Influence of No-Tillage on Soil Organic Carbon, Total Soil Nitrogen, and Winter Wheat (Triticum aestivum L.) Grain Yield
Table 3
Treatment means for grain yield, TSN, and SOC and single-degree-of-freedom orthogonal contrasts between CT and NT treatments at E502 (Lahoma), Oklahoma, USA, 2003–2018.
Treatment
Tillage
N rate (kg·ha−1)
Grain yield (kg·ha−1)†
TSN (g·kg−1)‡
SOC (g·kg−1)‡
Treatment means
2
CT
0
1.98
0.79
7.79
3
CT
22.5
2.51
0.82
8.06
4
CT
45
3.03
0.82
7.89
5
CT
67
3.33
0.85
8.47
6
CT
90
3.78
0.80
7.80
7
CT
112
4.06
0.91
8.78
CV (%)
40
13.7
13.9
2
NT
0
1.74
0.85
8.64
3
NT
22.5
2.23
0.89
8.76
4
NT
45
2.54
0.91
9.12
5
NT
67
2.94
0.90
9.41
6
NT
90
3.25
0.94
9.47
7
NT
112
3.39
1.03
9.84
CV (%)
35
23.8
7.6
Contrast value
2
CT2 vs. NT2
0
0.3933
0.3471
0.0120
3
CT3 vs. NT3
22.5
0.3095
0.2469
0.0381
4
CT4 vs. NT4
45
0.0802
0.1545
0.0003
5
CT5 vs. NT5
67
0.1511
0.4287
0.0052
6
CT6 vs. NT6
90
0.0588
0.0269
<0.0001
7
CT7 vs. NT7
112
0.0178
0.0486
0.0017
Average
CT vs. NT
0.0002
0.0006
<0.0001
CV = coefficient of variation; CT = conventional tillage; NT = no-tillage; TSN = total soil nitrogen; SOC = soil organic carbon; †treatment means for grain yield were obtained under CT (2003–2010) and NT (2011–2018); ‡treatment means for TSN and SOC were obtained under CT (2007–2010) and NT (2011–2014).
