Document Type

Thesis - Open Access

Award Date

2019

Degree Name

Master of Science (MS)

Department / School

Agronomy, Horticulture, and Plant Science

First Advisor

Jose Guzman

Abstract

The intensive use of mineral fertilizers to achieve high crop yield has led to soil degradation and poor soil health. Thus, manure application as an alternative to mineral fertilizers can be an effective fertilization strategy to improve soil health and biodiversity. This study aims to assess the impacts of long-term manure and mineral fertilizers on soil physical, chemical and biological properties. The experimental site was initiated in 2003 near Beresford, South Dakota on Egan soil under a randomized complete block design with four replications and six treatments. The study treatments included: three manure rates [low manure (LM), manure application based on the phosphorous requirement; medium manure (MM), manure application based on nitrogen requirement; high manure (HM), two times prescribed nitrogen rate], two chemical fertilizer rates [medium fertilizer (MF), recommended inorganic fertilizer rate; high rate of the fertilizer (HF)], and control (CK, without any manure or fertilizer application). Data from this study showed that bulk density under HM was 19 and 9% lower compared to the CK in 2018 and 2019, respectively. Data from 2019 showed that manure application significantly increased soil wet aggregate stability (0-10 cm) compared with the CK. Particulate organic matter (POM) and soil organic matter (SOM) were increased with manure application compared with the CK. However, inorganic fertilizer application did not impact organic matter components. The HM treatment significantly increased urease, β-glucosidase, and alkaline phosphatase enzyme activities, and soil microbial community PLFA biomass for the 0-10 cm depth as compared to those with CK treatment in 2018. Similar trend was observed for 2019. However, both fertilizer rates (MF and HF) did not show any differences in microbial community for either depth. Carbon and nitrogen fractions were significantly increased with HM treatment but remained unaffected with mineral fertilization. Cold water nitrogen (CWN) was increased under MF treatment as compared to the CK for 0-10 cm soil depth, whereas, both MF and HF increased CWN by 121 and 86%, respectively, for 10-20 cm depth in 2018. Soil quality index (SQI) was higher for the HM treatment as compared to the CK and fertilizer treatments in 0-10 cm and 10-20 cm soil depths, which indicate that manure application improves the soil quality. However, fertilizer treatments did not impact SQI. This study concluded that application of manure for long-term enhances the soil physical, chemical and biological properties as compared to the inorganic fertilizers, however, further study needed which can monitor the environmental impacts that include water quality and greenhouse gas emissions associated with the manure application.

Library of Congress Subject Headings

Manures -- Environmental aspects.
Fertilizers -- Environmental aspects.
Soils -- Analysis.
Soils -- Quality.

Format

application/pdf

Number of Pages

119

Publisher

South Dakota State University

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Rights Statement

In Copyright