ions force the clay platelets apart (swelling) and weaken the attractive forces. This process essentially destroys the structural units resulting in deflocculation and particle dispersion.

Soil Physical Structure and Permeability

SOIL RECLAMATION PROGRAM

Illustration showing disassociation of clay aggregates and platelets.

IRRIGATION AND SOIL WATER ACIDIFIER

PRODUCT APPLICATIONUSE GUIDE

In sandy soils, clay colloids can move in the soil solution and plug pore chan-nels at pore interfaces.

Carbonates. Carbonates greatly complicate the management of excessive Na. If bicarbonate ion levels exceed 150 ppm (> 150 mg/L, respectively), they will react with calcium and magnesium in the soil to form insoluble calcium car-bonate and magnesium carbonate that precipitate from the soil solution. This leaves excess soluble Na to replace Ca or Mg on CEC sites – creating conditions for sodic soil development.

When water containing carbonates collect and dry at the soil surface, Ca and Mg carbonate deposits are formed (crusts) that inhibit infiltration of water into the soil profile. Furthermore, the deposits fill up the pore space between particles and greatly reduce the saturated hydraulic conductivity and air-filled porosity of the soil profile.

For soils that aren’t calcareous and have a limited ability to supply their own soluble calcium, the initial use of calcium amendments is a common recom-mendation for soils with depleted calcium (Ca2+) and magnesium (Mg2+) levels and high sodium (Na+) levels.

However, in many sodic soils, poor water penetration and blocked pores due to build-ups of calcium carbonate and magnesium carbonate are insufficient to leach Na in the form of NaSO4. Under these conditions, it is recommended that pHAcid initially be applied to the soil as a surface spray first, followed by routine injection of pHAcid through the injection system.

Graphic depiction of plugged pore channel by colloidal clay partices and organic matter.

Reclamation of Carbonate andSodium-Affected Soils

In order to maintain water movement that will allow for optimum penetration, infiltration, and movement of water through the soil profile and allow leaching of excess salts from the soil, the use of REVERT soil surfactant on a monthly basis is highly recommended.

Before making any amendment decisions ensure that your soil and irrigation water quality analysis is conducted by an accredited, reputable laboratory.

pHAcid is a unique combination of a blend of acidifying agents combined with a multi-purpose, high molecular weight surfactant. This combination of complimentary technologies is designed to be applied either through a tank spray or through the irrigation system to provide the superintendent with a proactive approach to:

• Dissolve calcium carbonate and magnesium carbonate salts on the surface (crusts) and in the soil profile

• Improve the ability of soil-applied Ca-based amendments to produce soluble Ca

• Flocculate dispersed colloidal-sized clay particles and reaggregate dis-persed particles.

• Neutralize the negative effects of high bicarbonate and carbonate levels in irrigation water and the soil solution

• Lower pH of irrigation water and soil water

• Maintain the solubility of Ca and Mg in irrigation and soil water

Of all the mineral constituents in irrigation water, bicarbonates and to a less extent carbonates are often underestimated in terms of their potential to synergize soil degradation and disrupt water movement through soils. Carbonates greatly complicate the management of excessive Na. Their reactions reduce the amount of free calcium and magnesium in soil, allowing sodium to displace calcium from the negatively-charged exchange sites on clay particles.

pHAcid acidifying agents. pHAcid is an innoxious, non-fuming and non-corrosive acidifier that is very easy to use and environmentally safe. The pHAcid formulation is ideally suited as a replacement for strong acids used to treat carbonate-affected soils.

The pHAcid acidifying agents help eliminate the threat by carbonates (CO2-3) and

bicarbonates (HCO3- ) that tie up calcium and magnesium, allowing: (a) Ca and Mg

in irrigation water to remain soluble so it can displace Na from soil sites , and (b) allowing soil applied amendments to be more efficient and effective in producing soluble calcium (versus being precipitated as lime or dolomite).

H+ (from pHAcid) + HCO3- (in water) → CO2 + H2O

This order of correction does not imply that soil amendments be abandoned. However, since the problem of sodium affected soils goes beyond correcting abnormal carbonate levels, using soil amendments containing calcium is usually required.

pHAcid Surfactant. The non-ionic, “triblock” surfactant used in pHAcid was chosen specifically for its ability to enhance infiltration, percolation and drainage characteristics of the soil profile. This facilitates the coverage of the pHAcid treatment as well as enhances the “leaching” of sodium and carbonate salts from the rootzone.

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IRRIGATION AND SOIL WATER ACIDIFIER

Graphic showing surfactant, dispersed clay platelets and calcium cations initiating reformation of clay flocs aided by “polymer bridges.”

RECLAMATION OF CARBONATE AND SODIUM-AFFECTED SOILS

“Polymer” bridges within colloidal environments can improve the rate of floccu-lation (versus particle attraction by random particle collisions), produce larger floc and strengthen the aggregates.

As soil particle dispersion is reversed, aggregates reform on and around the sand particle base. By pulling soil particles together into aggregates, macro-pores are created. By creating macropores, we allow for improvement in infiltra-tion, water movement and retention, drainage and air-to-water ratios.

Illustration of surfactant, dispersed clay platelets, organic matter and calcium cations reformed into new clay aggregate.

Graphic depiction of aggregate reformation on sand particles resulting in improved pore spacing.

This unique surfactant has also been placed into the pHAcid formulation due to its ability to form physical interparticle bridges that encourage dispersed clay platelets and organic matter to merge and initiate reformation of clay flocs and multi-particle aggregates.

RECLAMATION OF SOILS AFFECTED BY WATER REPELLENCY AND WATER MOVEMENT PROBLEMS

Essentially all proven approaches to remediate carbonate and sodium-affected soils rely on the sufficient drainage to leach soluble sodium sulfate salts. However, as sand-based root zones mature, changes in the physical and chemical characteristics of the soil profile occur.

Soil Physical Characteristics. Following an 8-year USGA funded field study at the University of Nebraska’s John Seaton Anderson Turfgrass Research Facility, researchers reported that infiltration decreased by 70% for a 80 : 20 (80% sand: 20% sphagnum peat) profile and 74% for a 85 : 15 : 5 (85% sand : 15% sphagnum peat: 5% soil) profile as sand-based root zones matured. They attributed reductions in root zone infiltration to build-up of fine particles, fine particle migration and organic matter layering.

Organic Coatings. Throughout the aging process, highly managed turfgrass produce large quantities of soil organic matter (plant materials, humic substances, root exudates, thatch, and roots). Once subjected to microbial action, soil organic matter (SOM) becomes the primary source of problematic organic compounds that coat the surface of soil particles – a major cause of water repellency and non-uniform movement of water through the soil profile.

Water Repellency. Many scientists point to humic substances as an example of organic polymer materials that will adopt conformational changes in order to facilitate their adsorption to the soil particle interface and ultimately form non-polar (water repellent) films. As a result, the surface of the soil particle surface can quickly be covered with adjoining sequences of these adsorbed, non-polar polymer chains.

Development of water repellent organic coatings on soil particles is progressive in nature. As a result, these coatings exist as thin films on the particle surface (early stages of development) that progress to a layer-on-layer build up (“caking”) of water repellent organic substances during later stages of development.

Electron micrograph of wettable (hydrophilic) soil particle. Little humic substance is visible.

Electron micrograph of non-wettable (hydro-phobic) soil particle. Layer-on-layer deposition of humic substances is very visible.

The build-up of water repellent, non-polar organic coatings on mineral surfaces in the upper root zone has been identified by the general scientific community as the primary cause of soil hydrophobicity.

REVERT is a unique formulation of DEPRO1299, a blend of unique organic coating removal agents, combined with a best-in-class surfactant complex designed to provide the golf course superintendent with a broad, proactive approach to address the cause and problems associated with the build-up of organic coatings on soil particles and soil water repellency (SWR).

In REVERT’s SWR Management System, both its surfactant complex and its blend of organic coating removal agents (DEPRO1299) participate in the dissolution of hydrophobic organic coatings on particle surfaces – both early stage films and later stage polymer build up ( “caking”).

Layer-on-Layer Polymer Build up (“Caking”)

REVERT’s DEPRO1299 (removes) critical hydrogen atoms from areas on humic substances. Removal of the hydrogen atoms promotes structural decay. Deprotonation also increases the net negative charge on the humic substance molecules (increasing reactivity) that leads to layer separation and dissolution due to repulsive forces.

Particle Surface Film Coating

Organic coating removal agents in DEPRO1299. The organic coating removal agents found in DEPRO1299 also deprotonate (remove) hydrogen atoms at the organic coating – soil particle surface interface. As a result, the net negative charge of the humic substance is increased. Since most soil particles have a negative charge, both the surface and the humic substance repel each other. This begins the process of separating the humic film from the soil particle surface. The negative charge on the humic substance also makes it more water soluble.

SOIL MANAGEMENT SYSTEMFOR WATER REPELLENCY

SOIL PARTICLE SURFACE

adsorptionsite

adsorption site

HYDRPHOBIC HUMIC SUBSTANCEADSORBED TO SOIL PARTICLE SURFACE

Illustration depicting separation of humic substance layers following deprotonation by organic coating removal agents found in the REVERT formulation.

SOIL PARTICLE SURFACE

DEPROTONATED HUMIC SUBSTANCE LAYER

deprotonated functional groups

SIMILAR CHARGE REPULSION

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REVERTApply REVERT at 6 oz. per 1000 sq. ft. in 2 gallons of water. For best results, apply monthly throughout the growing season. No watering is required when used at recommended rates.

pHAcidThe initial application of pHAcid should be applied at 32 to 64 ounces per acre in a 1 to 2 gallon spray solution per 1000 sq. ft. Apply sufficient water to move product into the soil profile.

If a soil analysis shows carbonate levels at 150 ppm or less and/or sodium (Na) levels at less than 50 ppm, continue pHacid treatment throughout the growing season on a monthly basis at 32 ounces per acre in a 1 to 2 gallon spray solution per 1000 sq. ft. Apply sufficient water to move product into the soil profile.

If a soil analysis shows carbonate levels at 150 ppm or more and/or sodium (Na) levels at more than 50 ppm, continue pHacid treatment throughout the growing season on a 2-week basis at 32 to 64 ounces per acre in a 1 to 2 gallon spray solution per 1000 sq. ft. Apply sufficient water to move product into the soil profile.

Any soil receiving irrigation water with high sodium (Na) and bicarbonate levels should be amended with a soluble source of calcium in addition to the pHAcid spray program. In addition, irrigation water high in bicarbonates (> 1.5 - 2.0 meq/L (bicarbonate level = 90 - 120 ppm) should be amended with the pHAcid irrigation treatment schedule.

pHAcid Injectable irrigation water program:

1. Inject pHAcid at the rate of 1 gallon per 20,000 gallons of applied water every month if the RSC index of source water is more than 150 ppm (> 1.50 meq/L ).

2. Inject pHAcid at the rate of 1 gallon per 20,000 gallons of applied water every two weeks if the RSC index of source water is more than 250 ppm (> 2.5 meq/L ).

pHAcid treatments (in combination with soluble sources of calcium if needed) should be continued until sodium-affected soil levels are below hazardous levels.

Separation is completed as water molecules (attracted by REVERT’s surfactant complex “lift” the humic films/coatings and carry them out of the root zone.

The surfactant complex used in the REVERT formulation has an affinity for humic substances. They are included in the REVERT formulation to enhance the removal process by loosening and solubilizing the humic substances into the bulk solution as well as to facilitate the movement the coating removal agents in a uniform manner throughout the rootzone.

The surfactants also stay attached to humic substances that remain on the particle surface. Subsequent irrigations will rehydrate the surfactants and aid in additional removal of humic substances as well as contribute to a return of uniform patterns of infiltration, percolation, retention and favorable wetting patterns.

Unique Triblock Surfactant Complex. The amphiphilic nature of surfactants and humic substances can easily lead to their mutual attraction. The binding can be through either electrostatic or hydrophobic attraction. Surfactants in the REVERT formulation attach to hydrophobic fractions of the humic substances. As these surfactants attract water molecules (hydrate), they facilitate further separation of layered humic substance molecules. The surfactant complex also promotes transport into the bulk solution. This is often referred to as “flaking off” of the non-polar organic layers.

Where water repellent layers and film remain, REVERT’s surfactant complex is quick to establish sites for adsorption of water molecules – resulting in a return of uniform patterns of infiltration, improved percolation, retention and favorable wetting patterns.

SOIL PARTICLE SURFACE

DEPROTONATED HUMIC SUBSTANCE

SIMILAR CHARGEREPULSION

deprotonated functional groups

Illustration depicting separation of humic substance layer from soil particle surface following deprotonation by the DEPRO organic coating removal agents found in the REVERT formulation.

Graphic showing how surfactants in REVERT aid in the removal of hydrophobic humic substance from surface of soil particle by following deprotonation and initial separation from surface by organic coating removal agents.

SOIL RECLAMATION PROGRAM

When used on a monthly basis, it’s best-in-class non-ionic surfactants will overcome hydrophobic conditions and promote a consistent and effective pat-tern of hydration and re-hydration of the soil profile. Following its use in a well-designed rootzone management program, turfgrass managers should expect:

• Improved drainage • Relief from localized dry spots and water repellent soils• Uniform movement of water through the rootzone• Healthier roots and increased stress tolerance• Enhanced water use efficiency

The REVERT surfactant complex also contains a unique “triblock” surfactant that is capable of forming interparticle bridges that promote flocculation and aggregation of dispersed colloidal clay particles -- unblocking pores and creat-ing improved air-to-water ratios.

PROGRAM USE DIRECTIONS