8 



MISCELLANEOUS PUBLICATION NO. 10*65, U.S. DEPARTMENT OF AGRICULTURE 



move through the soil in the soluble state. Some of 

 this may be carried as complex organic molecules. 

 Surface runoff may well carry phosphate as part 

 of the suspended particles. Barnyard wastes may 

 carry 1,000 p.p.m. of phosphorus. Water in the 

 drains from fertilized fields in irrigated areas in 

 rare instances have been found to carry as much 

 as 1 p.p.m. of phosphate. 



Very little modern information is available on 

 the phosphorus content of runoff from soils vary- 

 ing in geochemical characteristics, treatments with 

 chemical amendments and fertilizers, cultural 

 practices, and hydrologic conditions. 



Far more study is needed on methods of deter- 

 mining phosphorus content of water in terms of 

 biological significance. Total phosphorus values 

 are meaningless. We ought to be able to distin- 

 guish four different states of phosphorus in water 

 samples: (a) That which is in true solution as or- 

 thophosphate ; (b) that which is in solution in a 

 nonpolar form as an organic polyelectrolyte ; (c) 

 that which is adsorbed on suspensoids; and (d) 

 that which is a component part of the mineral of 

 suspensoids. 



In view of the widespread concern over eutroph- 

 ication of surface waters, a major effort should 

 be launched as rapidly as possible to attain evi- 

 dence as to the cause and effect sequence. Even on 

 large bodies of water such as Lake Erie, there is 

 frequent accusation that use of fertilizer on farm- 

 ers' fields is the causative source. The dearth of ac- 

 curately accrued quantitative and qualitative in- 

 formation on phosphorus in runoff water from the 

 land does little to allay argument. 



Nitrate in Ground Water 



Xitrate in drinking water can cause methemo- 

 globinemia in babies — "blue babies.'" It is also toxic 

 to livestock. The biochemical status of a baby's 

 stomach readily reduces nitrate to nitrite, as does 

 that of a ruminant. Thus, one hears of nitrate in 

 well waters causing "blue babies" or nitrate poison- 

 ing in ruminants. Cases of "blue babies'' associated 

 with nitrate in well waters have been reported in 

 the Middle West. 



When nitrate is found in ground water, the 

 sources may be several — sewage or septic tank 

 effluent, feedlots or barnyards, field fertilization, 

 or the natural accumulations such as found in the 

 caliche of semiarid regions. The Public Health 

 Service Standards (125) specify that the nitrate- 



nitrogen content of drinking water should not ex- 

 ceed 10 p.p.m. 



Research evidence in Missouri indicates that vir- 

 tually none of the nitrate in ground water comes 

 from field fertilization. Evidence from a secluded 

 valley under concentrated study in California in- 

 dicates that sewage effluent and nitrification proc- 

 esses in the semiarid soils may be the main sources 

 of the rather high levels — 100 p.p.m. — of nitrate 

 found in the ground water. Studies in Hawaii on 

 high nitrate levels in the aquifer indicated that 

 nitrogen fertilization of irrigated sugarcane fields 

 may be the source. 



The diversity of observations and conclusions 

 with respect to nitrate from various sources mov- 

 ing into ground water indicates the need for better 

 information that may be gained by expanded field 

 studies. The degree to which nitrite may be asso- 

 ciated with nitrate during downward percolation 

 needs careful study. The very modest level of re- 

 search in this area needs to be increased appreci- 

 ably to gain reliable answers to pressing questions. 



Inorganic Salts and Minerals 



This category includes neutral inorganic salts, 

 mineral acids, and fine suspended metal or metal 

 compounds. These substances enter into streams or 

 onto soil from the effluent of various smelting, 

 metallurgical, and chemical industries; from 

 drainage from mines: and from natural sources. 

 Industrial sources of these chemicals are com- 

 paratively minor in relation to total dissolved 

 solids carried by the Nation's streams. 



The Public Health Service estimated in the early 

 1930's that 2.7 million tons of sulfuric acid were 

 produced annually by mines and delivered into 

 tributary streams. Although the amount of acid 

 delivery from mines has decreased, awareness of 

 the problem has increased. Acid mine drainage 

 kills fish and spoils water for domestic, livestock, 

 irrigation, and recreation uses. Agriculture and 

 forestry have an interest in the elimination of this 

 problem. 



Salts normally present in the soils and geologic 

 materials of arid regions move into streams and 

 onto irrigated farms. Colorado River water at 

 Yuma, Ariz., carries about 1.2 tons of salt per 

 acre- foot. Average annual flow of the Colorado at 

 Hoover Dam is about 15 million acre-feet annually. 

 At this location, the river transports more than 



