Date of Award:

1967

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Plants, Soils, and Climate

Advisor/Chair:

Keith R. Allred

Co-Advisor/Chair:

DeVere R. McAllister

Abstract

The influence of agronomic practices on forage production and chemical composition of an orchardgrass-bromegrass pasture mixture was studied at the Greenville Farm, Logan, Utah, during 1960-1964. The soil is a well drained Millville Silt loam that has about a one percent slope and occurs on an alluvial fan. It is high in potash, phosphorus and calcium and is alkaline having a pH of 7.9 to 8.2.

Analysis of the clipping frequency showed that the yield of forage from four harvests was greater than from five harvests. This difference was greater on plots receiving high rates of nitrogen fertilization, and frequent irrigation. Nitrogen, phosphorus, calcium, copper, iron and zinc contents were lower with five harvests.

Forage production increased significantly as the available moisture in the soil increased, producing the highest yields for the 5-day irrigation interval. Nitrogen, copper, iron and zinc in the foliage decreased and phosphorus and calcium increased with increasing soil moisture. On the contrary, potassium content did not show a specific trend with increasing soil moisture.

Nitrogen fertilization increased the forage dry matter production significantly giving the highest yield for 200 pounds of applied nitrogen per acre per season. The percentage of nitrogen in harvested forage decreased up to 100 pounds per acre of applied nitrogen and slightly increased with 200 pounds. Calcium, iron and manganese contents decreased and zinc content slightly increased with an increase in the amount of nitrogen fertilization. On the other hand, phosphorus, potassium and copper contents did not show a consistent trend with increasing nitrogen fertilization.

A difference was noted between the amount of forage produced for different years. However, there was a tendency of decreasing forage yield with increasing age of stand. Nitrogen and phosphorus contents increased and copper, iron and manganese decreased significantly with the increasing age of stand. Potassium, calcium, and zinc contents showed a gradual decrease with the age of forage but there was a fluctuating tendency in their content for different years.

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