Figure 1. Long term annual precipitation received at Bird City, Kansas
-1
cm y80
70
60
50
40
30
20
10
0
31 935 939 943 947 951 955 959 963 967 971 975 979 983 987 991
9
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Data from NOAA, 1931-1997
Figure 2. Precipitation distribution patterns across Kansas
6
6
5
5
4
4
3
3
2
2
1
1
0
78.7
0
44.2
6
64.3
5
6
6
48.8
4
5
3
4
2
102.1
3
2
5
1
1
4
0
0
3
2
1
0
Data from NOAA, 1931-1997
Note: values are average year precipitation in cm
Infiltration rate mm h-1
Figure 3. Effect of surface residue and water quality on infiltration rates
50
40
covered / low esp
covered / high esp
uncovered / low esp
uncovered / high esp
30
20
10
0
10
20
30
40
Cumulative rainfall, mm
50
Soil Sci Soc Am J 62:1377-1383
Figure 4. Ratio of grain yields for 150% residue versus 100% residue across years
for nitrogen by tillage by cover crop study.
Yield 150%/Yield 100%
1.4
1.3
1.2
1.1
1
0.9
0.8
1984
1986
1988
1990
1992
1994
1996
Year
Power et al., 1998
Figure 5. Stability indices of aggregates in conventional and no-tillage systems
for two soil sampling depths.
Stability Index
1
0 to 5 cm depth
0.8
0.6
0.4
>2000
250-2000
106-250
53-106
<53
Stability Index
1
5 to 15 cm depth
0.8
0.6
0.4
>2000
250-2000
106-250
53-106
aggregate size-classes (um )
SSSAJ 58:777-786 (1994)
<53
NT
CT
> 2000 um aggregates
mineralized C (g kg-1)
Figure 6. Carbon dioxide evolution from aggregates in different tillage systems.
3
2.5
2
1.5
1
0.5
0
NT intact
NT crushed
CT intact
CT crushed
0
5
10
15
20
250 to 2000 um aggregates
mineralized C (g kg-1)
incubation time (days)
4
NT intact
3
NT crushed
2
CT intact
1
CT crushed
0
0
SSSAJ 58:787-795 (1994)
5
10
15
incubation time (days)
20
Table 1. Effect of tillage, fertilizer, and cover crop on yield of corn following a
long-term no-tillage study where different amounts of residue were returned to
plots following harvest.
Tillage
without
Fertilizer
without
without
with
with
with
without
without
with
with
LSD (0.10) between
Notes:
Cover crop
Residue additions
---------------- kg / ha ---------------0%
50%
100%
150%
without
61
63
65
80
with
62
69
73
78
without
88
89
89
97
with
87
90
81
88
without
63
66
72
78
with
70
76
74
82
without
90
91
92
98
with
79
88
81
95
previous crop residue amount 5.2 bu
Fertilized with 0 or 67 kg ha-1 ammonium nitrate
Cover crop: hairy vetch overseeded in early September
tillage: none or disk
Power et al., 1998