Dr Srivastava it is very good question. Optimizing crop response for nutrient application is the most complex exercise where the requirements of the crop have to be matched with the merits and demerits of the soil. 

 when  different crops are grown on the same soil type, fertilizer  may be changed with respect to the crop 2, it is known that changing the crop grown in certain piece of land may have +ve effect in soil fertility  

* Do you feel, soil test/plant analysis -based crop response is still the only  diagnostic basis of such crop behavior?

 for me yes, but can we think about computer program containing data of any single crop nutritional requirements then you can feed the computer with your soil analysis, to give you appropriate crop to be grown or the nutrient modification for the required crop 

 I am not agronomist  

However 

better to use natural fertilizers and minimize chemical to be added to soil   

Agree 

thank you for invitation 

 my best regards 

 SAIF

Sir,

You have placed a good topic in this platform..And too this area to be revisited by scientific colleagues. Mainly we are conducting a STCR or a crop response program for major nutrients like NPK only. It must widen by with the addition of S and micronutrients too. Addition of fertilizer only does not change the yield response, it (response) is mediated by plant physiological behaviour like root geometry, nutrient transporters, microbial transformations of applied fertilisers, nutrient movement within the soil, soil properties and etc. Crop requirements must be prefixed or predetermined before conducting of response program.

Thanks Dr Abdelrahim. Yes , I do agree , when different crops are grown on same soil , the fertilizer recommendation will never remain the same. We need a robust calibration modelling based on results of STCR , and alter superimposition of crop requirement to derive much value added benefits.

Thats a very good point Dr Rajendran . STCR concept is the root of any fertilizer recommendation , but how effectively , we are able translate this information into farmers eccentric knowledge with regard to fertilizer recommendation . Rightly  said , such information needs further elaboration encompassing micronutrients as well. But , there is hardly any effort to define crop requirement nutritionally ?

but now u can add nutrients in the soil with the help of fertilisers and even crop combination of proper crop to increase level of nutrients is also useful 

But , there is hardly any effort to define crop requirement nutritionally ?

For N = leaf colour chart is available now. For the rest of the nutrients is not available. Periodical tissue analysis during crop growth will reveal the nutrient requirement of the crop (impractical to do).

Why do not we think in an other way?.  A crop which is highly efficient under minimal dose of fertilizer condition may serve as an ideal crop or efficient genotypes for farmers kind. 

Very good question of practical nature and economizing fertilizer application as well as maintaining nutrient status of soil. This is gifted specialty by nature to Dr. Anoop Kumar. Definitely, very important discussion will continue for next few days/weeks.

When different crops are grown in same type of soil, responses are mostly different because net response depends upon not only soil type or crops. This does depend upon climatic factors, varieties of crops, sowing and harvesting times and agronomic factors like plant population, fertilizer type, irrigation practices etc. Any variation of these factors will change the response. That is why always site specific recommendations are always appreciated. Working fertilizer recommendations for geographical localities for crop rotations as whole is the way practiced successfully but even then it will not give you 100% precision.

Modeling concept involving as many factors as possible is coming to help. STRC  have been recommended by Rajandran. Let us hear more from our learned colleagues about  this model or still more. 

Dr Rajendran , unless we define the nutritional requirement of crop , we will continue to chase wild goose . Every nutrient works at cellular and subcellular level , have we ever attempted to define nutrient response at this lowest level , we always evaluate the crop response   at tissue level , organ level or at whole plant level. Do you feel , if a nutrient has to be effective in terms of crop response , it will maintain  nutrient level always higher than any other non-responsive factor at all the critical growth stages of crop?. Do you feel , you can afford to skip nutrient supply at any growth stages of a given crop , perhaps no , then why don't we follow nutrient  accumulation pattern , identify those critical growth stages , and accordingly tailor fertilizer application . Your point is very valid . If a crop is  nutritionally efficient , its conversion factor will be so good that you do not need to fertilize so heavily . And , this is the reason , we always say , maximum yields are not always associated with maximum fertilizer application.

Some good points have been raised by Dr. Anoop Kumar.

Thanks Dr Nazir for kind words and equally impressive response after a very long time . We have been deeply missing your critical comments all these months . Hope , now onwards , we will not miss your valuable responses.

Very rightly expressed Dr Nazir , that time has come to look such recommendations in a farming system mode  than single crop basis. Modelling soil test-based fertilizer recommendation is infac, t the root of the fertilizer  recommendation for any crop,. unfortunately calibration models and their fine tuning at regional or at farm level has been direly missing . Is there any attempt of nutrient budgeting in cropping system mode to have checks and balance of nutrients ?

Highly meaningful link in the whole context of on-going discussion  , which highlights :

•Download Nitrogen Loss Assessment Tool (N-LAT).

•Uganda Fertilizer Optimizer . (*Requires Excel 2007 or later.)

•Hybrid-Maize Model - A computer program for simulating corn growth and yield

•Corn Nitrogen Recommendations Calculator

•Winter Wheat Fertilizer Calculator. Use this calculator in conjunction with Fertilizing Winter Wheat, Extension Circular EC 143 (PDF 889 KB, 10 pages)

•2012 Nebraska P-Index(.xls) Instructions: Nebraska PI Documentation (*.pdf) and Troubleshooting Guide (*.pdf)

•The Value of Manure A simple calculator (*.xlsx) for calculating the value of manure. Corresponds with the NebGuide G1519: Calculating the Value of Manure for Crop Production (*.pdf)

•Whole Farm Nutrient Balance(.xls) Instructions: Estimating a Whole Farm Nutrient Balance EC189 (*.pdf )

•Nutrient Inventory (.xls) Instructions: Manure Nutrient and Land Requirement Estimator EC190(*.pdf)

So much thankful to you Dr Broxmeyer . Myself and our colleagues will surely be benefitted.  I request our friends to kindly  have a browse on the link , carries so useful information .

Very good and highly pertinent publications have been uploaded by Dr. Anoop, we are thankful. This subject matter should be discussed deeply to yield some useful recommendations.

Dr Anoop,

Thanks for providing the opportunity to be part of an important discussion.

Fertilizer recommendation in same soil type should be different for not only crop species, rather we should have it for different varieties of the same crop.

Regarding general fertilizer recommendation my views look absurd and may not be appreciated. Farmers' do regular monitoring for good production. It's not always the appropriate quantity or volume, but timely and efficient management of inputs that gives the best economic benefit, which is one of the main criteria for fertilizer prescription. So, the CARE is more important than precise applications. Can we think of fertilizer recommendation on the basis of soil physical condition (soil type as you mentioned, water retention/movement capacity, drainage and aeration status etc), soil biological environment (SOM, soil micro-flora which has been a topic of discussion in one of your questions, enzyme etc etc) and crop characteristics (root growth behaviour, shoot:root ratio, nutrient partitioning pattern etc)???

Thanks and regards to all.

If different crops are planted in the same soil, the need of fertilization will be change, because the nutrient type and content are quite different in plant growth period and different type. If you want to compare the difference on physiological aspect, chloroplast content, photosynthesis, and so on are needed to measure at different time.

Thanks Dr Borah for nice feedback. Growing different crops on same soil type will warrant different management strategy from nutrition point of view. Do we  practice this in reality?. that's a good point to look into physical parameters. Infact , we do have soil buffering capacity -based fertilizer application , but only stands valid for phosphorous . I do agree , we never take into cognizance about the contribution from microbial load , residual effect of nutrients getting accumulated as result of continuous application of RDF ( We will discuss the whole story of RDF later) etc..etc..This is the reason , we keep saying  soil test/plant tissue test-based fertilizer recommendation should always be on real time basis.   

Thanks Barbara for endorsing .My regards

Thanks Xiaohui for your good response. We frequently practice leaf color chart for recommending  N-fertilizer application , by developing NDVI ( Normalised vegetative index). unfortunately , such indices are  not so valid for other nutrients?

So appreciative of you Dr Singh for the on-going discussion . I do agree to take into account such wholesome behavior of soil . But , our biggest limitation is to develop a working mechanism at the field level. You just imagine , simple soil test-based fertilizer recommendation cropwise is so difficult to practice at field level , moment you incorporate such recommendation expended to other soil properties , where shall we land up ?. We now advocate to consider fertilizer recommendation for cropping sequence in a farming system mode , instead of fertilizer recommendation cropwise.. In this regard , we need to introduce the concept like farm  nutrient budgeting , nutrient inventory at farm level etc.

Dr. Kumar's response to different opinions of scholars is justified, I appreciate.

Thanks Dr Nazir . Few more  points that strike to my mind  , while discussing about optimizing the crop nutrient response. How does plant respond to soil conditions involving multiple nutrient constraints ?.How does a plant under such conditions sense  the priorities of different deficient nutrients?. And finally , how does a plant perform satisfactorily under such trying conditions ?. I will appreciate , if anyone of us can throw some light.

Dr Srivastava, these are very pertinent questions, need to know to practice the optimization in crop nutrient response.

Why can not we leave soil alone as a reservoir for use in emergency and study the leaf analysis and yield nutrient analysis and based on these data and the  target yield pump every nutrient needed which can be assimilated by plant as liquid fertilizer with the help of proper enzyme or in a predigested manner friendly to the species.

You have a point Dr Gonuguntla , but such concepts are more valid in perennial crops. in annual crops , especially in cereals , they are still far from practical utility , except for nitrogen ., using leaf color chart or NDVI etc. I am enclosing a PDfs for further reading in this regard , hope , you will like them.  

Can you throw some more light on liquid fertilizers with enzymes..... as a source of nutrients .

Dear Anoop Kumar Srivatsava Ji,

Thanks for the articles.

I am attaching few documents which may help in understanding our approach.

Please feel free to address us for any further assistance.

Best Regards

VIJAY

[email protected]

Friends , let me toss up few more issues pertaining to the on-going discussion , which has already assumed so much of interesting responses from all of you  : 

* How long,  an optimum  nutrient requirement worked out through multi-location experiments , should be practiced in field without periodical  revalidation ?

* Do you feel revisiting the optimum nutrient requirement in the context of emerging micronutrient and secondary nutrients?

* A fertilizer recommendation to be more effective at small farm level , concept Farm typology has been introduced .How effective is this concept?

Dr Srivastava, you are right, the optimum nutrient requirement once worked out should be checked periodically about its effectiveness. There has to be some provision to revise such recommendation from time to time considering the varies issues of the climate change. I also feel very strongly about the micro-nutrients and secondary nutrients as a part of optimum nutrient requirement.

Thanks Dr Shirgure for your thoughtful response . Lets listen to others , what is their stand about these very issues.

i have seen many good answers from specialist but as far as my view is concerned, every crop have different nutrient requirements. it can be analyzed by different experiment on dozes and also on plant nutrition analysis. My knowledge is not much in this matter but I have learned many things from the discussions.

Thanks prof, for giving me this opportunity to study such valuable discussions.

Yes I also feel, nutrient requirement has to be site specific and subjected to periodical evaluation. Long time application needs to be evaluated for residual and cumulative  effects.

Hussain Ahmad, yes every crop has specific nutrient requirement but you have to address the farming system as a whole because nutrient depletion will be there by two/three crops and enhanced if a legume crop is added into the rotation. 

Dear Anoop Kumar Srivastava,

Optimizing Nutrient Use in Low Fertility Soils of the Tropics.

https://www.ipni.net/ppiweb/bcrops.nsf/$webindex/89101BFE89A0D09852574AA0070B295/$file/BC08-3p19.pdf

Regards, Shafagat

Dear Shafagat , thanks   for  your response. Unfortunately , the link , you provided is not visible . But , no doubt , optimizing the nutrient use in low fertility soils of tropics is the real crunch issue.  Let it be any   soil or agro-climate , diagnosis  of nutrient constraints and their suitable remediation through different approaches hold the major key issues.  

Dr Kumar rightly pointed out that having good crops and maintaing soil fertility in tropic on long term basis is the core issue and we are trying to thrash the problem to reach at good conclusion.

Dr Nazir, what is your opinion about the optimizing nutrient response under different land uses versus different crop sequence?. My next point of query is, can we lean some lesson from the existing practices of optimizing nutrient response in highly productive crop zones vis-a-vis low productive crop zones ?.

Dr. Shirgure, Thank you for taking the discussion to more elaborations. A land use or Land utilization types (LUT) (In FAO Land Evaluation/Capability classification) tells us about suitability of a certain land for a specified land utilization type for example growing of dates, growing of sunflower etc. Different crop sequences/rotations have developed by the farmers themselves without any consideration of modern approached. The famous Rice wheat system of India, Pakistan and many other countries just developed keeping in view of the demands for these cereals by the communities. In some of the localities, this may not be suitable at all to the soil. For example this cropping system is even practiced in sandy soils.

The scientists have to take on ground facts as well. In my opinion, where a crop rotation is practiced and farmers strictly attach to it, it is our duty to ease them and come with the fertilizer recommendations for the cropping system as a whole. However, targets should be short term as well as long term. We should address very good yields as well as maintaining soil fertility on long term basis and hand over the soil to new generation in good conditions. 

Yes, we can learn a lesson from the current practices but merely do not stick to it. Just work for better to better and the goal is never ending. Many scientists have recommended some good models which take into consideration the data on present factors.

Thanks  Dr Nazir for some inspiring content . If you remember , few weeks back , i tossed up question addressing the same issue . Some of the prominently sustainable crop sequences have come without much aid from scientific community , i do agree with you . But , our agronomic  crop modelling based long term studies have given further impetus to sustain such famous crop sequences. And , now the the most burning issue of carbon trading , earning carbon credits etc  ..have come up to add newer dimensions to the on-going studies .

Yes, I remember, we discussed this issue in a greater detail. Yes, carbon trading is a new topic and has to be discussed.

Friends , let me add another part of my question . Whether 4R nutrient stewardship concept could serve as some kind of decision support relating fertilizer use efficiency , or do you feel , there is  still a need to add some Rs ....

Really very informative question Dr Srivastava. In fact we need to develop decision support based on 4R nutrient stewardrship concept. 

Thanks Dr Shirgure for your response. Infact information on 4R is the prerequisite to develop any  crop-based Nutrient Expert. IPNI is the premier agency working on this line , and they have come out with some excellent  Nutrient Experts being cross validated through multi-location field trials. 

Most important is identify the nutrient  constraints using crop specific nutrient diagnostics specific for a given soil using soil analysis complimented by plant part analysis.

Is soil analysis  alone sufficient to arrive crop specific nutrient management practices or is it worthwhile to take into consideration of microflora present in the soil

While soil testing , soil fertility indirectly indicates the soil microbial population. But the next course would be soil analysis complimented by leaf analysis in perennial crops. But in annual crops soil analysis is effective.

Dr Vijayaraghavan  and Dr Deka , we can harvest maximum out of soil at minimum cost , only when we have soil specific crops-based fertilizer prescription , otherwise , we will continue to hit around bush , without any distinctive benefits . We need to follow the simple philosophy , feed  the crop according to soil -based diagnosis. 

Totally right Dr. Kumar! Soil specific crop-based fertilizer applications  only would yield appropriately.

Dr Nazir , i still do not see that kind of popularity with green manure , it deserves, except in the conservation agriculture .  Whats your opinion ....?

Yes, Dr. Kumar you are right that green manure is not so popular among farmers though it should be, keeping in view its importance. The reasons are as under.

1. Easy alternative availability in the form of chemical fertilizers, though these cannot meet all soil requirements

2. Labor involved in growing of green manure and incorporation into the soil

3. Extra requirements of irrigation water and other inputs

4. Fitting well in all the crop rotations

The result of this ignorance is appearing in the form depleted soils with very low OM and fertility and very low productivity. This is a great challenge to conservation agriculture   

Thanks Dr Nazir for a  brilliant response , as usual . Dont you think , we need better intervention of green manure as cover crops than conventionally used green manure as a simple manure ..?

Implementation of 4R is most important friends.. 

Agree with Dr Anoop. We need to evaluate and identify suitable cover crops cum green manure crops. Comparable performance was observed for Indigofera and Tephrosia with Sesbania and Crotolaria in DSR. But, we need further studies including more species to be conclusive.

Yes, Dr. Kumar and Sikha Deka.

I agree with Dr Borah, cover crops hold very good promise with regard to optimize the response of nutrient applications, but it creates very good soil microbial environment.  

Dr Shirgure i agree with you . But,  the most important aspect in such exercise is the kind of nutrient cycling and microbial turnover cycle of  the nutrients ..?

We need to keep an eye on soil biological  properties if we have to harvest maximum benefits of fertilizers and optimize the response.

Yes, Sikha Deka.

Yes , i very much agree with both of you , Dr Deka and Dr Nazir . This is the key issue , since it intricately affects the water -nutrient relation ..?

I agree, the optimization in crop response is not possible unless interaction between irrigation and fertilizer application is considered while optimizing the crop response. 

Endorsing the comments from Dr Shirgure and all other colleagues,  i think , best course to optimise the nutrient response of a crop on a given soil , would be to keep your soil biologically active through a series of practices , we have already debated , so that microbial cycling of nutrients continues to meet the crop nutrient demand plus elevated soil moisture as a function of better soil aggregate stability. 

Yes, I agree with you. We need to superimpose the soil properties, with crop requirement as a function of agro-climate and soil environment as whole. 

I still feel the floor management through organic manure residue addition is a good way to optimise the nutrient response to a crop. 

Optimising nutrient response on a given soil and fro a given crop , we need both , the requirement of soil and  requirement of crop , to be super-imposed over each other, like tailoring the crop requirement according to nature and properties of soil. Good comments Dr Shirgure, 

Thanks Dr Srivastava. Unfortunately soil requirement and crop requirement are seldom matched while applying  land use planning in a given area.  

Please see following publication

https://www.researchgate.net/publication/306092504_Water_Soluble_Fertilizers_in_Horticultural_Crops_-_An_appraisal

Article Water Soluble Fertilizers in Horticultural Crops – An appraisal.

Good response Abhishek. 

This may help you