Pasture forage quality and yield response to irrigation, N fertilizer, and organic amendments

Pasture forage quality and yield response to irrigation, N fertilizer, and organic amendments

Summary

On the Forgues Family Organic Dairy Farm, near Alburg Springs, Vermont we began an experiment in May 2003 to study pasture forage yield and quality under management-intensive grazing. Treatments are: irrigation or nonirrigation, and eight levels of soil fertility treatments (0, PKlime, NPKlime, fish, fish/seaweed, crab shell, and two levels of dairy manure compost). This experiment is being used in conjunction with pasture walks to attract experienced and inexperienced graziers to learn about the research and aspects of management-intensive grazing. As a result of these activities, we project that experienced graziers will adopt at least two practices: pasture dry-matter estimating, feed planning, timing of N fertilization, use of organic soil amendments, or pasture irrigation; and inexperienced graziers will adopt management-intensive grazing.

Objectives/Performance Targets

Of the 60 experienced graziers and 30 inexperienced graziers invited to pasture walks during the 3 years of this project, 30 experienced graziers will adopt at least two of these new practices: a) pre- and post-grazing pasture dry matter estimating, b) feed planning, c) phenological timing of N fertilization, d)use of organic soil amendments, or e)pasture irrigation; 10 inexperienced graziers will begin using management-intensive grazing.

Accomplishments/Milestones

Forage yields (lb DM/acre) without irrigation ranged from an average of 4585 for control, PKlime, fish, fish/seaweed, and crab shell; to 6109 for NPKlime and 5 T/A compost, and 6906 for 10 T/A compost. Forage yields (lb DM/acre) with irrigation ranged from an average of 5436 for control, PKlime, fish, fish/seaweed, and crab shell; to 6337 for NPKlime, 6881 for 5 T/A compost, and 7010 for 10 T/A compost. Irrigation resulted in six grazings compared to five grazings for nonirrigated. Irrigation generally resulted in 0.5 ton/acre more total forage (worth at least $100/acre), compared to nonirrigated. Forage yields, quality factors, botanical composition, and soil nutrient levels are being analyzed statistically.
Milestone 1: 20 experienced graziers and 10 inexperienced graziers were personally invited to participate in two pasture walks held in May and August.
Milestone 2: 17 experienced graziers and three inexperienced graziers attended the pasture walks.
Milestone 3: nine experienced graziers and two inexperienced graziers requested assistance with using new management-intensive grazing
practices.
Milestone 4: seven experienced graziers are planning to begin using phenological timing of N fertilization, compost, and pasture irrigation next year; two inexperienced graziers will begin using management-intensive grazing next year.

Impacts and Contributions/Outcomes

First year preliminary results indicate that irrigation is desireable at the rate of 1/2 inch/week, even in a season receiving fairly well-distributed rainfall, as 2003 was at the research site. The extra grazing with its 0.5 T/A extra yield was worth at least $100/acre. This is calculated based on value of hay; high-quality pasture forage such as this is worth more than hay. It was also clear that applying organic nitrogen fertilizer or compost was beneficial in terms of forage yield and quality. Compost application had the most beneficial effect on yield and legume content of the sward. Another benefit was obtained by clipping after each grazing; this practice clearly maintained the sward at a high level of quality for subsequent grazings, it will be used on the entire Forgues Farm pasture next year.

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