Growing continuous corn conventionally without organic amendments reduces soil health, corn production and growers’ profits. Partnering with Mr. Dan Hunsicker, a corn grower in Pennsylvania, a research study determined if the application of organic amendments in addition to synthetic fertilizer and pesticides would increase soil health, corn biomass, and grain yield. The organic amendments were compost (C), compost extract (E) and compost + compost extract (CE) compared to synthetic fertilizer and herbicides only (S). Results showed bulk density was lower in the CE treatment compared to the S treatment (1.35 versus 1.45 g per cubic cm). Mean soil organic matter percentage was significantly (P= 0.0385) higher in the CE treatment (3.41%) than the S, E and C treatments (3.07, 2.96, and 2.91 %, respectively). Plant dry weight in S treatment was 21,237 kg per ha followed by C, CE, and E (20,974, 20,408, and 20,382 kg per ha, respectively). Corn grain yield was slightly higher with compost [(11,501 kg per ha (183.37 bu per acre)] but not significantly different from yields in E, CE or S treatments (11,441, 11,094, and 10,861 kg per ha or 182.43, 176.89 or 173.16 bu per acre, respectively). Because the grain yield increase could translate into $165,000 in revenue for his 3000-acre farm, Mr. Hunsicker intends to retrofit his equipment for compost and compost extract application. Seven interns were trained on soil and plant sampling and processing, and three technicians participated in compost extract preparation and application. Project information was presented to ~150 people at the Rodale Institute Research Farm’s Annual Field Day in Kutztown, PA on July 19, 2013 and a poster session at the American Society of Agronomy Conference on November 4th, 2014 in Long Beach, California. A web article was developed and will be posted on Rodale’s Institute website in January 2015.
There were 908,753 acres cropped to corn in Pennsylvania (Agricultural Census, 2008). Corn is used for humans, livestock, and pet food. Dan Hunsicker, a Pennsylvania corn grower, is interested in increasing corn grain yield for the specialty dog and cat food market. Intensive cultivation and continuous production of corn year after year on same land reduces soil health, corn yield and consequently growers’ profits. Growers are always looking for practices that enhance crop yield and quality, profitability and sustainability of their livelihood.
The mission at Rodale Institute is to improve the health and well-being of people and the planet through practical information verified by research. Rodale Institute has a compost facility that produces high-quality compost from wood chips, manure, straw, and vegetable wastes. These composts are monitored for temperature and moisture and turned as needed to allow aeration. The diversity of compost components provide greater quality than those prepared from one or two components. The use of organic amendments, such as compost and compost extract, prepared with greater quality, has not been tested on growers’ farms and under growers’ management practices on a large scale. The partnership created in this project was specifically designed to evaluate whether organic amendments would increase kernel production and soil health in large-scale production agriculture and if these amendments could be integrated into the growers’ management system. Project data is anticipated to increase compost and compost extract use in conventional production systems by demonstrating improvements in soil health and higher yields. This project also will be a cornerstone in developing and designing additional research and educational projects to address the production and environmental quality needs of Pennsylvania growers.
Study objectives were to:
- measure shifts in pH, EC, nutrient content, and soil biology (total and active bacteria, fungi, nematodes and protozoa) during compost production,
- determine if organic amendments increase soil organic matter and decrease bulk density,
- quantify corn biomass and kernel yield,
- measure nutrient content in plant material, and
- demonstrate how to incorporate organic amendments into large-scale conventional agriculture.
Throughout the study, we were able to meet the following performance targets:
- Field study was established scientifically.
- High-quality, biologically-active compost and compost extract was produced and applied.
- Interns and staff were trained on assessing compost and compost extracts under the microscope for biological organisms and compost application.
- Soil samples were collected for bulk density and soil organic matter analysis.
- Plant biomass and grain yield were measured.
- Fields were harvested to calculate total grain yield per treatment.
- Project objectives and results were shared with about 150 people who attended our annual on-farm field day at the Rodale Institute Research Farm on July 19, 2013 and the poster session at the American Society of Agronomy Conference held in Long Beach, California on November 4th, 2014.
- An abstract on the results of this project is posted online at the link: https://scisoc.confex.com/scisoc/2014am/webprogram/Paper86114.html
- A web article was prepared and will be posted on Rodale’s Institute web site in January 2015.
Experimental Design: After discussing the plan of work with Mr. Dan Hunsicker, the project was established using a randomized complete block design with four treatments and four replicates per treatment in 40 ft x 40 ft plots. The treatments were 1) standard practice-synthetic fertilizer and herbicides only (S), 2) compost +compost extract (CE), 3) compost (C), and 4) compost extract (E). The organic amendments were applied in addition to the standard practice.
Compost and Compost Extracts: Compost created at Rodale Institute was analyzed for chemical characteristics at Pennsylvania State University’s Agricultural Analytical Services Laboratory (AASL). One ton per acre was hand-applied onto plots that received C and CE on April 11, 2013. Compost extracts were prepared by mixing compost into water and bubbled for 24-hr before injection or spraying on the E and CE plots. On May 3rd, 2013, compost extract was injected, at time of planting at a rate of 187.1 liters per ha (20 gallons per acre) using the liquid fertilizer injector equipment, connected to the planter. The second and third applications of compost extract were one- and two-months after planting using a backpack sprayer on soils near corn plants. Samples of compost extracts were collected, stored in a refrigerator at 4 degrees centigrade and shipped overnight with ice packs to AASL for nutrient, pH, and EC analyses.
Soil Sampling: Soil samples were collected at 0-20 cm depth from all plots four times during the cropping season: 1) before compost application and corn planting, 2) before compost extract second application, 3) before compost extract third application, and 4) at harvest. Composite soil samples (15 cores per sample per plot) were homogenized, air-dried and sifted through 2-mm sieve. Soil samples were assessed for chemical characteristics at AASL.
Corn Harvesting: Ten linear feet in the center two rows of each plot were harvested. Whole plants were sampled from one row to determine stand count, whole plant fresh and dry weight and plant nutrients, and ears from the second row to asses yield. Whole plants were chipped and ground, and ears threshed to calculate yield per acre.
Statistical Analysis: Data were statistically analyzed using analysis of variance (ANOVA) (SAS Institute, 2012). Comparison of means was done using Fisher’s Least Significant Difference (LSD) test. Significant differences were accepted at α= 0.05.
Compost and compost extract chemical characteristics:
The compost was 41.0% solids, with a pH of 7.6 and electrical conductivity (EC) of 1.8 dS.m-1 (Table 1). The C/N ratio (12.1) of the compost was favorable for plant growth with a high nitrogen content. Compost extracts had pH levels ranging from 7.6 to 7.8 which was similar to the compost but had lower EC of 0.8 dS.m-1 and nutrient levels (Table 2). This is expected since the bubbling process used to produce the extract would increase microbial populations and nutrients would be concentrated in microbial bodies. Therefore, the extract can be applied to the foliar tissue without the risk of ‘burning’ the plant tissue due to high inorganic nutrient contents, and microbial populations can support plant health.
Soil physical and chemical properties:
Soil bulk density: Soil bulk density is a measure of a physical property, where higher values indicate less pore space and more compaction. Although not statistically different, bulk density in the soil treated with organic amendments was lower than in the conventional managed soil (1.39 versus 1.45 g per cubic cm). Since differences were measurable after only one year, additional years of high-quality organic amendments are likely to significantly decrease bulk density and improve soil health and root growth.
Soil chemical characteristics: Soil samples were collected multiple times throughout the study and analyzed for various chemical concentrations, but there were no significant interactions between the treatments and the date of sampling so the data was pooled across sampling date and only treatments were compared. Soil pH in C treatment (6.79) was statistically and significantly higher (P = 0.0285) than that in E, CE and S treatments (6.61, 6.59, and 6.57, respectively). Mean soil Mg concentration was significantly highest (P= 0.0410) in C treatment and lowest in E treatment. The higher values in soils that received compost can be attributed to the inherent compost values. Mean soil Zn concentration was highest (P=0.0157) in CE treatment (5.37 ppm) and lowest in S, E, and C (5.31, 4.78, and 4.71 ppm, respectively). Mean soil % O.M. was significantly (P= 0.0385) higher in CE treatment (3.41%) compared to the S, E and C treatments (3.07, 2.96, and 2.91 %, respectively). The higher values in soil % O.M. can be attributed to the synergetic effect of combined compost and compost extracts.
Whole corn plant dry weight and plant nutrient concentration:
There was no significant difference (P=0.05) in mean dry weight between treatments, but the trend increased in the following order: E, CE, C and S (20,382, 20,408, 20,974, and 21,237 kg per ha). Similarly, we did not find any significant difference in plant nutrients except for Zn which was significantly (P=0.0402) higher in the E treatment (19 ppm) compared to the S (18 ppm), and the C and CE treatments (16.25 ppm in each).
Corn grain yield:
Corn grain yield was slightly higher after compost [11,501 kg per ha (183.37 bu per acre)] than E, CE, and S treatments [11,441, 11,094, and 10,861 kg per ha (182.43, 176.89, and 173.16 bu per acre), respectively]. The harvest index (kernel per whole plant weight) followed the same pattern of corn grain yield and it was (0.57) in the E treatment followed by C and CE (0.55) and S treatment (0.51).
Within one year, the addition of organic amendments (such as compost) lowered soil bulk density and increased grain yield by 10 bu per acre which could translate into an increase in revenue by $165,000 for the 3000-acre farm. This additional income could justify equipment modifications to apply compost extract at planting and at V3-V6 stage in the coming years.
Education & Outreach Activities and Participation Summary
Project results were presented in a poster at the American Society of Agronomy Conference held in Long Beach, California on November 4th, 2014. The title of the poster is “Impact of Compost and Compost Extract as Amendments on Soil, Plant Biomass, and Corn Grain Yield.” The abstract has been published and available online at the following link https://scisoc.confex.com/scisoc/2014am/webprogram/Paper86114.html. A web article on these results has been written and will be posted on Rodale Institute’s website which receives average of 40,000 visitors and more than 80,000 page views per month.
Rodale Institute is a research, education, and outreach organization and project activities offered ample opportunities to train interns and technical support personnel on plant sampling, weighing, drying, and grinding; soil sampling and processing; and recording and inputting data. Research details were presented at the Rodale Institute Research Farm’s Annual Field Day on July 19, 2013 which had about 100 attendees. This project was a true partnership between Rodale and Mr. Hunsicker where both parties were involved in the design of the project and results may be used by Mr. Hunsicker to adjust his production system to include compost and compost extract.
Mr. Hunsicker is considering retrofitting his equipment to include compost and compost extract applications in the near future and testing composts produced at Rodale Institute.
Areas needing additional study
High-quality compost with a variety of physical and chemical properties may be produced at the Rodale Institute and utilized by Mr. Hunsicker and other partners in on-farm studies. Additional SARE funding will be requested to support future research projects to measure grain yield and quality and soil health parameters at these field sites.