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Fluid Journal : Fluid Journal 1993-1995
1 Fluid Journal Late Spring 1993 Table 1. Precipitation during growing season, Arlington, WS. Year April May June July Aug Sept Oct ------------inches------------ 1991 4.52 1.91 2.63 3.75 1.78 4.37 6.75 1992 3.96 1.22 1.19 5.80 1.91 7.46 1.26 Table 2. Soil bulk density measured June 19, 1991 and October 13, 1992 at Arlington, WS. Soil Bulk Density ---- ----g/cc-- - ----- Depth (in.) Compaction (tons) 1991 1992 0-6 <5 1.19 (0.10) 1.30 (0.05) 14 1.36 (0.06) 1.41 (0.03) 6-12 <5 1.31 (0.06) 1.33 (0.04) 14 1.59 (0.05) 1.50 (0.13) 12-18 <5 1.19 (0.09) 1.35 (0.01) 14 1.45 (0.08) 1.44 (0.08) 18-24 <5 1.40 (0.07) 1.34 (0.03) 14 1.40 (0.07) 1.34 (0.03) Numbers in parentheses are standard deviations. n = 8 Summary: A relationship between wheel-traffic induced soil compaction and K fertility of corn has been demonstrated, but little is known about compaction problems in forages. The results of this study demonstrate the deleterious effect of soil compaction on the growth and yield of alfalfa. Wheel traffic compaction with a 14-ton vehicle produced detectable increases in soil bulk density and penetration well below the depth of tillage. Compaction signifiantly decreased the yield and K concentration of alfalfa tissue. Because of dry weather, these differences were not observed in the second cut, which may have actually favored growth on the compacted soil A favorable response to K fertilization, as measured by soil test K, was found. Even though a significant response to annual K fertilization was not observed in 1992, the trend of yield response and the effect on soil test demonstrated that rate was more important than placement. An interaction between soil test K and compaction was observed, suggesting that alfalfa is more responsive to K fertility on compacted soils.Plots were established in April of 1991 on a Piano silt loam near Arlington, Wisconsin. Treatments were arranged in a split-split plot design containing four replications. Compaction was established as the main plot treatment as either none or a double wheel- tracking over the entire plot with a 14- ton payloader. Soil moisture at compaction ranged from 22 to 25 percent by weight to a depth of two feet. Following compaction, plot area Drs. Richard P. Wolkowski and Larry G. Bundy Compaction Reduces Alfalfa Yield Two-year study shows effects of wheel compaction on yield and nutrient uptake. was disked twice to prepare a seedbed, treated with Eptam and seeded with alfalfa (Garst 636). Soil test K was established as the subplot treatment at anticipated levels of the indigenous (90 ppm), 150 ppm and 225 ppm. Sub- subplot treatments were none, 1 50 or 300 lbs/A K2O broadcast, or 75, 150 or 300 lbs/A K2O handed on 15-inch centers. All sub-subplot treatments were applied with liquid 0-0-62. Favorable growing conditions were experienced at Arlington both years. The season was warmer than usual in 1991 and cooler than usual in 1992. Rains were timely except for dry periods in August of 1991 and June of 1992. Dryness affected the growth of the second hay crop in each year. Precipitation is shown in Table 1. Yield reduction substantial Figure 1 shows the effect of compaction on yield. Note how compaction decreased yield substantially at all cuttings except the second cut in 1991 when it was dry. Other research has suggested that compaction can increase yield in dry
Fluid Journal 1996-1998