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SPECIAL SUBMISSIONS
Findings from the USDA-sponsored Lake Erie Agricultural Systems for Environmental Quality Project

Trends in Agriculture in the LEASEQ Watersheds, 1975–1995

^a Water Quality Laboratory, Heidelberg College, 310 E. Market Street, Tiffin, OH 44883
^b School of Natural Resources, The Ohio State University, 2021 Coffey Road, Columbus, OH 43210-1085

* Corresponding author (Prichard{at}heidelberg.edu)

Received for publication August 12, 2000.

	ABSTRACT

TOP ABSTRACT INTRODUCTION METHODS RESULTS AND DISCUSSION SUMMARY AND CONCLUSIONS REFERENCES

 
County-level agricultural statistics were aggregated at the watershed level to provide estimates of trends in land use and agricultural management in the Maumee and Sandusky River watersheds during the period 1975–1995. Average farm size increased by 40% or more, but the number of farms decreased by nearly 40%; the total land area in agriculture also decreased, but only by about 7%. Conservation tillage increased from virtually nothing to nearly 50% of cropland in corn (Zea mays L.) and soybean [Glycine max (L.) Merr.]; most of the change is due to adoption of no-till soybean. The Conservation Reserve Program has enrolled more than 75000 hectares, but this represents less than 5% of total farmland. The great majority of land classified as highly erodible has been placed under treatment during the study period. Cropland in soybean has increased; land in wheat (Triticum aestivum L.) and hay has decreased. Cropland in corn has decreased in the Maumee watershed and increased slightly in the Sandusky watershed. Average per-hectare yields of corn, soybean, wheat, and hay have increased by 10 to 40%. Fertilizer phosphorus sales increased until about 1980 and have declined significantly since then; fertilizer nitrogen follows a similar but less pronounced pattern. The decreases are more substantial in the Maumee watershed than in the Sandusky. Manure use for fertilizer has also declined significantly.

Abbreviations: CRP, Conservation Reserve Program • LEASEQ, Lake Erie Agricultural Systems for Environmental Quality • LOWESS, locally weighted scatterplot smoother

	INTRODUCTION

TOP ABSTRACT INTRODUCTION METHODS RESULTS AND DISCUSSION SUMMARY AND CONCLUSIONS REFERENCES

 
ONE OF THE MAJOR GOALS of the Lake Erie Agricultural Systems for Environmental Quality (LEASEQ) program was to document changes in water quality in the Maumee and Sandusky Rivers and to determine to what extent trends in water quality were due to changes in agricultural land use and management practices. Several papers in this series address different aspects of the issue of water quality trends and their linkages to agricultural management practices (Richards and Baker, 2002; Moog and Whiting, 2002a,b; Baker and Richards, 2002). Forster and Rausch (2002) describe a number of governmental programs and other factors that have been instrumental in causing changes in agricultural practices.

The purpose of this paper is to describe various aspects of agricultural land use and management, and document changes that have occurred during the study period 1975–1995. As such, this paper presents important background information for many of the other papers in this series. Preliminary analyses of much of this information have been presented previously (Richards and Baker, 1998; Levison and Eckert, 1998; Eckert and Levison, 1999).

	METHODS

TOP ABSTRACT INTRODUCTION METHODS RESULTS AND DISCUSSION SUMMARY AND CONCLUSIONS REFERENCES

 
Aggregation of Agricultural Statistics
The agricultural statistics that are the background data for this paper are county-level estimates. For this study, we aggregated the county-level data into watershed estimates. Data values were missing for some counties in specific years; a few others appeared to be unreasonably large or small and were assumed to result from data entry or other operational errors. Missing values and outliers were replaced with values estimated from data from adjacent years. All nutrient parameters were expressed or reexpressed as quantities of elemental nitrogen (N) or phosphorus (P) to allow direct comparisons.

We assumed that each characteristic was uniformly distributed in each county, and estimated the watershed quantity for each county by multiplying the county quantity by the percent of the county that falls in the watershed upstream of the water quality sampling point. (The assumption of uniform distribution is undoubtedly not perfectly valid, but it is necessitated by the fact that most of the data are only available at the county level of resolution. Generalized land use maps show that agricultural and forested lands are well distributed within the counties that lie along watershed boundaries, and no major urban areas lie along the watershed boundaries within the study area, with the exception of Fort Wayne, Indiana. These observations suggest that the assumption of uniform distribution is unlikely to introduce serious errors into the analysis.)

Watershed totals were calculated as the sums of these adjusted county-level quantities. Watershed averages (e.g., per-hectare yields) were calculated from watershed totals, not from separate county averages. We chose to aggregate to the watershed upstream from the water quality sampling point rather than the entire watershed, so that areas reflected in the water quality observations and the agricultural statistics would be identical. The counties that were aggregated for the Maumee and Sandusky River watersheds are listed in Table 1, together with the percent of each county that lies upstream of the water quality sampling station.

Trend Analysis
In most cases, these parameters change rather slowly and linearly over time, and are not subject to extreme annual fluctuations, a welcome contrast to water quality data. When the general trend of data appeared linear, simple linear regression was used to describe trends quantitatively. When trends were clearly nonlinear, LOWESS smooths (Cleveland, 1979) were used to describe trends. The percent change over the period of record was calculated from the initial and final values determined from the regression equation or from the smooths of the LOWESS fit. Some parameters increased initially and then declined; for these a percent change from the maximum value was also calculated.

Several parameters reflected the success of programs that were not in operation at the start of the period of record (e.g., the Conservation Reserve Program). For such parameters, a percent change cannot be calculated because the initial value is zero. These parameters were summarized using the percent of eligible land treated at the end of the study period.

	RESULTS AND DISCUSSION

TOP ABSTRACT INTRODUCTION METHODS RESULTS AND DISCUSSION SUMMARY AND CONCLUSIONS REFERENCES

 
Many changes are apparent in agriculture over this 21-yr period. These changes are summarized in Tables 2 and 3, and displayed in Fig. 1 through 8 . In the discussion below, directions of change are presented without regard to whether the change is statistically significant. The level of statistical significance associated with each trend is indicated in Table 2 or 3.

View larger version (38K): [in this window] [in a new window]   Fig. 1. Trends in farmland, number of farms, and average farm size, 1976–1995.

View larger version (34K): [in this window] [in a new window]   Fig. 8. Trends in manure production, 1975–1995.

View larger version (61K): [in this window] [in a new window]   Fig. 2. Trends in conservation tillage, 1980–1995. (NT: no-till, MT: mulch-till.)

View larger version (45K): [in this window] [in a new window]   Fig. 3. Trends in enrollment in the Conservation Reserve Program (CRP). The long bar indicates the number of farm acres in a given year, scaled to fit by dividing by 10. In the Maumee basin in 1995, for example, CRP hectares were 5.1% of all farm hectares.

View larger version (53K): [in this window] [in a new window]   Fig. 4. Trends in application of treatment to highly erodible land.

View larger version (41K): [in this window] [in a new window]   Fig. 5. Trends in hectares devoted to corn, soybean, wheat, and hay, 1976–1995.

View larger version (40K): [in this window] [in a new window]   Fig. 6. Trends in yields per hectare for corn, soybean, wheat, and hay, 1976–1995.

View larger version (35K): [in this window] [in a new window]   Fig. 7. Trends in fertilizer sales, 1971–1995.

Several important conservation programs and practices have been introduced or adopted in a significant way during the study period. All were essentially absent at the beginning of the study period. Conservation tillage adoption began in the late 1980s, and by 1995 nearly half of the corn and soybean in the Maumee and Sandusky watersheds was farmed with conservation tillage (Fig. 2). The most important practice is no-till soybean. Conservation tillage with corn has proven to more problematic, and farmers have been less willing to adopt it. Adoption of conservation tillage appears to have reached a plateau, and further adoption may have to await changes in farm economics or development of new crop strains or new technologies.

The Conservation Reserve Program is designed to remove highly erodible land from production. Enrollment began in 1988; contracts are for 10 yr. Enrollment in CRP (Fig. 3) increased from 0 to 3% (Sandusky) or 5% (Maumee) of total farmland during the study period. Total enrollment in the two watersheds exceeded 75000 hectares in 1995. The number of hectares defined as highly erodible has increased in some counties and decreased in others, due to changes in criteria for eligibility and to revised evaluations of some fields. Most highly erodible land (85% in the Maumee watershed, 97% in the Sandusky) is reported to be receiving treatment, in accordance with a conservation plan, to reduce erosion (Fig. 4). However, no tracking is being done to verify that conservation plans are continuing to be followed. Thus, the indications of success in treating highly erodible land may be exaggerated.

Crop Patterns
The four main crops grown in the study area are soybean, corn, wheat, and hay. The typical full crop rotation is corn–soybean–wheat, but wheat is often skipped for economic reasons. Cropland planted to soybean has been increasing steadily in each watershed; the increase has been more substantial in the Sandusky watershed than in the Maumee (Table 2). Cropland planted to wheat and hay has decreased (Fig. 5). The decrease in wheat is greater in percentage terms, but fewer hectares have been planted in hay than wheat throughout the study period. Cropland in corn has decreased by more than 10% in the Maumee watershed, but increased by about 5% in the Sandusky watershed.

Yields for all four crops (Fig. 6) have increased on a per-hectare basis, reflecting better varieties, increased soil fertility, and better farming techniques. Most yield increases are in the range 15 to 30%. Average yields and yield increases are reported in Table 2. The dips in the corn and hay yield plots are very similar from one basin to the other, and often occur in the same years. Similar dips occur in soybean and wheat yields, but they are less apparent in Fig. 6 because of the scale of the plot and the range of the data. In part, these dips reflect the influence of weather patterns, mostly rainfall. In particular, 1988, the year with the most conspicuous dip in yields, was a year of very low rainfall, especially in the spring (April–June). The years 1991 and 1993 were also low-yield years and years of below-average rainfall. Yields for 1983 and 1985 show that other factors are also important: rainfall for these years was substantially lower than that for 1984 and 1986, but yields in 1983 were low while those in 1985 were intermediate between those for 1984 and 1986.

Nutrients
The science of nutrient management has advanced greatly during the study period. An evolution in perspective from fertilizer applications designed to build fertility levels to those aimed at maintenance, proper credits for nutrients applied in manures, precision application of fertilizers, and yield monitoring are all aspects of nutrient management that have matured substantially and come into widespread application during the study period. In addition, heightened awareness of environmental issues has strengthened incentives to use nutrients efficiently. These developments have undoubtedly been major causes of the trends in nutrient use detailed in the following paragraphs.

Sales of fertilizer increased in the early part of the study period, reached a peak about 1980, and have declined since then (Table 3). This pattern appears to reflect a change in attitude about fertilization. In the 1970s, the prevailing view about fertilizer was "more is better". In the early 1980s, this view began to change, as fertilizer prices increased and as soil tests revealed that many fields already contained as many nutrients as crops could use. In the Maumee watershed, sales of fertilizer phosphorus decreased 22% between 1971 and 1995, and 37% relative to their peak level in 1979 (Fig. 7). Fertilizer nitrogen sales have increased 23% relative to their level in 1971, but decreased 28% relative to their peak in 1981 (Fig. 8). In the Sandusky watershed, fertilizer phosphorus sales decreased 17% between 1971 and 1995, and 25% relative to their peak in 1979 (Fig. 7). Fertilizer nitrogen sales are anomalous: the data document a steady increase during the study period, amounting to 46% (Fig. 8). The reason for this continued and substantial increase is not apparent, though we note that the land area planted in corn has increased slightly in the Sandusky watershed while decreasing in the Maumee watershed. In addition, nitrogen from application of manure has decreased more sharply in the Sandusky watershed than in the Maumee (see below), perhaps requiring an increase in fertilizer nitrogen to compensate.

Row-crop agriculture has dominated the area during the period of study, and animal agriculture has been less important. Animal populations declined between 1975 and 1995, particularly those of cattle, dairy cows, and sheep. Consequently, production of animal manures and their associated nutrients also decreased. In the Maumee watershed, phosphorus associated with manure decreased by 17%, and nitrogen by 22%. In the Sandusky watershed, the decreases are larger: 34 and 37%, respectively.

Assuming that all manure produced and all fertilizer sold were applied to crops in the watershed, manure accounted for 24% of the phosphorus and 22% of the nitrogen applied in the Maumee basin, on average during the study period, and 20% of the phosphorus and 18% of the nitrogen applied in the Sandusky watershed. Phosphorus from fertilizer and manure decreased by 30% in the Maumee watershed and by 19% in the Sandusky over the period 1975–1995. Nitrogen from fertilizer and nutrients decreased by 8% in the Maumee watershed but increased by 10% in the Sandusky watershed.

In spite of reduced fertilizer use, it appears that soil phosphorus levels were higher at the end of the study period than at the beginning (Calhoun et al., 2002), reflecting a net import of nutrients into the watersheds throughout the study period (Baker and Richards, 2002).

Nutrients and Water Quality
In the Lake Erie watershed, the traditional focus of water quality management has been Lake Erie itself. For this reason, management efforts have been focused on reducing loadings to the lake of nutrients, especially phosphorus. The earliest efforts were directed at reducing loadings from point sources that discharged directly into Lake Erie, but reductions of nonpoint source loads were also needed to reach management goals (Baker and Richards, 2002). From this perspective, reducing loadings from agricultural sources within the study area has been essential, because agricultural land use dominates the study area (Richards et al., 2002) and the nonpoint source loads, and point sources upstream from the water quality monitoring stations have consistently been a small component of the annual loads of phosphorus (Richards and Baker, 1993; Baker and Richards, 2002).

More recently, increasing importance has been placed on improving the ecological condition of the rivers themselves. In this context, ambient concentrations are the most appropriate indicator of pollution status, and point sources (including faulty septic tanks) assume greater importance.

During the period of this study, however, efforts to rehabilitate Lake Erie were the most important environmental driving force for many of the changes in management practices that are documented in this paper (Forster and Rausch, 2002; Baker and Richards, 2002). The fact that many of the changes documented here are substantial and are in the direction that should lead to improved water quality suggests that water quality trend studies should show positive results as well. Water quality trends and their causes are the subject of several of the papers that follow.

	SUMMARY AND CONCLUSIONS

TOP ABSTRACT INTRODUCTION METHODS RESULTS AND DISCUSSION SUMMARY AND CONCLUSIONS REFERENCES

 
Many patterns of change were found in parameters reflecting agricultural land use patterns between 1975 and 1995. Most of the patterns were similar in both basins, both in direction and in magnitude. Farm size increased while the number of farms decreased; total farmland decreased only slightly. Conservation tillage is applied on nearly half the corn and soybean cropland. Enrollment in the Conservation Reserve Program amounts to five percent or less of the total farmland. Conservation plans have been developed and applied on most of the land identified as highly erodible.

Soybean and corn are the major crops in the watersheds, followed by wheat and hay. Cropland planted to soybean has increased, while that planted to wheat and hay has decreased. Cropland in corn decreased in the Maumee and increased slightly in the Sandusky. Per-hectare yields of all four crops have increased substantially.

Phosphorus applications from fertilizer and manure have decreased substantially in both basins from a high point around 1980, but soil fertility and nutrient mass balance studies reported elsewhere in this issue indicate a net increase in the phosphorus pool during the period of study. Nitrogen applications from fertilizer have increased during the study period, especially in the Sandusky watershed. Nitrogen associated with animal manure has decreased in both watersheds, due to declines in the number of animal units. Nitrogen associated with fertilizer and manure combined has decreased in the Maumee watershed but increased in the Sandusky. Agricultural nonpoint runoff remains the primary source of nutrient inputs to the Maumee and Sandusky rivers. Because of the dominance of agricultural land use in these basins, many of the changes documented in this paper must have played a significant role in observed improvements in water quality.

	ACKNOWLEDGMENTS

 
Data for CRP and conservation tillage trends were provided by the Conservation Tillage Information Center at Purdue University. Fertilizer use data were provided by the Ohio Department of Agriculture and the Indiana State Chemist. Point-source phosphorus loads were provided by the International Joint Commission, Windsor, and state agencies responsible for enforcing point-source permits. Other data were obtained from Ag Statistics divisions of the three state Departments of Agriculture. The help of all of these agencies in obtaining data not posted on web sites is particularly appreciated. This research was funded by USDA-CSREES through the Agricultural Systems for Environmental Quality project.

	REFERENCES

TOP ABSTRACT INTRODUCTION METHODS RESULTS AND DISCUSSION SUMMARY AND CONCLUSIONS REFERENCES

 

• Adams, J.R., T.J. Logan, T.H. Cahill, D.R. Urban, and S.M. Yaksich. 1982. A land resource information system (LRIS) for water quality management in the Lake Erie Basin. J. Soil Water Conserv. 37:45–50.
• Baker, D.B., and R.P. Richards. 2002. Phosphorus budgets and riverine phosphorus export in northwestern Ohio watersheds. J. Environ. Qual. 31:96–108 (this issue).[Abstract/Free Full Text]
• Calhoun, F.G., J.M. Bigham, and B.K. Slater. 2002. Relationships among plant available phosphorus, fertilizer sales, and water quality in northwestern Ohio. J. Environ. Qual. 31:38–46 (this issue).[Abstract/Free Full Text]
• Cleveland, W.S. 1979. Robust locally weighted regression and smoothing scatterplots. J. Am. Stat. Assoc. 74:829–836.[ISI]
• Eckert, D.J., and P.W. Levison. 1999. The changing face of agriculture in Ohio's Lake Erie basin. p. A28. In R.S. Schneider (ed.) Program and Abstracts, 42nd Conf. Int. Assoc. Great Lakes Res., Case Western Reserve Univ., Cleveland, OH. 24–28 May 1999. Int. Assoc. Great Lakes Res., Ann Arbor, MI.
• Forster, D.L., and J.N. Rausch. 2002. Evaluating agricultural non-point pollution programs in two Lake Erie tributaries. J. Environ. Qual. 31:24–31 (this issue).[Abstract/Free Full Text]
• Levison, P.W., and D.J. Eckert. 1998. Evolution of agriculture in the Lake Erie basin. p. 276. In 1998 Agronomy abstracts. ASA, Madison, WI.
• Moog, D.B., and P.J. Whiting. 2002a. Climatic and agricultural factors in nutrient exports from two watersheds in Ohio. J. Environ. Qual. 31:72–83 (this issue).[Abstract/Free Full Text]
• Moog, D.B., and P.J. Whiting. 2002b. Climatic and agricultural contributions to changing loads in two watersheds in Ohio. J. Environ. Qual. 31:83–89 (this issue).[Abstract/Free Full Text]
• Richards, R.P., and D.B. Baker. 1993. Trends in nutrient and sediment concentrations in Lake Erie tributaries, 1975–1990. J. Great Lakes Res. 19:200–211.
• Richards, R.P., and D.B. Baker. 1998. Twenty years of change: The Lake Erie Agricultural Systems for Environmental Quality (LEASEQ) project. p. 223–229. In Proc. Natl. Watershed Water Quality Symp., Washington, DC. 22–26 Sept. 1997. EPA/625/R-97/008. USEPA Office of Water, Washington, DC.
• Richards, R.P., and D.B. Baker. 2002. Trends in water quality in LEASEQ rivers and streams (northwestern Ohio), 1975–1995. J. Environ. Qual. 31:90–96 (this issue).[Abstract/Free Full Text]

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This Article Abstract Figures Only Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (8) Citing Articles via Google Scholar Google Scholar Articles by Richards, R. P. Articles by Eckert, D. J. Search for Related Content PubMed PubMed Citation Articles by Richards, R. P. Articles by Eckert, D. J. Agricola Articles by Richards, R. P. Articles by Eckert, D. J. Related Collections Tillage Surface Water Quality Best Management Practices Ecosystem Management Nutrient Management