We are still following very old chemical methods to distinguish the nutrients in soil and water. It consume lot of energy, chemicals, manpower and it also pollute the environment.
Google on water quality sonde, there are some out there, probably not to the extent you would like to see. They are expensive, require calibration from time to time, but potentially useful for some circumstances. Advantage of on site measurements is don't have to preserve samples, worry about keeping cool, etc. Global, Insitu and YSI are a few of the companies. I do not keep fully up to speed on this. My experience likes with most of these mentioned via flame emission and atomic absorptions spectrophy, the old fashioned way. It was time consuming and fortunately at the University of Missouri, Professor Pickett, an expert in these analyses in the 1970s took some time to train me properly how to use his equipment, and when we had the funds, we obtained our own. I carried his work forward by training several students. But I agree with you, progress with sensors based equipment would be helpful as long as those using sensors continue to mix standards, calibrate equipment at proper frequency, use standardized methods of extraction when appropriate, etc.
There is much interest in this field, to my knowledge starting with ion-selective electrodes in the 1960s. Development of devices with selective responses to different chemical species has continued across a wide range of sensing techniques. However, the large intrinsic spatial variation in soil properties has made it difficult to avoid the need to take very many measurements in situ, or obtain a representative sample from the field and take it to a laboratory.
The greatest gains have been with IR spectroscopy, but progress has been slow. The search is on for devices that might be mounted on the front of a tractor and control fertiliser application on the move.
Gaurav you point out a very important question/suggestion. Some development in this regard is very much required.
Thats really a tough ask , there are certain nutrient sensors for in-situ measurement of nutrients like nitrates, phopshates etc , but again laboratory analysis is considered must to have well defined calibration , and most important of all, we need to bring them into solution to analyse them . This is where our major limitation comes , unlike water analysis..This is one of the reasons , why proximal sensing of different nutrients started gaining popularity amongst researchers ...
Here is some more information...
Accurate measurements of soil macronutrients (i.e., nitrogen, phosphorus, and potassium) are needed for efficient agricultural production, including site-specific crop management (SSCM), where fertilizer nutrient application rates are adjusted spatially based on local requirements. Rapid, non-destructive quantification of soil properties, including nutrient levels, has been possible with optical diffuse
reflectance sensing. Another approach, electrochemical sensing based on ion-selective electrodes or ionselective field effect transistors, has been recognized as useful in real-time analysis because of its simplicity, portability, rapid response, and ability to directly measure the analyte with a wide range ofsensitivity. Current sensor developments and related technologies that are applicable to the
measurement of soil macronutrients for SSCM are comprehensively reviewed. Examples of optical andelectrochemical sensors applied in soil analyses are given, while advantages and obstacles to theiradoption are discussed. It is proposed that on-the-go vehicle-based sensing systems have potential forefficiently and rapidly characterizing variability of soil macronutrients within a field. Source : Journal of Environmnetal Engineering .DOI: 10.1039/b906634a..PDF enclosed
Sir,
your question is pertinent to current technology era. Already we have come across all kind of ion selective electrodes (electrochemical principle) but they gave us approximate values rather than accurate values. It may overcome with sensor based modified new entrants. We should learn a lot about solution chemistry to understand the competition between nutrient ions as well as to design a sensor enabled analyser.
Nice response Barbara , these are some issues , in-situ determination will impose some serious interventions , and results will vitiate from the original soil test values..
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