Progress 01/01/04 to 12/31/08
Outputs
OUTPUTS: Water-stable aggregates (WSA) are a measure of soil structure and are promoted by soil binding roots and fungi. We hypothesized that WSA would be higher in soils under perennials (PR) and double-cropped small grains (SG) than in soils under summer annuals in annual systems (SAa), and summer annuals in perennial and diverse systems (SAp). We sampled soils of 10 crops from four 36-year-old systems: two annual systems: continuous corn, corn-soybean, a perennial system: 4yr corn-4yr alfalfa; and a diverse system: corn-oats-wheat double-crop- 2yr red clover timothy. WSA under PR, SG and SAa were significantly higher than under SAa; SAp did not differ significantly from the PR and SG, indicating a more pronounced cropping system effect than individual crop-effect. WSA varied more under summer annuals than PR and SG from spring to autumn. Estimated live-root period predicted WSA best with soil water content and SMBC. Results suggest that cropping systems with longer live-root periods can promote WSA with time. We studied corn yields over a 16-yr in the 4 cropping systems. Fertility regimes were inorganic, or manure based on crop N- or P-needs. Mean corn yields in 4C4A and COW2RT were 10-12% higher than CC and 7% higher in 4C4A than CS. Yield trends did not differ among the 4 treatments over time. Coefficient of variation analysis indicated that yield variability was highest in CC and lowest in 4C4A across fertility regimes. According to regression stability analysis, response of corn yields to the environment mean did not differ among the 4 cropping systems within inorganic and P-based manure fertility. Under N-based manure fertility, yields were less stable in CC than other systems; yields diverged in the poorest-yielding year but converged in the highest-yielding year. Precipitation in July, May and June explained 64% of yield variability. In a PA survey of ground beef, finishing cattle in for 2 months on 100% pasture or pasture plus stored forages (P+SF) resulted in ground beef with 240% higher omega-3 fatty acids and 90% higher conjugated linoleic acid (CLA) concentrations compared to cattle finished on grain and stored forages (G+SF) in PA and typical retail ground beef. Even though beef from P+SF was 38% lower in fat, a serving of ground beef from the PAST and P+SF groups had 183% more omega-3 fatty acids. Total quantity of CLA did not differ significantly among the 4 groups in a 85 g serving. Tools to help organic producers manage nutrients were identified and developed: soil & compost analysis reports, a fact sheet, and computer software to monitor nutrient budgets. A survey of U.S. teaching farms revealed numerous educational benefits that ranged from specific knowledge and skills to higher order learning, and personal development. Project results have been shared with farmers, educators, and researchers via 3 grower and educator meetings, 5 workshops, 7 scientific meetings, and individual reports to participants of the beef survey. Products include a doctoral dissertation, MS thesis, 4 manuscripts for scientific journals, 1 book chapter, a fact sheet, and 8 published abstracts. PARTICIPANTS: Heather Karsten, project leader, originator of ideas, funds and student supervision. Collaborators included: Douglas Archibald, Gregory Roth, Sjoerd Duiker, MaryAnn Burns, David Eissenstat, Tracy Hoover, Nancy Ellen Kiernan, Graduate students: Kulbhushan Grover, Amy Lassen, Edly Santiago-Andino, Elsa Sanchez, Tom Richard, Richard Stehower TARGET AUDIENCES: Agronomic farmers in PA and the Northeast, pasture-based livestock producers in Pennsylvania and the Northeast, groups include members of NE Pasture Consortium, PA Project Grass, PA Association for Sustainable Agriculture, Northern Tier Sustainable Meats Cooperative, Organic farmers (crop, vegetable, diversified livestock) in the Northeast, Residential students of agricultural sciences PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Results of the project produced scientific understanding of cropping system practices that promote soil water stable aggregates, corn grain yields and yield stability, increase healthful fats in ground beef, as well as tools to assist organic growers with nutrient management. The project enhanced our understanding of the educational value of experiential learning, the nature and strategies of U.S. student teaching farms, and strategies to manage and sustain student teaching farms. Individual growers reported to us that they used the summarized results and their product results of the nutritional analysis of Pennsylvania cattle finished on pasture and pasture and stored forages to market their beef. Results enhanced agronomy extension faculty and residential faculty understanding, and contributed to educational presentations that discuss practices to promote soil aggregate stability, corn yield, and yield stability. A new course "Principles and practices of Organic Agriculture" was developed. Invited talks were presented to the Pennsylvania Project Grass 2008 Grazing Lands conference, West Virginia Beef Producers from the Farm Bureau (2008), and the Northeast Pasture Consortium 2008. Extension presentations on Using Organic Nutrient Sources and Interpreting Soil and Compost Analyses are in planned for Winter 2009.
Publications
- Grover, K.K. 2008. Long-Term Cropping Systems Effects On Soil Aggregate Stability, Corn Grain Yields, And Yield Stability. Ph.D. Thesis. The Pennsylvania State University, University Park, PA. 141 pp.
- Lassen. A. 2008. Fatty acids in beef marketed in Pennsylvania from cattle finished on pasture or stored feeds. M.S. Thesis. The Pennsylvania State University, University Park, PA. 69 pp.
- Grover, K. K. and H. D. Karsten. 2008. Yield stability of corn grain yields in long-term cropping systems. Agronomy J. (Submitted).
- Karsten, H.D. and D. J. Baer. 2008. Grass and Human Nutrition. In Grass 2008: Our Growing Resource. Ed. Walter Wedin and Steven Fales. ASA-CSSA-SSSA, Madison, WI. (In Press).
- Karsten, H.D., K. Bullington, and N.E. Kiernan. 2008. Survey of US Students Teaching Farms and their Educational Value. In Annual meetings abstracts ASA, CSSA, and SSSA. Madison, WI. 5-9 Oct., 2008. Houston, TX. 530-4 CD-ROM.
- Sanchez, E. and T. Richard. 2008. Using organic nutrient sources. College of Agricultural Sciences Fact Sheet. The Pennsylvania State University. (In Press.)
- Lassen, A., H. D. Karsten, and D. D. Archibald. 2008. Fatty acids in Pennsylvania-marketplace beef from cattle fed a pasture-based diet or stored feeds. Meat Science. (Submitted).
- Lassen, A., H. D. Karsten, and D. D. Archibald. 2007. Comparison of fat-soluble vitamin levels in ground beef from cattle finished on pasture or stored feeds. Annual Meeting, American Society of Agronomy Northeastern Branch. University Park, PA. June 24-26, 2007. pg. 65.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: We studied how summer annual crop systems with perennials and double-cropped small grains influenced soil aggregate stability, and crop yield stability. We compared soil from 4 crop systems (annual, annual-perennial, & diverse) of a 36-year old crop system experiment. Annual systems were continuous corn and a corn-soybean rotation; the annual-perennial system had 4 years of corn and 4 years of alfalfa, the diverse system was corn, double-cropped oats and winter wheat in year 2, then autumn planted red clover and timothy hay for 2 years. The experimental design was a randomized complete block design with 4 blocks. In May, July, August, and November 2005 we measured water stable aggregates of the soil (WSA). Analysis of variance (ANOVA) with repeated measures was conducted on the data, with main effects: crops nested in rotation, crop systems as fixed effects, blocks as random and dates as repeated measures. We also defined 6 variables based on live root presence and soil
disturbance frequency among the crops and cropping systems for regression analysis. Cropping systems influenced WSA more than crops alone. In perennial and double-cropped small grains, WSA was 80-140% higher than summer annuals in the annual systems, but was similar to the summer annuals in the perennial and diverse systems. In summer annuals, WSA changed more among seasons than in the perennial and double-cropped small grains. Proportion of time of a cropping system with live roots predicted WSA best and was positively associated with WSA. We also compared corn yields and conducted yield stability analysis on corn yields over the last 16 years in the 4 crop systems under three fertility regimes (inorganic fertilizer or manure based on crop P or N needs). Corn yields averaged 7-12% higher in the perennial and diverse systems than annual systems; yields varied most under continuous corn and least in the perennial systems. With nitrogen-based manure, monoculture corn yields were least
stable and were lowest in the low-yielding years relative to the other crop systems. In another study, we compared the omega-3 fatty acids (FAs), the ratio of omega-6:omega-3 FAs, and conjugated linoleic acid (CLA) concentration of pastured and retail ground beef marketed in Pennsylvania. We collected ground beef in summer and autumn 2006 from PA farms that finished beef on; i) pasture, ii) pasture and stored feed), or iii) stored feeds only. We purchased ground beef from PA retail markets (assumed to be finished on grain). We used gas chromatography to analyze the FA profile of the beef fat. ANOVA was conducted on the FA concentrations with feeding strategy & season as fixed variables, and sources nested in feeding strategy as random. Omega-3 FAs in ground beef from pasture groups was almost 4 fold higher than retail beef and twice as high as PA-stored feed beef. CLA in pasture groups was 2 fold higher than PA-stored feed and retail beef. Ratio of omega-6:omega-3 in ground beef from
pasture groups was more than 5 fold lower than the retail group, and 4 fold lower than the PA-stored feed group. A survey was also conducted to evaluate the nature and educational value of student teaching farms.
PARTICIPANTS: Kulbhushan Grover, Agronomy graduate student; Amy Lassen, Agronomy graduate student; Gregory Roth, grain crop production, Department of Crop and Soil Sciences, Douglas Archibald, analytical chemist, Department of Crop and Soil Sciences, conducted fatty acid analyses; Marvin Risius, Emeritus, Department of Crop and Soil Sciences Statistical Consulting, Pennsylvania Association for Sustainable Agriculture, assisted with identifying Pennsylvania beef pasture-based beef producers
TARGET AUDIENCES: Agronomic growers, agronomic extension educators, NRCS; beef producers in Pennsylvania, Pennsylvania consumers
Impacts
We documented that after 36 years, soil aggregate stability was improved in cropping systems that had live roots present in the soil for a high proportion of year. Inclusion of perennials and double-cropped small grains in the annual cropping systems improved percent water stable aggregates with less seasonal variability. Cropping systems had a more pronounced cumulative effect than crops on percent water stable aggregates. Perennial and diverse crop rotations also produced higher average corn yields than annual systems. Further, corn yields were less variable in the perennial systems compared to the continuous corn, and in the nitrogen-based manure treatment corn yields were in continuous corn were less stable and lower in poor-yielding years than in the other cropping systems. We found that "pasture-finished" beef that was available to Pennsylvania consumers had higher concentrations of Omega-3 fatty acids and conjugated linoleic acid, and a lower ratio of
omega-6:omega-3 fatty acids than beef finished on stored feed or sold in retail markets.
Publications
- Grover, K., H. D. Karsten, G. Roth, and M. Risius. 2007. Long-term Effects of Cropping Systems on Corn Grain Yields. In Annual meetings. ASA, CSSA, and SSSA, New Orleans, LA: Nov. 4-8. Abstract 65-10. CD ROM.
- Lassen, A., H. D. Karsten, and D. D. Archibald. 2007. Comparison of fatty acids in ground beef from cattle fed on pasture or stored feed. In Annual meetings abstracts. ASA, CSSA, and SSSA, New Orleans, LA Nov. 4-8. Abstract 270-8. CD ROM.
- Grover, K.K. and H.D. Karsten. 2007. Long-term effects of cropping systems on soil aggregate stability. Annual Meeting, American Society of Agronomy Northeastern Branch, June 24-26, University Park, PA. p.7.
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Progress 01/01/06 to 12/31/06
Outputs
Research indicates that live roots and reduced disturbance as associated with perennial crops can promote soil aggregate stability. Therefore, we hypothesize that including perennials and double cropping with small grains in crop rotations with summer annuals will improve soil aggregate stability, soil and bulk density. To test the hypothesis, we are comparing soil sampled from four cropping systems (annual, annual-perennial, & diverse cropping systems) of a 36-year old cropping systems experiment. Annual systems were continuous corn and corn-soybean rotation; the annual-perennial system was 4 years of corn followed by 4 years of alfalfa, the diverse system sequence was corn, oats and wheat in year 2, then autumn planted red clover and timothy hay grown for 2 years. The experimental design was a randomized complete block design with 4 replications. In May, July, August, and November 2005 we measured soil temperature and bulk density in the field, and collected samples
to measure water stable aggregate stability, soil carbon, and soil microbial biomass carbon in the laboratory. We measured water infiltration in August. We are comparing the soil properties under the summer annuals, winter small grains, and perennials within and across the rotations. Analysis of variance with repeated measures was conducted on the data with the main effects: crop nested in rotation, crop rotation, and dates, and the interaction of the main effects. Initial results for percent water stable aggregates (WSA) indicate that the interaction of crop by season is significant. We separated the data into two parts: spring to summer and summer to autumn. In the spring, soil under the corn in the diverse rotations and annual-perennial rotations was higher than under the annual systems. However, within the diverse rotation, the WSA of the soils of perennials and small grains were similar to corn. Results thus far, suggest that perennials and double-cropped small grains had a
long-term positive effect on soil aggregate stability. We are continuing to analyze other soil properties and preparing to conduct historical corn yield analyses.
Impacts
We documented that after 36 years, crop rotations that include perennials and double-cropped small grains with summer annual crops had higher soil water stable aggregation.
Publications
- Grover, K. and Karsten, H.D. 2006. Long-term Effects of Cropping Systems on Soil Aggregate Stability. World Congress of Soil Science, Philadelphia, PA. July 2006. p 1536a
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Progress 01/01/05 to 12/31/05
Outputs
Research indicates that live roots and reduced disturbance as associated with perennial crops can promote soil aggregate stability. We hypothesized that including perennials and small grains in crop rotations with summer annuals would improve soil aggregate stability better than summer annuals in rotations, and soil aggregation would be higher in summer when more roots are present compared to fall or spring. We studied 10 crops from within 4 cropping systems of a 36-year old cropping systems experiment. The experimental design was randomized complete block design with 4 replications. We grouped the cropping systems into types (annual, annual-perennial, & diverse systems); and the crop into types: summer annuals, winter small grains, and perennials. Annual systems were continuous corn and corn-soybean rotation; the annual-perennial system was 4 years of corn followed by 4 years of alfalfa, the diverse system sequence was corn, oats wheat in year 2, then autumn planted
red clover and timothy hay grown for 2 years. Twelve soil cores of 7.5 cm diameter were collected at 15 cm depth from each crop plot in the spring (25 May), summer (13 July, 22 August), and fall (31 October) of 2005. Percent water stable aggregates greater than 250 um (WSA) were measured with the standard wet sieving, slaking technique. Gravimetric moisture content, water potential, soil bulk density, and microbial biomass carbon were also measured. Data were statistically analyzed in split plot design with time as main plots and crops as sub-plots using ANOVA of SAS. Means were compared using Tukey's test (p< 0.05). Soils of perennials and small grains did not always have higher WSA than summer annuals. Soil of corn in the diverse system had similar WSA than perennials and small grains. Soils of perennials and small grains had two fold higher WSA than summer annuals in the annual systems and 1.3 fold higher WSA than year 4 of corn in the annual-perennial system. When we compared
soils of summer annuals, WSA of the corn soil in the annual-perennial and diverse systems was 120 and 60% higher respectively than WSA of summer annuals in annual systems. This indicates that perennials and small grains had a long-term positive effect on soil aggregate stability. In soil of year 4 corn WSA decreased from year 4 alfalfa. However, WSA in corn soil of the diverse system did not decrease from the perennial and small grains. The WSA changed significantly with the seasons; it increased from spring to summer by 34% and then decreased in fall by 35%. Inclusion of perennials and small grains improved soil water stable aggregation of all crops in the rotations, compared to the annual systems. Water stable aggregation was highest in the summer when root biomass was probably highest. We are analyzing the other soil properties and will conduct historical corn yield analyses. A summer intern worked on a commercial crop farm that practices no-till and cover-cropping. He measured WSA
from fields that had been no-tilled and cover cropped for 3, 23 and 30 years. Fields that had been no-tilled and cover cropped 3 years had significantly lower WSA than the fields managed similarly for 23 and 30 years
Impacts
We documented that after 36 years, soil water stable aggregation differed among rotations and crops. Inclusion of perennials and small grains improved soil water stable aggregation of all the crops in the rotations, compared to the annual systems of summer annuals alone. Water stable aggregation was highest in the summer when root biomass was probably highest and lowest in the spring and fall.
Publications
- No publications reported this period
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Progress 01/01/04 to 12/31/04
Outputs
To evaluate experiential learning, whole systems curriculum, and begin to identify practices that are important for farming system sustainability and profitability in Pennsylvania,12 undergraduate interns spent 12 weeks in the on-farm agroecology internship supported by an interdisciplinary faculty team. The faculty team provided a week orientation to agroecology and on-farm research. In pairs, interns then worked on a farm for 10 weeks. Interns answered weekly guided journal questions that required interviewing farmers, & collecting data about farm components and management practices (including crop and soil management, weeds, insects, labor, farm economics and marketing, and social values). Journal questions also addressed reasoning and critical thinking required to gather, apply, analyze, synthesize, & evaluate information. Faculty and interns together visited all host farms twice during the farm stay. Students spent a final week at Penn State University developing
descriptive whole farm case studies, research analyses and projects. Technical questionnaires before and after the internship indicated that students understanding of agroecology significantly improved during the on-farm internship. Common farming management practices identified included: i) conserving soil and nutrients with cover crops, perennials, reduced tillage, compost, and manure, ii) use of crop rotation and biodiversity; iii) production of high-value products and marketing to high-value markets, iv) balancing profitability and environmental stewardship. A pre-then-post evaluation model indicated that students' abilities to solve problems and think critically was enhanced. A common challenge across the farms was identifying dependable labor and managing labor. The agroecology on-farm instructional materials are available for educational use at the project website: http://PAonfarminterns.cas.psu.edu. In a follow-up survey, 92% of the interns reported that the internship
influenced their career plans, 50% reported that it influenced their educational plans. Half of the interns had graduated from college and all are working in agriculture or an agriculture-related career. Faculty reported that participation in the program provided opportunities to have new experiences with colleagues outside of their area of expertise, and to obtain new knowledge. Five of six participating faculty reported that participation in the on-farm internship influenced their research. All participating faculty have used some of the educational materials in their teaching or extension education programs. In addition, field research is underway to quantify the annual and perennial agronomic crop residues and root turnover contributions to soil organic matter, soil biological diversity, soil physical properties and crop yield stability after 20 years of various crop rotations. Root turnover and crop residues of both annual and perennial agronomic crops will be quantified annually
for 2 years.
Impacts
The interns and faculty participating in the agroecology on-farm internship program gained a better understanding of how farmers manage from a whole farm perspective.Students'gained a greater technical understanding of agroecology and students'abilities to solve problems and think critically was enhanced.Common successful farm management practices were identified including:i)conserving soil and nutrients with cover crops, perennials, reduced tillage, compost, and manure, ii)use of crop rotation and biodiversity;iii)production of high-value products and marketing to high-value markets,iv)balancing profitability and environmental stewardship. A common challenge across the farms was identifying dependable labor and managing labor. Instructional materials, research project results, and experiential essays that the interns created are available for educators to use at the project website: http://PAonfarminterns.cas.psu.edu. Ninety-two percent of the interns reported that
the internship influenced their career plans, and 50% reported that it influenced their educational plans. All of the interns who have graduated from college are working in agriculture or an food systems-related career. Faculty reported that participation in the program provided opportunities for new experiences with colleagues outside of their area of expertise, and to obtain new knowledge. Five of six participating faculty reported that participation in the program influenced their research. All participating faculty have used some of the educational materials in their teaching or extension education programs.
Publications
- Karsten, H.D.,Santiago-Andino, E., Hoover, T., Fleischer, S., Bruns, M. A., Mortensen, D., Hyde, J., Lamont, W. 2004. Understanding Whole Farm Agroecology through Experiential Learning. 2004 ASA-CSSA-SSSA International Annal Meetings with the Canadian Society of Soil Science. Seattle, Washington, Oct. 31-Nov.4, 2004. Abstract #6256.
- Karsten, H. D., Hoover, T., and Santiago, E. 2004. Using experiential learning to enhance knowledge about sustainable whole farm systems. North American Colleges and Teachers of Agriculture 2004 Conference, University of Florida, Gainesville, FL June 21-23. pp.64
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