Document Type

Thesis - Open Access

Award Date

2022

Degree Name

Master of Science (MS)

Department / School

Agronomy, Horticulture, and Plant Science

First Advisor

Dwayne Beck

Keywords

Arbuscular Mycorrhizal Fungi, Fertilizer Placement, Fertilizer Rate

Abstract

Phosphorus (P) pollution has become a concern among multiple scientific organizations as it leads to eutrophication, an algal bloom that depletes lacustrine and marine ecosystems of native species. Multiple strategies can be implemented to reduce phosphorus loss from agriculture fields, which is often implicated as a cause of eutrophication. Soil phosphorus chemistry results in phosphate fertilizers absorbing to clay minerals over time. Soil phosphorus is lost from agricultural fields primarily through wind and water erosion. No-till practices prevent soil erosion, which reduces the phosphorus from loading into waterways. Fertilizer placement affects phosphorus loss. Surface application of phosphorus fertilizers increases the risk of loss as rainfall can dissolve the fertilizer and move it into waterways. Arbuscular mycorrhizal fungi (AMF) are soil microorganisms that infect plant roots and form a symbiotic relationship. AMF exchange water and plant nutrients, like phosphorus, with the plant for carbon. Field management practices that support the existence of healthy AMF populations in an agriculture field may allow for a reduction of phosphorus fertilizers. In turn, reduced phosphorus fertilizer rates may result in healthier stream, river, and lake ecosystems. Three different studies took place at Dakota Lakes Research Farm; (1) a phosphorus (P) fertilizer rate study; (2) phosphorus soil placement study; and (3) an AMF soil population study based on fertilizer rate. There were no significant differences between the P-rate treatments [0 lbs MAP (Check), 100 lbs MAP, and 200 lbs MAP, extra fertilizer applied in 2014, 2017, and 2019] and the impact on corn and soybean yield. The P-rate treatments did significantly change the phosphorus soil test levels within the field, with the 200 lbs of MAP having higher soil test levels than the 100 lbs of MAP, and both having higher soil test levels than the Check. Results from the placement study suggest that surface or band applied P did not impact plant tissue concentration, yield, and soil test phosphorus. The arbuscular mycorrhizal fungi populations were affected by the different phosphorus fertilizer rate treatments. The check treatment had significantly more fungi present than the treatments where extra fertilizer was added.

Library of Congress Subject Headings

Phosphorus in agriculture.
Fertilizers -- Application.
Phosphatic fertilizers.
Soils -- Phosphorus content.
No-tillage.
Vesicular-arbuscular mycorrhizas.

Number of Pages

106

Publisher

South Dakota State University

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Rights Statement

In Copyright