Document Type

Thesis - Open Access

Award Date

2021

Degree Name

Master of Science (MS)

Department / School

Agricultural and Biosystems Engineering

First Advisor

Lin Wei

Keywords

Bio-based ingredients, Controlled release nitrogen fertilizer, Corn yield improvement, N losses

Abstract

Nitrogen use efficiency (NUE) is an essential factor to increase crop yield. When conventional nitrogen fertilizer (e.g. Urea, Ammonium Sulphate, etc.) is applied in the field, generally over 50% of the N of these fertilizers may lose into the air due to vaporization, or run-off and leaching in rivers and lakes. The N losses lead to not only low NUE but also serious environmental problems. The consequence of N losses results in insufficient N available to meet the demand of crop growth at the growing stages. Lack of sufficient N for crop growth puts a threat of nutrient deficiency and low harvest. Controlling the N release from the fertilizers to improve N availability can reduce the problem and increase NUE and crop yield. This research aims to develop new Biochar based controlled-release fertilizers (BCRNFs) for corn yield improvement while reducing environmental impacts. Biochar was mixed with N fertilizers and other bioingredients and then pelletize into small particles, followed by coating the particles with a biodegradable layer to produce the new BCRNFs. The N release performances of these BCRNF samples were studied. The particles of BCRNF samples were made by two different pelletizing methods. Two different coating methods were applied to coat the BCRNF particles. The N release behavior of the BCRNF samples was investigated. BCRNFs made with 0%, 5%, 10% Bentonite contents and particles dip-coated for single, double, and triple times were analyzed to examine the effect of Bentonite and the number of dip-coated. Biosolid, Bio-asphalt, Rice starch were also applied to make different BCRNF samples that were dip-coated with polylactic acid (PLA) tested for their release characteristics. The effects of these BCRNF samples on corn yield improvement were also investigated in the greenhouse trials. Greenhouse treatments of BCRNFs samples with biobased ingredients showed a better yield than applying pure Ammonium sulfate (AS) and Commercial controlled-release fertilizer (CCRF) in corn production. Approximately 25~29%, and 10~13% yield gained for the made BCRNFs containing Biosolid. To overcome the particle making and coating problems that arose in the previous two BCRNFs, a simple rotatory drum spray-coating system was designed and assembled to make and coat the BCRNF particles. The results indicated that the N release control of BCRNFs with 0% Bentonite is better than that of the BCRNFs with multiple times dip coating, which did not help for enhancing N release performance. The BCRNFs made and coated with the rotatory drum spray-coating system provided a way to apply different coating thicknesses and well-controlled over 70% N release up to 30th days of observation. The spray-coated samples were found with good physical properties and diffusion through the coating layer more predictable than the other BCRNFs tried before. Though there were still some limitations, this research widens the prospects of BCRNFs for corn yield improvement and has a chance to be a competitive product in the market for sustainable agriculture.

Library of Congress Subject Headings

Nitrogen fertilizers.
Biochar.
Corn -- Fertilizers.
Corn -- Yields.
Sustainable agriculture.
Agricultural productivity.
Controlled release technology.

Number of Pages

122

Publisher

South Dakota State University

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Rights Statement

In Copyright