Progress 09/05/08 to 08/15/13
Outputs
Progress Report Objectives (from AD-416): The long-term research objective of this project is to develop and translate fundamental agroecological knowledge into recommendations and products to improve the economic position of organic farmers and to improve their ability to meet consumer demand for organic products. Objective 1 is to develop component technologies and management strategies that lead to improved productivity, enhanced soil and water conservation, and efficient nutrient cycling on organic farms. Objective 2 is to understand agroecological principles that drive the function of organic cropping systems and quantify ecosystem services. Approach (from AD-416): Approaches to developing component strategies include A) incorporating legumes into organic crop rotations to maximize nitrogen fixation, B) composting that provides a productive and safe amendment for organic agriculture, and C) optimal agronomic practices for managing nutrients and production on organic farms. Approaches to determining agroecological principles include investigating the following variables within the Beltsville long-term Farming Systems Project that compares two conventional and three organic rotations, A) crop performance, B) soil nitrogen dynamics in relation to nitrogen inputs, C) soil carbon sequestration and greenhouse gas flux, D) soil biological community structure in relation to soil quality and production performance, and E) soil erosion and nutrient loss potential. During the five year life of this project, researchers working at the long-term Farming Systems Project (FSP) found that increasing crop rotation length and complexity reduce production and other challenges in organic systems. Corn yield was 10 and 30% greater in a crop rotation that included a perennial forage crop compared to shorter rotations that included only annual crops. Increasing crop rotation length and complexity also reduced predicted soil erosion, soil nitrous oxide (N2O) emissions, economic risk, animal manure inputs and soil phosphorus loading. Additional progress in the past year is described below. Field experiments to evaluate OMRI-approved fertilizers in organic forage production are in their fourth year (sub-obj. 1.A). Test mixtures containing dairy manure solids, old hay and animal bedding, and vegetative food waste were composted using a mechanically aerated in- vessel composting system, and procedures for evaluating gaseous emissions were developed, tested, and installed (sub-obj. 1.B). The second year of field studies comparing survival of generic and non-pathogenic strains of Escherichia coli in organically and conventionally managed fields were conducted using various amendments (sub-obj. 1.B). We performed experiments to evaluate the impact of cover crop mixes (rye, hairy vetch) and manure sub-surface banding on soil N2O emissions (sub-obj. 1.C). The lead scientist collaborated with scientists from the University of Maryland to compare N2O emissions from organically-managed vegetable crops grown using four different cover crop management practices (sub-obj. 1.C). We monitored population and community dynamics and weed-crop competition for a fourth year in permanent weed-free and weedy check plots in organic and conventional systems in the FSP (sub-obj. 2.A). Manuscripts were initiated describing research that evaluated the influence of long-term soil management on weed-crop competition relationships (sub-obj. 2.A). We compiled 14 years of data to compare nutrient budgets (N, P, K, C) and evaluate nutrient management, and to compare carbon budgets and evaluate soil carbon sequestration and potential sequestration mechanisms among cropping systems at the FSP (sub- obj. 2.B, sub-obj. 2.C). We characterized soil carbon fractions collected from diverse FSP systems using near-infrared, mid-infrared and pyrolysis spectra as part of our effort to evaluate mechanisms of soil carbon sequestration (sub-obj. 2.C). A scientist from Brazil (EMBRAPA), in association with colleagues at the University of New Hampshire, compared output from the DNDC model with two years of soil N2O emissions data to evaluate model predictions among FSP cropping systems (sub-obj. 2. C). A visiting PhD student from Brazil and a high school intern measured soil N2O emissions following application of conventional and newly- designed slow-release nitrogen fertilizers (sub-obj. 2.C). A multi- location project was initiated by NP216 project scientists to determine indirect and legacy effects of glyphosate application on soil resident microbes associated with corn and soybean roots and implications for general plant health (sub-obj. 2.D). Significant Activities that Support Special Target Populations: Members of this project�s research team participated in planning, organizing, and conducting the 14th Annual Future Harvest-CASA Conference, �Farming for Profit and Stewardship,� Landsdowne, VA, January 18-19, 2013. This conference targeted small farms, and female and organic producers in the mid-Atlantic area. Minority and disadvantaged farmers in Virginia and North Carolina were the target groups for the 10th Annual Small Farm Family Conference held in Danville, VA on October 30-31, 2012. A project member was instrumental in organizing and planning this conference, and is serving in a similar capacity for the 11th annual �Small Farm Family Conference� to be held in Lynchburg, VA in 2013. Members of this project�s research team were instrumental in organizing the 21st Annual Meeting of the Maryland Organic Food and Farming Association on February 16, 2013 in Annapolis, MD and the 8th Annual Queen Anne�s County Organic Production Meeting, March 12, 2013 in Wye Mills, MD. Accomplishments 01 Reducing soil greenhouse gas emissions will require novel agricultural approaches. Agricultural soils are the dominant source of nitrous oxide (N2O), a greenhouse gas and catalyst of stratospheric ozone decline. U.S. emissions continue to increase despite substantial increases in crop and animal productivity and associated reductions in N2O emissions per unit of production. Reducing emissions of N2O requires novel approaches because of the complex, mostly biological, processes responsible for its production. ARS scientists from the Sustainable Agricultural Systems Laboratory, Beltsville, MD and other areas along with university and industry colleagues summarized trends and challenges of reducing N2O emissions for the National Climate Assessment (NCA), coordinated by the President�s Office of Science and Technology Policy. A modeling analysis in the NCA completed in cooperation with ARS scientists from Fort Collins, CO, showed that N2O emissions can be substantially reduced by decreasing consumption of animal protein in developed countries and intensifying agriculture in developing countries. These results are of interest to policymakers who rely on scientific data to make decisions. 02 Organic cropping systems provide ecosystems services that rival no-till cropping systems. Organic farming ecosystem services have not been compared to those of conventional no-tillage farming in the past. ARS scientists in the Sustainable Agricultural Systems Laboratory at Beltsville, MD, using data from the long-term Farming Systems Project, found that soil carbon storage and nitrogen fertility can be greater, while impact on climate change can be lower in organic systems using animal manures and cover crops compared to conventional no-tillage systems using conventional fertilizer and cover crops. Ecosystem services of organic systems are improved by expanding crop rotations to include greater crop diversity, using integrated nutrient management, and reducing tillage intensity and frequency. However, soil erosion and labor requirements are greater and crop yields, on average, are lower in organic than no-tillage systems. This research quantifies how organic farming practices can improve provision of ecosystem services and also how organic farming can be improved, and is of interest to organic farmers, farmers considering transitioning to organic, and policymakers and others interested in augmenting ecosystem services provided by all farming systems. 03 Genetic control of hairy vetch flowering time decoded. In no-till organic cropping systems the onset of flowering indicates the earliest time a farmer can mechanically terminate cover crops without the use of herbicides or tillage. Developing earlier-flowering cover crops should increase adoption of these conservation cropping systems since the late planting dates necessitated by late flowering cover crops can be a disincentive to adoption. ARS scientists from the Sustainable Agricultural Systems Laboratory, Beltsville, MD identified genetic traits associated with significant variation in flowering time among accessions in the USDA hairy vetch germplasm collection. Five key flowering genes associated with initiation or inhibition of flowering were identified among the hairy vetch genotypes. These genes are regulated during transition from vegetative to flowering growth stages. Information on differences in the regulation of these genes could be used to rapidly identify hairy vetch varieties in future breeding programs with flowering times better synchronized with agronomic needs. This information is useful to crop breeders and other scientists interested in improving the value of hairy vetch as a cover crop. 04 Some types of biochar may increase N losses from soil. Biochar is a carbon rich byproduct from pyrolysis of plant biomass that can increase soil productivity and can be used for long-term storage of carbon in soils. Limited information is available on how biochar influences different nitrogen pools in the soil and nitrogen availability to crops. ARS scientists from the Sustainable Agricultural Systems Laboratory, Beltsville, MD in collaboration with University of Georgia cooperators found that biochar made from pecan shells, peanut hulls, and poultry litter increased losses of nitrogen from soils. Losses were the result of ammonium volatilization caused by biochar-induced increases in pH. Little evidence of increased inorganic nitrogen retention or mineralizable N fractions was observed when these biochars were added to soil. Responses varied among biochars, indicating the need for caution in use of biochar in agricultural soils. Biochar chemical and physical characterization could help aid in matching biochar to soil type as well as identifying appropriate land use. These results will be of interest to farmers, agricultural professionals and others considering using, or advising on the use of, biochar. 05 Managing soil biodiversity and ecosystem services. Ecosystem services are those provided by natural systems, such as providing clean drinking water, regulating climate, crop pollination, and recycling of decomposing materials. Many ecosystem services are carried out by soil organisms. The impact of the diversity of soil organisms on provision of ecosystem services has not been well summarized. ARS scientists from the Sustainable Agricultural Systems Laboratory, Beltsville, MD and a University of Maryland colleague synthesized the latest information regarding managing soil biodiversity and the impact on attendant ecosystem services in a book chapter. Agricultural management impacts on ecosystem services and soil biodiversity were often complex. Management responses may be subtle and vary with soil type, climate, ecosystem, type of organism and ecosystem service. Nonetheless, management that improves ecosystem services is also likely to improve soil biodiversity. This information will be of interest to the international agricultural research community that is increasingly recognizing the crucial roles ecosystem services play in intensive agricultural production systems. 06 Composting at high temperatures kills disease organisms of cacao. Cacao pod husks, which are typically left in the field after cacao beans are harvested, represent a major disposal problem for the cacao industry and can serve as a significant reservoir of disease inoculum. Composting and anaerobic digestion were investigated as potential disinfection technologies and as a means of producing an organic fertilizer for cacao farmers. In laboratory experiments ARS scientists from the Sustainable Agricultural Systems Laboratory, Beltsville, MD, found that disease organisms that survived when composted using standard techniques did not survive under thermophilic composting conditions, even for short periods. Fifteen hour exposure in a 35C mesophilic anaerobic digestor will disinfect cocoa pod husks of Phytophthora, thereby rendering the compost or digestate suitable for horticultural uses as an organic fertilizer. These results will be of interest to the cocoa industry. 07 Solarization and biofumigation reduce survival of harmful bacteria on spinach leaf residue incorporated into soil. Contamination of spinach and raw vegetables by E. coli and Salmonella has resulted in hundreds of cases of gastroenteritis, numerous cases of kidney failure, and even fatalities. The leafy greens industry has incurred millions of dollars of economic losses from reduced sales and from compensation settlements to victims of foodborne illnesses. Preventing contamination of fresh produce is an important crop protection strategy. Animal manure used as fertilizer or left by wildlife can contribute bacterial contaminants. High tunnel production provides some environmental protection for high value crop production, but cannot exclude all wildlife. This study showed that covering soil with a clear plastic film (solarization) and using biofumigation techniques (cabbage leaf incorporation into soil, 20 percent vinegar drench, or a commercially-available, organically- approved plant disease control soil drench) significantly reduced E. coli survival over a two week period. Non-treated soil and the white and black plastic reduced E. coli populations, but not as dramatically as the clear plastic film. These results are important because they show that soil solarization combined with natural product biofumigants provide an effective strategy to reduce E. coli contamination in high value produce cropping soils in a short time. These results will be of interest to organic and conventional leafy greens producers and the leafy greens processors and marketers.
Impacts
(N/A)
Publications
- Spargo, J.T., Cavigelli, M.A., Alley, M.M., Maul, J.E., Buyer, J.S., Sequeira, C.H., Follett, R.F. 2012. Changes in soil organic carbon and nitrogen fractions with duration of no-tillage management. Soil Science Society of America Journal. 76(5):1624-1633.
- Culman, S.W., Snapp, S.S., Freeman, M.A., Schipanski, M.E., Beniston, J., Lal, R., Drinkwater, L.E., Franzluebbers, A.J., Glover, J.D., Grandy, A.S., Lee, J., Six, J., Maul, J.E., Mirsky, S.B., Spargo, J.T., Wander, M.M. 2012. Permanganate oxidizable carbon reflects a processed soil fraction that is sensitive to management. Soil Science Society of America Journal. 76:494-504.
- Cavigelli, M.A., Maul, J.E., Szlavecz, K. 2012. Managing Soil Biodiversity and Ecosystem Services. In: Wall, D.H., Bardgett, R.D., Behan-Pelletier, V. , Herrick, J.E., Jones, T.H., Ritz, K., Six, J., Strong, D.R., van der Putten, W.H., editors. Soil Ecology & Ecosystem Services. London, England: Oxford University Press. p. 337-356.
- Cavigelli, M.A., Del Grosso, S.J., Liebig, M.A., Snyder, C.S., Fixen, P.E., Venterea, R.T., Leytem, A.B., McLain, J.E., Watts, D.B. 2013. US agricultural nitrous oxide emissions: context, status, and trends. Frontiers in Ecology and the Environment. 10:537-546.
- Venterea, R.T., Halvorson, A.D., Kitchen, N.R., Liebig, M.A., Cavigelli, M. A., Del Grosso, S.J., Motavalli, P.P., Nelson, K.A., Spokas, K.A., Singh, B.P., Stewart, C.E., Ranaivoson, A., Strock, J., Collins, H.P. 2012. Challenges and opportunities for mitigating nitrous oxide emissions from fertilized cropping systems. Frontiers in Ecology and the Environment. 10(10)562-570.
- Cavigelli, M.A., Mirsky, S.B., Teasdale, J.R., Spargo, J.T., Doran, J.W. 2013. Organic management systems to enhance ecosystem services. Renewable Agriculture and Food Systems. 28:145-159.
- Schomberg, H.H., Gaskin, J.W., Harris, K., Das, K.C., Novak, J.M., Busscher, W.J., Watts, D.W., Woodroof, R.H., Lima, I.M., Ahmedna, M., Rehrah, D., Xing, B. 2012. Influence of Biochar on Nitrogen Fractions in a Coastal Plain Soil. Journal of Environmental Quality. 41(4):1087-1095.
- Mothapo, N.V., Maul, J.E., Shi, W., Isleib, T., Grossman, J.M. 2013. Genetic diversity of resident soil rhizobia isolated from nodules of distinct hairy vetch genotypes. Applied Soil Ecology. 64:201-213.
- Skinner, E.M., Diaz-Perez, J., Phatak, S., Schomberg, H.H., Vencill, W. 2012. Allelopathic effects of sunnhemp (Crotalaria juncea L.) on germination of vegetables and weeds. Journal of Environmental Quality. 47(1):138-142.
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Progress 10/01/11 to 09/30/12
Outputs
Progress Report Objectives (from AD-416): The long-term research objective of this project is to develop and translate fundamental agroecological knowledge into recommendations and products to improve the economic position of organic farmers and to improve their ability to meet consumer demand for organic products. Objective 1 is to develop component technologies and management strategies that lead to improved productivity, enhanced soil and water conservation, and efficient nutrient cycling on organic farms. Objective 2 is to understand agroecological principles that drive the function of organic cropping systems and quantify ecosystem services. Approach (from AD-416): Approaches to developing component strategies include A) incorporating legumes into organic crop rotations to maximize nitrogen fixation, B) composting that provides a productive and safe amendment for organic agriculture, and C) optimal agronomic practices for managing nutrients and production on organic farms. Approaches to determining agroecological principles include investigating the following variables within the Beltsville long-term Farming Systems Project that compares two conventional and three organic rotations, A) crop performance, B) soil nitrogen dynamics in relation to nitrogen inputs, C) soil carbon sequestration and greenhouse gas flux, D) soil biological community structure in relation to soil quality and production performance, and E) soil erosion and nutrient loss potential. Field experiments to evaluate animal manures and OMRI-approved fertilizers as sources of K and P in organic forage production are in their third year. We have cloned and sequenced five key flowering control genes from eight representative hairy vetch genotypes that differ in flowering time, information that could be used by crop breeders. The automated electronic control system for aeration supply for an in-vessel composting system was brought up to a fully operational status and two test batches were completed. Field studies comparing survival of generic and non-pathogenic strains of E. coli in soils managed organically and conventionally were initiated with poultry litter, dairy manure solids, dairy manure liquid and horse manure to compare baseline responses before composts made of these materials are introduced. Cacao pod husks, an organic residual typically left in the field after cacao beans are harvested, were evaluated as a potential source of compostable feedstock for use in producing an organic fertilizer for cacao farmers. Data are being collected for a third year in permanent weed-free and weedy check plots in organic and conventional systems in the FSP. We are monitoring population and community dynamics and weed-crop competition. A germinable assay is being conducted to determine long-term persistence of weed seedbanks. A University of Maryland student has completed the experimental phase of a project evaluating the influence of long-term soil management on weed-crop competition relationships. Two Master�s students at the University of Maryland are compiling 14 years of data to compare nutrient budgets (C,N,P,K) and evaluate carbon and nutrient management among cropping systems at the long-term FSP. A Brazilian PhD student is characterizing soil carbon fractions collected from diverse FSP systems using near infrared, mid infrared and pyrolysis spectra as part of our effort to evaluate mechanisms of soil carbon sequestration. A scientist from Brazil (EMBRAPA), in association with colleagues at the University of New Hampshire, is comparing output from the DNDC model with two years of soil N2O emissions data to evaluate model predictions. A University of Maryland Master�s student is evaluating the impact of cover crop mixes (rye, hairy vetch) and manure sub-surface banding on soil N2O emissions. The lead scientist is collaborating with scientists from Princeton University to compare a laser based method of measuring atmospheric N2O concentrations with the standard GC method. The lead scientist is collaborating with scientists from the University of Maryland to compare N2O emissions from organically-managed eggplant grown using four different cover crop practices. A visiting Brazilian PhD student is measuring soil N2O emissions following application of a conventional and a newly-designed slow-release nitrogen fertilizer. A high school intern is characterizing short term dynamics of N2O emissions from soil to better characterize factors controlling N2O emissions in the field. Significant Activities that Support Special Target Populations: Members of this project�s research team participated in planning, organizing, and conducting the 13th Annual Future Harvest-CASA Conference, �Farm to Institution: Making Local Food Economics a Reality,� Landsdowne, VA, January 13-14, 2012. This conference targeted small farms, and female and organic producers in the mid-Atlantic area. Minority and disadvantaged farmers in Virginia and North Carolina were the target groups for the 9th Annual Small Farm Family Conference held in Danville, VA on November 1-2, 2011. A project member was instrumental in organizing and planning this conference, and is serving in a similar capacity for the 10th annual �Small Farm Family Conference� to be held in 2012. Members of this project�s research team were instrumental in organizing the 20th Annual Meeting of the Maryland Organic Food and Farming Association on February 18, 2012 in Annapolis, MD. Accomplishments 01 Corn grain yield in a novel cover crop-based, organic rotational no-till corn production system is similar to that in traditional tillage-based systems. Although demand for organic grains is high, traditional tillag based organic corn production practices have restricted the ability of existing producers from expanding their operations due to high labor requirements to manage weeds. Conventional no-till farmers considering transitioning to organic practices are concerned about the amount of tillage required for organic production due to risks of lowering soil quality. Novel rotational no-till organic systems may help alleviate these barriers to expansion of organic acreage. A hairy vetch cover cro coupled with high residue cultivation can provide both weed management a fertility requirements for corn. In a 3-yr field experiment on certified organic land, ARS researchers at Beltsville, Maryland, demonstrated that crop planting date had little effect on corn yield in either tilled or n tilled treatments. Based on plots that received supplemented weed seedbanks, weed competition was the major driver determining corn yield the no-till system, with 50-60% reductions in yield. With high-residue cultivation, yield reduction was still unacceptable at 25%. This work demonstrates to farmers that organic corn grain yield in reduced tillage systems can be similar to that in tillage-based systems when weed seedbanks are not large, and that there is a need to diversify weed management across the entire crop rotation to ensure optimal corn yields This research should help organic farmers reduce labor costs while increasing the conservation benefits of organic corn production. 02 Emissions of N2O, a greenhouse gas, may be reduced by up to 50% in the central and eastern U.S. by reducing N fertilizer application rate to an economic optimum, reducing the proportion of high nitrogen demanding cro within a rotation, and possibly long-term no-tillage. While agricultura soils are the dominant source of nitrous oxide (N2O), a greenhouse gas a catalyst of stratospheric ozone decay, we have a very limited understanding of the impact of various management practices on N2O emissions or on emissions of CH4, another important greenhouse gas. ARS scientists from Beltsville, Maryland and Ames, Iowa summarized recent research findings from the central and eastern U.S., including previousl unpublished data from Beltsville, to show that reducing N fertilizer application rate to an economic optimum, reducing the proportion of high nitrogen demanding crops within a rotation, and possibly long-term no- tillage could reduce N2O emissions by up to 50% in the central and easte U.S. There is insufficient and/or inconsistent evidence indicating whether other proposed N2O mitigation strategies�nitrogen fertilizer and manure timing, placement or source selection, nitrification inhibitors, delayed release fertilizers, or cover crops�provide any mitigation, or what management practices might reduce CH4 emissions or increase CH4 uptake. Additional studies, including long-term studies incorporating sampling strategies that better capture temporal and spatial variability of GHG fluxes and factors controlling this variability, are needed to better quantify the impact of cropland management on GHG emissions. Results show that substantial additional research is needed to provide policymakers with recommendations about best management practices to reduce soil N2O and CH4 emissions from cropland soils. 03 Soil nitrogen availability in no-till soils increases following initiati of no-till such that test results may not be readily interpretable witho considering whether test values have equilibrated or not over time. The influence of no-till (NT) management on soil nitrogen fertility is poorl defined. Many different soil testing procedures have been proposed and tested in search of a useful nitrogen fertility test but a robust soluti to this important problem has remained elusive. Scientists from ARS, along with colleagues from Virginia Tech, sampled soils from farmer fiel that had been in continuous NT for varying lengths of time and analyzed them using diverse soil nitrogen tests. Results indicate that a new equilibrium level for various nitrogen tests had not been reached after years. These results indicate that absolute values for labile soil nitrogen tests may not be readily interpretable with respect to soil fertility recommendations without considering whether these values are changing over time or are at an equilibrium level. In addition, differe patterns of change for different tests indicate that these nitrogen fractions are distinct and may provide different types of information wi respect to quantifying changes in soil fertility with time under no-till Results will help soil scientists develop useful soil nitrogen fertility tests, a goal that has proven elusive for many decades. 04 Cover crops may negatively influence vegetable germination: allelopathic effects of cover crop residues on vegetable crops. Cover crop residues often release allelochemicals (chemicals that reduce germination and seedling growth of plants) that help reduce weed pressure in cropping systems. These chemicals may also inhibit establishment of cash crops because they are not specifically targeted to weedy plants. Sunhemp is tropical legume with significant potential for use as a cover crop in th southeast. Its residues have been shown to suppress weeds but their effects on cash crops are relatatively unknown. Scientists from the Sustainable Agriculture Systems Laboratory in collaboration with University of Georgia scientists evaluated the effects of sunhemp residu and cereal rye residues on weeds and vegetable crops in greenhouse and growth chamber experiments. In the greenhouse study field dried sunnhemp residues reduced germination of lettuce and smooth pigweed (a weed) to t same degree as rye residues. Sunhemp leaves had a greater effect compar to roots. In a second study, water extracts of sunhemp leaves significantly inhibited germination of bell pepper, tomato and onion and reduced turnip and okra germination by 50% while germination of sicklepo a common weed in southern cropping systems, was not affected by the extracts. In addition, root elongation of lettuce, carrot, smooth pigwee and ryegrass was negatively affected by sunhemp leaf extracts. These results indicate that caution should be used when cropping some vegetabl following sunhemp but the residues can also help reduce weed pressure. 05 Biochar source and production conditions influence change in soil water holding capacity. Biochar is produced during the pyrolysis of biomass f the manufacture of biofuels. When added to soil, biochar has potential for long-term sequestration of atmospheric CO2 (the dominant greenhouse gas contributing to global warming) because it is very resistant to microbial decomposition. Additional benefits of biochar include improvi soil nutrient and water availability. However, there is sparse information identifying feedstocks and pyrolysis conditions that maximiz these characteristics. ARS scientists from Florence, SC, Beltsville, MD, and New Orleans, LA along with university colleagues evaluated the effec of several biochars pyrolyzed from different feedstocks at two temperatures on soil-water storage capacity. In general, biochar amendments enhanced the moisture storage capacity of Ultisols and Aridisols, but the effect varied with feedstock selection and pyrolysis temperature. Switchgrass biochars resulted in the greatest increase in potential water holding capacity in the soils compared with the controls Further work is needed to determine the optimum rates of biochar to provide economically useful improvements in water availability. 06 Automatic water level and rate measurement systems need frequent verification to avoid erroneous data. Use of digital electronic hardware and software to automatically monitor environmental variables can improv efficiency of field measurements. However there are few scientific evaluations of field performance, accuracy, reliability and limitations such instruments. We used submerged pressure transducers connected to da loggers to automatically record water levels in streams, rivers, canals, etc., to estimate water flow rate, an important variable in water quanti and quality investigations. Electronically monitored flow rates from a spring and pond at the ARS facility in Watkinsville, Georgia were used t evaluate data integrity over a two year period. Data integrity was ofte but not always sufficient. An extreme case was a period during which average flow rate was underestimated by 17% or underestimated by 29% for the spring, and underestimated by 27% for pond outflow. Users should not assume field sensors, and pressure transducer-based automatic water leve measurement systems in particular, continuously record data correctly. Routine verification of transducer output is crucial to avoid inaccurate (and possibly useless) water level and flow rate estimates. 07 Soil N2O emissions may be impacted by soil microbial community structure Agricultural soils are the dominant source of atmospheric nitrous oxide (N2O), a greenhouse gas catalyst of stratospheric ozone decay. Nitrous oxide emissions are controlled by environmental conditions and soil denitrifying bacteria. Whether differences in denitrifying bacterial community structure impact soil N2O emissions is largely unknown but may be an important factor that is not accounted for in N2O emissions models This research showed that season (spring, summer or fall) and crop plant species (wheat vs. soybean) are the main determinants of denitrification gene abundance. Cropping system, on the other hand, was the main determinant of denitrification gene phylogeny, meaning that regardless o season or crop species the denitrification genes were more closely relat within any particular system than among systems. Results provide a foundation for further investigations into a potential important mechanistic link between soil bacterial community structure and function This information may eventually be integrated into landscape level model used to predict N2O emissions.
Impacts
(N/A)
Publications
- Teasdale, J.R., Mirsky, S.B., Spargo, J.T., Cavigelli, M.A., Maul, J.E. 2012. Reduced-tillage organic corn production in a hairy vetch cover crop. Agronomy Journal. 104:621-628.
- Cavigelli, M.A., Parkin, T.B. 2012. Agricultural management and greenhouse gas flux: cropland management in eastern and central US. In: Liebig, M.A., Franzluebbers, A.J., Follett, R.F., editors. Managing Agricultural Greenhouse Gases. London, England: Academic Press. p. 177-233.
- Novak, J.M., Busscher, W.J., Watts, D.W., Amonette, J., Ippolito, J.A., Lima, I.M., Gaskin, J., Das, K.C., Steiner, C., Ahmedna, M., Rehrah, D., Schomberg, H.H. 2012. Biochars impact on soil moisture storage in an Ultisol and two Aridisols. Soil Science. 177(5):310-320.
- Endale, D.M., Fisher, D.S., Jenkins, M., Schomberg, H.H. 2011. Difficult lessons learned in measuring flow on small watersheds. Applied Engineering in Agriculture. 27(6):933-936.
- Maul, J.E., Mirsky, S.B., Emche, S.E., Devine, T.E. 2011. Evaluating a core germplasm collection of the cover crop hairy vetch for use in sustainable farming systems. Crop Science. 51:2615-2625.
- Mirsky, S.B., Ryan, M.R., Curran, W.S., Teasdale, J.R., Maul, J.E., Spargo, J.T., Moyer, J., Grantham, A.M., Weber, D.C., Way, T.R. 2012. Conservation tillage issues: cover crop-based organic rotational no-till grain production in the mid-atlantic region. Renewable Agriculture and Food Systems. 27(1):31�40. DOI:10.1017/S1742170511000457.
- Evett, S.R., Tolk, J.A. 2009. Introduction: Can water use efficiency be modeled well enough to impact crop management? Agronomy Journal. 101(3) :423-425.
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Progress 10/01/10 to 09/30/11
Outputs
Progress Report Objectives (from AD-416) The long-term research objective of this project is to develop and translate fundamental agroecological knowledge into recommendations and products to improve the economic position of organic farmers and to improve their ability to meet consumer demand for organic products. Objective 1 is to develop component technologies and management strategies that lead to improved productivity, enhanced soil and water conservation, and efficient nutrient cycling on organic farms. Objective 2 is to understand agroecological principles that drive the function of organic cropping systems and quantify ecosystem services. Approach (from AD-416) Approaches to developing component strategies include A) incorporating legumes into organic crop rotations to maximize nitrogen fixation, B) composting that provides a productive and safe amendment for organic agriculture, and C) optimal agronomic practices for managing nutrients and production on organic farms. Approaches to determining agroecological principles include investigating the following variables within the Beltsville long-term Farming Systems Project that compares two conventional and three organic rotations, A) crop performance, B) soil nitrogen dynamics in relation to nitrogen inputs, C) soil carbon sequestration and greenhouse gas flux, D) soil biological community structure in relation to soil quality and production performance, and E) soil erosion and nutrient loss potential. Field experiments to evaluate animal manures and OMRI-approved fertilizers as sources of K and P in organic forage production are in their second year at BARC and fourth year on-farm. Seed increases of Purple Bounty and/or Purple Prosperity hairy vetch varieties facilitated the first field scale trial using these varieties in an organic no-till corn production system. Field trials of eight representative hairy vetch gentotypes from around the world have been initiated on station and on farms. The capacity of biofiltration using wood chips to capture ammonia and odors from force-aerated piles, in-vessel composting, and poultry litter drying process was tested. Biofiltration effectively reduced odorous emissions and significantly increased nitrogen content of the wood chip media in the biofilters from 0.3 to 1.7 percent. Analysis of two years of field data indicate that sidedress, compared to pre-plant, application of organic N fertility sources (i.e., feathermeal, poultry litter, or blended materials) can substantially increase N use efficiency. The fourth year of a field trial evaluating the agronomic performance of organic field corn following a hairy vetch cover crop in tilled vs. no- tilled systems is complete. Results suggest delaying hairy vetch termination to optimize N availability can directly impact growing season duration, weed suppressive potential of surface mulches, and subsequent crop performance. Data are being collected for a second year in permanent weed-free and weedy check plots in organic and conventional systems in the FSP. We are monitoring weed population and community dynamics and weed-crop competition. A germinable assay is being conducted to determine long-term persistence of weed seedbanks. A University of Maryland Master�s student found that the DayCent model was better able to predict annual emissions of N2O, an important greenhouse gas, from the two conventional FSP systems than from an organic system, suggesting that the manure and cover crop modules in DayCent need to be improved to better predict N2O emissions from organic and other systems relying on organic sources of nitrogen. Another University of Maryland Master�s student is compiling 16 years of data collected at FSP to compare nutrient budgets (P, K, N, C) among cropping systems and evaluate nutrient management and soil carbon sequestration. A visiting scientist from Brazil (EMBRAPA) is comparing output from the DNDC model with five years of soil N2O emissions data from FSP and is helping collect a sixth year of N2O and supporting ancillary data. An undergraduate student is helping to conduct research on soil N2O emissions at FSP, supported by the FAR-B Summer Internship Program. A visiting PhD student from Brazil is measuring occluded and free particulate organic matter fractions in FSP soils, as part of our effort to evaluate mechanisms of soil carbon sequestration. We have developed and optimized qPCR and tRFLP methods for FSP soils and are using these methods to quantify and characterize denitrification genes. These data are being compared to measured soil N2O fluxes and other measures of soil microbial community structure. Significant Activities that Support Special Target Populations Members of this project�s research team participated in planning, organizing, and conducting the 12th Annual Future Harvest-CASA Conference, �We are What We Eat: Community Health Through Sustainable Farming,� Reisterstown, MD, January 14-15, 2011. This conference targeted small farms, and female and organic producers in the mid-Atlantic area. Minority and disadvantaged farmers in Virginia and North Carolina were the target groups for the 8th Annual Small Farm Family Conference held in Williamsburg on November 9-10, 2010. A project member was instrumental in organizing and planning this conference, and is serving in a similar capacity for the 9th annual �Small Farm Family Conference� to be held November 2-3, 2011 in Danville, Virginia. Members of this project�s research team were instrumental in organizing a workshop on organic grain production in Queen Anne�s County, Maryland, March 8, 2011. Accomplishments 01 Hairy vetch cultivars from around the world are characterized for important agricultural traits. Hairy vetch is an important nitrogen-fixi cover crop used in organic and other sustainable agriculture production systems. Developing varieties with improved winter survival, earlier blooming, and enhanced nitrogen fixation will increase farmer options fo integrating this important species in their crop rotations. Breeders ne additional information about the genetic potential and variability that exists among hairy vetch accessions globally. Scientists at ARS in Beltsville, Maryland evaluated sixty-four hairy vetch accessions from around the world for flowering date, biomass production, and nitrogen fixation in the field. Genomic marker analysis (AFLP) shows great diversity among accessions and biogeographical linkages among accessions from the same country of origin. This information will be essential for breeders developing improved hairy vetch varieties, and for producers in identifying optimum varieties for implementing use of this important nitrogen-fixing cover crop. 02 Plant available nitrogen provided by soils increases with increasing cro rotation length in organic systems and is greater in organic than conventional systems. Increasing the proportion of a crop�s nitrogen needs met by mineralization of soil organic N reduces dependence on external N inputs required for crop production. Nitrogen fertilizer production, transport and application represent about 30% of energy use agriculture. Scientists at ARS in Beltsville, Maryland characterized so organic N fractions from five long-term cropping systems. They found th total soil organic N was similar among three organic systems and a conventional no-till system, and was significantly greater than in a conventional chisel-till system. Particulate organic matter�N, a fractio of soil organic N that is readily mineralized, and mineralizable organic soil N were both greatest in the organic systems and least in convention systems. Among the organic systems, particulate organic matter�N increas with increasing crop rotation length and mineralizable N was greater in three and six year crop rotations than in a two year crop rotation. The results provide important strategies to reduce N inputs in agricultural systems that will be useful to all farmers, extension educators, nutrien management plan writers, and others interested in sustainable soil fertility management. 03 Feather meal and feather meal-poultry litter blends show potential as si dress fertilizers to improve nitrogen use efficiency in organic systems. Improving nitrogen use efficiency in corn production will provide econom benefits to farmers and environmental benefits to society. Researchers ARS in Beltsville, Maryland showed that the N release characteristics of locally available sources of OMRI-approved N (raw poultry litter, pelletized poultry litter, feather meal, and a pelletized blend of feath meal and poultry litter) could serve as viable sources of supplemental N for organic and other grain production. The rate of N release of each material was relatively fast, suggesting that applying them to corn at t V5 growth stage (sidedress) could result in significant improvements in use efficiency compared to pre-plant applications (the industry standard Results showed that the feather meal and the feather meal-poultry litte blend were more nutrient dense than the raw and pelleted poultry litter and therefore less costly to transport per unit of available N. This information will benefit producers, extension educators, nutrient management plan writers, and others interested in improved soil fertilit and nutrient management in organic and other grain cropping systems.
Impacts
(N/A)
Publications
- Spargo, J.T., Cavigelli, M.A., Mirsky, S.B., Maul, J.E., Meisinger, J.J. 2011. Mineralizable soil nitrogen and labile soil organic matter in diverse long-term cropping systems. Nutrient Cycling in Agroecosystems. 90:253-266.
- Ullrich, S.D., Buyer, J.S., Cavigelli, M.A., Seidel, R., Teasdale, J.R. 2011. Weed seed persistence and microbial abundance in long-term organic and conventional cropping systems. Weed Science. 59:202-209.
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Progress 10/01/09 to 09/30/10
Outputs
Progress Report Objectives (from AD-416) The long-term research objective of this project is to develop and translate fundamental agroecological knowledge into recommendations and products to improve the economic position of organic farmers and to improve their ability to meet consumer demand for organic products. Objective 1 is to develop component technologies and management strategies that lead to improved productivity, enhanced soil and water conservation, and efficient nutrient cycling on organic farms. Objective 2 is to understand agroecological principles that drive the function of organic cropping systems and quantify ecosystem services. Approach (from AD-416) Approaches to developing component strategies include A) incorporating legumes into organic crop rotations to maximize nitrogen fixation, B) composting that provides a productive and safe amendment for organic agriculture, and C) optimal agronomic practices for managing nutrients and production on organic farms. Approaches to determining agroecological principles include investigating the following variables within the Beltsville long-term Farming Systems Project that compares two conventional and three organic rotations, A) crop performance, B) soil nitrogen dynamics in relation to nitrogen inputs, C) soil carbon sequestration and greenhouse gas flux, D) soil biological community structure in relation to soil quality and production performance, and E) soil erosion and nutrient loss potential. A field experiment to evaluate animal manures and OMRI-approved fertilizers as sources of K and P in organic forage production was established at BARC; a similar on-farm experiment is in its third year. Data are being collected on forage yield and quality, and soil fertility. Sixty-four hairy vetch accessions from around the world are being evaluated for flowering date, biomass production, and nitrogen fixation in the field. Genomic marker analysis (AFLP) shows great diversity among accessions and biogeographical linkages among accessions from the same country of origin. Seed increases of Purple Bounty and/or Purple Prosperity through MTAs with private seed companies facilitated the first field scale trial using these varieties in an organic no-till corn production system. A postdoctoral associate is conducting a second year of field research to address nitrogen availability in organic grain crops. Initial results indicate that soil nitrogen mineralization is substantially greater in organic than conventional cropping systems, and that sidedressing organic materials provides a yield boost to corn compared to applying materials at planting. A four year field trial evaluating the agronomic performance of organic field corn following a hairy vetch cover crop in tilled vs. no-tilled systems is in its final year. Preliminary results suggest delaying hairy vetch termination to optimize N availability can directly impact growing season duration, weed suppressive potential of surface mulches, and subsequent crop performance. Permanent weed-free and weedy check plots were established in organic and conventional systems in the FSP. We are monitoring population and community dynamics and weed-crop competition, and a germinable assay is being conducted to determine long-term persistence of weed seedbanks. Total soil carbon and nitrogen data to a depth of 1 m are being interpreted in light of carbon and nitrogen inputs to soil in the diverse FSP systems. Soils from FSP are also being evaluated for occluded and free particulate organic matter fractions, as part of our effort to evaluate mechanisms of soil carbon sequestration. A Master�s student at Hood College completed their thesis on the global warming potential of FSP cropping systems under the direction of the project�s lead scientist. We are using soil texture data collected at 748 spatially explicit locations at the FSP site to identify sampling locations to measure soil biological properties. We have developed and optimized qPCR and tRFLP methods for FSP soils and are using these methods to quantify and characterize denitrification genes. These data are being compared to measured soil N2O fluxes and other measures of soil microbial community structure. Significant Activities that Support Special Target Populations Members of this project�s research team participated in planning, organizing, and conducting the 11th Annual Future Harvest-CASA Conference, �Rebuilding the Real Economy: Nourishing Local Foods and Farmers� that was held in Shepherdstown, West Virginia, January 15-16, 2010. This conference targeted small farms, and female and organic producers in the mid-Atlantic area. Minority and disadvantaged farmers in Virginia and North Carolina were the target groups for the 7th Annual Small Farm Family Conference held in Richmond, Virginia, November 9-10, 2009. A project member was instrumental in organizing and planning this conference, and is serving in a similar capacity for the 8th annual �Small Farm Family Conference� to be held November 9-10, 2010 in Williamsburg, Virginia. Members of this project�s research team were instrumental in organizing a workshop on organic grain production in Queen Anne�s County, Maryland, March 9, 2010 and a workshop on organic vegetable production in Baltimore County, Maryland, June 16, 2010. Accomplishments 01 Feather meal and feather meal-poultry litter blends show potential as si dress fertilizers to improve nitrogen use efficiency in organic systems. Improving nitrogen use efficiency in corn production will provide econom benefits to farmers and environmental benefits to society. Researchers ARS in Beltsville, Maryland showed that the N release characteristics of locally available sources of OMRI-approved N (raw poultry litter, pelletized poultry litter, feather meal, and a pelletized blend of feath meal and poultry litter) could serve as viable sources of supplemental N for organic and other grain production. The rate of N release of each material was relatively fast, suggesting that applying them to corn at t V5 growth stage (sidedress) could result in significant improvements in use efficiency compared to pre-plant applications (the industry standard Results showed that the feather meal and the feather meal-poultry litte blend were more nutrient dense than the raw and pelleted poultry litter and therefore less costly to transport per unit of available N. This information will benefit producers, extension educators, nutrient management plan writers, and others interested in improved soil fertilit and nutrient management in organic and other grain cropping systems. 02 Weed seed persistence is similarly short for organic and conventional cropping systems. Crop yield loss from competition with weeds is particularly troublesome for organic farmers because of the inability to use herbicides for controlling weeds. It has been hypothesized that organic systems may be more resilient to spikes in weed seed production because weed seed in soil should be less persistent in high organic matt soils with high microbial activity that are characteristic of organic farms, compared to seed in conventionally managed soils. Comparison of weed seed persistence in organic and conventional soils in two long-term cropping systems experiments conducted by ARS, Beltsville, and Rodale Institute, Kutztown, Pennsylvania, showed that weed seed persistence was relatively short (half-life of approximately one year) and that there we only small differences (a couple of months) in half-life between organic and conventional systems. In addition, seed persistence half-life correlated poorly with various measures of soil microbial activity and organic matter content. Results suggest that more precise mechanistic hypotheses will be needed for defining factors responsible for weed seed longevity in soil.
Impacts
(N/A)
Publications
- Teasdale, J.R., Cavigelli, M.A. 2010. Subplots facilitate assessment of corn yield losses from weed competition in a long-term systems experiment. Agronomy for Sustainable Development. 30:445-453.
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Progress 10/01/08 to 09/30/09
Outputs
Progress Report Objectives (from AD-416) The long-term research objective of this project is to develop and translate fundamental agroecological knowledge into recommendations and products to improve the economic position of organic farmers and to improve their ability to meet consumer demand for organic products. Objective 1 is to develop component technologies and management strategies that lead to improved productivity, enhanced soil and water conservation, and efficient nutrient cycling on organic farms. Objective 2 is to understand agroecological principles that drive the function of organic cropping systems and quantify ecosystem services. Approach (from AD-416) Approaches to developing component strategies include A) incorporating legumes into organic crop rotations to maximize nitrogen fixation, B) composting that provides a productive and safe amendment for organic agriculture, and C) optimal agronomic practices for managing nutrients and production on organic farms. Approaches to determining agroecological principles include investigating the following variables within the Beltsville long-term Farming Systems Project that compares two conventional and three organic rotations, A) crop performance, B) soil nitrogen dynamics in relation to nitrogen inputs, C) soil carbon sequestration and greenhouse gas flux, D) soil biological community structure in relation to soil quality and production performance, and E) soil erosion and nutrient loss potential. Significant Activities that Support Special Target Populations Progress was made on component studies that make up Objective 1 and on all hypotheses related to the long-term Farming Systems Project that are part of Objective 2. For example, a component experiment was completed in fall of 2008 to determine the importance of planting date, tillage, and weed management on corn grown in a hairy vetch cover crop (Hypothesis 1.C1). Results of this experiment indicate that delayed planting did not improve weed management but that planting into a disked seedbed reduced weed biomass and increased post-planting cultivation efficiency compared to planting into a rolled vetch no-tillage seedbed. In addition, a postdoctoral associate was hired and has initiated field and laboratory research to address nitrogen availability in organic grain crops as outlined in Hypotheses 1.C1, 1.C2, and 2.B. We have also continued collecting and analyzing core data on the FSP including developing an algorithm based on short-term N2O flux patterns to interpolate N2O flux values for dates between actual sampling dates. We installed a wireless sensor network at FSP to collect near-continuous soil moisture and temperature data in collaboration with Johns Hopkins University scientists. We also continued on-farm research to develop best management practices for soil fertility under organic management practices and were awarded two OREI grants (> $3 million total) to conduct on-farm research to improve soil fertility and weed management on organic grain farms in the mid-Atlantic region. Significant Activities that Support Special Target Populations Members of this project�s research team participated in the planning, organization, and conduct of the �Farming for Profit and Stewardship Conference� that was held in Frederick, Maryland, January 16-17, 2009. This conference targeted small farms with female and organic producers in the mid-Atlantic area. Minority and disadvantaged farmers in Virginia and North Carolina were the target groups for a conference held at the Institute for Advanced Learning and Research in Danville, Virginia, November 5-6, 2009. An FSP member was instrumental in organizing and planning this conference, and is serving in a similar capacity for the fourth annual �Small Farm Family Conference� to be held November 9-10, 2009 in Richmond, Virginia. Members of this project�s research team were instrumental in organizing a workshop in Queen Anne�s County, Maryland, March 17, 2009. Technology Transfer Number of Active CRADAS: 1 Number of New/Active MTAs(providing only): 6
Impacts
(N/A)
Publications
- Cavigelli, M.A., Hima, B.L., Hanson, J.C., Teasdale, J.R., Lu, Y. 2009. Long-term economic performance of organic and conventional field crops in the mid-Atlantic region. Renewable Agriculture and Food System. 24:102-119.
- Teasdale, J.R., Abdul Baki, A.A., Park, Y. 2008. Sweet corn production and efficiency of nitrogen use in high cover crop residue. Agronomy for Sustainable Development. 28:559-565.
- Cavigelli, M.A., Dao, T.H. 2008. Residual impact of raw and composted poultry litter on soil carbon pools. Electronic Journal of Integrative Biosciences [serial online]. 6:30-40. Available: http://clt.astate. edu/electronicjournal/Articles.htm.
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