Moldboard Plow Tillage Research Articles

Influence of time of tillage on soil physical attributes in potato rotations in Prince Edward Island

In Atlantic Canada, lack of soil cover over the cool season due to conventional primary tillage in the fall, in potato rotations, leaves the soil vulnerable to redistribution processes. The suitability of shifting primary mouldboard plough tillage operations from the fall to the spring in the potato ( Solanum tuberosum L.) phase of a 3-year rotation (spring barley ( Hordeum vulgare L.)–red clover ( Trifolium pratense L.)–potato, or replacing fall mouldboard with fall chisel ploughing, was assessed over a 3-year period on Charlottetown fine sandy loam, an Orthic Podzol. A suite of soil physical attributes was used to assess the influence of primary tillage on the degree of soil loosening, permeability, and macro-structure. Potato yield and quality were also determined. Although, mouldboard ploughing provided an additional 2–10 cm of loose (i.e. penetration resistance <1.5 MPa) soil at the lower depth of the tillage zone, compared to chisel ploughing, there were no differences in soil permeability as measured by bromide movement. Soil macro-structure, or clod size, in the potato ridge just prior to harvest reflected the degree of secondary tillage rather than the influence of primary tillage. Clod size distribution in the potato ridge was not a problem for harvesting operations as clods did not exceed 20 mm in diameter. Soil permeability at the base of the potato ridge, as assessed by oxygen diffusion rate (>55 μg m −2 s −1), air permeability, and macropore continuity (quotient of air permeability and macropore volume, >100 μm 2), and soil shear strength (<22 kPa) were not limiting for root growth. However soil pore space, as reflected by bulk density (>1.25 Mg m −3) and macropore volume (<12%) would pose a soil aeration limitation in this soil-type at the base of the ridge under wet soil conditions. Potato total yield and marketable yield were not influenced by differences in primary tillage over the 3-year period. Use of spring primary tillage and replacement of the mouldboard with a chisel plough, within the potato phase of a 3-year rotation, caused little change in soil physical quality compared to the conventional tillage system and appears to be a suitable conservation tillage technique for sandy loam soils in the climate of Atlantic Canada.

Groundwater quality and crop-yield responses to tillage management on a Sparta sand

Groundwater beneath sandy soils in the Lower Wisconsin River Valley has more detections and larger concentrations of atrazine and nitrate–nitrogen (NO 3–N) than groundwater beneath other areas of sandy soils with similar genesis in Wisconsin, USA. A 2.8-ha field study initiated in 1989 compared water quality and production potential of no-tillage (NT) and moldboard-plow tillage (MB) for corn ( Zea mays L.) production with, and without, irrigation. Ridge-tillage (RT) under irrigation for corn and soybean [ Glycine max (L.) Merr.] was added in 1991 to test the value of banding herbicide and placing N in the hydrologically inactive ridge. Soybean grown under NT and MB was added in 1993. Atrazine residues and NO 3–N were determined in soil and groundwater from 1989 to 1995. Soil samples were taken to a 1.5-m depth and groundwater samples collected from the surface of the aquifer. Atrazine and NO 3–N leaching were related to rainfall and/or irrigation. Leaching of atrazine and NO 3–N to groundwater below no-irrigation treatment was similar to that under RT with enough irrigation to meet evapotranspiration demands – atrazine application in RT was only one-third of that used for NT and MB. Atrazine concentrations in soil samples were inconclusive because of limited atrazine detection. Corn yields for RT, MB and NT under irrigation to meet evapotranspiration averaged 8.6, 8.4, and 7.0 Mg ha −1, respectively. However, there were no statistical differences between RT and MB, primarily because of a different yield rank between years. Soybean yields, averaged over the study period, for MB were 3.07 Mg ha −1, which is significantly greater than that for NT at 2.07 and RT at 2.19 Mg ha −1. Atrazine loading from 1991 to 1994 under RT, where it was band applied, was 1.41×10 −3 kg ha −1year −1 compared to 3.17×10 −3 kg ha −1year −1 for broadcast applications in the MB/NT systems. Nitrate loading on a 4-year average for RT was 23.0 kg ha −1year −1 compared to 45.2 kg ha −1year −1 for MB/NT. The RT system, where atrazine was band applied over the top of the row and N was side-dressed, reduced atrazine leaching by 55% and NO 3–N leaching by 49% when compared with NT/MB where atrazine was broadcast and N not side-dressed. Selective placement of agrichemicals in hydrologically neutral zones of the RT system reduced leaching to less than one-half of that when placement was not selective.

Economics of Different Crop Rotations in New York

The 1996 Federal Agriculture and Improvement Act decouples support payments from acreage so grain producers must now devise rotations based on market prices. Economic analysis of rotation studies can identify profitable rotations. The objective of this study was to determine short-term economic consequences of three rotations: (i) continuous corn (Zea mays L.), (ii) soybean [Glycine max (L.) Merr.]-corn, and (iii) soybean-wheat/red clover (Triticum aestivum L./Trifolium praetense L.)-corn. Field-scale trials were conducted from 1993 to 1996 on four farms in New York, and participating farmers performed field operations. Rotated corn yielded greater (140 bulacre) than continuous corn (127 bulacre), whereas soybean and wheat yielded 47 and 55 bulacre, respectively. The soybean-corn rotation had greater net returns ($101/acre) than the continuous corn rotation ($78/acre), despite net returns of $54/acre for soybeans, because rotated corn had greater net returns (%149/acre) than continuous corn. Wheat had negative net returns (-$40/acre) so the soybean-wheat/clover-corn rotation had the lowest net return ($54/acre). Harvesting and marketing of wheat straw would increase net returns of the soybean-wheat/clover-corn rotation to $84/acre. Sensitivity analysis for an 800-acre farm indicated that a soybean-corn rotation had the greatest whole-farm return at 1987 to 1996 New York prices ($55 721). Continuous corn had the lowest whole-farm return ($16 848). With the decoupling of support payments from acreage, New York grain farmers should adopt the soybean-corn rotation to maximize profit. New York grain farmers who market the wheat straw should consider the inclusion of wheat/clover on some of the soybean-corn acreage because close to maximum profit can be achieved while reducing potential pest problems.

Systems for Returning Conservation Reserve Program Land to Wheat (Triticum aestivum) Production

Experiments were conducted near Duke and Forgan, OK, on land enrolled in the Conservation Reserve program (CRP) that had been seeded to Old World bluestem (OWB) to evaluate tillage systems for returning CRP grassland to winter wheat production. Glyphosate controlled OWB 72% or less in no-till (NT) wheat. Disk tillage (DT) and moldboard plow tillage (MPT) for wheat seedbed preparation controlled OWB 87 and 99%, respectively, at Forgan and 96 and 100%, respectively, at Duke. At Forgan, OWB control in NT was higher when glyphosate was applied in July than when applied in May. Soil water content to a depth of 120 cm at planting was as high in DT and MPT without herbicide as in NT with 1,680 g ae/ha glyphosate. Within NT and MPT, glyphosate did not consistently increase soil water content compared to the respective nontreated checks. In DT, soil water content to a depth of 120 cm was greater following glyphosate at 1,680 g/ ha than without glyphosate. Wheat density was greater in DT and MPT than in NT. Compared to the NT no herbicide treatment, tillage tripled wheat yields. Wheat yields were often greater where glyphosate was applied before tillage. No-till wheat production immediately after CPR in Oklahoma without prior destruction of accumulated OWB residue does not appear feasible.

Alternative weed management strategies in conservation tillage systems for white beans (Phaseolus vulgaris L.)

White bean producers often perceive that increased herbicide inputs are required with the adoption of conservation tillage. Acceptance of conservation tillage systems for this crop would increase if effective weed management practices were assured. In 1991 and 1992, various weed management strategies were evaluated in white bean (Phaseolus vulgaris L.) grown with three tillage systems at two sites in southern Ontario. Experiments were newly established each year following corn harvested for grain. Primary tillage treatments were fall moldboard plowing, fall chisel plowing, and first-year no-till. Combinations of mechanical weeding, metobromuron [3–(4–bromophenyl)–1–methoxy–1–methylurea] herbicide broadcasted at two rates, and a band application of the herbicide were investigated in each tillage system. Timely rotary hoeing reduced weed numbers in moldboard plow and chisel plow treatments, but was not effective in no-till. Weeds were adequately controlled in all tillage systems with mechanical treatments following a herbicide either broadcasted at a reduced rate or banded over the crop row. Metobromuron broadcasted at the full recommended rate alone controlled weeds in no-till; in contrast, the degree of weed control was poor without mechanical cultivation in both moldboard and chisel plow systems. Integrating mechanical and chemical control methods was more beneficial in tilled systems. Overall weed populations were lower in first-year no-till than moldboard plow or chisel plow tillage systems. White bean producers who adopt conservation tillage under conditions similar to those investigated can be assured of effective weed management alternatives as well as bean yields equivalent to conventional tillage. Key words: Conservation tillage, weed management, rotary hoe, inter-row cultivation, Phaseolus vulgaris

Weed species diversity in spring barley varies with crop rotation and tillage, but not with nutrient source

The development of sustainable farming systems depends on our ability to predict and manage the response of weed communities to changes in cropping practices. A study was established at Normandin, Québec, Canada, to investigate the influence of liquid dairy manure and mineral fertilizer, as well as chisel and moldboard plow tillage systems, in a spring barley monoculture and a 3-yr spring barley-forage rotation that included red clover and timothy. Weed species richness (Margalef's DMG), evenness (Shannon's E), and diversity (Shannon's H') were examined in these treatments from 1992 to 1995. Nutrient source had no effect on any of the three diversity indices. Evenness values were extremely low in all years, suggesting dominance of a few weed species in most treatments. Weed species richness and diversity generally were greater in the barley-forage rotation compared with the monoculture. Tillage effects on richness and diversity varied with crop rotation. Margalef's DMGand Shannon's H' were greater in 1993 and 1995, but they were lower in 1994 when chisel was compared with moldboard plowing in the monoculture. In 1994, chickweed density was about five times greater in the chisel-plowed monoculture compared with other treatment combinations of rotation and tillage. In 1995, only one species with a density of six plants m−2occurred in the moldboard-plowed monoculture compared with three to six species and densities of 51 to 832 plants m−2in the other rotation by tillage treatments. Climatic conditions and herbicide use patterns in the different crop rotation treatments may have contributed to the more dynamic nature of weed species diversity in the barley monoculture. Reduced frequency of tillage and herbicide application; management of the forage stands, especially with regard to their termination; and improved soil resource availability likely explained the increased but more stable diversity of the weed communities in the barley-forage rotation.

Economics of Conservation Tillage Systems for CRP Land in Southern Illinois

A tillage project was initiated in 1989 at the University of Illinois Dixon Springs Agricultural Research Center in southern Illinois to evaluate conservation tillage systems for land being removed from Conservation Reserve Program (CRP). No-till (NT), chisel plow (CP), and moldboard plow (MP) tillage systems on a Grantsburg silt loam (fine-silty, mixed, mesic Typic Fragiudalf) soil were studied. Tbe soil has a fragipan at approximately 26 in. below the surface on a 6.5% east facing slope. The tillage treatments were replicated eight times on 30 by 40 ft plots. Tbe area had been in tall fescue [Festuca arundinacea (L.) Schreb.] sod. For the project, corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] were grown on a 6-yr rotation. Economic data were estimated for the three tillage systems using a simulation model to select equipment and estimate costs. The objective was to determine crop yields and to compare returns of the tillage treatments applied to CRP sod. Based on 6 yr of crop yield measurements (3 yr corn and 3 yr soybean), NT and CP systems appear to result in improved long-term productivity of sloping soil compared with MP. Machinery requirements and costs were lower with NT than with the two other tillage systems. MP had the greatest machinery requirements and highest costs and highest corn yield only in 1989. Crop yields with the NT system improved compared with the yields with MP and CP systems each year with NT resulting in the highest crop yield in the fourth, fifth, and sixth years with the differences statistically significant the last two crop years. The NT system provided the highest net income and the MP system the lowest over the 6 yr study. Net income with NT system was $32/acre per yr higher than with the CP system (simple average without time valuation adjustment) and $40/acre per yr higher than with the MP system. The NT system reduced soil loss from erosion to below the current and future soil loss standards.

Spatial Relations between Oat Residue and Ceramic Spheres when Incorporated Sequentially by Tillage

AbstractSpatial characterization of crop residues and agrichemicals incorporated by tillage is needed to interpret biomass‐related soil processes. This study presents such a characterization. We first described oat residue (Avena sativa L.) and green‐sphere distributions produced by chisel plow (CP) and moldboard plow (MP) tillage and then described red‐sphere distributions when incorporated during secondary tillage. Finally the co‐location of incorporated oat residue and colored spheres was characterized. Green and red ceramic spheres were surrogates for shoot residue and incorporated agrichemical, respectively. Characterizations were derived from weights of soil and residue and counts of spheres in soil cores (1.84 cm diam. by 30 cm long, sectioned into 15 sublengths each 2 cm long). Penetration with MP was 25 cm, CP was 15 cm, and cultivator was 17 cm. The MP incorporated 67% of residue in the 10‐ to 20‐cm depth, while more that 90% of the incorporated residue in the CP was between 1 and 11 cm deep. Secondary tillage had negligible influence on these depth distributions. Green‐sphere distributions were related more closely to tool penetration than those of oat residue because root and shoot tissue were not distinguished. Fractional porosity of the 5.32‐cm3 volumes, adjusted to account for oat residue and sphere volumes, was increased ≈12% due to these materials. Many 5.32‐cm3 volumes contained no oat residue, whereas only a few volumes had concentrations ≥4 times the mean residue concentration. Although oat residue was incorporated with primary tillage, residue and herbicide surrogates were co‐located in 35% of the volumes, many of which contained large concentrations of residue. Exclusive use of either primary tillage with the same secondary tillage produces an environment for characteristically different bioactivity in the upper 10 cm.

Influence of Controlled Drainage‐Subirrigation on Surface and Tile Drainage Nitrate Loss

AbstractControlled drainage‐subirrigation (CDS), conservation tillage, and corn (Zea mays L.) production practices were evaluated as methods of reducing NO−3 loss through tile drainage. Controlled drainage‐subirrigation was used to manage water from precipitation and subirrigation. Samples of tile drainage (5801) and surface runoff (3274) water were collected with autosamplers during each runoff event over a 3‐yr period. Annual tile drainage volumes were reduced 24% with CDS compared with the drainage (DR) treatments. Flow weighted mean NO−3 concentration of tile drainage water was reduced 25% from 10.6 mg N L−1 for the DR treatments to 7.9 mg N L−1 for the CDS treatments. The average annual NO−3 loss was reduced 43% from 25.8 kg N ha−1 for the DR treatment to 14.6 kg N ha−1 for the CDS treatments. Eighty‐eight to 95% of the NO−3 losses from all treatments occurred in the noncrop period (1 Nov.–31 Apr.). Conservation tillage in combination with CDS reduced annual NO−3 losses 49% (11.6 kg N ha−1) when compared with the conventional moldboard plow tillage and DR treatment. Annual NO−3 loss through surface runoff was increased to 1.9 kg N ha−1 with the CDS treatments compared with 1.4 kg N ha−1 with the DR treatment, this loss was minor compared with losses incurred through tile drainage. Controlled drainage‐subirrigation is a technological advancement in soil and water management as it enables farmers to minimize the effect of dry summers on crop growth and reduce NO−3 contamination of drainage water.

Microclimate effects of crop residues on biological processes

Residues from crops left on the soil surface have an impact on the microclimate, primarily temperature, within the soil and the atmosphere; but, the impact on the biological system is largely unknown. Residue is assumed to have a positive impact on the biological system in the soil and a negative impact on crop growth. This report investigates the effect of standing residue on the microclimate surrounding a cotton (Gossypium hirsutum L.) crop in a semi-arid environment and the effect of flat residue on the seasonal soil temperature and soil water regimes in a humid climate with a corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] production system. A study was conducted during 1987 and 1988 in a semi-arid climate at Lubbock, Texas using standing wheat stubble to shelter cotton from wind. In this study soil water, microclimatic variables, and plant growth were measured within standing stubble and bare soil during the early vegetative growth period. Air temperatures were warmer at night within the standing residue and the air more humid throughout the day. This led to a reduction in the soil water evaporation rate and an increase in the water use efficiency of the cotton plant within the stubble. Studies on corn residue with continuous corn and corn-soybean rotations with no-till, chiselplow, and moldboard plow tillage practices in central Iowa showed that the average soil temperatures in the upper soil profile were not affected by the presence of flat residue after tillage. Diurnal temperature ranges were most affected by the residue throughout the year. The largest effect of the residue on soil temperature was in the fall after harvest when no-till fields cooled more slowly than tilled fields. In the spring, surface residue decreased the soil water evaporation rate and increased the soil water storage within the soil profile covered with residue. In years with below normal rainfall, the additional stored soil water due to the surface residue was used by the plant to maintain transpiration rates at optimal levels during the early vegetative growth period. The biological implications of crop residue on the soil surface can be more positive than negative and increasing our understanding of the physical environment and biological system interactions will lead to improved resource management.

Test of the LEACHP Model for Predicting Atrazine Movement in Three Minnesota Soils

AbstractLeaching Estimation and Chemistry Model‐pesticide (LEACHP) was evaluated for predicting atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine) movement in sandy loam (sandy, Typic Hapludoll), silt loam (fine‐silty, Typic Hapludoll), and clay loam (fine‐loamy, Typic Haplaquoll) soils under moldboard and chisel plow tillage practices. Atrazine distribution in the root zone was measured by analyzing soil cores. Model predictions were compared with observed atrazine concentrations in the soil profiles on various dates after application (two to three growing seasons). Model performance was evaluated by testing whether model predictions fall within a specified factor of true values and using Goodness‐of‐Fit tests (maximum error, root mean squared error, coefficient of determination, modelling efficiency, coefficient of residual mass). LEACHP predicted depth of peak atrazine concentration in the soil profile accurately in all three soils (under both moldboard [MB] and chisel plow [CP] treatments and at all sampling dates). It predicted depth of atrazine movement and atrazine concentrations in the soil profile reasonably well in the Estherville soil (sandy, mixed, mesic Typic Hapludoll) except some disparities between measured and predicted concentrations in 1988 because of the difficulty in recovering representative samples. In Port Byron (fine‐silty, mixed, mesic Typic Hapludoll) and Webster soils (fine‐loamy, mixed, mesic Typic Haplaquoll), depth of atrazine movement and atrazine concentrations in the soil profile were predicted reasonably well during relatively dryer years (1988 and 1989). In a relatively wet year (1987), however, the model did not predict significant amounts of atrazine at depths &gt;45 cm, whereas, 2.5 to 27.5 µg kg−1 of atrazine were detected in soil samples during earlier sampling dates (43, 73 DAA in Port Byron and 14, 43 DAA in Webster soils). Overall performance of the model was similar in both tillage treatments (MP or CP). Considering the broad range in soil properties and climatic conditions used in testing, the model performed well.

Maize Grain Yield Response to Tillage and Fertilizer Nitrogen Rates on a Tara Silt Loam

AbstractEffects of tillage on the appropriate fertilizer N applications needed to achieve maximal grain yield are poorly denned. The study objective was determination of relative corn grain yield response to N application rate for four tillage practices: no‐tillage (NT), ridge tillage (RT), fall chisel plowing (CP) and fall moldboard plowing (MP). Maize (Zea mays L.) grain yield and N accumulation were monitored over a 6 year period with the same tillage treatment and the same fertilizer N rate applied each year to each plot. Two hybrids, differing in relative maturity rating, were planted each year. Fertilizer N rates ranged from 10 to 190 kg ha−1 and consisted of 10 kg ha−1 of liquid starter N applied at planting with varying amounts of fall applied anhydrous ammonia. With only starter fertilizer, grain yields increased with tillage intensity in the order NT ≤ RT ≤ CP ≤ MP. With ≥ 55 kg total applied Nha−1, 6 year average grain yields were unaffected by tillage. Total N removed in grain annually with only starter fertilizer ranged from 25–85 kg ha−1 Maximal amounts of N removed, about 145 kg N ha−1, occurred with 100–145 kg applied N ha−1 for all tillage treatments under the more favorable climatic conditions. Several interactions affecting grain yield appear climatically sensitive with exception of tillage by fertilizer N interactions. Because of variability in climate, planting dates varied by almost 4 weeks. Relative yield loss due to planting delay were Fertilizer N (mean change ≅−124 –−275 kg ha−1 day−1) &gt; Starter N only and MP (mean ≅− 259 kg ha−1 day−1) &gt; other tillages in general. Yield loss due to delayed planting ranged from 0.0–275 kg ha−1 day−1. Grain yield gains due to early spring soil temperatures were 16.0–21.8 kg ha−1 index‐degree−1 with MP tillage and averaged 2.7– 16.7 kg ha−1 index‐degree−1 more than those of other tillage‐hybrid combinations.

Atrazine and Metolachlor Loss in Surface and Subsurface Runoff from Three Tillage Treatments in Corn

AbstractConservation tillage with residue management has been proposed as the most effective means to reduce soil deterioration in southwestern Ontario. Two conservation tillage treatments, ridge (RT) and zero (ZT) tillage, were compared with conventional moldboard plow (CT) tillage from 1987 to 1990 for atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methyethyl)‐1,3,5‐triazine‐2,4‐diamine], deethylatrazine [6‐chloro‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine], and metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl)acetamide] loss in surface runoff and tile discharge. Twenty‐five to 44% of the annual rainfall resulted in total field runoff (surface runoff or tile discharge). Conservation tillage increased surface runoff 42% and decreased tile discharge 15% compared with conventional tillage, but total field runoff was the same from all treatments. Runoff events shortly after herbicide application produced the greatest herbicide concentrations and losses in both surface runoff and subsurface drainage. Averaged over years, herbicide concentration in surface runoff and tile discharge was, respectively, 1.3 and 1.8 times greater from conservation than conventional tillage. Conservation tillage altered the source of herbicide loss compared with conventional tillage, but environmental factors after herbicide application were more important in determining total herbicide loss than tillage. Deethylatrazine was found in both surface runoff and tile drainage and accounted for 10 to 27% of combined atrazine and drethylatrazine loss.

Characterisation of water transmission properties in tilled and untilled soils using tension infiltrometers

Tension infiltrometer (TI) measurements from a silty clay loam soil (Winchester, Ont.), a sandy soil (Hancock, WI), and a silt loam soil (Rosemount, MN) were used to: (i) characterise near-saturated hydraulic conductivity ( K 0) and flow-weighted mean radius of soil macropores ( R 0); (ii) distinguish differences in these water transmission properties between no-till (NT) and mouldboard plough (MP) continuous maize ( Zea mays L.) production systems. The K 0 values increased by about two orders of magnitude as the pressure heads ( P 0) set on the TI membranes were increased incrementally from the minimum values ( P 0=−10 cm or −15 cm) to the maximum value ( P 0=0 cm). This indicates that substantial networks of water-conducting soil macropores exist in continuous maize production systems, regardless of soil texture or tillage treatment. For each P 0 value, the MP treatment had a consistently higher K 0 than NT at the Winchester and Hancock fields sites, and a consistently lower K 0 than NT at the Rosemount field site. Regardless of soil type, most R 0 pores occurred in the 0.1–0.3 mm size range for both NT and MP soils, but NT had two to three times more of these R 0 pore sizes, as well as smaller and larger R 0 pores, than MP. This probably reflects a more consolidated soil matrix (enrichment of smaller R 0 pores) and a greater number of large cracks and biopores (larger R 0 pores) in NT soils, owing to the absence of annual loosening of the soil matrix and disruption of macropores that occurs with MP tillage. Relationships between K 0 and R 0 were complex but consistent within and between tillage treatments. A physical interpretation for this behaviour is given which employs capillary theory for water entry, and interactions among the size, number and morphology of water-conducting macropores during the infiltration process. It was concluded that the TI technique is effective for characterising differences in K 0 and R 0 between NT and MP continuous maize production systems.

Long-term tillage effects on soil quality

Public interest in soil quality is increasing, but assessment is difficult because soil quality evaluations are often purpose- and site-specific. Our objective was to use a systems engineering methodology to evaluate soil quality with data collected following a long-term tillage study on continuous corn ( Zea mays L.). Aggregate characteristics, penetration resistance, bulk density, volumetric water content, earthworm populations, respiration, microbial biomass, ergosterol concentrations, and several soil-test parameters (pH, P, K, Ca, Mg, Total-N, Total-C, NH 4-N, and NO 3-N) were measured on Orthic Luvisol soil samples collected from Rozetta and Palsgrove silt loam (fine-silty, mixed, mesic Typic Hapludalfs) soils. Plots managed using no-till practices for 12 years before samples were collected for this study had surface soil aggregates that were more stable in water and had higher total carbon, microbial activity, ergosterol concentrations, and earthworm populations than either the chisel or plow treatments. Selected parameters were combined in the proposed soil quality index and gave ratings of 0.48, 0.49, or 0.68 for plow, chisel, or no-till treatments, respectively. This indicated that long-term no-till management had improved soil quality. The prediction was supported by using a sprinkler infiltration study to measure the amount of soil loss from plots that had been managed using no-till or mold-board plow tillage. We conclude that no-till practices on these soils can improve soil quality and that the systems engineering methodology may be useful for developing a more comprehensive soil quality index that includes factors such as pesticide and leaching potentials.

Effects of tillage, nitrogen placement, and wheel compaction on denitrification rates in the corn cycle of a corn‐oats rotation

Abstract Denitrification rates under various tillage systems were determined in the corn (Zea mays L.) cycle of a corn‐oats (Avena sativa L.) rotation. Denitrification was measured directly with an in‐situ soil cover method which supplied the soil with acetylene (C2H2) and evacuated the nitrous oxide (N2O) produced. Denitrification rates were measured in both a field or non‐wheel track (NWT) area and in a compacted wheel track (WT) area for the no‐till (NT), chisel plow (CH), moldboard plow (MP) tillage systems after nitrogen (N) was applied by broadcast/incorporation with 112 kg N/ha as ammonium nitrate. Nitrogen was also applied to the NT treatment by injection with modified anhydrous ammonia knives prior to planting. Most of the cumulative N loss occurred over a 22 day period following heavy rainfall in June. Denitrification was greatest on days after rainfall events for the NT systems. Cumulative N loss was estimated at 25, 16, and 11 kg N/ha from May 29‐September 8 for NT, CH, and MP treatments, resp...

Long‐Term No‐tillage Effects on Soil Properties and Continuous Corn Yields

AbstractLack of soil disturbance in no‐tillage changes some of the most important basic soil properties. Short‐term changes have been well documented by previous research, but little is known about long‐term changes. This study was to determine the effects of 20 yr of continuous corn (Zea mays L.) under no‐tillage (NT) and conventional moldboard plow tillage (CT) with 0, 84, 168, and 336 kg N ha−1 on soil properties and grain yields and, to the extent possible, compare 20‐yr results with previously published 5‐ and 10‐yr results. Soil organic C and N; extractable P; exchangeable Ca, Mg, and K; and pH were significantly higher with NT than CT in the 0‐ to 5‐cm depth. Below the 5‐cm depth, Mehlich III P; pH; and exchangeable Ca, Mg, and K were higher with CT than NT. Organic C and N increased with increasing N rates. Conversely, pH and exchangeable Ca and Mg declined with high N rates. Bulk density was not significantly different among NT, CT, and bluegrass sod (Poa pratensis L.), but increased with depth. Comparisons of 1989 results with those obtained in 1975 and 1980 revealed that the soil's organic C was restored to the level of the bluegrass sod following a decline of 19% with CT and 9% with NT between 1970 and 1975. Grain yields, which declined along with organic C, have not recovered. Changes in organic matter content, with their many ramifications, are probably the most important long‐term effects of tillage differences on basic soil properties.

Mycorrhizal Development and Phosphorus Absorption in Maize under Conventional and Reduced Tillage

AbstractArbuscular mycorrhizae participate in P uptake by maize (Zea mays L.). Previous studies using pot‐grown plants have shown that P uptake by maize is greater when soil is not disturbed between cropping and planting. This study was conducted to determine if mycorrhizal colonization and shoot P absorption in the field are higher under reduced tillage, under conditions of soil fertility and tillage management representative of commercial farming. Maize was sampled in 1990 and 1991 from plots maintained under no‐till (NT), and ridge tillage (RT). These were contrasted with maize from plots given moldboard plow (MP) tillage each year, which disturbs the soil to a greater extent. Plots were fertilized at recommended rates. In the early part of both years, shoot P concentration in NT and RT were significantly greater than under MP. These differences in shoot P did not persist after the six‐leaf stage. Greater development of mycorrhizae in the early season was seen in the RT and NT systems relative to that in MP. There were no significant effects of tillage on final yield, possibly due to the relatively high soil P levels. Under NT and RT, arbuscular colonization had a maximum at 48 d after planting (DAP) of 55% and 60%, respectively, followed by a linear decrease to near 10% at 166 DAP. Under MP, a plateau of 45% arbuscular colonization was sustained between 48 and 97 DAP, followed by a linear decrease similar to that in NT and RT.

Agroecosystem management effects on soil carbon and nitrogen

The cumulative effects of long-term (1980–1990) tillage and crop rotation management on soil organic C and N concentrations and potential mineralization were determined. Tillage systems studied were conventional moldboard plow tillage and conservation tillage, with various crop rotations including: continuous soybean ( Glycine max L.)-wheat ( Triticum aestivum L.) cover (SW); continuous corn ( Zea mays L.)-wheat cover (CW); and corn-wheat cover-soybean-wheat cover (CWSW). Surface soil (0–5, 5–10, and 10–20 cm depth increments) organic C and N concentrations and potential mineralization were determined for all tillage/rotation combinations in October 1990. After 10 years, surface soil organic C and N concentrations were 67% and 66% higher, respectively, under conservation tillage than plow tillage to a depth of 10 cm. Potential C and N mineralization followed a pattern similar to organic C and N distribution. However, differences in substrate quality below 10 cm indicated that conservation tillage promoted N immobilization. Crop rotation had less effect than tillage on soil organic C and N amounts and potential mineralization. Rotations with higher frequency of corn (CW and CWSW) had higher organic C and N concentrations and C mineralization than SW; crop rotation had no effect on potential N mineralization. Tillage system apparently influenced soil organic matter concentrations and mineralization via crop residue incorporation rather than any effects owing to concentration differences at the soil surface, while the effect of crop rotation was related to amount of crop residues added between 1980 and 1990.

Evaluation of strip tillage systems for corn production in Ontario

Strip tillage, which involves cultivation of a narrow strip in the row area, has the potential advantages of providing a suitable seedbed for corn ( Zea mays L.) production with minimum energy expenditures, while leaving surface residues in the interrow area to reduce soil erosion. A study was conducted where three rotary tillage implements (Howard Rotaspike, Howard Rotavator, and Lely Roterra, The Lely Corporation, Suffolk, UK) and a former interrow cultivator were modified to cultivate a strip 25 cm wide in the row area. These strip tillage implements were compared with fall moldboard plow, fall chisel plow, and no-till tillage systems for 3 years of continuous corn production on sandy loam, silt loam, and clay loam soils in southern Ontario. The strip tillage treatments left significantly higher amounts of surface residue than either the moldboard plow or the chisel plow and thus provided potential soil conservation benefits. The moldboard plow system resulted in a greater proportion of fine aggregates in the seedbed than strip tillage, and strip tillage generally had more fine aggregates than no-till. Plant growth with strip tillage tended to be delayed compared with the moldboard plow treatment on all three soils. Average strip tillage yields were 10.3 and 12% lower than the moldboard plow treatments for the silt loam and clay loam soils, respectively. On the clay loam soil, differences were not significant between the strip tillage and chisel plow or no-till treatments. On the sandy loam soil, average strip tillage yields were significantly lower than the moldboard plow treatment in 1 year out of 3, equal to chisel plow in all 3 years, and higher than no-till in 2 years out of 3. Among the strip tillage treatments, the Howard Rotaspike and Howard Rotavator often resulted in finer seedbeds, better plant growth, and higher yields than the Lely Roterra and strip-till cultivator. The Howard strip tillage implements tended to compare most favorably with the moldboard plow tillage system.