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Managing fertilizers to reduce

environmental problems

We need to understand that the farmer applies fertilizer so that the plant would take it up and use it for growth. The fact that some of the fertilizer is polluting water means that it is not being taken up by the plant. In addition to being an environmental problem, it also a waste of money for the farmer. The solution is to get the plant to use the fertilizer that is applied.

The key is to ensure that we have a good growing conditions so that the crop can take up and make use of the applied nutrients. It means that we must have a productive crop variety suited to that area, planting must be properly done, pests, weeds and diseases must be controlled, in fact, all operations must be done properly. One important aspect of proper conditions is balanced nutrition. There must be an adequate supply of all of the other nutrients if the crop is to make use of the applied nitrogen and phosphorus.

With nitrogen, it is critical to apply no more than is needed; any excess is certain to contribute to some form of pollution. Soil testing has not been sufficiently reliable to predict nitrogen needs, therefore the crop requirements determined by local testing are also used.

Timing of application of nitrogen is also important. Because it does not remain in the soil for very long, it is usually better to apply small, regular doses. It is best to time the applications to coincide with the periods when the crop needs it the most. This is where fertilizers have a big advantage over manure. It is not possible to control the release of nitrogen from manure. It may occur at a time when the crop does not need nitrogen allowing it to be easily leached out of the soil.

There are a few chemicals which can modify the rate at which nitrogen reacts in the soil and reduce the chance of pollution. Urease inhibitors work by slowing down the rate at which urea is converted into ammonium nitrogen. Nitrification inhibitors reduce the rate at which ammonium nitrogen is converted into nitrates. The idea is to try to produce nitrate in the soil at the same rate at which the crop is using it so that there will be no excess that can be leached.

Slow release fertilizers use physical coatings on the fertilizer granules to control the release of nutrients. Again, the idea is to match the release of nutrients with the rate of uptake by the crop.

Erosion control measures can dramatically reduce phosphorus pollution. Again, balanced nutrition is a key element in that it promotes the rapid growth of plants whose leaves and residue protect the soil from direct rainfall. Reduced tillage and physical conservation measures have done a lot to protect surface water from the effects of phosphates transported with eroded soil.