Theses and Dissertations

Date of Award

12-2022

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Agricultural, Environmental, and Sustainability Sciences

First Advisor

Dr. Engil Isadora Pujol Pereira

Second Advisor

Dr. Alexis Racelis

Third Advisor

Dr. James Jihoon Kang

Abstract

Mechanized tillage is known to impact the dynamic physical, biological and chemical properties of a given soil, and as a result, can cause systematic harm to the soil’s function (Alam et al., 2014). The aim of this study is to assess how a series of land management tillage practices will impact dynamic physical and biological soil health parameters such as aggregation, carbon, respiration, and enzymatic activity (β-glucosidase). According to Acir et al (2020), the aforementioned soil parameters are both co-influenced and dependent, indicating a response to tillage is likely. A total of 198 samples of Hidalgo series soils were collected from a series of 11 agricultural (AS) and ecological reference (R) sites. Samples were collected from Anaqua Farms (AS) located in Lyford, TX (26°23’41.1” N, 97°48’57.5” W), the Hub of Prosperity (R) located in Edinburg, TX (26°18’32.7” N, 98°12’11.1” W) and a third farm (R) located in Raymondville, TX (26°24’48.9” N, 97°47’21.3” W). Samples were collected by both the Edelman probe and surface cores in an effort to gather the entirety of one meter within the soil profile. The onemeter samples were separated by horizon depths (D1: 0-5cm, D2: 5-10cm, D3:10-30cm, D4: 30- 50cm, D5: 50-80cm, D6: 80-100cm), sieved (8 mm), air dried and ultimately assessed through a series of laboratory procedures. Samples were run through the Wet Aggregate Stability lab procedure, Active Carbon (POXC) by oxidation of organic matter and the measurement of β-glucosidase by extraction and colorimetric reading of p-nitrophenol release all based off the Kellogg Soil Survey Laboratory methods manual. Soil respiration was additionally measured under the rewetting of air-dried soil by sealed chamber alkali trap respirometry using the Cornell Soil Health Manual. Results for all measured indicators of health showed a significant decrease in depth by management for conventional, strip and intermittent tillage sites in the 0-5cm depth when compared to the undisturbed ecological reference sites. Additionally, when comparing depths by respective managements, we see the highest comparison in the top of the soil profile for the undisturbed sites when compared to all other depths for respiration, β-glucosidase, and aggregation measurements. This could indicate that Hidalgo sandy clay loam soils are impacted by frequent tillage and as a result of this physical and biological disturbance, we see a decrease in active carbon, microbial activity and soil aggregation.

Comments

Copyright 2022 Rocío N. Hernandez. All Rights Reserved.

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