Mesic Typic Argiudoll Research Articles

Yield, Lodging, and Growth Characteristics in Sweet Corn as Influenced by Ethephon Timing and Rate

AbstractSummer storms frequently lodge sweet corn (Zea mays L.), making harvest difficult while reducing yields. Ethephon (2‐chloroethylphosphonic acid), a plant growth regulator, has the potential to be an anti‐lodging agent in sweet corn. Field research was conducted on a Plano silt loam soil (fine‐silty, mixed, mesic Typic Argiudoll) at the Arlington Research Station near Arlington, WI, in 1985 and 1986 to determine the effect of ethephon timing and rate on sweet corn. Four rates (0, 140, 280, and 420 g ha−1) of ethephon were applied at three application timings [tassel elongation (TE), TE + 4 to 6 d, and TE + 9 to 13 d] to two plant densities of ‘Jubilee’ sweet corn. In 1985, plant densities of 49 400 and 66 700 plants ha−1 were used. In 1986, an additional ethephon rate of 70 g ha−1 and plant densities of 59 200 and 73 900 plants ha−1 were used. In hand‐harvested plots, ethephon altered yield and plant growth both years. High rates of ethephon reduced lodging by 87%, plant and ear height by 16 and 13%, respectively, and increased brace root development by 50%. High plant densities increased yields 8% and lodging 23%. Timing of ethephon application on yield had variable results. Yields were reduced 13% with the high rate of ethephon at the early and middle application times, but were not altered at the late application time. When the potential for lodging is high, ethephon at the higher rates and late application times may be effective in preserving sweet corn yields.

Detachment of Soil as Affected by Fertility Management and Crop Rotations

AbstractAn experiment was initiated on Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudoll) in 1981 to compare the effects of fertility management and crop practices on splash detachment of soil. Experimental treatments included comparisons of crop rotations of soybean [Glycine max (L.) Merr.] after corn (Zea mays L.) (SB), corn after soybean (C), and oat/red and yellow sweetclover (Avena sativa L./Trifolium pratense L. and Mellilotus officinalis Lam.) after corn (O/CL). For each crop rotation, there were two management options, either added manure (OR) or herbicide plus chemical fertilizer (HF). The seventh treatment was continuous corn (CC) with herbicide, chemical fertilizer, and insecticide. Soil surface samples from each treatment were subjected to rainfall intensities of low (35 mm h−1), medium (62 mm h−1), and high (120 mm h−1). Total splash detachment of soil from simulated rainfall was linearly related to rainfall intensity. For all crop rotation treatments, total splash detachment generally was greater for manured soils than from soil with herbicides and fertilizer. Continuous corn had the lowest soil splash detachment at low intensity, second highest splash detachment at medium intensity, and the highest splash detachment at high intensity. This trend clearly indicated that rate of splash detachment of CC was higher than from soil under crop rotations. The splash detachment rates were 48, 40, 39, and 31 mg cm−3 for CC, C, SB, and O/CL, respectively. Treatment by rainfall intensity interaction was significant, which suggested that intensity and crop rotation were not independent in their effect on soil splash detachment. Soil aggregation as inferred from geometric mean diameter (GMD) indicated that CC had the lowest degree of aggregation (150) as compared to 211 for C, 225 for SB, and 313 for O/CL.

Chromosomal Locations of Genes for Traits Associated with Lodging in Winter Wheat

Lodging in wheat (Triticum aestivum L.) is a complex character which is influenced by morphological traits as well as environmental conditions. Wheat breeding programs would benefit from cytogenetic information on lodging and associated traits. Reciprocal substitutions between the hard red winter wheats, ‘Wichita’ and ‘Cheyenne’, for all chromosomes except Cheyenne 2B in Wichita were used to investigate additive and interactive effects of individual chromosomes on nine traits previously reported to be associated with lodging. Duplicate lines for each chromosome except Cheyenne 3B in Wichita were included to check background homogeneity. Straw strengths were measured by using an Instron universal testing machine (Instron Ltd., Canton, Ma) to break basal internodes of main tillers from plants grown in a field on a Sharpsburg silty‐clay loam soil (fine, montmorillonitic, mesic Typic Argiudolls) at Lincoln, NE, with a randomized complete block design. Data on the other eight traits (height, length and diameter of basal internodes, number and width of inner vascular bundles, width of culm wall, diameter of culm cavity, and width of tissue from epidermis through sclerenchyma layer) were collected from main tillers of a greenhouse planting with an augmented randomized complete block design. Wichita and Cheyenne differed significantly only in plant height and basal‐internode length among the nine traits. Substitutions of Cheyenne chromosomes into Wichita produced almost three times as many significant phenotypic changes as substitutions of Wichita chromosomes into Cheyenne. Reciprocal effects were obtained for chromosomes 3B (number of vascular bundles and culm‐wail width) and 3D (basal‐internode diameter). Each of the three Cheyenne homoeologous Group 4 chromosome pairs increased the number of vascular bundles in Wichita. Cheyenne chromosomes 3B and 6A each produced favorable effects in Wichita on several traits related to lodging resistance. Other Cheyenne chromosomes with major effects on single traits in Wichita were 5D for straw strength, 7A for plant height, and 2A for number of vascular bundles. The use of reciprocal substitution lines revealed reciprocal effects of homologues as well as interactions between substituted chromosomes and specific genetic backgrounds.

Nitrogen Fertilization and Plant Growth Regulator Effects on Yield and Quality of Four Wheat Cultivars

High rates of N fertilizer and the use of plant growth regulators (PGRs) to control lodging have combined to improve wheat (Triticum aestivum L.) yields in some studies and are often considered a part of intensive management systems. Our objective was to determine the effect of N rate and PGRs—chlormequat chloride (CCC) and ethephon—on soft red winter wheat yields, yield components, lodging, and baking and milling quality for flour characteristics under Indiana conditions. A split-split plot design was used with four soft red winter wheat cultivars—‘Arthur 71’, ‘Auburn’, ‘Caldwell’, and ‘Compton’—as whole plots; N rates 40, 80, 120, and 160 lb N/acre as subplots; and PGRs—CCC and ethephon—as sub-subplots. The studies were conducted on Parr silt loam (fine-loamy, mixed, mesic Typic Argiudolls). Cultivars varied in yield and yield components between the two years. Lodging was most severe with Arthur 71 and was minimal with Auburn both years. Nitrogen rates above 80 lb/acre were not beneficial in 1984. No yield response to N rates greater than 40 lb/acre occurred in 1985. N rates greater than 80 lb/acre increased lodging, decreased kernel size, and apparently reduced baking quality. Chlormequat chloride increased yields but only reduced lodging one year. Ethephon reduced lodging both years, but its detrimental effect on yield, kernel size, and baking quality detracted from its beneficial effect on lodging. Wheat yields were not increased when N rates were increased above recommended rates and PGRs were applied to control lodging.

Maize Yield Response Differences Between Moderately and Severely Eroded Illinois Soils

The primary objective of this study was to determine the impact of soil erosion on maize (Zea mays L.) yields for an array of soils selected to represent the diversity of soils in Illinois. Eight sites were located with slopes ranging from 3 to 14%. At each site, paired moderately and severely eroded phases of a soil series were located in the same field. The included soil series were Ava (fine-silty, mixed, mesic Typic Fragiudalf), Clarence (fine, illitic, mesic, Aquic Argiudoll), Grantsburg (fine-silty, mixed, mesic Typic Fragiudalf), Hoyleton (fine, montmorillonitic, mesic Aquollic Hapludalf), Parr (fine-loamy, mixed, mesic Typic Argiudoll), Rozetta (fine-silty, mixed, mesic Typic Hapludalf) (at two sites), and Tama (fine-silty, mixed, mesic Typic Argiudoll). Based on soil-boring observations, two to four 0.0025-acre plots were located within each of the moderately and severely eroded phases of a soil series. Maize was planted using a high level of management by either Illinois Agric. Exp. Stn. personnel or by participating farmers. The maize was harvested by hand, shelled, and moisture tested. A soil pit was dug within each eroded phase of all soil series and adjacent to each set of plots to sample and measure the chemical and physical characteristics of the soils. The soils chosen represent soils developed under prairie and forest vegetation, in deep loess, or in loess overlying fine- and medium-textured glacial till. Some of these soils have claypans (Hoyleton soils) or fragipans (Ava and Grantsburg soils). Soils formed in loess without root-restricting subsoils showed slight yield reductions of 9 bu/acre (5%) with increasing degree of erosion. Greater maize yield reductions of 26 bu/acre (24%) occurred when either loess-derived soils with root-restricting subsoils (claypans or fragipans) or soils developed in glacial till were eroded.

Seedling Root Development and Morphology of Cool‐Season and Warm‐Season Forage Grasses

A detailed description of grass seedli ng root morphology is essential to understand the differences in the establishment process among grasses. A repeated greenhouse study using a 1:1 mixture of Sharpsburg silty clay loam (fine, montmorillonit|c, mesic Typic Argiudolls) and coarse sand was conducted to determine root morphology differences at the third‐leaf stage among nine cool‐season forage grasses, creeping foxtail (A1opecurus arundinaceous Poir., reed canarygrass, (Phalaris arundinacea L.), smooth bromegrass (Bromus inermis Leyss.), tall fescue (Festuca arundinacea Schreb.), orchardgrass (Dactylis glomerata L.), russian wildrye (Elymus junceus Fish.), crested wheatgrass [Agropyron cristatum (L.) Gaertn.], intermediate wheatgrass [A. intermedium (Host) Beauv.], and western wheatgrass (A. smithii Rydb.); and nine warm‐season forage grasses, sideoats grama [Bouteloua curtipendula (Michx.) Tort.], blue grama [B. gracillis (H.B.K.) Lag. ex. Steud.], sand lovegrass [Eragrostis trlchodes (Nutt.) Wood], big bluestem (Andropogon gerardii var. gerardii) Vitman), sand bluestem [A. gerardii var. paucipilus (Nash) Fern.], little bluestem [Schizachyrium scoparium (Michx.) Nash], caucasian bluestem [Bothriochloa caucasica (Trin.) C.E. Hobb.], indiangrass [Sorghastrum nutans (L.) Nash], and switchgrass (Panicum virgatum L.). These grasses were selected as representative forage grasses of the northern USA. Andropogoneae species reached third leaf emergence 3 to 5 days earlier than other warm‐season grasses and 3 to 15 days earlier than cool‐season grasses. Most cool‐season grasses had no or little subcoleoptile internode elongation except Aveneae species. Aveneae species and warm‐season grasses, except Chlorideae species, had root development from the subcoleoptile internode. Sand bluestem had less subcoleoptile internode root development than big bluestem. Seminal root development was greater in species of the Triticeae tribe. Adventitious root development occurred by the three‐leaf stage on species of all tribes except for Andropogoneae members. Most grasses were in a juvenile period of root growth at third leaf emergence. Stage of root development did not coincide with stage of shoot development among species.

Quality of Whole Crop and Pressed Forage from Mechanically Dewatered Alfalfa, Red Clover, and Birdsfoot Trefoil

AbstractForage harvesting techniques that reduce losses in yield and quality that normally occur during field wilting of silage and curing of hay are needed. A 2‐yr field study was conducted to evaluate mechanical dewatering of first‐cutting forage of alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), and birdsfoot trefoil (Lotus corniculatus L.) harvested at four stages of maturity. Each species, grown on Plano silt loam soil (fine‐silty, mixed, mesic Typic Argiudolls), was harvested at weekly intervals beginning on 27 May 1980 and 26 May 1981, and the forage was macerated and pressed at 6.9 × 105 Pa for 2 min. Samples of the whole crop collected immediately after cutting and of the pressed forage were dried at 55°C to constant weight. Birdsfoot trefoil was the highest in N concentration of the three whole crops, and red clover was higher in N than alfalfa in 1 of the 2 yr. Pressed forage of alfalfa averaged 6.0 g kg−1 less N than the whole crop. Pressed forage averaged 106, 151, and 49 g kg−1 more neutral detergent fiber (NDF) than whole crop for alfalfa, red clover, and birdsfoot trefoil, respectively. Birdsfoot trefoil in vitro dry matter disappearance (IVDMD) was affected least by Pressing, and red clover IVDMD was affected most. Results of this 2‐yr experiment indicate that mechanical dewatering reduced IVDMD and generally N, and increased NDF concentration. Differences in legume species response to pressing were substantial and would preclude generalization of mechanical dewatering responses across species. However, whole crop dry matter, N, and IVDMD predicted 0.81 or more of the variation in pressed forage IVDMD of the three species, indicating that pressed forage IVDMD can be accurately predicted from whole crop composition.

Growth Regulator Effects on Wheat Culm Nonstructural and Structural Carbohydrates and Lignin1

Lodging can be a problem when wheat (Triticum aestivum L.) is grown using high rates of N in intensive management systems. The plant growth regulators (PGRs) chlormequat chloride (CCC) (2‐Chloro‐ethyl‐N,N,N‐trimethylammonium chloride) and ethephon [(2‐Chloro‐ethyl)phosphonic acid] often decrease lodging. Our objective was to determine the influence of CCC and ethephon on lodging and on carbohydrate and lignin composition of wheat culms. Water‐soluble carbohydrate (WSC) composition of the peduncle, middle, and lower internodes; and cellulose, hemicellulose, and lignin concentrations in cell walls of the middle and lower internodes were investigated in ‘Arthur 71’ (lodging susceptible) and ‘Auburn’ (lodging resistant) soft red winter wheat. Wheat was planted into a Parr silt loam (fine‐loamy, mixed, mesic Typic Argiudolls) in autumn of 1983 and 1984. Plants were fertilized with 45 and 180 kg N ha−1 and sprayed with CCC and ethephon the following spring. Arthur 71 had a higher lodging rating than Auburn, averaging 1.9 and 0.4, respectively (0.2 to 9 scale). Lodging increased as N fertilization rates were increased and decreased with the application of CCC and ethephon. Culm WSC concentrations averaged 20% higher for Arthur 71 than for Auburn. The low N application resulted in increased WSC concentrations (25% in the peduncle, 21% in the middle internode, and 42% in the lower internodes) compared to high N. Ethephon and CCC resulted in increased WSC concentration as compared to controls. Concentrations of cellulose, hemicellulose, and lignin in cell walls of the middle internode and lower internodes changed less than 5% when comparing cultivars, low N and high N, or controls and PGR‐treated plants. Lodging could not be associated with changes in concentrations of WSC in the culm or with changes in concentrations of structural carbohydrates and lignin in cell walls of the culm. The arrangement and interaction of the various structural carbohydrates and lignin in the culm cell walls may be more important in lodging resistance than concentrations of these components.

Nitrogen from Soybean for Dryland Sorghum1

AbstractCrop and soil data were collected for 2 yr (1984–1985) from a soybean [Glycine max (L.) Merr.]‐grain sorghum [Sorghum bicolor (L.) Moench] rotation experiment established in 1974, to evaluate the residual effects of soybean on N uptake, some agronomic characters, and yield of the sorghum crop and residual soil N accumulation. The soil at the experimental site was a Sharpsburg silt clay loam (fine, montmorillonitic, mesic Typic Argiudoll). Fertilizer rates of 0, 56, 112, and 168 kg N ha−1 were applied to the sorghum crop in both the continuous sorghum and rotation cropping sequences. Total N uptake by sorghum was significantly increased by rotation cropping (P<0.05) when the N fertilizer rate was 112 kg ha−1 or less. Sorghum grown in rotation or with the application of 56 kg N ha−1 or more flowered 6.1 days earlier than continuously grown sorghum without N. At the zero level of fertilizer N, sorghum after soybean yielded 85% more grain than did continuous sorghum. Rotation with soybean increased subsequent sorghum grain 14% compared to continuous sorghum when averaged over 2 yr. At or above the 112 kg N ha−1 level, differences between the cropping systems were not different. Estimates of residual soil N as NO−3−N in 1985 showed that after soybean there was 50 to 60 kg N ha−1 more than after continuous sorghum when 56 kg N ha−1 or less had been applied.

Planting Date and Tillage Effects on Corn Following Corn1

AbstractCrop residue remaining on the soil surface for erosion control under no‐tillage (NT) corn (Zea mays L.) production depresses early season soil temperatures compared to conventional tillage (CT). This has resulted in questions concerning planting date recommendations for NT in the northern United States. The objective of this study was to determine the influence of planting date on crop development and grain yield when corn produced under CT and NT follows corn. Conventional and no‐till systems were compared during 1983 to 1985 at Arlington, WI, on a Plano silt loam (fine‐silty, mixed, mesic Typic Argiudoll). Planting dates were 26 April to 6 May (early), 14 to 19 May (medium), and 27 May to 6 June (late). Plots were overplanted and stands were thinned to constant densities following complete emergence. Daily seed‐zone soil temperature and seedling emergence were measured. Colder soil temperatures under NT were associated with reduced corn emergence, delayed emergence and silking, and increased harvest grain moisture compared to CT, for early planting. With medium and late planting dates, differences between tillage systems for emergence and silk date were less pronounced or inconsistent between years, or both. For both tillage systems, highest grain yields were generally obtained when planting was completed by early May, with yield declining as planting was delayed. Decreased grain yields with NT or delayed planting, or both, were related to reduced cumulative air growing degree days between silk and the first 0°C frost. These results suggest that for corn following corn in northern U.S. regions, current recommendations for early planting under CT are applicable to NT. However, increased seeding rates may be required to overcome reduced emergence with NT systems.

Yield Accumulation, Leaf Area Index, and Light Interception of Smooth Bromegrass1

Smooth bromegrass (Bromus inermis Leyss.) is a cool‐season grass used extensively in the midwestern USA for spring and fall grazing. Smooth bromegrass has limited production in this region during the summer. This study was conducted to document the growth characteristics and yield accumulation of smooth bromegrass under various levels of N fertilizer. Live yield (dry matter yield of living herbage), leaf area index (LAI), light interception (LI), and crop growth rate (CGR) were determined on an established stand of ‘Lincoln’ smooth bromegrass grown on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudolls) in eastern Nebraska. Zero, medium, and high N levels were maintained at each growth period. Irrigated spring, summer, and fall growths of smooth bromegrass were sampled at 1‐ or 2‐week intervals in 1981 and 1982 depending on growth rate. Live yield, LAI, and CGR were all highest in the spring. Live yield reached a maximum of 10.3 Mg ha−1, CGR reached a maximum of 190 kg ha−1 day−1, and LAI reached a maximum of 6.8, which intercepted up to 99% of the incoming photosynthetic photon flux density during the spring growth period. Summer values for maximum live yield, LAI, and LI were 3.2 Mg ha−1, 4.1, and 73%, respectively. Maximum values of live yield, LAI, and LI for the fall growth period were 2.8 Mg ha−1, 5.2, and 97%, respectively. Smooth bromegrass has different growth and canopy characteristics at different seasons of the year. Growth models should consider seasonal differences in canopy characteristics as well as environmental parameters.

Seed Growth Characteristics of Soybean Genotypes Differing in Duration of Seed Fill1

Seed growth and development is an important part of the yield production process in grain crops. Experiments were conducted in the field for 2 yr to determine the seed growth characteristics of soybean [Glycine max (L.) Merr.] genotypes that varied widely the duration of seed fill. Fifty‐nine genotypes were grown in 1982 on a Donerail silt loam soil (fine, mixed, mesic Typic Argiudolls) and measurements of seed growth rate (SGR), final seed size (FSS), and effective filling period (EFP) were made. The 59 genotypes exhibited a wide range in SGR, FSS, and EFP. Although SGR and FSS were significantly correlated (r = 0.76**, significant at the 0.01 probability level), subsets of genotypes could be identified that exhibited a wide range in FSS with no variation in SGR. In 1983, seven genotypes (six plant introductions and one cultivar) were selected, on the basis of the 1982 data, to have a relatively similar SGR but a wide range in FSS and EFP. These genotypes were grown on a Maury silt loam soil (fine, mixed, mesic Typic Palendalfs). Fruit samples were taken at weekly intervals to characterize seed development. Cotyledon cell numbers were measured on selected cultivars in 1982 and 1983. For genotypes that differed in EFP, the patterns of dry matter accumulation and seed moisture changes with time were similar to those previously reported. The number of cotyledon cells per unit mass of seed decreased as FSS increased indicating that differences in cell size were associated with the differences in seed size in these genotypes. These data indicate that variation in FSS among genotypes can be associated with either variation in SGR and/or filling period duration.

Conservation Tillage and Irrigation Effects on Corn Root Development1

AbstractThe effects of conservation‐tillage practices on the root environment of corn (Zea mays L.) may differ with varying amounts of irrigation. Dryland, 50% irrigation, and 100% irrigation treatments were applied in combination with disc, no‐tillage, and a postemergence chisel treatment designed to allow rapid infiltration of irrigation water. The study was conducted during the 1980 growing season at the Nebraska Agricultural Experiment Station near Mead, NE, on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudolls). Root samples were taken to 1.50 m in 0.15‐m increments. Sampling was done at 60 (V8), 77 (V14), and 90 (R2) days after planting. Root length per soil volume as a function of depth from the soil surface was characterized using hybrid B73 × Mo17. Root length exhibited linear and often quadratic distribution over sampling depths at all sampling dates. The 100% irrigation treatment exhibited greatest total profile (0‐ to 1.5‐m) and surface (0‐ to 0.15‐m) root length at R2. Dryland and 50% irrigation treatments were associated with relatively greater root length proliferation deep in the soil profile. Differences in root length distribution were not as pronounced at stages V8 and V14. Chisel and no‐tillage treatments, with crop residues at the soil surface, resulted in greater surface (0‐ to 0.15‐m) and total profile root length than discing. Corn roots tended to explore the lower profile to a greater extent under water stress conditions. This phenomenon, in conjunction with soil water conservation by no‐tillage methods, may allow irrigators to increase water‐use efficiency by better use of stored soil moisture.

Composition of Leaf Protein Concentrate and Deproteinized Juice from Alfalfa, Red Clover, and Birdsfoot Trefoil1

AbstractLosses during field wilting of silage and curing of hay reduce both yield and quality. Direct harvest and mechanical dewatering avoid these losses and produce a protein concentrate. A 2‐year field experiment was conducted to evaluate legume species and harvest date effects on the yield and composition of the protein concentrate and deproteinized juice fractions from spring growth legume herbage. The soil was a Plano silt loam (fine‐silty, mixed, mesic Typic Argiudoll). Alfalfa (Medicago sativa L.) protein concentrate averaged 201 g dry matter (DM) kg−1 total mass, slightly higher than red clover (Trifolium pratense L.) and birdsfoot trefoil (Lotus corniculatus L.). Harvest date effects on DM concentration in both the protein concentrate and the deproteinized juice were significant but showed little relationship to shoot maturation stage. Alfalfa protein concentrate averaged 102 g N kg−1 DM, which was more N than the protein concentrate from red clover and birdsfoot trefoil in 1981 but not in 1980. Harvest date effects were small for alfalfa protein concentrate N concentration but red clover and birdsfoot trefoil had less of that constituent on the last harvest date. Total nonstructural carbohydrate (TNC) was highest in the deproteinized juice from red clover, which had 327 g TNC kg−1 DM, followed by birdsfoot trefoil and alfalfa with the lowest concentrations. Harvest date effects on TNC differed among species, but these differences were not large enough to be of practical importance. Alfalfa and red clover whole crops differed in the concentrations of several amino acids, but they differed less than the whole crop differed from the pressed forage and protein concentrate fractions within each species. Red clover protein concentrate had more threonine and valine than alfalfa protein concentrate but only 85% as much methionine, 52% as much cystine and less isoleucine. Results of this 2‐yr experiment indicate that N and DM concentrations differ in protein concentrates from different perennial legumes. Amino acid concentrations in protein concentrate were generally less affected by species and maturation than the same constituents in the whole crops. Species differences in deproteinized juice TNC concentrations were substantial and should be considered in the development of mechanical dewatering systems.

Nitrogen Management and Interseeding Effects on Irrigated Corn and Sorghum and on Soil Strength1

AbstractA 15‐yr experiment on Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudolls) investigated N management effects on corn (Zea mays L.) and grain sorghum [Sorghum bicolor (L.) Moench] grown side by side, under identical furrow‐irrigated conditions. Included were comparisons of anhydrous ammonia (AA) and N solution (UAN) as N sources, planting time (UAN‐PL) vs. summer sidedressing (UAN‐SD) application of the N, and rates of 90,180, and 270 kg N ha−1. Additionally, interseeding of rye (Secale cereale L.) into high N plots and alfalfa (Medicago sativa L.) into check plots of corn was accomplished at the time of ridging for furrow irrigation. The objectives were to evaluate the long term effects of varied management of the two N carriers and the interseedings on grain yields and N utilization, and the relative effects of these treatments on soil strength. Grain sorghum was the more productive crop under conditions of low N availability while corn responded to higher N rates, becoming the more economic crop with yields approaching 10 Mg ha−1 when N was plentiful. Yield increases averaged 5% greater for UAN‐SD over UAN‐PL, and AA was slightly more effective than UAN‐SD for both crops. Interseeded alfalfa and rye green manures provided average corn yield increases of 880 and 585 kg ha−1, respectively, explainable in part by improved N economy. No significant differences in penetrometer or vane shear tests were found between soils from AA and UAN‐SD plots, although there was a tendency toward lower soil‐strength values with both N carriers, relative to check plots.

Evaluation of Corn Growth and Productivity with Three Conservation Tillage Systems1

AbstractThis study was conducted to provide needed data comparing corn (Zea mays L.) growth and productivity for several conservation tillage (CT) systems. Such data will provide necessary information to better evaluate the economical potential of CT systems in the Northern Corn Belt. The tillage systems used in this study were till‐plant (TP), chisel (CH), no‐till (NT), and conventional (CN) tillage. The study was conducted on a Griswold silt loam soil (fine‐loam, mixed, mesic Typic Argiudoll) at Arlington, WI, and a Plainfield loamy sand soil (sandy, mixed, mesic Typic Udipsamment) at Hancock, WI, over a 3‐yr period. Final plant emergence and growth and yield parameters were measured. The final plant emergence was higher with the CT systems compared to CN at Arlington, while the final plant emergence of the NT system was lower than other tillage systems at Hancock. Plant height, leaf area, and dry matter per plant early in the growing season, for both locations ranked: CN > TP ≷ CH > NT, and in most cases were significantly different. However, at the end of the growing season, these growth parameters were not significantly different. Days from planting to 50% silking for the NT system were significantly delayed by 2 to 3 and 4 days at Arlington and Hancock, respectively. No‐till had the highest grain moisture content. Grain yields with CT systems were equal to or greater than CN tillage at both locations. No‐till grain yield at Hancock was 18% greater than CN when rainfall was below normal in 1983. Three‐year grain yield averages for the silt loam soil were 8.75,8.78,8.97, and 8.49 Mg ha 1 for CN, TP, CH, and NT, respectively. Three‐year grain yield averages for the loamy sand soil were 6.48, 6.48, 6.44, and 6.79 Mg ha 1 for CN, TP, CH, and NT, respectively. The results from this study showed no serious growth and yield reductions with CT systems compared to CN tillage in the Northern Corn Belt.

Wetting and Maturity Effects on Mineral Concentrations in Legume Hay1

AbstractWetting by rainfall during field drying of legume hay reduces forage yield and in vitro dry matter disappearance. Field experiments were conducted to evaluate wetting effects on mineral composition of alfalfa (Medicago sativaL.) and red clover (Trifolium pratenseL.) hay. Three and one‐half kg samples of each species, grown on Plano silt loam soil (fine silty, mixed, mesic Typic Argiudolls) and harvested at early and late maturity stages, were placed on wire screens and allowed to dry without wetting or were exposed to natural or artificial wetting in 1980 and 1981. A completely random design was used with three replicates in 1980 and two in 1981. In 1980, 25 mm of water was applied using sprinklers to hay wetted during drying. In 1981, hays wetted during and after drying were exposed to 41 and 62 mm of natural precipitation, respectively. Late maturity (fullto late‐bloom) forage was lower in P, K, Ca, Mg, and S than early maturity forage (early bud to first flower) of the same species. Artificially wetted and well cured hay did not differ significantly in concentrations of P, K, Ca, Mg, or S in 1980. Precipitation totaling 62 mm on dry early to late‐bud alfalfa hay reduced the K concentration from 28.1 to 15.5 g kg−1, indicating substantial leaching. The same treatment increased P concentration from 4.1 to 5.5 g kg−1, increased Ca from 13.0 to 19.7 g kg−1, and increased Mg from 4.2 to 5.0 g kg−1. Late‐bud and first‐flower red clover responded similarly when subjected to the same treatment. Late‐bloom alfalfa, exposed to 41 mm of precipitation during drying had 2.4 g kg−1of P, 15.9 g kg−1of K, 8.2 g kg−1of Ca, 1.9 g kg−1of Mg, and 1.6 g kg−1of S compared with 2.5,20.8, 11.5,2.5, and 2.2 g kg−1, respectively, for the same minerals in hay cured without wetting. Based on these data, the impact of wetting during hay curing on concentrations of P, Ca, Mg, and S was smaller than wetting effects on forage yield and in vitro dry matter disappearance. Wetting reduced K concentration to a greater extent than it reduced the other minerals studied. Alfalfa forage was consistently higher in S and lower in Mg than red clover forage of similar maturity.

Soybean Growth as Influenced by Planting Date, Cultivation, and Weed Removal1

AbstractKnowledge of weed interference is important for designing weed control systems for agronomic crops. Research was initiated to determine the critical periods of weed interference in soybean [Glycine max(L.) Merr.] and the minimum weed removal requirements needed to achieve optimum seed yields. In a field infested with mainly broadleaf weeds, a 4‐week weed‐free period after planting was needed to achieve optimum yields in early and late planted soybean grown on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudoll). Plots cultivated about 3 and 5 weeks after planting required only one handhoeing 2 weeks after planting to obtain optimum soybean yields. Weeds left 4 weeks before removal, but not 6 weeks, did not reduce soybean yields in early or late planted soybean. Results indicate that if soybeans are kept weed‐free the first 4 weeks after planting or if weeds are not left undisturbed longer than 4 weeks after planting, optimum soybean yields should occur.

Tillage and Low‐Pressure Center‐Pivot Irrigation Effects on Corn Yield1

AbstractLow‐pressure sprinkler irrigation systems have the potential to save energy, but also may aggravate soil‐ and water‐management problems. The objective of this research was to determine the influence of center‐pivot sprinkler irrigation method in combination with various tillage practices on corn (Zea mays L.) yield and yield components. A center‐pivot irrigation machine was redesigned to apply water by high‐pressure‐impact (HPI), low‐pressure‐impact (LPI), and low‐pressure‐spray (LPS) nozzles. Nozzles were sized and spaced to apply three different amounts of water: 100% (full irrigation), 75 and 50%. Three tillage treatments were used—till‐plant (T), disk (D), and till‐plant with chisel after last cultivation (C)—for each method and amount of water applied. The field study was conducted over a 4‐year period (1978 to 1981) on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudolls). Yields were influenced by the seasonal distribution and amount of precipitation, irrigation water applied, tillage, and the combined management inputs. The method of water application (HPI, LPI, and LPS nozzles) did not significantly (P > 0.10) influence grain yield. In 1979, the chisel tillage treatment produced significantly less grain than other treatments because severe root pruning limited stored water uptake during an extremely stressful period immediately following the chisel operation. No inherent differences in productivity were associated with low‐pressure center‐pivot‐sprinkler irrigation, or with various conservation‐tillage practices used in combination with reduced‐pressure‐sprinkler irrigation. Therefore, use of these practices can reduce production costs without reducing yield.

Multiple Cropping Soybean with Oats and Barley1

AbstractMultiple cropping and relay intercropping of soybean [Glycine max(L.) Merr.] with small grains was studied as an alternative cropping system or areas that are traditionally oriented towards production of feed for dairy cattle (Bosspp.). The objective was to evaluate multiple cropping of small grains harvested as forage and soybean harvested as seed in a dairy forage area of the north central United States. One oat (Avena sativaL.) cultivar, two barleys (Hordeum vulgareL.), and the soybean cv. Hodgson were grown in relay intercropping, double cropping, and sole cropping systems on a Plano silt loam soil (fine‐silty, mixed, mesic Typic Argiudoll) at Arlington, WI in 1977 and 1978. Relay intercropping systems were established by planting soybean into unthinned stands of small grains or by removing rows of small grains shortly after emergence and later planting soybean in the gaps. Double‐cropped soybean was planted after barley and oats were harvested as forage. Early soybean checks (sole cropping) were planted on the same date that relay intercropped soybean was planted, and late soybean checks were planted on the same date that: double‐cropped soybean was planted. Soybean row widths in all systems were 0.41‐, 0.75‐, and 0.90‐m. Early soybean checks were more productive than soybean relay intercropped in both thinned and unthinned stands of oats and barley, but late soybean checks were not always more productive than double‐cropped soybean. Yields of soybean relay intercropped in 0.45‐m rows were higher in thinned stands of barley and oats than in unthinned stands. Differences were not as large in wider rows. Cultivar differences in forage yield were not associated with consistent differences in yields of relay intercropped and double‐cropped soybean. The most productive cropping sequence was a double‐cropping system that had a forage yield of 4.93 Mg ha‒1and a soybean yield of 2.21 Mg ha‒1.