Project coordinator Wilbur Miller’s goal is to maintain a sustainable ranch with a minimum of off-ranch inputs. He raises cattle, markets weaning calves and sells some grass hay, using no pesticides or herbicides and a limited amount of commercial fertilizer in the form of ammonium nitrate and phosphate. In this project, he assessed whether it is economically feasible to stop using chemical fertilizer on his grass hay.
Miller established five parallel plots 55 feet wide and 1/8 mile long, selected so the fertilizer truck could made one pass on each plot with a different rate and mix. Soil samples from each plot were sent to the soil lab at Colorado State University for 2002 and 2003 to determine the ammonium nitrate and phosphate needed to produce 3.5 tons of hay per acre per year.
The plots were irrigated as needed from May 15 to Oct. 15 and hay was harvested from the five plots on July 13 and 14 for both years. After hay harvest, cows and calves grazed regrowth until Oct. 15 for both years. Hay samples from the five plots were sent to Fast Test Forage Lab in Eaton, Colo.
The project analyzed soil samples, forage production and forage quality. Soil test results were uniform in 2002, except for plot 4, which had a much higher level of residual N and P. Miller had no explanation for the difference. Indeed, in 2003 soil test readings were fairly uniform across all five plots. For three of the five plots, the application of phosphate needed to achieve the yield goal changed by 40 pounds per acre.
As for hay production, plot 1, which received no fertilizer, had the highest yield in 2002, 72 pounds above average production of 3,442. The yield average in 2003 increased to 3,917 pounds per plot, which Miller attributes to nitrogen-fixing electrical storms, which then applied the nitrate with the rain.
Hay test samples for 2002 showed protein at just under 10%, total digestible nutrients(TDN) at just over 50% and relative feed value (RFV) at just under 100. In 2003, protein levels increased in all plots to above 10%, except for plot 3 at 15.1%, which is excellent for grass hay. TDN was about the same as in 2002, while RFV was just over 100 for all plots except plot 2.
BENEFITS OR IMPACTS ON AGRICULTURE
Miller said his study established that he should not fertilize the hay fields that have similar soil types as his test field because the control plot, with no fertilizer, produced as well as the fertilized plots. He estimates that would save him about $12 in production costs for each ton of hay produced, or an average annual savings for his ranch of $7,200.
The downside, he said, is a possible reduction in protein level, although the control plot in 2003 did have a protein level of 13.9%
The environmental benefit of eliminating chemical fertilizer would be a reduction of 8 tons a year of nitrate and 4 tons of phosphorus for Miller’s ranch.
“This chemical fertilizer application elimination will make our ranch hay production much more sustainable because the only off-ranch inputs will be hay-harvesting machinery and fuel,” says Miller. “Elimination of chemical fertilizer will eliminate the potential for nitrate leaching and off-flow water carrying phosphorus into the groundwater and streams.
Miller said that neighboring producers are interested in his project and want copies of his project report.
Miller is contacting Hay and Forage and the Western Farmer-Stockman magazines.