The Plaintiff, P.H. Chadbourne & Co., appeals from a judgment of the Superior Court (Oxford County) entered September 28,1981, affirming a decision of the Oxford County Commissioners which decision had denied an abatement of the Plaintiff’s property taxes in the Town of Bethel.
The Plaintiff’s ground for appeal is twofold. First, it contends that the decision of the Oxford County Commissioners is unsupported by the evidence. Second, it contends that the Superior Court erred in holding that the “Chase Law,” 36 M.R.S.A. §§ 563 and 564 (1978), was unconstitutional. Because we find the evidence before the county commissioners was sufficient to support their denial of a tax abatement, it is unnecessary to reach the constitutional issue.
We deny the appeal.
The Plaintiff, which owns forest land which it operates for the production of wood and wood products, applied to the Bethel assessors in 1978 for a tax abatement, requesting assessment under the Chase Law, 36 M.R.S.A. §§ 563 and 564 (1978).2 Following denial of the requested abatement by the town assessors, the Plaintiff appealed to the county commissioners who held an evidentiary hearing on January 13, 1979. At this hearing the Plaintiff presented evidence concerning the amount of tax imposed on the land, the annual monetary yield from the land resulting from timbering operations, the efficiency of the management of the land, and the incentive created by the tax burden to abandon operation of the land for wood production.
The county commissioners concluded that the Plaintiff had failed to meet the burden imposed by the Chase Law of showing that the tax created an incentive to abandon the land. Essentially this was a finding of fact by the commissioners, albeit a negative one. On appeal pursuant to 36 M.R.S.A. § 844 (1978) and M.R.Civ.P. 80B, the Superior Court affirmed the county commissioners’ finding that the Plaintiff had failed to carry its burden of proof.3
The sole issue before us on this appeal is whether there was compliance with the Chase Law. That is strictly an evidentiary question.
*402When county commissioners have denied an abatement, as in this case, and the reviewing court is called upon to determine whether the negative conclusion is supported by substantial evidence on the record as a whole, the standard is: “whether the record contains ‘such relevant evidence as a reasonable mind might accept as adequate to support ... [that] conclusion.’ ” Bruk v. Town of Georgetown, 436 A.2d 894, 898 (Me.1981) (quoting In re Maine Clean Fuels, Inc., 310 A.2d 736, 741 (Me.1973)).
To qualify for an abatement of property tax on forest land under the Chase Law, 36 M.R.S.A. §§ 563 and 564 (1978), a property owner must show, first, that notwithstanding efficient operation of the land, the land’s after tax annual net return is inadequate in the light of the risks involved; and second, that the tax burden creates an incentive to strip or abandon the land or otherwise operate contrary to the public policy declared in the statute. Here the county commissioners found that the Plaintiff had failed to meet that burden of proof. From the evidence presented to the county commissioners, they were not compelled to reach any other conclusion.
Evidence had been presented that P.H. Chadbourne & Co. had considerably higher management costs per acre than the average operator of forest land for sustained timber production. From this evidence, the commissioners could have concluded that the Plaintiff’s land was not managed efficiently. Similarly, the commissioners could have been unpersuaded by the evidence that the tax burden had created an incentive to strip or abandon the land. Last, the commissioners could reasonably have been unpersuaded by the evidence that because of the tax burden, the Plaintiff’s net annual return on the property was inadequate in light of the risks involved. Eligibility for an abatement under the Chase Law required the taxpayer to establish all the above-mentioned elements. If the county commissioners found that Plaintiff had failed to meet its burden of proof on any one of these elements, they were warranted in denying the abatement.
The commissioners did not make express findings of which element or elements the Plaintiff failed to prove. We do not retreat in any respect from our declaration in Gashgai v. Board of Registration in Medicine, 390 A.2d 1080, 1085 (Me.1978), that “it is an indispensable prerequisite to effective judicial review that an agency’s decision set forth the findings of basic facts as well as the conclusions of ultimate fact and conclusions of law derived therefrom.” However, neither before the Superior Court nor on appeal to the Law Court has the Plaintiff sought any relief from the commissioners’ failure to identify which of the several elements of the Plaintiff’s required proof they found unpersuasive; the Plaintiff rather argues that, regardless of what element or elements were involved in the commissioners’ finding of failure of proof, that finding was “devoid of evidentiary support.” In this civil case, in particular, no reason exists for our departing from the customary rule that this Court will not on its own initiative entertain on appeal a non jurisdictional contention that the affected party has not either asserted in the trial court or argued in brief or orally before us. See McNicholas v. York Beach Village Corp., 394 A.2d 264, 267 (Me.1978); Wildes v. Pens Unlimited Co., 389 A.2d 837, 841 n.6 (Me.1978).
In sum, the denial by the county commissioners of the Plaintiff’s application for a tax abatement is supported by the record made before that agency.
The entry is:
Appeal denied.
Judgment affirmed.
. These statutes provide:
§ 563. It is declared to be the public policy of the State, by which all officials of the State and of its municipal subdivisions are to be guided in the performance of their official duties, to encourage by the maintenance of adequate incentive the operation of all forest lands on a sustained yield basis by their owners, and to establish and maintain uniformity in methods of assessment for purposes of taxation according to the productivity of the land, giving due weight in the determination of assessed value to location and public facilities as factors contributing to advantage in operation.
§ 564. An assessment of forest land for purposes of taxation shall be held to be in excess of just value by any court of competent jurisdiction, upon proof by the owner that the tax burden imposed by the assessment creates an incentive to abandon the land, or to strip the land, or otherwise to operate contrary to the public policy declared in section 563. In proof of his contention the owner shall show that by reason of the burden of the tax he is unable by efficient operation of the forest land on a sustained yield basis to obtain an adequate annual net return commensurate with the risk involved.
For the purposes of this section forest land shall be held to include any single tract of land exceeding 25 acres in area under one ownership which is devoted to the growing of trees for the purpose of cutting for commercial use.
. In addition to affirming the county commissioners’ finding that Plaintiff had failed to carry its burden of proof, the Superior Court stated the view that if interpreted as a mandatory method of tax assessment, the Chase Law would violate the just value and apportionate assessment requirements of Article IX, section 8, of the Maine Constitution. We need not, and do not, reach that constitutional issue in deciding this appeal.