Four-Year Summary of the Use of Soil Conductivity as a Measure of Soil and Crop Status - Agricultural Geophysics - page 275

NO CROP CROP

101 NCK

102
103
104
105
106
107
108
109

MN
CN
CP
MP
MP
CN
CP

Soil core sites
Winter cover crop

Soil co
Wi
No cover crop
No crop

NCK
MN
CN
CP

110
201
202
203
204
205
20
20

NCK

MP
MN

206
207

NCK

CN
MN
MP
CP
CP
MP
MN

208
209
210

20
20
21
301

302
303
304
305
306
307
308
309

NCK

CN

NCK

MN
CN
MP
CP
CN
MP
CP
MN

310
401
402
403
404
405
406

NCK

CP
CN
MN

407
408
409
410

NCK

MP

~255 m

fIGURe 19.1 Split-plot design with four replicates of main plot (cover and no-cover) and subplots (manure
and compost applied at either the N or P needs of the silage corn crop, as well as commercial fertilizer). Soil
cores were taken in replicate 2. Treatments are designated: manure at N rate (MN), compost at N rate (CN),
manure at P rate (MP), compost at P rate (CP), and a commercial fertilizer check (NCK); cover (+CC) and no
cover (−CC).

determine NO 3 -N, soil pH, electrical conductivity on 1:1 soil to water extracts, and soil moisture
content. Bulk density measurements and soil moisture were used to determine soil water-filled pore
space (WFPS).

19.3 ReSUltS And dISCUSSIon

19.3.1 ec a M a P s a n d P l of t s

The number of EC a survey maps generated during the growing seasons of 2000, 2001, 2002, and
2003 were 29, 26, 25, and 34, respectively. A representative EC a image of the cornfield is shown
in Figure 19.2 as generated on June 17, 2002 (DOY 168). When the series of images for a growing
season are viewed in sequence, the maps illustrate field dynamics with overall EC a values rising
uniformly with time (images not shown). The image dynamics are more evident in the mean values
extracted from the survey data and illustrated in Figure 19.3.