62 



MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE 



and the South Carolina agricultural experiment 

 station involving the fate of plant nutrients added 

 to Lakeland sand in lysimeters is especially perti- 

 nent. Lysimeter No. 16 grew no crop and received 

 no nitrogenous fertilizer except the 25 pounds of 

 nitrogen per acre received in rainfall over a 5-year 

 period. Nitrogen recovered in the percolate totaled 

 153.9 pounds for the 5 years. One could only hy- 

 pothesize that nitrogen was being mineralized in 

 this fallow soil, and readily being leached out in 

 the absence of growing crops. 



Lysimeters Nos. 19, 20, 21, and 22, each received 

 679.1 pounds of total nitrogen over the 5-year 

 period as fertilizer, manure, and rainfall additions. 

 Millet was grown on each of these lysimeters. 

 Nitrogen in the leachate from these four lysimeters 

 averaged 18.1 pounds for the 5-year period. It 

 would be difficult to conclude from this experi- 

 ment that adding fertilizer to a cropped field con- 

 tributed to the nitrogen found in the percolate 

 moving downward to the ground water. 



Lysimeter studies were carried out at Cornell 

 University using a Dunkirk silty clay loam and 

 growing timothy grass continuously for 8 years. 

 In one set of treatments, the annual nitrogen ad- 

 ditions in pounds per acre were 93, 124, 155, and 

 217 ; and the annual nitrogen losses in the leachates 

 were 0.2, 0.2, 0.3, and 1.9 pounds, respectively. 

 These nitrogen losses to deep percolation under 

 grass cover were amazingly small. 



The Kentucky agricultural experiment station 

 carried out a lysimeter experiment for 11 years 

 using Maury silt loam that received no nitrogen 

 fertilizer. Various forage crops were grown. The 

 average annual nitrogen losses in the leachates, in 

 pounds per acre, from the various cropping treat- 

 ments were as follows : uncropped 74, Korean les- 

 pedeza 58, alfalfa 9, and bluegrass 5. Kind of 

 cover may have a tremendous effect on deep perco- 

 lation of nitrogen even though no chemical is 

 applied to the soil. 



Cooperative research between the U.S. Depart- 

 ment of Agriculture and Purdue University (74) 

 has shown that appreciable nitrogen losses can oc- 

 cur in surface runoff if ammonium nitrate is broad- 

 cast over the surface of both fallow and sod before 

 a runoff-producing storm. 



Since the advent of high analysis fertilizers in 

 the 1930's, considerable research has gone into 

 designing fertilizer applicators on planting equip- 



ment so that the more concentrated fertilizers will 

 not "burn" the germinating seed, the fertilizer ap- 

 plied will be protected from runoff losses, and the 

 minerals will be placed where they will be maxi- 

 mally utilized by the growing crop. The California 

 Agricultural Experiment Station studied the ni- 

 trogen and phosphorus contents in tile drainage 

 effluent from irrigated areas in the San Joaquin 

 Valley (63). The amount of phosphorus entering 

 the drains was insignificant. The nitrogen content 

 of the drainage effluent varied from 1.8 to 62.4 

 p.p.m. One area under study during 1962 consisted 

 of 150 acres in cotton and rice that had received ap- 

 plication of 23,500 pounds of nitrogen. Assay of 

 the drainage water indicated that 14,800 pounds of 

 nitrogen were lost in the drains. That is, 63 percent 

 of the nitrogen applied went down the drain. This 

 finding is important in that it shows that there 

 may be plenty of room for improvement in effi- 

 ciency in nitrogen use under irrigation. 



Research in Hawaii (85) has provided evidence 

 that water in an aquifer under an irrigated sugar 

 plantation receiving up to 300 pounds of nitrogen 

 per acre over a 2-year period may have an appre- 

 ciably elevated nitrate content. 



The University of Missouri has made extensive 

 studies to explain the high nitrate content in cer- 

 tain crop plants and in numerous samples of 

 ground water. The research findings indicated that 

 leachates from feedlots were the main source of 

 nitrate (or nitrite) in most contaminated aquifers. 

 The studies revealed that fertilizer nitrogen has 

 been of little importance in water contamination, 

 but could become important in the future. These 

 studies are being continued. 



It has been known for many years that certain 

 well waters in California contain 100 p.p.m. of 

 nitrate or more, and that many of them contain 

 more than 10 p.p.m. One well near Riverside, which 

 yields water containing about 100 p.p.m. of nitrate, 

 has been used as a source of irrigation water for 

 over 30 years without material change in nitrate 

 content (66). The University of California has 

 research underway to ascertain the sources of ni- 

 trate found in California wells. 7 Special attention 

 is being given to the 10-square-mile basin occupied 

 by Grover City and Arroyo Grande. This basin 



' Stout, P. R., and Burau, R. Extent and Significance 

 of Fertilizer Buildup in Soils. Presented at Anier. Assoc. 

 Adv. Sci. Symposium, Washington, D.C., Dec. 29. 1966 



