ASSESSMENT OF TEMPORAL VARIABILITY OF KEY SOIL HEALTH INDICATORS WITH MANAGEMENT STRATEGIES

When should we measure soil health? Is there a 'right time' when the value of a soil health indicator will have a high predictive power. This is a very basic and yet critical question that stands in the way of practically implementing soil health indicators for management decisions. Here we will address this question by surveying a small set of well-chosen soil health indicators with a temporal resolution never achieved before. Because soil erosion and repeated disturbance might lead to lower level of soil health and higher variability of individual measurements, we hypothesize that in general temporal variability of soil health indicators will be anticorrelated with average soil health. The proposed research will leverage two long term experiments from the Agronomy Research Farm at the Pennsylvania State University to look at the temporal variability and sensitivity of soil health indicators (1) to tillage strategies and (2) to cover cropping strategies. We have selected a set of four indicators, including three that have been recently validated for their spatial sensitivity to management strategies. Because we expect soil biological activity to be one of the most variable traits throughout a growing season, we have added a fourth novel biological soil health indicator. This indicator developed in our lab is easy to implement, it measures the abundance and size distribution of cells in the soil, we will leverage this experiment to validate this new indicator. This project will i) determine if soil health indicators vary more with time or with management and the interactions between these factors, ii) communicate results to stakeholder including farmers and peer researchers to better inform when is/are the best time(s) of the growing season to sample for soil health assessment for improved prediction power.