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Effects of the Base Cation Saturation Ratio Approach to Soil Management on Weeds and Crop Yield, and Improved Methodology for Measuring Soil Aggregate Stability.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Effects of the Base Cation Saturation Ratio Approach to Soil Management on Weeds and Crop Yield, and Improved Methodology for Measuring Soil Aggregate Stability./
作者:	Leiva Soto, Andrea.
面頁冊數:	1 online resource (152 pages)
附註:	Source: Dissertations Abstracts International, Volume: 84-05, Section: B.
Contained By:	Dissertations Abstracts International84-05B.
標題:	Agronomy. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30165094click for full text (PQDT)
ISBN:	9798352637272

Effects of the Base Cation Saturation Ratio Approach to Soil Management on Weeds and Crop Yield, and Improved Methodology for Measuring Soil Aggregate Stability.
Leiva Soto, Andrea.

Effects of the Base Cation Saturation Ratio Approach to Soil Management on Weeds and Crop Yield, and Improved Methodology for Measuring Soil Aggregate Stability. - 1 online resource (152 pages)

Source: Dissertations Abstracts International, Volume: 84-05, Section: B.

Thesis (Ph.D.)--The Ohio State University, 2022.

Includes bibliographical references

Many Midwestern organic farmers in their focus on improving soil quality for crop production attempt to balance their soil's calcium (Ca) and magnesium (Mg) saturation levels by applying calcium-rich amendments. For most soils, this practice based on the base cation saturation ratio (BCSR) hypothesis, requires repeated applications of calcitic limestone and or gypsum to increase Ca to approximately 65% of a soil?s saturation capacity and reduce Mg saturation to less than 20%. Expected and claimed benefits of this practice of soil balancing include improved soil structure, decreases in weed pressure, and increases in crop yield. We applied various Ca and Mg rich minerals in a corn-soybean-small grain rotation in two Ohio soils over several years. Our treatments were designed to contrast the effects of different Ca to Mg ratios on the weed community and on soil properties. Our research is the first to provide evidence that Ca:Mg ratios in the soil can reduce density of weed seeds found in the soil. At the silt loam soil, broadleaf and grass seedbank densities were on average about 25% and 40% lower after the second year of gypsum applications, respectively, across crops. Weed emergence for the same soil showed a similar response. At the clay loam soil, grass seedbank densities were on average about 40% higher after the third year of epsom application across crops. Our experimental design enabled us to also investigate the claim of soil balancing proponents and farmers that the increases in crop yield they experienced were due to higher Ca:Mg ratios rather than pH correction. We examined crop yield in response to both pH and Ca and Mg saturation levels over 6 years and concluded that balancing the soil Ca and Mg levels did not impact corn or soybean yields but managing soil acidity did. Our results confirm that correcting excess acidity remains the fundamental reason to apply limestone as a tool to improve crop yields. Previously reported research from our project had failed to demonstrate improvement in soil structure resulting from the use of the BCSR approach. Nevertheless, validated and efficient methods to assess impacts on soil aggregation are a crucial need in research efforts to better understand aspects of soil resilience to environmental and man-made stresses. The wet sieving method is a common method used to measure aggregate stability. However, there is a lack of consensus regarding procedures used before, during, and after the wet sieving process. We evaluated various contrasting procedures on eight Ohio soils, having between 7 to 78% sand content, including pre-wetting vs not pre-wetting samples prior to wet sieving, using deionized water vs tap water for wet sieving, sand correcting water stable aggregates after wet sieving (not correcting for sand vs correcting for sand the same size as the aggregate vs correcting all sand), and pre-sieving vs not pre-sieving soil samples prior to wet sieving. Not pre-wetting soil samples prior to wet sieving increased aggregate slaking, while using deionized water or tap water had almost the same effect. Pre-sieving soils before wet-sieving resulted in more water stable aggregates compared to not pre-sieving soils, with less variability across soils. Sand correcting water stable aggregates using the same sieve used for the aggregate separation can lower the variability between soils and have better analytical precision than correcting for all sand sizes or not correcting for sand. Our study confirms observations by soil balancing practitioners on weeds dynamic as increases in soil calcium reduced weed seedbank density while increases in soil magnesium increased weed seedbank density. In contrast, our study shows that for corn, increases in yield were positively related to soil pH and not to changes in soil Ca:Mg ratio. For soil aggregate stability measured by wet sieving, both pre-sieving soil samples prior to wet sieving and sand correcting water stable aggregates with the same aggregate sieve, resulted in lower variability across soils and better analytical precision.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798352637272Subjects--Topical Terms:

2122783
Agronomy.
Subjects--Index Terms:

Soil balancingIndex Terms--Genre/Form:

542853
Electronic books.

Effects of the Base Cation Saturation Ratio Approach to Soil Management on Weeds and Crop Yield, and Improved Methodology for Measuring Soil Aggregate Stability.
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