Date of Graduation

7-2021

Document Type

Thesis

Degree Name

Master of Science in Crop, Soil & Environmental Sciences (MS)

Degree Level

Graduate

Department

Crop, Soil & Environmental Sciences

Advisor

Andrew Sharpley

Committee Member

Kristopher Brye

Second Committee Member

Dirk Philipp

Third Committee Member

Ronald Morrow

Keywords

agriculture, agronomy, crop science, forage production, pasture production, remote sensing

Abstract

More than 38 % of United States’ rural land area was used for grazing (i.e., pastureland or rangeland) ruminant animals in 2017, constituting the largest private land use group. The expansive nature of these lands means that grazing and pasture management decisions have potential to impact water quality as well as profit margins. As a result, beef producers are under increased pressure from economic and environmental standpoints to limit application of nutrients beyond those required to grow the forage needed for animal consumption. At the same time, a large amount of nutrients is recycled back to pasture systems directly from hay fed to cattle. This study evaluated the effects of winter-feeding hay management on soil fertility and forage productivity on a privately-owned beef farm in northwestern Arkansas. In this study, the two common hay feeding practices, using a haybale ring feeder (RF) and unrolling bales (UF), were evaluated over a 2-yr period from November 2015 to November 2017, and compared to an unamended control area. Nutrient analysis of hay fed during the study revealed feeding bales at a rate of 40 bales per hectare (14.8 MG ha-1 yr-1), contained fertilizer equivalent nutrient amounts greater than is recommended for mixed warm season forage crops. After two years of feeding hay, there was in increase in soil K concentration (P < 0.05) in both UF and RF areas, whereas the unamended control was unchanged. There were also differences in soil physical properties between the hay feeding treatments after two years of hay feeding. Mean soil bulk density was less (P < 0.1) for the UF and the control areas after, while the RF areas were unchanged after 2 years. In addition, total mean water infiltration for the UF was greater (P < 0.1) than the RF, while the control area did not differ from either. Also, mean annual forage production was 19% greater (P < 0.1). for the UF relative to the control treatments, whereas for the RF, there was no difference. A second objective of the study was to compare the relationship between remotely sensed spectral derivatives (i.e., vegetation indices) and forage biophysical variables. Imagery from multiple sensors at varied spatial resolution revealed strong positive correlation (P < 0.001) among satellite, UAV, and a handheld crop sensor. Forage biophysical variables, DFY, as well as percent forage N and P, had moderate to strong correspondence which occurred when imagery derivatives were aggregated by season. The finding demonstrates how multiple sources of imagery may be useful in building informative and actionable biophysical models about forage conditions using remotely sensed imagery derivatives from a variety of available sources that may prove to be a useful and efficient tool. Further research focused on assessment of plant phenologic variability during all stages of the growing season is needed in multi-species forage stands. Quantifying and crediting nutrient contributions to underlying soil from winter fed hay, allows farmers to apply less fertilizer to achieve economic optimum yields of subsequent forage crops. The reduction of the fertilizer inputs may result in greater profits for producers, as well as decrease the risk of nutrient runoff into surface waters.

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