Customized fertilizer (all in one on the basis of target yield for a specific production environment) developed in few of the fertilizer industries (viz Tata Chemicals) have been developed.

There is a need to develop a simple model for addressing multi-nutrients interact ion (soil test based target yield approach) which could help in nutrients optimization and growth & yield assessment, may be N, P and K dose through model like DSSAT and deciding the dose of other nutrients outside the main body of the crop model. 

Hello. You might enquire about APSIM. It deals with N, organic matter, pH effects quite well. P and K are in there too. 

However, I would discourage you from expecting a general crop growth model to represent responses to micronutrients. There are huge uncertainties with macronutrients such as P. 

Also, as you already know, soil tests are reliable for some nutrients, whereas others are weak. Where I live, we have poor tests for available K. Until that is fixed, the modelling is superfluous.

best wishes

Schnug, E.; Haneklaus, S.: Evaluation of the Relative Significance of Sulfur and Other Essential Mineral Elements in Oilseed Rape, Cereals, and Sugar Beet Production. In: Sulfur: A Missing Link between Soils, Crops, and Nutrition. Jez, J. (Ed.), ASA-CSSA-SSSA, Agronomy Monograph 50, 219-233, 2008.

 I feel we have to join together in addressing this issue, as percent recovery of most of the micro-nutrients is quite low between 2-5% but if we apply as fortified/customized the recovery increases and we are able to check the overapplication, i do not say that we deal micro-nutrients in the main programme of the crop model, but address it outside after getting N P and K optimization like in QUEFTS, or realizing that if we apply that micro-nutrient in fortified/customized form the effectiveness for its uptake enhances five to six times,  the foliar application as appropriate combination is also very promising, I feel the need of quantification / optimization to some extent which should be tried by the modelling group, may be IFDC to take the initiative with the experts from various parts, regards and thanks 

A good question by Dr.Kalra who is also a well known crop modeler.I have not worked in modeling but I will comment based on whatever I gained through learning,It is difficult to use models to find the requirements of micronutrients for inclusion in fortified or customized fertilizers.Most of the micronutrient recommendations are generated from simple fertilizer experiments with a few rates of application.Many times even statistical response models are not used to get right rate of application . For Zn or B application to crops, the lowest rate of fertilizer Zn application is 2.5 kg Zn/ha and for boron is 1 kg B/ha . Fortified fertilizers, irrespective of major nutrient /nutrients source, contain 0.5% Zn or 0.2-0.3%B.To reach the minimum recommended level, at least 500 kg/ha of fortified fertilizer need to be applied which is difficult to achieve. If you increase the level of fortification with micronutrients,again the cost will increase.Another problem is that different farmers apply variable amounts of fertilizers depending on economic resources and also different targets of yield  desired by them.

In general I agree with the comments of Dr.Rabinson.I believe that the whole system of soil test calibration should go for simulation modeling in stead of current statistical modelling.For that a fresh approach need to followed ,not the existing crop model modifications..

Thanks a lot, Dr Subba Rao, I also feel the micro-nutrients address should not be in the main model routine but to be dealt outside. with our experience in customized/fortified fertilizers and keeping in mind the interactions amongst nutrients we have to set the dose (if applied as fortified material or customized fertilizer or individually applied. Persons of your vast experience, and Drs Robinson/Schnug/IFDC and others should think on this aspect to develop a simple DSS which could be linked with DSSAT/INFOCROP/APSIM for nutrients management. Same thing is true for foliar nutrition products too

thanks for your kind reply

regards