Soil organic matter fractions and aggregate distribution in response to tall fescue stands

The study was conducted to evaluate the influences of tall fescue management on soil organic matter fractions and macro- and microaggregate distribution. Soil samples were collected from four paired adjacent fields consisting of five years of tall fescue mono and poly stands in Western Kentucky. Soil samples from 0 to 15 cm and 15 to 30 cm soil depths were analyzed for soil organic C and N, particulate organic matter C (POM-C) and N (POM-N), macro- and micro aggregate distribution and C-associated with macro- and micro- aggregates. Significant effects were observed between stands for all the properties, except total C, microaggregates and C-associated with microaggregates. Sampling depth significantly influenced total C and N in both stands. Particulate organic matter C and N and C-associated with macroaggregates and the amount of macroaggregates were strongly affected by tall fescue management. This confirmed the hypothesis that early changes in soil properties were reflected in labile C and N fractions and soil structure. Tall fescue mixture stands had 44% higher POM-C, 50% higher POM-N, 26% more macroaggregates and 33% more C-associated with macroaggregates compared to the tall fescue mono stands at the soil surface of 0 to 15 cm.