Terroir is an essential & undeniable part of rhum agricole. The fact that these rhums keep their cane character though the production and aging processes is a huge part of why we're drawn to their unique, earthy flavors. Distilleries pride themselves on cane cultivars, and many of their recipes depend on specific percentages of cane from specified fields or parcels, known for their individual flavors. In recent years, single cane varietal bottlings have become much more common - in the US we know about Rhum Clément's Canne Bleue (although we don't get the re-designed packaging for each yearly batch that the rest of the world does, thanks to the difficulties the TTB creates with this), and Depaz Blue Cane.
Rhum Bologne has a black cane bottling, La Mauny has their Wouj' bottling, which while only for the island market is 100% red cane, Rhum Bielle has their Canne Grise bottling which is only available in 500ml bottles at 59% abv. The edgy new A 1710 distillery on the Simon property (Simon is where HSE & Rhum Clément are made) may not be an AOC Agricole for several reasons (pot still, year round harvesting to name a few), but they have just released two delectable cane-specific bottlings with the cultivar numbers right on the label. One is blue cane and the other red, and they are home runs in the flavor department (if you like your rhum flavors like a fireworks display, which I'll happily admit I do).
But now a handful of distilleries are leveling up with a new, extremely specific way to express terroir - with parcel specific rhums, called parcellaire. Rhum Longueteau has three parcel specific bottlings. They are so specific about the provenance of these rhums that they print a small map of their land plots on the packaging so you can see exactly where each field is. The fields each grow only one cane varietal, and aren't very large (so the bottlings are limited, naturally). The plots are chosen for their varietal, their proximity to the sea (sea air & a higher salt content in the soil directly affects cane flavor) and sunlight hours (sunlight is the #1 factor in the amount of time needed for cane to reach the minimum brix for harvesting). Sélections Parcellaires n°1 & n°9 are made with red cane (R-570). The plot source for n°1 is in full sun and is quite dry, while the plot for n°9 is surrounded by streams and is very humid. Sélection Parcellaire n°4 is made with blue cane (B69-566) and is also grown in a parcel surrounded by water. The resulting bottlings are fantastic, hyper-flavorful, and astonishingly different from each other, truly illustrating the huge effect even minor geographical differences can make. I challenge anyone who insists terroir isn't present in distilled spirits to taste these.
Habitation Saint-Etienne (HSE) has recently picked up the mantle of parcellaire. Their upcoming release Parcellaire # 1, "Canne d'Or" is also made from the R-570 cane, a cultivar created on Réunion Island. Although as far as I know Rhum Longueteau from Guadeloupe is the first to codify parcel-specific bottlings & to use the parcellaire term, it is worth noting that Trois Rivierès (Martinique) may have been the first to embrace the concept. Cuvée de l’Océan is a parcellaire - cane harvested from L’Anse Trabaud, a parcel in the extreme southeast corner of the island practically on top of a magnificent beach. The bottling is put together to maximize the brine qualities the cane grown there exhibits - and bottled to advertise this fact. What I can't speak to specifically is whether the cane in Cuvée de l’Océan is all one cane varietal or not, although I assume they would specify if it were. The AOC specifies which plots of land on Martinique may grow cane, but doesn't define the term parcellaire in terms of product bottlings, as this usage is fairly new. Of course, since Longueteau is on Guadeloupe, the Martinique AOC rules don't apply, making it difficult to compare apples to apples in terms of regulation.
In terms of flavor comparison, however, I encourage you to seek out these apples and compare them for yourself. The beauty of hyper-specific terroir is just another reason to love earthy, salty and vegetal rhum agricole.