bluuebunny/crossref_metadata_2025 huggingface dataset:
Soil Texture Influence on Applied Nitrogen Recovery1
Authors: Nash Ralph G. , Johnson Donal D.
Published: July 2010

The influence of soil texture on N (nitrogen) recovery from fertilizer NH4+‐N or NO3−‐N by several grass species was determined in the absence of nitrification. Grasses were grown in Terry silty clay soil in which the texture was varied by dilution with sand. The soils were treated with 0, 100, and 200 ppm N and 8 or 24 ppm 2‐chloro‐6 (trichloromethyl)pyridine, a nitrification inhibitor.

Soil texture had no influence on added N recovery from NO3−‐N, but increased N amounts were recovered from the finer‐textured soils when NH4+‐N was the fertilizer source. Nitrogen recovered from the NO3−‐N (78%) source was greater than from NH4+‐N (48%). Lower NH4+‐N recoveries were attributed to NH3 volatilization from these calcareous soils. The nitrification inhibitor probably enhanced the loss of N when applied under the conditions used here.

Nitrate N was accounted for in most cases when the increases in soil N were added to that found in the plants. Only 50% of the 100 ppm rate, and 70% of 200 ppm rate of NH4+‐N, were accounted for by this method. Recovery efficiency of native soil N was less than that of the fertilizer N.
“Runoff Farming” in the Desert. I. Experimental Layout1
Authors: Evenari M. , Shanan L. , Tadmor N. H.
Published: July 2010

An experiment was established to grow fruit trees, field crops and pasture plants in a 100 mm winter rainfall desert region by harvesting surface runoff from small desert watersheds. Experimental conditions and layout are described in the first of a series of papers dealing with the results of the experiment.
Nitrogen and Phosphorus Fertilization for Production of Crested Wheatgrass and Native Grass in Northeastern Montana1
Authors: Black A. L.
Published: July 2010

Nitrogen and N‐P fertilization consistently increased forage yields of native grass and crested wheatgrass (Agropyron desertorum [Fisch.] Schult., ‘Standard’). Plant responses were greatest the year of fertilization, but residual effects were significant 1 to 2 years later. Aplications of N at rates of 45 kg/ha or greater, regardless of P treatment, increased water‐use efficiencies of both grasses 1.5‐ to 2.5‐fold for 2 to 3 years. Increased wateruse efficiency was at least partly due to more efficient extraction of subsoil water. Plant P content was increased substantially by applied P the year of application and 3 years later, regardless of N treatment. Plant recovery of N applied alone at rates of 45 or 90 kg/ha for the 4‐year period averaged 65.8% for crested wheatgrass and 60.0% for native grass. Recovery of N applied in combination with P averaged 73.1% for crested wheatgrass but only 38.2% for native grass. Phosphorus fertilizer stimulated uptake of soil N by both grasses about 20%. Nitrogen increased the 4‐year production of crude protein 1.5‐ to 2.6‐fold for both grasses. High N fertilizer rates were more economical than low N rates, regardless of P treatment.
Plant Absorption of Dieldrin, DDT, and Endrin from Soils
Authors: Nash Ralph G.
Published: July 2010

Wheat seedlings grown in Lakeland sandy loam soils treated with dieldrin‐14C and DDT‐14C absorbed and translocated 14C residues to the shoots. Based upon 14C, dieldrin residues in wheat increased in direct proportion to soil application rate. 14C concentration in wheat was approximately 18% of the soil dieldrin‐14C content, whereas the range of 14C from DDT‐14C was from 3 to 10% of the treated soils.

Soybeans, grown to maturity in endrin‐14C treated Lakeland and Hagerstown soils, absorbed and translocated endrin‐14C to the hay and seeds. Absorption from the Lakeland soil was twice that from the Hagerstowns oil. However, seed residues were essentially the same. 14C equivalent of endrin in the seed was 0.12 ppm. Endrin residues in soybean shoots increased linearly with time. Radioactivity from extracted soybean hay was identical to that of authentic endrin‐l4C, when measured qualitatively by thin‐layer chromatography.
Influence of Night Temperature on Growth and Development of Cotton (Gossypium hirsutum L.). I. Fruiting and Boll Development1
Authors: Gipson J. R. , Joham H. E.
Published: July 2010

Different night temperature regimes were maintained throughout the boll development period on cotton growing in the field during the 1963, 1964, and 1965 seasons. Both fruiting and boll development were found to be closely associated with night temperature. Decreased night temperature resulted in the formation of more flowers and, in some cases, increased fruit set. Relative fruitfulness increased as night temperature decreased between the interval of 21 and 8.8 C and 21 and 14.4 C with ‘Paymaster’ and ‘Acala’ varieties respectively. Temperatures above 19.4 and below 13.3 C reduced fruiting index. Rate of boll development was inversely related to temperature, with a decrease of either day or night temperature resulting in slower boll dvelopment, thus, increasing boll periods. However, in this work night temperature was the dominant environmental factor associated with boll periods. In general, the Paymaster variety appeared to be better adapted to low night temperatures than the Acala variety.
Significance of Fluctuations in Sky Radiant Emittance for Infrared Thermometry1
Authors: Idso Sherwood B. , Jackson Ray D.
Published: July 2010

A theoretical analysis of clear sky radiant emittance in the 600 to 1300 cm−1 waveband showed that this energy flux should be fairly constant over a diurnal period, contrary to some recently reported measurements. New experiments revealed this to be true and indicated that the source of error in the earlier work was due to equipment malfunction. The errors in radiometrically determined surface temperatures caused by neglecting the small variations which do occur were determined to be less than the limits of accuracy of present‐day infrared thermometers in many applications of infrared thermometry to soil and plant research. A nomogram predicted the temperature error to be expected from neglect of clear sky radiant emittance variations for surfaces with temperatures between 0 and 60 C and infrared emittances between 1.00 and 0.90.
A Mechanism for Premature Parenchyma Breakdown in Corn (Zea Mays L.)1
Authors: Liebhardt W. C. , Stangel P. J. , Murdock T. J.
Published: July 2010

Research was initiated to find possible mechanisms causing premature breakdown of parenchyma in the lower third of K‐deficient corn stalks. Three possible mechanisms were postulated. These were: cell wall deterioration, excessive translocation of carbohydrate from storage tissue due to the polarizing effect of the ear, and inhibition of protein synthesis. As a result of fractionation of carbohydrate and nitrogenous components and other experiments with K‐deficient and ‐sufficient corn, it is proposed that the major phenomenon causing parenchyma breakdown is probably the translocation of compounds from the stalk to the ear. This breakdown does not occur unless an ear is present on the plant, therefore, it is proposed that translocation of materials from the stalk to the ear is necessary for the breakdown to take place.
Moisture Use by Selected Forage Crops1
Authors: Cohen O. P. , Strickling E.
Published: July 2010

Soil moisture measurements were made under alfalfa, tall fescue, and bermudagrass, receiving two levels of nitrogen fertilization, and bare fallow. The measurements were analyzed in order to determine the moisture use patterns of the various plants.

All species in this study used approximately the same amount of water during the growing season. Soil moisture loss continued at a nearly uniform rate until approximately 63.5 mm of moisture was used; subsequently, the rate of moisture loss decreased. The growth of the plants was curtailed even though water, in the available range, was present at a depth of 15.2 cm and below. In this experiment, bermudagrass receiving 450 kg of N per hectare produced more dry matter than bermudagrass receiving 112 kg of N per hectare with no significant difference in water consumption. After a rain which did not completely wet the soil profile, moisture was used throughout the whole root zone and not exclusively from the depth wetted by the rain.

The advantages ascribed to deep‐rooted perennial crops with regard to moisture use were not apparent in this study.
Sprinkler and Surface Irrigation of Vegetable and Field Crops in an Arid Environment1
Authors: Robinson F. E. , McCoy O. D. , Worker G. F. , Lehman W. F.
Published: July 2010

Solid set sprinkler irrigation with 3 mm/hour application rate was compared to flood irrigation in a clay soil and to furrow irrigation in a sandy clay loam. Equivalent volumes of water removed greater quantities of salt from the soil profile under sprinklers in the clay soil. Surface salt accumulation was greater under furrow irrigation in the sandy clay loam. Emergence and early growth rates of five field crops were equal or better under sprinkling in the clay soil. Early growth rates of 10 vegetable crops were equal or greater under sprinklers on the sandy clay loam. Final yields indicate the sprinkler irrigation will require more frequent applications than the surface systems. Sprinkler irrigation was shown to have a higher water use efficiency than the surface systems. A change in bed conformity made possible by sprinkling greatly increased the yield potential of vegetable crops.
Comparison of the Effects of Crownvetch (Coronilla varia L.) and Alfalfa Hays on the Liveweight Gain of Sheep1
Authors: Reynolds Paul J. , Jackson Charlie , Henson Paul R.
Published: July 2010

Early cut crownvetch (Coronilla varia L.) and alfalfa hays of similar chemical composition were compared in a 70‐day feeding experiment, using 6‐month‐old crossbred wethers. The two forages in either pelleted or ground form were fed ad libitum as the sole diet. Liveweight gain was greater on alfalfa than on crownvetch and greater on pelleted forage than ground forage. Forage consumption was generally high. Consumption of pelleted forage was considerably greater than that of ground forage. Digestibility of crownvetch was generally less than that of alfalfa. Overall, the lesser liveweight gains on crownvetch were attributable to its lesser digestibility and, in the case of ground forage, to its lesser consumption as well. The differences in digestibility of the structural components of the two forages did not appear to be related to the degree of lignification of lignocellulose.
Effects of Light Intensity, Temperature, and Root Gaseous Environment on Growth of Nicotiana tabacum L.1
Authors: Williamson R. E. , Splinter W. E.
Published: July 2010

The response of Nicotiana tabacum L. plants to various gaseous treatments (O2, CO2, N2) in the root environment was determined by microscopic examination of roots and measurements of stem diameter and leaf area. Superimposed on the gaseous treatments were three environmental energy input levels in which light intensity, air temperature, and nutrient solution temperature were varied. The plants were grown in an artificially lighted, controlled environment room with roots in an intermittent nutrient solution mist in airtight chambers. The roots were treated with gaseous mixtures for 24 hours and then returned to an atmosphere of air for a 5‐day recovery period. Mixtures of 1% O2 in N2, with or without CO2 present, reduced plant growth slightly at 1,000 ft‐c light intensity and 18.3C day temperature, but these mixtures progressively decreased growth as light and temperature increased. At 1,000 ft‐c light intensity and 18.3C day temperature a pure N2 treatment inhibited growth of plants; however, plants slowly resumed growth during recovery. At 4,000 ft‐c light intensity and 29.4C day temperature, N2 treatments killed the root system. Data obtained from measurements of stem diameters, leaf area, root weights, and water use suggest that the survival and growth of plants subjected to poor soil aeration is largely dependent on the ambient temperature and light intensity.
Weather and Technology in the Production of Corn in the U. S. Corn Belt1
Authors: Thompson Louis M.
Published: July 2010

The influence of weather was separated from the influence of technology on the yield of corn by the use of time trends for technology and multiple curvilinear regression for weather variables in five Corn Belt states. A time trend from 1930 to 1960 indicated an average annual increase of 51 kg of grain per ha. A time trend from 1960 to 1967 indicated an average annual increase of 201 kg of grain per ha. Weather variables accounted for most of the variation from the time trends. Average June temperature appeared optimum for corn while below‐average temperatures in July and August were associated with highest yields. Average precipitation from September through June appeared optimum for corn, but highest yields were associated with above‐average rainfall in July. The influence of August rainfall was not significant.
Carrot Population Density and Yield in an Arid Environment1
Authors: Robinson Frank E.
Published: July 2010

Five plant densities of carrots, Daucus carota L. cultivar ‘Long Imperator #58,’ were studied under sprinkler irrigation in the arid Imperial Valley, California. Carrots on a 10‐cm square grid (870,000 per hectare) produced the least dry matter but the earliest roots of marketable size (35 T/ha). Twenty‐five days later plants in a 5.1‐cm square grid (3,370,000 plants per ha) produced both greater dry matter yields and yields of roots of marketable size (94 T/ha). The three greater densities of 13,590,000, 54,390,000, and 223,050,000 plants per ha produced greater dry matter yields but did not reach marketable size. Root‐to‐top ratios were approximately 1:1 in the two greatest densities and 2:1 in the three lowest densities.
Response of ‘Tifgreen’ Bermudagrass and ‘Windsor’ Kentucky Bluegrass to Various Light Spectra Modifications1
Authors: McVey G. R. , Mayer E. W.
Published: July 2010

Windsor Kentucky bluegrass (Poa pratensis, L. ‘Windsor’) and Tifgreen bermudagrass (Cynodon dactylon, L. ‘Tifgreen’) were grown under transparent, acrylic plastic panels during the summermonths (June 1 to oct. 1, 1966) under outdoor conditions. Various acrylic plastic units were selected with the transmittance in the blue (410.510 mµ) ranging from 18 to 74% of full sunlight and in the grey (390‐760 mµ) ranging from 15 71% of full sunlight.

Turfgrass color and quality (aesthetic value) were increased and clipping length and fresh weight removal reduced when bluegrass and bermudagrass were exposed to blue light as compared to grey light, at comparable light transmittance levels. These differences were more striking at the lower light intensities (less than 60% transmittance).

Seedhead formation of bermudagrass was stimulated when the grass was grown under blue‐tinted acrylic plastic and suppressed when grown under grey‐tinted acrylic plastic.

The degree of injury (as reflected by turf density) was not markedly altered by light quality except at very low light intensities. Bermudagrass was severely injured when grown under grey‐tinted acrylic plastic with less than 20% transmittance while turf grown under blue‐tinted acryfic plastic at low light intensities was only slightly injured.

The minimum light quantity for acceptable turf quality of Tifgreen bermudagrass and Windsor Kentucky bluegrass should exceed 40 to 50% transmittance of the full sunlight if the turf is grown in blue transmitted sunlight or 60 to 70% transmittance if grown in grey transmitted sunlight.
Composted Municipal Refuse: Its Effects on Carbon Dioxide, Nitrate, Fungi, and Bacteria in Arredondo Fine Sand1
Authors: Rothwell D. F. , Hortenstine C. C.
Published: July 2010

Effects of high levels of garbage compost, chicken manure, cow manure, and sewage sludge on microbial activity in Arredondo fine sand were evaluated by determination of relative numbers of bacteria and fungi, CO2 evolution, and nitrification. With each increase in garbage compost, relative fungal numbers increased at each measurement period; bacterial numbers increased, then decreased rapidly by the 4th or 6th day. The amount of cumulative CO2‐C evolved by these materials when mixed with soil was: cow manure < garbage compost < chicken manure < sewage sludge. Similar relationships were obtained when garbage compost was mixed with cow manure, chicken manure, or sewage sludge and added to soil. Nitrification decreased with increased levels of both sewage sludge and chicken manure and increased with increased levels of cow manure. However, little nitrification occurred when cow manure was mixed with equal quantities of garbage compost. Only slight nitrification occurred when the soil was amended with garbage compost.
Dry‐Matter Accumulation in Corn (Zea mays L.) Plants: Comparisons among Single‐Cross Hybrids1
Authors: Hanway J. J. , Russell W. A.
Published: July 2010

Eleven corn (Zea mays L.) hybrids were grown in the field for determination of dry matter accumulation in the different plant parts at successive stages of plant development. The length of time from stage O (emergence) to stage 2.5 (10th leaf fully visible) was the same for all hybrids, but the length of time from stage 2.5 to stage 5.0 (silking) and the length of time during which the grain increased in weight varied markedly among the hybrids. The daily rate of dry matter accumulation was similar for all hybrids. The relative proportion of grain and nongrain plant parts varied among the hybrids. Dry matter apparently accumulated in many nongrain parts of the plants after silking and was later translocated to the grain.
Relative Precision of Different Experimental Designs and Number of Replications in Pea Yield Trials1
Authors: Zuhlke Thomas A. , Gritton Earl T.
Published: July 2010

The relative efficiency of simple, triple, and balanced lattice designs relative to randomized complete blocks for fresh‐shelled pea yield trials was estimated from uniformity trial data. Lattices were always equal to or more efficient than randomized complete blocks, ranging from 100% with some short wide plots in the smaller block sizes to 236% for a long narrow plot with a block size of seven.

The minimum detectable true difference as a percent of the experiment mean is given for several treatment, replicate, and plot size and shape combinations. The importance of minimizing experimental variability is demonstrated.
Corn Yields, Soil Temperature, and Water Use with Four Tillage Methods in the Western Corn Belt1
Authors: Olson Tamlin C. , Schoeberl LaVern S.
Published: July 2010

Corn grown with four systems of tillage (conventional, wheeltrack planting, till planting, and listing) was compared for yield and several growth characteristics. Yields from the three reduced‐tillage systems in 1965, 1966, 1967, and 1968 were at least as good as those from the conventional system. The four tillage methods created a wide range of soil conditions, so that differences in growth and yield indicate the range of response that can be expected from tillage for the seasons experienced. Because of below normal rainfall, corn was under stress during flowering and ear formation in each of the four years. Soil temperature at seed depth was lowest in the listed plots where corn was planted in the bottom of the furrow. Although this resulted in slower plant growth, the delayed maturity was not correlated with final yield of dry grain or total dry matter. No significant difference among tillage systems in either total water use or in the pattern of water use was detected.
Effect of Cropping Systems and Nitrogen Levels on Corn (Zea mays) Yields in the Southern Piedmont Region1
Authors: Adams William E. , Morris H. D. , Dawson R. N.
Published: July 2010

A field experiment was conducted on Cecil sandy loam over a 7‐year period to determine the effect of cropping systems and nitrogen levels on corn (Zea mays L.) yields. Green manure crops and perennial grass or legume sods increased corn yields regardless of the level of N fertilization. Removal of corn stalks did not decrease corn yields when corn was grown continuously with or without annual green manure crops. Alfalfa (Medicago sativa L.) and tall fescue (Festuca arundinacea Schreb.) were equally effective in sod‐based rotations for corn. Coastal bermudagrass (Cynodon dactylon (L.) Pers.) was slightly less effective in sod‐based rotations because it competed with corn during the growing season. The beneficial effect of sod on corn yields lasted for at least 4 years after the sod was turned.
Influence of Tillage Management in a Stubble Mulch Fallow‐Winter Wheat Rotation With Herbicide Weed Control1
Authors: Oveson M. M. , Appleby Arnold P.
Published: July 2010

Studies were conducted near Pendleton, Oregon, from 1962 through 1965 to compare the effect of no‐tillage and various times of stubble mulch tillage operations during the fallow season on moisture storage, nitrate accumulation, and winter wheat (Triticum aestivum L.) yields. Weeds were controlled during the spring and summer of the fallow year with nonpersistent herbicides. Plots which had received no tillage tended to store less moisture and to accumulate less nitrates than tilled plots. During the second crop year, yields from nontilled plots were significantly reduced compared to yields from tilled plots. Conventional stubble mulch tillage including two or three rod weedings tended to be the optimum tillage treatment. Delaying the first tillage until June decreased moisture storage in comparison to other tillage treatments.
Influence of Early Lodging on Yield of Soybean [Glycine max (L.) Merr.]1
Authors: Cooper Richard L.
Published: July 2010

The effect of early lodging on the yield of ‘Wayne’ soybeans (Glycine max (L.) Merr.) was studied in highly productive and lodging conducive environments at Ashland and Chenoa, Ill. A wire grid system was suspended horizontally over the treated plots to prevent lodging and permit development of undisturbed canopies. The check plots were permitted to lodge naturally. Two row spacings and three plant populations were used.

Natural lodging occurred at early pod set (early August); and by mid‐pod fill (late August) lodging had reduced the canopy height by 46% at both locations (150 vs 81 cm at Ashland and 131 vs 71 cm at Chenoa). Seed yields in the lodged plots were reduced 21% at Ashland (47 vs 37 kg/are) and 23% at Chenoa (35 vs 27 kg/are). There were no significant interactions between treatment and spacing or population.
Effect of Photoperiod and Temperature on the Development of Sorghum1
Authors: Caddel J. L. , Weibel D. E.
Published: July 2010

Three varieties of Sorghum bicolor (L.) Moench, (i.e., ‘Early Hegari,’ ‘80‐Day Milo,’ and ‘Wheatland’) were grown in controlled environment chambers and subjected to all combinations of 10‐, 12‐, and 14‐hour photoperiods, 27 and 32 C day temperatures, and 16 and 21 C night temperatures. Days to floral initiation were determined for each variety under each treatment combination. In addition, days to anthesis and days in the floral period (from initiation to anthesis) were determined for the treatment combinations involving 21 C night temperatures.

Ten‐hour days hastened floral initiation and anthesis of each variety at all temperature combinations. Fourteen‐hour days delayed development, but with some temperature regimes the delay was not significant, compared to the shorter days. The rate of development for the varieties under 12‐hour days was highly dependent upon day and night temperatures, since floral initiation ranged from as early as that obtained with 10‐hour days to later than that obtained with 14‐hour days.

The response to day temperature during the floral period was small, but statistically significant. The time to anthesis followed a pattern similar to that for the time to floral initiation.
Yield of Wheat and Soybeans and Oil and Protein Content of Soybean as Affected by Fertility Treatments and Deep Placement of Limestone1
Authors: Jones G. D. , Lutz J. A.
Published: July 2010

Plow sole placement (30.5 cm deep) of dolomitic limestone at rates of 0, 22.4, and 44.8 mt/ha was compared with wheat (Triticum aestivum) grown on Tatum silt loam in 1969 and followed by soybeans [Glycine max (L.) Merrill] in 1970. Treatments consisted of 0, 12.2, 24.4, and 48.8 kg P/ha without K; 24.4 and 48.8 kg P/ha with 23 kg K/ha; and 48.8 and 97.6 kg P/ha with 46 kg K/ha with each rate of lime. The P and K treatments were surface‐applied and disced in.

Wheat and soybean yields were increased by P and K treatments but not by deep lime placement. Placement of lime on the plow sole increased the oil content from 23.02 to 23.49% but did not affect the protein content of the soybeans. Differences among P and K treatments in oil and protein contents of the soybeans were highly significant. The P contents of soybean leaves were unaffected by deep lime placement, but the K contents of soybean leaves were decreased with increased lime rate.
Relationships of Vigor Tests and Seed Source and Size to Sorghum Seedling Establishment1
Authors: Abdullahi Ango , Vanderlip R. L.
Published: July 2010

Conditions provided in standard seed germination tests are regarded as too “ideal,” and better methods of evaluating the seeds' capacity to germinate under less “ideal” field conditions are needed. In this study, vigor tests involving artificial aging of seeds, soil cold test, soaking of seeds in NH4Cl, as well as standard germination, were compared to determine their correlation with field seedling establishment of grain sorghum [Sorghum bicolor (L.) Moencb]. All the tests showed significant correlations with seedling establishment in the field, but the NH4Cl treatment gave better correlations. Effects of seed source and size on vigor and field establishment of seedlings were also determined. Both factors were important in determining germination and field seedling establishment. Large seeds tended to perform better in the laboratory tests than in the field. Results between laboratory and field conditions were more consistent with medium or small seeds. Significant source ✕ size interactions in both laboratory germinations and seedling establishment in the field indicated that the effects were not due to seed size per se.
Evapotranspiration from Soybean and Sorghum Fileds1
Authors: Brun Lynn J. , Kanemasu Edward T. , Powers William L.
Published: July 2010

The evapotranspiration model, presented by Monteith (1965) and later tested by Black et al. (1970) on a loosely structured snap bean (Phaseolus vulgaris) canopy, was used to separate soil evaporation and transpiration on soybean [Glycine max (L.) Calland] and sorghum [Sorghum bicolor (L.) Pioneer #846] canopies during the growing season.

Soil evaporation was estimated as the net radiation below the crop canopy minus the soil heat flux. Stomatal resistance was determined with the diffusion porometer (Kanemasu et al. 1969). Potential evapotranspiration, soil evaporation, and transpiration rates were determined on an hourly basis. The sum of transpiration and soil evaporation was compared to the lysimetric estimates of evapotranspiration.

The model and the lysimeters were in agreement, except under conditions of high atmospheric demand when the model underestimated actual evapotranspiration.

The model showed the proportion of water lost as transpiration was closely correlated to leaf area index (LAI) with transpiration at approximately 50% of the total evapotranspiration at a LAI of 2 and as much as 95% at a LAI of 4.
Germination and Establishment of Salsola in Relation to Seedbed Environment. II. Seed Distribution, Germination, and Seedling Growth of Salsola and Microenvironmental Monitoring of the Seedbed1
Authors: Evans Raymond A. , Young James A.
Published: July 2010

The purpose of this study was to ascertain when and under what conditions seed germination and seedling growth of Russian thistle (Salsola kali var. tenuifolia Tausch.) occurs in the field. Continuous monitoring of temperature and moisture parameters of the seedbed microenvironment was conducted during critical periods of germination and seedling growth. Seedling emergence was sampled weekly concurrent with seedbed monitoring. Seed dispersal investigations and seedling emergence studies in relation to burial depth were also carried on. Seed germination and seedling emergence of Russian thistle commenced in midwinter and early spring with below 0 C night temperatures alternating with 10‐ to 19‐C day temperatures. Optimum emergence occurred in March, with temperatures of 0 to 5 C alternating with those of 12 to 25 C. Afterripening requirements curtailed germination of 1970 seeds, compared with those of 1968, at early dates, but by March no depression occurred. Soil moisture potentials less than —15 bars reduced seedling emergence and increased mortality. Low relative humidity at the soil surface during the day curtailed establishment of plants from surface seeds. Seed burial, litter cover, and variable microtopography were all conducive to establishment of Russian thistle.
Nitrogen Nutrition of Field‐grown Soybean Plants: II. Seasonal Variations in Nitrate Reductase, Glutamate Dehydrogenase and Nitrogen Constituents of Plant Parts1
Authors: Streeter John G.
Published: July 2010

The goals of this portion of the study were to determine (a) the distribution of N compounds in the aboveground portion of soybean plants and (b) fluctuations in the capacity for N assimilation in the leaves. Soybean plants (Glycine max (L.) Merr., ‘Harosoy 63’) grown der field conditions were sampled at 14 growth stages for the determination of dry weight, total N, amino N and nitrate N of leaves, stems, and fruits. Nitrate reductase activity and glutamate dehydrogenase activity in leaves were determined at 13 harvest dates. Free amino acid content of leaves, stems, and fruits was determined for one replicate and 13 harvest dates.

Amino N was only 2 to 6% of total N in stems and leaves at most harvests indicating that amino acids transported to the tops are rapidly converted to protein. However, up to 40% of the N in stems was in the form of nitrate at the earliest harvests but this proportion fell rapidly to 5% in the flowering stage and to zero in later stages of development. Nitrate reductase content of the leaves was also highest preceding flowering while glutamate dehydrogenase showed the opposite trend, increasing four‐fold from the flowering stage to latter stages of seed development. Seasonal averages indicated that asparagine was the predominant free amino acid in stems and fruits. Asparagine content of leaves decreased approximately 20‐fold and stems 100‐fold from the first to the thirteenth harvest. The N nutrition of the soybean plants in this experiment appeared to be dependent on nitrate assimilation prior to flowering, but strongly dependent on the assimilation of ammonia from N fixation from the flowering stage to maturity.
Use of Rubidium as a Chemical Tracer for Potassium in Long‐term Experiments in Cotton and Barley1
Authors: Hafez A. , Rains D. W.
Published: July 2010

Considerable controversy surrounds the technique of using Rb to chemically or isotopically label K. A series of experiments were conducted to determine the usefulness of this technique when other, potentially interactive, ions are present in the media and the plants are exposed to these solutions for extended periods.

Cotton (Gossypium hirsutum var. ‘Acala, SJ‐1’) and barley (Hordeum vulgare var ‘Arivat’) were grown in the greenhouse for 45 days in culture solutions containing various ratios of Rb/K. Na and NH4 were added to determine the extent of the interaction of these cations with Rb and K.

The distribution of Rb and K in different plant parts was determined chemically at the end of the growth period. Quantitative tagging of Rb for K depends upon factors of ionic concentration of both ions, the ratio of Rb/K in the substrate, plant species, and the presence of other monovalent cations, such as NH4 or Na ions.

Roots of both cotton and barley plants retain Rb preferentially over K. Ammonium ions compete more with K than with Rb uptake. Cotton blades reflect the Rb/K ratios of the culture solution, with a maximum deviation of 20% over the fiftyfold range of K concentration examined.
Digestibility of Bloom and Bloomless Sorghum Leaves as Determined by a Modified In Vitro Technique1
Authors: Cummins D. G. , Dobson J. W.
Published: July 2010

Forage quality of three near‐isogenic lines of sorghum [Sorghum bicolor (L.) Moench], differing primarily in the bloom and bloomless characteristic, was studied. The bloom type has a white, powdery‐appearing wax on the surface of the leaves and stems not present on the bloomless type. In vitro dry matter digestibilities (IVDMD) were determined by a modified in vitro technique on 10.2‐cm green‐leaf segments and conventionally on similar material dried and ground. IVDMD of green leaves was 22% higher on the bloomless type compared to the bloom type, with little difference between types from the samples dried and ground. These results suggest that the bloom reduced IVDMD, and that quality of sorghum forage may be improved by selecting for the bloomless characteristic. The potential of an IVDMD technique utilizing green‐leaf segments is demonstrated by these results.
Influence of Fertilizer Placement on Yield Response of Soybeans1
Authors: Ham G. E. , Nelson W. W. , Evans S. D. , Frazier R. D.
Published: July 2010

Placement of fertilizer in relation to the seed of most agronomic crops has been studied extensively. Limited information is available concerning the placement of fertilizer for soybeans.

Fertilizer treatments consisting of banded starter, starter in contact with the seed, and a combination of banded and seed placement were superimposed on broadcast fertilizer treatments at three locations. Responses varied depending on environmental factors. With low rainfall and a low soil test P level, the largest response was from broadcast fertilizer. Starter fertilizer had less effect on seed yields either with or without broadcast fertilizer even though both starter and broadcast effects were significant. With adequate rainfall and a low P level, the largest response was to combinations of starter and broadcast fertilizer. Yields were increased by as much as 746, 598, and 941 kg/ha with band, seed placement and broadcast treatments, respectively. When P and K levels were very high, no yield increases were obtained from any fertilizer placement. In fact, seed placement without broadcast or seed placement and/or band in combination with broadcast decreased yields significantly in many cases. Three soybean [Glycine max (L.) Merrill] varieties were used at each location and the responses were different depending on varieties. The largest yield increases were obtained with ‘Corsoy’ and ‘Hark’ varieties.
Excess‐Base and Excess‐Base/Nitrogen Ratio of Various Crop Species and Parts of Plants1
Authors: Pierre W. H. , Banwart Wayne L.
Published: July 2010

The primary objective of this study was to determine how various crop species differ in their cation‐anion balance and thus in their effects on soil reaction and on the acidifying effects of N fertilizers on the base status of soils. Samples of 27 species of cereal, grass, legume, and miscellaneous field and vegetable crops were collected from a wide range of environmental conditions in the field. The plants were analyzed for total N, nitrate N, and excess‐base (EB); and calculations were made of excess‐base/organic N ratios (EB/N). Similar determinations were also made on the principal plant parts of 13 crop species.

Marked differences were found in the excess‐base of the various crop species. The average EB ranged from 30 meq/100 g for wheat (Triticum aestivum L.) to 213 meq/100 g for tobacco (Nicotiana tabacum L.). In general, monocotyledons were lower in EB than dicotyledons. Likewise, crop species showed distinctive differences in EB/N ratios, ranging from 0.24 for cabbage (Brassica oleracea capitata) to 1.09 for buckwheat (Fagopyrum esculentum).

Samples of a given crop species grown under a wide range of environmental conditions showed considerable range in EB and EB/N ratios. For most crop species the coefficients of variation of EB/N ranged from 10 to 20%.

The principal plant parts of a given crop species showed in many instances moderate to large differences in EB and EB/N. Thus, differences in the proportion of plant parts in different samples may affect the EB and EB/N of a given species.

The significance of the differences in the EB/N of various crop species in modifying the effect of N fertilizers on soil acidity is discussed.
Ammmonium and Nitrate Uptake by Corn (Zea mays L.) as Influenced by Nitrogen Concentration and NH+4 /NO‐3 Ratio1
Authors: Warncke D. D. , Barber S. A.
Published: July 2010

Corn (Zea mays L.) absorbs both ammonium and nitrate forms of N. Both are usually present in the soil and some control of their proportions can be obtained by controlling nitrification. Little is known about the relative rates of absorption of these ions or their effect on plant growth rate when both are present. We investigated the effects of NH4+ and NO3− on corn by growing 13‐day‐old corn seedlings for an additional 5 days in 25 nutrient solutions consisting of 5 N concentrations (15.9, 67.1, 303, 1507, and 6015 μM) at each of 5 NH4+/NO3− ratios (8.40, 2.46, 1.05, 0.49, and 0.17). Solution NH4+, NO3−, and pH were monitored and variations kept to a minimum. Uptake rates of NH4+ and NO3− were estimated separately from solution analysis. Maximum dry matter accumulated with an N concentration of 67 μM. Maximum N uptake occurred for the combination of 303 μM N and a NH4+/NO3− ratio of 2.46. Shoot/root ratio increased significantly with increased N concentration, but was unaffected by NH4+/NO3− ratio. Above 67 μM N, the NH4+/NO3− ratio of absorbed N tended toward 1.0 as compared with the ratio in solution. There was no significant difference between NH4+ and NO3− in their relative rates of absorption. Increasing the concentration of NH4+ reduced the NO3− uptake rate and increasing the NO3− concentration reduced the NH4+ uptake rate. Each mutually influenced the absorption of the complementary nitrogen form to the same degree.
Effect of Planted Seed Size on Emergence and Yield of Soybeans (Glycine Max (L.) Merr.)1
Authors: Johnson D. R. , Luedders V. D.
Published: July 2010

The effect of planted seed size on emergence and yield was evaluated in the field with four soybean (Glycine max (L.) Merr.) cultivars (‘Amsoy 71’, ‘Beeson,’ ‘Calland,’ and ‘Clark 63’) in 1971 and 1972. Seed from each cultivar was divided into three sizes. These plus a mixture of all three seed sizes were tested. Seed sizes varied from 130 to 250 mg/seed and had no effect on emergence or yield. These was a significant difference among cultivars in emergence and yield, but the seed size by cultivar interaction was nonsignificant.
Yield of Alfalfa as Related to Carbon Exchange1
Authors: Delaney R. H. , Dobrenz A. K.
Published: July 2010

Photosynthetic rate has not proved to be an effective selection tool for forage yield in alfalfa (Medicago sativa L.). A consistantly positive correlation between yield and photosynthesis, when expressed on a leaf area and leaf weight basis, of individual plants has not been established. Since the leaf area per plant often confounds yield and carbon exchange research, this study was conducted to evaluate individual genotypes for potential total CO2 incorporation. This method of expressing photosynthesis would combine the effects of genotype variability in photosynthetic rate per unit leaf area and total leaf area per plant.

Two clones which previously exhibited high photosynthetic rates and two clones with low photosynthetic rates per unit leaf area were selected from the cultivar ‘Mesa‐Sirsa’ and were transplanted into an established alfalfa field in order to obtain a normal plant population in the field experiment. Data were collected on two harvest dates. In the controlled experiment 146 plants from the alfalfa population MSE‐6 were grown in individual pots. Photosynthesis was measured at light intensities of 22 and 44 klux for two stages of growth. Dark respiration was also determined.

Carbon exchange data were expressed on a leaf area, leaf dry weight, and per plant basis. Significant positive correlations were observed between photosynthesis expressed on a leaf weight and leaf area basis; however, these expressions of carbon exchange were not significantly related to total CO2 uptake per plant. Forage yield was significantly correlated (r=.96“* and .93”*, the first and second harvests, respectively) with total apparent photosynthesis per plant but not with photosynthesis expressed on a leaf weight and leaf area basis m the field study. Photosynthesis was also significantly associated with forage yield in the controlled environment experiment. Total dark respiration per plant after 25 days of regrowth was found to be highly correlated (r=.85**) forage yield. The apparent photosynthesis to dark respiration ratio was not associated with forage yield. The data from these studies suggest that the total CO2 uptake limits alfalfa forage production more than carbon exchange per unit leaf area.
Comparative Reduction of Calcium and Magnesium Composition of Corn Tissue by NH4‐N and K Fertilization1
Authors: Claassen Maria Elena , Wilcox G. E.
Published: July 2010

Ammonium‐N nutrition in nutrient culture has been shown to reduce Ca and Mg uptake to near‐deficient levels in many plants. The addition of K to soils also reduces Ca and Mg contents of plants. Since NH4‐N is often present during the seedling growth period of plants a study was set up on soils with high and low exchangeable Ca and Mg levels to determine the comparative effect of NH4‐N and rate of K on Ca and Mg absorption by corn (Zea mays L.) plants. Knowledge of these effects could be of benefit in formulating fertilizer programs in crop production where Ca and Mg content is a factor in forage or crop quality.

A greenhouse study was conducted to compare the influence of N form and K levels on the absorption of Ca and Mg by corn plants grown in Princeton sand with 67 kg Mg/ha and Fincastle silt loam with 800 kg Mg/ha. The treatments used were 100 ppm N as NH4 or NO3, and 0, 50 and 100 ppm K in factorial design. Aerial portions of the plants were analysed for N, P, K, Ca, and Mg.

Increasing levels of K in the soils under NO3 nutrition reduced the concentrations of Ca and Mg in the corn tissue. However, NH4‐N at the zero K rate reduced Ca and Mg concentrations in the corn tissue to less than that at the highest K rate with NO3‐N. K rate did not significantly change Ca or Mg uptake under NH4 nutrition on either soil. The exchangeable Mg level of the soil directly affected the Mg composition of the tissue with both NO3‐N and NH4‐N nutrition. The ammonium‐N source reduced Mg uptake by corn on the soil with exchangeable Mg of 67 kg/ha to a deficient level of less than 0.20% in this tissue, which is the critical Mg level of forage associated with incidence of hypomagnesemia in ruminant animals. Thus NH4‐N must be considered an important factor in its influence on cation concentration of tissue grown on low Mg soils during periods when NH4‐N is the predominant N source.
Water Uptake by Seeds as Affected by Water Stress, Capillary Conductivity, and Seed‐Soil Water Contact. I. Experimental Study1
Authors: Hadas A. , Russo D.
Published: July 2010

Imbibition and seed germination as affected by water potentials, hydraulic conductivity, and seed‐water contact area were studied. Water potential effects Were studied under perfect seed contact and unlimited hydraulic conductivity. Effects on imbibition and germination of hydraulic conductivity and seed‐water contact were studied in an experimental setup in which separation between these factors was made possible while a very high water potential was maintained. The results show that low values of external water potential affect the rate of water uptake but not percent of germination. The rate of germination, however, is affected as long as water potential is higher than a critical value that is speciesspecific. For a given seed‐water contact area, any decrease in the hydraulic conductivity (or for a given conductivity, any reduction in contact area) reduced rates of water uptake and germination; total germination was not affected as long as the critical water potential was not reached.
Effects of Weed Control and N Fertilization at Establishment on the Growth and Nodulation of Alfalfa1
Authors: Kunelius H. T.
Published: July 2010

The establishment of productive alfalfa (Medicago sativa L.) stands is greatly dependent on competition by other plant species and on the seedling development of the forage legume. The objective of this study was to determine the effects of weed control methods in combination with N fertilization rate on seedling growth and nodulation of alfalfa. ‘Saranac’ alfalfa was established on check (no weed control), handweeded, and herbicide 4‐(2,4‐ dichlorophenoxy)butyric acid + 2,2‐dichloropropionic acid (2,4‐DB ‐f‐ dalapon) plots with N applied at 0, 25, 50 or 100 kg/ha at emergence of the forage legume. Dry matter (DM) yields of alfalfa in the first cutting were significantly increased by N applications of 25 to 50 kg/ha over the check in two out of three experiments. Nitrogen applied at seeding did not influence the DM yields of the second cutting. On plots treated with 2,4‐DB and dalapon, the DM yields of alfalfa in the first cutting were 30 to 81% and 11 to 78% of those of check and handweeded plots, respectively. In the second cutting, DM yields of alfalfa were not affected by the method of weed control. Weed growth was significantly increased by applied N in one experiment only.

Nodule size was reduced by N applications of 50 and 100 kg/ha. Similarly, the number of nodules per plant was decreased in one experiment. Percent total N of alfalfa tissue was increased by applied N in the first cutting of two experiments. In the second cutting, high N rates resulted in a lower N content of alfalfa tissue which coincided with poor nodulation. The N rate ✕method of weed control interactions for most criteria were not statistically significant.
Physical Characteristics of Soil Mixtures Used for Golf Green Construction1
Authors: Brown K. W. , Duble R. L.
Published: July 2010

Large amounts of money are invested each year in the preparation of mixtures for the construction of golf greens and athletic fields. Few efforts have been made to completely characterize the physical properties of the resulting greens. Therefore, a greenhouse experiment was conducted to determine the physical characteristics of a range of sand and soil mixtures for golf green construction. Treatment variables included the amount and texture of soil used in the mixture and the presence or absence of a sand layer between the mixture and the gravel drainage layer. The mixtures were placed in 30 cm diam. containers.

They were compacted and grass was established. Infiltration rates decreased after the grass was established and decreased again after the soil mixture was compacted. Mixtures with greater than 3% clay had infiltration rates too small to assure a playable surface after heavy water applications. The depth of available water held by mixtures with 5% soil averaged 6.6 cm for a 35 cm layer. Pure sands held about half this amount of water. Measured water retention agreed well with that calculated from the unsaturated conductivity of the gravel layer and the water retention characteristics of the mixture. Provided the gravel used as the drainage layer has a particle distribution such that less than half the particles are greater than 0.64 cm, little evidence of particle migration was found even without a layer of sand between the mixture and the gravel. Optimum physical characteristics were achieved with mixture containing 5% soil, 85% sand, and 10% peat moss by volume.