Progress 12/01/08 to 09/30/11
Outputs
OUTPUTS: Pasturing dairy cows has environmental and economic benefits compared to feedlot production. In rotational grazing, cows are rotated around small paddocks spending only short periods in each paddock. This gives forage more time to regenerate after the cows pass through. Yet concentrating large numbers of animals in a small paddock even for a short time will result in compaction, which reduces amount and quality of forage. The purpose of this study was to investigate the effect of two promising compaction mitigation techniques on soil properties. Keyline plowing is a subsurface tillage technique which is thought to cut through compacted soil layers and provide additional drainage thus both mitigating existing compaction and preventing further compaction. In dryland farming it has been reported that this method can build organic matter and sequester C. In temperate climates however it is likely that the additional drainage provided by this method is going to increase decomposition and thus the organic matter content. The other techniques uses forage radishes that drive tap roots deep into the soil. This method has been used successfully to mitigate compaction in row crops in the Mid-Atlantic States. Both methods promise to affect soil strength, soil organic matter and macropore distribution. After its third year the study data does not show significant differences among treatments and controls. At one farm earthworm activity was greater in the keyline plowed pasture than in the untreated pasture. In particular earthworms that live among the pasture roots increased (endogeic worms). Likewise the number of earthworms in a pasture treated with radishes showed increased earthworm densities around the roots of the radishes. Earthworms can be taken as indicators of pasture soil health. Data was presented at the Fairlee Annual Vermont Grazer Conference in January 2010. This audience comprises graziers from Vermont, New England and as far afield as Pennsylvania. The study will continue under a new Hatch grant. Specifically we will address the effect of macropores on infiltration rates and the transmission of water and nutrients through the soil. Radish treatments are spatially very heterogeneous and we will have to apply improved sampling schemes next year to further probe the effects of radish growth in more successful radish treatments. Collaborating commented that keyline plowing left scars that required additional soil management and that they would rather work with radishes. That part of the study will be discontinued. PARTICIPANTS: The project provided training for two graduate students: Bridgett Jameson (MS student) who obtained two SARE grants that further supported this project; and Peter Austin (MS student) Rachel Gilker and Jennifer Colby, grazing specialists at the Center for Sustainable Agriculture provided much positive guidance and many insights. TARGET AUDIENCES: Dairy farmers provided land and labor for this work. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The study is measuring organic matter, soil strength, pH etc. for plots with no treatment, with radish plantings and with keyline tillage. The two treatments are thought to counteract compaction. The hypothesis is that the mitigation techniques result in improved soil quality. Results indicate that there are indeed changes in the soil quality as indicated by changes in the number of earthworms. However, directly measured soil properties such organic matter and active carbon showed no statistically significant effects over three years. Keyline plowing was specifically designed to redistribute water in arid rangelands from landscape areas where storm water collects to drier. This has led to claims that rangeland productivity can be increased and that more C can be sequestered as soil organic matter. However, in Vermont the hydrologic condition of fields are the opposite. Often pastures are wet and organic matter may have accumulated already. We are finding that in wet pastures that were keyline plowed soil moisture decreased in comparison to the control plots where no treatment was applied. Similarly inconclusive are the results in the radish treatments. We did see some improvements in compaction at some farms but the results may be affected by season. In three out of four farms, compaction was reduced in the keyline treatments. At one farm compaction stayed the same. One of the difficulties is that the soils at the collaborating farms were of different initial quality so that differences between the early and the present sampling depend on the farm. Some farms had outstanding soils already and changes in quality would probably be too small to detect. Benefits of this research include mitigation and prevention of compaction, improved pasture productivity and potentially the sequestration of C. Primary beneficiaries are dairy farmers who use grazing as an alternative to feed lot production. These stakeholders who participated in the NE Pasture Consortium Meeting in Albany this year and at the Fairlee Grazing and Livestock Conference showed great interest in managing soil health with these new methods, in particular the tillage radishes.
Publications
- UVM Center for Sustainable Agriculture. 2012. Pasture Improvement Tools: Tillage Radishes and Keyline Plowing. Factsheet.
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Progress 10/01/10 to 09/30/11
Outputs
OUTPUTS: Pasturing dairy cows has environmental and economic benefits compared to feedlot production. In rotational grazing cows are rotated around small paddocks spending only short periods in each paddock. This gives the forage more time to regenerate after the cows pass through. On the downside, large number of animals stocked into a small area may cause compaction and thus reduce production and quality of forage. The purpose of this study is to investigate the effect of two promising compaction mitigation techniques on soil properties. Keyline plowing is a subsurface tillage technique which is thought to cut through compacted soil layers and provide additional drainage thus both mitigating existing compaction and preventing further compaction. The other techniques uses forage radishes that drive tap roots deep into the soil. We are particularly interested in the development of soil strength, soil organic matter and macropore distribution. In its second year the study will continue to gather data. During the reporting period, one more generation of radish was grown at two collaborating farms and two more passes of keyline plowing was accomplished at four collaborating farms. Each practice was sampled twice during this period. Fertility data, soil strength, and organic matter data was collected during the last year and results reported to the farmers. Data was presented at the Fairlee Annual Vermont Grazer Conference in January 2010. This event attracts graziers from Vermont, New England and as far afield as Pennsylvania. In addition, results from the study were presented at the Annual Meeting of the Soil Science Society of America. Next year we will continue working with 4 producers who have been implementing these management techniques for the past two years. Radish treatments are spatially very heterogeneous and we will have to apply improved sampling schemes next year to further probe the effects of radish growth in more successful radish treatments We will also some questions regarding how macropore flow potentially created by both treatments may affect infiltration. PARTICIPANTS: Josef Gorres is the principal investigator on this project. His expertise is in soil physics and soil ecology. He works closely with Dr. Rachel Gilker of the Center of Sustainable Agriculture of the University of Vermont Cooperative Extension. Dr. Gilker is a grazing specialist. She is a principle investigator on a closely related CIG grant. Bridgett Jamison is a graduate student in Dr. Gorres laboratory and has been conducting field and lab tests for this study. TARGET AUDIENCES: The target audience are mainly dairy farmers. Participating farmers receive information about their soils. In addition we participate in the Vermont Grazing Conference that reaches many stakeholders and collaborate with the UVM Pasture Network. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
New management practices may take a while to show results. The study is measuring organic matter, soil strength, pH etc for plots with no treatment, with radish plantings and with keyline tillage. The latter two treatments are thought to counteract compaction. The hypothesis is that the mitigation techniques result in improved soil quality. Results indicate that there are indeed changes in the soil quality. However, because we have only sampled twice so far, the observed changes may be due to seasonal variations. The study is now in its second year and a third sampling has been conducted with a fourth planned in the Spring 2012. We expect that some outcomes are becoming clearer with the analysis of additional samples when seasonal effects can be separate from treatment effects. Keyline plowing was specifically designed to redistribute water in arid rangelands from landscape areas where storm water collects to drier. This has led to claims that rangeland productivity can be increased and that more C can be sequesterd as soil organic matter. However, in Vermont the hydrologic condition of fields are the opposite. Often pastures are wet and organic matter may have accumulated already. We are finding that in wet pastures that were keyline plowed soil moisture decreased in particular near where the shanks have cut into the soil. Yet, we have not yet observed any significant changes in organic matter or in easily decomposed carbon. Similarly inconclusive are the results in the radish treatments. We did see some improvements in compaction at some farms but the results may be affected by season. In three out of four farms, compaction was reduced in the keyline treatments. At one farm compaction stayed the same. One of the difficulties is that the soils at the collaborating farms are of different quality so that differences between the early and the present sampling depend on the farm. Benefits of this research include mitigation and prevention of compaction, improved pasture productivity and potentially the sequestration of C. Primary beneficiaries are dairy farmers who use grazing as an alternative to feed lot production. These stakeholders are interested in managing compaction issues and have expressed an interest in these two novel management techniques which may also have C sequestration benefits.
Publications
- No publications reported this period
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Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: The purpose of this project is to see how earthworms modify the the amount of organic matter and the structure of soil aggregates (clumps of soils that combine many soil particles in a larger coherent unit) as habitat of other beneficial soil organisms. A greenhouse experiment was conducted in which three earthworm treatments and one control treatment were analyzed for leached nutrients. Analyses of aggregates from these treatments are still to be carried out pending the installation of an instrument that measures the pore structure in individual soil aggregates. Important questions that remain is how organic matter is distributed among aggregates of different sizes and whether that organic matter makes pore structure more inhabitable for soil organisms involved in nutrient cycling. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
In a lab experiment, the common night crawler (Lumbricus terrestris) significantly reduces the amount of calcium leached (an element which is an essential element of lime often added to improve soil fertility). The amount of calcium leached from a treatment with a more aggressively invading worm, Amynthas agrestis, on the other hand maintains calcium losses at the level of the control. Lumbricus species, including L terrestris, do not have lungs and carbon dioxide needs to be disposed of in a different form of respiration. Lumbricus species have the ability to fix calcium using a calciferous gland that combines calcium and carbon dioxide to make calcite, a calcium carbonate mineral that is not easily dissolved and leached. This sequesters carbon dioxide from the atmosphere into the soil. How this process changes organic matter in the soil is unknown. Further tests are to be conducted next year. These tests will include measurements of carbon dioxide and methane gases from soils with and without L. terrestris. The outcome of these new experiments may impact the discussion on carbon sequestration with respect to climate change as well as agronomists concerned with calcium availability in soils.
Publications
- No publications reported this period
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Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: The purpose of this project is to investigate the impact of earthworms on organic matter, aggregation and soil chemistry in production sugar maple stands. Two sites were investigated to date: A sugar maple stand at a midsized producer of maple syrup in Cabot, Vermont, and at the Proctor Maple Research Center (PRMC) of the University of Vermont. At the PRMC, we established plots to investigate how the forest nutrient availability is related to the abundance of earthworms and soil properties. At the Cabot site, the availability of nutrients was investigated in soils with high abundance of earthworms (soil structure greatly disturbed by burrowing of worms, casts visible at surface) and low abundance of earthworms (duff layer intact, and no casts visible at surface). The presence of earthworm increased the availability of calcium ions in soils at the expense of other cations. In soils with earthworms, 5 times more calcium was available than in soils without worms. Potassium on the other hand, was 4 times less available in soils with earthworms than in soils without them. The presence of earthworms skewed inorganic nitrogen availability towards nitrate, the more mobile nitrogen species in soils. The ratios were 17 to 1 (nitrate to ammonium) for soils with earthworms and 6:1 (nitrate to ammonia) for soils without earthworms. Soils that have high abundance of earthworms may lose more nitrogen since they favor the species of nitrogen that is more likely to leach or be part of runoff as through flow along slopes. The changes in nutrient availability with earthworm abundance may engender changes in the ecology of maples forests as well as soil structure. Further investigations will analyze soils for organic matter distribution in water stable aggregates, the potential effect of nutrient availability on the maple sap quantities and quality, and over the longer term the effect of these changes on canopy species. The project will be continued under a new Hatch project and a submission to the USDA-AFRI is planned. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Earthworms strongly affect the availability of nutrients and the speciation of nitrogen ions under sugar maple. This study is still in its early stages. It is hoped that the relationship between chemical and physical structure changes and the quality of maple sap can be probed in the near term, and that changes in soil chemistry can help estimate the output and fate of nutrients from earthworm invaded sugar maple stands. Changes in soil chemistry have been hypothesized by others involved in acid precipitation research to affect forest quality. IN the long run this project may provide data to investigate the fate of hardwood forests in the Northeast.The potential beneficiaries of the data collected will be forest managers, maple syrup producers and environmental scientists. Among the benefits that can be generated with this study and its follow up are estimates of nitrate losses from soils and potential predictive estimates of acidification of soils as a function of earthworm action. Nitrate losses are associated with water quality issues and with the loss of cations from the soil. The latter may affect ecosystem function and thus the fate of these forests.Although the study of earthworm related effects on ecosystems are becoming more important, there still is only a small body of knowledge on invasive earthworms in northern hardwood forests. More knowledge on these effects may eventually inform conservation efforts by stakeholders.
Publications
- No publications reported this period
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