Earth day

1. Earth day The use of inputs

2. Introduction • Pour augmenter les rendements, l’homme doit constamment intervenir dans les agrosystèmes afin d’équilibrer le sol, lutter contre les adventices et assurer un apport régulier en eau. • Mais ces interventions ne sont pas sans conséquences sur l’environnement. • To enhance agricultural productivity, man must constantly intervene in agrosystems to balance the soil, combat against weeds and ensure a steady supply of water. • But these interventions can affect the environment.

3. Thefertilization • To fertilize agricultural systems and to enhance agricultural productivity, farmers use fertilizers. These fertilizers come from animals or plants. The mixture of animal excrements and urine compose the manure which is rich in nitrogenous organic matter. Mineral fertilizers are produced from minerals from subsoil (phosphate, potash) or from nitrous. Mineral fertilizers can contain only one chemical element: nitrogen (N), phosphate (P), potassium (K) or are composed of several chemical elements NPK.

4. The green tide • For several years there has been a proliferation of algae in the rivers of Brittany and in the bays where the configuration does not allow sufficient mixing effect: water greens and its transparency decreases, it is the eutrophication. These plants, when they are dying, will constitute a nutritional value for bacteria which multiply and consume the dissolved oxygen in the water and cause the asphyxiation of many aquatic animals.

5. The green tide • Intensive agriculture can be the cause of the phenomenon of green tide. Indeed, the nitrates from mineral or organic fertilizers and not used by the plants are found in rivers and it fosters the proliferation of green algae. We observe an "explosion" of algal productivity, which are deposited on the beaches: this is the phenomenon of the green tide.

6. Pesticides • When applying pesticides, a party does not reach the plant. A part of it is scattered in the atmosphere and falls later with rains and another one is found on the ground. • In this case, the chemicals can be washed off by rains and transported by runoff to surface water or penetrate in the ground. One might wonder about the consequences of the use of these pesticides on the soil. • In addition, via the food chain pesticides can affect many living beings. The organisms absorb the toxic substances at the same time that the water and the nutrients. • The concentration of toxins in the tissues increases for each trophic level. • Pesticides represent a real danger for the environment.

7. Conclusion • The use of pesticides has increased considerably during the second half of the 20th century. The growing awareness of the risks they can generate for the environment and for people’s health leads to the development of new strategies. So, the plan Ecophyto ‘s aim is reduce by 50% the use of pesticides until 2018 . It conveys to reason the use of pesticides : reduction of the frequency of the treatment, the reduction of applied doses…