Soil fertility is determined by three major elements namely nitrogen, phosphorus and potassium (N, P, K). Nitrogen plays a very important role, therefore urea (containing 46% of N) is a very important component of fertilisers all over the world.

In the past decade, urea has surpassed and nearly replaced ammonium nitrate as a fertiliser. This has brought about new questions on urea and its use.

Urea losses to high irrigation and high rainfall (leaching)

After application to the soil, urea changes to nitrate form, which is available for plants to take up. The nitrification process involves activity of nitrifying bacteria. Nitrogen in nitrate form is very soluble and easily washed away from the root zone with high irrigation or rainfall. This loss is called leaching.

Urea losses to the atmosphere (volatility)

After application to the soil, a chemical reaction occurs when the enzyme urease gets in contact with soil moisture, which allows urea to hydrolyse and convert to ammonia and carbon dioxide. Nitrogen in ammonia, which is in a gaseous state, is lost to the atmosphere within a period of about 48 to 96 hours from the time of application.

The rate of reaction is quicker on high pH soils (alkaline) and high soil temperatures. Unless it rains, urea must be incorporated into the soil to avoid or minimise ammonia (nitrogen) loss. Losses might be quite low in the cold season when the soil temperature is low. Urea losses from leaching and volatility account for more than 60% of nitrogen losses on cultivated field crops.

Slow release of urea

Urea fertiliser can be coated with certain materials to increase the quantity of nitrogen available to plants, thus increasing availability for up-take by plants. These slow-release materials result in more efficient nitrogen use by growing plants. Urea in a slow-release form is popular for use on cereal crops, golf courses, and other special lawn situations.

Zambian Fertilizers Limited has brought to the Zambian market N-Guard, a slow-release neem oil coated urea. N-Guard urea is a research driven, highly concentrated product with potent neem extracts. The benefits of neem coated urea are:

• Inhibition of urea nitrification hence slowing down losses from leaching and volatilisation.
• Reported improved yields of up to 48%.
• Due to the pesticidal properties of neem oil coating, soil born nematodes, termites and other soil pests and diseases are controlled.
• N-Guard Urea is the next generation slow release urea.
• N-Guard Urea can be applied to soil as a solid or a solution or to certain crops as a foliar spray.
• N-Guard Urea high nitrogen content of 46% helps reduce handling, storage and transportation costs over other dry N forms.
• N-Guard Urea, when properly applied, results in crop yield increases equal to other forms of nitrogen.
• N-Guard’s slow release effect of nitrogen results in safeguarding your investment by ensuring that all the applied N is taken up by plant, thereby saving money and labour as no extra N topdressing fertiliser will be required.

The following graphs show results of trial treatments of N-Guard Urea versus competitor products:

Trials conducted by SGS, India. Job Ref: IN/ MUM/AGR/20110898/01. Validation Date- 04/05/2012. SGS Study Code: 0898/01 You too can save money and increase yields with N-Guard Urea.