For best financial management point of view, good option to hire tractor & trailer if the land size is small and frequency of usage is low.
Recommend to buy a used tractor tractor & a trailer for around 3L + if the land size is around 25 acres as the tractor hire charges would be expensive and the tractor investment can be recovered in 10 years time (assuming 40k estimated tractor hire changes per year).
Worth going for a new tractor & trailer if the land size is around 40 acres and above.
If the usage of trailer is jut few times a year, consider buying only tractor and hire the trailer when required if there is an option.
Above recommendation is for horticulture purpose based on the requirements outlined.
For weeding works you can use a brush cutter, you get many different varieties there but Stihl is a known one, with 2 stroke petrol engine.
For jeevamrut to plants you can use venturi system fully automatic, if you already have drip irrigation, if not, suggest to install drip first on need basis. Slowly turn the whole farm to drip then there are systems where you can use multiple drums full of jeevamrut manifold them together and pump them into the fields through a filtration unit and a venturi system.
If you still want to buy, suggest to check the hiring rates and availability, if it’s on hire basis cheap and availability wise ok, then no need to buy, keep a tab on expenses for the tractor, that will help you get the idea if you really need to buy one, once you decide the buya second hand one or a new one with subsidy.
For harvest transport, use the market guys vehicles or buy a pick up van, tractor + trailer is way too slow, most times you may also need a tempo to accommodate all the crates of veggies or fruits.