Aeration Tillage Effects on Hay Yield and Soil Health in Clay Soils

Aeration Tillage Effects on Hay Yield and Soil Health in Clay Soils

Summary

Vergennes and Covington clay soils used for grass hay production in the Champlain Valley of Vermont are subject to soil compaction over time as equipment travels over the crop for multiple passes of equipment for maintenance and harvest operations. Three field sites were selected in Bridport and Addison, VT, to impose repeated aeration tillage treatments using a Gen-Till aerator, a single-axle Aerway, or a double-axle Aerway aerator tillage implement. Crop yields were measured during 2014 and 2015 and forage samples submitted to Dairy One Forage Testing Laboratory for complete NIR forage analysis. Soil samples were submitted to UVM Agricultural & Environmental Testing Lab for complete basic soil test analysis, and to Cornell Soil Health Test Lab for evaluation of physical, biological and chemical properties to evaluate overall soil health quality and constraints.

Grass hay yields at the Bridport site were not significantly affected in 2014 following aerator tillage, but then resulted in 2015 first cut hay dry matter yield increases of 28% for single-axle and 11% for double-axle Aerway tillage treatments. Grass hay yield at the Addison site increased 38% by using aeration tillage in 2014 and was not significantly different in 2015. Soil compaction at the Addison site was reduced by 4% and water holding capacity increased by 7% in the aerated plots compared to non-aerated plots.

Initial soil health assessments indicate that these clay soil sites have high priority constraints of surface hardness (compaction) and suboptimal functioning of available water capacity. Increasing late summer soil moisture holding capacity of clay soils is one goal that local farmers are seeking as Addison County experiences a late season drought nearly every summer. The combined improvements to soil condition by decreasing soil compaction and increasing water holding capacity by repeated aeration tillage provides improved field conditions that allow for increased potential crop yields.

Objectives/Performance Targets

Three field sites were established on Vergennes clay soil in Bridport and Addison, VT to measure aeration tillage effects on grass hay yield and soil health quality in the typical clay soils that farmers manage in the Champlain Valley.

The Bridport site received one year of aeration treatments (3) and yield data collection continued through first crop harvest in the second year. The farmer opted out of the trial after that time.

The Addison site aeration tillage was repeated for two years and yield data corresponds with each individual harvest during 2014 and 2015. Soil health and basic soil test sampling was completed at the end of the growing season in 2015 (results are pending from the lab) for comparison with previous year results.

The farmer has expanded use of aeration tillage to include entire farm.

Accomplishments/Milestones

Bridport Site

The one field site in Bridport did not receive any aeration tillage treatments in 2015. The single-axle and double-axle aerator treatments were done three times in 2014 after a spring application of 2 ton/ac composted chicken manure. In 2015, first cut hay was sampled using quadrat sampling to determine dry matter yields and forage quality measures. The first cut harvest yields were measured to determine any carryover effect from the treatments imposed in 2014.

Addison Site

The two field sites in Addison at the Gould Farm received three aeration treatments in 2015 after each of the first, second and third hay harvests in June, August and November. The early spring aeration was not done this year because of concerns that the early spring aeration in April of 2014 decreased yields due to slot sidewall compaction in wet soils. The late fall aeration scheduling replaces the early pre-season spring aeration treatment that was originally planned for each year.

Fertilizer was applied in early spring and after each of the two or three hay harvests. Each field received 25 lb/ac N on April 15 at early spring growth using a 30-5-10 analysis fertilizer broadcast applied at 85 lb/ac. After first hay harvest an additional 30 lb/ac N was applied to both fields using a combination of 30-5-10 (52 lb/ac) plus Urea 46-0-0 (52 lb/ac). One field (DG1) received a third application of fertilizer (30-5-10) at 52 lb/ac after a third harvest was taken. Total maximum annual nutrients applied was 84 lb/ac N, 10 lb/ac P2O5, and 20 lb/ac K2O, which was less than UVM soil test recommendations.

The farmer tracked field activities by recording fertilization, aeration tillage and hay harvest information on a field-scale basis. Aeration tillage in the fields was guided and recorded by using a AFS FM-750 GPS steering guidance display for agricultural equipment.

Crop yields were measured by two separate methods for each harvest. The farmer counted harvested dry bales of hay for each harvest, and Extension field staff collected multiple 1.5 square foot quadrat samples that were clipped from each treatment area, weighed and a composite sample sent to Dairy One Forage Testing Laboratory for a complete NIR forage analysis to determine forage characteristics for nutrient uptake

Soil samples were collected from each treatment block in November, 2015 and sent to Cornell Soil Health Test lab for analysis. Soil compaction in the treatment areas was measured using a manual soil penetrometer to record the maximum pressure (psi) required to penetrate the soil from 0 to 6 inch depth and 6 to 18 in. depth as part of the Cornell Soil Health Test field procedures. The soil moisture was measured at 4.7 in. depth using a Spectrum Technologies Field Scout TDR 300 soil moisture meter at the same time as soil compaction measurements were taken.

Impacts and Contributions/Outcomes

There was a slight 1% reduction in 2014 yields at the Bridport site comparing a single axle Aerway with the control treatment, and a 3% yield reduction using the double-axle Aerway tillage implement. The aeration tillage was more aggressive in disturbing soil at this site than at the other site using a different type of aerator. In 2015 the first cut hay crop was greater than the control by 28% in the single axle Aerway treatment area, and 11% in the double-axle Aerway treatment. No additional fertilizer was applied in 2015, so yield increase from aeration tillage was a reflection of carry-over effect from the previous year treatments on soil yield potential. The Bridport site was discontinued after this harvest because the farmer did not want to continue the aeration tillage with concerns about expense of tillage operation and damage to the grass sod.

Aeration tillage at the Addison site was done with a Gen-till aeration toolbar three times in 2015. Total aeration treatments have been implemented eight times from fall 2013 through fall 2015 (2013-1x, 2014-4x, 2015-3x). Dry matter (DM) hay yields in 2014 at the Addison site were increased 37% and 40% in fields DG1 and DG4 respectively by using aeration tillage. In 2015 there was only a 1% overall increase in the harvested yields between aerated and non-aerated plots. 2015 was very wet in June with over 8.5” of rain which compounded the low fertility regime used by the farmer leading to overall reduced yields. Increasing fertilization rates to meet UVM recommendations (150 lb/ac N) may have produced improved yield results.

At the end of the 2015 crop season, soil compaction in the four aerated field plots was reduced by 4% in the 0 to 6 inch depth range and by 3% in the 6 to 18 inch depth range. The soil moisture content (mc) in the aerated plots was 7% greater than in the non-aerated plots, 35% mc v 32% mc, indicating a greater capacity to infiltrate and hold plant available water. The combined improvements to soil condition of decreased soil compaction and increased water holding capacity should provide conditions that allow for greater yield potential. The increase in soil moisture holding capacity is one goal that local farmers are seeking as Addison County experiences a late season drought nearly every summer.

The farmer at the Addison site, Doug Gould, used the FM-750 GPS steering guidance unit that we provided to track aeration tillage activities in the field. As a result, he has purchased his own GPS guidance system to use while aerating or during fertilizer application to improve field efficiency of machinery operations. Doug feels this aeration of the soil is very beneficial and he has extended use of this repeated aeration tillage management to include all acreage on his farm.

Collaborators: