Low nitrogen crops

What

Planting alternative pasture species with lower nitrogen content can reduce the amount of nitrogen being ingested by animals which, in turn, reduces deposits to pastures and ultimately leaching into waterways. There is also the co-benefit of reducing greenhouse gas emissions.

Why

The amount of nitrogen excreted by an animal is determined by the nitrogen content of it’s diet. Therefore, planting lower nitrogen pasture species can reduce the amount of nitrogen excreted by an animal. This reduces the nitrate load concentrated at the land surface and upper horizons of the soil. When water begins to drain though the soil by deep drainage, there is a lower nitrate loss into the groundwater.

Examples of low nitrogen crops

• Plantain – a key compound in plantain called acubin has been show to lower N~2~O (nitrous oxide) emissions.

• Brassica – studies have found that compounds in brassica can reduce nitrification and lower N2O emissions.

• Italian ryegrass – can reduce nitrogen concentration of urine from animals and improve plant nitrogen uptake in the cooler seasons.

• Fodder beet – can reduce urinary excretion from animals.

• Maize – can reduce urinary excretion from animals.

• Cereals – can reduce urinary excretion from animals.

Also, using plant species which don’t require resowing often is beneficial for reducing nitrate leaching as a lot of nitrogen is lost if the ground is ploughed before sowing. There is a large amount of nitrogen in stubble and roots and when the soil is ploughed, this nitrogen is broken down and vulnerable to leaching.

References