Plantain can slash nitrogen leaching from urine patches

The plantain started life as a common weed.

Seed company Agricom has bred the specific plantain genotype and says given New Zealand’s herd of 6.5 million dairy cattle, the forage could make a big dent in nitrogen leaching.

Agricom, Lincoln and Massey university and Plant & Food Research staff have learned how this genotype of plantain, called Ecotain, can function in pasture systems to reduce nitrogen leaching.

From this common flat weed (Plantago lanceloata) Agricom bred and commercialised a forage cultivar – Ecotain. It is part of the firm’s nitrogen management system NSentinel4 that works to cut nitrogen leaching from urine patches.

DairyNZ chose plantain for its Pastoral21 and FRNL forage work aimed at cutting nitrate leaching losses by 20-30%. This work has been in addition to Agricom’s research.

Thorrold says plantain cultivars with the right composition show clear potential to reduce nitrogen leaching, but it’s unlikely that all plantains are equally effective in nitrogen management.

“There is still a lot to be learnt before we can be confident in predicting the farm scale impact of different plantains across NZ. Experience has taught us to test innovations in whole systems, for several years and in different soil types and climates.

Agricom science lead Dr Glenn Judson says though plantain has been used by farmers for many years, research now shows that using this specific genotype effectively can markedly cut nitrogen leaching from urine patches.

“In one research programme, where Ecotain was used in the likely optimal way as much as 89% of nitrogen leaching was cut from the urine patch.”

Ecotain can be used in pasture as a special purpose crop with clover, or in a grass/clover/Ecotain mixed pasture system. It can also be oversown into existing pasture.

Judson says sheep and beef farmers commonly use plantain whereas dairy farmers are more familiar with chicory due to its high feed value and resilience to dry.

“We know that the urine patch is the greatest source of leached nitrogen. You have a cow, for example, grazing across a large area of pasture, about 140 square metres per day. When they urinate, they’re depositing a high concentration of nitrogen into a very small area compared to the size they were grazing, and that small area is the urine patch.

“The plants and soil surrounding the urine patch can’t absorb all that nitrogen, so it’s easily leached away below the root zone and also into the water table.”

Ecotain reduces nitrogen leaching from the urine patch in four ways: it increases the volume of cows’ urine which dilutes the concentration of nitrogen, it reduces the total amount of nitrogen in animals’ urine, it delays the process of turning ammonium into nitrate in the urine patch, and it restricts the accumulation of nitrate in Ecotain-growing soil.