Calvin, as a commercial insurance broker I can tell you that you will create more issues "blending" your Irrigation Consultation biz with the rentals. It would be close to impossible to find 1 insurance carrier willing to competitively price a combined program.
That being said, with 2 rental properties (insurance carrier will base their decision on # of rental units, not locations) you want to first find out if your current insurance carrier will offer a General Liability limit of $2million before adding an umbrella policy. This can be done for $25-$50 a year. If they can't do that, they will be able to give you a price for each million in coverage. The higher the limit, the less it costs for each million.
Replacement Cost, special form is the best. It may not be available if your properties are too old for your insurance carrier. If that is the case, try and find an insurance carrier who can offer it. If by last resort, ACV (Actual Cash Value) is your only option, it is very important to insure to the proper value. If you do not, you may not have enough money from the insurance carrier to get your property back to it's previous state.