There are two lawn mowers. The more expensive one can cut three green belts at the same time, therefore it is recommended to get it as fast as you can. After cutting grass you can:
- Collect using a forage wagon;
- Use side-delivery rakes and have the grass put in rows (you can do the same with hay or straw);
- Tedder it (a teddered grass immediately becomes hay);
- Hay can be collected by using a baler which creates bales that are easy to collect.
You can't plant grass on every field. You can only buy meadows, you get one when you start a game. Meadows can also be fertilized after each harvest which increases the amount of grass that you get after next mowing.
Warning - remember to mow your grass regularly. You don't have to collect it immediately after that - a new one will start growing on it and after mowing it the one that was already mowed disappears. This means that if you don't need it you don't have to collect grass after each mowing, you can do it after two mowing.
Gathering - wagon or bales?
Forage wagon: Allows you to gather grass and straw. Hay that is collected by a forage wagon is still grass. It requires a powerful tractor and even then the maximum speed is about 18km/h. Because of that you should use rakes and use individual gathering (you don't have to be very precise) because machines gather a raked line in two (or more) tries - unless you have a big rake or a better (wide) combine. An upgraded forage wagon model is not worth your purchase in the early parts of the game - its only difference is the storage capacity.
Baler: Sadly, this machine won't allow you to gather grass but only hay and straw. There are two machines and the difference between them is the shape of bales, the capacity is the same. The only difference is the price and baler's storage capacity - you can store 10 square bales but only 6 round ones. Whether you want to spend money on those with bigger capacity or not depends on the size of your fields.
What you can do with grass/hay? You can feed them to animals and take it to biogas installation (grass or straw, not hay) in order to get silage. You get a little bit of it (about 5% of what you delivered) right after you unload a trailer when you reach your destination. You also get a small amount of money - a few thousands of dollars. When you fill entire silos you must wait 1,5 hours until it will be emptied - you can check the statistics and see how the process goes. Sadly - when the process is over you don't get a lot of silage. The only thing that happens is that you have an empty silos, without any effects. It is possible that this is a bug (the guide is based on the Android version of the game - ver. 220.127.116.11).