Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Plants, Soils, and Climate

Department name when degree awarded

Plant Soils and Climate

Committee Chair(s)

J. Earl Creech


J. Earl Creech


Grant Cardon


Ricardo Ramirez


Corn (Zea mays L.) hectarage has increased rapidly in Utah and Idaho in recent years due to expansion of the dairy industry, but little is known about corn production practices that optimize yield and quality of silage corn in semi-arid irrigated cropping systems. The objective of this study was to determine the dry matter yield and quality effects of corn hybrids grown in different plant densities and row widths in the Intermountain West. Field experiments were conducted under irrigation in 2015 and 2016 at locations near North Logan, Utah and Jerome, Idaho. The experimental design was a randomized complete block in a split-split plot arrangement with four replications. The whole plot treatment was hybrid (DKC 49-29, DKC 56-54, and DKC 61-88), the sub-plot treatment was row width (76 and 51-cm), and the sub-sub plot treatment was plant density (61,776 to 123,552 plants ha-1 at intervals of 12,355 plants ha-1). The 51-cm row width resulted in forage dry matter yield increases of 4-7% over corn in 76-cm rows. Hybrids differed in response to row width, with no difference detected for the 99-RM hybrid but a significant yield increase for the 106- and 111-RM hybrids by planting in narrow rows. Yield increased quadratically as plant population increased from 61,776 to 123,552 plants ha-1 for all hybrids. The only forage nutritive value that was influenced by row spacing was crude protein (CP), where the 76-cm row spacing showed a 4.5% advantage over the 51-cm row width. Starch increased approximately 3% from the lowest to highest plant densities tested. Net returns showed possible positive increases when comparing row width adjustments. Silage corn yield and quality in the Intermountain West appears to be optimized in 51-cm rows at a plant population between 86,487 and 98,842 plants ha-1.