Mechanical Snake River Undisturbed Soil Core Sampler

A power-driven undisturbed soil core sampler was designed to obtain undisturbed soil cores from a much greater depth than the original hand-operated sampler

Suspended organic matter removal from aqueous extracts of high pH soils

In order to pursue the sodic soil reclamation research. it was necessary to develop a pretreatment method for sodic soil extracts that would simultaneously remove the HCO ion and suspended organic matter interferences without adding additional interferences

Sampling Ports for an Instrumented Lysimeter System

An improved method for mounting ceramic-moisture sampling cups and soil-atmosphere sampling tubes in lysimeters is described. The 0.31-m diam by 1.18-m deep lysimeters were constructed from low pressure polyvinyl chloride irrigation pipe (PVC) and contained soil 1.0-m deep. Tensiometer tubes with attached cups, and open-ended pyrex gas sampling tubes were installed at three depths, using sealing ports in the lysimeter walls. The sealing ports were constructed from half of a PVC pipe compression coupler. This system allows for inserting the sampling cups and tubes after the soil has been added and settled. The sampling equipment can also be removed before the soil is sampled and removed when studies are completed. Individual sampling units can also be removed for cleaning or repair during the study without disrupting lysimeter operation. This was not possible with earlier described lysimeter systems

The CaCO3-CO2-H2O system in soils

Equations used to develop the CO2-Ca-pH relationships in calcareous soils are reviewed. The equation PCO2(Ca) = (H)2 Kc, is used to draw a three-dimensional surface and to derive three partial differential equations to illustrate the relationships between CO2 partial pressure, Ca activity and pH. Kc is a combination of Henry's Law constant, the first and second dissociation constants for carbonic acid and the calcite solubility product. The three dimensional CO2-Ca-pH surface illustrates how the three parameters relate to each other under ideal conditions. The partial differential equations are presented to illustrate how changes in one parameter affect the other two. The CO2-Ca-pH surface provides a graphical method for introducing the idea of three component equilibria, while the partial differential equations provide a mathematical representation of these interactions for those with chemical thermodynamics or strong mathematic or modeling backgrounds. Deviations from this ideal model in natural systems are discussed for those who wish to extend the discussion to natural systems

Reclamation and Reuse of Irrigation Sediments

IRRIGATION canals and drainage ditches often require periodic cleaning to remove wind-blown or water-deposited sediments. Ponds used to trap sediment from irrigation runoff and food processing wastewater also require periodic cleaning if they are to remain effective. The freshly removed sediment is usually piled next to the canals or ponds for drying and temporary storage. Dredge materials often are stored near the source until the piles become so large they constitute a nuisance. Removal then is necessary. Sediment piles frequently remain in place for 10 years or more

Sodic Calcareous Soil Reclamation as Affected by Different Amendments and Crops

Sodium leaching efficiencies (moles of Na removed per unit leachate volume) were measured and compared from four noncropped and four cropped treatments applied in duplicate to 1.0 m deep sodic calcareous silt loam in lysimeters. Treatments included a check, gypsum, chopped alfalfa (Medicago saliva L), fresh manure, alfalfa, sorghum (Sorghum bicolor), sudan grass (Sorghum sudanese) hybrid (which will be called sorghum hybrid for simplicity), sorghum hybrid + leaching, and cotton (Gossypium hirsutum L). The sorghum hybrid + leaching treatment soil was leached with tap water until 0.5 pore volume of leachate was collected from lysimeter bottoms, and then sorghum hybrid was planted. Sorghum hybrid was the most efficient treatment in reclaiming Na-affected soil. All four noncropped soils eventually became dispersed in the lower part of the profile and hydraulic conductivity became very low. Cropped treatments continued to conduct water at a satisfactory rate for reclamation; however, due to low water use, cotton treatment produced a low total Na removal. Sorghum hybrid shows promise as a crop that could be used to speed reclamation of sodic calcareous soils. The treatments producing the highest sodium removal efficiencies also produced the highest soil atmosphere CO2 concentrations. By selecting crops, amendments, and water application rates and timing, calcareous sodic soil reclamation can very likely be accomplished faster and more economically than in the past

Solute transport and reactions in salt-affected soils

Modeling solute transport and reactions in salt- and sodium-affected soils can be considered as three simultaneous processes: (i) solute transport; (ii) precipitation-dissolution reactions; and (iii) cation exchange. Solute transport is the physical movement of ions by convective transport (water transport) and ion dispersion within the solvent system (due to concentration gradients). Precipitation-dissolution reactions are dominated by carbonate or lime and gypsum reactions. Mineral weathering reactions are important in special cases, but are not considered here. Cation exchange models usually consider only calcium (Ca), magnesium (Mg), and sodium (Na) exchange on the negatively charged soil surfaces. However, in some cases it may be necessary to consider potassium (K) exchange if K constitutes a substantial portion of the solute or exchangeable ions. These three processes will be discussed separately and will be presented as separate subroutines that can be called by water flow and plant growth models similar to that described in Ch. 11

Fluoride Adsorption by a Saline Sodic Soil Irrigated with a High F Water

Langmuir isotherm data for F adsorption were obtained from 1 : 10 soil : water extracts of soil samples from a lysimeter study. A sodic silt loam surface soil with a saline sodic subsoil was irrigated with a high sodium chloride, high fluoride (0.38 mMF) geothermal well water. A previous study showed that fluorite (CaF2) was precipitated from solution in the upper portion of this profile while another mechanism removed F solution in the lower part of the profile to below 0.02 mMF. The Langmuir isotherm data indicate that one kind of surfaces or sites remove fluoride from solution over the 0 to 1.1 to 1.2 mMF range. The adsorption capacity for this F removal is about 4.4 to 5.8 mmol F/kg of soil and the equilibrium constant is between 0.54 to 1.00 l/mmol F. Once these surfaces or sites were saturated, a second kind of sites removed F from solution, and had an adsorption capacity of 9.2 to 11.4 mmol/kg and an equilibrium constant of 0.16 to 0.27 l/mmol. Both data sets fit the Langmuir equation. At some point before or after this second set of sites or surfaces was saturated, the fluorite ion activity product was exceeded and fluoride was then removed from solution via fluorite precipitation. The two adsorption mechanisms lowered the soil solution F concentration sufficiently to prevent ground water contamination, but once the adsorption sites were saturated, fluorite precipitation does not decrease F concentration sufficiently to meet drinking water standards

Use of Amendments to Reduce Water Requirements for Stand Establishment of Small-Seeded Crops

Soil crusting after planting is a serious problem in stand establishment of small-seeded crops in the Southwest. When crusting occurs in a saline, warm soil, stand establishment problems are especially severe. It is customary to use costly irrigation water to keep seedbed surfaces moist after planting to reduce soil crusting and to lower soil temperatures. Phosphoric acid (24% and 12%) and sulfuric acid (95%) were evaluated to determine their effectiveness in reducing soil crusting and reducing the amount of water required to obtain stands of sugarbeets, alfalfa, wheat and barley. Phosphoric acid, applied in 4-6 cm bands over the seed row at planting and before irrigation, reduced crusting and increased sugarbeet and alfalfa seedling emergence. Emerged seedlings from phosphoric acid treated plots were larger and one irrigation (10-15 ha cm/ha) was saved in stand establishment. Sulfuric acid applied in bands reduced soil crusting. Soluble salts in the seed zone resulting from band application of sulfuric acid killed or damaged seedlings. Sulfuric acid, when applied in irrigation water to saline-sodic soils, improved plant growth and water use efficiency

Plant Nutrients in Potato Processing Waste Water Used for Irrigation

Food processing industries discharge large volumes of waste water that are generally characterized by high organic matter content, large amounts of suspended solids, and various inorganic constituents including nitrogen, phosphorus, and potassium (3, 4, 5, 6). Until recently, food processing waste water was discharged into streams or rivers, but governmental regulations now prohibit this. Food processors must either treat their waste water to meet established water quality standards before discharging it, or find an alternative waste water disposal method. Secondary treatment, although expensive, has been satisfactory in some cases, but tertiary treatment with removal of nitrogen and phosphorus may be required in the future. Energy requirements for secondary treatment are high, and plant nutrients usually contained in the waste water are a valuable resource. Irrigating cropped agricultural land requires little energy and some of the nutrients can be used by growing plants. Therefore, irrigating with food processing waste water may be a long-term solution to the waste water disposal problem. This report gives the nitrogen, phosphorus, and potassium concentrations in potato processing waste water and the amounts of water and included nutrients applied to fields at five potato processing plants in Idaho