Neg. Neps absorb nutrients quite well through their roots (though better through the pitchers). Their soils are usually deficient in essential nutrients, but can be quite high in trace nutrients like magnesium, etc. There are also ultrapotassic ultramafic rocks, which I wouldn't be surprised if neps grew in those, since they are usually found with "normal" ultramafic rock IIRC.plus cps get therte nutrient frominsects not the soil