ghost acreage

in his 1965 book "hungry planet" georg borgstrom defines ghost acreage as the amount of acreage outside a nation's borders that is used to grow the food it imports to sustain itself...he also goes into "fish acreage" and the resultant overfishing of the oceans that nations use to augment their food supplies...good stuff to think about but i have another sort of ghost acreage in mind...according to usda figures farmers in the u.s. planted 35,908,000 hectares of corn in 1940...they planted 35,890,000 in 2010...a slight drop in area...those hectares planted in 1940 yielded 56,058,000 metric tons of corn ( again usda figures )...the slightly smaller area planted in 2010 yielded 316,165,000 metric tons of corn...a 563+% increase in yield in seventy years...wow...so what happened...doubtlessly new hybrids and gmo seeds played a direct part in that massive increase...but so did chemical inputs in the form of fertilizers, herbicides, and insecticides, virtually all based on petrochemicals...according to the u n food and agriculture organization the united states uses 9.1 million tons of nitrogen based fertilizer every year ( china uses double that )...all that increase is based on petroleum products and high quality energy....a draw down of non-renewable resources at the heart of the food system...nothing new here and that's what worries me...on to the photos before the weather here knocks out the power...the gamagrass seed head is beginning to flower...still only three terminal spears so far...the grass must be taking a break after last year...chinese yams in the pgp grabbed onto the wheat grass and the rose bush in my back yard...i disentangled the wheat grass...the rose bush is on its own