The law in many parts of the world increasingly restricts the discharge of agricultural slurry into watercourses. The simplest and often the most economically sound practice returns the material to the land as semisolid manure or as sprayed slurry. This dilutes its concentration in the environment to what might have occurred In a more primitive and sustainable type of agriculture and converts pollutant into fertilizer. Soil microorganisms decompose the organic components of sewage and slurry and most of the mineral nutrients become available to be absorbed again by the vegetation. The excess input of nutrients, both nitrogen and phosphorus – based, from agricultural runoff (and human sewage) has caused many ‘healthy’ oligotrophic lakes (low nutrient concentrations, low plant productivity with abundant water weeds, and clear water) to change to eutrophic condition where high nutrient inputs lead to high phytoplankton productivity (sometimes dominated by bloom-forming toxic species). This makes and, in the worst situations, leads to anoxia and fish kills; so called cultural eutrophication. Thus, important ecosystem services are lost, including the provisioning service of wild-caught fish and the cultural services associated with recreation. The process of cultural eutrophication of lakes has been understood for some time. But only recently did scientist notice huge ‘dead zones’ in the oceans near river outlets, particularly those draining large catchment areas such as the Mississippi in North America and the Yangtze in China. The nutrient-enriched water flows through steams, rivers and lakes, and eventually to the estuary and ocean where the ecological impact may be huge, killing virtually all invertebrates and fish in areas up to 70,000 km2in extent. More than 150 sea areas worldwide are now regularly starved of oxygen as a result of decomposition of algal blooms, fuelled particularly by nitrogen from agricultural runoff of fertilizers and sewage from large cities. Oceanic dead zones are typically associated with industrialized nations and usually lie off countries that subsidize their agriculture, encouraging farmers to increase productivity and use more fertilizer.

1. According to the passage, why should the discharge of agricultural slurry into watercourses be restricted?
1. Losing nutrients in this way is not a good practice economically.
2. Watercourses do not contain the microorganisms that can decompose organic components of agricultural slurry.
3. The discharge may lead to the eutrophication of water bodies.
Select the correct answer using the code given below,
a) 1 only
b) 2 and 3 only
c) 1 and 3 only
d) 1, 2 and 3
2. The passage refers to the conversion of "pollutant to fertilizer". What is pollutant and what is fertilizer in this context?
a) Decomposed organic component of slurry is pollutant and microorganisms in soil constitute fertilizer.
b) Discharged agricultural slurry is pollutant and decomposed slurry in soil is fertilizer.
c) Sprayed slurry is pollutant and watercourse is fertilizer.
d) None of the above expression is correct in the context.

3. According to the passage, what are the effects of indiscriminate use of fertilizers?
1. Addition of pollutants to the soil and water.
2. Destruction of decomposer microorganisms in soil.
3. Nutrient enrichment of water bodies.
4. Creation of algal blooms.
Select the correct answer from the codes given below:
a) 1, 2 and 3 only
b) 1, 3 and 4 only
c) 2 and 4 only
d) 1, 2, 3 and 4

4. What is/are the characteristics of a water body with cultural eutrophication?
1. Loss of ecosystem services
2. Loss of flora and fauna
3. Loss of mineral nutrients
Select the correct answer using the code given below:
a) 1 only
b) 1 and 2 only         
c) 2 and 3 only
d) 1, 2 and 3
5. What is the central theme of this passage?
a) Appropriate legislation is essential to protect the environment.
b) Modern agriculture is responsible for the destruction of environment.
c) Improper waste disposal from agriculture can destroy the aquatic ecosystems.
d) Use of chemical fertilizers is undesirable in agriculture.