Page:Tree Crops; A Permanent Agriculture (1929).pdf/176

 extensive practice in many parts of Spain and Portugal. It is interesting to compare the yield of the ilex in Algarve with a statement in the Journal of Heredity for September, 1915, to the effect that a certain valley oak tree in California bears a ton of acorns as a full crop. (The average yield of corn per acre in the United States is about 1,400 pounds, or 800 quarts.)

The Portuguese manager of an English-owned estate who had spent his life raising and managing forests (cork mixed with ilex), whose chief products were cork and the pork of acorn-fed pigs, assured me that there were ilex oaks that bore 100 kgms. (220 lbs.), of acorns, 200 (440 lbs.), 300 (660 lbs.), 400 (880 lbs.), but not 500. He further stated that a tract of ilex was fairly constant in its yield although the individual trees usually bore on alternate years."

Mr. John L. Wilson, an Englishman with an engineering education, who is the managing director of the company owning these cork estates, took the trouble to measure the crop of one particular cork tree which had a spread of forty-five feet and which yielded 840 liters of acorns. This amount is sufficient to furnish a pig that weighs a hundred pounds his standard Portuguese ration of seven liters per day for one hundred and twenty days. This should, by Portuguese expectations, increase the weight of the pig to two hundred and thirty pounds, thereby getting one hundred and thirty pounds of live pork by way of one pig from an exceptional cork tree for one season. The tree would be entitled to loaf the next year and would doubtless claim its rights.