Research Update: Variability in Dry Matter Content of Harvested Corn for Silage
Adapted by Jennifer Heguy, UCCE Stanislaus/San Joaquin, Betsy Karle, UCCE Glenn/Tehama, Patricia Price, SRA, UC Davis, & Deanne Meyer, UCCE Waste Management Specialist, UC Davis
Do you know how much dry matter is being removed from your corn fields and placed into your silage structure? The answer to this question has many implications, including: cost of harvesting forage, maintaining accurate feed inventory as well as regulatory compliance.
Our objective was to determine if differences exist in calculating dry matter (DM) removal based on various intensities of sub-sample and composite collection. We collected a representative sample and noted the forage weight from every truck unloaded from a single corn field on three dairies. Actual DM removed was calculated by summing truckload weight * DM for all collected samples. Field DM removal totals were calculated using two composite sampling methods (sequence and interval). Sequence values are the average of sample DM within an hour of harvest; for example, forages from trucks that unloaded between 9a and 10a (see Figure 1). Interval values are the average of every 10th sample collected, for example, forage that was unloaded at 9a, 10a, 11a, etc.
We found that taking a single sample of forage to estimate DM removal of an entire field yielded results that varied greatly from the actual DM removed. Using any one individual sample to estimate DM removal could underestimate harvested forage by 21.5% or overestimate forage removal by 20.4%. Sequential composites were less varied, and interval samples were the least varied of all methods tested (see Table 1).
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