Corn for Silage as Influenced by Hybrid Maturity, Row Spacing, Plant Population, and Climate

Most research on corn (Zea mays L.) silage production has been conducted in the northern United States and results do not necessarily apply to growing conditions in the South. Therefore in 1968 and 1969, corn was grown in the Piedmont (elevation 282 m) and Mountains (elevation 584 m) of Georgia to determine the influence of hybrid maturity row spacing, plant population, and climate on silage dry matter yields, percentage ears, leaves, and stalks, and in vitro dry matter digestibility (IVDMD). An early and late maturing hybrid was grown in 51 and 102 cm rows with 49-, 68-, and 86,000 plants/ha in the Piedmont, and a late maturing hybrid was grown in the Mountains in 61, 76, 91, and 107 cm rows with 30-, 45-, 59-, and 74,000 plants/ha. In the Piedmont, yields were not significantly different for the early and late maturing hybrids, significantly higher in 51 than 102 cm rows (11.9 vs 11.3 mt/ha), and increased significantly as populations increased from 49-, 68-, to 86,000 plants/ha (10.5, 11.6, to 12.3 mt/ha). In the Mountains yields were not significantly different for row spacing, and increased significantly as populations increased from 30-, 45-, 59-, to 74,000 plants/ha (17.7, 21.1, 24.4, 26.0 mt/ha). As populations increased from 49 to 86,000 plants/ha at the Piedmont location, ear content decreased from 55 to 45 percent and stalk content increased from 27 to 32 percent. This resulted in significantly lower IVDMD at 86-, than 68,000 plants/ha (63 vs 65.8 percent). In the Mountains as populations increased from 30- to 74,000 plants/ha, less change in ear (57 to 53 percent) and stalk (16 to 18 percent) content was observed with no change in IVDMD with varying papulations. Row spacing did not influence IVDMD at either location. These differences in response to management of corn grown for silage between these locations were attributed to more evenly distributed rainfall and lower temperatures at the Mountain location, and should be somewhat comparable to production response at average northern and southern locations.