bluuebunny/crossref_metadata_2025 huggingface dataset:
Forage Yield of Intercropped Corn and Soybean in Various Planting Patterns1
Authors: Herbert S. J. , Putnam D. H. , Poos‐Floyd M. I. , Vargas A. , Creighton J. F.
Published: July 2010

Corn (Zea mays L.) and soybean (Glycine max L. Merr.) were intercropped in various planting patterns in 1980, 1981, and 1982 on a Hadley fine sandy loam (coarse‐silty, mixed, nonacid, mesic Typic Udifluvent) to determine if corn:soybean mixtures might provide silage superior to pure corn for ruminants. All but one of the intercrop planting patterns produced dry matter (DM) yields similar to corn monoculture in the 1st year even when as many as half the corn rows were replaced with soybean. All intercrop planting patterns in 1981 produced similar DM yields to corn monoculture, but in 1982 intercrop DM yields were significantly lower than corn monoculture DM yields. Dry matter yields per row of intercropped soybeans were 6 to 32% less than yields per row of soybeans in monoculture. However, the DM yield per row of intercropped corn was increased 21 to 53% compared to yield per row of monoculture corn and compensated for the reduced DM yield of soybean. Yields for monocultures were computed at various proportions of corn and soybean in the harvested mixture and compared with intercrop yields. All intercrop patterns produced more DM than would be obtained from monocultures at the same yield‐ratio as in the intercrop. Protein Concentration was increased from 69 to 81 g kg−1 for corn monoculture to 88 to 108 g kg−1 for the various intercropping patterns. All intercrops produced 8 to 17% more total protein ha−1 than corn monoculture. The intercrop pattern where alternate corn rows were replaced by soybean rows produced the largest increases in protein concentration although DM yield was reduced by 14% in the 3rd year.
Partition of Mg in Forages as Affected by Fertilization, Species, Growth Stage, and Sample Preparation1
Authors: Shockey W. L. , Reid R. L.
Published: July 2010

A 2‐year study was conducted in order to study the chemical form of Mg in different grass and legume species that are commonly used for livestock feeding in the Northeastern United States. Orchardgrass (Dactylis glomerata L.), tall fescue (Festuca arundinacea Schreb.), and alfalfa (Medicago sativa L.) were treated with magnesium sulfate (MgSO4. 7H2O) and dolomitic limestone (CaCO3.MgCO3) at 280 kg Mg ha−1, or with no Mg fertilizer. The soil was a fine, loamy, mixed, mesic Hapludalf. Grass species received 34 or 224 kg N ha−1 as NH4NO3. In the 1st year samples were taken at four growth stages, prepared as fresh, oven‐dried or freeze‐dried herbage and partitioned into acetone soluble, water soluble, and acetone and water insoluble fractions. In the 2nd year samples were taken at two growth stages and prepared as fresh material only. Fertilization with MgSO4. 7H2O increased (P<0.01) total Mg concentrations in herbage compared to CaCO3. MgCO3 and no Mg treatments. High N fertilization of the grass species increased (P<0.01) total Mg levels compared to low N treatments. Magnesium as percent total Mg in each chemical fraction was affected (P<0.05) by forage species, stage of maturity and method of sample preparation and ranged from 0.7 to 24.8% (x̄ = 6.7%) for acetone soluble, 42.8 to 82.3% (x̄ = 65.7%) for water soluble, and 15.5 to 42.9% (x̄ = 27.6%) for acetone and water insoluble Mg fractions over all treatments. The proportion of total Mg in the water soluble fraction was higher (P<0.05) at mature growth stages for alfalfa and tall fescue compared to orchardgrass and the proportion of Mg extractable with acetone was less (P<0.0001) for dried compared to fresh sample preparations. Although fertilizer treatments affected total herbage Mg concentrations, there was no apparent effect of fertilization upon the chemical form of Mg in the plant.
Standard and Cool Germination Tests Compared With Field Emergence in Upland Cotton1
Authors: Smith C. Wayne , Varvil J. J.
Published: July 2010

Standard germination, defined as percent of healthy seedlings reaching 38 mm after 7 days at 30°C is the primary, and in most cases only, information defining planting seed quality of upland cotton (Gossypium hirsutum L.) to producers. However, this percentage reflects only the emergence potential when seed are planted during optimum field conditions. An additional germination test conducted at 18°C has been advocated as a vigor test to aid producers in selecting quality planting seed. This study was undertaken to determine if the 18°C vigor test would identify variation in planting seed quality when the standard germination test indicated acceptable quality. All seed lots were fungicide‐treated remnant seeds from the Univ. of Arkansas cultivar testing program. Standard and 18°C germination tests were conducted as outlined by the Association of Official Seed Analyst. Field plantings were made in randomized complete block designs with four replications on 17 Apr. and 29 June 1979 and 24 Apr. and 27 May 1980. Test sites were Memphis silt loam ( a fine‐silty, mixed, thermic Typic Hapludalf) in 1979 and Henry silt loam (a coarse‐silty, mixed, thermic Typic Fragiaqualf) in 1980. Percent emergence was recorded after 2 weeks. Data indicated that seedlots having 30°C germination ≥ 80% and 18°C germination < 50% should not be planted when low temperature stress is likely. Although clear distinctions were not evident, 18°C germination ≥ 60% appears to indicate acceptable to excellent quality.
Modification of Cotton Water Relations and Growth with Mepiquat Chloride1
Authors: Stuart B. L. , Isbell V. R. , Wendt C. W. , Abernathy J. R.
Published: July 2010

Manipulation of crop architecture through the use of chemical bioregulators suggests the potential to improve plant water use and production efficiency. A bioregulator, mepiquat chloride (1,1‐dimethyl piperidinium chloride), was evaluated in field grown cotton (Gossypium hirsutum L.) during 1979, 1980, and 1981 to determine effects on several plant water relations parameters and crop development in a semiarid environment. All experiments were conducted on an Olton loam soil (fine, mixed, thermic family of Aridic Paleustolls). A broadcast, foliar application was made at the rate of 50 g active ingredient (a.i.)/ha during the early square (young floral bud) Stage. Increases in leaf water potential (Ψw), solute potential (Ψw), and turgor pressure (Ψp) in mepiquat chloride treated plants were recorded during midmorning and at daily minimum Ψw. The earliest Ψw increase wass measured 12 days after application. Changes in Ψw ranged from no significant differences to a 0.63 MPa increase in treated plants, 77 days after application under a high soil water level. Increased Ψs and Ψp in treated plants occurred most frequently during the midmorning period and increases Of 0.20 MPa were measured. Improvements in plant water status were not restricted to low soil water availability and occurred across a range of control Ψw from −1.43 to −3.43 MPa. Increased abaxial transpiration rate, associated with decreased diffusive resistance, was measured in treated plants, particularly during the afternoon. No difference in seasonal soil water extraction was measured between treatments, even in tests in which leaf area index (LAI) was reduced 33% by mepiquat chloride application. Leaf area index reductions were attributable to both fewer leaves per plant and reduced leaf size. Differences in the growth parameters between treated and untreated plants were most evident when conditions for growth were optimum. A maximum decrease in plant height of 25 cm was measured 43 days after application in a high soil water level experiment. Reductions of one to two mainstem nodes were measured in treated plants. The number of bolls per plant throughout the season was not altered by mepiquat chloride application, and there were no differences in lint yield as a result of treatment.
Initial Mowing of Kentucky Bluegrass‐Perennial Ryegrass Seedling Turf Mixtures1
Authors: Brede A. D. , Duich J. M.
Published: July 2010

Mixtures of turf‐type, perennial ryegrass (Lolium perenneL.) and Kentucky bluegrass (Poa pratensisL.) are desirable for lawn plantings because they combine a uniform appearance with genetic diversity. Attaining a balanced mixture of these two grasses is difficult because of the vigorous seedling growth of ryegrass, relative to blue‐grass. The purpose of this study was to evaluate the effects of close mowing of a Kentucky bluegrass‐perennial ryegrass seedling stand on the establishment and development of the turf. A field trial was established which contained mixtures and monocultures of both species, planted on Hagerstown silt loam (a fine, mixed, mesic Typic Hapludalf) in University Park, Pa. Kentucky bluegrass was generally more prevalent where close mowing treatments were used shortly after emergence. After 2 months of growth, a stand seeded at 95% bluegrass (pure‐live‐seed count) contained 49% bluegrass shoots when mowing began on Week 3 (the 3rd week after sowing) at a height of 3.8 cm, 66% bluegrass when mowing began on Week 3 at 1.3 cm, and 84% bluegrass when mowing began on Week 2 at 1.3 cm. Kentucky bluegrass was optimally favored by the commencement of mowing at 2 weeks after planting (approximately 9 days after the first noticable emergence of the ryegrass). This date coincided with a 50% foliar ground cover in the unmowed, mixed stand. Plots mowed initially at 3.8 cm required at least 95% Kentucky bluegrass in the seed mixture to produce a 50:50 mixture of the two species at 2 months. Plots mowed at 1.3 cm, 2 weeks after planting, needed only 50 to 75% bluegrass seed in the mix to achieve the same result. The shoot density, shoot size, and the leaf area index (LAI) of Kentucky bluegrass in mixed stands tended to decrease with an increase in the initial height of cut and/or the weeks until first mowing, while the density and size of perennial ryegrass shoots tended to increase. No observable injury (e.g., discoloration or scuffing damage) was caused by the close, early mowing treatments. Monocultures received no appreciable benefits from the close, early mowing treatment. Mowing of monocultures should begin as soon as the seedlings exceed the height intended for the mature stand.
Plant‐Available Sulfur as Measured by Soil‐Solution Sulfate and Phosphate‐Extractable Sulfate in a Ultisol1
Authors: Hue N. V. , Adams Fred , Evans C. E.
Published: July 2010

Because S deficiency in young small grain plants is not uncommon on limed, sandy Ultisols, a method predicting S requirement for the plants is needed. A greenhouse study was conducted to determine the effects of S at different pH levels on wheat (Triticum aestivumL.) growth, S concentration of plant tissue, soil‐solution sulfate (SO42−), and phosphate [Ca(H2PO4)2]‐extractable SO42−. A Benndale loamy sand surface soil (coarse‐loamy, siliceous, thermic Typic Paleudult) was treated with three lime rates (0,5.6, and 8.1 mmol kg−1) and four gypsum rates (0,10, 20, and 40 mg S kg−1for the first two lime levels and 0,8,16, and 32 mg S kg−1for the highest lime level). Plant tissue samples were taken 5,9,13, and 17 weeks after planting, and soil samples were taken at planting and 9 and 17 weeks later. There was a yield response to S at each harvest, regardless of soil pH. Yield and S uptake were both highly correlated with soil‐solution SO42−concentration and with Ca(H4PC4)2‐extractable SO42−. As a result of plant uptake, soil‐solution 42−decreased after each harvest, with the greatest redaction occurring at the highest lime rate. Sulfur mineralization from organic matter provided significant 42−to plants in low‐S treatments, and some added SO42−became nonextractable at high S rates. Minimum SO42−concentrations for maximum wheat growth was 0.25 mMin soil solution and 6.0 mg S kg−1in Ca(H2PO4)2extract. Minimum S concentration in plant tissue for maximum dry matter yield was 1.6 g kg−1.
Drying Rates of Standing Compared to Windrowed Wheat1
Authors: Clarke John M.
Published: July 2010

Little information is available to support the practice in the northern USA and Canada of windrowing wheat to accelerate grain drying. Drying rates of standing and windrowed wheat (Triticum aestivumL. and T. turgidumvar. durumL.) were compared at three locations in western Canada in order to assess the efficacy of windrowing in accelerating the wheat harvest. The soil was an Aridic Haploboroll. The time taken for wheat windrowed at recommended kernel water concentrations of 430 to 540 g water per kg kernel dry weight to reach a safe water concentration (170 g kg−1) for combining was compared with the time taken for the standing crop to reach this point. In 40 station‐years data, windrowed wheat dried from 6 days faster to 1 day slower than standing wheat. In all but 4 station‐years, windrowed wheat dried 0 to 2 days faster than standing wheat. Under hot, dry conditions, drying rates of both standing and windrowed crops were very rapid, with a 0‐ to 1‐day spread in drying time. When crop maturity was uneven and drying conditions less favorable, windrowed wheat reached the combining stage up to 6 days faster than standing wheat. Wet conditions during harvest caused slower drying of windrowed than of standing wheat. Light rains tended to cause greater increases in kernel water concentrations of standing than of windrowed wheat. Straw dried faster than kernels in windrowed crops, but slower than kernels in standing crops.
Grain and Forage Yields of Irrigated Second‐Crop Corn Seeded on Five Planting Dates1
Authors: Widstrom N. W. , Young J. R. , Martin W. K. , Shaver D. L.
Published: July 2010

Corn (Zea mays L.) is a widely‐grown summer crop in the United States. Where the growing season is of sufficient length, a second crop can be accommodated. This study identifies the optimum planting date and best of seven experimental hybrids for second crop grain and forage yields. The experimental hybrids with subtropical germplasm and/or heat tolerance were evaluated for five planting dates on a Typic Paleudult in seven to eight replications for 2 years. Previous studies considered fewer hybrids over a narrow range of planting dates. Among our plantings ranging from 1 June to 1 August, the 1 June planting achieved the maximum forage yield of 42.0 Mg ha−1 while a mid‐June planting gave an optimum grain yield of 4.40 Mg ha−1 when averaged over both years. The heat‐tolerant hybrids, C6862 and C7867, produced about two‐thirds the yields of other hybrids during 1981 with below normal growing conditions but in 1980 were fully competitive with the five hybrids having tropical germplasm when excessive heat, moisture much below normal, and insect pressure prevailed during the summer growing season. Significant interactions between hybrids and planting dates occurred for grain yields in 1980 and for grain and forage yields in 1981. The best average grain and forage yields of 4.43 and 38.5 Mg ha−1, respectively, were produced by X5802. Forage yields were much more consistent than grain yields when viewed over years or hybrids. To maximize the probability of success, summer plantings of corn should be made as early as possible, and an option to harvest as forage should always be maintained to prevent losses when adverse weather conditions suppress grain yields.
Evaluations of the Potential of Hyacinth Bean as an Annual Warm‐Season Forage in the Mid‐South1
Authors: Fribourg Henry A. , Overton Joseph R. , McNeill Walker W. , Culvahouse E. W. , Montgomery Monty J. , Smith Marshall , Carlisle R. J. , Robinson N. W.
Published: July 2010

Hyacinth bean (Lablab purpureus (L.) Sweet) or lablab bean, a short‐lived perennial legume in the tropics, is widely cultivated in many parts of the world. Although the potential of hyacinth bean as a forage crop has been recognized in Brazil, Australia and elsewhere, its possible use in North America has received little attention. A series of trials was started in 1974 to ascertain the potential value of ‘Tift‐1’ hyacinth bean as a warm‐season annual forage in a region with a humid mesothermal climate, when grown on well‐drained soils such as Memphis silt loam (fine‐silty, mixed, thermic Typic Hapludalfs) at elevations of 300 m or less. The dry matter forage produced during hot dry weather ranged between 2 and 5 Mg ha−1. The concentrations of crude protein, and of acid‐ and neutral‐detergent fibers, were at an acceptable level for a forage legume. The forage produced was very leafy in both the first growth and in the regrowth stages after cutting or grazing. Regrowth took place when a stubble of 10 cm was left. Hyacinth bean was established easily in either broadcast or row arrangements on prepared seedbeds, using 20 to 25 kg of seed ha−1, or with no‐till methods. Trailing vines rapidly covered interrow spaces. Hyacinth bean was susceptible to feeding by bean beetles (Epilachna corrupta), but was tolerant of the insecticide carbaryl (1‐naphthyl methylcarbamate) as well as of the herbicide trifluralin (α,α,α‐trifluoro‐2,6‐dinitro‐N,N‐ dipropyl‐p‐toluidine). Over 900 kg ha−1 of clean Tift‐1 hyacinth bean seed were produced. Dairy cattle refused to consume hyacinth bean in two trials, but beef cows and calves grazed it readily in five different location‐ year trials. Calves creep‐grazing hyacinth bean gained 840 g day−1 during a 90‐day grazing season begun in early July. Hyacinth bean, an annual in the mid‐South, appears to have considerable potential as a pasture for growing animals during hot, dry periods.
Effect of Ploidy on Yield and Quality of Pearl Millet × Napiergrass Hybrids1
Authors: Hanna W. W. , Gaines T. P. , Gonzalez B. , Monson W. G.
Published: July 2010

The highly male and female sterile triploid pearl millet [Pennisetum americanum (L.) Leeke) × napiergrass (P. purpureum Schum.) interspecific hybrids produce high yields of high quality forage. Colchicine induced hexaploids are male and female fertile and morphologically resemble the triploids. However, information concerning the effects of increased ploidy on agronomic, quality, and elemental factors of the forage is limited. In 1979 and 1980, triploid and hexaploid clones of several interspecific hybrids were established in the field on a Fuquay soil (loamy, siliceous, thermic Arenic Plinthic Paleudults) and evaluated for dry matter yield, concentrations of dry matter, in vitro dry matter disappearance (IVDMD), crude protein, total sugars, cell wall, and the elements P, K, Mg, Ca, Mn, Zn, Fe, and Cu. Triploids on the average had higher dry matter yields, and dry matter and protein concentrations than hexaploids. At anthesis, 3x plants were equal to or higher than 6x plants while at the vegetative stage 6x plants were generally higher than or equal to 3x plants in IVDMD. No differences were observed between 3x and 6x plants for total sugars and cell wall. Significant differences for elemental concentrations between ploidy levels were observed in 1980 for P (6x>3x), K (6x>3x), and Fe (3x>6x). These differences were not consistent for all clones. Increased ploidy from 3x to 6x in thisstudy generally had a neutral or negative effect on the characters studied. Triploids have the potential to produce higher yields of higher quality forage than hexaploids.
Wind and Sandblast Injury to Field Crops: Effect of Plant Age1
Authors: Armbrust D. V.
Published: July 2010

Most plant sandblast studies have been conducted with plants at only one age, which has varied from 3 to 21 days after emergence, depending on the plant species. This study was designed to determine if age of plants exposed to sandblast injury influences severity of damage. Plants of ‘RS‐626’ grain sorghum [Sorghum bicolor (L.) Moench.], ‘Williams’ soybean [‘Glycine max’ (L.) Merr.], and ‘Parker’ winter wheat (Triticum aestivum L.) were exposed in a wind tunnel to a wind velocity of 13.4 m/s for 80 min and wind plus sand (0.297 to 0.42 mm diam) for 10, 20, 40, and 80 min at 3, 7, 14, 21, and 28 days after emergence and vernalization. Maximum reduction in dry weight measured 14 days after exposure and delay in appearance of first inflorescence or bloom occurred when plants were exposed 7 to 14 days after emergence, except for winter wheat exposed after vernalization where dry weight was not affected and inflorescence delay was greatest when exposed 21 days after vernalization. Spike weight and number in winter wheat were not affected by fall exposure but were reduced by exposures which occurred 2 to 4 weeks prior to spike emergence. The results indicate the need for cultural practices which will control wind erosion throughout the growing season for maximum crop yields.
Photosynthesis and Transpiration Responses of Soybean Canopies to Short‐and Long‐Term CO2 Treatments1
Authors: Jones Pierce , Allen L. H. , Jones J. W. , Valle R.
Published: July 2010

The purpose of this investigation was to determine whether long‐term adaptation to CO2 pretreatment affects canopy response to short‐term CO2 treatments. Soybeans [Glycine max (L.) Merr. cv. Bragg] were grown in outdoor controlled environment chambers from seedling onwards at 330 and 800 μmol CO2 per mole air. After 68 days, the CO2 treatment levels were temporarily reversed for 5 days. Before the step change in CO2 concentrations, CER at high light in elevated CO2 treatments was 85% greater than in ambient treatments. After the reversal, canopies in the newly enriched chambers had CO2 fixation rates 75% greater than in the chambers that were switched to ambient CO2 concentrations. Furthermore, the CER responses to PAR were similar whether the canopy was acclimated or newly exposed to the particular CO2 level. Before treatment reversal, transpiration rates were essentially equivalent in the two treatments. Stomatal resistances of leaves were higher in elevated CO2, but the acclimated enriched canopies had developed additional leaf area resulting in similar total canopy resistances to transpiration. After reversal, absolute water use declined by 18% in the canopies with CO2 increased from 330 to 800 μmol mol−1 and increased by 36% in the canopies with CO2 decreased from 800 to 330 μmol mol−1. It was concluded that short‐term exposure to different CO2 treatments adequately estimated long‐term canopy CER response to CO2 level, but did not adequately predict long‐term canopy transpiration response.
Nitrogen‐ and Water‐Use Efficiency of Several Cool‐Season Grasses Receiving Ammonium Nitrate for 9 Years1
Authors: Power J. F.
Published: July 2010

Comparative information is needed on differences between grass species regarding dry matter production, root growth, water use, and response to N fertilization, as affected by both age of stand or years of N fertilization. The research reported here was conducted on a Temvik silt loam (fine‐silty, frigid, mixed Typic Haploboroll) at Mandan, ND. Ammonium nitrate was surface broadcast at 0, 45, or 225 kg N/ha for 9 years on established stands of western wheatgrass [Pascopyrum smithii Rydb. (Love)], crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schult.], intermediate wheatgrass [Elytrigia intermedia (Host) Nevski], smooth bromegrass (Bromus inermis Leyss.), Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski], green needlegrass (Stipa viridula Trin.), and Garrison creeping foxtail (Alopecurus arundinaceus Poir). Dry matter production was usually greatest for E. intermedia. Production for B. inermis, P. smithii, and A. desertorum averaged 85 to 90% that of E. intermedia, and about 65 to 72% for the other species. Dry matter production for all species was generally doubled by 45 kg N/ha, and increased three‐to fourfold with 225 kg N/ha. At 45 kg N/ha, N‐use efficiency varied from an average of 51 kg dry matter per kg N for E. intermedia to 22 for Ps. juncea. Corresponding values at 225 kg N/ha dropped to 16 and 12 kg/kg N. Root dry weights were generally increased 50 to 100% by both N rates, but consistent differences among species were not evident. Annual water use was increased about 20 mm by fertilization, except in extreme drought years. Water‐use efficiency (WUE) was also increased about threefold by fertilization, ranging from 22.6 kg/mm for fertilized E. intermedia to 3.2 for nonfertilized Al. arundinaceus. Water‐use efficiency was highly correlated with dry matter production, increasing about 2.8 kg/mm for each 1000 kg/ha increase in production, with no effect of species, time, or N fertilization.
Sensitivity Analysis of the Parameters of a Mechanistic Mathematical Model Affected by Changing Soil Moisture1
Authors: Barber S. A. , Mackay A. D.
Published: July 2010

Sensitivity analyses are useful for evaluating the effects of changes in soil and plant properties on plant nutrient uptake. The objective of this study with corn (Zea maysL.) was to determine the influence on P and K uptake of changes in root growth rate, k, mean root radius, ro, and effective diffusion coefficient, De, that resulted from changing the level of soil moisture (volumetric moisture contents of 0.22 (M0), 0.27 (M1), and 0.32 (M2)) of three soils differing in available P and K. The data used were obtained in a controlled‐climate chamber study. Increases in De, which resulted from raising soil moisture, only explained 27 to 32% and 11 to 27% of the total calculated increase in P and K uptake, respectively, across the three soils as moisture was raised from M0to M1. In contrast, the increase in k, which resulted from raising soil moisture, explained 50 to 56% and 46 to 69% of the total calculated increase in P and K uptake, respectively, as moisture was raised from M0to M1. This emphasized the importance of root growth in providing the plant with an adequate supply of nutrients. The results highlight the significance of soil moisture in plant growth and demonstrate the advantages of using the modeling approach to furnish data on the effects of moisture on each of the mechanisms involved in nutrient uptake.
Nitrogen Requirements of Potatoes1
Authors: Westermann D. T. , Kleinkopf G. E.
Published: July 2010

Nitrogen fertilizer applications, for maximum fertilizer efficiencies and crop yields, should be based on the N required by the crop during its various growth stages. The objectives of this paper were to identify the N requirements of the potato plant (Solanum tuberosumL.) during growth and to evaluate selected soil and plant tissue tests as indicators of the plant's N status. Growth analysis data and soil and petiole NO3‐N concentrations were obtained at predetermined time intervals from N fertilization treatments in replicated field studies on a coarse‐silty mixed, mesic Durixerollic Calciorthrid soil. Maximum early tuber growth occurred when leaf area index was between 2.5 and 3.2 and the tops contained between 79 and 100 kg N ha−1at the start of linear tuber growth. A preplant N fertilizer application between 67 and 134 kg ha−1gave these characteristics under the experimental conditions. The maximum dry matter production rate per day (approx. 250 kg ha−1) occurred when there was between 80 and 140 kg N ha−1in the plant tops and roots. An average tuber growth rate of 0.75 Mg ha−1day−1required a N uptake rate of 3.7 kg ha−1day−1to prevent the loss of N and dry matter from the tops and roots. Sufficient N was available for this rate when the soil NO3‐N concentration was > 7.5 mg kg−1(0.46‐m soil depth), corresponding to 15 000 mg kg−1NO3‐N in the fourth petiole. Soil and petiole NO3‐N concentrations may be used to adjust the N fertilization rates during the growing season. This practice has the potential of increasing the overall N fertilizer use efficiency and final tuber yields within the climatic, disease, and variety limitations.
Evaluation of Three Wetting Agents as Soil Additives for Improving Crop Yield and Nutrient Availability1
Authors: Wolkowski R. P. , Kelling K. A. , Oplinger E. S.
Published: July 2010

The effect of soil applications of WEX, Basic H, and Amway Spray Adjuvant was evaluated using corn (Zea maysL.), soybean [Glycine max(L.) Merr.], or potato (Solanum tuberosumL.) as test crops at three Wisconsin locations. Each wetting agent is a nonionic surfactant, and claims or has claimed to improve crop yield, quality, and nutrient availability. WEX was evaluated at recommended fertilization levels. Amway and Basic H, in the corn experiments, were evaluated at varying levels of applied N. Basic H was evaluated on potatoes at 30, 50, and 100% of the entire recommended fertilization program. Although crop yield was increased by fertilization in all cases, no yield improvements were observed from the use of any wetting agent at any fertilizer rate. No differences in nutrient availability as evidenced by foliar nutrient content of N, P, and K or crop protein levels were observed in association with the application of a wetting agent.
Root Damage by Western Corn Rootworm and Nutrient Content in Maize1
Authors: Kahler A. L. , Olness A. E , Sutter G. R. , Dybing C. D. , Devine O. J.
Published: July 2010

Little is known about the effects of root pruning by insects on nutrient content of maize (Zea maysL.). The objective of this study was to evaluate root damage effects caused by western corn rootworm (WCR, Diabrotica virgifera virgiferaLeConte) larval feeding on Fe, Na, K, Ca, Mg, and N contents in shoots and seeds of maize hybrid ‘Pioneer 3978’. The experimental design was a randomized complete block, and treatments included applications of 0, 1000, 2000,4000, and 8,000 WCR eggs per lineal meter of row in 1982 and 0,4000, and 12 000 WCR eggs per lineal meter of row in 1983. Maize seeds were planted ca. 23 cm apart in Brookings sicl (pachic Udic Haploborolls) soil. Aboveground plant samples were collected before intense larval feeding and after adult beetle emergence. These shoot samples and grain harvested at maturity were weighed and analyzed for their nutrient content. Severe root pruning decreased shoot dry weight and reduced grain yields at harvest by 13.5% in 1982 and by 9.7% in 1983. Contents of K, Mg, and Ca decreased and Fe and Na contents increased in shoots in 1982, but were not affected by root pruning in 1983. Accumulation of Na and Fe in shoots was attributed to compensatory branch root growth at critical stages of plant development. Root pruning may have caused new root development or branching into parts of the soil where Fe and Na could be obtained. Grain yield and grain Na content were related directly to the amount of root pruning in 1982. In 1983, grain yield was reduced and element content was altered by root pruning, but not in a simple linear manner. The results suggested that further studies of root pruning by WCR larvae of additional hybrids and their inbred parents may aid identification of elemental functions for maize.
Phosphorus Fertilization in No‐Tillage Corn Production1
Authors: Eckert D. J. , Johnson J. W.
Published: July 2010

The use of no‐tillage crop production as a water quality management practice may be complicated by a tendency for phosphorus (P) to accumulate at or near the soil surface under no‐tillage conditions. Little work has been published to define best management strategies for P in no‐tillage situations, either from fertilization or water quality standpoints. In this study, P was applied to no‐tillage corn (Zea maysL.) by surface broadcasting or subsurface banding, to a Wooster silt loam (fine‐loamy, mixed, mesic Typic Fragiudalf) in northeastern Ohio at rates of 0, 14.5, and 29 kg P ha−1, and to a Loudon silt loam (fine, illitic, mesic Aquic Hapludalf) in southwestern Ohio at rates of 0, 19, 39, 58, and 116 kg P ha−1. Soil test P levels were generally below sufficiency for maximum corn production at both sites. Over a 3‐yr period at the Wooster site, both fertilized and unfertilized plots showed significant accumulations of P near the soil surface; however, subsurface banding reduced surface accumulation at the highest P rate. At both sites, banding P generally produced higher yields than broadcasting at equivalent rates. When yields, soil test P levels and fertilizer rates were fit to the Bray‐Mitscherlich function, the resulting equations indicated greater fertilizer efficiency for band application. Comparison of equations derived from data in the present study with the equation used for making P fertilizer recommendations for conventional tillage in Ohio indicated the need for higher broadcast fertilizer rates in no‐tillage and also a higher soil test P level for P sufficiency in no‐tillage when compared with conventional. The advantages of banding and lower broadcast fertilizer use efficiency in no tillage seen in this study are contrary to conclusions drawn from previous studies dealing with no‐tillage fertilization.
Extraction of Apoplastic Water during Pressure‐Volume Dehydrations1
Authors: Cortes P. M. , Sinclair T. R.
Published: July 2010

In interpreting pressure‐volume (P‐V) curves, it would be helpful to know the effects of relaxing some of the assumptions generally made in their analysis. More specifically, the consequences of apoplastic water loss during dehydration are of interest. The fraction of water acting osmotically was determined from pressure‐volume curves generated for water and drought‐stressed leaves from field‐grown soybean plants [Glycine max(L.) Merr. ‘Wilkin’]. All plants showed a seasonal increase in the apparent fraction of water acting osmotically. Occasionally, particularly in the stressed leaves, the osmotic fraction was higher than previously reported and in some cases > 1. During the generation of P‐V curves, the volume of apoplastic water is generally assumed to remain constant as plant tissue dehydrates. A recent analysis of water release curves allowed the volume of apoplastic water to vary during dehydration, but the form of the resulting equation relating water potential to relative water content did not apply directly to P‐V curves. This equation was transformed into the form generally used to interpret the curves. In this form the equation suggests that the anomalously high observed osmotic fractions may be due to the loss of apoplastic water during dehydration.
Seed Yield of Austrian Winter Field Peas Intercropped with Winter Cereals1
Authors: Murray G. A. , Swensen J. B.
Published: July 2010

Intercropping has improved the production of annual food grasses and legumes in several warm‐season areas of the world. Winter cereals intercropped with winter peas may improve winter pea yields in many cool‐season areas. The primary objective of this study was to compare seed yield of winter peas in mono‐ and intercropped culture in northern Idaho. Winter peas (Pisum sativumspp. arvenseL. Poir) were intercropped with either winter wheat (Triticum aestivumL.) or winter barley (Hordeum vulgareL.) on a Tilma silt loam (fine, mixed, mesic Xeric Argialboll) in 1980–1981 and on a Palouse silt loam (fine‐silty, mixed, mesic Pachic Ultic Haploxeroll) in 1981–1982. Winter peas and winter cereals were planted either alone or in mixtures containing 25, 50, or 75% winter peas. Seeding rates of 67 and 90 kg ha−1were used for both monocrops and intercrops. All trials were conducted in fields that had been fallowed for 1 yr prior to planting the intercropping studies. Winter peas in mixtures with 25% winter cereals produced seed yields equal to or 27% greater than (P< 0.05) monocropped winter peas. Winter cereal yields were reduced an average of 60% (P< 0.05) when mixed with 25% winter peas (20 winter pea plants m−2). Monocropped winter wheat and winter barley produced higher seed yields than intercrops and monocrop winter peas under adequate N conditions, but winter peas produced higher seed yields than intercrops or monocrop winter cereals when N was partially limiting in the spring due to water logging. Seeding rate had no influence on seed yield but did increase plant populations of each species. Winter peas were compatible with winter cereals in both planting and grain harvesting requirements and pea seed can be easily separated from harvested mixtures.
Forage and Nitrogen Contributions of Arrowleaf and Subterranean Clovers Overseeded on Bermudagrass and Bahiagrass1
Authors: Evers G. W.
Published: July 2010

Tropical perennial grasses are the foundation of the pasture systems in the southeastern USA. However, they are low quality and require N fertilizer. Forage production and distribution and N accumulation of clover‐grass mixtures were compared to that of the grass alone receiving various rates of N fertilizer on a Crowley soil (fine, mortmorillonitic, thermic Typic Albaqualf). ‘Coastal’ bermudagrass [Cynodon dactylon(L.) Pers.] and ‘Pensacola’ bahiagrass (Paspalum notutumFlugge) sods were (i) overseeded with ‘Yuchi’ arrowleaf (Trifolium vesiculosumSavi) or ‘Mt. Barker’ subterranean clovers (Trifolium subterraneumL.), (ii) fertilized with 0, 84, 168, 252, or 336 kg N ha−1, or (iii) overseeded with arrowleaf or subterranean clover plus 112 kg N ha−1. Dry matter production of clover‐Coastal bermudagrass and clover‐bahiagrass mixtures was not significantly different from the grass alone at the 168 and the 252 kg N ha−1rate, respectively. Overseeding clovers improved seasonal forage distribution by providing forage one to two months earlier and reduced the May–June forage peak exhibited by the N fertilizer‐grass treatment. Average annual N accumulations of clover‐grass mixtures ranged from 177 to 217 kg N ha−1, which equaled or exceeded the 336 kg N rate except for the arrowleaf–bermudagrass mixture. The amount of N fertilizer required by the grass to replace the clover dry matter contribution was 127, 211, 160, and 254 kg N ha−1for the arrowleaf‐bermudagrass, arrowleaf‐bahiagrass, subterranean‐bermudagrass, and subterranean‐bahiagrass mixtures, respectively. Applying 112 kg N ha−1to clover‐grass mixtures did not improve total yield, forage distribution, or N accumulation, but did decrease percentage clover in the stand 5 to 33%.
Salinity Tolerance of Winged Bean as Compared to that of Soybean1
Authors: Weil Ray R. , Khalil N. A.
Published: July 2010

Winged bean [Psophocarpus tetragonolobus(L.) DC] has been called an underutilized crop with the potential to become a major protein crop for the tropics and subtropics. As with soybean [Glycine max(L.) Merr.] the introduction of winged bean to warm arid regions will be affected by tolerance to salinity. In this study a prolific Sri Lankan winged bean accession (‘SLS47’) and two soybean cultivars (‘Jackson’ and ‘Lee’) were grown in pots of sandy soil amended with NaCL to give saturated paste electrical conductivities (EC) of 0.5, 2.5, 4.5, 6.5 and 8.5 dS m−1. At 0.5 dS m−1, dry matter accumulation (0.84 g plant−1), nodule mass, (32 mg plant−1), and tissue N (24 mg Ng−1) of winged bean were similar to those of both soybean cultivars. At 65 d after planting, however, specific nitrogenase activity by acetylene reduction assay was much lower for the winged bean (60 μmol ethylene g−1h−1) than for the soybean (160 to 190 μmol ethylene g−1h−1). The results indicated that winged bean was at least as tolerant as Lee soybean and more tolerant than Jackson. Though stunted, at 8.5 dS m−1winged bean showed significantly less foliar injury than did either of the soybean cultivars. For the soybean, the tissue N content was unchanged, but for winged bean it increased significantly with increasing salinity, suggesting that dry matter accumulation,especially by winged bean, was more sensitive to salinity than to N2fixation.
Wheat and Forage Sorghum Response to Residual Phosphorus in Blackland Soils1
Authors: Hipp Billy W.
Published: July 2010

Phosphorus fertilizers are generally applied for crops grown on Blackland Prairie soils of Texas, but the crop yield response due to residual P from single applications of P is unknown. Studies were conducted over a 5‐yr period (1977 to 1981) on Austin silty clay (fine‐silty, carbonatic, thermic Entic Haplustolls) and Dalco clay (fine, montmorillonitic, thermic Udic Pellusterts) soils to evaluate the residual effects of P on subsequent crops. Fertilizer rates of 0, 25, and 50 kg P ha−1were applied in 1977,1978, and 1979 at three sites with soil P levels of 6,10, and 13 mg kg−1NaHCO3‐extractable P (0 to 15 cm depth). Following the initial crop year, plots were split to include 25 kg P ha−1with the seed. The other half received no fertilizer P other than the initial P application. The test crops were wheat (Triticum aestivumL.), forage sorghum (Sorghum bicolorL. Moench), and sweet clover (Melilotus albusLam.). A significant yield increase due to initial P application was obtained at each site. Crop yield increases due to residual effects of the 50 kg P ha−1rate ranged from 0 to 20%, while yield increases due to 25 kg P ha−1at planting ranged from 19 to 43%. Percent yield increase from residual P was greater on soil with 6 mg kg−1soluble P than on soil with 13 mg kg−1soluble P. Phosphorus concentrations in wheat plants were increased by residual P, but were much higher in plants receiving P at planting. These data indicate that some yield increase can be expected from residual P from a single application of moderate amounts of P. For more efficient use of P and high yields, P should be applied to each crop if initial NaHCO3‐extractable P levels are between 6 and 13 mg kg−1.
Field Measurements of Ammonia Loss from Surface Applications of Urea Solution to Bare Soil1
Authors: McInnes K. J. , Ferguson R. B. , Kissel D. E. , Kanemasu E. T.
Published: July 2010

Factors influencing ammonia (NH3) volatilization from surface‐applied urea have been studied extensively; however, almost all research has been done in a manner that modifies the environment compared to field conditions. Results from such studies, therefore, may incorrectly assess actual losses in the field. Our objective was to evaluate the magnitude of NH3volatilization and how soil temperature, soil water, and other environmental factors affected rates of loss. Three studies were conducted to assess the volatilization of NH3from surface‐applied urea, two on a silt loam and one on a very fine sandy loam soil. A mass‐balance micrometeorological method, which produces very minimal disturbance of the natural environment was used in all studies. Diurnal patterns of NH3loss, which coincided with the fluctuations in surface temperature and water content, were found in each study. In all studies, loss followed most closely the pattern of urea hydrolysis. Urea hydrolysis in the surface soil was slowed by dry conditions and approached zero when the soil was near “air dryness.” Rainfall of 0.86 cm did not prevent further NH3loss from Muir silt loam soil (fine‐silty, mixed, mesic Pachic Haplustolls). Three simulated rainfalls with 0.5 cm of irrigation separated by 3 and 4 days did not curtail loss from Haynie very fine sandy loam soil (coarse‐silty, mixed, mesic Typic Udifluvents), but rather enhanced the rate of volatilization, probably due in part to an increased rate of urea hydrolysis.
Timing of Weed Control in No‐Tillage Wheat Crops
Authors: Forcella F.
Published: July 2010

Timing of successful weed control in no‐tillage wheat is not well known, yet weeds, especially annual grasses, may reduce yields considerably in such crops. To evaluate the effect of weed control on no‐tillage wheat production, a 2‐yr study of the timing of wheat/weed interference was initiated in southeastern Australia, a region that effectively has a winter‐wet/summer‐dry climate. In this study, weeds were controlled either manually or chemically at various stages of crop growth. Wheat yield or dry weights were determined at harvest. Additionally, soil temperature, soil water, and available soil N were monitored throughout the growing seasons. If autumnal rains commenced early and the crop was sown early (i.e., before May), then significant wheat/weed competition took place only in May. However, if the crop was sown late (i.e., after May), then wheat/weed competition occurred only in early September. In all cases, wheat/weed competition increased when soil temperature exceeded 10°C and resulted in rapid depletions of available soil N.
The Use of Nitrogen‐15‐Depleted Ammonium Sulfate for Estimating Nitrogen Fixation by Leguminous Trees1
Authors: van Kessel Christopher , Nakao Patty
Published: July 2010

The feasibility of using 15N‐depleted (NH4)2SO4for assessing biological N2fixation of leguminous trees was investigated. A slowgrowing species, lebbeck [Albizia lebbeck(L.) Benth], and a fastgrowing species, leucaena [Leucaena leucocephala(Lam.) de Wit] were inoculated with appropriate Rhizobiumstrains and grown under four different levels of N. Each week, 0, 5, 12.5, or 25 mg of 15N depleted (NH4)2SO4was applied to the upper chamber of the Leonard assembly. After 10 and 18 weeks growth for leucaena and lebbeck respectively, plants were separated into shoots, roots, and nodules for analysis. The atom% 15N in shoots and roots was linearly correlated to the amount of applied 15N‐depleted (NH4)2SO4. Significant differences in atom% 15N and percentage N derived from N2fixation were measured in lebbeck and leucaena when, respectively, more than 8.3 and 2.9% of the total N was derived from (NH4)2SO4. Nodules derived a larger portion of their total N from N2fixation than did the roots or shoots, indicating that most of the N present in the nodules was derived from N2fixation. Nodules of both species at the no N treatment showed slightly higher atom% 15N values than the 15N‐natural abundance level of atmospheric N2.
Combinations of Preplant‐Banded and Seed‐Banded Applications of Nitrogen and Phosphorus Fertilizer for Winter Wheat Production1
Authors: Cabrera M. L. , Kissel D. E. , Whitney D. A.
Published: July 2010

The application of N and P fertilizers together in deep, preplant bands is an effective method of fertilizer placement for winter wheat (Triticum aestivum L.). However, it produces uneven growth of wheat with the greatest growth directly over the preplant bands. Two field studies were conducted on a Crete series soil (fine, montmorillonitic, mesic Pachic Argiustoll) to determine if the addition of N and P fertilizer banded with the seed could eliminate this uneven growth and, in turn, increase grain yields. Wheat was planted in rows perpendicular to the preplant bands so that plant and spike samples could be taken from row sections located at different distances from the preplant band. In 1980‐1981, seed‐banded fertilizer increased tillering and early dry‐matter production in all row sections. However, these increases did not translate into higher spike densities or grain yields. In 1981‐1982, seed‐banded fertilizer increased tillering and early dry‐matter production in row sections between preplant bands, which reduced but did not eliminate the uneven growth caused by preplant bands. Although significant grain yield increases were obtained in row sections between preplant bands, no significant increases in overall grain yield were found. Results indicate that the addition of seed‐banded fertilizer can increase overall early dry‐matter production and may reduce, although not eliminate, the uneven growth caused by preplant bands.
Use of a Hydraulic Press for Estimation of Leaf Water Potential in Grain Sorghum1
Authors: Hicks S. K. , Lascano R. J. , Wendt C. W. , Onken A. B.
Published: July 2010

The hydraulic press (HP) is a highly portable instrument designed for rapid measurement of leaf water potential of plants. This study compared grain sorghum [Sorghum bicolor (L.) Moench] leaf water potentials measured with a pressure chamber (PC) and using two endpoints with a HP, under glasshouse conditions. The first endpoint is when water exudes from one vein and the second endpoint when water exudes from all veins on both sides of the leaf tissue. The results showed that the HP and PC measurements agreed well in the range of −0.5 to −3.5 MPa of leaf water potentials when the second endpoint was selected for the HP. The HP can be used to measure the leaf water potential of grain sorghum, provided it is calibrated using the second endpoint against a PC or another method.