Sny Magill Watershed Project

USDA Water Quality Improvement Project

Sny Magill Watershed Farm Practices Survey

Sny Magill Creek is a high quality coldwater stream located in northeastern Clayton County Iowa, that is managed for "put and take" trout fishing. Landuse in the 22,780 acre watershed is primarily agricultural, with about 42% of the acres and crops and 37% in pasture.  Much of the remainder is woodland. The Sny Magill Watershed Project, funded through the USDA Hydrologic Unit Area Program, and the Iowa Water Protection Fund, provides technical assistance, information and education, and cost-share assistance to producers in order to improve water quality through voluntary changes in farm management practices. In late summer 1994, the Sny Magill Creek Watershed Project staff conducted a survey of land operators within the project area to update information on current farming practices. This fact sheet summarizes survey results and compares them to the results of the pre-project survey completed in 1991. Surveys are conducted periodically to assess the impact of the project.

A total of 45 farmers were contacted for this survey, which was prepared and reviewed by project and interagency staffs. Twenty-seven (60 percent) farm operators in the area responded. Survey findings assist in systematically documenting the adoption of practices that protect the environment and improve farm profitability.

Nitrogen management

The survey contained several questions about fertilizer rates and practices. Farmers were asked how their nitrogen (N) management has changed in the last three years. Nineteen operators responded they decreased their nitrogen rates. Eight respondents did not indicate a change in N applications rates, and none reported increasing N rates. Farmers were also asked about typical rates of purchased N applied to corn in various rotations in 1993.

Among 20 respondents with corn following corn in rotation with oats and hay, an average of 138 pounds of N per acre was applied. Of 20 respondents with corn following alfalfa, an average of 70 pounds per acre was applied. Second-year corn after alfalfa received an average rate of 120 pounds of N per acre, among the 19 respondents with this rotation. Of 16 respondents with continuous corn, an average of 138 pounds per acre was applied.

Survey results showed that nitrogen rates on corn following corn increased in the past two years, while rates on corn after alfalfa decreased. Nitrogen rates on second year corn after alfalfa remained the same (table 1). Results indicate minimal change from 1991 to 1993.

Table 1. Average N Fertilizer Rate Per Acre on Corn

Manure Management

Ninety-six percent of operators surveyed have both livestock and crops. On average, manure is distributed to 74 acres per farm. Management of manure for crop nutrients was examined in the survey. Twenty of 25 respondents rotate manure applications among different fields, and 18 of 24 adjust fertilizer rates to reflect manure contribution. Six of 26 operators responding test their manure for a more accurate value of its nutrient availability.

Pesticide Management

Ninety-eight percent of 1993 corn acres were treated with a herbicide. This is consistent with 1991, in which 99 percent of all corn acres were treated.
In the past three years nine out of 25 respondents reported reducing herbicide rates, and 15 out of 24 reported reduced insecticide rates. Although the data suggest farmers are refining pesticide practices, dependence upon herbicides for weed control remains.

For corn following corn rotations, 22 of 26 respondents use some form of conservation tillage. Seven of 22 use this same tillage for their corn following sod rotation. Conventional tillage (less than 30 percent residue; predominately moldboard plow) is used by three respondents on corn following corn rotations and by 14 on corn following sod.

Characteristics of respondents to the 1993 survey are unchanged from 1991, and within expected sampling error. Average farm size is 349 acres, with farms ranging in size from 25 to 805 acres. In 1991 the average size was 377 acres. Total corn acres inventoried in the 1993 survey was 4,440, representing 47 percent of the cropland. This is a 7 percent increase from 1991, when corn acres represented 40 percent of the cropland inventoried. Approximately 80 percent of corn acres surveyed are in a corn following corn rotation, with 14 percent in a corn following sod rotation. These rotations are consistent with those found in 1991 (Table 2).

Table 2. Crop Land Use

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Nolan R. Hartwig, interim director, Cooperative Extension Service, Iowa State University of Science and Technology, Ames, lowa.