Forage Performance and Soil Quality in Forage Systems under Organic Management in the Southeastern United States

• Published in: Agronomy journal 2015-09, Vol.107 (5), p.1641-1652
• Main Authors: Inwood, Sarah E. Eichler, Bates, Gary E., Butler, David M.
• Format: Article
• Language: English
• ISSN: 0002-1962; 1435-0645
• DOI: 10.2134/agronj14.0472

Interest is increasing in organic forage production and sod‐based rotations in the southeastern United States, but research‐based information is limited. A replicated field study was established to evaluate productivity and soil quality changes in five organically‐managed forage systems over 2 yr. Systems included four regionally‐adapted perennial systems and one warm‐ and cool‐season annual rotation: (i) alfalfa (Medicago sativa L.), (ii) red clover (Trifolium pratense L.), (iii) alfalfa/orchardgrass (Dactylis glomerata L.), (iv) red clover/orchardgrass, and (v) an annual system of wheat (Triticum aestivum L.)/crimson clover (T. incarnatum L.) followed by sorghum–sudangrass [Sorghum bicolor × S. bicolor var. sudanense (Piper) Stapf.]. Soil quality was compared to two annual vegetable systems, one managed organically and one managed conventionally. Poultry litter was applied to organically‐managed systems in September 2010 (9 Mg ha−1) and in September 2011 (4.5 Mg ha−1). Mean annual forage yield was greatest from wheat/crimson clover and sorghum–sudangrass (12.4 Mg ha−1 yr−1), intermediate from red clover, red clover/orchardgrass, and alfalfa/orchardgrass (10.0–10.3 Mg ha−1 yr−1), and least from alfalfa (7.6 Mg ha−1 yr−1). Soil C (total and particulate organic matter‐C) increased over 2 yr in all forage systems which were similar, and was in most cases significantly lower in vegetable systems. Soil N (total and particulate organic matter‐N) increased in all forage systems and was highest in alfalfa and treatments containing red clover, and lowest in vegetable systems. Results suggest these short‐term forage systems are viable options for regional organic rotations.