WW-06187     1993  

Performance of Shrub Species as Field Windbreaks Under Center-Pivot Irrigation

HERMAN ROSHOLT RESEARCH FARM

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Figure 1. Identifying sign on Herman Rosholt Research Farm. Figure 2. Single-tower center-pivot irrigation system on Herman Rosholt Research Farm.

The Herman Rosholt Research Farm (Figure 1) is in the Bonanza Valley of west central Minnesota. It is located on Highway 28 at the southwest edge of Westport, Minnesota, about 14 miles northeast of Glenwood, Minnesota. Herman Rosholt, a retired farmer, donated this 40-acre tract of land to the Pope County Soil and Water Conservation District for experimental purposes. Thirty acres of the Herman Rosholt Research Farm is tillable. Clinton Welte, Brooten, Minnesota, donated the single tower center-pivot irrigation system (Figure 2). The irrigation system has an effective coverage of about 6.25 acres.

Pope County’s Soil and Water Conservation District Board furnished the farming equipment used on the Herman Rosholt Research Farm. A local farmer operated the equipment and performed weed control in the shrub plots.

Planting Site

The one-acre rectangular planting site on the Herman Rosholt Research Farm is located in the center of the south edge of the effective irrigation coverage. The soil (Esterville) is a well drained loamy sand with a moderately rapid permeability in the upper horizons and rapid permeability in the lower horizons.

The upper 18 inches of soil horizons at the test site are sandy loam and the lower 18–23 inches are loamy coarse sand. Gravelly coarse sand exists below 23 inches. The horizons are mostly neutral to medium acid. The slope is low, between zero percent and 2 percent. Native vegetation was tall grass prairie.

This soil is representative of 250,000 acres in the area now under irrigation. The site was in grass, primarily quackgrass (Agropyron repens [L.] Beauv.), before planting preparation. The southeast corner of the site is rocky and encompasses six test plots.

Plot Layout

Plot layout was a randomized, complete block design with 24-foot row plots replicated four times to accommodate 18 shrub species (Table 1). This provided a total of 72 plots. There were 15 rows and the spacing between rows was 20 feet (Figure 3). Most rows had five plots. Row number 1 on the west end and rows number 14 and 15 on the east end each had four plots.

The within-row spacings of the original 1979 planting were 4, 6, and 8 feet. Each plant’s spacing depended on crown characteristics of the species. Subsequent replantings were spaced at 6 feet. Agronomic crops were to be planted between the rows.

Agronomic Crops

Figure 4. Adzuki beans in 20-foot bays between shrub rows in 1979, the first year of the study. Sign lists the order of species in the 24-foot-row plots. Figure 5. Wheat and barley in 20-foot bays in 1980, the second year of the study. Zabels honeysuckle seen in the foreground. The photo was taken August 5, 1980.

The original purpose for growing agronomic crops between the shrub rows was to determine the effect of crop fertilizer and chemical treatments on the shrub species. In 1979 (Figure 4), Adzuki beans (Vigna angularis [Willd.] Ohwi & Ohashi) were grown between the shrub rows in the bays. In 1980 (Figure 5), wheat (Tricticum aestivum L.) and barley (Hordeum vulgare L.) were grown. Budget restrictions prevented the planting of crops from 1981 through 1986. Soybeans (Glycine max [L.] Merrill) were planted in 1987. Corn (Zea mays L.) was planted in both 1988 and 1989.

Site Preparation and
Weed Control

The planting site was plowed and disked in the fall of 1978. Unfortunately, a failure to consider weed control and treat with Roundup® (glyphosate) before the plowing and disking resulted in severe quackgrass competition for several years. Weed control following planting consisted of applications of Princep® (simazine) (granular or spray) in 1979 through 1981, Ronstar® (oxadiazon) in 1982 through 1984, Princep® in 1985 and 1986, and Casoron® (dichlobenil) in 1987 through 1989. Some Roundup® and rototilling was used every year.

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