Sir

On farm nutrient supplying resources like cow dung, urine, crop residue, biofertilizers , mycorrhiza , root exudates does have good potential to supply nutrient needs of crops as the this biodiversity is interdependent on each other and no where the resources are lost, but now a days there is a shrinkage of biodiversity and its food web and it is difficult to get even FYM or vermicompost for integrated nutrient management. Hence we will be able to have full use of on farm resources only when we will  have good biodiversity along with its natural food web to recycle the nutrients

Biology isn't mathematics, but we need a bit of numbers. In my opinion, it depends on many factors: 1 - the culture. Different crops need diferent quantities of nutrients. 2 - The composition of the manure in nutrients (at least the macro). 3 - The harvester that you expect. If you provide all the conditions for a high level of production or not. 4 - the biological activy of soil. Soils with low organic matter and/or water disponilibity dont descompose the manure efficiently.

In my point of view, you need to analise the manure, determining the level of nutrients and compare with the necessity of the crop and havest level that you need. If you are in "debt" you need to complement with chemicals. 

I believe on-farm biological resources can meet crop nutrient needs, of course with a great deal of attention to the quality of resources as well as the timing of application. The latter is the most important limiting factor to the effective use of on-farm resources as nutrient release from manure, composts, or green manures is highly dependent on climate and soil microbial capacity. The materials in question can, in my opinion, substantially reduce reliance on external inputs of fertilizers as they have the capacity to enhance soil quality, especially OM content and microbial activity. A soil with high microbial biomass and good microbial functional diversity (due to high OM content) has a higher capacity to enhance nutrient use efficiency, and the nutrients released from the decomposition of the OM can significantly reduce the amounts of external inputs required per unit yield. As to the extent of the contribution, research has shown a lot of variability in time and space depending on the production system. Nevertheless, if not for yields, these organic materials should definitely be included in cropping systems for their positive effects on soil health.

 I compliment colleagues,Araujo,Katanda and Sawicka for their relevant and practical suggestions.The basic purpose is one should not load more chemical fertilizers to soil (to environment).Efficient recycling and recovering nutrients help us in very efficient and economic use of nutrients for sustaining crop productivity but at the same time safeguarding environment (better water and air quality).The first sentences in the replies of Mr.Araujo and Ms.Katada convey the need for a lot of  effort to account for and use the biological inputs in cropping systems.To reduce and rationalize the fertilizer use one needs good and reliable information on other inputs of nutrients.As highlighted by Ms.Sawicka soil contribution need to be first taken care of through good soil testing and interpretation.Once the cropping system is decided, one can work out the total nutrient requirements of crops in rotation/sequence.Then based on the crop  and manure inputs,one can work out the nutrient inputs through manure,Nitrogen fixation by N- fixers can also be estimated from available average figures in literature under field conditions.Weed biomass contribution is difficult to compute(because one may go for hand weeding or chemical weed control) but leaf fall contribution can be worked out from field experiments.Nutrient mobilization /solubilization from organic manure application and root /root exudates also need quantification,though some what difficult.Crop residues recycled as mulch or incorporation contribution need to be worked out.The residues can also be recycled through animal or livestock system as manure or compost.If data can be generated  for 4-5 years one can go for precise nutrient plans or modeling.Ultimately this excise helps us in more intelligent use of fertilizers.

Complements to all the colleagues for useful inputs, and especially to A S Rao sir for very pertinent question. The issue most frequently comes up during interaction with farming community and stakeholders while recommending composting technology (size of the unit to produce targeted compost per year). In present scenario the problem is not volume/quantity of degradable bio-waste (crop residue, weed biomass, animal shed refuge etc) but the availability of appropriate quantity of animal dung. The composting is not efficient in terms of duration and quality of compost without optimum quantity (at least 30 to 40% of the total raw materials) of animal dung due to declining or stagnant cattle and buffalo populations. As per estimates, both from on station and on farm observations, a land holding of 0.25 ha growing three crops a year generates sufficient bio-waste (crop residue, weed biomass, farm litters, bedding materials etc) for recycling into compost that can sustain the productivity of the farm without relying on chemical fertilizers (taking average 15% of the land under non-crop situation). This, however, requires animal dung (say cattle) which can be generated from 10 (6 adult and 4 young) cattle. But, the average livestock in such farm units is less, on an average equal to or little above the half of the required figure. Finally, these figures are not constants, debatable and may vary site to site, situation to situation. Suggestions are welcome.

The question placed by Dr. Suba Rao is of highly practical nature. If we recycle all the biomaterial available at a locality, we can reduce fertilizer application rates and save a lot. However, there are many hurdles to put the concept into practice.

1. The first one is the awareness of the effective recycling technology. The farmers need to be educated of this subject.

2. The quantity available of available of biomaterials is less than the requirements.

3. A decomposition time is always required and gap available in between sowing of crops does not fit the schedule.

4. The machinery to chop the crop residues is costly and cannot be afforded by all farmers.

5. Easy going and laziness of farmers is also a factor.

6. There is a danger of pathogens in using the bio-materials of other than crop residues.

This list is not exhaustive. We need to address these factors by evolving appropriate recipes that are adoptable by the farmers.  

Yes, I agree to Francis, practicing green manuring once in three years is highly useful option.

I appreciate the good responses of Drs. Borah,Nazir and Kirkham. I think we need to discuss one important point raised by Dr.Borah i.e.,the requirement of dung for composting(30-40%) of the material being composted.I have briefly gone through the different methods of composting and their recommended dung or urine requirement.One important point is that all the methods are not demanding equal requirement of dung or urine.The very purpose of adding dung and urine to compost pit/heap is to provide microbial inoculum to facilitate rapid decomposition of organic materials.Now even microbial cultures are available for faster decomposition of organic materials.In Coimbatore method 5-10 kg cow dung  is suspended in 2.5-5.0 liters of of water for sprinkling on one layer.In Indore method urine soaked material along with dung of 15 cm is followed(it was mentioned that old compost also serves as inoculum).In Bangalore method cow dung suspension water is sprinkled over a layer of 25 cm. Of course in all the methods several layers are made up to certain height.So do we need more cow dung for composting?I request colleagues to visit the website of IISS,Bhopal to get familiarity with rapid composting techniques.

Thank you Dr. Rao, your explanation about decomposing dung and urine is OK. Maintaining moisture (not too dry or moist) and stirring and inversion (for aeration) are very important factor to be considered in this regard. 

We are working in this aspect for the last 25 years under arid environment. Our experience is if we can manage sufficient organic decomposed material then it may be possible to reduce nutrient requirement from chemical sources at least by 50-70% depends on the crop. But our recent observation is if we can activate the plant enzyme system by foliar application of biosynthesized nanonutrients along with minimum organic matter application then it may be possible to completely omit most of the major and micro nutrient application from chemical sources. The soil health index also improved tremendously.

Dear Dr.Tarafdar,I appreciate your answer but I have two points to make-one, whether the soil  can supply sufficient amount of nutrients to crop plants(under the influence of activation by nano particles)? Second, without addition of fertilizers and organic materials/manures in substantial amounts,can the soil supply sufficient nutrients  to crops and for how long?I think we need more field experiments for validation.

I agree to the points raised by Dr. Suba Rao. A soil cannot suuply plant nutrients to meet full requirements of crops unless supplemented with manures and fertilizers.

Nazir,the hot composting technique developed by University of California, Berkeley  incorporates many of your and other colleagues suggestions and produces compost in 18 days.The following reference provides complete description of the method and operation on day basis for 18 days.

Hot composting in 18 days

http://deepgreenpermaculture.com/diy-instructions/hot-compost-composting-in-18days/

I do have similar thoughts as those expressed by Rao sir. A decrease in the proportion of cow dung lengthened the composting period. Reducing cow dung from the total waste had been shown to lower pH, increase C:N ratio and decrease bulk density of the compost. This further confirms the slowing down of the composting process due to use of lesser quantity of the cow dung. Another important aspect may be the stability of the compost in terms of storage time. What should be the ideal C:N ratio of compost and how long that compost could be stored for application? Because, the natural process of decomposition would lower the nutrient contents of the compost during storage. Packets (small and big) of compost are seen in go-downs, stores, shops for months. What is the effect on their quality with storage time? Thus, should we revert to more in situ recycling of the waste than relatively expensive composting process? Relatively poor stability of compost was observed (observation trial without replicated data) with decrease in cow dung. Does this really affect and if so is it at structural level? Do we need to look into such aspects? Anticipating more academic explanations from learned and experienced colleagues.

Thanks Rao sir for the link. It's really impressive and interesting. This is the need of the hour, a faster composting method. We eagerly wait to see the technical details like recovery percent, energy requirement, volume of methane produced etc etc per unit compost, and perhaps the most important point of stability of the compost. Thanks

Thank you Dr. Subbarao for making two more points. Yes, for relatively immobile nutrients like P, Zn etc.  where everyday more is accumulating into the soil, there is a possibility to completely omit the chemical fertilizer at the present moment and exploit the native P after making plant more active  by nano-particles  ( say Zn, Mg and P) who are the co-factor of phosphatase enzymes or with the partial help of phosphate solubilizing organisms or phosphatase & phytase producing organisms. In that case whatever the minimum organic input you have that can be incorporate with time to time .But for readily mobile nutrients like N, definitely it will not be possible to completely omit the fertilizer but in that case also if you can activate your plants to release more enzymes up to their potential by hammering with the help of nano-particles which easily enters through the cuticle or stomata and while maving to the cell sap they can trigger different co-factor for release the enzymes up to their potential then also it may be possible to reduce the chemical fertilizer consumtion considerably. Simultaneously with the help of considerable organic inputs you may further reduce the application .

Regarding your second point, I agree that still we do not have sufficient organic matter to maintain total nutrient status in native soil for optimum crop production and more research is needed to see how long the total nutrient status would be maintained without chemical input.

I believe that external fertilizer needs can be reduced substantially by the use of locally available biological inputs. A few important factors here are the organic matter content and the state of decomposition since this will influence the microbe diversity and the availability of nutrients in the form that can be taken up by the plants. We need more field experiments coupled with laboratory studies of microbial efficiency in nutrient recycling, under different conditions, perhaps microcosm experiments may provide a clearer picture.

Some good discussion is going on with addition of knowledge and experience on this topic at the Researchgate website.

Back in 1774 Antoine Lavoisier stated that "Nothing is lost, nothing is created, everything is transformed”. So, if you want to know whether or not locally on-farm available biological inputs can meet the nutrient demands of cropping systems, it is just a matter of calculating the nutrient balance of your cropping system. If the balance is negative, it means that you are depleting your soil and won’t be sustainable in the long run.

For example: if you are producing 6.3 tons of corn per hectare and selling it to the market, it means that your crop has taken up something about 100 kg K/ha. From this 100 kg, about 76 kg can return to the soil with crop residues, but 24 kg will leave you farm. Hence, this 24 kg K will have to be replaced by any means if don’t want to deplete your soil (I am not considering other losses like leaching and surface runoff).

Let’s now consider that you decided to replace the exported together with your soil using manure from some cows you have locally available in your farm.  Considering that the K content in fresh manure is something about 1,24%, you will need to collect apply 1,935 kg of manure to replace only the exported K from your maize field.

Now, to produce the manure you used to apply in your corn field, your cows will have to be fed and let’s say they will be fed in the pasture locally available in your farm. In average, adult bovines excrete about 80% of the nutrients that they intake. So, in order for you to have the 1,935 kg K you need for your corn field, your cows will need to intake 2420 kg of K from your pasture.  So, if you want to replace the 1,935 kg K exported from your corn field with locally produced manure you will have to transfer these 1935g kg out of 2420 kg K taken up from your pasture. The area of your pasture in order to capture the wet and dry K deposition (yearly bioavailability of K through soil formation is so low that is usually not considered in nutrient balances) will have to be something like 2820 ha of pasture because, in average, K atmospheric deposition is 0.858 kg K/ha.

So, considering only K, in order to meet the requirements of 1 hectare of low/medium yield corn (6.3 t/ha) with locally on-farm produced manure, you need to have about 3 thousand hectares of pasture.

Going back to Lavoisier, the only way to meet the nutrient requirements of cropping systems only with locally on-farm inputs is to close the nutrient cycling inside your farm. Zero export.

Note only that for Nitrogen is somewhat different due to BNF.

 Mr.Barros,your comments with good example and illustration are interesting.However there is a little confusion in paragraph 4(probably in units of manure/pasture) and conclusion in paragraph 5.For P or N we have to tap many sources , compared to K.Three points raised by Dr.Borah  are pertinent ,important and need discussion.The three key points are slow composting, less stability of composts and storage quality of composts in low dung amended composts .Dr.Anil Kumar raised the additional issues of manure decomposability in soil and use of herbs for pest and diseases control,Dr.Ms.Rastogi 's comments are also pertinent and the last four lines of  her reply deserve attention of researchers.

.Dr.Tarafdar has explained well the two points raised by me  earlier.What I understand from his explanation is that the nano-particle aided stimulation or triggering of plant enzyme systems and soil enzymes and accelerated uptake of P  and Zn can occur in soils already endowed with adequate or high P and Zn.Those may be areas which received high amounts of P and Zn fertilizers or heavy rates of manure application in previous years.In other soils, the native soil nutrients can get depleted under accelerated uptake by nano-particle stimulation of plant or soil enzyme systems.

Indeed. Please change the 1935 kg K for 1935 kg Manure and the 2420 kg K for 2420 kg pasture in the text. Otherwise the calculations remais the same in my line of thought.

thank you.

Thank you Mr. Barros for your prompt response.One point is not clear to me-why one need 3 thousand hectares of pasture ( 5th paragraph ) to produce 2420 kg pasture(fodder)?

Dr.Borah has raised the issues of slow decomposition possibly because of high C:N ratio,compost stability and quality deterioration in storage.Animal dung may provide the microbial culture and can also lower C:N ratio for faster decomposition organic material.Microbial culture- we can provide through dung,externally brought culture or previously prepared compost.If there is a scarcity of animal dung  for lowering the C:N ratio of the organic material being composted,one can supplement legume straw,fertilizer N source say urea or any other locally available N rich organic material.The stability of compost-well matured compost ( humified ) which has undergone cooling and maturation stages may be quite stable and may not deteriorate with time.As I understand the incomplete composting and improper moisture in the packages may also deteriorate the compost quality.This needs proper standardization.

The hot composting method is aerobic method which may not generate methane.One can try to standardize the method under Indian conditiondsas it takes only 18 days  instead of of 60 days to 90 days usually taken by other efficient methods.

Thanks Dr Barros sir and Dr Rao sir for your inputs. Regarding use of cow dung in composting the points mentioned by Rao sir need to be standardized. Is it only C:N ratio or some other role played by cow dung during composting and storage period. The production of methane during hot composting (Berkeley method) has been mentioned. We have taken up to evaluate the hot composting under Assam (India) condition and try to standardize it.

Dr.Borah thank you for your valuable inputs.It is to some extent easy to compute the nutrients supplied by fertilizers, amendments ,organic manures ,green manures and crop residues.We have also some data base of the extent or quantity of N fixed by  N fixers.The problem is quantification of nutrients ,both macro and micro,mobilized in rhizosphere of different crops by the participation of root systems,root exudates and soil microorganisms.Colleagues,is there any data compiled on possible quantities of different nutrients mobilized in rhizosphere of crop plants under different soil -crop -climatic conditions for use in nutrient budgeting?

Mr. Annangi, in the hurry for writng my answer I made a mistake when converting both mg into kg and m2 into ha. The correct ratio values (according to the calculations) would be 30 ha and not 3 thousand ha. I apologize for that.

At the end, the final idea of my answer is that only a nutrient balance can answer to you whether or not locally available on-farm inputs can meet the nutrient demands of your cropping systems. If you are selling products from your farm, the amounts of nutrients that are being exported together with your products usually surpass a lot the amount of nutrients that nauture can provide to you in the same scale of time and space.

D.Barros, I agree with your comment .

Some orientations from my side: 1) Before the invention / arrival of mineral / artificial / Haber-Bosch-based fertilizers, farms in Europe and elsewhere had a smart and self-evident and self-reliance- strategy to use all organic material of a farm and evolving on a farm for recyling, mainly in soil-fertilty-targets. Together with crop-rotation a rather safe and eco-friendly cropping-system developed, however with little innovative further movements and perfections on large scale. 2) Looking back into these old traditional techniques from today's knowledge and experiences a clever approach and strategy has been developed in the organic-agriculture, which provides almost all nutrients and other soil-fertility-inputs required for satisfactory yields. 3) Regular soil-analyses and observations on plants will reveal eventual deficits, which can mostly easily be covered by on-farm-improvements or use of mostly cheaply available organic residues from industrial units, communal sources, other farmers, bio-gas-units, etc. 4) The enormous potentials of a. intercropping, b. catch-cropping, c. alley-cropping, d. mixed-cropping, e. multi-storey-cropping. f. vertical cropping. g. etc. should become more aware among planners, esp. in the tropical permanent cropping-systems (provided rain or irrigation is available). 5) The example of Pennisetum purpureum and its world-record-high production potential in terms of DM as well as nutrient-mobilization from deeper soil-layers opens up a wide horizon of options (mulching, erosion-control, bio-diversity). 6) Keep in mind: nitrogen-fertilizer is free of charge in the air you are breathing....some 80%....and creation has provided the billions of "nitrogen-fertilizer-factories" in terms of leguminous crops. I am amazed how pulse-breeding & cropping is gaining momentum in the German rather agro-chemical-based agriculture. 7. Do not give up the postulate expressed in your question: a clever smart farm-management can achieve almost perfect nutrient-cycles.

Very comprehensive answer has been uploaded by Dr. Biesen, I agree to it.

I believe that, eventhough organic fertilizer take long period of time to release its nutrients to the soil, it is very important in biulding soil structure, improve soil water holding capacity, adding the depleted nutrients to the soil and so on. When we compare it with the inorganic fertilizer, organic fertilizers are very important in correcting soil acidity or alkalinity if  decomposed with the correct ratio of carbon to nitrogen while composting of organic raw materials. Example, compost. Using compost is very necessary than using cow dung lonely or other raw organic matter.

 I join with Dr.Nazir in complimenting Dr.Biesen for his very elaborate and comprehensive answer/comment.Apart from organic  nutrient sources ,the manipulation and appropriate use of cropping system and leguminous crops play great role in efficient nutrient management under irrigated or assured rainfall conditions.It is interesting to note that the pulse breeding and cropping are gaining momentum in Germany to usefully exploit natural N fixing system.

Dear Subbarao

As per my experience and review of the study conducted else where in India reveals that the bio fertilizers can substitute 25 to 30 % of N and P.

I carried out an experiment continuously for seven cycle in soybean and miaze cropping system on permanent large plot size ( 2000 m2). You can substitute 100% of fertilizer requirement of crop thorugh applicaiton of FYM (25t /ha) , Green manure (5 t/ha) and vermicompost (5 t/ha) along with bio fertilizers (5 kg each). The organic farmers in Karnatatak are also adopted liquid organic manures like bheejamrutha, Jeevamrutha, Panchagavya, Bio digester extract and Dhashaparni. they are getting satisfactory yield. some organic farmers are getting better yield than conventional farmers because of soil health maintainane through applicaiton of organics. if you need  any more clarificaitons, pl contact me  you are welcome .

With regards

Chandrashekar cp  

Yes, Pgowda, I agree to your figures of 25-30 % contribution by biofertilizers and organic manures in one season/crop.

 Thank you Dr. Gowda for the in formation provided.In the approach what we have been discussing, the nutrient inputs should be as far as possible from the same field(from the cropping system followed) and on farm resources.Only remaining requirement we have to get from outside as fertilizer input(in organic farming we have to invariably use only organic inputs and some allowed inorganic amendments,not fertilizers).We need quantitative information on contribution of biofertilizers either through nutrient fixation or mobilization.Normally we measure the contribution through increase in soil test values or increased crop uptake.Increase in yield may not give correct picture.

It is better if one works out on farm or farm gate nutrient balance sheet including all possible nutrient inputs like manures(from livestock and poultry),feeds, forages/fodders and grains,fertilizers and other nutrient sources ,legume fixed N, nitrogen and other nutrients in irrigation water.The outputs could be milk and eggs from livestock and poultry,sold grains, feeds,forage/fodders ,manure or compost sold.This balance sheet helps us to know  how efficiently we are managing nutrients and also possible environmental (air water) contamination through over use or misuse .

Dear Mr. Annangi,

regarding the nutrient balance for estamating the potential of on-farm produced inputs to supply cropping systems needs that I mentioned in my previous messages, I would like to add that some year ago, the WAU released a comprehensive tool to estimate Nutrient (N, P and K) and Economic balances at farm scale. It is a very interesting tool because it considers all possible activities within a farm, including cropping systems, livestock, redistribution units (stores, stable, small industry, etc) and even household activities. It calculates inputs (including atmospheric deposition) and outputs, flows between units, balances at the level of each unit as well as at the level of the whole farm. With such tool it is easy to identify: 1 - What is the nutrient balance at the level of your farm?; 2 - which units (primary or secondary production, redistribution, HH, etc) are showing positive or negative balance for each nutrient?; 3 -  when nutrient deficits or excess are taking place. With such an evaluation, it is very easy to develop management strategies for improving nutrient management for the best use of on-farm biological products. It is possible, including, to simulate scenarios.

Dr.Barros,very interesting information for the viewers and followers of this question.Balance sheet may help us to correct ourselves and  go for more efficient and economic and environment friendly nutrient management.How to quantify and bring  in the biological  products in to  nutrient management tools is a big challenge under different agricultural situations.There is also need for  developing such management tools relevant to developing countries.

Dear colleagues,Dr.Borah has raised the issue of nitrogen requirement during composting(through cow dung) and stability of composts during storage or transport.The following papers provide some interesting information on N dynamics during composting and evaluation of compost maturity and stability.

Nitrogen transformation during organic waste composting by the Rutgers system and its effects on pH,EC and maturity of composting mixture. by Sanchez-Monedero,M.A. et al.  Bioresource Technology  78,301-308,2001.(pdf available on line)

Maturity and stability parameters of composts prepared with a wide range of organic wastes .Bernal,M.P. et al.  Bioresource Technology 63,91-99.

www.prairieswine.com/pdf/3268 pdf

Stabilization of organic matter during composting:Influence of process and feedstocks.

Cedric Francou et al. Compost Science an&utilization (200)vol 13,(1)72-83.

http://woodsend.org/pdf-files/s.houout_CSU_Vol13No1.pdf

Good references have been given by Dr. Suba Rao.

To answer to what extent this may depends on the cropping system applied on that farm, the managerial activities done on that farm before, the duration of farming activity done on that farm or soil fertility level, soil type and so on. I think that organic fertilizers or manures amount must be bulky to satisfy the requirement, esp. not on soils ploughed for long period of time even on soils recently plowed. This need would be satisfied through using of different mechanisms like compost application plus adding other organic matters like crop residues,  green manuring, cow dung application and so on. These activities must be done depending soil analysis and cropping system information of the past or the soil history of that area. At the last I would like to say thank you for your nice question!

 Terasa,thank you.You have very nicely summarized the important points of discussion.

Yes Dr. Suba Rao, Terfasa has highlighted the important points. Emphasis should be incorporating all types of crop residues and other available organic matter (better if composted) to maintain organic matter in the soil and soil fertility.

Following