Reduced tillage and crop rotation systems with winter wheat, grain sorghum, corn and soybean. Mark M. Claassen and Kraig L. Roozeboom Kansas State University Department of Agronomy Introduction Winter wheat is a dominant component of cropping systems in the central Great Plains, but row crops have become more common regionally in crop rotations that conserve moisture with reduced tillage or no-tillage (NT). Tillage and cropping systems have been investigated extensively in the west central Great Plains, where cropping systems typically involve one or two crops and a fallow period. In this environment NT systems have increased fallow water storage efficiency (McGee et al., 1997) and grain water use efficiency when combined with greater cropping intensification (Peterson et al., 1996, Farahani et al., 1998). More intensive rotation with summer crops generally has resulted in greater net return than a traditional wheat-fallow system (Dhuyvetter et al. 1996). However, little information is available showing yield responses to tillage and crop rotation in the central region receiving adequate rainfall to allow successful planting of winter wheat immediately after row crop harvest. Objectives This study was conducted over a 10-year period on a Ladysmith silty clay loam (Udertic Argiustoll) to evaluate the effects of tillage on corn, soybean, and grain sorghum production in annual rotation with winter wheat and on monoculture wheat and grain sorghum and compare row-crop wheat rotations with monoculture wheat and grain sorghum. Methods Tillage systems for row crops – corn (C), soybean (S), and grain sorghum (GS) in annual rotation with wheat (W): v-blade (V) and no-till (NT) Tillage systems for continuous wheat (W-W): burn (B), chisel (C), and no-till (NT) Tillage systems for continuous grain sorghum (GS-GS) in early (May) and conventional (June) dates of planting: chisel (C) and no-till (NT) Each system, except no‑till, included secondary tillage with a sweep-treader. Wheat in all rotations was planted no-till after each row-crop harvest. Grain sorghum in GS-W was planted on the same May date as early GS-GS. Results Tables 1, 2, and 4: means followed by the same letter within a column were not significantly different ( = 0.05). Table 3: means followed by the same letter within a column for each crop (C, GS, S) were not significantly different ( = 0.05). Figures: bars with the same letter were not significantly different ( = 0.05). Results (continued) Wheat yield (Table 1, Figure 2) Tillage in alternate years did not consistently affect yield of no-till wheat after row crops. Wheat produced greatest average yields after soybean and corn. Wheat rotated with grain sorghum was comparable to continuous wheat. The burn system increased continuous wheat yields in some years, but decreased production in high-rainfall seasons because of poorer infiltration. Tillage system effect on continuous wheat yield varied with year, showing no significant effect when averaged over 10 years. Residue cover after wheat planting (Table 2, Figure 3) Residue cover was always greater in NT than in other tillage systems. Residue cover in wheat planted after soybean was less than in wheat planted after corn or sorghum. In continuous wheat, the chisel and burn systems significantly reduced residue cover compared to NT. Corn and soybean yield (Table 3, Figure 4) Tillage had little or no effect for either crop. Grain Sorghum yield (Table 3, Figure 5) Grain sorghum after wheat averaged 1.03 Mg ha-1 more than continuous grain sorghum with no tillage effect in either case. Planting date and tillage effects on grain sorghum varied in relation to the incidence of drought stress. On average, neither planting date nor tillage significantly influenced grain sorghum production. Residue cover after row-crop planting (Table 4, Figure 6) Post-planting crop residue cover in corn, grain sorghum and soybean after wheat showed no interaction between row crop and tillage system. Crop residue cover after grain sorghum planting averaged 11% more in NT sorghum after wheat than in NT continuous sorghum. June versus May planting of continuous grain sorghum resulted in 12% less crop residue cover regardless of tillage system. Conclusions In an environment with an annual rainfall of 840 mm, no-till winter wheat can be successfully double-cropped after row crops. Preferred antecedent row crops for winter wheat are soybean > corn > grain sorghum. On slowly permeable soils, complete crop residue destruction by tillage or burning over time may reduce water infiltration rate. Planting grain sorghum early can facilitate rotation to wheat without harming long-term average sorghum yield. Crop rotation tends to impact wheat and grain sorghum yields much more than tillage. Maintenance of >30% crop residue cover between winter wheat harvest and row crop planting the next spring is difficult when tillage is the only method of weed control. References Dhuyvetter, K.C., C.R. Thompson, C.A. Norwood, and A.D. Halvorson. 1996. Economics of dryland cropping systems in the Great Plains: a review. J. Prod. Agric. 9:216-222. Farahani, H.J., G.A. Peterson, D.G. Westfall, L.A. Sherrod, and L.R. Ahuja. 1998. Soil water storage in dryland cropping systems: the significance of cropping intensification. Soil Sci.Soc. Am. J. 62:984-991. McGee E.A, G.A. Peterson, and D.G. Westfall. 1997. Water storage efficiency in no-till dryland cropping systems. J. Soil Water Conserv. 52:131-136. Peterson, G.A., A.J. Schlegel, D.L. Tanaka, and O.R. Jones. 1996. Precipitation use efficiency as affected by cropping and tillage systems. J. Prod. Agric. 9:180-186. Table 1. Annual winter wheat yield, Mg ha-1. Rotation Tillage 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 W-C V-Blade 5.62 ab 3.45 a 2.91 abc 3.22 c 3.26 a 3.30 a 4.01 ab 4.61 ab 3.90 b 4.40 a No-Till 5.99 a 3.01 bc 3.32 a 2.84 cde 3.29 a 3.40 a 4.73 a 4.53 ab 3.69 b 4.13 a W-GS 3.55 e 2.86 c 2.06 cd 2.24 f 2.75 bc 3.74 a 3.96 ab 4.36 b 3.44 bc 4.23 a 2.45 f 2.80 c 2.83 abcd 2.49 ef 2.49 c 3.23 a 4.62 ab 4.42 b 3.45 bc 3.61 a W-S 5.30 bc 3.28 ab 3.05 ab 3.66 b 3.70 a 3.99 ab 3.56 c 4.96 a 4.24 a 5.64 ab 3.41 a 4.35 a 3.20 a 3.33 a 3.98 ab 3.84 c 4.67 a 4.31 a W-W Burn 4.99 c 2.84 c 2.17 bcd 3.16 c 2.58 c 3.91 a 2.51 d 4.48 ab 2.00 d 4.17 a Chisel 5.17 c 0.96 e 2.77 de 2.66 c 3.58 a 2.99 cd 4.52 ab 1.76 d 4.01 a 3.98 d 2.96 bc 1.97 d 2.93 cd 2.47 c 3.09 a 3.80 bc 4.83 a 2.96 c 4.41 a Figure 2. Row crop rotation and tillage effects on 10-year average winter wheat yield. ab a c bc No-till winter wheat after soybean, a preferred crop sequence. W-S No-till Table 2. Annual crop residue after winter wheat planting, % cover. Rotation Tillage 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 W-C V-Blade 67 ab 65 c 64 b 72 c 65 b 74 b 61 bc 76 ab 73 bc No-Till 58 bc 72 ab 71 b 83 ab 85 a 80 a 78 ab 66 b 80 ab 89 a W-GS 48 c 76 a 67 b 66 c 63 b 73 b 54 c 72 b 81 b 74 a 75 bc 84 a 82 a W-S 34 d 46 d 43 d 51 d 21 e 39 d 20 e 58 c 49 d 32 d 67 c 61 b 52 c 57 c 59 c W-W Burn 5 e 2 f 4 e 1 f 6 d 8 f 9 e 4 f 8 e Chisel 17 e 22 e 40 c 35 d 27 d 19 e 68 bc 91 a 86 a 71 ab 73 a 75 ab 92 a Figure 3. Row crop rotation and tillage effects on 10-year average crop residue cover for winter wheat. a a a b b c d e f Table 3. Annual row crop yield, Mg ha-1. Rotation Tillage 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 C-W V-Blade 7.64 a 3.00 a 4.70 a - 2.79 a 2.82 b 2.34 a 8.64 a 5.34 a 4.40 a No-Till 6.42 a 3.26 a 4.35 a 1.95 b 2.98 a 2.37 a 8.48 a 4.63 a 3.90 a GS-W 7.28 a 6.62 ab 5.39 ab 7.23 a 3.46 a 3.65 b 2.72 b 9.85 a 5.10 a 4.19 cd 7.60 a 6.78 a 6.12 a 6.85 a 3.79 a 3.55 b 3.23 a 9.15 a 5.11 a 4.64 bc GS-GS Chisel 5.67 a 6.12 bc 4.52 cd 5.26 b 2.95 b 3.17 b 2.66 b 7.26 b 4.20 b 4.06 de (May) 5.37 a 5.93 c 4.43 d 5.44 b 2.96 b 3.20 b 2.81 b 7.88 b 4.14 b 3.73 de 5.55 a 2.97 d 5.25 bc 2.76 c 3.54 a 4.64 a 2.86 b 5.10 c 3.10 c 4.77 ab (June) 6.29 a 3.09 d 5.06 bcd 3.19 c 3.85 a 4.65 a 2.85 b 5.44 c 3.12 c 5.28 a S-W 3.33 a 1.49 a 2.39 a 1.70 a 0.84 a 1.27 a 0.52 a 3.47 a 2.06 a 2.18 b 3.44 a 1.46 a 2.26 a 1.37 a 0.91 a 1.38 a 0.53 a 3.39 a 1.86 a 2.62 a Figure 4. Tillage effect on 9-year corn and 10-year soybean average yields. a b Figure 5. Crop rotation and planting date main effects on 10-year average grain sorghum yield. a b Rotation Planting Date (GS-GS) Figure 1. Crop year (Oct-Sept) precipitation KSU Hesston Experiment Field 1994-2006. Table 4. Annual residue after row crop planting, % cover. Rotation Tillage 1997 1998 1999 2000 2001 2002 2003 2005 C-W V-Blade 41 d 36 de 36 c 34 e 29 d 45 c 49 c 34 ef No-Till 70 ab 73 ab 86 a 96 a 83 a 76 a 89 a 92 a GS-W 37 d 29 ef 30 cd 27 e 40 cd 59 c 28 fg 75 a 68 b 78 a 90 a 81 b GS-GS Chisel 38 d 22 d 44 d 38 c 39 e (May) 60 c 73 b 67 b 74 b 70 c 31 d 23 f 19 d - 35 d 24 e 15 h (June) 61 bc 57 c 71 b 58 c 61 b 53 c 49 d S-W 36 d 31 def 28 cd 26 e 25 d 33 d 24 g 68 abc 80 b 78 ab 80 a 84 ab 84 b Figure 6. Row crop rotation and tillage effects on 8-year average crop residue cover for row crops. d a de b c f ef Residue after corn planting in V-blade system. Residue after corn planting in no-till system.