Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/14/2014
Publication Date: 2/27/2014
Citation: Kremer, R.J., Hezel, L.F., Veum, K.S. 2014. Ecologically-based management improves soil health in an organic orchard production system [abstract]. Midwest Organic Farming Conference, February 27-March 1, 2014, LaCrosse, Wisconsin. p. 40. Interpretive Summary:
Technical Abstract: Prairie Birthday Farm (PBF), a diversified, organic enterprise on the loess hill landscape in northwestern Missouri, was previously managed as a conventional corn-soybean production system. The soil (Sharpsburg silt loam; fine, montmorillonitic, mesic Typic Argiudolls) is mapped as an ‘eroded soil phase’ likely due to erosion under previous management that resulted in shallow topsoil depth of =5 cm on shoulder to 20 cm on summit landscape positions. Transition to organic farming began in 1995 and included soil organic matter restoration with native prairie establishment and organic amendments. Assessment of soil health was initiated in 2003 to monitor organic management impacts on soil productivity. Objectives of the PBF orchard study are to evaluate ecologically-based practices of integrating native plants in orchard alleys and organic amendments (composts, biochar) on biological indicators of soil health. Surface soils (10-cm depth) were collected annually (2008 – 2013) from three blocks imposed on the orchard site, which included native vegetation, compost and biochar treatments. Conventional orchard and row-cropped sites were controls. Soil organic C (SOC) gradually increased by 25% to > 60 g kg-1 over six years compared with relatively stable SOC of about 30 g kg-1 during the same period at control sites. Soil aggregate stability increased by 70% in orchard alleys, reflecting contributions of established root systems of native vegetation and high SOC. Soil enzyme activities increased by =30% in alley and organically-amended sites, demonstrating substrate contributions from vigorous roots and systematic amendments with organic materials that enhanced soil microbial activity. Microbial community structure and biomass determined by phospholipid fatty acid analysis was similar in compost amended- soils and alley sites under either native vegetation or tall fescue (control orchard); however, all sites were considerably higher than the conventional row-cropped site. Biochar amendment increased major microbial groups (gram-negative and –positive bacteria, total fungi, mycorrhizae) and microbial biomass compared with other treatments. Ecologically-based management at PBF restored and improved soil health on previously degraded landscapes. Microbial diversity improved slightly, however, improved functional diversity (soil enzyme activity, aggregate stability) suggests that microbial assemblages within organically managed soils were more effective in mediating biological processes to achieve improved soil health than in non-organic sites.