Deep soil nitrogen: A resource for sustainability in the mid-Atlantic using early cover crops

Deep soil nitrogen: A resource for sustainability in the mid-Atlantic using early cover crops

Summary

We had exceptional interest and engagement among farmers in 2015. We focused on two farms in the Eastern Shore region of Maryland and six in the Piedmont region of Maryland and Pennsylvania. During August-September, we collaborated with seven farmers to take transects of deep soil cores in order to assess how much N remained after growing corn. In the 2015 on-farm experiments we took more soil cores per plot in order to reduce within-plot variability, but this necessitated sampling fewer farms than in 2014.  In 2015 we collaborated with eight farmers to conduct experiments on their farms. We set-up cover crop experiments that included four basic treatments:

1. Forage radish,
2. Winter cereal (rye, triticale, or oats),
3. Mixed cover crops (radish, winter cereal, usually clover), and
4. No cover control, each treatment replicated four times.

On most of these farms, the plots were planted by the farmers and were large enough to allow farmer combine harvest next year. In November-December, we took four to five 210 cm deep soil cores and collected biomass from four to five 0.25m² quadrats within each plot at three of the farms, and we took cover crop biomass samples from each plot at four additional farms. Additionally, in 2015 we have three farms with interseeded cover crop trials, three farms with irrigated cover crop trials, two farms experimenting with early vs. late planted cover crops, and two farms evaluating 10 lb/acre of starter-N for cover crops. Furthermore, the SARE graduate student grant, “On-farm and isotopic evaluation of deep soil nitrogen capture and cycling by cover crop mixtures” allowed us to expand the N tracer work; we set-up 172 plots to investigate how cover crops capture residual N and recycle it for subsequent corn. We have discussed our work through numerous presentations and publications, listed in the Impacts and Contributions/Outcomes section below.

Objectives/Performance Targets

250 farmers plant 25,000 acres early radish/rye covercrops reducing N leaching by 2,000,000 lbs; 100 of them also reduce N application by 50 lbs. on 10,000 acres, saving $0.5 million annually. 20 advisers recommend early covercrops and 2 state Agriculture Departments include them in their N load reduction programs.

Accomplishments/Milestones

-1000 dairy, 250 grain and 100 vegetable farmers managing 250,000 acres will learn through newsletters, field days, farm newspaper stories and extension meetings about early cover crops to reduce N fertilizer needs and prevent water pollution. 

Three Keynote talks were made at The Conservation Cropping Systems Initiative (approximately 360 attendees total), presentations were given at the joint Soil Science Society of America/American Society of Agronomy annual international meetings, at the Commodity Classic Field Day (approximately 50 attendees), at a Soil Health Field Workshop for Agricultural Service Providers (approximately 20 attendees), at the PA Dairy Summit (approximately 60 attendees), and at the Crop Day Meeting (approximately 80 attendees).

We were able to reach out to an audience of thousands via a number of online videos focusing on our deep rooting cover crop theme. These videos were produced by third parties (NRCS, Cover Crop Solutions and others) and included two parts of  “The Science of Soil Health: Going Deeper” (nearly 6,000 views) and “On Farm Interview Series: Dr. Ray Weil’s Deep Nitrogen Study” (1,350 views). In addition, the Land Stewardship Project  published a podcast: “A soil scientist compares Indiana’s ‘bottom up’ approach to advancing soil health to Maryland’s ‘top down’ system.” in their “Ear to the Ground” series.

-In the first year, 20 farmers (10 dairy and 10 grain or vegetable each year) will collaborate by permitting us access to designated areas on their farms for us to assess deep N under their fields. 

Deep soil cores were taken on 7 farms between 8/26/15 and 9/25/15. Time and labor restricted us from sampling more farms, because soil cores were taken using hand-driven Veihmeyer probes.

-In each of three years, 10 farmers will collaborate by planting replicated strips with and without cover crop (2 trts) on their farms so we to access the N uptake and/or soil profile N depletion by one selected species of early planted, deep-rooted, non-immobilizing covercrops.

-In each of two years, 5 farmers will collaborate by planting replicated strips with 4 covercrop treatments to evaluate N uptake by 2 species and a multi-species cocktail of early planted, deep-rooted, non-immobilizing covercrops. 

In 2015, 8 farms set-up cover crop experiments with 4 treatments—1. Radish, 2. Winter cereal, 3. 2 or more species mix, 4. No cover crop control. In addition, 3 sites had interseeded cover crop trials, 3 sites had irrigated cover crop trials, 2 sites had early vs. late planted cover crop trials, and 2 sites had trials evaluating 10 lb/acre of starter-N for cover crops.

-In each of two years, 2-3 farmers will help us design and conduct spring N response trials superimposed on late summer cover crop treatments. 

Four of the farmers with 2014 cover crop experiments planted spring N response trials on cover crop treatments. We harvested corn from 3 of these farms; on the fourth farm the farmer panted the corn in a way that harvest equipment was unable to take accurate yield measurements.

-8 of the collaborating farmers host and speak at field days on their farms. 

One participating farmer hosted a field day for agricultural service providers on September 16, 2015.

-200 dairy and 50 grain or vegetable farmers will plant 25,000 acres of early covercrops reducing N leaching by 2,000,000 lb. (avg. 80 lb N/acre reduction)

-100 of these farmers will also reduce fertilizer N use by 50 lb on 10,000 acres, saving 500,000 lbs N or $1.0 million (cost of N = $0.70 to $9.00/lb; avg. $1.00/lb N, includes some high priced N for organic and vegetable farms).

-20 crop advisers will make early covercrops part of their recommendations.

-2 state Departments of Agriculture will include early covercrops in their N load reduction programs.

The Maryland Department Agriculture cover crops program included extra incentives for early planting, and for the first time allowed cover crop mixtures that included legumes.

Impacts and Contributions/Outcomes

Farmer interest concerning deep-soil N content and cover crop systems was outstanding; we had more farmers volunteer to participate in the study than we could accommodate. We focused on eight farms in the Piedmont regions of Pennsylvania and the Piedmont and Coastal Plan regions of Maryland. We took deep soil cores on seven of these farms during August-September. Because farmers and extension personnel expressed surprise and doubt concerning high N levels found in August-September 2014 (100-500 kg/ha mineral N), we wanted to investigate possible exaggerated N levels that may have resulted from the position of the soil cores in regards to the placement of previous side-dressed fertilizer. Therefore, we took soil cores in the previous corn row, 15” from the corn row (halfway between rows), and 7.5” from the corn row. We set-up cover crop experiments that included four treatments on eight farms—1. Forage radish, 2. Winter cereal (rye, triticale, or oats), 3. Mixed cover crops (radish, winter cereal, usually clover), and 4. No cover control, each treatment replicated four times. Farmers chose what species to plant and planted the plots under the guidance of extension collaborators. In November-December, 2015, we took four to five 210 cm deep soil cores and collected biomass on four to five 0.25m² quadrats within each plot at experiments in Walkersville, MD, Vienna, MD, and Gordonville, PA. In addition, we took cover crop biomass samples from the experimental plots in Rock Hall, MD, Greencastle, PA, Holtwood, PA, Spruce Creek, PA, and plan to take samples on plots at Clarksville, MD this week. Due to high variability in the 2014 data, we took four to five deep soil cores per plot in 2015 rather than the two cores per plot we took in 2014. Soil cores are taken using hand-driven Veihmeyer probes, which is effective but slow, therefore limiting the number of farms we could sample. We have received questions from agricultural service providers and farmers regarding optimal cover crop planting methods and establishment techniques that encourage fall cover crop growth. Therefore, in 2015 we have three sites with interseeded cover crop trials, three sites with irrigated cover crop trials, two sites experimenting with early vs. late planted cover crops, and two sites evaluating 10 lb/acre of starter-N for cover crops. In addition, with support from the SARE graduate student grant “On-farm and isotopic evaluation of deep soil nitrogen capture and cycling by cover crop mixtures”, we able to greatly expand the work using 15-N isotope to investigate the N uptake of cover crop species. In August 2015, we set-up 172 plots to investigate if deep-rooted, early planted cover crops can capture residual N and recycle it for subsequent corn. We buried 15-N and bromide as nitrate tracers at 60, 120, and 180 cm depths to simulate N that remained after corn uptake ceased, and planted 1) forage radish (Raphanus sativus), 2) rye (Secale cereale), 3) forage radish + rye, and 4) forage radish + rye + Crimson clover (Trifolium incarnatum), on Sept 3 or Oct 8, on a sandy soil and a clayey soil site. 

In 2015, we shared results of this study through the following events and publications:

Weil, R. 2015. The science of soil health: Going deeper, In B. Koots, (ed.) Unlock the Secrets in the Soil. USDA/NRCS. https://www.youtube.com/watch?v=XzfFFNG5mnQ

Weil, R. 2015. The science of soil health: Going Deeper, part 2, In B. Koots, (ed.) Unlock the Secrets in the Soil. USDA/NRCS.https://www.youtube.com/watch?v=Qo6zvBBROL0

Weil, R. 2015. Dr. Ray Weil’s deep nitrogen study. Fresh from the Field: On Farm Interview Series. Cover Crop Solutions. https://www.youtube.com/watch?v=X21bge_yVUY

DeVore, B. 2015. King of the cover crops: An Indiana initiative has made the state a national leader in getting continuous living cover established on crop acres. Can it change the way farmers view soil? The Land Stewardship Letter 33(4):24-27. Features Ray Weil’s week-long visit to Indiana’s Conservation Cropping Initiative.

Weil, R.2015. A soil scientist compares Indiana’s ‘bottom up’ approach to advancing soil health to Maryland’s ‘top down’ system. Ear to the Ground, Episode 174, Land Stewardship Project, http://landstewardshipproject.org/posts/podcast/787

Hirsh, Sarah M. and Raymond Weil. 2015. Isotopic Evaluation of Deep Soil Nitrogen Uptake by Cover Crop Systems. Presented to the joint Soil Science Society of America/American Society of Agronomy annual international meetings, Minneappolis, MN. 15-18 Nov. 2015.

Weil, Ray. 2015. Soil Health Systems. Keynote talk. The Conservation Cropping Systems Initiative and Purdue University. Covington, IN. 18 Aug. 2015. 180 farmers and agric. professionals in attendance.

Weil, Ray. 2015. Lessons Learned from Chesapeake Bay- Soil Organic Matter Management for Nutrient Cycling and Agricultural Sustainability. Keynote talk. The Conservation Cropping Systems Initiative, Moody Farms. Fremont, IN. 19 Aug. 2015. 100 farmers and agric. professionals in attendance.

Weil, Ray. 2015. Lessons Learned from Chesapeake Bay- Soil Organic Matter Management for Nutrient Cycling and Agricultural Sustainability. Keynote talk. The Conservation Cropping Systems Initiative and Bartholomew County Soil and Water Conservation District. Columbus, IN. 20 Aug. 2015. 80 farmers and agric. professionals in attendance.

Hirsh, Sarah and Ray Weil. 2015.  “Planting Early Cover Crops to Capture and Recycle Deep Soil Nitrogen: an Untapped Resource for Profitability and Environmental Stewardship”. Presentation at Commodity Classic Field Day. Centreville, Md. 23 July 2015. 50 farmers and agric. professionals in attendance.

Hirsh, Sarah M. “Planting Early Cover Crops to Capture and Recycle Deep Soil Nitrogen: an Untapped Resource for Profitability and Environmental Stewardship”. Presentation at Soil Health Field Workshop for Agricultural Service Providers.  Leonardtown, MD. 16 September 2015. 20 agric. service providers in attendance.

Hirsh, S., R. Weil. Fall 2015. It’s August—are your cover crops growing yet? University of Maryland Extension Ag Newsletter. pp. 5-6.

Weil, Ray. 2015. Invited paper: The Soil Health Revolution in American Agriculture and What It’s Success Could Mean for the Planet. 9th Annual Meeting of Pesticides and the Chesapeake Bay Watershed Project. Maryland Pesticide Network and The Johns Hopkins Center for a Livable Future. Pearlstone Conference Center. Reisterstown, MD. 8 Oct. 2015. http://www.mdpestnet.org/wp-content/uploads/2015/11/Dr-Ray-Weil-presentation-10.28.2015.pdf

Graybill, Jeffrey S. December 2015. Is excessive growth effecting the winter survival of small grains? Penn State Field Crops Newsletter. http://extension.psu.edu/plants/crops/news/2015/12/is-excessive-growth-effecting-the-winter-survival-of-small-grains

Graybill, Jeffrey S. “Successful integration of manure cover crops and no-till”. Presentation at PA Dairy Summit. Lancaster, PA. 4 February 2015. 57 in attendance.

Patches, Kelly. “Cover crops”. Crops Day Meeting. 28 January 2015. 80 in attendance.

Collaborators: