Mesic Typic Argiudoll Research Articles

Simulated Small‐Channel Bed Scour and Head Cut Erosion Rates Compared

AbstractConcentrated‐flow erosion is often a major part of cropland erosion. The concentrated‐flow processes of bed scour and head cut need improved characterization to better predict and prevent erosion. This study was conducted to compare the erosion rates due to simulated small‐scale bed‐scour (Db) and head‐cut (Dh) processes. A 6.4‐m‐long by 0.15‐m‐wide hydraulic flume was used to simulate concentrated‐flow erosion on five Midwestern soils: Barnes (fine‐loamy, mixed Udic Haploboroll), Forman (fine‐loamy, mixed Udic Argiboroll), Mexico (fine, montmorillonitic, mesic Udollic Ochraqualf), Sharpsburg (fine, montmorillonitic, mesic Typic Argiudoll), and Sverdrup (sandy, mixed Udic Haploboroll). For slopes of 1.5, 3.5, and 5.0%, flow rates of 3.78, 5.67, 7.65, 11.34, and 15.12 L min−1 were used to provide a range from low (0.5 Pa) to moderate (2.5 Pa) shear stresses (τ). Soil detachment rates are functions of slope, flow rate, and shear stress. Slope, flow, their squares, and the slope × flow interaction were highly significant predictors of Db. Only flow, its square, and its interaction with slope were significant predictors of Db. Nonlinear power regressions using τ as an independent variable were better predictors of detachment than simple linear regressions. Erodibility for the soils from this study does not relate well with soil erodibility calculated using the Universal Soil Loss Equation. Differences in the slope and intercept of detachment vs. τ exist among soils. The value of Db was at least four times greater than Db for all soils at equal slope and flow rate, indicating that head cutting is the main process of detachment for the conditions tested.

Long Term Tillage Effects on Grain Yield and Soil Properties in a Soybean/Grain Sorghum Rotation

In Nebraska, early adopters of conservation tillage, especially those using no-till planting, had some concerns regarding planter performance, early season weed control, and possible yield reductions. Selected tillage and planting systems were used long term to evaluate effects on soybean [Glycine max (L.) Merr.] and grain sorghum [Sorghum bicolor (L.) Moench] yield, soil properties, and residue cover in a nonirrigated rotation. The six tillage and planting systems selected for evaluation were: no-tilI, no-till with row-crop cultivation, disk, double disk, chisel, and plow. In 1981, two sets of field plots were established near Lincoln, NE, on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudolls) so that both crops could be evaluated each year

Tillage, Rotation Sequence, and Cultivar Influences on Brown Stem Rot and Soybean Yield

Yield of soybean [Clycine max (L.) Merr.] is often reduced when grown in fields using no-till (NT) and shorter crop rotations with corn (Zea mays L.) than with conventional tillage (CT) and longer crop rotations. The objective of this study was to determine the effect of tillage system, rotation sequence, and cultivar on severity of brown stem rot (BSR) [caused by Phialophora gregata (Allington and D.W. Chamberlain) W. Gams] and yield of soybean. Field studies were conducted near Arlington, WI, for 4 yr (1989-1992) on a Plano silt loam (fine-silty, mixed, mesic Typic Argiudoll) under both NT and CT [...]

Soybean seed yield and nutrient diagnoses as related to plant nutrient balance

Abstract Both nutrient concentrations and nutrient ratios of plants have been associated with crop seed yields, but research examining their relative correlation to yield is scarce. Furthermore, research comparing nutrient diagnoses by the modified‐diagnosis and recommendation integrated system (M‐DRIS) against diagnoses resulting from use of M‐DRIS concentration means as critical nutrient levels (CNL's) is lacking. Consequently, a soybean [Glycine max (L.) Merrill] cultivar by phosphorus (P) by potassium (K) by limestone soil fertility field study conducted on a Cresco loam (fine‐loamy mixed, mesic Typic Argiudoll) was used to determine: (i) whether plant nutrient concentrations or ratios better accounted for differences in soybean seed yield; and (ii) whether diagnostic systems that use nutrient concentrations or nutrient balance are more accurate in diagnosing soybean P and K status. Correlation analyses demonstrated that both nutrient concentrations and nutrient ratios were related to yield, but parti...

Grain Sorghum Yield Response to Nonuniform Stand Reductions

AbstractNonuniform stand reductions caused by poor emergence, insect damage, or other factors, occur frequently in grain sorghum [Sorghum bicolor (L.) Moench] fields. This research was conducted to determine the effect of within‐row skip patterns on grain yield and yield component compensation, particularly for hybrids differing in tillering ability. Dryland field studies were conducted at Manhattan (Reading silt loam, fine‐silty, mixed, mesic Typic Argiudoll) and St. John (Naron fine sandy loam, fine‐loamy, mixed, thermic Udic Argiustoll), KS, during 1988 and 1989. Two medium‐maturity hybrids, DeKalb DK‐46 and Pioneer 8500, were selected based on low and high tillering ability. Plots were three rows, with the middle row containing a within‐row skip pattern. Results were analyzed separately by skip row, adjacent row, and average for the three rows. Skip lengths within a 7.6‐m row were 0.9 m, 0.9 m repeated three times, and 2.7 m within the skip row, and the 0.9 m × 3 pattern in all three rows. Yield of the skip row was reduced by every configuration bordered by control stand adjacent rows. Yield compensation from adjacent rows and within the skip row compensated for reduced stands, except for a 2.7−m skip resulting in 5.1% yield reduction, 64% uniformly spaced stand in all three rows with 6.9% yield reduction, and three 0.9 m within‐row skips in all three rows with 10.9% yield reduction. Compensation was primarily in number of heads per plant and seeds per head. Difference in hybrid tillering response did not influence grain yield. Thus, yield reduction is likely only where skips result in severe plant spacing nonuniformity.

Soybean Growth and Yield after Simulated Bean Leaf Beetle Injury to Seedlings

AbstractAlthough the bean leaf beetle [Cerotoma trifurcata (Forster)] is a major pest of seedling soybean [Glycine max (L.) Merr.], the effects of beetle injury on soybean growth and yield are poorly understood. This study was conducted to characterize growth and yield responses of soybean to simulated bean leaf beetle injury occurring during seedling stages. Also, single‐day and sequential defoliation techniques were compared. The study was conducted on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudoll) in a soybean (‘Elgin 87’) field near Mead, NE. Treatments consisted of an undefoliated check and various levels (0‐80%) of simulated bean leaf beetle defoliation (sequential and single‐day) and/or cotyledon removal. Cotyledons were removed at stage VC, sequential defoliation was begun during stage V1, and single‐day defoliation was imposed on the last day of the defoliation period (late V3). Soybean yield significantly decreased 12% as seedling defoliation increased to 68%. Seedlings experiencing sequential defoliation did not reach a critical LAI of 3.5 until well into their reproductive stages, limiting light interception and dry matter accumulation. Cotyledon removal coupled with defoliation also reduced height up to 28% at R2.1 and delayed canopy development up to 11 d. Cotyledon removal reduced leaf area development of the seedling soybean 32%. Plants without cotyledons required up to 34% less defoliation than plants with cotyledons to delay canopy development and reduce yield. Single‐day defoliation techniques were less accurate than sequential defoliation techniques and overestimated the amount of leaf tissue a continuously defoliating insect would remove.

Simulating Natural Drainage under Turfgrass in Chemical Fate Studies

Simulation of field conditions is important when conducting solute movement research in the greenhouse. A study was initiated to develop and test a solute movement system with intact turf‐soil columns subjected to suction approximating field capacity and typical irrigations. Intact soil columns from a Sharpsburg soil (fine montmorillonitic, mesic Typic Argiudoll) planted to Kentucky bluegrass (Poa pratensis L.) were encased in concrete, excavated, and brought to the greenhouse. Porous ceramic plates were attached to some column bottoms and suction (50 kPa) was applied to simulate soil water matric potentials at field water capacity and eliminate perched water tables. Under 2.5‐cm irrigations, evapotranspiration (ET) was 15% greater (P = 0.09) from columns without suction than from columns with suction. Drainage was 460% greater (P = 0.08) from columns under suction receiving 2.5‐cm irrigation. Volume of drainage water and total bromide collected was significantly greater (P = 0.01 and 0.02) from columns under suction receiving 5.0‐cm irrigations than from columns receiving 2.5‐cm irrigations. Averaged bromide concentrations in the drainage did not differ among treatments. Water and solute movement may be underestimated in greenhouse studies using containers without suction plates to eliminate perched water tables.

Monoculture and Rotation System Effects on Precipitation Use Efficiency of Corn

AbstractDevelopment and utilization of cropping systems in rainfed areas are highly dependent on their water use efficiencies, especially in subhumid areas. The objective was to evaluate the effect of crop rotation and N fertilizer rates on precipitation use efficiency by dryland corn (Zea mays L.). Corn was grown under rainfed conditions at Mead, NE, on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudoll) in four cropping systems: (i) continuous corn, (ii) a 2‐yr soybean [Glycine max (L.) Merr.]‐corn rotation, (iii) a 4‐yr rotation of oat [Avena sativa (L.)] + clover [80% Melilotus officinalis Lam. and 20% Trifolium pratense L.]‐grain sorghum [Sorghum bicolor (L.) Moench]‐soybean‐corn, and (iv) a 4‐yr rotation of soybean‐grain sorghum‐oat + clover‐corn. Nitrogen fertilizer rates used for corn were 0, 90, and 180 kg N ha−1 as NH4NO3. Corn grain precipitation use efficiency was significantly affected by year, rotation, and N fertilizer rates from 1984 through 1991. Precipitation use efficiency ranged from 36 to 137 kg ha−1 cm−1 for continuous corn and from 57 to 165 kg ha−1 cm−1 for corn grown in rotation from 1984 through 1991. Precipitation use efficiency was greater in rotation (101.8 kg ha−1 cm−1) than in continuous corn (83.6 kg ha−1 cm−1). In dryland production areas, cropping systems with greater and more stable precipitation use efficiency can reduce crop failures.

Soil Fumigation within Monoculture and Rotations: Response of Corn and Mycorrhizae

AbstractThe causative factors for corn (Zea mays L.) response to methyl bromide (CH3Br) fumigation, in the absence of known specific pathogens, are unknown. This study was conducted to determine if deleterious nonspecific rhizosphere microorganisms are the causative agents. Soil fumigation was postulated to increase yield of continuous corn but to have less effect on the yield of corn grown in rotation, because more deleterious rhizosphere microorganisms were suspected in monoculture than in rotation. The effects of fumigation and crop rotation on corn grain yield, plant height and P content, available soil N and P, mycorrhizal infection, and soil microbial biomass were investigated at two sites near Mead, NE, on a Sharpsburg silty clay loam soil (fine, montmorillonitic, mesic Typic Argiudoll). Methyl bromide treatments were applied prior to planting for 4 yr at one site and 2 yr at the other site. The sites differed in fertilization, pest management, and crop sequences, but both contained continuous corn. Fumigation resulted in an increase in grain yield under monoculture only once in six site years. Unexpectedly, however, fumigation resulted in a decrease in grain yield under rotation in 7 of 12 observations. Plants in fumigated soil were P‐deficient early in the growing season despite similar soil test P concentrations in control and fumigated plots. Fumigation reduced mycorrhizal infection and soil microbial biomass. Mycorrhizal infection of corn shortly after germination appears to be important to initial corn growth in this soil. Fumigating soil revealed a considerable biological influence on corn growth and yield by reducing both deleterious and beneficial microorganisms.

Fractal Description of Soil Fragmentation for Various Tillage Methods and Crop Sequences

AbstractSoil structure has been difficult to quantify and, at best, has been studied semiquantitatively. Fractal representation of soil fragmentation can provide an indication of soil structure. The purpose of our study was to use fractal analysis to quantify soil fragmentation under various tillage and crop sequence treatments at different times during the growing season. We collected soil samples from four tillage treatments (established 10 yr earlier) of chisel, disk, no‐till, and moldboard plow in factorial arrangement with two crop sequences of corn (Zea may L.)‐soybean [Glycine max (L.) Merr.]‐corn (C‐S‐C), and soybean‐corn‐soybean, (S‐C‐S) on a Sharpsburg (fine, montmorillonitic, mesic Typic Argiudoll) soil. Aggregate‐size distribution was used to calculate fractal dimension (D) for each treatment. Higher D values indicate greater soil fragmentation and a soil dominated by smaller aggregates. The opposite is true for lower D values. Differences in soil fragmentation observed for tillage treatments after autumn tillage became even greater over winter. Soil fragmentation increased over autumn and winter, with D increasing in the order of plow > chisel > disk > no‐till. Formation of larger soil aggregates increased during the growing season for all tillage systems. The D values for C‐S‐C were smaller than S‐C‐S in the no‐till, indicating that the previous year's corn in C‐S‐C provided more large aggregates. Soybean appears to have negative effects on large‐aggregate formation in no‐till. Aggregate densities, averaged across tillage and crop sequence, increased from 1.25 to 1.77 Mg m−3 as the aggregate diameter decreased from 6.38 to 0.162 mm. Fractal analysis was found to be useful in determining soil fragmentation differences due to different tillage methods and crop sequences.

Controlled Wheel Traffic Effects on Soil Properties in Ridge Tillage

AbstractRidge‐till is gaining widespread use on highly erodible land. Matched‐width equipment has allowed producers to establish permanent traffic lanes in ridge‐till. The establishment of permanent traffic lanes and a lack of preplant tillage has increased concern about soil compaction. The purpose of our study was to assess the effects of long‐term controlled tractor wheel traffic on soil properties of a ridge tillage system. This research was conducted on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudoll) in southeastern Nebraska. A split‐split‐plot design was employed to evaluate differences in soil properties among corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] crops; row, trafficked interrow, and nontrafficked interrow positions; and depths of 0 to 7.5, 7.5 to 15, and 15 to 30 cm. Axle load of the tractor used on the plots was 4 mg. Sampling was conducted in the summer after ridging. Most variability in soil properties among positions was confined to the 0‐ to 7.5‐cm depth. Bulk density, soil strength, aggregate mean weight diameter (MWD), water content at field capacity (FC), and water content at wilting point (WP) tended to be highest in the trafficked interrow and least in the row. Saturated water content and gravitational water (GW) were generally highest in the row and least in the trafficked interrow. Soil strength in the trafficked interrow was 56% greater than the nontrafficked interrow and 104% greater than the row. Similar, but less pronounced differences among positions were also observed for bulk density. Aggregate mean weight diameter in the trafficked interrow indicated that wheel traffic resulted in larger aggregates while ridging resulted in smaller aggregates in the 0‐ to 7.5‐cm depth of the row. Mean saturated hydraulic conductivity (Ksat) in the trafficked interrow was approximately one‐quarter of the mean value for the nontrafficked interrow and row. Organic C and TN were greater in the row than the interrow positions. The influence of tractor wheel traffic on soil properties was largely dissipated by the 15‐ to 30‐cm depth. Because of the dissimilarity in soil properties among positions, ridge‐tilled fields should be conceptualized and managed as three distinct soil zones, not as a single unit.

Influence of Pollination Pattern on Intrapanicle Caryopsis Weight in Sorghum

Recent studies have shown that changes in grain‐fill rates within the sorghum [Sorghum bicolor (L.) Moench] panicle cause caryopsis weights to decrease from the apex to the base. Pollination pattern in the sorghum panicle is also basipetal. The objectives of this study were to determine if pollination pattern influences intrapanicle caryopsis weights and to determine which components of grain fill are affected by pollination pattern. Field studies were done in 1990 at Manhattan, KS, on a Reading silt loam [fine‐silty, mixed, mesic Typic Argiudoll (0–1% slope)] and Hays, KS, on a Barney silt loam [fine, montmorillonitic, mesic Typic Argiustoll (0–1% slope)]. At Manhattan, eight pollination‐pattern treatments were applied to DeKalb DK 46 and its male‐sterile parent, 97A. At Hays, a male‐sterile hybrid, KS56A × KS47B, received four of the eight treatments. Panicles were divided into four equal sections; apex, upper middle, lower middle, and base. Different pollination patterns were applied to the sterilized panicles by exposing the appropriate sections to pollen. Differences in caryopsis weights and weight components were determined using analysis of variance and linear regression analyses. In all cases, intrapanicle caryopsis weights followed the pollination pattern applied. The panicle sections pollinated first had caryopses that were from 1.0 to 2.5 mg heavier than those found in the sections pollinated later. Pollination pattern influenced caryopsis weight by influencing grain‐fill rates within the panicle; the length of the grain‐fill period did not change. Apparently, caryopses that were pollinated first were better competitors for assimilates than those pollinated later.

Yield Responses of Alfalfa to Simulated Alfalfa Weevil Injury and Development of Economic Injury Levels

AbstractAlthough the alfalfa weevil Hypera postica (Gyllenhal)] is an important alfalfa (Medicago sativa L.) pest, relatively little is known about how defoliation at specific plant developmental stages affects yield. This study was conducted to characterize yield responses of alfalfa to simulated alfalfa weevil injury when injury was initiated at the early bud stage of the first growth cycle and to develop economic injury levels for the alfalfa weevil. The study was conducted on a silty clay loam (fine, montmorillonitic, mesic Typic Argiudoll) in a 3.6‐ha alfalfa (cv. Haymaker) field near Walton, NE. Sixteen 1 by 1‐m plots were arranged in a randomized complete block design with four treatments in each of four replicates. Treatments consisted of three levels of simulated alfalfa weevil defoliation and an undefoliated check. Leaflets were removed over 10 d. Dry matter yield and stem density responses were measured for both the first and second growth cycles. Simulated alfalfa weevil injury did not affect stem density before the first cutting or during the entire second growth cycle. When injury occurred during the early bud stage, the most significant effect was the loss of leaf tissue. Yield differences among treatments for the first growth were highly significant, and the relationship between percentage defoliation and percentage yield reduction was linear both years. Defoliation injury imposed during the early bud stage of the first growth cycle did not affect yields or stem densities of the second growth cycle. Dry matter yield responses of the first growth cycle were used to calculate economic injury levels for third and fourth instars feeding at the early bud stage of alfalfa development.

Caryopsis Weight Patterns within the Sorghum Panicle

Understanding the intrapanicle pattern of caryopsis weights commonly found in sorghum [Sorghum bicolor (L.) Moench] fields and the factors that result in changes in this pattern would help in determining limitations on caryopsis weight. Our objectives were to determine the pattern of caryopsis weights found in the sorghum panicle, the effect of assimilate supply on the weight pattern, and whether this pattern resulted from the rate of grain fill or length of the effective fill period (EPP). Two dryland field studies were conducted at Manhattan, KS, in 1989 and 1990 on a Reading silt loam (fine‐silty, mixed, mesic Typic Argiudoll; 0–1% slope). In 1989, panicles of DeKalb ‘DK 46’ and Pioneer ‘8500’ tagged at anthesis were harvested at regular intervals. In 1990, seven population‐light treatments were applied to Pioneer 8500 either at anthesis or 7 d after anthesis. Panicles from both experiments were separated into four sections. Caryopses from these sections were used to determine differences in caryopsis weights, rate of grain fill, and length of the EPP. In 1989, caryopsis weights within the sorghum panicle increased from 20.2 mg caryopsis−1 at the base to 22.8 mg caryopsis−1 at the apex. In 1990, this same intrapanicle pattern was observed in all treatments that had medium or high plant populations during the EPP. This pattern was caused by increases in the rate of grain fill from the base to apex of the panicle. In the low population treatments in 1990, caryopses in the middle of the panicle were as heavy or heavier than those in the apex. This was the result of intrapanicle grain‐fill rates that were more uniform and an increase in the length of the EPP from the apex to the base of the panicle.

Mobility of aniline, benzoic acid, and toluene in four soils and correlation with soil properties

Soil properties and retention mechanisms affecting the relative mobility of aniline, benzoic acid, and toluene in Cecil sandy loam (clayey, kaolinitic, thermic Typic Hapludults), Holdredge silt loam (fine-silty, mixed, mesic Typic Argiustolls), Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudolls), and Valentine fine sand (mixed, mesic Typic Ustipsamments) were delineated in laboratory studies. The effect of the synthetic organic compounds (SOCs) was also determined on effective organic campounds (SOCs) was also determined on effective cation exchange capacity (ECEC) of the soils. Benzoic acid was most mobile of the SOCs but was retained in the Cecil soil by hydrogen bonds to Fe oxides. Toluene was least mobile and probably was hydrophobically sorbed to all soils. Aniline was electrostatically retained in protonated form to organic and inorganic exchange sites of the soils and reduced the ECEC of aniline-treated Holdredge and Sharpsburg soils.

Tillage and Crop Rotation Affect Corn, Soybean,and Winter Wheat Yields

There is little research in northern regions on tillage systems in corn (Zea mays L.), soybean [Glycine max (L.) Merr], and wheat (Triticum aestivum L.) rotations. The objectives of this study were to (i) evaluate the influence of tillage on performance of corn, soybean, and winter wheat in rotations with each other, and (ii) determine whether corn or soybean yields could be increased in 3-yr rotations with wheat compared with an annual rotation with each other. Field studies were conducted near Arlington, WI, for 3 yr (1989 to 1991) on a Plano silt loam soil (fine-silty, mixed, mesic Typic Argiudoll) under both moldboard plow (MP) and no-till (NT). Six crop sequences evaluated were: corn/soybean, corn/soybean/wheat, corn/wheat/soybean, and continuous corn, soybean, or wheat [...]

Defoliation during vegetative growth of corn: the shoot: root ratio and yield implications

The objective of this field study was to measure the effect of defoliation during vegetative growth of corn ( Zea mays L.) on the shoot: root ratio. The yield from the various treatments would be used to validate a version of the crop-growth and yield model CERES-Maize that responds to defoliation. This field study was conducted near Mead, Nebraska in 1989 on a Sharpsburg silt loam (fine montmorillonitic, mesic Typic Argiudoll). The experiment was a randomized complete-block design with four blocks consisting of the factorial combination of 50 and 100% defoliation at the 7th and 12th visible leaf collar stages. A non-defoliation treatment was included for comparisons. The root, stem, sheath, leaf blade and ear dry weights were measured six times during the growing season. Corn plants defoliated during vegetative growth were able to reallocate dry matter such that within 7 days the shoot: root ration of the defoliated plants was similar to the control. Yields from the 100% defoliation treatments closely agreed with the predictions from a modified version of CERES-Maize.

Evaluation of Alternative Screening Criteria for Selecting Nitrogen‐Use Efficient Genotypes in Sorghum

Development of N‐use efficient genotypes could reduce crop N fertilizer requirements; however, determining N uptake and utilization efficiencies can be costly and time consuming. The purpose of this study was to evaluate alternate screening criteria for determining relative N‐use efficiencies in sorghum [Sorghum bicolor (L.) Moench]. Different sorghum genotypes were evaluated at two soil N levels in three separate experiments on either a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudoll) or a modified Ortello fine sandy loam soil (coarse‐loamy, mixed, mesic Udic Haplustoll). Uptake efficiency was defined as total plant N per unit soil N (PN/SN), biomass utilization efficiency as total aboveground dry matter per unit PN (NE1), and grain utilization efficiency as grain dry weight per PN (NE2). For each experiment, Spearman rank correlation coefficients were calculated for relationships between N‐use efficiency traits and alternative screening criteria. Total plant dry weight (TDW), TDW/grain N (GN) and harvest index (gram dry weight/TDW) were the best predictors of genotypic performance for PN/SN, NE1 and NE2 (r = 0.89, 0.68, 0.82), respectively. The best use of the above alternative screening criteria would be as prescreening tools to eliminate the poorest genotypes. This would alleviate the need to do wholeplant analysis on a large number of samples, yet permit a fair level of confidence in making final selections.

Residual Effects of Long-Term Nitrogen Fertilization on Nitrogen Availability to Corn

Long-term use of N fertilizer in continuous corn (Zea mays L.) is a common practice in the Corn Belt of the USA, but little information is available on the residual effects of this pratice. The objectives of this study were to determine the effects of long-term N fertilizer use on subsequent N response and the implications of these effects on N availability and management recommendations. Three long-term N fertilizer treatments (LTN1, LTN2, and LTN3) were applied to a continuous corn study from 1958 to 1983 on a Plano silt loam (fine-silty, mixed, mesic Typic Argiudoll) in Wisconsin (...)

Placement and Timing of Nitrogen Fertilizers for Conventional and Conservation TillageCorn Production

Increased use of reduced tillage to meet soil and water conservation goals in corn (Zea mays L.) production emphasizes the need to manage fertilizer N efficiently in these systems. A 3-yr study to evaluate N fertilizer source, placement, and timing options in four tillage systems was conducted on a Plano silt loam (fine-silty, mixed, mesic Typic Argiudoll) and a Manawa silty clay loam (fine, mixed, mesic Aquollic Hapludalf) using a split-split plot treatment arrangement with four replicates. Main plot treatments were moldboard plow (MP), chisel plow (CP), ridge-till (RT), and no-till (NT). Sub-plot treatements were rates of 90 and 180 Ib N/acre, and sub-sub-plot treatments were seven N application (NAM) (...)