Water & Solute Movement A solid, liquid, or gas that is dissolved in a liquid to make a solution. When the solute has an electrical charge, the mobility of the solute is affected

Soil Properties & Water Movement Infiltration The ability of water to move into the soil from the soil surface Permeability The ability of water to move through the soil horizon after it has penetrated the surface Is controlled by its least permeable horizon

Soil Properties & Water Movement Solute movement is affected by pH OM CEC Soil texture Soil structure

Soil Properties & Water Movement Soil pH influences the solubility and ionic state of a solute and thus influences its mobility OM can absorb and adsorb many times its own weight, tying up solutes with the notable exception of K, thus reducing their mobility CEC reflects the number of binding sites available for a positively charged solute to bind to

Soil Properties & Water Movement Soil texture: Finer textured soils usually have a higher CEC and less movement of solutes Soil Structure: Well-structured soils allow for more movement of solutes down into the soil profile Reduces the risk of runoff Increases the chance of solute movement into a shallow water supply

Soil Properties & Water Movement Other factors that affect solute movement: Timing Rate of application Tillage Conservation practices Irrigation

Soil Properties & Water Movement Timing of a solute applied close to time of crop use has less time for excessive movement. Rates of application above what is needed for crop production can lead to excessive leaching, runoff, or residual. Tillage promotes good infiltration and reduces runoff potential

Soil Properties & Water Movement Tillage (contd) Breaks up non-permeable zones Improves water use Conservation practices, like terracing, strip cropping, etc.. all trap water and soil particles and thus, the dissolved and retained solutes. Irrigation can increase solute leaching

Nutrient Movement in the Soil & Water Non-Point Source Pollution: Cannot be traced to a specific location point or time of entry. Ag chemicals from field runoff Nitrate movement into ground water Point Source Pollution: Entry into the environment can be traced to a single event or sequence of events at an inclusive location Chemical spill at a well head Fertilizer spill into a storm sewer

Plant & Water Relationships Evapotranspiration (ET): The loss of water from the soil by both surface evaporation and plant transpiration Is influenced by stage of crop growth, water status, and soil water potential As the crop grows, evaporation tends to decrease and transpiration increases As the soil water decreases, more energy is required to remove water from the soil

Plant & Water Relationships Wind Increases evaporation losses Increases transpiration losses to a point…. Temperature works the same way wind does Warm air can hold more water (humidity) than cold air Solar radiation (sunlight) eventually becomes heat energy

Plant & Water Relationships Relative humidity A measure of the concentration of water vapor in the air The higher the Relative Humidity the less likely there will be a need for supplemental water

Plant & Water Relationships Plant canopy Reduces soil evaporation but increases transpiration Evapotranspiration is not proportional to the amount of size of plant canopy, but does trend higher as the plant canopy expands

Plant & Water Relationships How plants lose water Stomata on leaf surfaces Stomata open and close according to temperature, humidity, wind, and soil water supply 98% of the water transpired is used to cool the plant

Plant & Water Relationships Excessive soil moisture Reduces nutrient availability Reduces oxygen availability for root growth Roots can begin to die within 48 hours Denitrification in water-logged soils can account for major nitrogen losses

Plant & Water Relationships Soil Moisture Deficiency Plant requires more energy to move water Affects nutrient movement & uptake N movement by mass flow K movement by mass flow & diffusion P movement by diffusion

Water Holding Capacity Type Available Water (in/ft) Course sand 0.25 to 0.75 Fine sand 0.75 to 1.00 Loamy sand 1.10 to 1.20 Sandy loam 1.25 to 1.40 Fine sandy loam 1.50 to 2.00 Silt loam 2.00 to 2.50 Silty clay loam 1.80 to 2.00 Silty clay 1.50 to 1.70 Clay 1.20 to 1.50

Available Water Handout

Permeability Classification System

The Hydrologic Cycle

Water Quality Concerns Ground water contamination Surface water contamination Nitrate can contaminate both Nitrate reported in two ways Nitrate NO3- 45 ppm (or mg/l) Nitrate-N NO3-N 10 ppm (or mg/l)

Water Quality Health affects of nitrate in drinking water Methemoglobinemia (Blue Baby Syndrome) which is the result of poor O2 transport in the blood of very young babies Formation of nitrosamines, known carcinogens that form when nitrates react with organic compounds

Water Quality Water Contamination Occurs often at well heads Considered a point-source pollutant Can enter through cracked casings, improper seals, or ponded contaminants near well head Sources of information about drinking water standards: US EPA, State Public Health and Environmental Agencies

Water Quality Prevention of water contamination Use anti-backsiphoning devices Never fill or dump pesticides or fertilizers near a well head Fill depressional areas around a well head

Sediments & Surface Water Quality Sediments settle out of the water stream As the flow of the water slows In reduced water temperature Sediments are considered pollutants The sediment itself Contaminants bound to the sediment Phosphorus contamination is primarily through sediment contamination (organic P exception)

P and N Effects on Surface Water Quality Causes eutrophication where algae and weeds flourish Eutrophic waters have High nutrient levels Low species diversity Low dissolved oxygen Poor taste and odor Excessive vegetation (slows flow and….) Can be turbid and cause fish kills

Preventing Surface Water Contamination Filter/buffer strips Plant along surface water shores Slows water movement and causes sediment to drop out before entering the main body of water Riparian Areas or Tree Plantings Serves the same purpose as above Both methods are effective in using up nitrates and phosphorus.