E CONTENT

POLLUTANTS  FROM  AGRICULTURE

POLLUTION DUE TO USAGE OF FERTILIZERS

ANALYSING:

                                                

Fertilizers are defined as materials which, if added to the soil results    in a better growth of crops. Continuous agricultural activity tends to decrease the soil fertility. Therefore, after each harvest chemical fertilizers must be applied. However, the increasing application of fertilizers has threatened  the human environment and ecology with deleterious consequences. Here  we are going to deal to know more about fertilizers, how they affect environment, their causes and effects. It is one of the major factors in agricultural pollution and therefore they have to be deal with serious concern.

                                                         

·         Fertilizers are chemicals or natural substance added to soil or land to increase

         Its fertility

·         Fertilizers cause many environmental and human hazards.

·         Soil pollution is one of the problem that caused by usage of chemical fertilizers.

·         Nitrogen fertilizers leads to stomach cancer and several other health disorders.

·         Eutrophication is caused by addition of phosphate and nitrate nutrients to lake.

·         Phosphates and nitrates are part of agricultural runoff from a land.

·         Slow release fertilizers use physical coatings on the fertilizer granules to control

                        Release of nutrients.

DESIGNING:             

                                          

Relating to the topic, four images and a video are shown which relates to what are chemical fertilizers their causes and effects. Food crops, like any other plant, require fertile soil to grow. Therefore, after each harvest chemical fertilizers are added. It is Harmful to plants, environment and human beings. The four pictures depict various chemical fertilizers and the video gives an overall understanding on the topic.   

DEVELOPMENT:

                                                              

INTRODUCTION   

Increasing population growth and urbanization, especially in the developing world has compelled the nations to produce more food. Approximately 25% of the world’s crop yield is attributed to the use of chemical fertilizers. Therefore, not surprising that the demand for fertilizers are doubling every ten years. However,  the increasing application of fertilizers has also threatened the human environment  and ecology with deleterious consequences. If unchecked, these harmful effects shall negate, to quiet some extend, the benefits derived from increasing usage of fertilizers.Fertilizers are defined as materials which, if added to the soil nutrients removed by the crop. At least sixteen elements are needed for the growth of plants among these carbon, hydrogen and oxygen are abundantly available in the environment in the form of carbon dioxide and water. These are, therefore, easily restored after each harvest. The remainder are not easily replaced. The below given is the list of nutrients that are essential for plant growth:

Primary nutrients	Nitrogen, Phosphorus, Potassium
Secondary nutrients	Calcium, Magnesium, Sulphur
Micronutrients	Boron, Chlorine, Copper, Iron Manganese, Molybdenum, Zinc

                                                    

 CLASSIFICATION OF CHEMICAL FERTILIZERS   

           

NITROGEN BASED FERTILIZERS:

Nitrogen containing commercial fertilizers are seen in three types, nitrates, ammonium   salts and simple amides. Nitrates being highly soluble in water, are taken up directly by the plants through their roots. Ammonium salts too are soluble in water. Simple amides, such as urea are quickly hydrolysed to ammonium compounds and then nitrified by soil microbes.

PHOSPHOROUS BASED FERTILIZERS:

                                                  

Most manuring schemes aim to increase the solubility of residual phosphates in soil. Unfarmed soils contain negligible amounts of phosphorous. Plants take up phosphorus mainly as orthophosphates. However, orthophosphates are not highly soluble in water. That’s why we try to increase the solubility of residual phosphates in the soil.

                                                          

POTASSIUM BASED FERTILIZERS:

                                             

The potassium released from the sources is rendered easily available to the plants. Therefore, potassium fertilizers have to be added to the soil at regular intervals unless potassium is returned to the soil in the form of fertilizers, the yield of crops will be poor.   

                                           

FERTILIZERS – HARMFUL EFFECTS

                                               

Extensive use of fertilizers is detrimental to the living environment. Following are some of the major environmental problems associated with fertilizer usage.

SOIL

                                       

Highly acidic conditions in the soil tend to inhibit many common bacteria, as the Optimum for most species is neutrality. Soils tend to acquire acidity through repeated use of nitrogen-based fertilizers. As the acidity of the soil increases, bacterial population decreases. Fertilizers harm the soil yet other way. These tend to restore inorganic nutrients to soil, but do not replace the soil’s organic matter. The organic constituents of soil are important because their decay produces humus, which modifies the structure of soil to a level which is conducive.

VEGETATION

                                                 

When soil becomes acidic due to consistent use of fertilizers, a number of chemical and biological conditions set in which are harmful to many plants. Under acidic conditions, nutrient cations, such as calcium and magnesium are leached away from the soil.

HUMAN HEALTH

                                               

Nitrates enters the body of those who consume the meat or milk of the cattle that has grazed on high nitrate – content plants. It will lead to kidney stones in human. Also leads to blue baby syndrome and stomach cancer. Stomach cancer has been associated with concentration of nitrate in portable water. Fatal haemoglobin, which has a greater affinity for nitrite than normal haemoglobin, persists for a few months in the blood stream of a new born.

TESTING

     

The content was tested by a teacher expert in the subject. The way of expressing the topic, the language used, spelling mistakes, content errors, clarity of pictures and relevant video that were put up relating to the topic was checked and suggestions were given. The testing was also done on how much the content was applicable and understandable to the readers and how we can reduce the usage of chemical fertilizers.

IMPLEMENTATION

                                                         

Finally, the content was uploaded in a learning management system where the students can  easily get access to the knowledge they want and they can get a clear idea on the topic  that they want to learn. It was also implemented in SN Trust HSS Kollam among secondary school students to make them understand on the topic harmful effects of fertilizers, their causes and effects on the environment.

EVALUATION

           

The feedback from the learners and instructors are considers for further evaluation. The feedback from SN Trust school students were also collected for further improvements in the content.After checking the feedback, the content is re-designed for effective delivery of the topic.