Analysis of Bradford Reactive Soil Protein in Agronomic Treatments at the W. K. Kellogg Biological Station

Abstract

Arbuscular mycorrhizal fungi (AMF) colonize over 70% of all land plants and are generally known to be mutualists with plants. They produce a glycoprotein called glomalin, but very little is known about the proteins‘ structure or its function within AMF. Glomalin may play an important role in soil aggregation and be a large component of soil carbon. Glomalin could be especially important in agricultural fields, where soil carbon is depleted through traditional agronomic practices such as tillage. Tillage and high fertilizer input common to conventional agriculture are known to decrease AMF colonization. Organic agricultural or no till practices may better encourage AMF activity, including glomalin production, ultimately leading to higher soil carbon storage and soil aggregation. In this study we compared glomalin production between fields with different agronomic management types at the W.K. Kellogg Biological Station. We estimated glomalin production using the Bradford assay in which glomalin is operationally defined as Bradford Reactive Soil Protein (BRSP). We compared BRSP levels in conventional, no till, low input, organic and successional agronomic treatments. We predicted that BRSP levels would be found in order of highest to lowest levels in the: successional, no till, organic, low input and conventional treatments. After agriculture ceased, we found that BRSP levels rose significantly. Organic and no till agricultural management practices led to higher glomalin levels than conventional agriculture. There was no difference between low input and conventional management. We were not able to draw definitive conclusions regarding seasonal, crop or year effect on glomalin production.