The adverse publicity given by the media to agriculture's role in polluting the environment may make farmers feel guilty about using fertilizer. However, reducing fertilizer input can lead to reduced plant growth which can aggravate problems such as soil erosion.
It is important for you to be aware of the effects of fertilisers and to use them carefully, but it is also important that everyone realizes that agricultural fertilizers are not the main sources of environmental pollution. If you apply fertilizers sensibly, so that plants use all the nutrients and none are leached, there is little opportunity for pollution.
1. Phosphorus is a very stable element and moves only 1–5 mm from where it is spread. It binds quickly with soil minerals, so is unlikely to leach through soil except under high rainfall in very sandy soils. It is mainly lost from the soil by erosion when soil particles holding the phosphorus are blown or washed away. For this reason fertilizer phosphorus is unlikely to be a major contributor to phosphate pollution of waterways, unless erosion occurs.
2. Natural waterways face the biggest impact from the use of phosphates. Inorganic forms of this nutrient are most accessible to the plants, but they also wash out of the soil with rain and irrigation. This flushes the phosphates into creeks, streams, rivers, and lakes. When phosphorus levels rise in bodies of water, aquatic plants such as algae and floating weeds can grow out of control, warns the University of California Cooperative Extension. In turn, oxygen levels drop, wiping out fish and other important parts of the underwater ecosystem.
3. The world's supply of rock phosphorus is dwindling. When the mines run out, both farmers and home gardeners alike will no longer just pick up phosphorus in concentrated form. Buying alternative products with organic forms of the macronutrient supports the companies helping make a change to a more sustainable chain for fertilizer.
4. Adverse effect on the fabric mechanical properties versatile to cellulosic, lignocellulose and protein textile and semi durable to durable on flame retardant finishing of cellulosic cotton textile using bio macromolecule, such as DNA from haring sperm and salmon fish.
In many soils phosphorus is limiting to overall crop productivity. Crop production can be limited also by nitrogen which unlike phosphorus is much more easily lost to the environment. When either P or N is lost into the environment they have environmental effects. We want this critical elements in our plants not in our water systems. In relation to N ammonium when absorbed by plants generate soil acidification which can have negative long term effect especially in acid soils. Nitrogen can be provided by legumes and this can be more environmentally and energetic attune to the environment. In terms of P the main goal is to reduce soil erosion to prevent P loss into rivers and oceans. When N and P are lost into ocean estuaries the effect can be rampant algal growth and the de oxygenatin of aquatc resources causing dead zones which have proliferated throughout the World and reduce the productivity of fisheries and contribute to coral reef deterioration. P should be target at the critical seedling stages as starter fertilizer and much of our N should be provided by legumes in our farming system and both N and P are stabilized with manures are utilized with composted plant residues and mineral amendment. An ideal natural amendment providing optimized N and P and can applied directly to plant seeds and seedling is vermicompost. While manures and soluble fertilizers can contribute to N and P issues compost eliminate that negative potential.
The comments made by Dr.Hepperly are relavent to India also.But I have not come across research papers/ reports on water body pollution or enrichment (eutrofication) of P due to P fertilizer or manure application under Indian conditions.
USGS Technical Report 1128 showed about 59% of excess nitrogen in the Chesapeake Bay was due to fertilizer and 30% was from concentrated animal feeding operations and their manure. Cover crops and the use of composts instead of manure can dramatically reduce this problems with excess nutrient.
Fertilizer efficiency according to Mosaic Corporation is related to soil pH. P, N,K have 23, 30 and 33% uptake at pH 4.5 showing that the majority would be lost and not immediately utilized. At pH & 100% efficiency was found of PNK. Liming acidified soils needs to be high priority as well as adjjusting alkaline soils because it is so important to have effective nutrient efficiency.
Di-ammonium phosphate can promote Eutrophication which is considered as one of the most pressing environmental problem. It helps to enrich of surface water bodies with excess nutrients, notably N and P, thereby facilitating the growth of algal biomass as well as other aquatic weeds. The latter leads to an undesirable rise in the biological oxygen demand (BOD) and the chemical oxygen demand (COD) of the water bodies, thereby affecting the several forms of aquatic life and causing the undesirable changes in the aquatic ecosystems, often with serious economic consequences.
With respect, low proportional uptake in the season of application for P and K does not necessarily mean the rest is a pollutant, unless we are speaking of sands or peats.
The role of soil pH has a critical influence on nutrient use efficiency. At pH 4.5 or less acidity makes fertilizer application less than 25% efficient while virtually all nutrient can be used at soil pH of 6.5 to 7.0. For this reason the use of liming and sulfuring to assure the nutrients are coming be available and taken up is so important. Nutrient not taken up by the plants are more likely to lost to the environment causing environmental and health concerns. The importance of pH is critical for conventional and organic agricultural approaches. While this has been known for centuries the application of the technology has not be universally applied and infrastructure and knowledge is not widespread in many areas. Phosphorus is notable in its narrow window of pH to optimize the soil reaction needed for efficient use.
While P is the most limiting of the big 3 nutrients and the most expensive by far the P efficiency can be greatly increased by liming in acid soil pH and sulfuring in high pH soils. The use of mycorrhizae can greatly increase P availability and a quarter dose can give 90% of the optimized crop performance if compared to nonmycorrhizal plants. Cropping systems and mycorrthizale inoculation can do a lot to removal the P issue as well as efficient use of organic amendments such as manures and urine which are high in P.