That is the first lot of forage silage done on the far end of the farm - cut and collected up. Now time for the next job. Slurry spreading to encourage the grass to grow for second crop!
Every cattle farmer has by law to have a slurry tank (those big round tanks you see on farms these days) and into it goes all the washings-out from cattle sheds and milking parlours - so basically a mixture of cattle poo and water. Of course the tank needs regular emptying otherwise it would overflow. Hence the farmer is off today spreading it all day.
Environmental bodies here in the UK do keep a careful eye on what farmers do these days. We all have licences for various things - for example we have a licence to clean out the beck which runs through most of our fields, put the cleanings out on the sides of the beck to build them up (and throw back in any fish the farmer sees as he is carrying out the operation - (we have small trout and bullheads and they are difficult to see) and keep the area tidy. We also have a licence to store an amount of rubble to fill in gateways during the wet Winters when gateways tend to get very muddy.
The weather here is damp and cool today, so for once the farmer is happy - just right for spreading and making that good, healthy smell.