Drought Study

HOW THE DROUGHT AFFECTED SOIL IN SOUTHEAST OHIO

KATE RICHARDS

Collection Process

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• Dr. DeForest collected 36 soil samples from the plots shown in the image.
• Brought the samples back to the lab for analysis.
• With the help of wonderful volunteers, the soil was sieved to prepare it for my experiment.

Exchangeable Aluminum

The purpose of an exchangeable aluminum experiment is to see how soil acidity affects aluminum levels, which can block important nutrients like phosphorus from plants, and to find ways to improve soil health by reducing aluminum’s impact.

Enzyme Assays

Understanding Microbial Activity During Drought

• Enzymes and microbes drive nutrient cycling, breaking down organic matter to release essential nutrients for plants and maintaining soil health.

Purpose:

• Measure enzyme activity to assess nutrient cycling under water stress.
• Reveal how soil microbes and ecosystems adapt to drought conditions.

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Nitrate and Ammonium Analysis

• Purpose:
• Measure nitrate and ammonium levels to assess nitrogen availability.
• Study nitrification: the microbial process converting ammonium to nitrate.
• Understand how drought affects soil, microbes, and plant growth.

Soil Organic Matter-� Wet Combustion

• What is it?
• Measures how much organic matter (like plant and animal remains) is in the soil.
• Organic matter is key for storing nutrients, holding water, and keeping soil healthy.
• Why during drought?
• Helps understand how much organic matter is left to support water retention and nutrients, making soil more resilient in dry conditions.

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Impact of Drought on Nitrification, Ammonification, and Microbial Nitrogen Activity in Soil

The graph shows how drought affects the nitrogen cycle in soil:

• Nitrification Rates: The process that converts ammonium (NH₄) into nitrate (NO₃) slowed down a lot during the drought because the microbes that do this work weren’t as active.
• Ammonium Levels (NH₄): Ammonium built up in the soil during the drought since it wasn’t being converted into nitrate as usual.
• Soil Enzyme Activity (NAG): The activity of enzymes that help release nitrogen from organic matter dropped by half, showing that soil microbes were much less active in dry conditions.

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OpenAI. (2024). Data analysis and visualization assistance using ChatGPT (Version 2.0). Retrieved from https://chat.openai.com/

OpenAI. (2024). Data analysis and visualization assistance using ChatGPT (Version 2.0). Retrieved from https://chat.openai.com/

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Drought Effects on Soil Nitrogen and Treatments

• NO3 (Nitrate Levels):
• The "Lime" treatment increased nitrate levels during the drought (+41.85%), possibly due to improved nutrient retention.
• The "Control" treatment experienced a decrease (-16.02%), suggesting reduced resilience in retaining nitrates under drought.
• NH4 (Ammonium Levels):
• All treatments showed significant increases in ammonium during the drought, with "X-tra" having the largest rise (+88.29%). This indicates a shift in nitrogen forms, potentially due to suppressed microbial activity converting ammonium to nitrate.
• Nitrification Rates:
• Nitrification, the process of converting ammonium to nitrate, dropped sharply for all treatments. The "X-tra" and "Lime" treatments were the most affected, with reductions over 70%. This decline suggests that drought inhibits microbial activity essential for nitrification.
• Key Takeaways:
• Lime appears to help retain nitrate levels but struggles with nitrification under drought.
• X-tra retains high ammonium levels but has poor nitrification performance.
• The Control treatment is least resilient, losing both nitrate levels and nitrification capacity during drought.

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OpenAI. (2024). Data analysis and visualization assistance using ChatGPT (Version 2.0). Retrieved from https://chat.openai.com/

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Impact of Drought on Microbial Enzyme Activity

Overall Decline in Enzyme Activity: Drought significantly reduced all enzyme activities, highlighting stress on soil microbial functions.

Key Enzymes Affected:

• NAG: Sharp declines (up to -60%), with "Lime" and "X-tra" showing the largest drops.
• BG: Beta-glucosidase activity reduced by over 50% in all treatments.
• DP (Phosphatase): Most impacted enzyme, with activity reductions exceeding 80%.
• MP (Microbial Phosphorus): Declined across treatments, with "TSP" showing the largest drop (-62%).

Treatment Insights:

• All treatments were negatively affected, but "Lime" and "X-tra" appeared less resilient overall.
• Phosphorus-focused treatments (e.g., TSP) showed slightly better retention of microbial phosphorus.

Takeaway: Drought disrupts microbial enzyme activity, limiting soil nutrient cycling and emphasizing the need for drought-resilient soil management strategies.

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OpenAI. (2024). Data analysis and visualization assistance using ChatGPT (Version 2.0). Retrieved from https://chat.openai.com/

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Soil Organic Matter- WC Results

Lime: Increases SOM by improving soil acidity, boosting microbial activity, and enhancing drought resilience.

TSP: Provides essential phosphorus for root development, indirectly supporting drought-stressed plants.

X-Trt: Experimental treatment shows potential for directly increasing SOM and improving water-holding capacity.

Why SOM Matters: Higher SOM helps soil retain moisture and nutrients, making it critical for crop survival during drought.

• Implementing Lime or experimental treatments can improve soil resilience and reduce drought impacts.

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OpenAI. (2024). Data analysis and visualization assistance using ChatGPT (Version 2.0).

Retrieved from https://chat.openai.com/

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Next Steps?