What is the pH of the topsoil? and do you fertilize? One thing to note is that pines have a shallow root system, so they can grow over an alkaline bed, but only if the topsoil is quite acidic. They require the acid to pick up certain nutrients, so maintaining that acid topsoil, and fertilizing (because the tree can't access the nutrients from the subsoil, and it's similar to being potted) is key. Your plant seems to be badly affected, but if there's no disease (I'll trust your judgement here), treating the soil o acidify, as well as fertilizing, and topdressing with compost, it can come back. —
J. Musser 50 secs ago