NITROGEN LOSSES FROM AGRICULTURE: COMPARING ORGANIC AND CONVENTIONAL FARMING

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1000965
• Project Start Date: Oct 1, 2013
• Project End Date: Sep 30, 2016
• Program Code: [(N/A)]- (N/A)

Recipient Organization
CORNELL UNIVERSITY
(N/A)
ITHACA,NY 14853

Performing Department
Ecology & Evolutionary Biology

Non Technical Summary
To evaluate the nitrogen pollution from organic farming compared to conventional farming in New York State.

Animal Health Component

50%

Research Effort Categories

Basic

50%

Applied

50%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
112	0399	1070	50%
112	2410	1070	25%
133	2410	1070	25%

Knowledge Area
133 - Pollution Prevention and Mitigation; 112 - Watershed Protection and Management;

Subject Of Investigation
0399 - Watersheds and river basins, general; 2410 - Cross-commodity research--multiple crops;

Field Of Science
1070 - Ecology;

Keywords

nitrogen pollution

organic agriculture

Goals / Objectives
Our goal is to test the hypothesis that organic agriculture in New York produces less nitrogen pollution per unit of crop harvest than does conventional agriculture. The immediate objective is to estimate the loss of nitrate to below the rooting zone on organic farms in New York State that are growing grain crops such as corn and wheat. We will express this loss in three ways: as a rate per area of farmland, as a percentage of the nitrogen inputs to the farming system, and relative to the crop yields from the farms. We will compare our data with similar information previously collected in New York for conventional farming, and with data on nitrate losses from organic agriculture reported elsewhere. Such information on nitrate loss can be used as input to a variety of models which then estimate the extent of downstream nitrogen pollution in aquatic ecosystems and the emissions of nitrous oxide gas.

Project Methods
We will select representative organic farming systems in central New York, focusing on grains such as corn and wheat, with advice and assistance from Krys Cail of the Northeast Organic Farmers Association and Dr. Laurie Drinkwater of Cornell's Department of Horticulture. We will characterize nitrate losses from these systems by periodically sampling water from the sub-root zone in the soil, using low-tension lysimeters, following the methodology of our colleagues in France (G. Billen and J. Garnier, unpublished data) and that used for measurements in conventional systems for the best cross-systems comparisons. The nitrate flux will be calculated by multiplying the mean monthly nitrate concentrations by the water export from the surface soil for that month; we will use the ReNuMa model and rainfall and temperature data to estimate the water export. We will interview farmers to determine the amount of manure input to these systems, and the rotation history of nitrogen fixing crops such as alfalfa and soybean, and then estimate the nitrogen inputs from the manure and the nitrogen fixing crops, using the Net Anthropogenic Nitrogen Inputs (NANI) model (Hong et al. 2011, 2013; Howarth et al. 2012). We will estimate nitrogen inputs from atmospheric deposition using the CMAQ model of the US EPA. We can then estimate nitrate losses as a function of the total nitrogen inputs. We will also report nitrate losses per area of farmland and as a function of the crop harvest (as reported by the farmers). And we can estimate the surplus nitrogen available for leaching (the difference between nitrogen inputs and nitrogen harvested in crops), following the procedure of Billen et al. (2012). We will compare estimated and measured nitrate losses with those from conventional agricultural systems in central New York, using existing data provided by Jeff Melkonian of Cornell's Department of Crop and Soil Sciences. Melkonian as well as Gilles Billen and Josette Garnier of the Univ. of Paris will advise on the field lysimeter measurements and on overall data interpretation. Howarth and Marino spent the spring of 2009 on sabbatical leave in Paris in the lab of Billen and Garnier and have a close working relationship with them.

Progress 10/01/13 to 09/30/16

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?Through presentations of our findings at regional and national meetings. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? At regional scales of the US, we have found that nitrogen use efficiency of crops shows an increasing, asymptotic or linear relationship to the contribution of nitrogen fixation by crops (soybeans, alfalfa) expressed as a proportion of total nitrogen inputs to regional agriculture. It also shows a strong positive relationship to the proportion of manure nitrogen. In contrast, synthetic fertilizer nitrogen shows a negative response in most regions of the US. Increased nitrogen use efficiency (NUE) implies that nitrogen pollution is lower in regions that rely more on nitrogen fixation or manure N, such as those with organic farms. Recent USDA statistics now indicate that that acreage of organic crops has grown exponentially between 1997 and 2012 in the Northeastern and Western states of the US, but still represent only a small percentage of the total crop acreage. Organic acreage in the Midwest and Southern states have seen more modest increases, and while the acreage is large in these regions, it is small expressed as a percentage of the total acreage compared to that in the Northeast In New York, acreage of organic legume crops (soybeans and other beans) have increased 4-fold between 1997 and 2011. Organic livestock inventories in New York and the Northeast also represent a significantly higher proportion of total livestock than in most other regions. . For the US agricultural census year 2007, we examined county-level data, and found statistically significant relationships between the number of organic farms or the acreage of organic cropland and county-level nitrogen use efficiency for New York counties outside of New York boroughs and Long Island. Similarly, we have found statistically significant negative relationships between organic agriculture and net anthropogenic nitrogen inputs for New York counties. This has provided a foundation for our future research along these lines.

Publications

• Type: Journal Articles Status: Other Year Published: 2017 Citation: Nitrogen use efficiency, crop production and diversity: Regional variation in the United States, 1987-2012. In preparation. D.P Swaney, R.W. Howarth and B. Hong.
• Type: Conference Papers and Presentations Status: Other Year Published: 2016 Citation: The Role of the Mohawk in Hudson River Nutrient Dynamics. Swaney, D.P., B. Hong, and R. W. Howarth. 2016 Hudson River Symposium: Watershed Influences in a Changed World, Hudson River Environmental Society, May 4th, 2016, SUNY New Paltz, New Paltz, NY.
• Type: Conference Papers and Presentations Status: Other Year Published: 2015 Citation: Nutrient accounting in coastal waters and watersheds: linkages and applications. Swaney, D.P. 23nd Biennial Conference of the Coastal and Estuarine Research Federation, November 8-12, 2015. Portland, OR
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: A toolbox for estimating regional nitrogen and phosphorus inputs to US watersheds. B. Hong, Swaney, D.P, and R. W. Howarth. 23nd Biennial Conference of the Coastal and Estuarine Research Federation, November 8-12, 2015. Portland, OR.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Trends in Anthropogenic N Inputs to the Hudson River Watershed. Swaney, D.P., B. Hong, and R. W. Howarth. 2014 Hudson River Symposium: Watershed Influences in a Changed World, Hudson River Environmental Society, May 7th, 2014, SUNY New Paltz, New Paltz, NY.

Progress 10/01/14 to 09/30/15

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?We will continue to analyze county-level to regional-level patterns of nitrogen use efficiency, and use this as a surrogate to estimate surplus nitrogen and nitrogen pollution. We currently have a manuscript discussing regional patterns of nitrogen use efficiency in preparation for publication in the peer-reviewed literature.

Impacts
What was accomplished under these goals? We have found that nitrogen use efficiency of crops shows an increasing, asymptotic or linear relationship to the contribution of nitrogen fixation by crops (soybeans, alfalfa) expressed as a proportion of total nitrogen inputs to regional agriculture. It also shows a strong positive relationship to the proportion of manure nitrogen. In contrast, synthetic fertilizer nitrogen shows a negative response in most regions of the US. Increased nitrogen use efficiency implies that nitrogen pollution is lower in regions that rely more on nitrogen fixation or manure N, such as those with organic farms. Examining recent USDA statistics, we have found that while acreage of organic crops represents only a small percentage of the total crop acreage in the northeastern US, it has increased nearly 10-fold since the 1990s, and is significantly higher than the proportion of organic agriculture in other regions such as the Midwestern and Southeastern US. Organic livestock inventories in New York and the Northeast also represent a significantly higher proportion of total livestock than in most other regions.

Publications

Progress 10/01/13 to 09/30/14

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? We will continue to follow our start of county-level analysis of nitrogen use efficiency, and use this as a surrogate to estimate surplus nitrogen and nitrogen pollution. During year 2, we will prepare a manuscript for publication in the peer-reviewed literature on this work.

Impacts
What was accomplished under these goals? We have started by focusing on the relative contribution of nitrogen fixation by crops (soybeans, alfalfa) as nitrogen inputs to agriculture in New York. We broadened the analysis to all of the northeastern US, since this was relatively easy to do and increases our statistical power, when we look at county-level information. Our preliminary results to date (after one year) show that nitrogen use efficiency is much higher when nitrogen fixation is a larger portion of total inputs. This implies that nitrogen pollution is less from farming operations that rely more on nitrogen fixation, such as organic farmers.

Publications