Identifying Diversity and Activities of Soil Microbes Using Pigmentation Patterns on Buried Cotton Strips: A Novel Approach

Abstract

ABSTRACT Soil biology influences soil nutrient cycling and crop nutrition, and yet, the use of synthetic fertilizers supersedes the need for crop producers to improve soil biological health. A big reason is that soil biology is complex and is difficult for the farmers to assess the biological health of their own soils. Two separate studies were designed to test a novel protocol to study soil biology that can easily be carried out by the farmers. We used cotton strip weight loss (CWL) and microbial pigmentation on the cotton strip buried in soil to assess soil microbial communities. In NPKZn experiment, we evaluated how the exclusion of nitrogen (N), phosphorus (P), potassium (K), and zinc (Zn) from crop nutrition affects the microbial community. The second experiment, CCNR, evaluated the effects of cover crop mixes as either grass, broadleaf, or blend (50% grass + 50% broadleaf), alone or in combination with four corn N rates, 0, 45, 90, 180 kg N ha−1, on microbial communities in the soil. We found that P and K are limiting factors, while exclusion of N was beneficial to microbial communities. N rate higher than 90 kg ha−1 was detrimental to microbes; however, cover crops modify this effect. We also found that in the CCNR experiment, brown pigmentation (r = 0.40***) was significantly correlated with CWL. These research conclusions should provide a better understanding of the relationship between pigmentation and soil microbial activity, while this protocol is simple, efficient, and easy to carry out by the farmers.