Science is a method to gain knowledge, but knowing what to do with it is another matter entirely.

Making bales with 30 percent of global crop residues – the stalks and such left after harvesting – and then sinking the bales into the deep ocean could reduce the build up of global carbon dioxide in the atmosphere by up to 15 percent a year, according to just published calculations. . .

The proposed process would remove only above-ground residue. Strand bases his calculations on using 30 percent of crop residue because that's what agricultural scientists say could sustainably be removed, the rest being needed to maintain carbon in the soil. . .

Strand says he thinks any method for removing excess carbon dioxide must do seven things: move hundreds of megatons of carbon, sequester that carbon for thousands of years, be repeatable for centuries, be something that can be implemented immediately using methods already at hand, not cause unacceptable environmental damage and be economical. He says sequestering crop residue in the deep ocean fits the criteria better than any other proposed solution.

There's a lot more in crop residues than just carbon. It would also waste the plant nutrients in crop residues. It would be mining the soil as well as the atmosphere.

Soil is deficient in carbon now. In some cases this is due to continuous cropping of once carbon rich soil, and in others the soil was carbon poor to begin with. The silliest thing one can do from an agronomic and environmental perspective is to throw a third of it into the ocean.

What is "acceptable environmental damage"? Is any damage acceptable for a mere 15% reduction in yearly emissions?

Biochar is a better solution. It returns the carbon to the soil where it improves the soil, and yields valuable coproducts such as heat, electricity, fuel and fertilizer, which further reduces emissions from fossil sources.

The only requirement from the contrived list of attributes that biochar doesn't meet is "use existing methods". It uses better methods than those that exist. A CHP pyrolysis system does several jobs at once, all of which are being done most often with fossil fuels now.

I think that the problem for scientists is narrow knowledge. That can help them make a discovery, but makes it hard for them to know how to use it effectively. It's nice to know - in an academic trivial pursuit sort of way - that bales of hay dumped into an alluvial fan would be quickly buried in sediment and remain buried for a long time, but why would we want to do that? That's wasteful. We have many other problems besides CO2 in the air. A policy that makes them worse is not a net benefit.