No-till Corn Research Articles

Remote Sensing for Identification of Weeds in No-till Corn

Weeds infesting crop fields are rarely uniformly distributed, especially under minimum-tillage practices. Therefore, the total amount of herbicide chemicals used can be greatly reduced by first identifying the location and type of weed patches in the fields, and then applying the correct type and concentration of chemical to those areas. This research is aimed at developing a remote sensing technique for identifying and mapping weed patches.

Western Corn Rootworm Larval Control, 1993

Abstract Thirty-one insecticides were applied for control of WCR larvae in no-till and conventional tillage corn. The test plot was planted in a continuous corn field on the UK Spindletop Research Farm on 7 May in a RBD with 3 replicates of no-till and 3 replicates of conventional tillage. Individual plots consisted on single rows, 8 m long, with 96.5 cm row spacing. All plots received Accent 75WDG (0.0313 lb [AI]/acre) on 14 Jun. All insecticide treatments were applied at planting except the 2 Furadan 4F treatments, which were broadcast and banded, respectively on 25 May. Number of lodged plants per plot was recorded 28 Jul. A plant was considered lodged if the angle between the base of the plant and the ground was less than 45°. Root damage ratings were evaluated on 29 Jun by examining 3 plants per plot using the Iowa 1-6 system. Data were subject to ANOVA and treatment means compared to that of the control by Dunnett’s test.

Reduced-Herbicide Weed Management Systems for No-Tillage Corn (Zea mays) in a Hairy Vetch (Vicia villosa) Cover Crop

Weed management treatments with various degrees of herbicide inputs were applied with or without a hairy vetch cover crop to no-tillage corn in four field experiments at Beltsville, MD. A hairy vetch living mulch in the no-treatment control or a dead mulch in the mowed treatment improved weed control during the first 6 wk of the season but weed control deteriorated in these treatments thereafter. Competition from weeds and/or uncontrolled vetch in these treatments without herbicides reduced corn yield in three of four years by an average of 46% compared with a standard PRE herbicide treatment of 0.6 kg ai/ha of paraquat plus 1.1 kg ai/ha of atrazine plus 2.2 kg ai/ha of metolachlor. Reducing atrazine and metolachlor to one-fourth the rate of the standard treatment in the absence of cover crop reduced weed control in three of four years and corn yield in two of four years compared with the standard treatment. Hairy vetch had little influence on weed control or corn yield with any herbicide treatments.

Weed and Corn (Zea mays) Responses to a Hairy Vetch (Vicia villosa) Cover Crop

Field studies were conducted in 1990 and 1991 to determine the effects of corn planting date and hairy vetch control method on the efficacy of fall-planted hairy vetch as a weedsuppressive cover crop for no-till corn. Glyphosate controlled hairy vetch when applied at the early bud growth stage (April), but hairy vetch residue provided no weed control compared to the weedy check. Mowing was not an effective means of suppressing hairy vetch at the early bud stage. Untreated hairy vetch reduced weed biomass 96% in 1990 and 58% in 1991 but reduced yield over 76% in April-planted corn. There was no competition of untreated hairy vetch with corn when corn planting was delayed until May or June (mid- or late-bloom growth stages of hairy vetch). Corn planted in May into untreated hairy vetch yielded similarly to corn planted in a no-cover weed-free check.

Pesticides and Nutrients In Southern U. S. Shallow Ground Water and Surface Runoff

Nutrient and pesticide concentrations in shallow groundwater (3m) and surface runoff were determined for conventional-till (CT) and no-till (NT) soybean watersheds. Groundwater NO3N concentrations were similar for both tillage systems, averaging about 7-8 ppm, but exceeded 10 ppm for some storms. Annual mean groundwater NO3N concentrations were only 0.34 ppm in a riparian zone downslope from the CT watershed. Higher nutrient concentrations in NT surface runoff reflected surface residue leaching. Runoff from both watersheds, 2 days after a broadcast application of 0-20-20, had high nutrient concentrations that decreased during subsequent storms. Pesticide concentrations in groundwater of the NT watershed were as high as 250 ppb at a depth of 1.5 m within 1 week after application (1st rainfall). Concentrations beneath the CT watershed were < 10 ppb maximum. One month after application, pesticide concentrations in groundwater beneath both watersheds had decreased to about 10% of their respective 1-week values. Similar total pesticide losses in runoff occurred for both tillage systems. NT reduced sediment loss but increased pesticide movement into the soil profile. Results of companion studies with corn at another site indicated similar trends for nutrients and pesticides in shallow groundwater. Within 11 months after application, herbicides were still detectable at very low concentrations (<1 ppb). Soil insecticides, applied at planting, were not found in groundwater. Herbicides and insecticides were detectable in both the water and sediment phases of runoff for 5 months after application. At the 1.5-m depth, the mean NO3N concentration in groundwater for conventional-, reduced-and no-till corn was 4.78 ppm compared with 6.96 ppm at the 3-m depth.

Profitability of No-Tillage Corn following a Hairy Vetch Cover Crop

Hairy vetch (Vicia villosa Roth subsp. villosa), as a winter legume cover crop, fixes atmospheric N 2 for following crops and improves the soil. A 3-yr field study (1985-1988) was conducted in the Maryland Coastal Plain and Piedmont to assess the agronomic and economic characteristics of a hairy vetch cover crop on no-till corn (Zea mays L.) compared with corn systems preceded by winter fallow and winter wheat (Triticum aestivum L.) cover crops. No-till corn following a hairy vetch cover crop yielded more than no-till corn following winter fallow and winter wheat cover crops at comparable fertilizer N rates in the Coastal Plain and Piedmont over 3 yr. The highest yielding combinations were a hairy vetch cover crop with 120 Ib N/acre in the Coastal Plain and a hairy vetch cover crop with 40 Ib N/acre in the Piedmont [...]

Hemp Dogbane (Apocynum cannabinum) and Wild Blackberry (Rubus allegheniensis) Control in No-tillage Corn (Zea mays)

Hemp dogbane and wild blackberry have become significant weed problems in no-tillage corn production in Maryland. Nicosulfuron (31 to 62 g ha−1) plus crop oil concentrate (COC) gave 67% or more hemp dogbane and wild blackberry control. There was no difference in hemp dogbane or wild blackberry control between 31 and 94 g ai ha−1nicosulfuron. Tank mixtures of 2,4-D or dicamba with nicosulfuron gave 72 to 100% hemp dogbane and wild blackberry control. Hemp dogbane control following applications of 560 g ha−12,4-D was 97% in 1989 and 63% in 1990. Wild blackberry control with 2,4-D was 40% both years. Dicamba at 280 g ha−1gave 70 and 55% control of hemp dogbane and 75 and 65% control of wild blackberry in 1989 and 1990, respectively. Triclopyr plus 2,4-D provided 72 to 98% hemp dogbane control and 92 to 98% wild blackberry control. However, triclopyr plus 2,4-D applied at 280 plus 560 g ha−1injured corn, and corn yields were reduced compared with weedy controls in 1990.

Management and Urease Inhibitor Effects on Nitrogen Use Efficiency in No-Till Corn

No-till corn (Zea mays L.) production is common in the Mid-Atlantic region and urea-ammonium nitrate solution (UAN) and urea are by far the most common N fertilizers used in the region. Because of the potential for ammonia volatilization from these sources when they are surface-applied to no-till corn, it is necessary to know how the method and time of application affect the N fertilizer use efficiency (grain yield, N uptake, and ear-leaf N concentration per pound of N applied) obtained with them. We also wanted to determine if the urease inhibitor amendments ammonium thiosulfate (ATS) and N-(n-butyl)thiophosphoric triamide (NBPT) would increase the N fertilizer use efficiency of UAN and urea surface applied to no-till corn [...]

No-Till Systems for Corn following Hay or Pasture

No-till (NT) corn (Zea mays L.) production following perennial forages can reduce soil loss and machinery and labor requirements; yet few farmers in the northern USA are using this practice. Research has indicated NT corn performs best when planted following fall-killed perennials; yet most farmers who practice NT apply herbicides to perennials in the spring. The objective of this study was to compare two NT systems, fall-kill NT and spring-kill NT, with farmers' current tillage (CT) systems, which included either chisel or moldboard plowing. Farmer-managed comparisons were made in field-sized, replicated strip tests on silt loam soils on six farms in 1988 and 1989. Variables measured were percentage residue cover after planting, harvest plant populations, and grain moisture and yields. Residue cover averaged 13, 53, and 72% for CT, fall-kill NT, and spring-kill NT, respectively. Spring-kill NT, compared with CT and fall-kill NT, resulted in reduced plant populations at three of six farms and 3% higher average grain moisture. Fall-kill NT produced yields equal to, or higher than, CT and spring-kill NT at all farms. Averaged over all farms, production costs per bushel were lowest for fall-kill NT, intermediate for CT, and highest for spring-kill NT. Despite these advantages, use of fall-kill NT may be limited by (i) farmers' preferences for evaluating hay stands in the spring, before deciding where to plant corn; (ii) fall grazing needs; (iii) minimum requirements for crop residue cover after corn planting; and (iv) shortage of labor in the fall. Research Question Most producers who plant no-till following perennial forage species apply herbicides to kill perennials in the spring, rather than the fall. Farmers have not made side-by-side on-farm comparisons of corn planted no-till following spring-killed and fall-killed perennials to evaluate relative yields, management challenges, and economics. The objective of this study was to compare two no-till systems (fall-kill no-till and spring-kill no-till) with farmers' current tillage systems, which included either chisel or moldboard plowing. Literature Summary Growers' major concern about planting corn no-till into perennial forages is the application timing and efficacy of herbicides to control perennials. Previous research has indicated that split herbicide treatments, either in the fall or early spring and at planting, were needed to completely control perennial vegetation. No-till systems using fall Roundup (glyphosate) applications have consistently resulted in yields comparable to those with moldboard plowing. Results for corn planted no-till with spring-kill of perennials have been inconsistent, with performance highly dependent on spring rainfall. Study Description Farmer-managed comparisons were made on silt loam soils on six Wisconsin farms in 1988 and 1989. Treatments: Fall-kill no-till (Glyphosate applied to kill perennial species in the fall) Spring-kill no-till (Glyphosate or atrazine applied to kill perennial species in the spring) Current tillage (Fall or spring chisel or moldboard plowing) Additional weed control, soil fertility, insect control, hybrids, and other cultural practices varied with farms but were similar within sites for the three tillage systems. Applied Questions Which no-till system (fall- or spring-kill) resulted in best performance? No-till corn planted following spring-kill of perennial forage vegetation resulted in greatest residue cover after planting (Table 1), which probably would provide best soil erosion control. But spring-kill no-till resulted in inconsistent weed control, variable plant stands and corn growth, and reduced average yields compared with growers' current tillage systems (Table 1). With fall-kill no-till, weed control was effective and grain yields were always comparable to, or greater than, current tillage systems. Average corn production cost per bushel was lowest for fall-kill no-till, intermediate for current tillage systems, and highest for spring-kill no-till. Given these production advantages, why have few farmers adopted fall-kill no-till for corn following forage perennials? Fall-kill no-till requires growers to use a fixed crop rotation schedule, with the decision to rotate to corn made the previous fall. Growers prefer to assess forage crop winter survival in the spring as a basis for crop rotation plans. Other constraints, such as the need for fall grazing and labor shortages at corn harvest time, may prevent fall herbicide applications. In addition, crop residue cover from fall-killed vegetation, as low as 30% after planting (Table 1), may not provide adequate soil erosion control on steep slopes. Table 1. Average residue cover after planting, plant populations at harvest, grain yield, and production cost for corn grown under three tillage systems at six farms. Tillage system Residue cover Harvest population Grain yield Production cost ---- % ---- plants/acre × 1000 bu/acre ----- $/bu ---- Current tillage 13 22 114 2.42 (4–40)† (18–26) (62–163) (1.25–3.88) Fall-kill no-till 53 23 120 2.30 (30–67) (19–26) (74–162) (1.29–3.64) Spring-kill no-till 72 21 98 4.68 (57–89) (15–29) (20–176) (1.21–11.80) † Range of values across six farms.

Crimson Clover Reseeding Potential as Affected by s-Triazine Herbicides

Economic savings can result from allowing a crimson clover (Trifolium incarnatum L.) cover crop in no-tillage corn (Zea mays L.) systems to self-reseed and thereby eliminate the need for annual seeding operations. Research has indicated, however, that self-reseeding of crimson clover is variably sensitive to certain residual corn herbicides, depending on growth stage at time of herbicide application. Accordingly, a 2-yr experiment was conducted to evaluate the effects of atrazine, cyanazine, and simazine applied to crimson clover at four growth stages (late vegetative, early bloom, late bloom, and early seed set) on subsequent clover reseeding potential. All successfully reseeded crimson clover plots were sampled in 1990 and 1991 for dry matter (DM) and total N concentration []

Threshold Control of Armyworm on No-Till Field Corn, 1992

Abstract An experiment was conducted in 1992 in Pulaski County, VA, to determine the effectiveness of Asana XL and 2 formulations of Lorsban (4 E and 4 E-HF) against amryworm in field corn. Plots were established in a 7 acre field. The recent cropping history for this field included field corn planted in 1990 and 1991 followed by a cover crop of barley each year. Corn rows were spaced at 30 inches. The field was being scouted every 5 to 6 d for armyworm. On 16 Jun armyworm levels in the field approached the established economic threshold. Armyworms were early 5th instar and corn was at the 6 to 8 leaf stage. The experimental design was a randomized complete block with 4 replications. Each plot was 4 rows wide by 50 ft. Treatments were applied on 18 Jun. Just before and 7 d after treatments were applied, armyworms were counted on 25 corn plants in the middle 2 rows of each plot. A backpack sprayer, fitted with stainless steel 8002VS spray tips, was used to broadcast the insecticides approximately 18 inches above the corn canopy. The sprayer was calibrated to deliver a rate of 20 gal/acre at 40 psi. Approximately 0.1 to 0.2 inches of rain fell on the plots shortly after the Lorsban treatments were applied. Data analysis were done using SAS.

Corn Rootworm Larval Control on Field Corn, 1992

Abstract Two experiments were conducted in Rockridge Co. Virginia to determine the effectiveness of several experimental and commercial granular insecticides against corn rootworm larvae. The 1st experiment evaluated the effectiveness of Lorsban 15 G with 3 experimental formulations of Lorsban 15 G (i.e., XRM 4372, XRM 5362, and NAF), whereas the 2nd experiment evaluated the effectiveness of 1 experimental and 3 commercial granular insecticides. Both experiments were conducted near the center of a no-till corn field which had been in continuous corn production since 1988. The field had not been treated with granular insecticides at planting since 1988, and the predominant soil type of the field is an Alonzville fine sandy loam. Both experiments consisted of a randomized complete block design, with all treatments replicated 3 times in the first experiment and 4 times in the second experiment. All plots were 30-ft long and consisted of 2 rows spaced 30 inches apart. A John Deere, 2-row Max-Emerge planter was used to plant all plots on 22 May at a population density of 24,200 seeds per acre. Insecticide granules were applied in front of the press wheels either directly in the seed furrow or in a 5-inch wide T-band over the furrow, depending on the treatment. Each of the regular granular insecticide applicators was removed from the planter and replaced with a wooden device designed to hold inverted pint canning (Mason) jars used in dispensing the insecticide granules. Attached to the underside of the wooden holders was a plastic funnel and tube through which the insecticide granules flowed. A single opening, drilled into the lid of each jar, was laboratory-calibrated to deliver insecticides accurately at a speed of 3 mph. The possibility of mixing 1 or more insecticides was avoided by using a separate jar and lid for each treatment. At the start of application, 2 jars containing the appropriate insecticide granules were inverted and placed in the wooden holders. This method helped minimize soil compaction because the tractor made only 1 pass per plot. The roots of 5 consecutive corn plants were dug from the check plots of each experiment on 14 Jul and washed of excess soil. Likewise, the roots of 5 consecutive corn plants were dug from each of the remaining treatment plots on 17 Jul and washed of excess soil. Corn rootworm damage ratings were made the same day that the corn roots were dug and were based on the Iowa 1-6 scale (1–no feeding; 6–3 or more root nodes completely destroyed). Stand counts were not made because of irregular seed spacing that occurred in 1 of the rows during planting. The statistical analysis for both experiments involved ANOVA and Fisher’s LSD to test for differences among treatment means.

Black Cutworm Control in No-Till Corn, 1992

Abstract Nine insecticide formulations were evaluated for control of black cutworm larvae. The test plot was planed in a continuous com field on the UK Spindletop Research Farm in Fayette Co., KY, on 1 May as a randomized block design with replicates. Individual plots consisted of 2 rows of no-till corn, 11 m long, with 96.5 row spacing. All insecticides were applied as a T-band at planting with a Gandy granular applicator. Gramoxone Extra 2.5 S and Bicep 6 WDL were applied on May 1, 1992, for weed control at 2.25 pt/acre and 2.4 qt/acre, respectively. Ten-inch aluminum barriers were buried 4 to 5 inches into the soil around a 2 m by 2 m section in the middle of each plot. Plants began to emerge on 12 May. On 15 May, 16 third instar black cutworms, obtained from the USDA-ARS Com Insect Research Unit, Ankeny, IA, were released inside each of the barriers. Stand counts and numbers of cut plants were recorded on 15, 16, 19, 22, and 25 May. A plant was considered cut if at any time it was cut off by cutworms; regrowth was disregarded. Data were transformed by acrsin-squareroot then subjected to ANOVA and treatment means compared to the control by LSD (SAS Institute).

Nitrogen Management in Furrow Irrigated, Ridge-Tilled Corn

Use of conservation tillage methods, including ridge-tillage increases crop residue cover which can increase loss of urea-based fertilizers. Objectives of this study were to evaluate N sources, rates, methods, and times of application for ridge-tilled, furrow-irrigared corn (Zea mays L.) on a Crete silt loam soil (fine, montmorillionic, mesic Pachic, Argiustoll) near Scandia, KS. When averaged over 5-yr, grain yields were less with urea-ammonium nitrate (UAN) broadcast and dribbled treatments than with anhydrous ammonia (AA) preplant knifed, 28% UAN solution preplant knifed, and split applications of UAN knifed or dribbled. Surface dribbled UAN proved to be no more effective than surface broadcasting [...]

Weed Control in Oat (Avena sativa)-Alfalfa (Medicago sativa) and Effect on Next Year Corn (Zea mays) Yield

Field experiments were conducted from 1985 through 1989 to evaluate herbicide selectivity and impact on seeding-year yields of spring oat and underseeded alfalfa, and carryover weed control benefits from increased legume-fixed N for second-year dryland no-till corn. PRE metolachlor, pendimethalin, and prodiamine controlled green foxtail and POST bromoxynil or 2,4-DB controlled broadleaf weeds. These herbicides caused 0 to 20% alfalfa injury and 0 to 17% oat injury, and increased oat yield one of three years but did not increase the yield of underseeded alfalfa. POST pyridate, thifensulfuron, and tribenuron were too injurious to either oat, alfalfa, or both crops. Forage yields of annual ‘Nitro’ and perennial ‘Wrangler’ alfalfa seeded alone were greater than when they were underseeded in oat, with herbicides applied in both systems. As a result of drought in 1988 and 1989, yield of second-year corn planted after one-year alfalfa was not increased from potentially greater legume-fixed N. Dryland corn yield following monoculture oat or corn was 254% higher than corn following alfalfa.

Role of lumbricus terrestris (L.) burrows on quality of infiltrating water

Long-term watershed studies at the North Appalachian Experimental Watershed, Coshocton, Ohio have shown that when corn ( Zea mays L.) is planted in soil covered by the residue of the previous crop (i.e. no-tillage management), surface runoff from summer storms is greatly reduced. In addition, the residue cover provides a favorable environment for various soil invertebrates, especially earthworms. During high-intensity rainstorms, some of the water that infiltrates in no-till corn fields moves rapidly downward in burrows made by the earthworms Lumbricus terrestris L. Samplers were developed for collecting infiltrating rain water flowing in L. terrestris burrows at a depth of 45cm below the soil surface. With annual surface applications of 175 kg N ha −1 as NH 4NO 3, concentrations of NO 3-N in water flowing in individual burrows during growing season storms ranged up to 152 mg l −1. Concentrations of NO 3-N tended to be lowest after prolonged wet soil conditions and highest after intermittent warm, dry periods. Distilled water poured directly into the surface openings of L. terrestris burrows and immediately collected as it drained into samplers, contained up to 40 mg of NO 3-N I −1, a value greater than that measured in many of the samples resulting from natural rain storms. Water and herbicide mixtures poured through L. terrestris burrows showed that the linings of the burrow, or drilosphere, may contribute nitrogen to the infiltrating water while greatly reducing the concentrations of atrazine and alachlor.

Spatial and Temporal Variability of Carbofuran Degradation in Soil

AbstractLoss of pesticide efficacy resulting from enhanced rates of microbial degradation has been observed with several pesticides including the insecticide carbofuran (2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranyl methylcarbamate). Soils in which this phenomenon occurs are often referred to as “problem soils.” Several previous studies have documented the temporal aspects of the conversion of a nonproblem soil to a problem soil, and have compared carbofuran degradation rates in problem vs. nonproblem soils. There have been few studies of the spatial or temporal variability of pesticide degradation, and no studies of the variability of carbofuran degradation, however. Our study was designed to evaluate the spatial variability of carbofuran degradation activity in a conventional‐till and a no‐till corn (Zea mays L.) field, and to assess temporal variations of carbofuran degradation activity. Soil samples were collected at two positional locations in each field (in‐row and between‐row) at three times during the growing season. Within the planting furrow, maximum rates of carbofuran degradation were higher and resulting half‐lives of carbofuran (DT‐50%) were lower than in samples collected between corn rows. Interactive effects of both microbial biomass and soil water content appeared to contribute to the observed differences in carbofuran degradation kinetics as well as to the positional differences observed. Temporal variations in carbofuran degradation appeared to be dominated by soil water content. At this time it remains unknown whether the observed increase in carbofuran degradation activity, in the row, occurred in response to the banded application of carbofuran, or to increased C availability in the rhizosphere.

Response of No-Till Corn to Nitrogen Source, Rate, and Time of Application

A 3-yr N-source study was conducted on a site where urea was known to be less effective than NH4NO3 (AN) for no-till corn (Zea mays L.) production. The purpose of the study was to compare two urea-containing N sources thought to have lower N loss potential than AN and urea at two rates and times of application. Sources evaluated were urea, AN, Tennessee Valley Authority (TVA) experimental urea nitric phosphate (UNP) and TVA experimental urea ammonium phosphate (UAP). The soil was a Pope (coarse-loamy, mixed, mesic Fluventic Dystrochrept), which is an acid soil with a C.E.C. of 12.1 cmol/kg and organic matter content of 3.7%. Nitrogen rates of 80 and 160 lb/acre were broadcast either at planting or 4 to 5 wk after planting. Experimental design was a randomized block with three replications. Results showed that AN and the TVA experimental materials performed comparably and that both were better than urea in grain yield and N content of total dry matter. Urea performed as well as the other sources in total dry matter accumulation. Delayed application of N increased grain yields from all N sources when compared with application at planting.

Banded Herbicide Applications and Cultivation in a Modified No-till Corn (Zea mays) System

The acceptance of no-till crop production systems has been limited due to expected problems with weed management. Field experiments were established at two locations in Ontario in 1988 and one location in 1989. Band or broadcast applications of preemergence (PRE) combinations of high or low label rates of atrazine with or without metolachlor or inter-row cultivation, were evaluated for their effectiveness in controlling annual weeds in no-till corn. At each location, different herbicide and cultivation combinations were required to achieve adequate weed control. Corn grain yield was equivalent regardless of whether herbicides were applied as a band or broadcast treatment at all three sites. At two of the three sites, one cultivation combined with herbicides applied as a band was adequate to maintain weed control and corn grain yields. Selective application of herbicides in bands represented an approximate 60% reduction in total herbicide applied into the environment. The integration of a shallow post-plant inter-row cultivation combined with the soil conservation attributes of no-till, would enhance the sustainability of a modified no-till corn production system.

Crop and Tillage Rotations: Grain Yield, Residue Cover, and Soil Water

AbstractInformation regarding crop yield response for different tillage and rotation systems is needed to determine regional or local suitability for a given production system. Our objective was to determine the effects of continuous and alternating tillage sequences in corn (Zea mays L.) monoculture and corn‐soybean [Glycine max (L.) Merr.] rotation on residue cover, soil water, and grain yield. Continuous conventional tillage (CT), continuous no‐tillage (NT), or CT and NT alternating every other year were evaluated during a 5‐yr period on a Rion (fine‐loamy, mixed, thermic Typic Hapludult)‐Pacolet (clayey, kaolinitic, thermic Typic Kanhapludult) sandy clay loam complex at a Piedmont location and an Eunola sandy loam (fine‐loamy, siliceous, thermic Aquic Hapludult) at a Coastal Plain location. The 5‐yr average NT corn grain yield was 27% (1.15 Mg ha−1) higher than CT at the Piedmont location, but only 4% (0.32 Mg ha−1) higher at the Coastal Plain location. Continuous NT at the Piedmont location also resulted in higher corn yields 2 out of 4 yr compared with NT following CT. The increase in corn yield with NT was associated with greater soil water availability, primarily attributed to surface residue cover from corn stover fostering greater infiltration on a crust‐prone soil. Soybean yield during the 5‐yr period was 5% higher with NT at the Piedmont location and unaffected by tillage at the Coastal Plain location. In general, crop rotation had no effect on corn yield at either location. Results indicate that continuous NT should be the system of choice on this upland Piedmont soil.