Performance of Various Forage Combinations Under Thinned Pine Canopies in North Florida

Performance of Various Forage Combinations Under Thinned Pine Canopies in North Florida

Summary

Suitability and performance of warm/cool season forage combinations is tested under thinned 18-year-old loblolly pine canopies in North Florida. After tree stand thinning, prescribed burning, and harrowing, Argentine bahiagrass was established in July, and winter forages in November 2003. Forage yield and quality is evaluated monthly in relation to intercepted solar radiation. Tree growth and crown characteristics are measured on annual basis and will be used to assess the influence of tree canopy conditions on forage production. Forage and tree nutrition status is monitored after fertilization treatments.

Objectives/Performance Targets

Objective 1: Silvopasture Establishment after Tree Stand Thinning

Objective 2: Forage Yield and Quality in Silvopasture Compared to Open Pasture

Objective 3: Tree Growth in Silvopasture Compared to Pine Plantation

Accomplishments/Milestones

Objective 1: Silvopasture Establishment after Tree Stand Thinning

Status: Accomplished
Procedures:
Tinned tracts were prescribed burned in April 2003. Area was further cleared by removal of remaining logging debris from the experimental plots. Hardwood trees were cut down and stumps treated with herbicide (Garlon 3A) to prevent sprouting. Weeds were controlled by herbicide application (Roundup WeatherMax) in June 2003. The double-row and heavily thinned areas were harrowed prior to Argentine bahiagrass seeding in July 2003. Winter forages were overseeded in November 2003. Winter forages received 50 lbs N per acre in January 2004, and 50 lbs N plus 83 lbs K in March 2004. Summer forage plots will receive 100 lbs N and 83 lbs K per acre in April 2004. Forage fertilization was based on soil testing results. Two circular wire exclusion cages 0.90 sq meter in size were placed on each forage plot to prevent wildlife browsing from forage sampling spots.

Objective 2: Forage Yield and Quality in Silvopasture Compared to Open Pasture
Status: Ongoing
Procedures:
Yield and quality of the following forage combinations are currently tested under two pine canopy conditions in comparison to open pasture:
Argentine bahiagrass alone
Argentine bahiagrass plus Jumbo ryegrass
Argentine bahiagrass plus Jumbo ryegrass plus Dixie crimson clover
Argentine bahiagrass plus Jumbo ryegrass plus Dixie crimson clover plus Cherokee red clover
Winter forage evaluation started in February 2004. Summer forage evaluation will begin after bahiagrass resumes growth following the 2003/04 dormant season. Forages are harvested every 4 weeks by clipping within exclusion cages. The following parameters are measured: (i) herbage mass (dry matter in forage clippings); (ii) botanical composition; (iii) nutritive value (crude protein and in vitro organic matter digestibility).

Forage intercepted photosynthetically active radiation (PAR) is measured before forage harvest within exclusion cages to determine influence of tree canopy shading on forage production.

Objective 3: Tree Growth in Silvopasture Compared to Pine Plantation
Status: Ongoing
Procedures:
Tree heights, diameters at breast height (DBH), and crown widths in two perpendicular directions were measured in December 2003. This data will allow tree growth and crown characteristics comparisons between the silvopastures and conventional pine plantations.

Tree foliage was sampled in February 2004 and will be sampled again in early 2005. Foliage will be analyzed for N, P, K to determine the impact of silvopasture fertilization on tree nutrition.

Impacts and Contributions/Outcomes

To date two in-service trainings (December 2003 and March 2004) for county agents were conducted each featuring a field trip to the silvopasture experimental site. The prelimnary results of this experiment were presented in the field to 12 Florida extension county agents, 4 Florida Division of Forestry foresters, and 2 Florida landowners attending agroforestry in-service trainings at the UF/IFAS North Florida Research and Education Center near Quincy, FL. A poster describing preliminary results of this experiment has been accepted for presentation at the 1st World Agroforestry Congress in Orlando, FL in June 2004.

Collaborators: