DEPENDS UPON THE OBJECTIVE:

KEEPING IN CONSIDERATION, THE WORD 'SUSTAINABLE', INM IS BEST NUTRIENT MANAGEMENT STRATEGY. THE WORD 'PROGRESSIVE YIELD' IMPLIES THE APPLICATION OF CHEMICALS THROUGH SITE SPECIFIC NUTRIENT MANAGEMENT TO MEET THE DEMAND OF INCREASING POPULATION. FOR AN ENVIRONMENTALIST, ORGANIC FARMING  WILL BE THE BEST CHOICE.

A nutrient management strategy said to be effective has to be sustainable , Shashi. Which method of nutrient management is best with respect to quality production of crop  without incurring any potential mining of nutrient reserve of soil , means considering the overall  impact. And any practitioner of nutrient management would surely look at all these , with sustainability of the practice at the top.

Hi, I think, that the most effective, from the point of view of N use efficiency should be any system considering biological N-fixation on the plantation. But, it is doubtful, if it would most effective from economical point of view, although, it depends on prices, or more generally - on the market conditions.

From the point of view of other elements I think that they will be be used more efficiently, if biological activity of soil is assured, to mobilize nutrients from forms considered as unavailable.

And I think, it is necessary to work on site specific nutrient management in any system, even biodynamic, because soil change frequently very much between places even on one field/plantation.

And, we cannot forgot about the water - without assuring optimal water supply it is impossible to fertilize efficiently. It is, actually, the most important.

So I think that these 4 conditions bolded must be fulfilled together to assure efficient use of nutrients by crops. It is possible to do it in different ways and systems.

Any method of nutrient management strategy  in which all these four conditions viz., biological N-fixation, biological activity of soil , site specific nutrient, and optimal water supply are inbuilt.  Can suggest any such effective  nutrient management strategy, Michel . Its so heartening to see , you opening the discussion  on a interesting note.  Shashi , you added yet another objective into it. Great

It is quite complicated to propose such nutrient management strategy, as it depends on the crop (and it's growth stage, of course) on one hand, and on the local environmental conditions on the other hand.  Economic and social conditions are also very important. It can be a subject of various theses, so it is difficult to suggest this in such discussion as here.

For example, what can we do with orange (Citrus sinensis) in a zone with about 1200mm of annual precipitations (wet season between October and May) in montaneuous area (about 1200 meters over sea level) if we have no possibility of irrigation? And rather extensive agriculture, with limited use of inputs.

1. Assure effective water management: i.e. a) increase it's storage in soil by making infiltration rows (sorry, my English is not so good, and terminology I use is not perfect) to prevent water from flowing away; b) reduce evapotranspiration by using mulch (cutting all plants under the trees), especially from the beginning of rain period (beginning of main flowering), to assure, that all water will be at disposal of orange trees...

2. Nitrogen - during dry period, or starting from end of the harvests, we can try to crop leguminuous plants under tree canopy - to promote certain N fixation. However, at the beginning of rain period, we should apply some additional N to the soil (mineral fertilizers, animal dungs...?)

3. Site specific nutrient management by identifying areas of high, medium and low yields (for example, but we can also identfy additional areas with specific problems and areas with outstanding yielding) and treating them in different way, when fertilizing (types and doses of fertilizers)..etc

4. Biological activity- it i difficult to propose something, but the most important it would be to not injure.  So, avoid any substances which have negative effect of biological activity, or use such substances in the way least harmful possible... Assure optimal pH of soil, additions of some organic matter, air-water conditions in soil...

But, if we have possibility of irrigation, it will change a lot...

So, the topic is very complex., because it is easy to write, but more difficult to practice...

Michal,  thanks for interesting piece of information and  extending the discussion further  . Let us take a conventional method of nutrient management using exclusively inorganic fertilizers , when applied to  a bigger field of variable physiography/ fertility level /depth associated varied soil physico-chemical properties.. so on so forth..., you need to apply site specific nutrient management(SSNM)   in order to rationalise the fertilizer use by tailoring it as per production zone ( High , Medium , Low) as the ultimate strategy . But again there are  limitations with SSNM strategy , you need to develop variogram vis-a-vis production zone(s) using geo-spatial tools. The concept of  SSNM is  still opening up scientifically. On the other hand , the concept of INM ( Integrated nutrient management ) integrates these ingradients  soil , crop , microbes more effectively  than the conventional fertilization program . But again , both the concepts revolve  around balanced fertilization only , with former having better precision of 3R( Right time, right dose , and right source) over latter and vice-versa in terms of fertilizer-use-efficiency. Is the size of field/orchard plus socio-economic condition of grower plus resources availability , combined together that decide the methodology of nutrient management concept  , or the eco-physico-bio set up of a field plays a more deciding role?. Shashi raised a pertinent point about the objectivity of fertilization program  pertaining sustainability , profitable yield , ecological sustainability etc,.

Anoop, when speaking about plantation with exclusive use of inorganic fertilizers (is urea organic, or mineral? Chemically it is organic compound, but as soil chemist I think it works as inorganic), I still think, that first of all we must work on water management, and later- on fertilization. In my opinion uit does not make sense to fertilize before assuring the best possible, in particular conditions, water management, it does not imply irrigation. It depends on particular conditions.

When treating about managent zones, I would rather characterize them by water conditions (optimal wetness, frequetly to wet, and ferquently too dry).

THe 3 R strategy seems obvious in every farming system.

I think, that for about 80-90% of farmers socio-economic conditions are more important than ecological (environmental). The farmer wants to have incomes for himself, and his family. He will not take care of environment, if he has no resources for his family. For poor farmer his family is more important, than the environment, and for rich one - money are more important. In case of about 80-90% of people.

Very nice Michal . You have put the entire discussion rolling in a right direction . You know,  the very purpose of floating this question was to reach to an unanimous consensus that,  which of the nutrient management  strategy is more of a wholesome practice with regard to  nutrient- use- efficiency  vis-a-vis  quality production /income of farmer, irrespective of some specific conditions as you highlighted.  What will be the standard practice to a farmer having no resource limitation. A farmer who is full of resources , what course of strategy of nutrient management   , he will choose at his field  from the standpoint of overall development of his field , besides productivity plus quality dictating the  economics.

I endorse the comments of Michal. I feel there is a need to compare the efficacy of the fertigation verses integrated nutrient management with soil application of micro-nutrients and foliar application of the nutrients.  

Abhisek, now nutrient management has crossed to objective of ecological issues, throw some light on these issues.

Very productive feedback Abhishek , as usual you do . Our important concern is , how does various methods of nutrient management address the soil health issue vis-a-vis soil ecology vis-a-vis carbon sequestration in both labile  as well as non-labile pool to eventually play twin roles. the response from Dr Deka is really timely . Thanks Dr Deka  

Thats the saddest part of any nutrient management program , Pierlorenzo. Soil ecology plus necessity of organic carbon , atleast within  minimum level must be maintained. On RG only , i was interacting with Johann Humer from University of Natural Resources and Life Sciences , Vienna. He commented that organic farmers are allowed to use only their own prepared organic manures .  Fertilization either using organic manures or chemical fertilizers  , is allowed until the upper limit of recommendation permissible by law. so that kind of stringent policy is needed ...

Thats the reason Abhishek , most of the researchers worldwide advocate integrated nutrient management  strategy , still far superior over  other methods of nutrient management . However , it remains to be seen , how this method compares with fertigation technology . 

Thanks Abhishek , i wont say much about my work , let other colleagues go through and interact , that will be the best course . 

Dear sir We have to do soil analysis, plant analysis, visual symptoms, and finaly simple experiment to get bitter nitrient management 

What are  the basic parameters that decide the method of nutrient management strategy?

Thanks Dr El-Boray , these are preliminary exercise , we need to undertake to arrive at optimum doses of nutrients , to be applied through a variety of options . the main attempt here is to look at , which nutrient management option is good with respect to what ?

Good point Dr Deka , i think , time has come to evaluate the effectiveness of  different nutrient management options in terms of ecosystem improvements , but again functional role of soil as ecosystem needs to be defined , relevant to crop , soil and soil ecology as well. 

I still consider integrated nutrient management is the best strategy of the nutrient management since it gradually replaces the over use of chemical fertilizers. 

Iam with dr shirgure openion about the importance of integrated nutrient managent 

Thanks Dr El-Boray , no doubt , integrated nutrient management happens to be very sound method of nutrient management , since concept derives best benefits emerging out of organic manures , chemical fertilizers and microbial interactions , carrying three divergent nutrient sources . It also includes use of cover crops and farm residue management .

INM is no doubt very effective but compared to fertigation, I feel fertigation holds some edge over INM in terms of Nutrient use efficiency at lower application rate.

Yes Dr Deka , there is a much stronger and well established  synergy under INM than any other  nutrient management strategy , as fas as long term maintenance of soil fertility is concerned . However , it remains to be seen , to define the modalities of using all the three distinct sources of nutrients. What would be the ideal scheduling of these three nutrient sources , inorganic fertilizers , organic manures and microbial inoculants...?

There are at least 16 essential chemical elements for plant growth. Carbon, hydrogen, and oxygen, obtained in large amounts from air and water, make up the bulk of plant dry matter in the products of photosynthesis, but usually are not included as "nutrient" elements. Nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), boron (B), molybdenum (Mo), and chlorine (Cl) are obtained from the soil and required by all plants. Sodium, silicon, and nickel are essential elements for some plant species and, although not required, have positive or beneficial effects on the growth of other species. Cobalt is essential for nitrogen fixation by legumes. Additional elements, such as selenium and iodine, are not required by plants, but can be important in plant nutrition because they are essential nutrients for humans and other animals that consume plants.

Which is the best method of nutrient management.

Nutrient management consists of several steps:

Testing the soil to determine the nutrient supplying power of the soil,

Determining the recommended amounts of nutrients needed to produce the desired yields,

Accounting for nutrient inputs from other sources, such as legumes,

Analyzing manures, composts, and irrigation water to determine the nutrient content,

Applying manures or composts at recommended rates and based on the critical nutrient (usually either nitrogen or phosphorus),

Applying the additional inorganic nutrients as needed,

Keeping records so evaluations and adjustments can be made, and

Being aware of your surrounding landscape so sensitive areas can be protected.

This process is an important step in building and maintaining soil quality. For more information on developing a nutrient management plan for your area, contact your local NRCS or Cooperative Extension representative.

Which method you reckon best  and why Faiza.

How do you foresee role of nutrient management in restoring any degradation in soil fertility.

i have gone through all of the comments and suggestions and I feel great to see the experts suggestions. I am waiting to see if someone can suggest an effective nutrient management strategy. Dr Anoop may be you can help us and suggest some. thanks

Thanks Hussain for adding another good response in response to  remarks of Dr Deka .  We still feel , integrated nutrient management is still the best option , since it uses the synergies arising from three divergent sources of nutrients like , organic manures , inorganic fertilizers and microbial inoculants. But , this is not always the case , any such strategy , which maintains the soil organic carbon content always enough to keep the soil biologically alive , should be considered as the best nutrient management option . 

Let me add another  response to trigger off further discussion on the subject  . Any strategy of nutrient management  relating ecological approach that uses locally available materials and inorganic fertilizers as a part of integrated soil fertility management is the best strategy . standard technology packages , delivered in a top-down manner , are inappropriate , rather approaches help farmers make decisions based on combination of their own knowledge and research-based options. synergistic soil fertility management packages are being tested that include soil amendment s like organic matter and rock phosphate , and wiser fertilizer applications , aiming  at sustainable and profitable crop production .  Such kind of strategy is always remunerative from economics point of view...

I agree with you Abhishek , if there is cognizant strategy of nutrient management , we need to upscale such well proven nutrient management strategy according agroecological zones or major climate zones or crop zones , so that , such strategy comes in form of a package..? 

I think best method for fertilization of crops is estimation/optimization through predictive models. Its is a little bit complex but high;y efficient. Currently i am working on perennial ryegrass fertilization optimization through mathematical model. 

Very good point Ihtisham , but our distinctive limitation is to have  such robust and dynamic calibration models covering a variety of crops and soil types  . in addition , the availability of such field tested calibration equations in relation to targeted yields . Thirdly , such information needs to be percolated at the end users , which i always find most difficult part . any model that you come out , needs to field tested at multi-locations , then only you will come to know the precision of such models/equations...

What is your opinion about trunk injection needs just 10 to 15 % of conventional method.

Prof Dr Anoop is right, we will have to test it on different locations. well in my view, green manuring, trunk injection are useful and the links which Mr Abhishek has suggested are worth reading.

Good points raised by Dr Deka and  Hussain , worth appreciating . Accodring to excellent work of Shaaban , we require only 10-15% of fertilizers needed to fulfill the fertilizer doses of different fruit crops, compared to conventional recommended doses of fertilizers. Here is a PDF enclosed for further reading , hope it is useful. 

Dear Dr. Srivastava,

In perennial crops, fertigation has been reported to be distinctly superior to the conventional basin method of irrigation coupled with basal or top dressing of fertilisers within the crop perimeter. Fertigation permits improved efficiency of irrigation water and nutrient use and reduces application costs. It improves plant growth and nutrient uptake, and limits nutrient losses. Applying fertilizers through the irrigation system has several advantages like:

()1) Nutrients can be applied at any time during the season and according to plant requirements.

(2) Placement of mobile nutrients such as nitrogen can be regulated in the soil profile by the amount of water applied.

(3) Applied nutrients are readily available for rapid plant uptake.

(4) Nutrients are applied uniformly over the field.

(5) Groundwater contamination is likely to be less since nitrogen may be applied at any given time. It is often applied when crop uptake and utilization are at their maximum.

(6) Crop damage during fertilizer application is minimized.

Thanks Dr Kundu for your response , no doubt , fertigation is a stand alone concept with regard to perennial fruit crops. Our major limitation is executing the fertigation on a large scale is  absence of cropwise  information about the partitioning of both nutrient requirement and irrigation requirement across critical crop phenophases. And , this becomes a more intriguing exercise when shifts in crop phenology is on the cards in lieu of on-going climate change-related  issues..?. We also face the problem of domesticating our conventional straight fertilizers  into fertigation to make it , really a cost -effective technique, otherwise exclusively depending upon water soluble fertilizers will again turn such technology so redundant ..? 

In humid climates where rainfall continues for more than six months scheduling fertigation is a real crisis in perennial crops.

This is a very important question. I think integrated soil fertility and plant nutrient management involving both organic and inorganic fertilizers may ensure balanced nutrient availability and sustainable production. The inclusion of cover crops and intercropping of leguminous crops may contribute to the improvement of soil fertility and additional harvests from the intercrops. The utilization of all the available resources will help improve not only soil fertility but also the retention of soil moisture and soil resilience.

Yes , i do agree with you Dr Getachew . Many practitioners prefers integrated soil fertility management . I remember , earlier , fertigation was suggested by one of our colleagues , Dr Kundu . I do not know , despite role of fertigation so thoroughly established in perennial fruits, still not so popular ..why i do not know . In absence of fertigation,  integrated soil fertility management is practiced, since   ‘Integrated soil-fertility management’ is an ecological approach that uses locally available amendments and inorganic fertilisers in an integrated way. Standard technology packages, delivered in a top-down manner, are inappropriate; rather, approaches must help farmers make decisions based on a combination of their own knowledge and research-based options. ‘Synergistic’ fertility-management packages are being tested that include soil amendments like organic matter and rock phosphate, and wise fertiliser applications, aiming at sustainable and profitable crop production.

Here are some PDFs for fertigation compared with best management practices in crop like citrus and other fruits as well. 

Summarised version :  Microsprinkler irrigation offers excellent flexibility for site-specific management of water and nitrogen inputs for citrus orchards in the southwestern United States. Escalating water costs, declining water availability, and increasing regulation of nitrogen (N) fertilizer use are causing growers to adopt practices to improve water and N use efficiency. ‘Newhall’ navels on ‘Carrizo’ rootstock were planted in Jan. 1997 and an experiment was initiated. This experiment was continued during 1999. The objective of the experiment was to develop appropriate management guidelines for N fertigation of 3-4 year old microsprinkler-irrigated navel orange trees. Treatments were factorial combinations of three N rates (0.15, 0.30, 0.45 lb N tree-1 yr-1) and three fertigation frequencies (3x/year, monthly, weekly). An untreated control was included. Trunk diameter was not responsive to N rate or fertigation frequency. Leaf N in all treatments, even controls, remained above the critical level (2.5%). However, at each N rate leaf N was highest with the weekly fertigation frequency. Nitrate analyses of soil samples indicate that nitrate leaching was highest with the highest N rate and 3x/year fertigation. Frequent fertigation is recommended because it results in higher leaf N and less nitrate leaching.

PDFs enclosed... 

Abhisek, is there any study comparing fertigation with INM in any annual or perennial crop?

Dr Deka , its a very pertinent question . Or if have any study comparing integrated soil fertility management with fertigation ..?.

What are the conditions under which fertigation is to be practiced and what are the conditions under which INM should be practiced ? 

Thanks Abhishek  for  another good feedback. Inafct , many a times , we comprehensively forget the diagnosis of correct soil fertility constraint using a crop -based soil fertility criteria, the most missing link in making soil test-based fertilizer recommendation , a thumping success. this is where , we need to converge our our efforts to develop such crop specific information , and then fine tune such information suiting to regional level and watershed level. Good information , Abhishek..

Well said Barbara. Here is an abstract of an excellent review paper ..PDF enclosed for further reading and onward discussion ..friends...

Combined Application of Biofertilizers and Inorganic Nutrients Improves Sweet Potato Yields

Abstrcat :

Sweet potato [Ipomoea batatas (L) Lam] yields currently stand at 4.5 t ha−1 on

smallholder farms in Uganda, despite the attainable yield (45–48 t ha−1 ) of NASPOT 11 cultivar comparable to the potential yield (45 t ha−1 ) in sub-Saharan Africa (SSA). On-farm field experiments were conducted for two seasons in the Mt Elgon High Farmlands and Lake Victoria Crescent agro-ecological zones in Uganda to determine the potential of biofertilizers, specifically arbuscular mycorrhizal fungi (AMF), to increase sweet potato yields (NASPOT 11 cultivar). Two kinds of biofertilizers were compared to different rates of phosphorus (P) fertilizer when applied with or without nitrogen (N) and potassium (K). The sweet potato response to treatments was variable across sites (soil types) and seasons,and significant tuber yield increase (p < 0.05) was promoted by biofertilizer and NPK treatments during the short-rain season in the Ferralsol. Tuber yields ranged from 12.8 to 20.1 t ha−1 in the Rhodic Nitisol (sandy-clay) compared to 7.6 to 14.9 t ha−1 in the Ferralsol (sandy-loam) during the same season. Root colonization was greater in the short-rain season compared to the long-rain season. Biofertilizers combined with N and K realized higher biomass and tuber yield than biofertilizers alone during the short-rain season indicating the need for starter nutrients for hyphal growth and root colonization of AMF. In this study, N0.25PK (34.6 t ha−1

) and N0.5PK (32.9 t ha−1) resulted in the highest yield during the long and the short-rain season, respectively, but there was still a yield gap of 11.9 and 13.6 t ha−1 for the cultivar. Therefore, a combination of 90 kg N ha−1 and 100 kg K ha−1 with either 15 or 30 kg P ha−1 can increase sweet potato yield from 4.5 to >30 t ha−1 . The results also show that to realize significance of AMF in nutrient depleted soils, starter nutrients should be included. Source  Front. Plant Sci., 13 March 2017 | https://doi.org/10.3389/fpls.2017.00219

Article Nutrient Use Efficiency in Perennial Fruit Crops – A Review