How the Transition to Organic Grain Effects Biological Indicators of Soil Health

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Commodities

• Agronomic: corn, hay, oats, soybeans, wheat

Practices

• Crop Production: conservation tillage, cover crops, crop rotation, no-till, organic fertilizers
• Education and Training: farmer to farmer
• Natural Resources/Environment: biodiversity, carbon sequestration, indicators
• Production Systems: transitioning to organic
• Soil Management: soil microbiology, soil quality/health
• Sustainable Communities: sustainability measures

The three-year transition period to organic certification is a major roadblock to Maryland farmers interested in organic grain production. Transitioning farmers must cease using their customary synthetic products and learn new organic techniques (often requiring new equipment) while receiving only conventional prices. In Maryland, most conventional farmers already use cover crops and practice no-till agriculture in a corn-wheat-double soybean rotation. Thus, we need transition strategies that will not degrade soil health by introducing intensive tillage but will provide profitability during the transition period. Currently, we are comparing four strategies using replicated experiments at four locations, two on commercial farm fields undergoing transition, and two on university research stations. The four strategies vary in levels of soil disturbance, cover crop intensity, and input costs and are being evaluated for their practicality, profitability, and soil health impacts. Typically, soil health assessments rely mainly on physical and chemical indicators to the neglect of soil biology. NE-SARE funding would allow us to add important microbial indicators that are of particular interest to organic farmers. We propose to study the microbial community structure, diversity, and functionality within the four systems on multiple temporal and spatial extents. We will perform metagenomic analysis by using DNA extraction, amplification and quantification techniques for bacteria and fungi. By understanding how management affects the biotic components of soil ecosystem, we anticipate to be able to help farmers design more efficient agricultural systems for organic transitions.

This project is part of a broader research program titled "Transitioning to organic grain production: strategies to increase viability and ecosystem services while reducing risks and obstacles," which is sponsored by the National Institute of Food and Agriculture (NIFA). The ultimate aim of the research project is to help boost the competitiveness of transitional organic grain crop producers by identifying system parameters that positively impact soil quality, crop yields,  practicality and profitability. Microbiological indicators of soil health in the four transition systems will be the focus of this NE-SARE project. The following are the specific objectives:

1. Examine the effects of four organic transitional strategies on the composition and diversity of microbial communities.

The four systems will be contrasted in terms of the types of prokaryotic communities (bacteria) and fungi, as well as their relative abundance and diversity. We hypothesize that the microbial community structure and diversity will differ among the systems and minimal tillage systems with higher biomass diverse cover crops will favor more microbial diversity.

2. Study the effect of the transition strategies on potential microbial functionality. 

We’ll study the relative abundances of enzyme encoding genes involved in certain functions and link that to potential microbial functionality (e.g. C degradation, N cycling) in the four systems by using databases such as Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway database and ITS gene data.

3. Investigate the relationship between microbes and soil physical-chemical properties.

We will correlate the microbial diversity and individual microbial taxa with the soil physico-chemical properties. 

In the larger study, the results from this study, as well as other bioindicators like earthworm, slug, and arthropod populations and carbon and nitrogen lability will be assessed. A soil health index will be developed using all of the bioindicators, in addition to chemical and physical characteristics of the soil.