Two years of data from a pasture trial revealed that feeding plantain as a forage crop in a mixture with ryegrass, clover and ryegrass reduces nitrogen leaching by over 50 percent.
Kate Fransen, senior project manger at Dairy NZ. She is also the leader of the Plantain potency, and practice program. Two years of trial data revealed that the Ecotain variety plantain had significant environmental benefits when added to the diets of dairy cows.
Fransen spoke at a Dairy NZ webinar. He said that dairy cows in a Massey University trial were initially grazed on ryegrass pastures. After six days, they were moved to a transition area for six days, and then to a trail area for three days. This was repeated for each grazing during the year. The nitrogen leaching from the trial plots was measured after rainfall. Both the transition and trial plots were irrigated with Ecotain plantain in a mixture of ryegrass & clover.
Fransen stated that plantain can reduce nitrogen leaching through four mechanisms.
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The first two were centered around urinary nitrogen.
We discovered that cows who graze pastures with plantain had lower nitrogen concentrations in urine. They also urinate more often.
Despite the fact that you urinated more, your urine contained less nitrogen. Fransen explained that this meant the urine contained less nitrogen, and therefore leaked less into surrounding environment.
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The trail saw a 60% reduction in nitrate leakage in 2020. It showed a 50% reduction in nitrate leaching in 2021.
Evidence was found that cows that graze plantain emitted more nitrogen from their feces and urine than they did from their urine. She said.
Urine was the most likely to leach nitrogen because it penetrates the environment more quickly than faeces.
Plantain is a good option to slow down soil nitrification.
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Kate Fransen, senior project manager for Dairy NZ says plantain are drought-tolerant and can grow in times when rygrass grows slowly.
By retaining more nitrogen in soil, we can reduce leaching. This is possible through soil nitrification. Nitrification occurs when urine (in the form of ammonia) is converted to nitrate, and leaches into the surrounding environment.
Cows that ate plantain diets had a slower metabolism, so plants had more opportunities to absorb nitrates. Fransen stated that less nitrates were lost in the environment as a result.
Plantains could also reduce nitrous oxide emissions.
The researchers also investigated potential nutritional benefits from milk produced by cows who ate plantain.
Plantain still faces many challenges.
Plantain becomes less palatable as it ages and livestock will prefer ryegrass. However, plantain was preferred by cows during its growth stages when it was more tender than ryegrass.
This challenge was being overcome by management strategies such as mowing the plantain to encourage new development.
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White clover pastures can be reduced by adding the forage herb plantain (to traditional ryegrass)
Although many farmers used plantains in their forage, many others preferred the more popular ryegrass.
Plantain can have higher nitrogen levels than ryegrass, sometimes. Fransen explained that even though the plantain was consumed more frequently, the cows who ate it still excrete less nitrogen into their environment.
This revealed the flaw of the traditional belief that animals with higher levels of nitrogen in their diets would always excrete more nitrogen. She also said that it showed that Ecotain might have a trait that reduces nitrogen excretion.
CORRECTION:An earlier version of this article stated that the transition and trial plots were cultivated with Ecotain plantain varieties. The plots were planted using a mixture of Ecotain, Ryegrass, and Clover. (Amended at 3.47pm on March 30, 2022