Only the part of it that belongs to the employer. Command of climate, irrigation and nutrient management as a discipline is industry knowledge. Command of this company's own crop recipes, calibration protocol and fault library, developed internally and not published, is what the classification is about.
Ask what a competitor's best grower would not know
The useful test is subtractive. Take everything Priya knows and remove whatever an experienced grower at another operation could reasonably be expected to know; whatever remains is the candidate for specialized knowledge. In her case that residue is substantial and concrete: recipes tuned to this company's cultivars and glass, a calibration procedure written in-house after a sensor drift problem, a fault taxonomy that maps symptoms to causes specific to these installations, and the judgement about when to depart from the recipe that only cycles of use produce.
The petition should say that plainly and then support it. Two framings weaken an otherwise good case. The first is seniority as a proxy, where length of service is offered in place of a description of the knowledge itself.
The second is indispensability without content, asserting that operations would suffer without explaining what she knows that nobody else does.