At the moment there are three farming tools meant to improve amount of crop or the time in which it grows.
- Timid Scarecrow
- Basic crop dust
- Basic compost
My suggestion is to add 9 extra tools.
- 3 new Scarecrows, 1 useable starting at lvl 16 (eg. 40% increase), 1 at lvl 32 (eg. 60% increase) and 1 at lvl 48 (eg. 80% increase)
- 3 new crop dust, same as the scarecrow
- 3 new composts, same as the scarecrow
If you read the names, it is already suggested that at some point, better tools were meant to be added later on. After all, why call something 'basic something' if you don't intend to have an 'improved someting'. Furthermore, at several lvls in farming, you get to use an extra plot. However, using current tools, it is nearly impossible to use more than two plots without loosing a lot of crop due to disease. Improved tools would ensure farming would be more efficient and probably more fun as well.
Next, I would like to suggest that crop dust becomes craftable, like the compost. Now you always have to buy it and when finished with the stack, you end up with an empty bottle that is reusable only for water (for which you have a watering can) or for compost (which you can also buy, or craft) and you don't need loads amounts of empty bottles.
My last suggestion for improving farming tools is to look at the code behind crop dust. According to the description of crop dust, using it results in a 50% crop disease reduction. Experience however tells me there might be some reduction in crop disease, but it certainly isn't 50%. Not even a 50% chance of reduction.