bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Tillage on Fertilizer Requirements for Corn on a Silt Loam Soil1
Authors: Ketcheson J. W.
Published: July 2010

Corn (Zea mays L.) yields less with no‐till or reduced tillage than with conventional tillage on medium and fine‐textured soils in Ontario, Canada. This study was undertaken to determine whether rates of N, P, or K above those normally recommended could increase the no‐till yields. Annual rates of 120 and 240 kg N/ha, and initial rates of 95, 475, and 1,260 kg P/ha and 95, 665, and 1,330 kg K/ha were applied to a silt loam soil (Albaquic Hapludalf) in combination with four different tillage treatments (fall moldboard plow, spring disc; fall mulch plow with heavy duty cultivator, spring disc; fall ridge; no‐till). Corn was grown, harvested for grain, and stover returned to the soil over a 6‐year period. Increasing N, P or K applications gave similar response patterns on each tillage treatment. There was no indication that the higher nutrient applications could overcome yield depressions associated with reduced tillage. Adequate N, P, K levels in corn tissue further substantiated an adequate nutrient supply with each tillage treatment. Resistance to penetration measurements on soil suggested that mechanical impedance might be more critical than nutrient supply in growth performance and explain the lower yields with reduced tillage. Soil tests for available P and K, combined for increments of the upper 30 cm of soil, tended to be higher with no‐till than with the plow treatment.
Toxaphene Volatilization from a Mature Cotton Canopy1
Authors: Willis G. H. , McDowell L. L. , Smith S. , Southwick L. M. , Lemon E. R.
Published: July 2010

abstract

To fully understand the pollution potential of pesticides more knowledge concerning the mechanisms and rates of pesticide exchange between environmental compartments is needed. The momentum balance method was used in a field study to characterize toxaphene (chlorinated camphene) volatilization from cotton (Gossypium hirsutum L.) plants for 5 days following aerial application at 2.24 kg/ha. The momentum balance method uses accurate measurements of windspeed profiles, temperature gradients, and atmospheric pesticide concentration gradients above the plant canopy to provide data for calculating vertical flux densities of pesticides. The calculated volatile loss for the 5‐day period was 358 g/ha, which represented a loss of 26% of the toxaphene present in the canopy. Although typical volatile loss patterns suggested that flux densities were highest during midafternoon, there was evidence that volatility rates were also high when leaves were drying after heavy dew or light rain. Based on comparisons of the amounts of toxaphene transported from nearby cotton fields via surface runoff in earlier studies and the amounts lost by volatilization in this study, it was concluded that aerial transport is the pathway of greater loss.
Cornstalk Decomposition on a Till‐Planted Watershed1
Authors: Alberts E. E. , Shrader W. D.
Published: July 2010

Cornstalk (Zea mays L.) residue can be used for many competing purposes including energy production and erosion control. This study was conducted to determine the rate of cornstalk decomposition and N and P release on a till‐planted watershed in the Corn Belt. Samples of cornstalk residue were periodically collected from 12 sites distributed over the watershed and analyzed for weight loss and plant nutrient content. After 12 months, 79% of the residue had decomposed. About two‐thirds of the decomposition occurred from November to April when soil temperatures were unfavorable for high microbial activity. Nitrogen and P were released from the residue during the early stages of decomposition. After 12 months, 60% of the N and 74% of the P had been lost. The percentages of N and P in the residue rapidly increased during the last 3 months of the study when soil moisture and soil temperature were favorable for optimum activity. The C/N ratio declined from 48 to 23. Narrowing of the ratio was caused by a proportionately greater decrease in C content than in N content.
Effect of Nitrapyrin and N Fertilizer on Yield and Mineral Composition of Corn1
Authors: Warren H. L. , Huber D. M. , Tsai C. Y. , Nelson D. W.
Published: July 2010

Fertilizer N applied in the fall or early spring is often used less efficiently than N applied closer to the time of maximum N demand by plants. Nitrification inhibitors make it possible to delay nitrification of applied NH4+‐N in the soil and thereby reduce overwinter and early spring N loss from leaching and denitrification. Because NH4+ absorption may induce changes in plant mineral composition, we evaluated under field conditions, the effect of inhibiting nitrification of NH4+‐N on the mineral composition of corn leaf tissue as well as on grain yield and protein content. Anhydrous ammonia with and without nitrapyrin [ 2‐chloro‐6‐(trichloromethyl) pyridine] at 0.55 kg/ha was applied in the fall and spring on soils of three types. Addition of nitrapyrin to fall‐applied NH4+ significantly increased grain yield and grain protein. Grain protein was sometimes increased when nitrapyrin was applied with NH4+ in the spring. Grain protein content was increased by N and nitrapyrin and from 10 to 33%. Protein generally continued to increase even after the maximum yield had been reached. The mineral composition of leaves was more dependent on soil type than on N treatment. The minerals K, Ba, and Mn were higher, and Ca, Mg, and A1 were lower in plants grown in Tracy sandy loam (Ultic Hapludalfs, coarse‐loamy, mixed, mesic) than in those grown in either Runnymede loam (Typic Argiaquolls, fine‐loamy, mixed, mesic) or Chalmers silty clay loam (Typic Haplaquolls, fine‐silty, mixed, mesic) soils. The concentrations of minerals in plants were similar with fertilizer treatments and time of application. Zinc was the only mineral in plants that significantly increased when nitrapyrin was added to NH4+. Nitrification inhibitors can effectively reduce N losses without adversely affecting the uptake of other minerals or the mineral composition of corn leaf tissue.
Yield, Legume Introduction, and Persistence in Permanent Pastures1
Authors: Baker Barton S.
Published: July 2010

Permanent pasture in hill land is frequently on steep and/or rough land unsuited to frequent travel with ground equipment. Ways are needed to introduce and maintain legumes on such land. This study involved 18 treatments using P (208 kg/ha), Mo (2.2 kg/ha), lime (6.5 metric ton/ha), rototilling and white clover, Trifolium repens L. seed (2.2 kg/ha) in various combinations on two permanent pastures in central West Virginia to investigate ways of increasing yields and introducing legumes, and to determine persistence of introduced legumes. A limestone soil (Typic Hapludalf) produced higher yields when treated than a sandstone soil (Typic Dystrochrept) but the reverse was true when no treatments were applied. Legume introduction was more successful on limestone soil than sandstone soil. Phosphorus application was the most critical aspect of treatment on the limestone soil relative to legume introduction and yield increase, whereas liming was the most critical aspect of treatment on the sandstone soil.

Legumes on the limestone soil accounted for over 75% of the total forage produced on some plots the year following treatment. Total legume content decreased after the 2nd year and reached a low of near 10% during the 4th year. Volunteer legumes, mostly white clover and red clover (Trifolium pratense L.), accounted for as high a percentage of the total yield as the seeded legume during the 4th and 5th years. On the sandstone soil none of the treatments resulted in enough legumes to account for more than 20% of the forage. Introduction of legumes increased yield and skewed the seasonal distribution pattern toward a higher percentage of total yields early in the season. Molybdenum did not influence legume introduction, yield, or persistence.
Response of Tropical Grasses to Stocking Rate1
Authors: Adjei M. B. , Mislevy P. , Ward C. Y.
Published: July 2010

During favorable growing conditions tropical stargrasses (Cynodon spp.) are highly productive, producing more forage than is utilized by cattle under normal stocking rates, and resulting in large amounts of low quality, standing residue. Therefore, grazing trials were conducted to study the effects of three stocking rates (SR) (7.5, low; 10, medium; and 15 cattle/ha, high) on forage yield, quality, utilization and animal performance of three stargrasses: ‘UF‐5’ and ‘McCaleb’ (Cynodon aethiopicus Clayton and Harlan) and ‘UF‐4’ (Cynodon nlemfuensis Vanderyst var. nlemfuensis). Additionally, the medium SR was imposed on “Transvala” digitgrass (Digitmia decumbens Stent.) and “Pensacola” bahiagrass (Paspalum notatum Flugge). The average annual dry matter (DM) yields of stargrasses at low, medium, and high SR and of digitgrass and bahiagass at medium SR were 17.0, 18.3, 20.1, 15.0, and 10.0 metric tons/ha, respectively. In 1976, the in vito organic matter digestibility of digitgrass (51%) and UF‐5 (49%) was superior to that of UF‐4 and McCaleb (46%) stargrass with bahiagrass averaging 46% and 50% in 1976 and 1977, respectively. Crude protein in all entries was similar, averaging 9.9%. Seasonal DM utilization (75 to 95%) of stargrass by cattle was directly related to SR. However, forage intake of 7.6 kg DM/animal/day at the high SR was lower than at the medium (9.3) and low SR (10.2). Forage DM consumed annually (168‐day period) at the medium SR averaged 16.7 metric tons/ha For stargrasses, 14.9 for digitgrass and 9.9 for bahiagrass. Cattle average daily gain (ADG) over seasons ranged from 0.18 to 0.56 kg/dayfor stargrasses, and was an inverse linear function of SR. The ADG measured at a 6‐week interval was a curvilinear function of grazing pressure (GP) with an optimum GP of 6 to 8 kg available forage DM/100 kg body weight/day at 7.5 cm height of cut. Seasonal (168 days) beef gains (2‐year average) on stargrasses were 470, 617, and 576 kg/ha at the high, medium, and low SR, respectively. The ADG and beef product/ha at the medium SR in 1976 on stargrass, digitgrass, and bahiagrass averaged 0.35, 0.28, 0.22, kg/day, 580, 461, and 396 kg/ha, respectively. These data indicated that although ADG is low, high yields of total beef/ha can be obtained with proper stocking rates and correct grazing pressure on stargrass pastures.
Magnesium in Grasses of Three Selected Regions in the United States and its Relation to Grass Tetany1
Authors: Kubota Joe , Oberly G. H. , Naphan E. A.
Published: July 2010

Grass tetany, a conditioned Mg deficiency, is a serious nutritional disease in cattle in various parts of the United States. While year to year variability is high, disease incidence is notably higher in some areas than others, indicating that soils, species of grasses, and temperature may be contributing factors. The Mg concentrations in grasses were determined to identify regional patterns and factors that affect them. Attention was focused on three distinctly different regions: 1) western U.S. from southern Nevada to Oregon, 2) eastern U.S. from North Carolina to Maine, and 3) central U.S. including the Lake states. In the West, the Mg concentration was low in grasses grown on droughty soils formed in volcanic ash. In the eastern U.S., the Mg concentration in grasses decreased from North Carolina to Maine, indicating the dominance of temperature over soils. In the North Central Region, the dominance of dolomitic till (Wisconsin) over calcitic till (Michigan) as sources of soil parent material was evident in the production of Mg adequate grasses for livestock. Regional patterns of tetany incidence seemed more closely associated with grasses having less than 0.2% Mg than with grasses having K/(Ca+Mg) ratios of 2.2 or more.
Regrowth and Alcohol Dehydrogenase Activity in Waterlogged Alfalfa and Birdsfoot Trefoil1
Authors: Barta A. L.
Published: July 2010

Susceptability of alfalfa (Medicago sativa L.) to waterlogging injury seriously limits its persistance and adaptability. Waterlogging injury and accumulation of ethanol under root anoxia may be causal agents which facilitate or promote infection by Phytophthora megasperma Drechsler zoospores and result in “root rot” of alfalfa.

While induction of alcohol dehydrogenase (ADH) and increased root accumulation of ethanol are general characteristics of flood‐intolerant species, these parameters have not been examined in alfalfa and birdsfoot trefoil (Lotus corniculatus L.) which vary greatly in flood tolerance and Phytophthora resistance. The objective of this greenhouse study was to compare the flooding response of alfalfa and birdsfoot trefoil and determine the effect of anoxia on the induction of ADH and accumulation of ethanol in flooded roots of both species.

When flooded for 7 days, alfalfa exhibited much more severe shoot injury symptoms (wilted and yellowing leaves), reduced shoot dry weight, reduced shoot and root total nonstructural carbohydrates, and reduced rates of acetylene reduction than trefoil which is Phytophthora resistant. Induction of ADH activity was very rapid and reached similar levels in both alfalfa and trefoil. Flooding for 6 days at 22 C resulted in maximum ethanol concentration in alfalfa after which shoot injury symptoms rapidly developed. However, ethanol concentration in trefoil roots was several fold lower than alfalfa indicating that trefoil may effectively remove ethanol from the roots.
Nitrogen Loss in Conjunction with Transpiration from Rice Leaves as Influenced by Growth Stage, Leaf Position, and N Supply1
Authors: da da Silva P. R. F. , Stutte C. A.
Published: July 2010

An understanding of the fate of the N used or discharged by crop plants is important to cost‐efficient producton. Recent reports from our laboratory show that leaves of several crop and weed species lose volatile N in conjunction with transpirational water vapors. This study has investigated the effects of growth stages, leaf position, transpiration rate, and N supply in relation to rate of this loss on rice (Oryza sativa L.).

A pyro‐chemiluminescent method was used to quantify the volatile N loss along with the transpirational water vapors from rice leaves. Calculations, based on collected data, estimate N loss of 14.1 (‘Bonnet 73’) to 15.2 (‘Starbonnet’) kg/ha from plant leaves over a l00day period. Rate of N loss decreased during the period between tillering and 1 to 3 weeks beyond panicle initiation after which it increased as plants progressed to the heading stage. The most recently matured leaf lost N at a higher rate than older leaves. The N concentration in nutrient solution did not affect rate of volatile N loss per unit of leaf area of the most recently matured leaf; however, older leaves supplied with high rates of N lost N at a higher rate than those grown in low‐N medium. Volatile N lost per plant increased with N supply mainly due to higher leaf area and higher N loss rate from older leaves. Quantifying the physiological influences on volatile N loss can help to determine the time for application and the amounts of N fertilizers needed for optimum rice production. Additional
Transpiration Efficiency of Potato1
Authors: Tanner C. B.
Published: July 2010

Wittwer (1979) recently has stressed the need for information on the number of kilograms of water needed to produce a kilogram of food. The objective of this study was to provide this information for potato, and in particular, to test the general proposal of Bierhuizen and Slatyer (1965) that transpiration efficiency (yield/transpiration) could be described by Y/T = k(e*−e), where k is a physico/physiologically‐based constant and (e*−e) is the average daytime saturation deficit. Regression analysis of 3 years of field data, including periodic yield measurements and daily measurements of transpiration and saturation deficits, shows that during tuber bulking, k = 0.065 ± 0.007 mb for both tubers and total dry matter. This experimental k is in good agreement with a k derived from physiological data for potato. During early vine growth we found k = 0.055 ± 0.006 mb. These k values disagree with data of Rijtema and Endrodi (1970) which yield k = 0.015 mb. Sources of variability in k and the difference between the Wisconsin and Rijtema and Endrodi data are discussed.

It is clear that since evapotranspiration is greater than transpiration, ET‐efficiency is less than T‐efficiency; therefore k ≈ 0.065 mb sets an upper limit of potato water‐use efficiency for a given saturation deficit regime. Also potato water‐use efficiency will be higher in humid regions than in semi‐arid regions because of lower saturation deficits, particularly where advection exists.
Hay Yield Determinations of Mixed Swards Using a Disk Meter1
Authors: Baker Barton S. , Eynden Thomas Vanden , Boggess Neal
Published: July 2010

Estimates of hay yields are frequently desirable for purposes of measuring fertilizer response, studying effects of management and cultural practices, and determining animal units that can be maintained on forage produced from a given area. Estimates of forage yield can be obtained by cutting and weighing, but the random collection of forage samples for estimating yields is not a viable alternative in some cases. A convenient, quick, and accurate method of determining forage yields in situ would benefit research workers and those involved in commercial and extension agriculture operations.

The purpose of this investigation was to determine the suitability of using a disk meter to estimate dry matter yield of mixed swards. A 0.5m2 disk meter was constructed from hardboard paneling, steel pipe, and a flange. Paired disk meter readings and dry matter yields from clipping were taken from 708 swards used for hay production in 1978. Swards consisting of cool season grasses, legumes, and weeds were characterized into 14 categories according to species composition and growth stage. Regression equations were determined for each category from paired disk readings and dry matter yields from clippings. The slopes of the regression lines for the different categories were not significantly different. The coefficient of determination (r2) was 0.82 when using a single regression line for all categories. The points of intercept of the regression lines on the vertical axis for the different categories were different with a definite trend for regression lines for first cutting swards to intercept higher than regression lines for aftermath.

The formula which best described the relationship between disk reading and yield was: yield estimate = intercept for category + 183 (disk reading) − 1.73 (disk reading)2. In order to test the disk meter and formula method, yields on 40 swards were determined independently using two methods. The correlation coefficient between sward yields estimated using the disk meter and formula and sward yields estimated using weighed clippings was +92.
Sunflower Cultivar Performance as Influenced by Soil Water and Plant Population1
Authors: Prunty Lyle
Published: July 2010

Information on the yield performance of sunflower (Helianthus annuus L.) as related to a range of soil water potential in the near‐optimum range has not previously been reported. Previous studies of sunflower plant population density effects on yield have lacked agreement. In this study three sunflower cultivars (‘Peredovic’, ‘894’, and ‘Northrup King 212’) were tested for response to soil water potential at Oakes, North Dakota and for response to population density at Carrington, North Dakota (irrigated) and Fargo, North Dakota (dryland). Yield was higher if the soil water potential in the root zone, as measured by commercial tensiometers, was limited to values of ‐20 cbar and ‐40 cbar and was lowered if the root zone water potential was allowed to drop to ‐75 cbar. There was no significant difference in seed yield between populations at thinning of 49,400, 59,300, and 69,200 plants/ha. A comparison of harvest methods at Oakes indicated that a number‐of‐heads harvest method increased yield estimates by 20% compared to an area harvest method. This comparison also showed that the harvest method used did make a significant difference in yield results obtained from the water potential experiment. It is hypothesized that harvest method may have influenced previous sunflower population density experiments similarly.
Growth and Photosynthate Partitioning in Alfalfa Under Eight Temperature‐Photosynthetic Period Combinations1
Authors: Chatterton N. J. , Carlson G. E.
Published: July 2010

A characterization of the growth responses of high and low yielding alfalfa (Medicago sativa L.) plants to environmental parameters will provide important information on their yield potential. This experiment was conducted to determine if growth temperature and length of the photosynthetic period mediate the differential herbage yielding abilities of alfalfa genotypes previously selected under field conditions for high and low herbage yield. Twelve genotypes were grown at 20/15, 23/18, 26/21, and 29/24 C day/night temperatures in 10‐hour and 14‐hour photosynthetic periods in controlled environments. Dry weights and total nonstructural carbohydrate percentages were obtained on herbage and root tissues. Carbon dioxide exchange rates were measured using infrared gas analysis on attached leaves and expressed on a per unit leaf area and a per unit leaf dry weight basis. Relatively large herbage yield differences previously observed among the various clones under field conditions were minimized in all treatments when plants were grown in controlled environments where moisture and nutrient stresses were assumed to be minimal. The apparent diurnal accumulation rate of total nonstructural carbohydrates was faster in the herbage of plants grown in short photosynthetic period conditions than in those grown in long ones. Such a relationship suggests an influence on photosynthate partitioning by length of the daily photosynthetic period. We conclude that yield differences observed under field conditions were not necessarily related to differential responses to either temperature or length of the daily photosynthetic period. Furthermore, photosynthesis, as measured by single leaf CO2 exchange rate, was not positively correlated with herbage yield under the various controlled environmental conditions used in this experiment.
Effect of Rhizobium japonicum Inoculant Rates on Soybean Nodulation in a Tropical Soil1
Authors: Smith R. S. , Ellis M. A. , Smith R. E.
Published: July 2010

Soybean [Glycine max (L.) Merr.] research and production is expanding in tropical areas. Successful soybean nodulation in a soil free of Rhizobium japonicum is dependent totally upon viable rhizobia from the inoculant. This study examined soybean nodulation as influenced by the rate of applied R. japonicum in a tropical soil without indigenous R. japonicum.

Rates of R. japonicum were evaluated with soybeans grown in a field experiment on a Puerto Rican Coto clay (Typic Haplorthox, clayey, kaolinitic, isohyperthermic) lacking indigenous R. japonicum. Eight rates of liquid inoculation were added to the seed furrow at planting and supplied number of R. japonicum from log 2.59 cells/cm row with 10 fold increases through log 9.59 cells/cm row. R. japonicum rates of log 2.59 and 3.59 cells/cm row were not successful in establishing nodulation. Nodule numbers increased with increasing rates of applied rhizobia from log 4.59 up to the highest rate of log 9.59 viable cells/cm. Regression analyses indicated linear relationships between the rate of inoculation with rhizobia and the number of tap root nodules, total number of nodules, and nodule weight/plant. An inverse relationship was observed between weight/nodule and total number of nodules. Inoculation levels above log 5.0 rhizobia/cm were necessary to establish effective nodulation in a R. japonicum free tropical soil.
Fruiting of Upland and Pima Cotton with Different Planting Dates1
Authors: Kittock D. L. , Henneberry T. J. , Bariola L. A.
Published: July 2010

Interest in short‐season cotton production is increasing because of late‐season insect problems and, in the West, because of the expense of irrigation. Diverse cultivars of Upland cotton (Gossypium hirsutum L.) and American Pima cotton (G. barbadense L.) were compared at Phoenix, Arizona to evaluate short‐season production using several planting dates in 3 years and three dates of final irrigation in one of the years. The soil was a fine‐loamy, mixed (calcareous), hyperthermic, Anthropic Torrifluvents. Lint yield of Upland cotton was not reduced when planted as late as 7 May, except when irrigation was terminated in mid‐August. In contrast, lint yields of Pima cottons were reduced with each later planting date, except for the earliest planting and latest irrigation and harvest. Plant populations in 2 years had no interaction with planting dates for lint yield. The dates of seedling emergence and dates of early flowering occurred about the same time for Upland and Pima cotton in most plantings and therefore could not account for the differences between species in yield response to dates of planting and final irrigation. The rate of flowering, once started, was much slower for Pima cotton than Upland cotton. ‘Pima S‐5’ reached peak flowering an average of 18 days later than ‘Deltapine 61’ (DPL 61). Weekly lint production far DPL 61 was 4.5 times that for Pima S‐5 in August, twice that of Pima S‐5 in September, but only three‐fifths that of Pima S‐5 in October. Pima strain ‘79–106’ was intermediate between DPL 61 and Pima S‐5 in earliness of lint production. We conclude that Pima cotton requires early planting and nearly full‐season production for highest yield. Early planting is not as critical for Upland cotton, unless early crop termination is planned.
The Interrelationship Among Nutrient Elements Applied to Calcareous Sand Greens1
Authors: Christians N. E. , Martin D. P. , Karnok K. J.
Published: July 2010

A field study designed to observe the interacting effects of applied N, P, and K on the growth and quality of creeping bentgrass (Agrostis palustris Huds. ‘Penncross’) was conducted on highly calcareous, experimental, sand greens at Ohio State Univ. in 1977 and 1978. Application rates of N and K ranged from 0 to 10.8 kg/are/year (1 are = 100 m2, 1 kg/are is approximately 2 lbs./1,000 ft2) and application rates of P ranged from 0 to 5.4 kg/are/year. Data were also collected on the effects of applied nutrients on a number of soil test measurements. Potassium test levels ranged from 52 to 252 kg/ha after the 2nd year of the study. Increasing rates of N and K interacted in their effect on K soil test levels. Potassium test level in plots receiving 10.8 kg/K/are/year were 125 kg/ha higher in plots receiving no N than in plots receiving the highest level of applied N. Nitrogen and K were also observed to interact in their effects on tissue growth. At lower levels of applied N, tissue production increased with increasing levels of applied K. At high levels of applied N, tissue growth decreased slightly with increasing levels of K. Evidence is presented which would indicate that Mn may have been limiting to growth at high rates of N and K. Highest tissue chlorophyll content and quality were observed at N application rates of approximately 6 kg N/are/year. This is nearly double the rate normally recommended for greens in temperate regions.
Thatch and Quality of Meyer Zoysia in Relation to Management1
Authors: Dunn J. H. , Sheffer K. M. , Halisky P. M.
Published: July 2010

Thatch control is a serious management problem in ‘Meyer’ zoysia (Zoysia japonica Steud.), one of the best adapted turfgrass varieties in the upper South. Improved cultural methods would greatly enhance the use and adaptability of Meyer zoysia in this region. The purpose of this study was to evaluate the effectiveness of annual, mechanical thatch removal, two mowing heights, and three N carriers, each applied at two rates of N, in reducing thatch accumulation and improving quality of Meyer zoysia.

Vertical slicing reduced the thatch depth by 12 to 18% each year over a period of 5 years. Mowing at 1.9 cm compared with 3.8 cm decreased thatch by 13 to 25% annually over the same period. Thatch was not significantly affected by applications of 0.98 or 2.93/kg N/100 m2 annually with IBDU, (isobutylidene diurea), UF (ureaformaldehyde), or urea.

Mowing at 1.9 cm plus mechanical thatch removal almost eliminated “winter injury” in 1976, while zoysia turf with no thatch removal and 3.8 cm mowing was 81% injured. Nematode (Helicotylenchus spp., Tylenchorynchus spp., and Xiphinema spp.) populations were sometimes large in turf showing winter injury but there was no significant correlation of nematode genus or population size with injury. Zoysia mowed at 3.8 cm recovered more slowly following thatch removal than that mowed at 1.9 cm and was infested with Kentucky bluegrass (Poa pratensis L.) which comprised 16% of the turf after 5 years.

Thatch depth was not affected by applications of 0.98 or 2.93 kg N/100 m2 IBDU, UF, or urea. Differences in quality and fall color were small in response to N carriers and rate of application. However, UF and IBDU, particularly at the higher rate of N, stimulated henbit (Lamium amplexicaule L.) in winter and early spring when zoysia was dormant.

Mowing at 1.9 cm plus annual thatch removal, irrigation, and a moderate rate of N reduces “sponginess” and can produce good quality summer zoysia turf over a period of several years, irrespective of N carrier.
Foliar Fertilizer Damage to Corn Leaves: Relation to Cuticular Penetration1
Authors: Neumann Peter M. , Ehrenreich Yael , Golab Zvia
Published: July 2010

Foliar fertilization with N, P, K, and S has been reported to sometimes produce large yield increases in important food crops. However, zero and negative effects on yields are often reported: frequently in conjunction with foliage damage from fertilizer salts. Little is known about the mechanism of burn damage induction or the comparative damaging effects of different fertilizers applied to intact leaves.

We have compared the damaging effects of solutions of several N, P, K, and S fertilizers applied to intact corn (Zea mays L.) leaves under controlled conditions. Minor differences in the chemical structure of the fertilizers had large effects on the threshold concentration above which damage was induced. For example, K2HPO4 was damaging at concentrations ≥ 0.05 M whereas KH2PO4 became damaging only at concentration ≥ 0.50 M. Penetration of these two compounds through the intact cuticle occurred at similar rates and was dependent on concentration rather than type of salt. Transfer away from the site of application was slow and significant differences in transfer rate were not observed. We conclude that all osmotically‐active fertilizer compounds can induce plasmolytic damage when sufficiently high concentrations penetrate into the leaf. However, fertilizers such as K2HPO4 and some others with a higher range of solution pH have specific toxic effects which can induce cell and tissue necrosis at relatively low concentrations.
Root Development of Winter Wheat as Related to Tillage Practice in Western Nebraska1
Authors: Wilhelm W. W. , Mielke L. N. , Fenster C. R.
Published: July 2010

Tillage practices can influence crop root development. Root distributions were determined for wheat (Triticum aestivum L.) grown in a wheat‐fallow rotation during the 1977–1978 winter wheat crop year on an Alliance silt loam (Aridic Argiustoll). The fallow tillage treatments were plow, subtillage, and chemical (no tillage). Each tillage treatment was split into subplots for N application of 0 or 45 kg/ha.

Rooting density was determined by washing the roots in soil cores 7.6 cm in diam by 15 cm long extracted to depths of 90, 105, and 120 cm on 28 Mar., 2 May, and 8 June 1978, respectively. After root length was determined, roots were dried and weighed. Soil penetration resistance was determined with depth in the soil by inserting a penetrometer horizontally 4 cm into the soil at vertical intervals of 10 cm from the surface.

Root weight was greatest for the chemical treatment (46 mg/dm3) and least for the subtillage treatment (26 mg/dm3). Approximately 62% of the total root mass was in the upper 30 cm of soil with maximum rooting depth greater than 120 cm for all treatments by 8 June 1978. Root development was limited by the alluvial horizon at a depth of about 25 to 40 cm. Visual observations also showed some root resistance by tillage shear plane at 10 cm. Nitrogen fertilization did not significantly change the rooting pattern; however, the N‐by‐tillage interaction for root weight was significant at the second sampling date—the subtillage treatment showed a positive response to added N, while chemical and plow treatments showed a negative response. Wheat yields were not significantly influenced by fallow tillage or N. This indicated that root development occurring above and below the resistant layer was sufficient to supply the plant with its water and mineral needs.
Response of Soybean Plants to High Root Temperature as Affected by Plant Cultivar and Rhizobium Strain1
Authors: Munevar F. , Wollum A. G.
Published: July 2010

This study examined the effect of high root temperatures on nodulation, dinitrogen fixation, and growth of five soybean [Glycine max (L.) Merr.] cultivars associated with either of two Rhizobium japonicum strains of contrasting temperature tolerances.

In each of three greenhouse experiments, soybeans growing in pots containing vermiculite were submitted to root temperatures of 28, 33, and 37 C or 28, 33, and 35 C by submerging the pots in thermostatically controlled water baths. In the first experiment, cvs. ‘Hutton’ and ‘Ransom’ were inoculated with either strain USDA 110 or 587, while in the second experiment the same strains were used to inoculate cvs. ‘Gasoy‐17’ and ‘Bragg.’ In a third experiment cvs. Bragg, Gasoy‐17, ‘Lee,’ and Ransom were grown in association with strain 587. Plants were harvested 34 days after germination.

The superiority in high temperature tolerance of strain 587 over USDA 110, found in earlier work with cv. Lee, was confirmed for cvs. Gasoy‐17, Hutton, and Ransom. Results with cultivar Bragg were inconsistent for the two experiments in which that genotype was included.

The results indicate that soybean genotype influences the response of the symbiotic system to high root temperatures. Gasoy‐17 and Lee appeared to be more tolerant to high root temperature than the other cultivars. That characteristic was enhanced when Gasoy‐17 was associated with the tolerant strain 587. Selection of soybean cultivars with tolerance to high root temperature in symbiotic association with R. japonicum appears to be a feasible alternative to overcome high soil temperature stress and needs to be done in conjunction with strain selection.
Standard, Cold, and Tetrazolium Germination Tests as Estimators of Field Emergence of Mechanically Damaged Soybean Seed1
Authors: Mason S. C. , Vorst J. J. , Hankins B. J. , Holt D. A.
Published: July 2010

Soybean [Glycine max (L.) Merr.] germination is routinely estimated from laboratory germination test results. However, differences in seed quality have caused variable germination performance both in the laboratory and in the field. The objective of this research was to determine ability of standard, tetrazolium, and cold germination tests to estimate average field emergence of mechanically damaged soybean seed. Damaged seeds were subjected to standard, tetrazolium, and cold germination tests and were planted in the field to determine field emergence and seed yield. Germination test accuracy was measured by analyzing the difference between field emergence and the germination test results.

Increasing levels of mechanical damage significantly decreased percent laboratory germination in both years and generally decreased percent field emergence. The tetrazolium test indicated a significantly higher percent laboratory germination than did standard germination and cold tests, and the standard germination test resulted in significantly higher percent laboratory germination than did the cold test. The tetrazolium test was not sensitive in detecting recently induced mechanical damage, and the cold test showed more variability in percent laboratory germination.

In 1975 the standard germination and cold test accurately estimated average field emergence within ± 8 and ± 12%. The tetrazolium test over‐estimated average field emergence from 0 to 20%. In 1976 the standard germination test estimated average field emergence within ± 12%, the tetrazolium test generally over‐estimated average field emergence from 0 to 18%, and the cold test under‐estimated average field emergence by 5 to 41%.
Physiological Response of Chile Pepper to Trickle Irrigation1
Authors: Horton R. , Beese F. , Wierenga P. J.
Published: July 2010

The present field studies were conducted to examine the response of chile pepper (Capsicum annuum L., var. New Mexico No. 6‐4) during one irrigation cycle, to different deficit trickle irrigation treatments.

After applying four different water rates for 46 days, detailed measurements were made, over a 3‐day period between two irrigations, of the water content, the soil‐water pressure potential, the osmotic potential of the soil solution, the leaf water potential, and the stomatal resistance. Crop evapotranspiration was estimated from water balance measurements, and hourly potential evaporation, ET0, was calculated using meteorological information.

There were four water treatments, consisting of a control treatment and three treatments receiving 80, 120 and 140% of the water applied to the control. There were considerable differences in water transpired from the different treatments, but only slight differences in plant water potentials and stomatal resistances. At any time the differences in plant water potential and stomatal resistances were less than 2 bars and 1 sec/cm, respectively. Chile appeared to adapt to the soil water supply by controlling its size. The plants in the dryer irrigation treatments displayed less leaf area, fewer leaves per plant and less aboveground dry mass production. Because of the large differences in plant size associated with relatively small differences in measurements of the plant water status of chile, it appears inadvisable to depend upon pressure chamber, or diffusion porometer measurements for irrigation scheduling of trickle irrigated chile.
Environmental Influences on Fiber Component Concentrations of Warm‐season Perennial Grasses1
Authors: Henderson M. S. , Robinson D. L.
Published: July 2010

Evaluation and management of warm‐season perennial grasses are complicated by seasonal fluctuations in forage quality. Field studies have indicated that a significant proportion of this seasonal variation is due to environmental conditions. Due to confounding effects under field conditions the variation cannot be directly attributed to specific environmental factors. In this study, Coastal and common bermudagrass [Cynodon dactylon (L.) Pers.], Pensacola bahiagrass (Paspalum notatum Flugge), and dallisgrass (Paspalum dilatatum Poir.) were grown in an artificial medium under 4 day/night temperatures (35/24, 32/31, 29/18, 26/15 C), 4 photon flux densities (1,050, 840, 630, 420 µE m−2 sec−1 PAR) and two soil moisture levels (high and low) in growth cabinets to evaluate the relative influence of each factor on fiber component concentrations. Grasses were harvested at 14 and 21 days and analyzed for neutral‐detergent fiber (NDF), acid‐detergent fiber (ADF), cellulose (CEL), hemicellulose (HEM), permanganate lignin (LIG), and silica (SIL) concentrations. multiple regression analysis was used to obtain reduced prediction equations for evaluating responses of all measured variables to temperature (T) and photon flux density (L) at each soil moisture level. Prediction equations for fiber component concentrations of each grass included T effects at both soil moisture levels but did not consistently include L effects. Coefficients of determination (R2 values) for the prediction equations indicated that T and L effects on fiber component concentrations varied with the fiber component, grass, and soil moisture level.

Concentration of NDF increased in the Cynodon species and decreased in the Paspalum species as T increased. In all grasses, predicted concentrations of ADF, CEL, LIG, and SIL increased with increasing T at both soil moisture levels, while HEM concentrations decreased. In all grasses L effects consistently influenced ADF, LIG, and SIL concentrations at both soil moisture levels and CEL concentrations at the low moisture level. Concentrations of ADF, CEL, and SIL decreased slightly, while LIG concentrations increased with increasing L. Although T effects consistently had greater influence in this study, both T and L and their interaction effects significantly influenced predicted fiber component concentrations. The data emphasize the importance of considering environmental influences when evaluating forage quality differences of warm‐season perennial grasses.
Morphological and Physiological Variation in Wild Oat1
Authors: Miller S. D. , Nalewaja J. D. , Mulder C. E. G.
Published: July 2010

Wild oat (Avena fatua L.) is well adapted to grow and persist under a wide range of climatic and edaphic conditions. The present study was conducted to evaluate the variation within the wild oat population in North Dakota and Minnesota as to morphology, dormancy, and herbicide response. Growth characteristics of 230 wild oat accessions and their response to several herbicides for wild oat control were determined. Research was conducted in the glasshouse with potting soil (2:1:1 v/v/v Fargo silty clay, sand, and compost) or field on a Fargo silty clay (fine, montmorillonitic, frigid, Vertic Haplaquolls) or Barnes loam (fine‐loamy, mixed Udic Haploborolls). The wild oat accessions differed in plant height, number of tillers, days to panicle emergence, grain yield, and response to diclofop {2‐[4‐(2,4‐dichlorophenoxy) phenoxy]propanoic acid}, difenzoquat (1,2‐dimethyl‐3,5‐ diphenyl‐1H‐pyrazolium‐ion), flamprop [N‐benzoyl‐N‐(3‐chloro‐4‐fluoropheny1)‐DL‐alanine], and MSMA (monosodium methanearsonate). The accessions were classified into four botanical varieties (ecotypes) based on caryopsis (seed) characteristics; but magnitude classes within the measured traits showed no relationship to the ecotype classification.

Wild oat seed dormancy varied between accessions and was influenced by location and season. The variation in wild oat indicates a potential within the natural population for certain accessions to become more weedy than others especially those possessing high dormancy, herbicide resistance, and seed production.
Quantitative Characterization of Vegetative Development in Small Cereal Grains1
Authors: Klepper Betty , Rickman R. W. , Peterson C. M.
Published: July 2010

The number of headed tillers is an important yield component in cereal grain production. Studies are needed to assess effects of environmental stress and genetic factors on tiller production and abortion in the field. The system for quantifying cereal leaf and tiller development described in this paper permits such studies to be done more definitively than was previously possible because each leaf and tiller on the plant is given a unique designation. The system developed on wheat [Triticum aestivum (L.) em. Thell.] is suitable for other cereals.

Leaves are numbered acropetally, with the first foliar leaf being L1 and the coleoptile L0. Tillers are named for the leaf with which they are associated, e.g., T1 and TO. Subtillers have two digit designations, and third order tillers have three digit designations.

Culm development is described by counting the number of fully expanded leaves and the fraction of the length the newest developing leaf measures relative to its predecessor. A stem with 6.2 leaves has six fully developed leaves and a seventh leaf one‐fifth as long as the sixth.

The developmental time or phyllochron for each leaf on the plant is the same in any given environment, and leaves and tillers unfold in a set and orderly pattern. The rate of this unfolding is primarily determined by environment. Stress causes tillers to be omitted or delayed, compared to unstressed plants.
Cultivar and Seeding Rate Effects on Several Physical Characteristics of Kentucky Bluegrass Turf1
Authors: Brede A. D. , Duich J. M.
Published: July 2010

The growth habit and plant dimensions of Kentucky bluegrass (Poa pratensis L.) can be affected by the management factors imposed. This study was initiated to learn the effects of seeding rate and cultivar on several physical characteristics of Kentucky bluegrass turf and to develop and evaluate techniques for measurement of these characteristics under turf field conditions (a fine, mixed, mesic, Hapludalf soil). An optical enlargement technique was used to measure leaf angle, leaf‐fold angle, sheath‐axis width, leaf width, and leaf length of ‘A‐34’, ‘Baron’, ‘Bonnieblue’, ‘Newport’, and ‘Pennstar’ Kentucky bluegrasses. An overhead projector (the type commonly used in classrooms), mirror, and protractor screen enlarged the plant image 10 to 20 times enabling 1‐degree and 0.05‐mm resolution. A Noer profile sample3 (inner dimension, 13 ✕ 76 mm) was compared to three, round tools and found acceptable for sampling population densities if the loose tillers were included in the count. Because counting was easier and quicker, and plugs were returnable to the plots with minimal disturbance, the Noer tool proved advantageous. A technique was developed for estimating seedling blade density, given a few standheight measurements.

Seeding rate had a positive effect on leaf angle, while the percent loose tillers per sample plug (an indicator of nonvertical tiller orientation), green leaves per tiller, sheath‐axis width, and leaf widths were negatively affected by seeding rate in the year after establishment. Stand densities converged to a mature density over five growing seasons. The convergent density was affected by cultivar and cutting height.

Of the cultivars examined, A‐34 had the highest tiller density throughout the test, fewest green leaves per tiller, and narrowest leaf angle and blades. Baron possessed the most brown leaves per tiller, and widest sheath‐axis width (equal to Bonnieblue). Bonnieblue had the most green leaves per tiller, and lowest mature tiller density (equal to Pennstar). Pennstar had the most loose tillers per sample plug, widest leaf angle, and the most narrow sheath‐axis width.
The Effects of Anhydrous Ammonia at Planting Time on Spring Wheat and Barley1
Authors: Varvel G. E.
Published: July 2010

Anhydrous ammonia has become the main N source used in the northern Great Plains on small grains, but most of it is applied in the fall preceding the crop year. This practice has been used for convenience, to avoid moisture loss which can occur in the spring due to the depth of placement, and to avoid possible germination damage from the anhydrous application if small grains are planted immediately after injection.

The present studies were conducted to determine the effect of anhydrous ammonia on spring wheat, Triticum aestivum L., and barley, Hordeum vulgare L., at planting time.

Field experiments were conducted 1979‐1981 on a Wheatville loam (coarse‐silty over clayey, frigid Aeric Calciaquolls) soil. The treatments consisted of three rates of N as anhydrous ammonia (45, 90, and 135 kg/ha) in 1979 and four rates of N (0, 45, 90, and 135 kg/ha) in 1980‐1981 at three depths (8,16, and 24 cm) in all combinations. Spring wheat and barley were then seeded at three different times. Seedling stand counts, grain yield, and protein were used to determine the effect of the treatments.

Seedling stands were reduced in some cases, but no reduction in grain yield or protein was obtained due to the reduction in stand. The most important factor in spring anhydrous application was the depth of application, which caused greater moisture loss and seedbed disruption at the 24‐cm application depth. Significant responses to N were obtained, but N as anhydrous ammonia did not cause reduction in seedling stands of agronomic importance.