bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaporation and Condensation on Bare Soil under Irrigation in the East Central Great Plains1
Authors: Rosenberg Norman J.
Published: July 2010

Evaporation from bare Sharpsburg s.c.l. was measured with precision weighing lysimeters at Mead, Nebr., during summer and fall, 1966. A number of drying cycles were included. Maximum daily evaporation was about 9 mm/day in August and about 3 mm/day in late October. The ratio E/Rn was frequently greater than unity especially when the lysimeters and a 1‐ha area surrounding them was visibly wet and the surface of the adjacent fields dry. A significant advectional contribution of energy in indicated. Nocturnal evaporation accounted for 10 to 50% of the total daily evaporation, the greater proportions occurring in fall. Dew was detected almost every morning. A maximum dew deposition of about 0.5 mm was measured. The Penman method yielded lower estimates of bare soil evaporation than did van Bavel's combination method. Both types of estimates varied from lysimetrically measured evaporation by from 3 to 50% on a daily basis.
Moisture and Temperature Effects on Emergence and Initial Growth of Two Range Grasses1
Authors: Herbel Carlton H. , Sosebee Ronald E.
Published: July 2010

This research, conducted in controlled light‐temperature chambers, studied the effects of two temperature regimes and five moisture levels on early growth of black grama (Bouteloua eriopoda (Torr.) Torr.) and boer lovegrass (Eragrostis chloromelas Steud.). The maximum daily soil temperatures ranged from 53 to 67C in the high temperature regime, and from 38 to 51 C in the low temperature regime, depending on moisture level. The daily minimum temperatures were about 25C in all treatments. The five soil moisture levels were determined as a portion of the volume required to maintain field capacity conditions. Level A was approximately field capacity; levels B and C were watered as level A on the planting day, and then reduced to about a half and a third of level A for the remainder of the 21‐day trial. Levels D and E were watered as level A for the first 3 days, and then reduced to about a half and a third of level A for the remainder of the trial.

In the high temperature regime black grama did not emerge at moisture levels B and C; and boer lovegrass did not emerge at levels B, C, and E. In addition, boer lovegrass did not emerge in the low temperature regime at moisture level C. Survival of emerging seedlings ranged from 0 to 4.7% in the high temperature regime at all moisture levels except A. Reduced soil moisture, a day after planting, was more detrimental to survival than reducing soil moisture the third day after planting. Survival of black grama at moisture level A in the high temperature regime was not adversely affected by the high leaf temperatures (81C). The shoot lengths and weights of surviving black grama seedlings were always greater than those of boer lovegrass. Survival and growth of seeded species in the Southwest would be enhanced if soil temperatures and evaporation from the soil surface were reduced. Under the conditions of this 21‐day trial it took about 70 mm of water for either species to survive in the low temperature regime and about 231 mm to survive in the high temperature regime
Nitrogen, Phosphorus, and Potassium Fertilization of Non‐Tilled Maize1
Authors: Triplett G. B. , Van Doren D. M.
Published: July 2010

No‐tillage and conventional tillage (plow, disk, cultivate) were used for corn grown in monoculture for 6 years with three rates of nitrogen fertilization. Phosphorus and potassium were applied uniformly each year with the planter and as surface bulk applications during 2 years of the study. Grain yields were higher for notillage than for conventional tillage treatments at all N levels.

Most of the P applied to the soil surface between rows of no‐tillage treatments remained in the surface 2.5 cm of soil. K was also concentrated near the soil surface. P and K concentration in leaves of maize grown without tillage were equal to plants grown with conventional tillage when sampled at tasseling and significantly higher when sampled at the 8 to 10 leaf stage.
Kenaf (Hibiscus cannabinus L.), A Multi‐use Crop1
Authors: Killinger G. B.
Published: July 2010

Possible new economic uses for kenaf (Hibiscus cannabinus L.) include feed for livestock, paper‐pulp, and bean poles. The crude protein content of 55‐day‐old kenaf leaves and petioles exceeds 25% and for the whole plant, excluding roots, averages 16 to 17%. Kenaf has been found acceptable as a paper‐pulp or as a pulp to be blended with wood pulp. Yields of 20,000 kg/ha of dry kenaf stems are produced in the South with slightly lower yields in South Central and Central states. Kenaf is susceptible to root‐knot nematodes (Meloidogyne incognita and M. incognita acrita) and should be grown on soil free of these organisms. Intake of kenaf silage, experimentally by cattle, has been satsifactory, however sheep have not liked it as silage.
Siberian Wildrye (Elymus sibiricus L.): Agronomic Characteristics of a Potentially Valuable Forage and Conservation Grass for the North1
Authors: Klebesadel L. J.
Published: July 2010

Siberian wildrye (Elymus sibiricus L,), a tall‐growing, perennial bunchgrass native to Europe and Asia, has a recently confirmed distribution in northwestern Canada and Alaska. New range extensions are reported here. Agronomic evaluations with the North American ecotype in south‐central, subarctic Alaska revealed good seedling vigor, excellent winter hardiness and forage yield potential, and outstanding seed production capacity. Seeds with awns removed numbered 304,000/kg (138,00O/lb). Increased use of this grass for forage production and conservation purposes in the North appears likely.
Turfgrass Evapotranspiration1
Authors: Tovey Rhys , Spencer John S. , Muckel Dean C.
Published: July 2010

The evapotranspiration of turfgrasses grown on loam and sandy loam soils in lysimeter tanks was measured for three growing seasons. The irrigation schedules were set to approach drought conditions. Twice weekly irrigation was necessary to permit lawngrass grown on sandy loam soil to maintain good appearance during hot weather. Once a week irrigation was sufficient to maintain lawngrass in the same manner when grown on loam soil. Once a week irrigation sustained Tifway and Tifgreen bermudagrasses on both loam and sandy loam soils. The quantity of water applied in each case was 5.08 cm (two surface inches) per week, enough to bring the root zone to field capacity at each irrigation. Evapotranspiration was compared with pan evaporation, net radiation, and the Olivier and Penman methods. Monthly Blanev‐Criddle coefficients were also determined.
Autumn‐Saved Coastal Bermudagrass (Cynodon dactylon (L.) Pers.): Effects of Age and Fertilization on Quality1
Authors: Hart Richard H. , Monson Warren G. , Lowrey Robert S.
Published: July 2010

The crude protein content and nylon bag dry matter digestibility (DMD) of autumn‐saved ‘Coastal’ bermudagrass (Cynodon dactylon (L.) Pers.) were normal grass of that age in mid‐November, but decreased rapidly thereafter. The decrease was more rapid when accumulation began later in the summer, and when weather in the autumn was warm and wet. Rate of N fertilization in the autumn did not influence DMD or protein content. Animals might be able to make small gains on the youngest grass in November, but could not maintain their weight on autumn‐saved pasture later in the winter without supplemental feeding.
Summer Fallow for Dryland Winter Wheat in the Semiarid Great Plains1
Authors: Smika D. E.
Published: July 2010

A study comparing fallow‐wheat (Triticum aestivum) with continuous wheat under semiarid conditions showed fallow‐wheat average yields to be over three times greater than average continuous wheat yields. The fallow‐wheat system provides stable production with no crop failures when compared with continuous wheat, which failed more than 30% of the time. Average water‐use efficiency for fallow‐wheat was 80% greater than that for continuous wheat when annual precipitation was between 24.6 and 43 cm. This showed that fallow‐wheat was the most efficient means of producing winter wheat when average annual precipitation was less than 43 cm. Fifty‐eight or more centimeters of annual precipitation was required before continuous wheat with N fertilizer used water as efficiently as fallow‐wheat without N. Nitrogen content of fallow‐wheat was 0.22% higher than that from continuous wheat.

Nitrogen fertilizer was necessary for maximum continuous wheat yields, water‐use efficiency and N content. But in this semiarid area, average fallow‐wheat yields without N were 2.6 times better than continuous wheat yields with N. Continuous wheat with fertilizer N used water only 71% as efficiently as fallow wheat without N fertilization. Furthermore, N content of fallow‐wheat grain without N fertilization was as high as that of continuous wheat with fertilizer N. In all aspects, the fallow winter wheat cropping system was much superior to continuous winter wheat and proved necessary for stable winter wheat production under semiarid conditions in the Great Plains.
Critical Levels of Manganese and Magnesium in Cotton at Different Stages of Growth1
Authors: Gheesling R. H. , Perkins H. F.
Published: July 2010

Cotton was grown 105 days in washed silica sand and subjected to levels of Mn and Mg above and below amounts necessary to create visual deficiency symptoms. Leaf blades were found to be the best indicator of the nutrient status of Mn and Mg. The levels below which Mn deficiency was evident in the blades were 15 ppm. Plant leaf blade tissue containing less than 2,000 ppm Mg exhibited Mg deficiency. Leaf petioles and stems were less desirable as indicators of the Mn and Mg status of cotton than leaf blades.
A Clonal Competition Experiment with Alfalfa, Medicago sativa L.1
Authors: Rumbaugh M. D.
Published: July 2010

Two levels of competition were tested with spaced plantings of 83 clones of ‘Vernal’ alfalfa. Homocompetition was defined as a propagule of a clone competing against other propagules of the same clone whereas heterocompetition was a propagule of a clone competing against propagules of any other clone randomly extracted from the same source population. Plant characteristics evaluated were dry forage weight, crown width, stem length, and stem number. No strong evidence supporting the existence of differences between the two competition levels was found. A clone ✕ competition level interaction was detected. Examination of the association between competing plants and their bordering plants suggested unequal propagule development and unknowing selection of the most vigorous and largest propagules for the center subplot positions at the time of transplanting.
Neutron Activation Analysis Technique for the Determination of Extractable Aluminum
Authors: Beyer Lawrence E. , Baker Dale E.
Published: July 2010

Activation analysis for aluminum extracted from stripmine spoils with N NH4OAc at PH 4.8 was found to be a rapid method with high sensitivity. The analysis involved 1 minute of exposure of the extract to a neutron flux of 3 ✕ 1012 cm−2 sec−1 followed by counting of the gammas of 1.78 MEV for 100 seconds.
Effects of Nitrogen and Phosphorus Fertilization on Growth, Yield, and Cooking Characteristics of Rice1
Authors: Place G. A. , Sims J. L. , Hall V. L.
Published: July 2010

One greenhouse experiment and four field experiments were conducted during 1964–65 to determine (a) the effect of rate, time, and method of P fertilization on grain yield, yield components, and cooking quality estimation of rice, and (b) the existence of N × P interactions.

Increasing P in 1964 increased lodging and reduced grain yields and 1,000 grain weight. In 1965 there was no influence of P rate. Preplant P produced darker green vegetation, broader leaves, and taller plants than did the midseason application. Differential responses disappeared by harvest time and no differences occurred except for cooking characteristics, which were more favorable with the preplant application.

Cooking characteristics were not affected by P rate, but were less favorable as N was increased in three experiments and more favorable in the other experiment. Interactions between time of P application and N rate showed cooking characteristics were more favorable as N was increased and P applied at midseason than when P was applied preplant. Interactions between P application time and P rate showed that increasing P and applying it preplant improved cooking characteristics over those of the same rates applied a midseason. The N X P interactions were inconsistent.

In the greenhouse study, soil‐incorporated P increased straw weight more than did broadcast P, but did not affect plant height, panicle number, or panicle weight. Increasing N increased panicle number, total panicle weight, straw weight and plant height. Increasing P decreased height and increased values for the other variables. The only interaction showed that increasing P and incorporating it increased panicle number and straw weight more than broadcasting it.
Persistence of Crop Seeds in Soil1
Authors: Rampton H. H. , Ching Te May
Published: July 2010

Thirteen species and varieties of crop seeds were buried in the field at 2.6‐, 5.1‐, 7.6‐, 12.7‐, and 17.8‐cm (1‐, 2‐, 3‐, 5‐, and 7‐inch) depths in Saran mesh bags to study seed persistence and depletion. Persistence and viability tended to increase with increasing burial depth, especially in ‘Dixie’ crimson and ‘Pennscott’ red clovers. Seeds of ‘Illahee’ red fescue were depleted first; none were found in the 2nd year. No viable seeds of Danish commercial orchardgrass, ‘Alta’ tall fescue, or chewings fescue were found in the 3rd year. ‘Linn’ perennial ryegrass retained a trace of vialibity into the 4th year. Oregon annual ryegrass seeds showed viability in the 7th year. Seeds of ‘Highland’ colonial bentgrass, Dixie crimson clover, and Pennscott red clover had considerable viability in the 7th year. Some changes in field history requirements for certified seed production in certain species seem to be warranted.
Oxygen Diffusion in the Soil‐Plant System II. Respiration Rate, Permeability, and Porosity of Consecutive Excised Segments of Maize and Rice Roots1
Authors: Luxmoore R. J. , Stolzy L. H. , Letey J.
Published: July 2010

Respiration rates were determined at 4.4, 20.8 and 30% oxygen concentration for consecutive excised segments of maize (Zea mays L.) and rice (Oriza sativa L.) roots. From these data, the maximum respiration rate, the oxygen concentration at which respiration was half of the maximum rate, and the root permeability to oxygen were derived for each position along the root, up to 10 cm from the root tip for maize and 6 cm for rice. The gas‐filled porosity of these segments was measured by the pycnometer method.

The root tip segment is characterized by the highest maximum respiration rate, highest permeability, and lowest porosity. Both respiration rate and permeability decrease with distance from the root tip, whereas porosity increases to a maximum of 10% for maize and 33% for rice. The oxygen concentration at which respiration is half of the maximum rate is about 8% for maize and about 16% for rice at each position along the root.
Toxicity of Preplant Anhydrous Ammonia to Germination and Early Growth of Corn: I. Field Studies1
Authors: Colliver G. W. , Welch L. F.
Published: July 2010

Field experiments were conducted to study the effects of preplant anhydrous ammonia on germination and early growth of corn (Zea mays L.). Corn was planted directly over and parallel to NH3 bands applied at different rates, depths, and times before planting. Injurious effects on corn observed with certain NH3 treatments were: reduced stand, stunted early growth, restricted seedling root development, and increased occurrence of P‐deficiency symptoms. These effects were generally most severe for NH3 applied 10 cm deep immediately before planting at 5 cm deep. Increasing the time interval to 1 or 2 weeks between application and planting generally reduced the toxic effects. Increasing the depth of application was more effective in reducing injury than was increasing the time interval between application and planting. Injury was largely prevented when application depth was 25 cm, for all times and rates of application. Injury generally increased as rate of NH3 application increased. Soil (NH3 + NH4+)‐N concentration near seeds in excess of approximately 1,000 ppm resulted in significant stand reductions.
Photosynthetic Rate of Three Soybean Communities as Related to Carbon Dioxide Levels and Solar Radiation1
Authors: Egli D. B. , Pendleton J. W. , Peters D. B.
Published: July 2010

The apparent photosynthesis (AP) rate of three varieties of soybeans (Glycine max (L.) Merrill) (‘Wayne,’ ‘Harosoy,’ and a nearly isogenic ‘Harosoy’ line with narrow leaflets) with different leaf and canopy characteristics was measured with a closed canopy system in the field for 23 days between mid‐July and mid‐August 1967 at Urbana, Ill. Solar radiation was measured with an Eppley pyrheliometer whenever AP measurements were made. The closed canopy system also provided an estimate of the transpiration rate.

Increasing the CO2 concentration from 300 to 600 ppm resulted in an average increase, across varieties, of 72% in the mean daily AP rate. Mean daily AP rate of Harosoy normal dropped 87% as the CO2 level decreased from 300 to 100 ppm. Increasing the CO2 concentration from 300 to 600 ppm resulted in a decrease in transpiration for all three varieties.

When AP rates at 300 ppm were expressed on a ground area basis, Wayne fixed 6.3% more CO2 than Harosoy narrow leaf. However, when AP was expressed on a leaf area basis, Harosoy narrow leaf fixed 45% more CO2 than Wayne and Harosoy normal fixed 13% more than Wayne.

At 300 ppm CO2 none of the varieties reached light saturation at radiation intensities commonly encountered in the field. The average efficiency of the three varieties at 300 ppm CO2 was 2.16%. Under the conditions encountered in this study, apparently both the supply of CO2 to the reaction site in the leaf and the radiant energy available to fix CO2 were limiting AP.
Evaluating Sands for Athletic Turf1
Authors: Bingaman David E. , Kohnke Helmut
Published: July 2010

Compacted sands have the advantage over soils because they do not change their structure when exposed to the impact of frequent foot traffic. This is the reason that sand can be valuable as a growth medium for althletic turf.

To evaluate sands for this purpose a number of indices have been developed for quantative assessment of their properties. These are mid‐particle diameter, gradation index, specific pore diameter, pore size index, and large pore index. These indices are based on determinations of mechanical composition, water desorption relationships, evaporation, and percolation rates. Knowledge of these parameters makes it possible to estimate the amounts of air and water in a sand at any elevation above a water table. Well graded fine to medium sand, lying on an impervious layer, serves best for this purpose. By adjusting the water level and the use of fertilizer, good growth of grass on such sands was obtained.
Effect of Time of Harvest and Nitrogen Level on Yield and Grain Breakage in Transplanted Rice1
Authors: Nangju D. , De Datta S. K.
Published: July 2010

An application of up to 120 kg/ha of nitrogen fertilizer in the dry season improved the milling quality of the chalky varieties ‘IR8,’ ‘IR5,’ and ‘Sigadis’ but not that of the nonchalky variety ‘C4‐63.’ An application of up to 60 kg/ha of nitrogen increased the protein content of brown rice of the four varieties but increased the head rice yield of only Sigadis, the most chalky of the four varieties; the head rice yield of the other three varieties remained unchanged.

Irrespective of variety and nitrogen level, the optimum time of harvest of transplanted rice for obtaining maximum grain and head rice yields and highest germination percentage was between 28 and 34 days after heading in the dry season, and between 32 and 38 days in the wet season. These heading periods correspond to moisture contents of between 22 and 19% and between 21 and 18%, respectively.

Lodging increased grain yield losses in both seasons, with the losses being greater when harvested late; therefore, lodging‐susceptible varieties should be harvested earlier than lodging‐resistant varieties. Nitrogen fertilization in the dry season delayed by 2 to 4 days the optimum time of harvest of the improved varieties IR8, IR5 and C4‐63.
Ammonium Effects on Phosphorus Absorption through pH Changes and Phosphorus Precipitation at the Soil‐Root Interface1
Authors: Miller M. H. , Mamaril C. P. , Blair G. J.
Published: July 2010

The addition of NH4+ ions to a fertilizer P band is known to increase the absorption of P. This study was conducted to further clarify the mechanisms responsible for this phenomenon.

Pellets of 33P labelled monocalcium phosphate (MCP), MCP + K2SO4 or MCP + (NH4)2SO4 were placed 1.25 cm to the side of a corn root tip growing in the soil at the surface of a box with a sloping removable front. Roots in the vicinity of the pellet, and the shoots, were harvested 15 days later.

Fertilizer P concentration in the shoots was doubled by the addition of K2SO4 and tripled by (NH4)2SO4. Autoradiographs of the area surrounding the pellets indicated an accumulation of P on the surface of roots in the MCP treatment but not in the MCP + (NH4)2SO4. Autoradiographs of root cross‐sections confirmed this observation. Electron microprobe scans of root cross‐sections indicated a precipitation of Ca and P at the soilroot interface in the MCP and MCP + K2SO4 treatments. The pH of the soil‐root interface was 0.6 units lower in the MCP + (NH4)2SO4 than in the MCP treatment. The higher ratio of H2PO4‐/HPO4= ions at the lower pH is thought to be responsible for the prevention of the precipitation and the increased absorption of P in the presence of (NH4)2SO4.
Dry Matter Accumulation and Depletion in Leaves, Stems, and Ears of Maturing Maize
Authors: Center C. F. , Jones G. D. , Carter M. T.
Published: July 2010

Several maize hybrids were grown in experiments at two locations. Dried stems, leaves, and ears were weighed separately, at each of several dates of harvest. There was no significant hybrid ✕ harvest date interaction for any plant part. In one experiment, plants were cut 1½ internodes below the ear and the lower and upper portions were weighed separately, and in addition, husks were separated from leaves. Total dry weight increased significantly from the milk (12.91 metric tons/ha) to the soft dough (18.16 metric tons/ha) stage of maturity, but there was only a small and non‐significant further increase to the mature stage (18.60 metric tons/ha). Ear weight increased significantly at each of the four successive harvest dates, increasing from 8.30 metric tons/ha at the soft dough to 10.56 metric tons/ha when mature. Leaf, husk, and stem weights each decreased significantly from the milk to the mature stage. Husks, upper leaves, and upper stalks showed the greatest decreases. The data indicate that most of the ear weight increases after the soft dough stage resulted from translocation of nutrients from other plant parts.
Influence of Drying Methods and Temperatures on in vitro Dry Matter Digestibility of Corn and Sorghum Fodder and Silage1
Authors: Schmid A. R. , Marten G. C. , Goodrich R. D.
Published: July 2010

The laboratory drying procedures of lyophilizing, or oven‐drying at 50, 65, 80 or 100 C were applied to samples of fodder and silage of corn and sorghum. The residual moisture via vacuum desiccation over P2O5 and in vitro dry matter digestibility (IVDMD) were determined. The IVDMD of both fodder and silage was highest when dried via lyophilization. Lowest IVDMD was obtained from silage oven‐dried at 100 C. Drying at 65 to 80 C (rapid drying) was found satisfactory for determination of IVDMD of fodder or silage. However, large losses of IVDMD were experienced in slow drying of fodder compared to fast drying. For biochemical determinations of silage oven‐drying would not be satisfactory. High positive correlations were obtained between IVDMD of fodder and silage. Therefore, the IVDMD of corn and sorghum fodder should be a good measure of the relative differences which one might obtain in silage. The loss of IVDMD due to the ensiling process was 11.8%.
Arsenic Residue Toxicity to Vegetable Crops Grown on Plainfield Sand1
Authors: Jacobs L. W. , Keeney D. R. , Walsh L. M.
Published: July 2010

In a field study, sodium arsenite, which is used widely in Wisconsin as a defoliant for potatoes, was applied to a Plainfield sand at rates ranging from 45 to 720 kg As/ha. The plots were planted to potatoes in 1967; peas, snap beans, and sweet corn in 1968; and to peas in 1969. Yields of potatoes were greater than check at the 45 and 90 kg As/ha rates, but decreased to 79 and 24% of check yield at the high As rates. Snap bean and sweet corn yields also decreased with increasing As, and no growth was obtained on the high As plots. The As content of above‐ground portions of potatoes varied widely, and bore no relationship to As treatment. Evidence of As contamination by windblown As‐treated soil was obtained. Arsenic was below detectable limits in edible portions of peas and sweet corn, but up to 0.5 ppm of As accumulated in potato tubers and up to 84 ppm in potato peelings. Detectable levels of As occurred in snap beans, with up to 1 ppm As accumulating in snap bean seeds and pods from the 180 kg As/ha plots. Yield decreases were related highly to total, 1 N NH4OAc extractable and Bray P‐l extractable As. The data suggest that, with the Plainfield sand, marked yield reductions of peas, snap beans, and sweet corn occur at about 10, 1, and 5 ppm of total,N NH4OAc, or Bray P‐l extractable As, respectively. The finding that yield reductions and As contamination of vegetable crops will occur indicates that use of As as a potato vine defoliant on sandy soils should be discouraged.
Germination of Cultivars of Trifolium subterraneum L.1
Authors: Young James A. , Kay Burgess L. , Evans Raymond A.
Published: July 2010

The germination of seeds of 11 cultivars of subclover (Trifolium subterraneum L.) grown in California was depressed by high temperatures, and depressed by low temperatures, or they remained dormant or non‐sensitive in relation to incubation temperatures of 0.5 to 20 C. Cultivars with a relatively non‐sensitive response to this range of temperatures were least responsive to other manipulations of the germination environment. Cultivars depressed by high or low temperatures were markedly stimulated in germination when incubated at 5, 10, or 15 C with an activated charcoal substrate, or in a CO2‐ enriched atmosphere. Germination of the cultivars ‘Mt. Barker’ and ‘Bacchus Marsh’ at low temperatures was increased when incubation was on inclined plates. These cultivars also responded to the addition of 1.0 × 10‐4 to 1.0 × 10‐2 M KNO3 solutions to the germination substrate. Pellet inoculation of seeds did not stimulate germination except with ‘Dwalganup’ at 0.5 to 10 C.
Tillage Methods for Corn‐Sod Systems in the Southern Piedmont1
Authors: Adams William E. , Pallas James E. , Dawson R. N.
Published: July 2010

Corn (Zea mays L.) was grown in Coastal bermudagrass (Cynodon dactylon (L.) Pers.) with treatments representative of conventional, mulch, strip, and no‐tillage systems, both with and without irrigation on Cecil soil. Corn was also grown in tall fescue (Festuca arundinacea L.) with treatments representative of conventional, mulch, and no‐tillage systems, also with and without irrigation. The ability to grow corn in Coastal bermudagrass and fescue sods is primarily related to the degree of competition offered by the perennial grasses, with success or failure of the corn‐sod system depending on soil water availability.

In 1961, a year of above‐average rainfall, corn grain yields without irrigation ranged from 4,077 kg/ha in the corn system treated with 4.5 kg/ha of maleic hydrazide to 6,586 kg/ha for the conventional treatment. In 1962, a year of below‐average rainfall, corn yields ranged from 314 to 3,700 kg/ha for the same two treatments.

Fescue grass was less competitive than Coastal bermudagrass; therefore, corn yields with fescue grass were generally higher than with Coastal bermudagrass.

The lister‐planter treatment as well as the 4.5‐ and 9‐kg/ha maleic hydrazide rates applied to the grasses delayed corn germination and tasseling, reduced the height of the plant, average number of ears per stalk, and ear weight.

A corn‐sod system with minimum tillage is feasible in the Southern Piedmont region; however, to be assured at good grain production, irrigation is necessary.
Palatability, Chemical Composition, and Animal Gains from Selections of Weeping Lovegrass, Eragrostis curvula (Schrad.) Nees.1
Authors: Voigt P. W. , Kneebone W. R. , McIlvain E. H. , Shoop M. C. , Webster J. E.
Published: July 2010

Significant differences in palatability were detected with Hereford steers among curvula‐type selections within Eragrostis curvula (Schrad.) Nees.

Two of the most palatable selections were lower in lignin, higher in cellulose, and lower in lignin‐cellulose ratio than two unpalatable selections. These two palatable selections were also taller, later in heading, and slightly wider in leaf than two unpalatable selections.

Over a 3‐year period, Hereford steers grazing the most palatable selection gained 13% more per head than those grazing one of the least palatable selections, and 12% more per head than those grazing common, also of low palatability.

Evaluation of palatability within the curvula‐type of E. curvula resulted in selection of a strain capable of producing higher steer gains than common.
A Temperature Model for Predicting Initial Cotton Emergence1
Authors: Wanjura D. F. , Buxton D. R. , Stapleton H. N.
Published: July 2010

An empirical temperature model for predicting initial emergence time of cotton planted at 5.1 cm is described. The model is verified by comparing predicted values with data collected in field studies. The applicability of the model is confined to field situations in which soil temperature is the primary parameter exerting a limiting influence on cotton seedling emergence.
Productivity of Crimson and Arrowleaf Clovers Grown in a Coastal Bermudagrass Sod1
Authors: Knight W. E.
Published: July 2010

A split‐plot field experiment compared annual seeding and self‐reseeding of crimson and arrowleaf clovers in a Coastal bermudagrass sod. Clover species did not differ significantly for seedling counts. Earlier growth was produced by self‐reseeding stands. However, stands from both methods of seeding were good and growth was relatively uniform in all plots. Differences in total production were not significant for method of seeding. Crimson clover averaged 33% more forage than arrowleaf. The lower yields of arrowleaf were caused by poor recovery and regrowth under drought stress.

Grass following clover produced 18% more forage than grass receiving 224 kg/ha N without clover. Total grass yields following crimson and arrowleaf clovers were not significantly different. However, the first grass harvest following arrowleaf was always reduced. This was caused by greater competition from arrowleaf clover than from the earlier maturing crimson clovers.

Total forage production was 47% higher from the sequence of clover‐Coastal bermudagrass than from grass — 224 kg/ha N — no clover. Highest total forage was produced by crimson clover‐bermudagrass. Crimson clover contributed 22% to total yield compared to 17% for arrowleaf. This study suggests the utilization of winter annual clovers to partially supply the nitrogen requirement of summer growing grasses. In addition to a reduction in the mineral nitrate requirement, other benefits would be an extended grazing season, increased total forage production, increased forage quality, and better utilization of land resources.
Effects of Row Spacing on Evapotranspiration and Yields of Corn in a Semiarid Environment1
Authors: Fairbourn Merle L. , Kemper W. D. , Gardner H. R.
Published: July 2010

A study was made in 1967 and 1968 on a Nunn clay loam soil to determine the effects of row spacing on evapotranspiration (ET) and yields of corn (Zea mays L.) in a semiarid environment. Double rows 0.3 m apart flanked on each side by spaces 1.8 m wide as used in the microwatershed system were compared with single rows in spacings of 0.9, 1.2, and 1.8 m. ET and yields of the double rows and the single rows of 0.9 and 1.2 m spacings were very similar. These results indicate an important degree of freedom is allowed in planning management systems such as microwatersheds to increase water use efficiency.
Influence of “Pop‐up” Fertilizers on Soybean Stands and Yield1
Authors: Clapp J. G. , Small H. G.
Published: July 2010

Both liquid and granular fertilizers containing nitrogen, phosphorus, and potassium were applied directly in the seed zone of soybeans (Glycine max (L.) Merrill) at planting. An application of 35.5 liters/ha (3.8 gallons/acre) of a liquid 5.0‐8.8‐4.2 (N‐P‐K) “popup” fertilizer reduced stands by 57.8% and yields by 20.3%. Plant stands were reduced when only 11.2 kg/ha (10 lb/acre) of a granular 10‐15‐5 (N‐P‐K) “popup” fertilizer was applied in the seed zone at planting.
Variation in Taproot Elongation Rate as Influenced by Composition of the Soil Air1
Authors: Huck M. G.
Published: July 2010

Elongation rates of cotton and soybean taproots were measured while the O2 content of a gas stream passing through the soil surrounding the roots was varied. Elongation rates were comparable to controls at all O2 concentrations above 10%. Elongation ceased completely within 2 to 3 min after all O2 was purged from the system with 100% N2 gas, and returned to normal shortly after 21% O2 was returned to the system, provided the period of anaerobiosis had not exceeded 30 min. Longer periods of complete anaerobiosis resulted in killing of a certain percentage of root tips until approximately 100% of the primary taproots were killed at 3 hr without O2 for cotton and 5 hr for soybeans. Oxygen levels from 2 to 5% resulted in an initial reduction in rate of taproot extension, followed by a gradual return to elongation rates comparable with controls. Although 3 to 5 hr of complete anaerobiosis evidently killed the terminal meristematic region of the taproots, new lateral growth developed from the cortex within a day or two after cessation of growth of the terminal meristems. Distribution of roots through a volume of soil may thus be influenced by oxygen availability and its distribution through time and space.
Water Use and Soil Water Depletion by Dryland Winter Wheat as Affected by Nitrogen Fertilization1
Authors: Brown Paul L.
Published: July 2010

Evapotranspiration, daily water use, and soil water depletion by Feekes scale (7) growth stages of N‐fertilized winter wheat (Triticum aestivum, L. ’Winalta’) were measured under dryland field conditions. Fall‐applied N (NH4NO3) rates were 0, 67, and 268 kg/ha (0, 60, 240 lb/a). Soil water measurements were made at weekly intervals with a neutron moisture meter. Soil NO3−N to 183 cm (6 ft) in early spring was 21 kg/ha 19 lb/a).

ET for the spring‐summer growth period was 22.1, 27.2, and 31.5 em (8.7, 10.7, and 12.4 in.) for the respective N treatments. Daily ET reached maximum values at the headed‐to‐flower stage. Soil water extraction was largely limited to the upper 91 cm (3 ft) with no N. With N, the wheat extracted water to 183 cm. Stored soil water supplied 6.1, 11.2, and 15.5 cm (2.4, 4.4, and 6.1 in.) of water to the wheat grown on the three N treatments. This was 30, 55, and 76% of the plant available water to 183 cm. At maturity, there was 18.0. 13.2, and 9.6 cm (7.1, 5.2, and 3.8 in.) of plant available water remaining in the soil to a depth of 183 cm.

Grain yields were 1,610, 3,090, and 3,630 kg/ha (24, 46, and 54 bu/a). In addition to increasing ET, N increased water use efficiency by an average of 56%.
Effects of Temperature and Flooding on Rice Growing in Saline and Alkaline Soil1
Authors: Place G. A. , Siddique M. A. , Wells B. R.
Published: July 2010

‘Bluebelle’ cultivar of Oryza sativa L. was grown in a growth chamber at 4 and 16, 10 and 21, 16 and 27, and 21 and 33C night (10 hr) and day (14 hr) temperatures, respectively. Flood water was applied 12 (early) or 24 (late) days after seedling emergence at 6‐ and 12‐cm depths to seedlings growing in saline, alkaline, and normal Crowley silt loam soil. Plant tops were harvested 53 days after seedling emergence and analyzed for dry matter production and composition of P, K, Mg, Na, Fe, Mn, and Zn. Water samples were collected at the soil‐water interface 1, 2, 5, 7, 8, 9, 10, 11, 14, and 15 days after seedling emergence and analyzed for pH, electrical conductivity, CO3‐, HCO3‐, and C1‐.

When temperature was increased, the order of dry matter production by plants growing in the various soils was normal > saline > alkaline. Applying flood water 12 days after seedling emergence caused plants growing in saline and normal soils to produce more dry matter, whereas those growing in alkaline soil produced more dry matter when flooded 24 days after seedling emergence. Varying flood depth did not affect growth.

Plants growing on saline and alkaline soils at 21 and 27C were chlorotic and P/Zn was less than 1.0. When temperature was increased to 31C chlorosis disappeared and P/Zn was greater than 1.0; however, the data did not explain the effects of flood time on growth.

Bicarbonate level of water above the alkaline soil was higher when flooding was delayed. This suggested young seedlings were more sensitive to HCO3‐ than were older seedlings, since growth was greater with delayed flooding.

Flooding saline soil early produced lower EC and Cl‐ values in the water than did late flooding. Thus, plants grew more when flooded early because salinity was lower.
Effect of Cultivation on the Nitrogen and Organic Carbon Contents of a Kansas Argiustoll (Chernozem)1
Authors: Hobbs J. A. , Thompson C. A.
Published: July 2010

As a continuation of a Kansas dryland‐soil study, started in 1916, samples from 44 plots and 2 uncultivated areas at the Ft. Hays Experiment Station were analyzed to determine the effects of a single cropping system (fallowwheat‐sorghum) from 1956(58) to 1966 on soil organic‐matter content.

Surface soils containing more than 0.100% nitrogen in l958 generally lost nitrogen between 1958 and 1966; those containing less than 0.100% generally gained nitrogen. A regression equation developed from the relationship between 1958 nitrogen content and 1958‐to‐1966 loss (or gain) predicted an equilibrium‐nitrogen content of 0.103%.

Nitrogen losses from surface soils followed a curvilinear trend, as in earlier phases of this study. Relation between soil‐nitrogen content and duration of cultivation, developed from a knowledge of nitrogen contents of unbroken sod and of cultivated plots from 1915 through 1966 predicted that, with the fallow‐wheat‐sorghum cropping system and no additional organic matter or commercial fertilizer, the soil‐nitrogen content should stabilize eventually at 0.103%.

Subsoils (18 to 51 cm) lost nitrogen between 1958 and 1966, which contrasted with results from earlier samplings.
“Runoff Farming” in the Desert. V. Persistence and Yields of Annual Range Species1
Authors: Tadmor N. H. , Shanan L. , Evenari M.
Published: July 2010

A wide variety of medics and other annual range plants were grown over a 9‐year period under waterspreading conditions in an 80 to 100‐mm winter rainfall desert. The only irrigation came from natural surface‐runoff during winter storms. Ecotypes of Medicago polymorpha, M. orbicularis, M. rotata, M. scutellata, M. truncatula, M. turbinata, and Trigonella arabica reseeded themselves each year and yielded up to 20 to 30 ton/ha fresh (4 to 6 ton/ha dry) matter. Several cultivars of forage crops and other large‐seeded crop plants, i.e. barley, oats, vetches, gave high yields but failed to perpetuate. It took legumes 3 to 4 years to become naturally inoculated. None of the clovers were established successfully under these conditions.
Corn Yields with Fall, Spring, and Sidedress Nitrogen1
Authors: Welch L. F. , Mulvaney D. L. , Oldham M. G. , Boone L. V. , Pendleton J. W.
Published: July 2010

Studies in central and northern Illinois at 4 locations and 12 location‐years were conducted with 5 rates of N applied in the fall and as spring‐preplant. Sidedress N was also included at 1 of the 4 locations for 4 years. Relative efficiency of the times of application was calculated by dividing the corn (Zea mays L.) yield increase from a given rate of N added at one time by the yield increase from the same rate of N applied at another time.

At the Carthage and Hartsburg locations the 3‐year average relative efficiencies of fall‐ versus spring‐applied N are about 0.8 and 0.9 (fall was 80 and 90% as effective as spring) at N rates of 67 and 134 kg/ha, respectively. Fall and spring N were about equally effective at 201 and 268 kg/ha of N. There was generally little yield response to N rates greater than 201 kg/ha at Carthage and Hartsburg. Fall and spring N gave similar corn yields for all rates of N at Urbana.

For the 4‐year average at DeKalb, sidedress N was the most effective, spring N was intermediate, and fall‐applied N was the least effective. The difference between spring and sidedress N was less than that between fall and spring N.

There was considerable year‐to‐year variation in relative efficiency. The importance of the time at which conditions suitable for N loss occur is discussed.
Nitrogen Fertilization of Semiarid Grasslands: Plant Growth and Soil Mineral N Levels1
Authors: Power J. F. , Alessi J.
Published: July 2010

To evaluate the fate of mineral N in a grassland ecosystem, fertilizer N was applied to native grassland in North Dakota at rates up to 540 kg N/ha either (a) all in 1 year, (b) one‐third in each of 3 years, or (c) one‐sixth each of 6 years. Cumulative production of grass tops for the 6 years increased with increased amounts of total N applied, but was not affected by timing of fertilizer application. With continued annual fertilization, responses were measureda at progressively lower rates. At 270‐kg N or more, residual effects were still significant 6 years later. Dry weights of three oats crops grown on these soils in the growth chamber indicated that greater N availability in fertilized soils contributed appreciably to these residual effects. Soil NH4+‐ and NO3‐‐N levels for many treatments exhibiting residual effects were no higher than for unfertilized plots, indicating residual N was present in other than mineral forms. Fertilizer N is probably immobilized by all components of the soil‐grass ecosystem (especially grass roots) and the mineralization of this immobilized N may contribute to residual effects. Fertilizer N applied in excess of the immobilizing capacity of the ecosystem remains in mineral form until required by the grass. Consequently, the presence of a mineral N pool indicates that N has been eliminated as a growthlimiting factor and maximum production from the available water is being achieved.
Root Development and Rooting Patterns of Soybean (Glycine max (L.) Merrill) Evaluated Under Field Conditions1
Authors: Mitchell R. L. , Russell W. J.
Published: July 2010

The soybean (Glycine max L.) root system, by 21 days after planting, consisted primarily of secondary lateral roots that had developed from an enlarged upper 10‐ to 15‐cm segment of the “taproot.” Four longitudinal rows of lateral roots spaced at 90 degree intervals around the taproot developed acropetally. These laterals grew horizontally for 40 to 50 days and, after reaching 35 to 40 cm in length, turned downward, providing extensive deep penetration of the soil profile.

Root growth and development occurred in three phases, each phase corresponding to specific vegetative or reproductive stages. The completion of each phase of development represented further penetration of the soil profile and proliferation by the root system.

Root dry weight was concentrated in the upper portion of the soil profile, 90% or more in the upper 7.5 cm early in the season and in the upper 15 cm during the remainder of the season.

Differences were observed among the eight varieties sampled for rate of root developmnt, total root dryweight accumulated, and type of rooting pattern.
A Self‐Watering System for Growing Plants in Potted Soils1
Authors: Dolar S. G. , Keeney D. R.
Published: July 2010

A wick culture technique for growing plants in potted soils was developed. In the method described, about 50 oat (Avena sativa L.) seeds are sown to a pot and are grown under plant‐growth room conditions for about 4 weeks. Water for the plants is supplied entirely by a fiberglass wick extending from the center of the pot into a glass cylinder. The technique is especially adaptable to micronutrient element studies. It has several advantages over the ordinary pot culture techniques for growing plants. The construction materials are available and inexpensive.
Moisture Requirements for Seed Germination of Peanuts1
Authors: Mixon Aubrey C.
Published: July 2010

Peanut seed (Arachis hypogaea L. var. ‘Early Runner’) were removed from moist germination pads, covered with germination blotters in a 25 C germinator at 30‐ to 45‐min intervals and placed in sealed petri plates to allow seed germination (radicle emergence). Seed moisture at time of placing in sealed container revealed that average seed moisture of about 35% was necessary for any seed to germinate. Radicle emergence of all seed in a sample was obtained at about 55 to 60% average seed moisture.
Competition between Grass and Legume Species on Dryland1
Authors: Dubbs Arthur L.
Published: July 2010

Two legumes and four grasses were grown in various combinations on dryland to determine the degree of competition one species exerted upon another. Species competition was measured by stand percentage, forage yields, plant height, and percent crude protein. Russian wildrye (Elymus junceus Fisch.) was the most competitive species and sainfoin (Onobrychis viciaefolia Scop.) the least under conditions experienced at this location during the trial period. Sainfoin was the only species showing a significant loss of stand during the 5‐year period. The stand loss resulted from a combination of winterkilling and species competition. Grasses yielded more when competing with legumes than when competing with each other. Competition between grasses was nearly equal and no combination excelled another. Russian wildrye and alfalfa (Medicago sativa L.) were the most competitive species with sainfoin. Alfalfa plants received more competition from other alfalfa plants than from plants of other species. In general, all species were quite competitive to themselves in pure stands. Percentage crude protein of crested wheatgrass (Agropyron desertorum (Fisch.) Schutl.) increased when it was grown with alfalfa. The protein content of sainfoin was not affected by competition from any of the species. Alfalfa and Russian wildrye decreased in crude protein content when competing with smooth bromegrass (Bromus inermis Leyss.).