Determining Limits of Soil Moisture Regime Using Net Ecosystem Exchange and Components

This study explores the feasibility of identifying the effective soil moisture regime limits of a rainfed corn farmland (in Southern Maryland, USA) to investigate soil water stress that impact carbon uptake and corn yield. Soil moisture regime are defined based on approximation which sometimes may be misleading. Identifying the right limits can be useful in the identification of drought and flood which are responsible for soil moisture stress in corn during growth. The parameters analyzed in this study project were micrometeorological observations from flux tower and soil moisture (for the first 90 days after seeding), as well as corn yield data for the growing seasons 2006 – 2014. A statistical analytical approach that involves Pearson correlation were used to investigate relationship amongst the parameters. The ninety days period comprises of the vegetative and reproductive growth stages of corn before the maturity stage. Understanding the role of sm in various sub stages sensitive to sm of these major growth stages is very critical for effective sm management in predicting optimal carbon uptake and corn yield. Coupled to the role of corn growth stages is also the role of soil moisture regimes, which are (available water content (awc), permanent wilting point (pwp) and field capacity (fc)). From the analysis the pwp and fc, which together form sm stress show very strong correlation with NEE (net ecosystem exchange) and components and corn yield. Based on this approach the final analysis shows that drought and flood events were responsible for the low yield and NEE output over the rainfed agroecosystem.