Strategies for Increasing Rhizoma Peanut Contribution to Productivity and Ecosystem Services of Low-Input Pasture Systems

Strategies for Increasing Rhizoma Peanut Contribution to Productivity and Ecosystem Services of Low-Input Pasture Systems

Summary

Experiments were established to evaluate technologies for incorporation of rhizoma peanut (RP) into low-input, grass-based pasture systems in the SE USA. Based on 2011 data, Florigraze and Ecoturf RP cultivars have the greatest potential for incorporation into bahiagrass using strip planting methodology. Defoliation management of RP did not affect establishment rate as much as the RP genotype used. This suggests that strip-planting may be a viable option for producers to improve pasture productivity and sustainability. Further research will be conducted in 2012 and 2013 to evaluate soil and plant responses of RP- and bermudagrass-based systems to grazing management practices.

Objectives/Performance Targets

1. To quantify the effects of growth habit of rhizoma peanut (RP) and defoliation management during the establishment year on ground cover and rate of spread of RP cultivars following strip planting into bahiagrass pasture
2. To measure the effect of grazing intensity and frequency on forage accumulation, persistence, and nutritive value of four RP cultivars differing in plant growth habit
3. To quantify the effect on soil organic carbon and nitrogen accumulation of forage systems based on RP or nitrogen-fertilized bermudagrass

Accomplishments/Milestones

In March 2011, an establishment study was planted at the UF Beef Research Unit (Gainesville, FL) to evaluate the impact of RP growth habit and sward management on rate of establishment using a strip-planting approach in bahiagrass pastures. Total sprout emergence (# sprouts/m2) was recorded until 12 weeks after planting. In June, defoliation treatments (grazing or clipping every 4 weeks) were implemented. Ground cover and frequency of RP occurrence were measured prior to each defoliation event for each entry. Bahiagrass herbage mass was measured throughout the growing season from June to October. Total RP spread was measured at the end of the growing season in October. To evaluate the effects of establishment across multiple years, a new experimental site was established in March 2012 in order to have a second year of evaluation.

The grazing intensity and frequency study was planted in July 2010 using four different RP ecotypes and was allowed to establish through the remainder of the 2010 and all of the 2011 growing seasons. Defoliation management will begin during summer 2012. A second year of data will be collected on this experiment in 2013.

The soil study was established at the Plant Science Research and Education Unit (Citra, FL) to quantify the effect of forage management systems on soil C and N. Initial soil cores were taken from each plot prior to forage establishment to quantify total C, N, and bulk density. Additional soil cores were taken to 20 cm which will be analyzed for soil organic matter fractions. In March 2011, Florigraze RP plots were established using rhizomes. In June, bermudagrass plots were established using vegetative sprigs. Both forages were allowed to establish throughout the summer growing season. In November 2011, plots with winter management treatments were overseeded with Florida 401 rye and allowed to establish until January 2012. Beginning in January, management treatments were imposed and rye was either clipped or grazed monthly until March 2012. Grazed and hayed plots were sampled monthly for herbage mass and nutritive value. At the end of the winter growing season in March 2012, plots were sampled for residual herbage mass as an indicator of potential aboveground C and N pools.

Impacts and Contributions/Outcomes

Preliminary results indicate that the establishment of RP via strip-planting in bahiagrass swards may be a viable option for pastures in the SE USA. Development of new technologies may reduce establishment costs of RP, decrease the need for commercial fertilizer, and increase nutritive value of grazed pasture systems. Therefore, these technologies may lead to the development of more sustainable, low-input pasture systems in Florida. Data from the described experiments at the Beef Research Unit will be a key focus of a producer-based Perennial Peanut Field Day in Gainesville, FL in July 2012.

The results of the soils study are expected to quantify the potential of a range of forage systems to provide ecosystem services through improvements in soil quality while maintaining pasture productivity. Additionally, overseeding of RP with rye will provide practical recommendations on winter management where there is a relative lack of knowledge. Increasing soil productivity and utilization of these pasture- based systems may lead to economically and environmentally sustainable practices which can be implemented by producers in the region.

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