In our consumer society, the growing need for food increases due to an increase in population. According to Keeney (1997), the world population is expected to increase by 2.3 billion. Our natural lands are insufficient in necessary nutrients that are important for plant nutrition and the productivity of the crop.
In order to meet the growing need for food, the farmer uses chemical fertilizers to achieve maximum efficiency and good quality products. But recently the application of chemical fertilizers increased throughout the world and it’s expected that by 2020 about 70% of grain yield will have to depend on chemical fertilizer.
Excessive use of chemical fertilizer causes long term imbalance in soil pH and fertility. Its exponential use also leads to many health-related issues as well as environmental problems such as it causes nutrient pollution of water because chemical fertilizers are excessive in nutrients. Nutrient pollution is the process where too many nutrients mainly nitrates and phosphate are added to waterways and impure our water quality. Chemical fertilizer is the primary source of nutrient pollution of water. When chemical fertilizers are not properly utilized by the plant, they can be lost from farmland and negatively impact downstream and surface water quality. In the agriculture area, nutrients are added into the water reservoir by three ways such as;
1. Drainage
2. Leaching
3. Flow
Soil does not absorb the excess nutrients, which then move downward freely with drainage water. In agriculture, due to rain and irrigation, water-soluble plant nutrients loss from the soil into water reservoirs through the process known as leaching. Nutrients leached out by agricultural practices such as fertilizing and cultivation.
Plants used only 50% of chemical fertilizers that applied to the soil, 2 to 20% lost due to evaporation 15 to 25% react with an organic compound of soil and 2 to 10% obstruct ground and surface water. In European countries, nitrate concentration in groundwater is 23mg/L and 45mg/L in the USA.
Nutrient pollution of water leads to many serious problems such as nutrients act as a fertilizer and promote the algal growth on the water surface, through the process is known as “Eutrophication”.The explosive growth of algae reduces the level of dissolved oxygen in the water.
Algal blooms block the light pathway that is needed for underground water species such as seagrasses to grow, as a result, they die and their decomposition leads hypoxic( oxygen present in low level) and anoxic(oxygen completely absent) condition in water. Hypoxia caused the animal to become physically stressed while anoxia can kill them. Nutrients along with drinking water cause Methanoglobinaemia and also cause stomach and liver illness, respiratory and neurological issues. Nutrient pollution negatively influences tourism due to foul odor and unsightly views.
It’s the largest pollution affecting the coastal water of the United States (Howart et al 2000). More than 40% of streams have a medium to the high levels of nutrients. Approximately 4 million lakes acres identified as threatened and impaired. About 60% of coastal rivers and bays are affected by them. Nutrient pollution is felt in the form of massive death zones such as those in the Gulf of Mexico and the Chesapeake Bay. It also affects three Gorges’ reservoirs areas.
Some of the steps by which we can reduce nutrient pollution in water are as follows;
Farmers should espouse nutrient management techniques by applying chemical fertilizers in a balanced amount at the right time.
Farmers should evade applying fertilizers near to waterways. Particularly during wind storms and rainy days.
Farmers should plant trees around their farms. It can help to prevent nutrient loss from the field by absorbing nutrients prior to they reach water bodies.
In the end, it is especially requested for farmers to avoid the excessive use of synthetic or chemical fertilizer and play a key role to save our water reservoirs.
The writer is a student of M Phil at PMAS arid agriculture university Rawalpindi.