Evaluating the use of forage radishes as a pasture improvement tool

View the project final report

• 2011 annual report
• 2012 annual report

Commodities

• Agronomic: general hay and forage crops, grass (misc. perennial), hay
• Vegetables: radishes (culinary)
• Animals: bovine
• Animal Products: dairy

Practices

• Animal Production: feed/forage, grazing management, grazing - rotational, pasture renovation, pasture fertility, stockpiled forages
• Crop Production: application rate management, no-till, nutrient cycling, organic fertilizers
• Education and Training: on-farm/ranch research, technical assistance
• Farm Business Management: budgets/cost and returns, whole farm planning
• Natural Resources/Environment: carbon sequestration, soil stabilization
• Production Systems: agroecosystems
• Soil Management: green manures, nutrient mineralization, organic matter, soil analysis, soil chemistry, soil microbiology, soil physics, soil quality/health
• Sustainable Communities: partnerships, sustainability measures

The objective of this study is to measure the impact of forage radishes on pasture productivity and soil health. The forage radish produces a nutritious, high yielding forage and large taproot capable of penetrating compact soil. The decomposition of the root in the spring creates an open conduit for water, air and the roots of other plants to penetrate deep into the soil profile. Seeding pastures with forage radishes may be a profitable remediation option for excessively wet, compact, or low quality pasture soils. The proposed field study will measure the effect of individual radish plants on infiltration rate, soil quality indicators and forage growth multiple times over the course of one year. The experiment will be replicated on three established pastures, each representing a different soil texture. Infiltration will be measured monthly on experimental units using the Cornell Sprinkler Infiltrometer. Standard soil quality indicators including soil moisture, organic matter, active carbon, and available nitrogen will be measured four times through the destructive sampling of equivalent experimental units. Forage samples will be collected three times in order to determine above ground biomass production and forage quality. Results will verify or refute a wide variety of anecdotal claims regarding the potential benefit of seeding pastures with radishes. I expect forage radishes may emerge as an essential tool to managing pastures for long term sustainability. They may be a simple, low cost tool capable improving farm productivity and soil health.

Objective One:
Quantify the effects of forage radish growth and decomposition on a variety of soil quality indicators
I expect soil organic matter, active carbon, moisture content, earthworm density and extractable nitrogen content to be higher in the radish treatments, particularly in samples collected within 5 cm of the decomposing root, than the control treatment during early and late spring. As the roots decompose, comminution and bioturbation by earthworms redistributes organic matter through the soil. The incorporation of plant residues in the surrounding soil as earthworm castings will increase soil quality. I will test my hypothesis by destructively sampling equivalent experimental units multiple times throughout year. Data will be analyzed by comparing plots with radishes to plots without radishes and using linear regression to establish the presence or absence of a spatial gradient around the decomposing root.

Objective Two:
Assess the impact of forage radish on forage production and quality.
I expect that the forage production and quality will be higher in the radish treatments than the control.
During the fall, the nutritious forage radish foliage will enhance forage quality and dry-matter production.
During the spring and summer, the decomposing root will release nutrients into the soil, reduce compaction, and create vertical holes which may facilitate air and water movement through the soil. Improvements in soil quality will also result in higher forage quality and yield (Drewry et al. 2008). I will test this by sampling above ground biomass during the fall, late spring, and late summer and performing a routine forage nutrient analysis. Data will be analyzed by comparing means between treatments.

Objective Three:
Monitor impacts of forage radish growth and decomposition on soil infiltration rates.
I expect no significant difference in infiltration rate among the radish and control treatments during the autumn and increased infiltration rate in radish treatment during the spring and summer. I will test this using Cornell Sprinkle Infiltrometer (van Es & Schindelbeck) to measure water infiltration once a month for one year, excluding months when the soil is snow covered. Data will be analyzed by comparing means between treatments.

Objective Four
Use experimental results to develop and distribute relevant and appropriate fact sheets for use by farmers and agricultural professionals describing how to utilize forage radishes in pastures and the possible advantages of doing so.