In terms of capacity to pay for conservation practices, you seem like you are actually interested in cashflow, roughly equal to operating profit less interest, rent and tax, but adding in depreciation and other non cash expenses.

Land is never depreciated in tax considerations although the improvements are depreciated. There are ways to put a value on the use of land for a growing season, compared to sale of the property or conversion of it to other commercial service. Unfortunately many of the methods result in a different value from year to year and may be unfavorable for farming in many years, unless the calculation takes into account  production that is necessary to service debt on equipment and improvements.

I suggest selecting a method that is fairly stable and oriented to the continuation of farming the land. Decide what the land could be rented for to a different farmer for the growing season, compared to the income expected from farming it yourself with a crop insurance policy and the cost of preparation, planting, treatments, and harvest plus transportation. Second method is to discover what cost you could rent additional land for the season, and apply that same value for your owned land that is not required for servicing debt.

Land that must be farmed to service debt gets a higher value in the calculation based on cost of other ways to service the debt, or dispose of the obligation.

Some clues about the expected results are found in competing farms some of which may be owned or leased by farming corporations. By structuring the capital, it is possible to design a farming situation in which all of the cost including rented or leased land can be written off of taxes.

Some friends who routinely farm inherited land have done their own calculations and decided to have all of the work contracted out to specialist who have their own equipment. Some years they sell the harvested crop and other years they sell the standing crop to a contractor, based on yield and risk calculations.

Other friends may routinely rent out the land they own to another farmer who can pay a higher rent considering the cost is written off of taxes. 

A value may be placed on quality of life in farming owned land with owned equipment, but in many cases this format is financed by additional income acquired off the farm. A sizeable number of long time friends acquired considerable holdings in this way where the farming provided a tax shelter in addition to a continuing investment vehicle.

Extended family connections are an important consideration in valuing land use in farming, without which your model might not show why some farming models succeed and others fail.

Interesting points are given by Dr. Jerry.  

I agree with Dr. Jerry, one thing I also do is is to look at the projected years I want to recoup what have been invested in getting the land either rent or purchase from the agro-venture to embacked  

We sometimes use an imputed cost for land, taking the interest on the cost of capital, if we had to buy the land.