One of the advantages of living a fairly long time is that one remembers what things used to be like way back when. Belonging to the leading edge of the post-World War II baby boom and growing up in Los Angeles in the 1950s is a perfect case in point.

My family bought a house in a new subdivision in Norwalk in the early 1950s as the steady encroachment of urbanization pushed out dairies, farm fields and tree orchards.

In fact, the only exposure I had to agriculture before I took this job was the few short years that my cousins and I played in the pasture behind my house throwing cow pies at each other in smelly games of tag. The dairy owner eventually had to bend to the onslaught of civilization and move away — an exodus literally sparked by errant neighborhood teenagers setting his haystacks ablaze while smoking in his lofts.

For those of us who grew up in Southern California in the 1950s we watched the last remaining vestiges of production agriculture forced out of the region as valuable ag land was gobbled up by developers who replaced it with freeways, businesses and homes. As recently as 1960, L.A. led the nation in total farm production. Fact is, there are no orange orchards in Orange County anymore. Today you can drive 100 miles from L.A. to San Diego without seeing any vacant land except that surrounding Camp Pendleton — which brings me to the point of this column — the rapid elimination of California’s valuable farmland.

It just boggles the mind to contemplate the consequences of paving over our nation’s “breadbasket.” In the years ahead, I believe, the entire state will go the way of Los Angeles as California’s population continues to grow by as many as a half-million new residents each year and Central Valley farm fields continue to vanish at an alarming pace.

To back up my concerns I point to Paving Paradise: A New Perspective of California Farmland Conversion, a report released late last year by the American Farmland Trust, written by AFT California Director Edward Thompson, Jr.

The report is bleak: About one-sixth of all land developed since the Gold Rush was lost between 1990 and 2004. That amounts to about a half million acres, nearly two-thirds of it agricultural land, Thompson notes.

Based on findings from the state Department of Farmland Conservation gathered through its monitoring and mapping program, during that 15-year period, an average of about 38,000 acres a year was earmarked for development. Most troubling is that of all the land converted in California, 28 percent was the state’s best farmland – irrigated cropland that is prime, unique and integral for California’s agricultural output.

The 2002 U.S. Census of Agriculture ranks the state’s most productive agriculture counties, in descending order of farm gate value, as Fresno, Tulare, Kern, Monterey, Merced, Stanislaus, San Joaquin, San Diego, Kings, and Imperial.

Thompson notes in his report that in the past 15 years, more than 60 percent of the land developed in the San Joaquin Valley, which accounts for more than half of the state’s overall agricultural output, consisted of high-quality farmland. In five of the eight counties in the valley, 70 percent of the development took place on prime farmland.

Equally troublesome is the fact that much of this converted acreage is being developed inefficiently. Research indicates that urban population densities in California vary, but on average, total about 7.2 persons per acre statewide, not including the Los Angeles basin. This number, however, does not consider ranchette development on very large rural lots. (These are country estates, hobby farms and other rural residential uses on very large lots up to 40 acres.)

A 1990 American Farmland Trust study found that ranchettes in the Central Valley average five acres in size, which, if one assumes three people per household (a good average in this region), would mean that ranchette development efficiency is only 0.6 people per acre – roughly one-tenth the “efficiency” of urban development in the Valley.

Furthermore, in the San Joaquin Valley, according to the most recent AFT report, new development between 1990 and 2004 consumed an acre for only 8.1 people, about 15 percent less efficient than for the state. (Imagine two four-person touch football teams playing on the gridiron in the Rose Bowl and you get an idea of how spread out this is.)

The AFT research warns that unless a different approach to land-use planning and development is adopted, another 2 million acres could be gone by 2050.

“Given its relentless population growth and the apparent inevitability of city-centered growth, the key to saving farmland in California is to develop less land per person,” the report sums up. “It will take a concerted and sustained effort to promote urban infill, to increase residential densities and commercial floor-to-area ratios, to reduce the amount of land devoted to roads and parking lots, and to curb the spread of ranchettes.”

The report offers these three bullet points that must be done to avert disaster:

• Direct growth away from the highest quality farmland toward less productive land.

• Develop land as efficiently as possible so as not to waste what we must convert.

• Avoid rural ranchette development that fuels land speculation and drives up land costs.

Will California consumers who eat the safest food in the world eventually wake up to the realization that the food they eat does not magically appear on store shelves overnight, but has to be planted and grown on fertile ground, carefully nursed with crop protection and fertilizer tools and water, before it can be harvested and processed for transportation to those very store shelves? Will we ever admit the harsh possibility that future generations may be incapable of feeding themselves in this country?

Without appearing totally alarmist and pessimistic, this trend can be reversed, but quick action is needed now as spelled out by the AFT report. Otherwise, our food supply — not unlike the expensive oil we import today — will depend on foreign markets and shame on us if we allow this to happen.