Agriculture Reference
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10,000
Loess-derived
9000
Till-derived
8000
7000
6000
0
10 20
ickness of a horizon (cm)
30
40
50
FIGURE 17.1 Effect of thickness of the A horizon on corn yields for loess- and till-derived
soils. (Reprinted from Soil Tillage Res , 81, Fenton T.E. et al. Erosional impact on organic
matter content and productivity of selected Iowa soils, 163-171, Copyright 2005, with per-
mission from Elsevier.)
9500
NFERT = 91 kg/ha
9000
NFERT = 45 kg/ha
8500
NFERT= 68 kg/ha
8000
7500
7000
0
10 20
ickness of a horizon (cm)
30
40
50
FIGURE 17.2 Effect of thickness of the A horizon on corn yields for loess- and till-derived
soils combined with 45, 68, and 91 kg/ha of nitrogen fertilizer. (Reprinted from Soil Tillage
Res , 81, Fenton T.E. et al. Erosional impact on organic matter content and productivity of
selected Iowa soils, 163-171, Copyright 2005, with permission from Elsevier.)
The impact of technology on the yield curve must be better understood in relation
to the true cost of lost “potential” production. Evidence suggests ( Fig u r e 17.3 ) that
technology shifts the function to greater yields but in a skewed manner (Walker et al.
1983). There is a greater influence of technology with increasing TSD, or less eroded
soils; yet the greatest need for recovery through technological influence needs to
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