New turf, weed growing?

Hey everybody, I recently destroyed my yard due to weeds and poplar roots growing underneath.
I spread grass seed over a week and a half ago. I put some soil, but not much.

This is what the area looks like:



However, this thing here is starting to pop up and I'm not sure what it is:



I got paranoid, so I grabbed some of the seeds I used and put them in a little pot and germinated them to see what they looked like.
It looks like this:



Not only does it look exactly like grass, but it's also grown in less than 5 days.
My yard has completely bare spots, and it was seeded over a week ago.
That, and whatever is growing does not look like grass.

Any help ID-ing the flora and suggestions to permanently get rid of it if necessary?

Thanks!

 

What you have growing are weed seedlings, the grass hasn`t germinated yet. I don`t think there is much you can do about it at present. Welcome to the site by the way.

 

Thanks!

What do you recommend as next steps? Should I apply herbicide throughout the whole lawn or should I wait for them to grow? These things are beginning to sprout all over.

Kind of confused!

Thanks!

 

The problem is, if you spray them with herbicide and the grass is just germinating, you will kill it all. Are you really in Spain? That is another factor.

 

I am really in Spain. In the mountains of Madrid. I realize this doesn't help make it a sterile environment.

These seedlings are sprouting all over. It'll be impossible to pluck.

I used a spade to pluck out all the previous vegetation, but that's obviously left roots.

My end goal is having wheatgrass cover the area.
What steps do I need to take?

I can't remove the soil. Is there a way to sterilize it?

(PS, Nothing's off the table. I'm willing to destroy my germinating seedlings.)

 

It has to go. Use weedkiller.

 

Supposing I use Round-Up (or another total weed-killer), how long will it be until I can seed? I want my lawn to be freaking perfect!


Thanks!!