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First, let me comment about the feasibility of "mowing" a 10 acre field with an electric tractor. I assume you are talking about pulling a brush hog. A 5 foot diamter brush hog, also called a rotary cutter, requires approximately 22 HP delivered at the PTO (power take off). That implies that the engine would have to be 26 or 27 HP. For a 10 acre pasture, a 4 foot brush hog would probably work, but it would take longer. How long depends on how fast the tractor goes, the dimensions of the field, how many passes are required, how long it takes to turn around at the end of a pass, how many obstacles and/or corners you have to deal with, etc.. The point is that if you have a 25 or 30 HP tractor you can certainly brush-hog a 10 acre field.

Other implements have their own power requirements, but all that any of them will care about is whether the PTO is turning at the proper speed (typically 540 RPM) and with enough power. They don't care where the power comes from. I would recommend that you research standard tractor implements, including the standard PTOs, and the standard Cat I TPH (category I three point hitch).

If you can deliver 35 HP from an electric motor, the tractor will work. So let's take the definition of 1 HP to be the power required to lift 550 lbs 1 foot in 1 second (550 ft•lbs/s). This corresponds to 745.7 watts. Thus, your 35 HP electric motor will require 26,099.5 watts. If you're using 24 volt batteries, they will then need to supply 26,099.5 W / 24 V = 1087.5 amps. Thus, assuming your motors are nearly 100% efficient, two 600A•hr 24V batteries would last about an hour. This, of course, is for one of the motors. If you use two motors, you can expect to drain four batteries an hour. Of course, you don't really need 35 HP to brush hog a 10 acre field, so you might rethink that requirement and redo the math. You will also want to come up with a better estimate of the motors' efficiency.