sir,  i face a similar problem in my capsicum experiment. So we analyse whole plant for its nutrient uptake. different plant parts were analyzed separately and summed up. For perennial plants, its difficult to estimate root nutrient content but the value can be appxed to 5-8% of total. after this, keeping in view the use efficiency of fertilizer and the % nutrient content in fertilizer, we calculate the nutrient requirement of capsicum which was different from the recommended one. 

regards

As you said the development of balanced fertilizer recommendation for perenial crops is a complex process. However, as mentioned by Shashi, plant analysis is one of the methods to detect the deficiency of plant nutrients, particularly micro-nutrients. Moreover, periodic soil sampling and analysis may help to identify and correct deficient nutrients. Moreover, the management practices followed may also affect the type and amount of fertilizer applied. That means, in the case of small scale farmers, fruits or coffee plantations are not grown as sole crops. Inter-crops such as legumes are used. Organic fertilizers are used, specially for those grown around  backyards. So, such practices need to be taken in to consideration when fertilizer application is planned.

I agree with comments made by Getachew Agegnehu that soil analysis is the way out. However, combined use of organic manure and inorganic fertilizer materials at recommended rate is indispensable under the complex you explained

Thanks gentlemen for participation and taking the discussion further. Whether you use any method of nutrient constraint diagnosis, I am talking about the fine tuning of the recommended doses of fertilizers ( RDF), if you have to practice it  in whole  block/province . One value of RDF  worked out on a specific soil type of a field and a given weather/climate, can you  expend this RDF to entire of block/province having innumerable number of fields. Under this situation , what kind of changes , a practitioner should bring into the practice to address the soil fertility constraints of varying dimensions from one field to another field.  

Dear Anoop Kumar Srivastava , thanks for posing a practical question. There is an agreement that there will be several variables which are possible to interact in a probable field situation acting and counteracting against each other. There might be physiographical, climatological, crop culture management, crop genetic, nutrient quality and quantity variables. One could apprehend either excess or shortage or exact input which is impossible to quantify. Will it be wise to allow the field physic-chemical-cultural and biological environment to interact and compensate mutually for a sustainable production? For example loss due to contour or slope or drainage may be prevented by immobilization, physical trenches or admixture of high quality and low quality organic matter along with promotion of various functional soil biota associated with simultaneous mineralization and immobilization. We have experimented in several tea gardens in South India and have been successful to find out 8 alternate technologies. Following publications may help to understand the concept.

All the best,

B. K. Senapati

Thanks Dr Senapati for providing some pertinent links of some practical utility. Whats your take on fine tuning the  RDF on the basis of spatial variability in soil fertility within a  given field , so that some rationale use of fertilizers is exercised with concrete purpose.  

Anoop Kumar site specific technique will serve you better and especially on developing more maps for attributes. We did full soil analysis and developed soil amendment programme (feeding the soil), which is always a long term focuss and it paid off interms yield and fertiliser input cost but you have to also focuss on plant wise precision management to get significant results.

Dear Anoop Kumar Srivastava, I hope my answers could be help you.

You should choose the type of product wanting to cultivate. The soil samples are taken systematically. Physical and chemical properties of soil are determined in soil laboratory. Macro and micro element concentrations are measured. Fertilizer recommendations are taken according to the plant need in the same soil. If there are more questions, I will answer.

regards

S. Bagheri

Dear Anoop Kumar Srivastava, I hope my answers could be help you.

You should choose the type of product wanting to cultivate. The soil samples are taken systematically. Physical and chemical properties of soil are determined in soil laboratory. Macro and micro element concentrations are measured. Fertilizer recommendations are taken according to the plant need in the same soil. If there are more questions, I will answer.

regards

S. Bagheri

Interesting answers by Stephen and Sepideh . Both of you are talking on the  same concept  of using site specific nutrient management ( SSNM). In such concept , rationale of nutrient use is to tailor fertilizer application as per spatial variability in soil fertility and as per nutrient demand on specific soil type. In any case, variable rate application of fertilizers is to be brought into practice . That means , RDF is to be fine tuned on the principles of SSNM, do you agree Stephen and Sepideh.

Dear Anoop Kumar Srivastava, As you rightly put it, there are multiple variables that come into play. A long term study may therefore be necessary to be able to take into account most of the variables. I am also in agreement with the suggestions of Getachew Agegnehu.

As a result of various experiments carried out in the field, can be found in the scientific literature graphs and tables for dosing of fertilizers, wich must be know some chemical properties of soil and the desired yield to obtain.

That's true Lacatusu. Thats the reason , we have recently developed soil test -based decision support system for fertilizer recommendation in citrus crop using  soil fertility-based variogram developed after differential nutrient response on grid size basis   , which can be effectively replicated to other perennial crops. But the main point of contention is that ( Hope you will agree with me Lacatusu), to develop an equation of wider applicability in field where some  soil properties  in any chosen field undergo both temporal as well as spatial changes so  quickly.

Yes. I agree with you Mr. Anoop.

Yes. I agree with you Mr. Anoop.

Dear Dr. Srivastava, interesting discussion on the topic raised.I can only give general reply as I have no first hand knowledge of citrus or other tree crops.After developing fertilizer recommendation /adjustment equation /calibration in research station /university ,one has to go for follow up trails and frontline  demonstrations before handing over the  recommendations for implementation in farmers fields.In follow up trails we make necessary adjustment in the recommendations.Irrespective of crop ,plant population, yield level anticipated in an area,soil texture( especially amount of clay), rainfall/irrigation ,organic manure use and availability and economic status of farmers are important factors to be considered in modifying the recommendation.High  plant population ,irrigation and high yield expectation, will increase the dose/rate of fertilizer.If organic manure is available we have to compensate for it.More N application may  be needed in coarse textured soil and more P may be needed in fine textured soil .Of course the nature of clay also matters in case of P and K,if it differs from your experimental site.When we recommend certain level of fertilizer application, farmers resources should permit  the application and the level of yield expected in that domain is also important.After adjusting the recommendation in follow up trails ,we have to demonstrate  the recommendationin farmers fields in good number of frontline demonstrations.

Thanks Dr  Hani and other esteemed colleagues for such a lively discussion . Hani , you are right in a way , but our glaring problem  is that , the quantifiable contribution of microbes in dictating the reduction in plant nutrient requirement, is still just  a guess only. Role of microflora as well as microfauna in soil fertility transformation and its consequent effect on plant nutrition vis-a-vis fruit yield and quality is undeniably proven . In this background , I accept what you opined Dr Hani.

Thanks Dr Rao for very comprehensive response as usual. You are now more than a Fruit Specialist for sure .  I agree that once you have RDF worked out  at experimental field  , you revise it later through demonstration trials including the frontline demonstrations . Finally you come out with any revised dose(s) of RDF . Now it is  the turn of implementing the same to growers field where you do not have control on so many factors ( As highlighted by Dr Senapati ). Under such conditions , how to further adjust the fertilizer doses to suit to every orchards requirement . Or alternatively we need to develop some predictive equation based on soil/leaf test value vis-a-vis fertilizer doses and fruit yield , and then keep on tailoring the fertilizer requirement as per individual orchard .  

Dear Anoop Kumar Srivastava , thanks for posing a practical question.

There is an agreement that there will be several variables which are possible to interact in a probable field situation acting and counteracting against each other. There might be physiographical, climatological, crop culture management, crop genetic, nutrient quality and quantity variables. One could apprehend either excess or shortage or exact input which is impossible to quantify.

Will it be wise to allow the field physic-chemical-cultural and biological environment to interact and compensate mutually for a sustainable production? For example loss due to contour or slope or drainage may be prevented by immobilization, physical trenches or admixture of high quality and low quality organic matter along with promotion of various functional soil biota associated with simultaneous mineralization and immobilization. Entropy must be cared for minimization and for maintenance of a sustainable condition.

We have experimented in several tea gardens in South India and have been successful to find out 8 alternate technologies. There by low entropy elements are vital for stability and sustainability of a complex biological system like an agricultural field. . Following publications may help to understand the concept.

I very much appreciate views of Prof. Hani Antoun and the concept of " Precision agriculture". I would love to know more about this.

Thanks everybody for interactions and deliberations. All the best,

B. K. Senapati

Dr. Srivastava, without complicating the situation , what I can say is our  refined recommendation should match with the resource base of farmers.Our calibration charts/ready rekoners/software should have provision to accommodate  the variability in the farmers resources in terms of money ,manure and irrigation water availability etc.Using the soil test report/ particular sheet of farmer,the i/c soil testing lab or local extension personnel should be able to hand out the recommendations.

Dr Rao thanks again. Now with  this discussion , two very pertinent issues emerge to my mind. These are : To what an extent, so called  RDF defines the optimum nutrient requirement  in soil conditions of so variable nature that the same RDF will undergo vast revision through multi-location demonstration traials/frontline demonstration trials ; and  second in the light of comments of Dr Senapati   and Dr Hani as well , let us allow the implemented RDF to take take its own course of  interaction and consequent stabilization of soil fertility as a  nutrient pool of the soil, plus the use  low entropy material , whose role , I feel perhaps come much later . Let us also be considerate that  growers/farmers do not have so long gestation time with regard to correcting the soil fertility constraints through RDF-based recommendation . I am so much thankful to all my esteemed colleagues for being a part of this wonderful discussion . I still request all of you to be on line whats going on this issue.

RDF is nothing short of a shadow boxing where we are not sure of hitting or getting hit as the medium of crop growth is conditioned by diverse unpredictable yield attributes on which human control does not operate. It is enough if the soil is an ideal living phase with perfect life support system.

Very emotional answer for a  science debate Dr Reddy . But , RDF  we suppose , it addresses the possible soil fertility constraints in totality in a given field , irrespective of so many variables beyond human control. At the same , it is equally difficult to predict the soil-plant-fertilizer-environment interaction to find out  an expected  yield response .  

Thank you Dr. Srivastava. What is happening around the world in respect of RDF, the variability is being unduly exploited purely with a business and commercial interests with utter disregard to the natural resources quality, environment and health of ALL. Spirituality with criminal intentions is spreading like a wild fire only to make quick wealth cashing on sentiments of the people. There is no fruit which is not drenched in chemicals to look externally attractive to the consumers unmindful of health of consumers. Even flowers are not spared from poisonous chemical sprays to improve their shelf life. Bioethics is extinct both in theory and practice and sadly many a scientists are not exceptional to submit to the business and industrial lobbies. Please tell me what to do other than  being emotional thus spoil my mental health.

A very interesting discussion which involved several researchers in the area. Nutrient requirements of should be determined after evaluating the existing fertility level of the soil and the nutrient requirements of the crop to be grown, and setting realistic yield expectations. More fertile areas of fields need less fertilizer, particularly N, than less productive areas of the field because they tend to be higher in organic matter and have higher moisture content.

Nitrogen recommendations for most crops except some legumes are based on the amount of NO3-N in the soil and the yield potential. N-fertilizer recommendations are not adjusted based on method of placement, but they are adjusted for previous crop and depth of sampling. To determine the amount of recommended fertilizer N, subtract the amount of NO3N in the soil as determined by soil test and N-credit from the previous crop, if applicable, from the total amount of available N needed for a particular yield goal and crop. Spring wheat and durum recommendations include economic components. The N credit of preceding crops, crop residues and  C/N ratio should be taken into consideration. Some crop residues have a lower C/N ratio than others, which results in a release of plant-available N through rapid decomposition. For example, studies indicate that N-availability is greater after crops with a lower C/N ratio (sugar beet, alfalfa) and crops with lower mass of residues (soybean, dry bean) with less ability to fix N during decomposition.

For P and K fertilizer recommendations, first, the soil test values of these nutrients should be correlated with their corresponding relative yields to determine their critical values. And the refinement for these nutrients should  be done on the basis of soil test values that are done in some years intervals. Broadcast recommendations of P or K for low and very low soil test values may include buildup P and K rates. When rates are reduced, soil test levels are not increased through time. A long-term P and K strategy should include buildup to medium soil test levels. Maximum yield potential is achieved when the soil test levels are reached. Application of less than maintenance rates can cause a decline in P and K levels through time and an accompanying decline in the yield of most crops. Over all, crop and nutrient type, soil fertility level and yield potential of a particular crop are major concerns when fertilizer recommendation refinement is needed.

thanks Getachew for elaborate response .  That is why i keep saying that RDF is very localized in terms of its utility  , either when applied in a bigger field or an area having number of fields. Moreover , RDF is often recommended at 150% ( Dr Reddy ), fail to understand such kind of recommendation , casting un-necessary  doubt on the utility of the experimentation accrueing RDF. More importantly , RDF is in response to particular soil test value and particular yield target . The moment you set a higher yield target , your RDF will undergo colossal changes , irrespective of soil test value or vice -versa  ( Dr  Getachew ). And rightly said about N-recommendation , N-credits through previous crop must be taken into account . But again , if do not take into account any details about previous crop , N-accredition through other means etc , will it not be reflected in soil test value to act as  a reference point for recommending fertilizer doses for the  next crop.

I think there is some confusion in understanding RDF.  RDF is not general recommendation for whole state or a region of the state.Now we have site specific soil test based recommendations for most of the field crops  using either fertilizer alone or integrated nutrient supply recommendations.They are available in the form of calibration tables and also software form. In some states the fertilizer/integrated recommendations are superimposed on georeferenced  soil fertility maps.One can visit the websites of state Governments or IISS,Bhopal for details .Coromandel International is providing recommendations to  farmers in some districts based on village level  soil fertility maps.

We have now  come  back to square one about RDF .How do we develop package of practices for fertilizer use  for any crop for any region or state ?. How do we   start our fertilizer recommendation , it is based on RDF only ?. Who has done what , is not our objective , and those things , I hardly see at all. The current modus operandi of  fertilizer recommendation fails  to address the soil fertility constraints at the field level. What shall  we do to make fertilizer recommendation more responsive to  soil/climate -based variables , in addition to biological properties ( As highlighted  by Dr Senapati , Dr Reddy , Dr Hani , Dr Radu and many other esteemed colleagues ) . Site specific recommendation is still in a developing stage . The fertilizer recommendation program based on site specific ,  is implemented in how many crops in India ? , and so to say   the same about the  integrated use of water and nutrients . The calibration chart for fertilizer recommendation ( If available for handful village(s) ) also need to be  further calibrated  when moved from one village site to another.Nutrient expert or software -based recommendation is out of  context  where you have so many variables at the  field  level .Let us arrive  at a plausible /practical course of steps to transform fertilizer recommendation practice  more accurate   and  nutrient constraint-responsive practice , suiting  to even field , whether individual  farm level or village level to start with. Let us  not sweep away the whole discussion in one sentence  ,  which otherwise is  so fruitful to all of us  .      

Dr.Srivastava,I appreciate your dream of handing over  recommendation to every farmer in every village suited to his farm conditions and socio-economic situations.Do  you expect it to be done by i/c of a Soil Testing Lab or extension specialist?Do you think he will have sufficient knowledge, devotion and time at his disposal to do the job?Do you also believe that the farmer truly follow the recommendation handed out to him?As on today even 10 % of what knowledge we have in the form of recommendations is implemented and  the follow up action  on implementation of recommendations is not regular.Every body's  pious hope and desire is to reach the farmer but to what extent we can reach is difficult to say.

Lets call upon our  other esteemed colleagues to have their views on this subject

We talk about recommended dose. Practically not happening under field conditions. We need to follow the FLD's precisely and make recommendations. Farmers recommendations and experimental recommendations are totally different. Site specific or farm specific nutrient recommendations to be made for higher factor productivity. 

Dr.Mahapatra, you are quite right.we have to advocate the farmers the recommendations validated through front line demonstrations on a large number of field crops in different states .As we can not reach every farmer field in a  vast country like India for demonstration ,whatever demonstrations we conducted in the different parts of  the country, can be considered as site specific.Also, the recommendations are available  in the form of calibration tables and software in almost all the states as mentioned by me in the previous replies .While recommending fertilizer  or manures to farmers, the local extension specialist or i/c soil testing lab can further modify the recommendation based on the resource base of the farmer or other local conditions.

Ms Reyhaneh, the two points raised by you are very pertinent and relevant to the topic being  discussed.The purpose of demonstrations or frontline demonstrations is to validate the recommendations generated at the experimental stations of Agricultural universities  .Normally researchers report a variation of +_!0% in demonstrations  compared to the experimental station results.To account for variation in soils and climate, the experiments are conducted at  more places ,regional research stations of universities. When validating results we have to conduct good number of demonstrations in farmers fields.These demonstrations may also help to educate the farmers in using soil test based balanced nutrients (manure and fertilizers).The second point ,fine tuning the recommendations  for each farmer or farm is very difficult.As you rightly pointed out we give recommendations based on soil test value of a particular field for normal but some what high yield  achievable  in a  particular area.If the farmer has limitations of irrigation water,availabilty of sufficient manure and money to purchage the fertilizers then the extension worker or incharge of soil testing lab may have to modify the recommendation.To achieve 60% or 80% of the targeted yield, the recommendation may also be proportionately lowered .This has to be adjusted keeping in view the resources with farmer , at the same time balancing nutrients.Now we have recommendations for variable amounts of manures and fertilizers to ahcieve the same yield

I share Dr. Rao's comments. He detailed the steps and procedures to be followed in generating data for soil test-based fertilizer recommendations that are targeted  be adopted by users. During fertilizer field trials and demonstrations the main problem is the inclusion of sufficient trial locations that may represent varied agro-ecologies and soil types. This mainly because of lack of research fund, lab facilities, transport and human power. 

After the research results have been verified under on-farmers' fields condition and recommended, the capacity of producers matter to use the recommendations fully and consistently. Because resource-poor farmers in most developing countries are unable to purchase the required amount of input that should be applied as per the recommendations. Moreover, the recommendations need to be fine-tuned at least every 3 or 5 years based on the nutrient, crop and soil type, the production practice and soil water content. For example, the nature  of P fertilizer in soils is different from N or K fertilizer in soils. To do this, research may not be required but well organized and equipped soil and plant analysis labs are required, which is also the major constraint. This is very important and practical topic, but challenging too.

MsReyhaneh,There  are some progressive farmers who are achieving higher yield than the research farm yields.Also there some ares where farmers are consistently getting higher yields in crops like maize ,cotton and chillies. Those farmers are  using hybrids and good agronomy   .When we are fix yield target for prescribing fertilizers we normally  fix some what higher yield target( high er than farmers yields) but which can be achievable in that area.If we fix exactly as per farmers' yields there will not be any improvement in overall productivity in any area.Now some state Agricultural universities like Tamil Nadu  Agricultural University ,Coimbatore. have come up with their own decision support systems.We expect more and more states will follow the same.

M/sReyhaneh,I think there is some  confusion in understanding.In our  fertilizer prescriptions at least two targets are fixed for each crop keeping in view the achievable yields in a particular area( not exactly the experimental yields)Depending on the resources of the farmers especially irrigation availability one of the targets is chosen and fertilizer is prescribed. If some farmer can not afford the lower prescription  also it can further be lowered by 20% or so.Please visit the website of Indian Institute of Soil Science ,Bhopal and look at the recommendations.The site is http://www.nic.in   After  opening the site, choose AICRPS and again choose STCR .One can see the fertilizer recommendations crop wise for the whole country and also for different states(again crop wise)

I am again providing the site address of  IISS as there is some mistake.

http://www.iiss.nic.in  The rest is o.k. as given previously.

The responses to the original question is leading to the concept of precision agriculture (PA), which is typically used on non-perennials/annual crops. However the same concept can be applied to perennial crops as well, perhaps not necessarily using high-tech equipment as in the case of annual crops. From a simplistic point of view, PA requires three basic "ingredients": soil mapping (which includes soil characterization), soil sampling and analysis (to determine nutrient content and availability) and the amount of output per area, which in the case of a perennial crop (i.e., tree crops), it can be the amount of output per tree, but it could also be per area. The amount of output per area or tree, will give us a good proxy or indication of the amount of nutrients that are being taken out of the ecosystem (which can typically be found in the literature, otherwise it will be necessary to analyze the product to determine the amount of nutrient extracted per unit of output) and therefore there is a need to replenish them for the following crop season.

With this information, we can determine the amount of fertilizer (organic, inorganic or a combination of both) to apply for nutrients to be replenished per tree or per area, after every harvest. Considering the climatic and other conditions, it is expected the soil structure and other characteristics to change overtime, therefore there is a need to perform soil analysis at least every two years (if not annually, considering the cost) and do a remapping of the soil perhaps every ten or more years, depending if we notice some changes in the soil structure.

In a summary, the main factor to consider in arriving to the RDF in perennial fruit crops, is first and foremost the amount of output, then based on frequent soil analysis to determine the ready availability for he extracted nutrients in the soil for the next crop season and also based on soil mapping. The same concept is applicable whether we are talking of a plot in an individual farm, or region or province.