Semester of Graduation

Spring 2022

Degree

Master of Science (MS)

Department

School of Plants, Environmental and Soil Sciences

Document Type

Thesis

Abstract

Nitrogen (N) is a crucial nutrient for proper plant growth and development. N deficiency results in poor tillering and thin, short internode stem production for sugarcane production, thus resulting in low cane tonnage. Therefore, proper N fertilizer management is essential for a sustainable sugarcane production system. This research was conducted at the LSU AgCenter Sugar Research Station in St. Gabriel, LA, from 2019 to 2020 at three Sites (Site 1, 2, and 3). The treatments consisted of different N rates (0, 45, 90, and 135 kg N ha-1) and sources (urea-ammonium-nitrate solution [UAN]-32%, 30-day [Coated Urea 1], 45-day [Coated Urea 2], 60-day [Coated Urea 3]) arranged in a randomized complete block design with four replications. Soil samples at two depths (0-15 and 15-30 cm) and second top visible dewlap leaf blade samples were collected from each plot at two, four, eight, and sixteen weeks after N application and at harvest to determine soil ammonium (NH4+) and nitrate (NO3-), and N content, respectively. Cane yield was determined by harvesting the whole plot with a chopper harvester and weighing the billets in a wagon equipped with load cells. Sugar yield was calculated as the product of cane yield and theoretical recoverable sugar (TRS). Unlike the N source, the rate significantly affected cane tonnage, sugar yield, and N content in stalks and leaves across sites (p-1. The increase attributed to N application was 16 Mg ha-1 for cane tonnage and 2,255 kg ha-1 for sugar yield. Site 3 achieved the highest cane and sugar yield among the Sites. The heavy-textured soil at Sites 1 and 2 and several heavy rainfall events during the tillering stage might have affected sugarcane growth and N transformations. The coated urea-treated soil maintained a level of N about 40 % higher than the UAN-treated plots across sampling dates for Sites 1 and 2. The findings from this research demonstrated (a) the influence of weather conditions and soil type on N transformation and availability, (b) the utility of coated urea as an N source, and (c) that UAN is an effective N source.

Committee Chair

Brenda Tubana

DOI

10.31390/gradschool_theses.5576

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