Development and Evaluation of Organic Forage Systems for the Mid-South, USA.

There is increasing interest in organic livestock production in the Mid-South, but limited research information in organic systems from this region is available. A key issue for organic forage production is the need for species mixtures containing sufficient proportion of legumes to support sward nitrogen needs, readily establish to compete with weeds, and produce sufficient forage quality throughout the entire grazing season given climatic conditions and highly weathered soils in the region. To begin evaluating these questions we established a replicated experiment at The University of Tennessee’s Organic Crops Unit (UTOCU) in fall 2010 and a replicated field-scale experiment at a certified organic dairy in eastern Tennessee in spring 2011. Forage systems evaluated at the UTOCU included four perennial mixtures and one warm and cool-season annual rotation: (1) alfalfa , (2) red clover , (3) alfalfa-orchardgrass , (4) red clover-orchardgrass, and (5) wheat-crimson clover mix followed by sorghum-sudangrass. Forage systems evaluated in the on-farm study included (a) an annual mixture (wheat-crimson clover followed by sorghum-sudangrass/cowpea), (b) cool season perennial (red clover) overseeded with a warm-season annual (crabgrass) and (c) perennial mixture of tall fescue (cv. MaxQ)-red clover-white clover. Forage yields and quality, weed populations, and soil quality were evaluated in both studies. During the 2011 season, total herbage yields at the UTOCU were greatest from the annual mixture and from mixtures containing red clover (> 9,815 kg ha^-1). Alfalfa yield in monoculture was limited at the initial harvest by incidence of sclerotinia stem and crown rot, but in mixture with orchardgrass total yield was statistically equivalent to red clover treatments likely due to yield compensation effects. The proportion of nonsown species at the UTOCU was similar among perennial mixtures at the first harvest (36 to 52% of dry matter), but was minimal by the second year (<5%) which suggests these mixtures would be useful for weed control as part of sod-based rotations.