Soil Compaction Research Summary

Soil compaction has become a major topic of discussion among scientists and crop producers in recent years. Even though some producers consider soil compaction to be a problem on their own farms, they feel resigned to the fact that there is little they can do to control it. Some recent solutions have been offered based on research efforts with soil compaction. There is significant interest in developing crop production systems with controlled traffic to help control the problem of soil compaction. There have also been new machine developments to address the problem of soil compaction, particularly with rubber tracked equipment and lower pressure tires

Residue Removal When Planting No-Till Corn

Plant residues from the previous crop are very effective in reducing soil erosion. However, if not properly managed, surface plant residues increase the risk of poor stand establishment for com (Zea mays. L.) and reduce yield potential of com when grown, especially following com, with conservation tillage production systems. A series of field studies evaluated residue management when planting com in no-tillage systems. Com planted by use of planters with residue clearing attachments emerges more rapidly than com planted with use of rolling coulter attachments. Row cleaners not only reduce plant residue above the seed row, but also result in less residue being placed into the seed zone. Removing residue from a 3- to 6-in band over the seed row allows rapid seedling emergence and good crop yields, while maintaining adequate residue cover for erosion control

Tillage Index Based on Created Soil Conditions

The ambiguity of current tillage nomenclature has led to much confusion. This report explains a uniform, comprehensive tillage index that was developed to avoid that ambiguity. It is based on row topography, residue cover, roughness, and tillage depth that result from passage of the tillage tool rather than on the tillage tool used. Examples of the use of this tillage index are presented. This index, because of its percentage crop residue cover and potential surface water storage components, will be useful when the Universal Soil Loss Equation is to be used for estimating erosion potential on a given field

Comparison of the Goryachkin Theory to Soil Flow on a Sweep

The Goryachkin trihedral wedge theories describe soil flow over a surface resembling the wing of a sweep. The current study tested the Goryachkin crushing and lifting theories’ prediction of soil flow across a sweep by comparing with measurements from observed soil flow. Treatments included sweeps with three different rake angles (13.5, 16, and 44°) operated at three speeds (5, 7, and 9 km/h) and at two depths (50 and 100 mm). Flow direction was determined from scratch marks on the sweep surface

Effective high-speed, high-residue rowcrop cultivation

Banding of herbicides linked with mechanical cultivation has been touted as a way to decrease dependence on chemical inputs in farming. Tests on a farm near Boone, Iowa, were used to determine the effects of cultivator design and speed when combined with the banding of chemicals to control weeds. Three cultivator styles, two speeds, and two herbicide bands (19 cm. and 38 cm.) were tested. Results showed that faster cultivation speeds did not harm weed control or crop yields. There was no difference between yield in a broadcast treatment and that of a cultivator treatment in conjunction with a wide band of herbicide when disc hillers were also used

Cultivator Design for Interrow Weed Control in No-till Corn

More than 95% of Iowa row crop acres are treated with herbicides. Such extensive use is an environmental concern. Banding of herbicides over the crop row, along with mechanical cultivation to control interrow weeds, has been proposed as a way to reduce herbicide use. Though cultivation is used on 74% of Iowa corn (Zea mays L.) land, herbicides are applied in a band on only 17% of the corn acres. This indicates that cultivation is not relied upon for interrow weed control. The risk that weather conditions will hinder completion of mechanical cultivation seems to discourage the use of herbicide banding. Higher speed cultivation could improve the odds of timely completion of needed cultivation. An experiment was conducted on a Clarion loam soil near Boone, Iowa in 1993 through 1996 to determine the effect of cultivator design and speed, when combined with the banding of chemicals, to control weeds. Three cultivator styles, two bands [19 cm (7.5 in.) and 38 cm (15 in.)], and two speeds were tested. A single cultivation management strategy was used. Data were taken in a no-till continuous corn rotation on 76-cm (30-in.) row spacings.Faster speed did not impede weed control or yield. In two years, the corn yield was greater and weed cover was reduced in plots cultivated at 11.2 km/h (7.0 mph) than in plots cultivated at 6.4 km/h (4.0 mph). Weed populations were greater in the 19-cm (7.5-in.) band than in the 38-cm (15-in.) band three of four years. In three of four years, leaf heights and yields were also significantly less for herbicide applied in a 19-cm (7.5-in.) band than in a 38-cm (15-in.) band. There was no difference between yield in a broadcast treatment and treatments which used a wide band of herbicide and a cultivator with disc hillers. In two years, the sweep and smith fin (a vee-shaped flat sweep with low rake angle) cultivator treatments resulted in less weed cover than the point-and-share treatment. In one year, the sweep and smith fin cultivator treatments had greater yield than the point-and-share treatment. Groundcover among cultivators showed few differences

Methods for measuring soil velocities caused by a sweep

A field experiment was conducted to measure surface soil velocity and to determine the relation between soil aggregate velocities at the tool surface and at the soil surface. A technique incorporating use of both a video camcorder and wood blocks was developed to measure surface soil velocity. Soil velocity direction at the tool surface was measured from scratch marks on the tool. Velocity measurements were made for three sweeps with different rake angles operated at three speeds and two depths. Surface soil moved in either of two modes: V-flow (upward and laterally in the shape of one leg of the letter V) or snowplow (initially moving upward and subsequently being buried in a wave of soil). Surface soil velocities were uncorrelated with velocities on the tool surface, indicating that soil flow paths over the sweep were not parallel. The ratio of vertical to lateral soil flow at the tool surface increased with larger rake angle and was greater than the ratio at the soil surface. At the soil surface, vertical velocity was greater near the nose than near the wing tip and velocity parallel to the travel direction increased with increased speed and rake angle