Rodale Institute Vegetable Systems Trial

VEGETABLE SYSTEMS TRIAL RESEARCHING THE LINKS FROM SOIL HEALTH TO VEGETABLE NUTRIENT DENSITY TO HUMAN HEALTH

The Vegetable Systems Trial is a side-by-side comparison of conventional and organic methods for growing vegetables.

Located at Rodale Institute’s main campus near Kutztown, Pennsylvania, the Vegetable Systems Trial (VST) was launched in 2016 with a global scope.

This unique long-term study explores a novel approach to link soil health to crop nutrient density to human health, by comparing side-by-side the impact of cropping systems and management practices on changes in soil health indicators and nutritional quality of vegetables, all within the same set of environmental conditions.

WHY DOES IT MATTER? The nutrient density of fruits and vegetables grown in the U.S. has declined in the past 50 to 70 years. That means many people today are struggling with “hidden hunger”—they’re getting enough calories but not the vital nutrients necessary for health.

While many agricultural management practices aim to promote healthy soil, not all lead to improved soil health. We need to know: a) Which cropping systems and management practices contribute to the development of healthier soils? b) Do these healthier soils yield nutrient-dense vegetables? c) C an they contribute to improving human health?

The VST is aimed at answering these important questions.

THE STUDY The VST aims to provide scientific information to vegetable growers, professional educators, consumers, and the public at large to make better choices in managing soil health, protecting the environment, and producing and consuming nutrient-dense crops.

Vegetables including potatoes, sweet corn, green beans, winter squash, and lettuce are selected and grown side-by-side in organic and conventional cropping systems under intensive and reduced tillage practices.

These crops represent either a tuber, fruit, or leaf and are considered economically important to Pennsylvania’s agricultural sector.

The VST sits on 2.62 acres and includes cropping blocks and buffers. Each crop is grown in a 20-by-80-foot plot every year in a crop rotation that spans three years.

Data collected will result in information that addresses: • Differences in nutrient density of vegetables • Differences in soil health over time • Drought resilience • Resilience to insects, diseases, and weed pressure • Profitability

CROPPING SYSTEMS & MANAGEMENT PRACTICES CROPPING SYSTEMS Organic Fertility is supplied through leguminous hairy vetch and cereal rye cover crops, complemented by applications of organic fertilizers and compost in the case of potatoes.

Only OMRI-certified pesticides are used for pest control.

Weeds are controlled by shallow cultivation using a Treffler cultivator before germination of crops in plots with intensive tillage practices, hill-side cultivation between raised beds covered with plastic mulch, or rollcrimping in reduced tillage with occasional high residue.

Conventional A cereal rye cover crop is used, but unlike in the organic system, it is burnt down with the herbicide glyphosate prior to planting the vegetable crops. Soil amendments rely on synthetic nitrogen and potassium sources for fertility. Because the soil in VST has excessive phosphorus levels, this amendment is not included in the fertility program. Pests and pathogens are controlled using synthetic fungicides and insecticides.

PRELIMINARY RESULTS In the six years after the establishment of the Vegetable Systems Trial, results show: • Carbon levels have increased in the top 4-inch soil layer in the organic cropping system coupled with reduced tillage management practice and declined in the conventional system with reduced tillage.

• Soil organic matter increased by 1% which is equivalent to 11,600 pounds in an acre slice soil (6.7inch deep) or 14.3 tons per hectare of carbon.

Mirroring the most common vegetable production strategies throughout the United States, the VST has two unique cropping systems: ORGANIC and CONVENTIONAL. Within each system, two tillage practices are employed: intensive tillage and reduced tillage.

MANAGEMENT PRACTICES Intensive Tillage This practice represents the vegetable grower’s standard practice, where the soil is intensively tilled using the moldboard plow, followed by disking and preparing raised beds covered with plastic mulch. Crops are transplanted using the water wheel transplanter attached to a tractor.

Each 20-by-80-foot plot contains three raised beds.

Reduced Tillage Reduced tillage practice, a comparison to intensive tillage, is introduced to enhance soil health over time.

In this practice, a rotational tillage is employed. The soil is chisel plowed and then disked to seed cover crops in the fall. In spring, the cover crops in the organic system are roll-crimped to form a biological mulch to control weeds, whereas in the conventional system the cover crop is burnt down with herbicide. This practice uses either a no-till transplanter to transplant vegetable crops or the Monosem planter to seed snap beans directly into mulch.

• This 1% increase will result in holding 20,000 gallons of water per acre (187,000 liters/hectare).

• A 30% increase in labile organic soil carbon (POX-C), from 600 to 900 mg/kg.

This is a sign of building resilience towards changes in climate or other stressors.

• Over time, the implementation of intensive tillage depleted soil carbon and increased soil bulk density.

• Nutrient density in vegetables varied with time. We expect to link soil health to vegetable nutrient density as the Vegetable Systems Trial studies continue.

DR. GLADIS ZINATI Director, Vegetable Systems Trial

Dr. Gladis Zinati, director of the Vegetable Systems Trial and soil scientist, evaluates the impact of cropping systems and management practices on nutrient cycling, carbon sequestration, vegetable nutrient density, and plant resistance to pests.

She conducts research on no-till practices, fertilizers, cover crops, compost formulations, and biological tools to improve pest management. She has more than 30 years’ experience and holds undergraduate degrees in general agriculture and agriculture engineering; an M.S. in horticulture from the American University of Beirut; and a Ph.D. in soil fertility from Michigan State University.

Before joining Rodale Institute in 2012, Dr. Zinati worked on projects evaluating management practices that optimize crop yields and reduce degradation of water quality at the University of Florida and Rutgers University.

To contact Dr. Zinati: Gladis.Zinati@RodaleInstitute.org

OUR MISSION To advance groundbreaking research and best-in-class education that enables farms and farmers to transition to regenerative organic agricultural practices, thereby improving the health of the world’s soil and securing the global food supply.

For more about the Vegetable Systems Trial, visit RODALEINSTITUTE.ORG/VST This material is based upon work supported by the following funders. The opinions expressed in this publication are those of the author(s) and do not necessarily reflect the views of the funders.

• G rantham Foundation for the Protection of the Environment • JHC Foundation • Johnny’s Selected Seeds • Orange County Community Foundation • PA Department of Agriculture • PA Vegetable Marketing & Research Program • Paloma Blanca Foundation • The GIANT Company • Wyncote Foundation

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