trogen haven't an opportunity to develop to the extent that they now do in conventional combustion systems, Mr. Evans explains. (In practice, the oxides of nitrogen are controlled by lowering the peak temperature at which the fuel burns in the cylinder. One way to achieve this is to run the fuel mixture rich and recirculate portions of the exhaust gas.) The concept of precombustion isn't a new one, says Mr. Evans, whose entire professional career has centered on the building of auto and aircraft engines. Numerous automotive engineers have looked into it from time to time over the past 30 years or so. He attributes the failure of the idea from reaching fruition to flaws in engineering design which he contends he has overcome satisfactorily during the four years he and his associates have worked on the problem. Scavenge. The auto and oil industries are spending sizable sums annually to bring down the level of noxious gases in auto emissions. Their approach in the main is to develop systems that scavenge these gases from the exhaust before they get into the atmosphere. The advances that have been achieved in this direction have brought emissions down considerably from a few years ago, when the average car was emitting some 1000 p.p.m. of hydrocarbons, 3.5% carbon monoxide, and 1500 p.p.m. nitrogen oxides. Last month, a number of advanced-concept vehicles were shown to President Nixon's quality control panel at San Clémente, Calif. These vehicles were all designed for emission levels substantially below present and proposed regulatory requirements. Mr. Evans and physicist Karl Morghen, who played an important role in helping perfect the Azure Blue system, cite some impressive data when discussing the gaseous makeup of exhaust emanating from an auto engine that uses the device. Hydrocarbon content, expressed as hexane, rarely exceeds 10 p.p.m. Carbon monoxide content, they claim, is so small that it can't be measured precisely. Oxides of nitrogen concentration range between 35 and 37 p.p.m. The new system allegedly results in a cooler-running engine so that crankcase oil should maintain its quality over a longer period. And the exhaust gases contain enough oxygen to support combustion of the crankcase gases at an appropriate point in the hot exhaust manifold. Another factor of the Azure Blue system ("the name reflects our desire to restore the sky to its healthy blue appearance") is that it can be built into the production of new gasoline engines with a minimum of retooling. All thafs involved is the fitting of a
cylinder head—or a pair of heads in the case of V-8 engines—that includes a composite assembly made up of a dual ratio carburetor and a dual ratio induction manifold. Retrofit. But how about the 97 million registered automobiles that are on the roads today? These, too, can be adapted by installing the company's Betro-Mizer units—so called because the units can be retrofitted and they are misers on gas. These include a spark plug of novel design in which the rich fuel mixture feeds in through the body of the plug. Ignition takes place in a precombustion chamber that's part of each plug. A pair of orifices directs the resulting flame into the main chamber in a fanlike pattern, through the center of which a jet "lance" protrudes. As plans now stand, Azure Blue
will have its Retro-Mizer kits on the market early next year, retailing for $65 each. Meanwhile, Mr. Evans is drawing up a licensing arrangement that will allow other companies to make the units on a royalty basis. The exhaust emission values that Mr. Evans propounds were garnered from a seven-mode test that Aerojet General Corp. in Sacramento made with a single-cylinder dynamometer. Within the coming weeks Mr. Evans expects to arrange for more extensive evaluations to be carried out at state and federal testing laboratories. Pending their outcome, the attitude of most automotive engineers toward the Azure Blue device will remain one of open skepticism, since multicylinder engines under field operating conditions generally give quite different values, they point out.
Fertilizers can add to water pollution But banning all fertilizer use would triple food prices, USDA soil expert contends M
FERTILIZER A N D COIL,
"There are three kinds of pollution: actual, political, and hysterical." Thus did Dr. Victor J. Kilmer, TVA soils and fertilizer research chief, kick open the symposium on "Fertilizer Use and Water Quality." Little is known about the effects of fertilizer use on water quality, and the nature and extent of the problem have not been defined, he says. "This must be done through well-planned research. Otherwise, restrictive legislation based on faulty and inconclusive evidence is bound to be passed." The urgency of getting factual data
was brought home by Dr. Frank G. Viets, Jr., chief soil scientist for USDA's soil and water conservation research division at Fort Collins, Colo. He answered the question: Will controlled fertilizer use be necessary? His answer: "The question means will it be essential to limit the rate of fertilizer a farmer applies under the framework of state laws to meet the federal requirements on water quality? It is a good question because some leading scientists, often not too familiar with the needs of agriculture, have called for total bans on the use of fertilizer. Bills have been introduced into state legislatures calling for limitations on the amount of fertilizer a farmer can apply." Application. The rate of fertilizer
Land use affects nitrate content of soil and subsurface water Surface type
Virgin grassland Dryland Irrigated land (except alfalfa) Irrigated land (alfalfa) Feed lots Source:
NO3 soil content, 20-foot profile (Pounds per acre)
NO3 content in percolated water at water table (p.p.m.) Range Mean
0.1-19 5-9.5 0-36
90 261 506
11.5
79
9.5
1-44
1,436
13.4
0-41
7.4
11.1
USDA, Fort C o l l i n s , Colo.
SEPT. 22, 1969 C&EN 73
application in the U.S. is now controlled voluntarily, although very imperfectly, he says, by the cost of materials and a system of soil testing unsurpassed in the world. Farmers are finding that too much fertilizer is unprofitable and that excessive amounts can reduce yields and quality. However, there are some fertilizer companies that overpromote high and excessive rates of application, he says. The situation has grown worse under the present oversupply condition in the U.S. market and the resulting price-cost squeeze. There is no argument that phosphate and nitrates in ground water cause eutrophication and, with nitrates, health problems, Dr. Viets says. "However, the antifertilizer interests point to the phenomenal increase in the use of phosphate and nitrogen fertilizers in the past three decades and infer that these must be major sources of the eutrophication and nitrate problems. Although it cannot be denied that there are instances where improper fertilizer use can be blamed, wholesale indictment of fertilizers cannot be justified." The usual approach to eutrophication studies is to assign certain inputs to identifiable industries, municipal sewage plants, washoff from storm sewers and rainfall, and to charge the rest by difference to agricultural runoff, he explains. In the last is animal waste flushed from feedlots, fields, and pastures; eroding soil; washout of nutrients from dead vegetation; and fertilizers either in solution or eroding sediment. Fertilizer is only one part of the agricultural picture. Price. Dr. Viets estimates that fertilizers are responsible for one third of the U.S/s food and fiber production. "To stop all fertilizer use would mean that on the average our food would at least triple in price," he points out. "In spite of all the interest in pollution control, recent polls indicate that the average citizen is not willing to pay much out of his pocket for control." Dr. Viets gave an example of the difficulty of getting direct evidence of underground pollution from fertilizer nitrate or other sources. Core holes were drilled in the South Platte Valley of Colorado under different kinds of land use. The cores and water that percolated into the core holes were sampled. Although the average amount of nitrate in 20-foot holes varied greatly, there was little difference in the nitrate of water. The virgin grassland and the dryland fields had never received nitrogen fertilizers. The irrigated cropland not in alfalfa received about 100 pounds of nitrogen per acre per year. The cattle feedlots got as much as 10 tons of organic and urea nitrogen 74 C&EN SEPT. 22, 1969
annually. The lands had been in the same kinds of use for more than 40 years, yet there was no correlation between the amount of nitrate in the soil and in the percolated water. Hazard. As the above illustration indicates, determining the source of nitrate in water is very difficult. However, it is also of prime importance because, among the fertilizers, nitrate is the only one designated a health hazard. The U.S. Public Health Service has established a maximum safe level of nitrates for drinking water because of possible injurious effects on infants and livestock, Dr. Lester T. Kurtz, professor of soil fertility at the University of Illinois, Urbana, says. Among the fertilizer elements, nitrate is unique, he points out. It is the element most needed by crops and added in the largest amounts of fertilizers. However, nitrogen, regardless of the ion species added to the soil, is converted to nitrate—the most mobile fertilizer element. This makes it subject to leaching. Leaching, though difficult to estimate, is often a major process in the fate of fertilizer nitrogen, Dr. Kurtz says. Hence, it can easily get into water supplies. However, because of variation of weather, differences in soils, and differing soil management practices, it is practically impossible to forecast the magnitude of leaching losses, he explains. Although rife with problems of changing variables, mathematical expressions for the movement of ions in soils are being developed. These will be useful for correlations with "real life" data, he says. Besides leaching, erosion can cause the removal of large quantities of nitrates as well as other nutrients, Dr. Kurtz says. As much as 15% of the nitrogen, applied 24 hours earlier in a simulated soil experiment, was carried away by runoff from the equivalent of a 5-inch rain. Skilled farmers can easily reduce this type of loss. Unfortunately, he says, erosion control is often neglected because the farmer feels that the purchase of fertility is more convenient. Nitrogen. Nitrogen is also lost from the soil in gaseous form by two methods. With ammonia or ammoniaforming fertilizers^ volatilization can occur, Dr. Kurtz explains. "Careful application of such fertilizers can eliminate this kind of loss." The second method of gaseous nitrogen loss is by dentrification, which is due to biological reduction of nitrate to N 2 0 and No, and perhaps also to NO and N 0 2 . The crop itself, of course, takes up most of the nitrogen fertilizer applied —if it is properly applied. However, if the plant stalks are not removed after harvest and replaced by a cover crop nitrogen is easily leached from
the stalk. When the soil has not yet thawed in the spring, the leached nitrogen can easily get into ground waters. The other element used in fertilizers that may cause pollution problems is phosphorus. Phosphorus is frequently the limiting factor in the growth of algae and aquatic weeds, Dr. Robert F. Holt, director of USDA's soil and water conservation research at Morris, Minn., explains. Although it is difficult to establish the exact threshold concentration for the phosphorus needed to support nuisance blooms of algae, he says, it is known that inorganic phosphorus concentrations above 0.01 p.p.m. and inorganic nitrogen concentrations of 0.30 p.p.m. can produce dense algal blooms in the spring. Unlike nitrogen, phosphorus cannot be leached from the soil. Phosphorus reacts with the soil and is immobile; therefore, it's almost impossible for it to enter ground water. However, it can enter surface waters by being attached to eroded soil. Whether or not this bound phosphorus, or some of it, is released to the surface water is not known. The eroded soil might remove dissolved phosphorus from the water, but it could also act as a reservoir of phosphorus when the concentration in the water is low and equilibrium between water and sediment is attained, Dr. Holt says. Dissolved phosphorus in runoff waters can easily occur when snow melts in the spring. At this time phosphorus is leached from plant stalks, he explains. This happens with or without adding fertilizer to the soil. Loss. The method of incorporating phosphate fertilizers into the soil does have an appreciable effect on the content of dissolved phosphorus in runoff waters, Dr. Holt points out. If the phosphate fertilizer is plowed under, the loss is minute because the phosphorus reacts quickly with the soil particles. As with nitrogen fertilizers, the largest individual potential source of phosphate to water supplied from agriculture is from animal wastes. With the present trend to larger feedlots which concentrate the animal waste sources, major emphasis should be placed on safe, efficient handling of these wastes, he says. The symposium members seemed to agree that judicious fertilizer use and good soil management will eliminate many of the possibilities of fertilizer contamination of water. They also pointed out that new methods of agricultural practice should be sought and tested. After all, the people who make their living from the environment have the greatest stake in its protection.
