This is an endless debate about chemical versus organic fertilizers.Why are we so touchy about this issue..?? Why dont we raise this issue of large scale use of pesticises/ herbicides / fungicides versus their organic counterparts which damage the system more consequentially in space and time than chemical fertilizers .

Without doubt , chemical fertilizers , since large amount of assimilable nutrients become available at a given growth stage , much beyond the utilisation capacity of plant being raised , resulting in large scale eutrophication of water bodies..

Rate of release (say, kg nutrient/year) will be lower for organics but the total amount released, which is the actual question, absolutely depends on the total dump load.

Please note that the release amount for water bodies can not be in kg/ha. It has to be something like mg/L surface water.

Chemical fertilizers omit larger amounts of nutrients into water due to the high concentration of these nutrients in chemical fertilizers compared to organic as well as the rate of dissolving of chemical fertilizers in water.

There is no simple answer to this question. Assuming the same amount (kg nutrients / ha) of either organic or chemical fertiliser is applied, the losses to surface waters will depend on method of application, timing of application and plant growth stage. If either organic or chemical fertilisers are applied improperly (or if there is a significant rainfall event shortly after application), the potential for losses to surface waters is high. Plants typically cannot access all the nutrients in either organic or chemical fertiliser so there will ultimately be some losses from either type.

Finally, I must comment on Dr. Dabi’s Statement about units. It is reasonable to quantify fertiliser losses in areal units of kg nutrient / ha, but from a management perspective, the relevant units are probably related to change in surface or soil water concentration, which should be expressed in volumetric units, e.g. mg/l

A chemical fertilizer is defined as any inorganicmaterial of wholly or partially synthetic origin that is added to soil to sustain plant growth. Organic fertilizers are substances that are derived from the remains or byproducts of natural organisms which contain the essential nutrients for plant growth.

Its chemical fertilizers because they often emit higher nutrients causing eutrophication when used in farms closer to water bodies.

Kindly read my recent article on 'The impacts of human activities on the aquatic biodiversity of Lake Bosomtwe...' on my RG page. The full text is available for your download Best regards

Dear Dr. Shervin Jamshidi, both chemical and organic fertilizers are contributory to Eutrophication unless used wisely. It is aggravated highly by unwise use of chemical fertilizer'

http://www.fao.org/docrep/w2598e/w2598e06.htm

This is an endless debate about chemical versus organic fertilizers.Why are we so touchy about this issue..?? Why dont we raise this issue of large scale use of pesticises/ herbicides / fungicides versus their organic counterparts which damage the system more consequentially in space and time than chemical fertilizers .

"Spectacular idea" dear Dr. Anoop Kumar Srivastava

While the nutrient release in Chemical Fertilizer may be quicker, the adverse impact they make also need to be taken into account.

Many school of thoughts advocate that current say hydrid varieties are more responsive to chemical fertilizers than organic fertilizers.While traditionally grown ruling varieties respond more comprehensively to organic fertilizers than inirganic fertilizers. This is the reason , researchers have divided opinions when we talk of response of current day varieties under organic farming than conventionally practiced modern day intensive agriculture. ..

The reason that modern varieties have greater dependency on inputs than traditional heirloom varieties relates to way these modern varieties are produced. These are identified in high yield environments and selected under inputs to differentiate the highest producers. Such an approach does not put much emphasis on defensive characters which are more appreciated by traditional agriculturalists. The modern day farming system is designed for the use of inputs this increases the responsiveness of the genetics and selects away from varieties which have high responses under constrained environments.

I also agree with what others said and chemical fertilizers may emit more nutrients, since most of the them are high analysis fertilizers with high quantity of nutrients on percent weight basis. For instance urea will be having 46 % of N, whereas organic manures hardly exceeds 1 to 2 % of N.

However there are many factors such method of application, timing of application, rainfall intensity, soil type, leaching factor of that particular nutrients, mineralization or decomposition processes, plant uptake etc. Hence all these will ultimately affect the quantum of nutrients reaching surface water.

Then as rightly pointed out by Dr. Anoop Kumar Srivastava , we need to be more cautious about the pesticides/ insecticides/ fungicides/ herbicides/ pharmaceutical wastes/ antibiotics/ medical wastes when we consider the surface water bodies rather than fertilizers.

Nice post Dr Surendran , appreciate it ...

Another very important issue in the context of on-going discussion , is the shelf life of residues , compare the shelf life of residues of fertilizers against the residues of pesticides/fungicides/herbicides in the soil. Such issues hardly come in the way of our discussion. I am happy that you have nailed such issues....

Sorry Paul , i missed to respond to your nice and informative post . I agree with you . How do you expect that such varieties will ever be able to to carry the burden of producing such an exceptionally high yield under organic farming scenario. I personally feel, it is simply out of the context.

Can we really comment on this issue without having some experimental data with well defined conditions?

Organic fertilizer is different from mineral fertilizers in terms of chemical composition, decomposition method, amount of nutrient release, how and nature of that element, chemical fertilizers, rapid decomposition, rapid release of nutrient, which is rapidly lost from soil by washing, etc. Organic fertilizer is slow to decompose but enriches the plant with nutrients

Rightly said Dr. Anoop that it is an endless debate Organic vs. inorganic. Surely, chemical fertilizers having high concentration of nutrients and readily soluble in water are a threat to the ecosystem, I would surely like to know the stability of coated fertilizers like neem coated urea. How far the encapsulation is able to control the rapid outflow of the nutrients from the inorganic source of fertilizers.

Organic fertilizers release the nutrients gradually. The release of nutrients from chemical fertilizer in to water bodies depends upon the location of farm land and application rate.

Soil has its own absorption capacity and when concentration of a specific nutrient in soil exceeds its absorption capacity, it enters into water bodies as in case of P.

At first, It is clear that chemical fertilizers have higher nutrients content per kg. I am Agree with you all. But farmers may use less chemical fertilizers in volume rather than organics in a same condition.

Second, Organic fertilizers release nutrients gradually which pop up this probability that they may be washed out more rapidly by precipitations than chemical fertilizers.

Stabilized organic materials such as composts have much less tendency to lose nutrients into the environment. Whether organic amendment or synthetic fertilizers are used they should be targeted to the time in crop development when they are needed. Phosphorus as an application near the seedling root zone, nitrogen as a lay by at the period of grand vegetative growth and potassium at following and grain fill. Raw manures should be used as ingredient in composts which provide a stabilized source of nutrients which have longevity. Syntethic chemical fertilizer applied in a subsoil drip would avoid much of the loss issues if not over applied. The ability of nutrients to be used and reutilized is a function of organic matter and in soils low in organic matter and high in coarse sand the losses are particularly dangerous.

This is not an easy task I guess. Organic fertilisers are not in typically-known chemical compositions. Each can have different interactions with differing soil conditions. Therefore it would be better to discuss this fact in well defined conditions. For example organic amendments usually keeps higher phosphorus availability for longer term. Its counter-part chemical fertilisers elevate soluble P for couple of weeks. If no extreeme wheater occasion happens during this period P do not significantly leach-away whereas organic fertiliser keeps higher level of soluble P may cause larger amount of leaching due to higher extreeme storms occurrence probability in long term..

In terms of P losses raw manures on soil surfaces are problematic. Compost and disked in compost have much less loss potential.

Chemical fertilizer emits more than organic,

I agree with the other answers. Nutrients load emissions to the environment are higher with chemical fertilizers than with organic fertilizers.

At equivalent rates, how does the two sources behave with respect to annual versus perennial crops or acid soils versus alkaline soils. Its so many growing conditions that turn such comparisons so unrealistic and equally unreliable...

Chemical fertilizers have nutrients content/kg higher than organic fertilizer. Organic fertilizers are applied before planting and irrigation during soil preparation. It is lost by washing from soil faster than chemical fertilizer, as well as it is slow release under rice flooding conditions.

Se deben usar los dos tipos de fertilizantes de forma técnica y mesurada. El abono orgánico es mas un enmendador del suelo y el fertilizante químico aporta directamente los nutrientes que los cultivos requieren. La pregunta es : de donde sacamos tanto abono orgánico, si la mayor parte se encuentra en los océanos?. Si no fuera por los fertilizantes químicos quizás yo y muchos colegas de mi edad no estriamos aquí y ahora.

Let us also debate on the cumulative effect of organic fertilizers accrued on account of residual effect passed on annually over the years , in addition to changes in native soil fertility...

Macro- and micronutrients in organic fertilizers are usually bound to organic compounds, which makes their release progressive and influenced by the biological activity of soil.

While macronutrients in inorganic fertilizers are more available and more soluble in water. The question I ask: is there in flooding conditions (saturation of the soil with water) the phenomenon of leaching?.

In addition, the application of organic fertilizer in these flood conditions, can promote the fermentation of organic matter by aero-anaerobic microorganisms. The question: what is the effect of fermentation products on the availability of macro- and micronutrients and plant growth?

You can have a look in these publications:

https://www.sciencedirect.com/science/article/pii/B978012370626300020X

http://www.fao.org/docrep/w2598e/w2598e06.htm

Total stock, I believe, is the key issue- organic or inorganic should not be a matter.

I AGREE WITH BISWAS.