Document Type

Dissertation - Open Access

Award Date

2023

Degree Name

Doctor of Philosophy (PhD)

Department / School

Agronomy, Horticulture, and Plant Science

First Advisor

Peter Kovacs

Abstract

In recent years, Sulfur (S) deficiency has been observed in soybean producing regions in the US and different parts of the world. The major factors behind the frequent occurrence of S deficiency are reduced atmospheric S deposition due to strict regulations on emissions from fossil fuels, large S removal from high yielding crops, less use of fertilizers containing S, and intensive cultivation practices. To test S limitations, I conducted two independent studies from 2019 to 2021 at two locations in Eastern South Dakota to determine the effect of foliar and preplant S application on soybean. The objectives of this research were to 1) determine the effect of foliar S application on soybean nutrient uptake, yield, and seed protein and oil content, 2) determine the effect of different S sources and rates on soybean nutrient uptakes, yield, and seed protein and oil content. Treatments in the first study included single foliar S applications at the V4, R2, R3, and R4 growth stages at the rate of 5.6 kg ha-1 and double foliar S applications at the V4+R2, V4+R3, and R2+R3 growth stages each at the rate of 5.6 kg ha-1 . Pre-plant applications, V4 + micronutrient, and dry S application (as broadcast) at the V4 growth stage at the rate of 5.6 kg ha-1 were also included. Similarly, treatments in the second study included pre-plant S application at the rate of 0, 5.6, 11.2, 22.4, and 33.6 kg ha-1 from three S sources: AMS (ammonium sulfate), MES-10S, and Tiger XP. In the first study, double foliar S applications increased leaf and stem S uptake at the R6, but neither foliar application impacted yield, seed protein and oil concentrations. Similarly, in the second study, S application with increasing rates increased S accumulation and partitioning but reduced Sulfur harvest index (HI) at the physiological maturity. S applications across all sources increased yield at the Brookings site only. S applications with increasing rates increased seed protein but decreased oil content and vice-versa. These results indicate that foliar S application in soybean are not likely to increase seed yield or quality under similar growing conditions. On the other hand, preplant S application may be beneficial under limited circumstances, particularly when soil organic matter and soil sulfate-S levels are low.

Library of Congress Subject Headings

Soybean -- Effect of sulfur on.
Sulfur in agriculture.

Publisher

South Dakota State University

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Rights Statement

In Copyright