Plant Population: A Key for Controlling Corn for Silage Quality.

Farmers in irrigated portions of New Mexico have been steadily increasing their corn plant populations up past 86,000 plants/ha. In what seems to be a race for silage corn tonnage to meet the needs of the state’s dairy farms money could well be slipping out the planter box. Convincing arguments are needed by the state’s consultants and extension agriculture agents to help increase profit margins. A study was conducted at the NMSU Agricultural Science Center at Artesia to look at the effects of population extremes on the components of yield and forage quality characteristics. Final harvest populations were 90,400, 113,800, and 138,600 plants/ha. All were above current university recommendations of 55,600 to 86,500 plants/ha. There was no improvement in dry matter yield across all populations with an average of 11.7 metric tons/ha. Estimated milk produced per ton of forage dry matter was greater from the low population. Some important concepts to communicate regarding a lower planting population are: The fraction of yield as grain is greater at the lower population (43 versus 31 percent); more grain in produced (8961 versus 5455 kg/ha); ear length is greater (15 versus 11 cm); neutral detergent fiber is lower (50.3 versus 54 percent) which results in more net energy for lactation (6.2 versus 5.9 MJ/kg). The plant produces more ears at high density but not more grain. Basic arguments such as these could help consultants to focus resources on water and soil management issues especially in light of declining water tables and tighter profit margins.