When should I worry about my forage? 

Prussic acid and Nitrate poisoning can have severe health implications for livestock and may even cause death. It is important to check the quality (safety) of forage particularly after any event that may retard plant growth or induce stress.

Events that may cause the risk of Prussic acid and Nitrate poisoning include:

• Drought
• Any stress that may retard plant growth
• Environmental extremes (from frost to heat stress)
• Nutrient depletion- particularly phosphorous, potassium, sulphur and molybdenum
• Excessive accumulation of Nitrogen in soil;

1. Reduced leaching
2. Overuse of nitrogen containing fertilisers
3. Overstocking in small areas

What are Nirtates?

Nitrates accumulate in the plant when freely available in the soil. These nitrates concentrate heavily at the lower portion of the plant stem and can be toxic to stock when consumed in large quantities.  Symptoms of nitrate poisoning are generally the result of gastrointestinal inflammation and include diarrhoea and salivation. 

Further, in normal digestion, nitrates are converted to nitrites and then to ammonia. If toxic levels of nitrites accumulation before conversion, nitrite poisoning can occur. Nitrite poisoning can result in death by respiratory paralysis.

Nitrate accumulation in plants generally occurs in two scenarios:

1. When the rate of plant growth abnoramly decreases, yet the uptake of nitrogen continues at a pace that is no longer relative to growth
2. When crops are grown in soils that have high levels of nitrate

Nitrate accumulation in soils generally occurs after:

• Drought
• Overuse of Nitrogen containing fertilisers
• Nutrient deprivation, particularly sulphur and molybdenum
• Overstocking and confinement of livestock. Accumulation of urine and faeces increases nitrate levels in soil.