Fall Plowing Research Articles

Monitoring Melolontha melolontha L. species in 2007, in the nursery from U.P. IV Bătrâna O.S. Topliţa, Harghita forest district.

Melolontha melolontha L. (called may bug), is the major species, the spread of this species, from Dobrogea and Câmpia Româna up in the mountains area, was detected in both woodlands: hardwood and softwood. Following surveys in the nursery of U.P.IV Bǎtrâna, in 2007, has made the prognosis for Melolontha melolontha ( may bug) for 2008. May bug larvae were reported only on 20.83% of total area. Attack will be weak in 2008. In U.P. I Cǎlimǎnel nursery, degree of infestation is average (medium), corresponding to a density of 0.27 active larvae, in to the third age, per square meter. Infested area remains the same every year, being 1880 ha, and the infestation level is low. Limiting excessive multiplication of may bug beetles can be achieved only by applying an integrated system of measures, preventive and repressive, carefully and continuous supervision of population dynamics of pests and their density, by making the prognosis works. Using integrated method, the focus is on destroying the insects in adult stage, during flight period, preventing infestation of crop land by depositing eggs, using in this purpose repressive measures (collection of beetles, treated food), and preventive measures (plowing land, soil cover, using repellent substances, using smoke, using light traps). Destroying beetles in the larval stage is done primarily by physical and mechanical methods ( inundation, catch with bait plants) and agrotechnical methods (fall plowing, plowing soil with scrapers).

Water‐Stable Aggregation in Relation to the Normalized Stability Index

In spite of the good quality of soils in Hungary, soil structure is deteriorated by intensive tillage. Because of general dissimilarities between field and laboratory circumstances and therefore lack of comparability, the former results are questionable. An optimized method initiated by Six, Elliott, and Paustian (2000) was adapted to investigate changes in soil structure and quality caused by different kinds of added organic matters. Our samples originated from the long‐term fertilization experiments in Keszthely, western Hungary. The experiments were set up in 1960. The texture of the investigated soil is sandy loam; the type of soil is Eutric Cambisol (soil type FAO) or Alfisol (soil type USDA). Tillage and its depth was fall plowing to 25 cm. Crop rotation was maize–maize–potato–winter wheat–winter wheat. Samples were taken from depths of 0–20 and 20–30 cm, from the fallow, which had the same treatment as the potato field. Changes in soil structure were quantified by wet sieving. Soil structural stability was characterized by comparing aggregate size distribution after the use of a lower and a higher disruptive force, which was simulated by two different pretreatments. Determinations were done in triplicates. Soil structure may be improved by adding readily decomposable organic matter. The extent of amelioration depends on the chemical buildup and decomposability of the crop residues. Three different kinds of organic matters were investigated: (1) maize stem (M), (2) wheat straw (W), and (3) maize stem and wheat straw (MW). By comparing the aggregate stabilizing effects of the differently decomposable organic matters to each other and predicting the lower decomposability but persisting effect of M, the expected MW > M > W order was proven. These are parallel with those results of Harris, Chesters, and Allen (1966) and John et al. (2005), who observed decreasing aggregate stability in the M > W order. We observed increased macroaggregate stability in both macroaggregate fractions (2000–7000 µm and 250–2000 µm) in all three case of organic‐matter addition, but these newly formed bindings were easily broken up because of the weaker bindings of the higher aggregate hierarchical orders. This is remarkable mainly in the upper layer because crop residues were mixed to the upper layer and therefore could not have affected the lower one. Furthermore, adding organic materials has decreased the mass of the 53–250 µm microaggregate fraction in all treatments and depth layers and in addition in both pretretments. This proves that adding organic matter enhances the transient and temporary binding agents between microaggretages grouped into macroaggregates but that these bindings are temporal.

Tillage Effects on Water Use and Grain Yield of Winter Wheat and Green Pea in Rotation

Under water‐limited conditions, increasing water use efficiency (WUE) is essential for successful crop production. A 7‐yr study (1977–1982, and 1985) to evaluate tillage and tillage timing effects on soil water storage, crop water use, and grain yield of winter wheat (Triticum aestivum L.) and spring green pea (Pisum sativum L.) in rotation, was conducted near Pendleton, OR. Treatments included (i) fall plow (FP)–fall moldboard plow after wheat and after pea, (ii) maximum tillage (MT)–fall roto‐till after wheat and fall sweep after pea, (iii) spring plow (SP)–spring moldboard plow after wheat and fall moldboard plow after pea, and (iv) minimum tillage (MinT)–no‐till (NT) after wheat and fall sweep after pea. During the wheat phase, water storage efficiency was 44, 40, 38, and 34%, for FP, MT, SP, and MinT, respectively. Corresponding values during the pea phase were 50, 53, 59, and 57%, for FP, MT, SP, and MinT, respectively. Wheat used all of the stored water and an additional 31, 41, 43, and 61% more water than water stored under FP, MT, SP and MinT, respectively. Pea used 71, 67, 67, and 60% of stored water under FP, MT, SP and MinT, respectively. Wheat and pea yields under MT, FP, and SP were not different. Lowest yield was obtained under MinT during both wheat and pea phases. WUE was highly correlated with yield and was lowest under MinT. Improving weed control, retaining stubble for soil erosion control, and reducing sweep operations in MinT should improve yields in this treatment.

Tillage Effects on Water Use and Grain Yield of Winter Wheat and Green Pea in Rotation

Under water-limited conditions, increasing water use efficiency (WUE) is essential for successful crop production. A 7-yr study (1977–1982, and 1985) to evaluate tillage and tillage timing effects on soil water storage, crop water use, and grain yield of winter wheat (Triticum aestivum L.) and spring green pea (Pisum sativum L.) in rotation, was conducted near Pendleton, OR. Treatments included (i) fall plow (FP)–fall moldboard plow after wheat and after pea, (ii) maximum tillage (MT)–fall roto-till after wheat and fall sweep after pea, (iii) spring plow (SP)–spring moldboard plow after wheat and fall moldboard plow after pea, and (iv) minimum tillage (MinT)–no-till (NT) after wheat and fall sweep after pea. During the wheat phase, water storage efficiency was 44, 40, 38, and 34%, for FP, MT, SP, and MinT, respectively. Corresponding values during the pea phase were 50, 53, 59, and 57%, for FP, MT, SP, and MinT, respectively. Wheat used all of the stored water and an additional 31, 41, 43, and 61% more water than water stored under FP, MT, SP and MinT, respectively. Pea used 71, 67, 67, and 60% of stored water under FP, MT, SP and MinT, respectively. Wheat and pea yields under MT, FP, and SP were not different. Lowest yield was obtained under MinT during both wheat and pea phases. WUE was highly correlated with yield and was lowest under MinT. Improving weed control, retaining stubble for soil erosion control, and reducing sweep operations in MinT should improve yields in this treatment.

No‐Till and Hand Hoeing Impacts on Carbon Dioxide Emissions from a Silt Loam in Northeast China

Tillage operations lead to a rapid release of carbon dioxide (CO2). However, most published studies have been related to the effects of soil preparation disturbance, such as mechanical‐powered fall or spring plowing, chiseling, or disking on CO2 emissions. Effects of soil disturbance, such as hand hoeing during plant growth, on CO2 flux are uncertain. We assessed 1) first‐year no‐till impacts and 2) short‐term (6 h) impacts of hand hoeing on fluxes of soil CO2 from a silt loam (typic Hapludolls) in northeast China, by determining CO2 built‐up in portable chambers (volume=65×65×25 cm3). No‐till practices decreased CO2 fluxes in the first year of adoption of the conservation practices compared with traditional plowing practices. Compared to no‐hoeing, a single hand hoeing operation can lead to a 2 kg CO2‐C ha−1 loss, about a 30% increase, within the first 3 hours of hoeing operation. Results suggest that no‐till practices may reduce CO2 emissions from this silt loam soil in northeast China, where farmland has been under intensive management for more than a century.

Field Pea Growth and Nutrient Uptake: Response to Tillage Systems and Nitrogen Fertilizer Applications

A two-year [1999, 2001] study of field pea (Pisum sativum L.) in rotation with small grain was conducted on a Fargo clay soil [fine, smetitic, frigid, Typic Epiaquert] to determine the influence of tillage system [fall PLOW, fall CHISEL PLOW, fall DISK, and NOTILL] and spring applied nitrogen fertilizer rates [0, 45, 90, and 135 kg ha−1] on dry matter production at three growth stages, and nitrogen–phosphorus–potassium [NPK] concentration and uptake. Plants were sampled at first flower [code 203] after 870 GDD and maximum dry matter production [code 208] after 1364 GDD. Seed was harvested for yield [code 303] after 1692 GDD. Dry matter production at flower stage 203 averaged 2400 kg ha−1 the first year and 1960 kg ha−1 the second year with the PLOW system producing the lowest dry matter in both years. Applications of nitrogen fertilizer at the high rate increased dry matter from 500 to 700 kg ha−1. Dry matter at stage 208 in 2001 ranged from 4260 kg ha−1 without fertilizer nitrogen applied, to 6360 kg ha−1 with 135 kg ha−1 of nitrogen fertilizer applied. In contrast to the earlier stage, the PLOW system produced the greatest total dry matter production at stage 208. Minimum pea seed yield, stage 303, averaged 2740 and 2410 kg ha−1 without any nitrogen fertilizer applied in 1999 and 2001. Maximum seed yields at harvest [3530 kg ha−1 in 1999 and 3140 kg ha−1 in 2001] were obtained only when 135 kg ha−1 nitrogen fertilizer was applied. Average seed yields were not always significantly different between tillage systems, but the CHISEL PLOW and DISK were consistently higher than PLOW or NOTILL at all nitrogen fertilizer rates. This research provided estimates of the amount of NPK nutrients required to maximize field pea production under various tillage systems and nitrogen fertilizer rates at various growth stages. When averaged across years, nitrogen fertilizer rates, and tillage systems, concentrations of N, P, and K were measured at 3.0, 0.30, and 2.6% at stage 203, with 2.4, 0.23, and 1.5% at stage 208 and finally the seed [stage 303] at 3.4, 0.38 and 1.2%. The pea plant required 0.031 kg N, 0.0032 kg P, and 0.027 kg K for each kilogram of plant dry matter produced by flowering stage 203. By stage 208 when the pea plant has reached maximum dry matter production, the nutrient requirement was 0.023 kg N, 0.0025 kg P, and 0.0162 kg K to produce 1 kg of plant material. By harvest, stage 303, the nutrients removed by the seed were 0.034 kg N, 0.0041 kg P, and 0.0115 kg K for each kilogram of seed produced. This study indicated that adequate nitrogen (derived from the soil, through N fixation or applied as fertilizer) was equally if not more important than tillage system and this management practice must be included in the overall plan for maxim field pea production in the Northern Great Plains.

Productivity and profitability of straw-tillage and nitrogen treatments on irrigation in southern Alberta

Straw-tillage treatment and N fertilizer rate were assessed for their impact on plant growth, N uptake, and profitability of irrigated cereals and oilseeds on a Dark Brown Chernozemic Lethbridge loam in southern Alberta. Straw was either retained or removed by baling. Tillage treatments were fall plowing, spring plowing, and direct seeding. Four N fertilizer rates (0, 50, 100, and 200 kg ha-1) were imposed on the straw-tillage treatments. The data were analyzed by crop using analysis of covariance with year and replication as random factors, straw-tillage treatment as a fixed effect, and fertilizer and fertilizer squared as covariates. Grain and straw yields were higher for fall plowing than for spring plowing or direct seeding at zero N rate, but were not different at the high N rate (200 kg ha-1). Grain and straw N concentrations were higher for fall plowing than spring plowing or direct seeding at the low N rate (50 kg ha-1), but similar at the high N rate. Total N uptake was higher for fall plowing or spring plowing without retaining straw than direct seeding without retaining straw or spring plowing with retaining straw at the low N rate, but similar at the high N rate. Net returns were higher for fall plowing and treatments that sold the straw, and were maximized at a N rate of about 100 kg ha-1. Key words: Crop residue, fertilizer nitrogen, economics, tillage timing, irrigation

Effects of tillage and inorganic fertilizers on culturable soil actinomycete communities and inhibion of fungi by specific actinomycetes

This study examined the influence of reduced tillage and varying nitrogen regimes on culturable soil actinomycete communities in soils under barley and canola in northern Alberta. Residues of barley and canola were also sampled from experimental sites in central Alberta. The 10 most commonly cultured actinomycetes (all Streptomycetes) were tested in vitro for antagonism towards 10 plant pathogenic fungi. The actinomycetes Streptomyces halstedii and Streptomyces rochei were the most antagonistic, and two unidentified others displayed some antagonistic activity. Counts of S. halstedii and total culturable actinomycetes were made in spring and fall. Fall plowing reduced both total actinomycete and S. halstedii counts in both spring and fall, and zero tillage and minimum tillage reduced S. halstedii counts in the spring only. Nitrogen had no effect on total counts, and only the lowest rate of nitrogen (0 kg ha −1) slightly reduced S. halstedii counts in the spring. S. halstedii was present on canola residues. This research indicates that differing practices within agricultural fields may not be the main determinant of actinomycete community size and diversity.

Impacts of Zone Tillage and Red Clover on Corn Performance and Soil Physical Quality

Despite extensive research, reduced corn (Zea mays L.) performance is still encountered using conservation tillage on fine-textured soils in cool humid temperate climates. These problems are intensified when corn is planted into residue from a previous crop such as winter wheat (Triticum aestivum L.). The objective of this 4-yr study was to determine the influence of fall zone tillage (ZT), no tillage (NT), and conventional moldboard plow tillage (CT) (fall plowing) on corn performance and soil physical quality under a winter wheat-corn-soybean (Glycine max L. Merr.) rotation with and without red clover (Trifolium pratense L.) (RC) underseeded in the wheat phase of the rotation. A randomized complete block design (3 x 2 factorial, 4 replicates) was established on three adjacent fields in the fall of 1996 on a Brookston day loam soil (fine loamy, mixed, mesic, Typic Argiaquoll) at Woodslee, ON Canada, and measurements were collected during 1997 to 2000. Over both wet and dry growing seasons from 1998-2000, zone tillage following underseeded RC produced average corn grain yields (7.23 Mg ha -1 ) that were within 1% of those obtained using conventional tillage (7.33 Mg ha -1 ), and 36% higher than those obtained using no tillage and RC (5.33 Mg ha -1 ). Zone tillage also improved soil quality as evidenced by generally lower soil strength than no tillage, and near-surface soil physical quality parameters that were equivalent to, or more favorable than, those of the other treatments. It was concluded that corn production using zone tillage and RC underseeding is a viable option in Brookston clay loam soil, as it retains much of the soil quality benefit of conventional tillage but still achieves most of the yield benefit of conventional moldboard plow tillage.

Impacts of Zone Tillage and Red Clover on Corn Performance and Soil Physical Quality

Despite extensive research, reduced corn (Zea mays L.) performance is still encountered using conservation tillage on fine-textured soils in cool humid temperate climates. These problems are intensified when corn is planted into residue from a previous crop such as winter wheat (Triticum aestivum L.). The objective of this 4-yr study was to determine the influence of fall zone tillage (ZT), no tillage (NT), and conventional moldboard plow tillage (CT) (fall plowing) on corn performance and soil physical quality under a winter wheat–corn–soybean (Glycine max L. Merr.) rotation with and without red clover (Trifolium pratense L.) (RC) underseeded in the wheat phase of the rotation. A randomized complete block design (3 × 2 factorial, 4 replicates) was established on three adjacent fields in the fall of 1996 on a Brookston clay loam soil (fine loamy, mixed, mesic, Typic Argiaquoll) at Woodslee, ON Canada, and measurements were collected during 1997 to 2000. Over both wet and dry growing seasons from 1998-2000, zone tillage following underseeded RC produced average corn grain yields (7.23 Mg ha−1) that were within 1% of those obtained using conventional tillage (7.33 Mg ha−1), and 36% higher than those obtained using no tillage and RC (5.33 Mg ha−1). Zone tillage also improved soil quality as evidenced by generally lower soil strength than no tillage, and near-surface soil physical quality parameters that were equivalent to, or more favorable than, those of the other treatments. It was concluded that corn production using zone tillage and RC underseeding is a viable option in Brookston clay loam soil, as it retains much of the soil quality benefit of conventional tillage but still achieves most of the yield benefit of conventional moldboard plow tillage.

Formation of the Runoff of Small Rivers in the Southern Ural Region

The formation of the runoff of small rivers in different natural zones of the cis-Urals Region is analyzed. Correlation between variations in the flood flow of small rivers and changes in the system of agricultural land use in 1936–1995 in the Southern cis-Urals is shown. The dependence of the balance of melt water on the topography and type of farming lands on the slope is discussed. The effect of fall plowing on the coefficient of snowmelt runoff is assessed.

Earthworm, infiltration, and tillage relationships in a dryland pea–wheat rotation

Dryland farming in the Mediterranean climate of the Pacific Northwest, USA supports extremely low earthworm populations under conventional tillage. Increases in earthworm populations are being observed in fields under no-till cropping systems. A 30+ year experiment with four tillage levels in a pea ( Pisum sativum L.)-winter wheat ( Triticum aestivum L.) rotation was evaluated for earthworm populations and ponded infiltration rates. Where tillage has been limited to 2.5 cm depth, Apporectodea trapezoides (Duges) mean population was 25 m −2. Plots subject to tillage by plow (25 cm depth) or chisel (35 cm depth) averaged less than 4 earthworms m −2. The shallow tillage treatment also had the highest average infiltration rate of 70 mm h −1 compared to 36 for chisel, 27 for spring plow, and 19 mm h −1 for fall plow treatments. The highly variable nature of earthworm counts and infiltration measurements prevented conclusive correlation between the two, but increases in both can be attributed to minimum tillage.

Nitrous oxide emissions from an irrigated soil as affected by fertilizer and straw management

Nitrous oxide (N2O) emission from farmland is a concern for both environmental quality and agricultural productivity. Field experiments were conducted in 1996–1997 to assess soil N2O emissions as affected by timing of N fertilizer application and straw/tillage practices for crop production under irrigation in southern Alberta. The crops were soft wheat (Triticum aestivumL.) in 1996 and canola (Brassica napusL.) in 1997. Nitrous oxide flux from soil was measured using a vented chamber technique and calculated from the increase in concentration with time. Nitrous oxide fluxes for all treatments varied greatly during the year, with the greatest fluxes occurring in association with freeze-thaw events during March and April. Emissions were greater when N fertilizer (100 kg N ha−1) was applied in the fall compared to spring application. Straw removal at harvest in the fall increased N2O emissions when N fertilizer was applied in the fall, but decreased emissions when no fertilizer was applied. Fall plowing also increased N2O emissions compared to spring plowing or direct seeding. The study showed that N2O emissions may be minimized by applying N fertilizer in spring, retaining straw, and incorporating it in spring. The estimates of regional N2O emissions based on a fixed proportion of applied N may be tenuous since N2O emission varied widely depending on straw and fertilizer management practices.

Cellulolytic population dynamics in a vertic soil under three tillage systems in the Humid Pampa of Argentina

Tillage systems impact soil biota involved in the decomposition of stubble and the biota, in turn, is responsible for the transformation of nutrients that are essential to fertility. Modifications in soil microbial populations could be indicative of alterations in the soil health caused by different management practices. The purpose of this work was to quantify the aerobic cellulolytic population as a sensitive indicator of the changes caused by stubble placement in three tillage systems: chisel (ChT), no-till (NT) and fall plow followed by NT (FP–NT), and at two depths (0–5 cm and 5–10 cm). The study was conducted on a Chernozemic clay loam soil (Vertic Argiudoll) during 1994–1996, in a corn ( Zea mays L.)-double crop wheat ( Triticum aestivum L.)–soybean ( Glycine max (L.) Merr.)-soybean rotation sequence. Samples were taken after wheat harvest. Dilution series of soil suspensions were inoculated in selective medium for cellulolytics and counts were done by most probable number (MPN). Crop residue was separated from soil by sieving and dry weight determined. No-till showed the largest number of aerobic cellulolytics in 1995 and 1996 compared to the other tillages ( p≤0.05). In respect to soil depth, NT showed a greater concentration of cellulolytics in the 0–5 cm depth. We did not find differences between tillages in the total amount of residue, but there were differences in its distribution, with residue concentrations in the NT soil, being 2.5 times higher at the 0–5 cm than at 5–10 cm soil layer. The dynamics of cellulolytic population indicated sensitivity to stubble placement. It may be possible to use it together with other properties as an indicator of changes due to management practices.

Effect of straw management, tillage timing and timing of fertilizer nitrogen application on the crop utilization of fertilizer and soil nitrogen in an irrigated cereal rotation

In irrigated grain-growing soils on Canada's prairies, straw management can affect nitrogen (N) fertility and long-term soil organic matter reserves. We conducted a 2-year field experiment in southern Alberta, on a Dark Brown Chernozemic Lethbridge loam (Typic Boroll), to determine the effects of straw removal, tillage, and fertilizer timing on crop uptake of soil and fertilizer N. During the study (1991 and 1992), the crop was oat ( Avena sativa L.) and wheat ( Triticum aestivum L.), respectively, in an experiment that had been in a wheat-wheat-oat-wheat rotation since 1986. Five straw-tillage treatments were: straw-fall plow, straw-pring plow, no straw-fall plow, no straw-spring plow and no straw-direct seeding. Fertilizer N was applied in fall or spring. Ammonium nitrate (5 at.% 15N) was added at 100 kg N ha −1 in fall 1990 or spring 1991. For oat (1991), plant N derived from soil was higher under fall plow than under spring plow, higher with tillage than direct seeding, and unaffected by straw removal. The plant N derived from fertilizer was not affected by straw removal in fall plow treatments, but under spring plow, it was higher with straw removal. The plant N derived from fertilizer showed a significant straw-tillage × fertilizer timing interaction; with fall incorporated straw, plant N derived from fertilizer was 44.0 kg N ha −1 for spring-applied, and 30.6 kg N ha −1 for fall-applied N, but in other straw-tillage treatments there was no effect of fertilizer timing. Cumulative fertilizer N recovery (plant + soil) over the 2 years averaged 64.2%, and was unaffected by straw-tillage treatment. Fertilizer N recovery, however, was less with fall-applied N (61.3%) than spring applied N (66.8%). At mid-season, fall plow treatments had higher soil inorganic N and inorganic N derived from fertilizer than spring plow treatments, apparently because of less immobilization. The fall plow treatments also retained higher inorganic N after harvest. Straw removal and fertilizer timing did not influence soil inorganic N and soil inorganic N derived from fertilizer. N removal in straw (16 kg N ha −1 yr −1) could deplete soil N in the long-term. Long-term effects of tillage timing on soil N will depend on the relative amount of N lost by leaching with fall plowing and that lost by denitrification under spring plowing. With direct seeding, crop yield and uptake of soil N was less, and N losses by denitrification could be greater. Application of N in spring, rather than fall, should enhance crop N uptake, reducing N losses and enhancing long-term soil organic N.

Seasonal changes of arbuscular mycorrhizal fungi as affected by tillage practices and fertilization : Hyphal density and mycorrhizal root colonization

The influence of tillage practices on native arbuscular mycorrhizal fungi (AMF) was studied in two, consecutive years in eastern Canada, in two 11 year-old long-term tillage-fertilizer experimental field soils, a sandy loam and a clay, growing corn in monoculture. The three tillage practices were: 1) conventional tillage (CT; fall plowing plus spring disking), reduced tillage (RT; spring disking) and no-till (NT). The corn crop received either inorganic (N and K) or organic (liquid dairy manure) fertilizers. Mycorrhizal hyphal density was estimated from soil samples obtained in early spring (before disking), at the 12–14 leaf stage, at silking, and at harvest. The percentage of corn root colonization by AMF at the 12–14 leaf stage, at silking and at harvest was also determined. The sandy loam was sampled over two consecutive seasons and the clay soil over one season.

Effect of Tillage and Rotation on Agronomic Performance of Corn and Soybean: Twenty-Year Study on Dark Silty Clay Loam Soil

In the U.S. Corn Belt, tillage without plowing was used on more than 50% of corn (Zea mays L.) and soybean (Glycine max (L.) Merr.] acreage in 1994, while no-till planting was used on about 30% of the acreage. Few research studies have evaluated these reduced tillage systems for 20 yr or more. This study includes plow, chisel, ridge, and no-till systems in continuous corn, corn after soybean, soybean after corn, and continuous soybean rotations. The experiment was conducted on Chalmers (fine-silty, mixed, mesic Typic Haplaquolls) silty clay loam soil in north-central Indiana for 20 yr. Objectives were to determine the effect of tillage and rotation on stands, growth, maturity, and yield of corn and soybean and to determine trends that develop with time for these variables. Major stand reductions occurred only in no-till continuous corn, 8% less than plowing. Compared with plowing, chisel and ridge tillage systems reduced growth and yield and increased harvest moisture by less than 3% in continuous corn. No-till reduced 4-wk height of continuous corn by 17%, yield by 14%, and increased harvest moisture by 2.1 percentage points compared with plowing. For corn following soybean, only no-till corn showed a yield reduction, 2.8%, compared with plowing. Twenty-year mean soybean yield reductions averaged 4 to 7% in both rotation and monoculture for chisel, ridge, and no-till systems compared with plowing. Relative yields for no-till continuous corn tended to be less than other tillage-rotation systems over time, while no-till soybean yields tended to improve with time, especially during the last 5 yr of the study. Both corn and soybean yields were better in rotation than in continuous cropping for all tillage systems. Of the tillage systems-rotation combinations in this study, only no-till continuous corn is likely to suffer major yield loss on a long-term basis on dark prairie soils of the Central and Northern Corn Belt.

The Impact of Rye Cover Crops on Weed Populations in a Tomato Cropping System

A reduced-till (RT) experiment determined the effect of rye seeding density and method of kill on rye biomass persistence, weed suppression, and tomato yield. ‘Wheeler’ rye was seeded at 56, 110, and 170 kg ha−1in the fall of 1988 and 1989 in Champaign, IL; Lexington, KY; and Lafayette, IN. One wk before transplanting tomatoes, rye was desiccated either by applying glyphosate at 1.1 kg ha−1and mowing (RT-glyphosate) or by mowing alone (RT-mowed). Both methods left rye residues on the soil surface as a mulch. Seeding density did not affect rye biomass, weed control, or tomato yield. Rye biomass differed depending on location and year, ranging from 320 to 1150 gm−2. Rye was completely killed by glyphosate, but regrew following mowing. RT-glyphosate suppressed weeds for 4 to 8 wk, which was similar to the suppression from conventional tillage (fall plowing with spring disking and harrowing) with trifluralin and metribuzin (CT-herbicide). Weed communities varied, but redroot pigweed and giant foxtail were present at all three locations. All treatments required supplemental weed management for commercially acceptable control. Except for IL in 1990, processing tomato yields (kg ha−1) in RT-glyphosate with hand-weeding were equal or better than yields in the CT treatments.

Long‐Term Effect of Five Tillage Systems on Corn Response and Soil Structure

AbstractTillage systems need to be compared over an extended period of time to determine their transitional and long‐term impacts on crop growth and soil properties. A 15‐yr experiment established in 1976 compared reduced tillage systems with conventional fall moldboard plowing for production of continuous corn (Zea mays L.) on a Maryhill silt loam soil (Typic Hapludalf). Corn plant growth and yield and soil properties were compared for five tillage systems: fall plow (fall mold‐board plow + spring secondary tillage), fall chisel plow (fall chisel plow + spring secondary), spring plow, spring plow/secondary (spring plow + secondary), and no‐till. No‐till consistently resulted in slower plant growth than most or all of the other tillage systems. The fall plow and spring plow/secondary treatments resulted in grain yields averaging 5% more than fall chisel plow, 9% more than spring plow, and 16% more than no‐till yields. From 1976 to 1983, no‐till yields tended to increase relative to fall plow; from 1988 to 1990, however, no‐till yields were much less than fall plow. No‐till resulted in the lowest proportion of aggregates <5 mm in diameter, highest bulk density, and greatest penetrometer resistance. Penetrometer resistance of the spring plow plots increased at a slower rate with depth than the fall chisel plow system. Among soil properties measured, the proportion of aggregates <5 mm in diameter was most often significantly correlated with yield.

Forage Legume-Small Grain Intercrops: Nitrogen Production and Response of Subsequent Corn

Frost-seeding a legume into an established stand of winter wheat (Triticum aestivum L.) or interseeding a legume into a small grain at planting has potential to provide the benefits of a legume green manure while still allowing for the harvest of a revenue-producing crop. Field studies were conducted at three Michigan locations to quantify N accumulation by alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) frost-seeded into winter wheat or interseeded with oat (A vena sativa L.) and to evaluate the response of a subsequent corn (Zea mays L.) crop to legume and fertilizer N. Cropping sequences included corn following either wheat, wheat frost-seeded with a legume, oat, or oat interseeded with a legume. Corn was planted either no-till following wheat or conventionally (moldboard plow) following oat. Frost-seeding and interseeding alfalfa and red clover had no effect on small grain yield, and stands of alfalfa and red clover were adequate (>13 plants/sq ft) even though N fertilizer had been applied to the small grains. Nitrogen accumulation did not differ among alfalfa or red clover cultivars, and averaged 80, 50, and 116 lb N/acre for alfalfa; and 96, 99, and 176 lb N/acre for red clover frost-seeded into winter wheat at the three locations. When interseeded with oat, alfalfa contained an average of 44 lb N/acre and red clover contained an average of 33 lb N/acre prior to fall plowing. Corn response to the frost-seeded legumes differed among locations due primarily to differences in precipitation during the weeks just prior to and following corn planting. When soil water was adequate, corn grain yields following the small grain seeded with a legume were 4 to 62% greater than following the small grain without the legume. With below-normal precipitation following corn planting, corn grain yields in the legume systems were reduced by 3 to 27%, primarily due to delayed and reduced emergence. Fertilizer replacement values based on grain yield ranged from 0 to 49 lb N/acre for alfalfa and from 0 to 113 lb N/acre for red clover. Response of corn to the preceding legume differed by year, location, and seeding method.