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2006

Iowa State University

Agricultural Science

Soil science (Soil fertility)

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Evaluation Of Potassium Soil Tests And Methods For Mapping Soil Fertility Properties In Iowa Corn And Soybean Fields , Pedro Aníbal Barbagelata Jan 2006

Evaluation Of Potassium Soil Tests And Methods For Mapping Soil Fertility Properties In Iowa Corn And Soybean Fields , Pedro Aníbal Barbagelata

Retrospective Theses and Dissertations

Improving the use of soil testing in production agriculture may result in increased nutrient use efficiency and profitability. Three studies were conducted in Iowa with this general goal. One study assessed the impact of soil sample drying on K extraction and developed field correlations of an ammonium-acetate K test (AA) based on field-moist samples for corn and soybean. Potassium extracted with AA from dried samples was higher than K extracted from moist samples. The difference increased with increasing drying temperature, was inversely related to the soil K level, and varied among soil series. The moist AA test correlated better with ...


Use Of Precision Agriculture Technologies In Studying The Relationships Among Soil Ph, Calcium Carbonate Equivalent, Soybean Cyst Nematode Population Density, And Soybean Yield , Natalia Rogovska Jan 2006

Use Of Precision Agriculture Technologies In Studying The Relationships Among Soil Ph, Calcium Carbonate Equivalent, Soybean Cyst Nematode Population Density, And Soybean Yield , Natalia Rogovska

Retrospective Theses and Dissertations

Iron deficiency chlorosis (IDC) and soybean cyst nematode (SCN; Heterodera glycines) infestation are major factors that contribute to soybean (Glycine max Merr.) yield reduction in the Midwest. The IDC is often associated with soybean grown on high pH, calcareous soils. In addition, it was documented that SCN population density is higher in high pH soils. The objectives of this paper were to assess the proportion of within-field soybean yield and SCN variability that could be explained by soil pH, calcium carbonate equivalent (CCE), and a previously defined alkalinity stress index (ASI). Aerial images from 21 fields planted to SCN-resistant or ...