Illinois
Fertilizer Conference Proceedings
January 25-27, 1999
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K.D Smiciklas1 and
A.S. Moore2
Lake Bloomington is a major source of drinking water for area residents of Bloomington, IL, and has a history of nitrate (NO3-N) concentrations that exceed 10 ppm. Drinking water with greater than 10 ppm NO3-N consumed by infants under the age of six months can induce a fatal disorder known as methemoglobinemia (blue baby syndrome). Lake Bloomington was created in 1929 with a surface area of 572 acres, and it depends primarily on surface water from two tributaries (Money and Hickory creeks) to maintain water volume. The Lake Bloomington watershed consists of approximately 43,100 acres, of which 86% is row cropped with corn or soybean, 4% is pasture, 5% is wooded, and 5% is contained in water or urban areas. The McLean County Extension Service, McLean County Soil and Water Conservation District, the Natural Resource Conservation Service of McLean County, Illinois State University, and the City of Bloomington have formed a cooperative group to address the water quality problem of Lake Bloomington.
Nitrogen (N) fertilizers are necessary for profitable corn production, but there is concern that excessive rates of N fertilizer may have adverse effects on groundwater quality (Schepers et al., 1991). As environmental and human health concerns about N fertilizer use intensify, the importance of proper N management is becoming more critical. Keeney and DeLuca (1993) noted that relatively high NO3-N concentrations of certain surface waters of Iowa can be attributed to N fertilizers (both synthetic and organic sources) and intensive agricultural practices such as the installation of tiles to drain farmland. Of particular concern is the agricultural producers who over-apply N fertilizer in excess of what the crop can utilize, thus increasing the potential of N leaching into groundwater supplies (Schepers et al., 1991). The rate of N application, and not the source (as synthetic fertilizer or manure), was the most important determinant of the potential for NO3-N leaching in corn (Patni and Colley, 1989). Other nonagricultural sources of NO3-N include suburban land use via septic system effluent (Gold et al., 1990) and naturally occurring N release from soil organic matter in the spring (mineralization).
Many researchers have investigated means to reduce the potential of N loss from agricultural production systems, such as winter cover crops and lower fertilizer N rates (Staver and Brinsfield, 1990; Hubbard et al., 1991). A 1993-96 survey of people actively engaged in agricultural field crop production in the Lake Bloomington watershed found that the median N fertilizer application rate was 151-180 lbs N/acre, with an expected mean corn grain yield of 156 bu/acre (Smiciklas and Moore, 1997). Although lowering the application rate of N may help to alleviate NO3-N leaching, agricultural producers may risk substantial economic loss from lowered productivity (Roberts and Lighthall, 1991).
It has long been recognized that NO3-N may leach beneath the rooting zone of corn and move into shallow groundwater supplies (Wagner et al., 1976). The majority of the NO3-N may leach within 1.5 months after application, if rainfall exceeds 200 mm during this period (Hubbard et al., 1991). Nitrate-nitrogen may also leach in significant amounts during the winter and early spring periods, when plant growth and uptake of N is minimal (Owens, 1990). Thus, delaying fertilizer N application until the corn crop can efficiently utilize the N is one option that may help to reduce NO3-N leaching. Agricultural producers that apply fertilizer N after crop emergence may be able to decrease the potential of NO3-N leaching. Post-emergence N applications entail a greater degree of risk, because weather may prevent timely application during the critical stages of corn growth. Therefore, many agricultural producers have chosen to apply fertilizer N in the spring before planting. This increases the likelihood of NO3-N leaching, particularly in seasons with excessive moisture.
One objective of this study is to quantify sources of NO3-N in water that enters Lake Bloomington. The second objective of this study is to elucidate the influence of fertilizer N management upon subsequent water quality. The knowledge gained from this study will aid in developing recommendations that deal with fertility and cultural practices that promote the safe stewardship of Illinois farmland, while maintaining high-quality drinking water.
Beginning in 1993, various sites within the Lake Bloomington watershed have been monitored for NO3-N concentration on a weekly basis. These sites include tiles that drain native woodland/pastures, agricultural production fields, and organic production fields. In addition, surface water runoff, rainwater, and creek water has also been sampled at three-mile increments. A yearly survey to ascertain the productivity, timing, rate, and form of N fertilizers by agricultural producers in the watershed has also been conducted.
To elucidate the impact of fertilizer N practices upon water quality, a 30-acre site has been selected (Hoffman farm, Hudson, IL; farmed by Mr. Larry Troyer, Hudson, IL) with the assistance of Mr. James Rutherford, an NRCS soil conservationist from McLean County, IL. The site has been subdivided into six equal parcels of approximately 5 acres. Within each 5-acre parcel, 4-inch tile was installed in April 1997 on a 75-foot grid with interceptor access to collect tile water on a weekly basis for NO3-N concentration. For each parcel, automated monitors have been installed to record water flow and to sample water for NO3-N concentration from each rainfall that caused water flow within the tile. Six agricultural fertilizer N practices for corn have been evaluated (one treatment per parcel):
Soybean was grown in the first year of this experiment (1997) to allow the establishment of fertilizer N treatments in the fall of 1997. The second year (1998) has been devoted to corn production, utilizing the six treatments listed above. In the fall of 1997, the fall agricultural N treatments for corn were applied using an N rate monitor to ensure accurate application. In the spring and summer of 1998, the other N treatments were applied. The corn hybrid NK770Bt was planted in late April 1998 and harvested at a population of 28,500 plants/acre. At physiological maturity (R6 growth stage), four plants from each plot were removed and separated into leaves, stalk, and the grain. Dry weight and nutrient concentration and content were estimated as detailed by Smiciklas and Below (1992). Grain yield was measured by harvesting the entire plot (approximately 5 acres) with a commercial combine, and weighing the grain from each plot. By measuring NO3-N release into tile water and the N content of the plant, we hope to estimate an overall "N budget" for corn growth and productivity for Midwestern soils. Utilizing data collected from this experiment will help to elucidate when excessive NO3 is released from corn and soybean production, and if the timing or method of fertilizer N application can minimize NO3 leaching into Lake Bloomington.
Weekly sampling of water for NO3-N concentration within the Lake Bloomington watershed has been conducted from 1993 to present (Table 1 and Figure 1). The data indicates that row-crop agriculture releases excessive NO3-N into tile lines that drain into Money Creek and, subsequently, Lake Bloomington. Based on the comparison of water from a wooded pasture tile and water from row-crop agricultural tiles (organic and "conventional"), it would appear that row-crop agriculture plays a major role in the release of NO3-N into water that feeds into Lake Bloomington (Table 1). The second phase of the study (field N tile study at the Hoffman farm) will help determine if the release of excessive NO3-N from agriculture can be minimized by corn N fertility management.
A yearly survey to ascertain N management practices of agricultural producers in the watershed has also been conducted. The survey was sent to all landowners and tenants who farmed within the watershed, and the average response rate over the five-year period was 35%. The 1993-97 mean expected corn yield was 157 bu/acre, and a median N fertilizer application rate was 151180 lbs N/acre, which is within current University recommendations. In addition to N rate, the timing of N fertilizer application may have an impact on NO3-N leaching. On average, 51 % of fertilizer N in the watershed was applied in the fall, 35% in the spring before planting, and 14% after planting in the spring. Our data indicates that a large majority of the NO3-N leached into Lake Bloomington in the late spring to mid-summer (March-July); thus, fall applications of fertilizer N may be partially responsible for the elevated NO3-N levels in spring tilewater. These results need to be verified over a number of years to assess seasonal variability patterns. It is hoped that the knowledge gained from this cooperative work group will aid in developing strategies to protect the quality of water in Lake Bloomington.
The impact of the six corn fertilizer N practices upon water quality was evaluated at the Hoffman farm in Hudson, IL in 1997-98. The application of fall-applied N (anhydrous ammonia) resulted in tile water that contained 58% more NO3-N, as compared to the same rate of fertilizer N applied in the spring (Figure 2). The addition of N-Serve (a nitrification inhibitor) decreased NO3-N concentration in tile water by 9%, compared to the same rate of fertilizer N applied in the fall without N-Serve. Even with the use of N-Serve, fall-applied N losses (as measured by NO3-N concentration in tile water) greatly exceed the recognized hazard level established by the federal government of 10 ppm. As expected, the treatment with the lowest concentration of NO3-N in the tile water was the control (no fertilizer N), followed by the other spring and sidedressed N applications. Despite increased NO3-N concentrations in the tile water, the fall-applied N treatments (with and without N-Serve) produced approximately the same grain yield as the full rate pre-plant spring application (Table 2). The full rate pre-plant spring application contained 25%n more plant N, as compared to the fall-applied treatment with N-Serve (Table 3). Overall, the application of anhydrous ammonia in the spring produced equivalent grain yields to that of the fall-applied treatments, while reducing NO3-N release into tile water. This reduction could be due to many factors, one of which was the increased plant N accumulation of the spring-applied treatment. Thus, one method of reducing the NO3-N in water entering Lake Bloomington is to encourage the application of fertilizer N in the spring. These results need to be verified over a number of years to assess seasonal variability patterns.
The use of N fertilizer in Illinois corn production is widespread because it is required for plant growth, and most soils do not have sufficient capacity to supply N. The importance of proper N management as it relates to yield is becoming more critical as environmental concerns about excessive N fertilization intensify. One objective of this study is to quantify sources of NO3-N in water that enters Lake Bloomington. Beginning in 1993, 36 sites within the Lake Bloomington watershed have been monitored for NO3-N concentration on a weekly basis. The 1993-98 average NO3-N concentration for the following sources within the watershed was: water from rain (1.1 ppm), surface water runoff (6.5 ppm), wooded pasture tile (1.3 ppm), organic production tile (9.4 ppm), agricultural production tiles (17.1 ppm), and subsequent creek water (12.0 ppm). In addition, as creek water passed through small municipalities, its NO3-N concentration dropped an average of 0.7 ppm. A yearly survey to ascertain N management practices of agricultural producers in the watershed has also been conducted. The 1993-97 mean expected corn yield was 157 bu/acre, and a median N fertilizer application rate was 151-180 lbs N/acre. In addition to N rate, the timing of N fertilizer application may have an impact on NO3-N leaching. On average, 51 % of fertilizer N in the watershed was applied in the fall, 35% in the spring before planting, and 14% after planting in the spring.
The second phase of this study is to elucidate the influence of fertilizer N management upon subsequent water quality. Six agricultural fertilizer N management techniques have been monitored for NO3-N release via tile and surface drainage. Overall, the application of anhydrous ammonia in the spring produced equivalent grain yields to that of the fall-applied treatments, while reducing NO3-N release into tile water. This reduction could be due to many factors, one of which was the increased plant N accumulation of the spring-applied treatment. The knowledge gained from this study will aid in developing recommendations that deal with fertility and cultural practices that promote the safe stewardship of Illinois farmland, while maintaining high quality drinking water.
1 Associate Professor of Plant Science, Department of Agriculture, Illinois State University, Normal IL and Adjunct Associate Professor of Crop Science, Department of Crop Sciences, University of Illinois-Urbana.
2 Associate Professor of Agriculture, Department of Agriculture, Illinois State University, Normal IL.
Gold, A.J., W.R. DeRagon, W.M. Sullivan, and J.L. Lemunyon. 1990. Nitrate-nitrogen losses to groundwater from rural and suburban land uses. J. Soil Water Conserv. 45:305-310.
Hubbard, R.K., R.A. Leonard, and A.W. Johnson. 1991. Nitrate transport on a sandy coastal plain soil underlain by plinthite. Trans. ASAE 34:802-808.
Keeney, D.R., and T.H. DeLuca. 1993. Des Moines river nitrate in relation to watershed agricultural practices: 1945 versus 1980s. J. Environ. Qual. 22:267-272.
Owens, L.B. 1990. Nitrate-nitrogen concentrations in percolate from lysimeters planted in a legume-grass mixture. J. Environ. Qual. 19:131-135
Patni, N.K., and L.B. Culley. 1989. Corn silage yield, shallow groundwater quality and soil properties under different methods and times of manure application. Trans. ASAE 32:2123-2128.
Roberts, R.S., and D.R. Lighthall. 1991. The political economy of agriculture, ground water quality management, and agricultural research. Water Resour. Res. 27:437-446.
Schepers, LS., M.G. Moravek, E.E. Alberts, and K.D. Frank. 1991. Maize production impacts on groundwater quality. J. Environ. Qual. 20:12-16.
Smiciklas, K.D., and F.E. Below. 1992. Role of nitrogen form in determining yield of field grown maize. Crop Sci. 32:1220-1225.
Smiciklas, K.D., and A.S. Moore. 1997. Patterns of Nitrogen Use by Producers in the Lake Bloomington Watershed. Agron. Abstracts, p. 38.
Staver, K.W., and R.B. Brinsfield. 1990. Patterns of soil nitrate availability in corn production systems: implications for reducing groundwater contamination. J. Soil Water Conserv. 45:318-323.
Wagner, G.H., K.F. Steele, H.C. MacDonald, and T.L. Coughlin. 1976. Water quality as related to linear, rock chemistry and rain water chemistry in a rural carbonate terrain. J. Environ. Qual. 5:444-451.
