Vol. 51—1997 - NorthEastern Weed Science Society

Waggoner December 24, 1994
135
But, the wor iers still fear that the environmental expense
of intensifi ation to lift yields will fallout onto the very
land spared or Nature.
So, in the e d I must defend: Environmental expense need not
cancel the p of it of sparing land for Nature. Economists
would call e vironmental expense 'externalities',
environmenta ists would call it 'impact' and laymen would
call it 'pol ution'. In other places I have called it
'fallout' bu here use the analogy of expense. (Hereafter I
often abbrev'ate 'environmental expense' to simple
'expense'). complete reckoning must subtract this expense
before reach'ng the bottom line of a profit of land spared
for Nature.
s
.sing bonuses
After buying a computer to save clerical labor, the boss of
Widgets Inc. might be surprised by a bonus of accurate
addition of ustomer's bills. Just so, more tons per hectare
can grant en ironmental bonuses, which should be enumerated
before tally'ng the expenses of lifting yields.
Farmers do s
actually inc
appear on al
and cultivat
land from th
erosion and
Irrigation,
plus its inf
salinity, al
Lining ditch
crop harvest
higher yield
radiation mo
of foliage t
So the canop
humanity has
yields less.
me things per area, and higher yields may
r less expense than low yields. Erosion and silt
lists of expenses. A farmer must clear, till,
for low as well as high yields. So by sparing
plow, higher yields give a bonus of less
ilt.
ts consumption of water from streams or aquifers
astructure of dams and canals plus fallout of
o appears on lists of environmental expenses.
s and trickle irrigation raise the efficiency of
d per water used. Although often overlooked,
also raise efficiency. Because incoming
e or less sets evapotranspiration, all canopies
at shade the ground consume about equal water.
that photosynthesizes more and yields more for
a higher water use efficiency than one that
Lush foliage needs little more pesticide to protect it from
an insect or a disease than does sparse foliage.
Keeping weed
a bumper era
keeping them
More than a
fundamental
that, while
shading and
showed, "Whe
increasingly
from the shade beneath the luxuriant foliage of
actually may require less herbicide than
from the thin shade beneath the sparse foliage.
core of years ago, Knake (1972) demonstrated the
atter, shade stunts foxtail. Now, Fig 5 shows
ielding more, denser maize delivers a bonus of
eakening weeds. And, Valenti and Wicks (1992)
nitrogen was applied, winter wheat became
vigorous, [andJ increased light interception