Optimizing Strip-Till and No-Till Systems for Corn

Recent developments in biofuel demand and the rapid adoption of modern transgenic hybrids are changing production systems towards more corn after corn, more intensive tillage, higher plant populations, and ever higher crop residue levels at harvest. Meeting society’s needs for food, feed, and fuel from grain corn, and in the future from corn stover, requires continued refinement of tillage systems to sustain soils and optimize the uniform development of corn plants in all kinds of stressful environments (whether from cool temperatures, drought, nutrient deficiencies, or compaction). The standard chisel plow system used in continuous corn may be the least sustainable of all tillage systems over a 30-year timeframe. Achieving high corn yields with less tillage requires achieving stands with more uniformity in the growth of adjacent corn plants. New developments including precision automatic guidance, strip-till in continuous corn, nutrient banding in no-till and strip-till, and operation timeliness can improve the success rate of these two effective soil conserving systems even when crop rotations involve more corn than a decade ago. Corn Yield Responses to Alternate Tillage Systems on Various Soils: The long-term yield potential of corn with different tillage systems on dark prairie soils of the Corn Belt has been studied intensively for both the typical corn-soybean rotation, as well as for continuous corn, near West Lafayette, IN since 1975 (Table 1). While equipment, cultivars, and seeding rates were changed periodically, tillage treatments were not altered during the 32 years of this continuing experiment. The results in Table 1 suggest that: 1. Corn yields are greater in rotation than in continuous cropping for all tillage systems. The positive response to rotation is greatest for no-till corn (18% higher than for the same tillage system when corn follows corn). The positive response to rotation is least with moldboard plowed corn (just 4% higher). 2. When corn follows soybean, yields with plow and chisel are likely to be about the same. Yields from the ridge system may be slightly better (3%) than plow and chisel, but not as much superior as one would think given the complete avoidance of traffic on the ridges (rooting zones) over this long-term study. No-till corn yields may be slightly reduced (2%) compared to plow and chisel, but the relative yields of no-till are much lower (14% yield reduction compared to moldboard plowing) when corn is grown continuously. Yield reductions with no-till corn are not due to lower plant populations, but to inherently higher plant-to-plant variability (Boomsma and Vyn, 2007a). Tillage, plant populations, random versus controlled wheel traffic, and nutrient management all affect the extent of variability of corn plants within a row during rapid vegetative and early reproductive growth. Table 1. Corn yield response to tillage and rotation, Long-term Tillage Study on a dark prairie silty clay loam soil near West Lafayette, IN, 1975-2006. Tillage Corn/Soybean Continuous Corn Yield Gain for Rotation Bu/ac % of plow yield Bu/ac % of plow yield % Plow 179.7 172.3 4 Chisel 180.0 100 167.7 97 7 Ridge* 184.3 103 169.1 98 9 No-till 175.2 97 148.3 86 18 * Since 1980 # Data from T.D. West and T.J. Vyn Figure 1. Corn yield response to tillage in a corn-soybean (CS) rotation versus continuous corn (CC) over 32 years versus the last 10 years on a dark prairie silty clay loam soil near West Lafayette, IN. (1975-2006 on left versus 1997-2006 on right). 100 120 140 160 180 200 220 C-S CC C-S CC Plow Chisel No-Till The degree of yield advantage for corn in rotation in the last 10 years is slightly less in the moldboard and chisel systems now compared to the overall 32 year history of this experiment (Figure 1). The rotation advantage was 3% for plow, and 5% for chisel from 1997 to 2006, versus 4% for plow and 7% for chisel from 1975 to 2006. The yield advantage for rotation in no-till corn has remained constant at about 18%. Strip-till corn after corn has yielded equal to chisel plowing even when corn follows corn at our location in Northern Indiana (Table 2). This 11 bushel per acre yield advantage for strip-till versus no-till in continuous corn is significant, and it illustrates the potential of the strip-till system even when corn yields are close to 200 bushels per acre. No-till corn seems to be a superior option when corn follows soybean; because yields are only 2% lower with no-till, farm profit would likely be highest with no-till on soils like these. Table 2. Corn Yield Response to Tillage and Rotation, Long-term Tillage Study on Sebawa loam soil near Wanatah, IN (PPAC, 2001-2006) # Tillage Corn/Soybean Continuous Corn Yield Gain for Rotation Bu/ac % of c/d/fc yield Bu/ac % of c/d/fc yield % Chisel/disk/field cultivator 201.5 187.7 7 Chisel/field cultivator 198.0 98 186.7 99 6 Disk/field cultivator 204.3 101 186.5 99 10 Strip-till 203.2 101 186.6 99 9 No-till 197.1 98 175.6 94 12 # Data from T.D. West and T.J. Vyn Tillage research in Southern Wisconsin has observed that the yields of no-till corn tend to get progressively lower with each additional year that corn follows corn (Figure 2). Thus although no-till corn yielded as well as conventionally tilled corn when first-year corn followed a single year of soybean (CS rotation) or after 5 years of continuous soybean (1C), second-year no-till corn (2C) yields were 8 bushels/acre lower and third-year corn (3C) yields were 14 bushels/acre lower than conventional tillage. The latter factor plus the 4 bushel yield advantage in the conventional tillage system for second-year corn versus third-year corn means that second-year corn yields averaged 7 bushels/acre higher than third-year corn. No-till corn seems to be best adapted for corn following rotation crops other than corn. Figure 2. Corn responses to tillage and rotation systems in Wisconsin (1987-2006). Data courtesy of Joe Lauer, University of Wisconsin. Corn Yield Response Following Five Years of Soybean