bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmental Influences on the Leaf Temperatures of Two Soybean Varieties Grown under Controlled Irrigation1
Authors: Carlson Richard E. , Yarger Douglas N. , Shaw Robert H.
Published: July 2010

Remote sensing techniques have been suggested as a possible tool to the agricultural research worker. In addition, plant leaf temperatures (a quantity capable of being measured by remote sensors) give an indication of the plant's response to the environment. For these reasons, an experiment was conducted in the field to investigate the relations between plant leaf temperatures and soil moisture stress and various environmental parameters.

Leaf temperatures (TL) of two soybean [Glycine max (L.) Merr.] varieties grown under controlled irrigation were measured with an infrared thermometer during a 9‐day experiment. On a given day relative leaf water content (RWC) and TL were highly correlated. When TL's were examined over different days, vapor pressure deficit (VPD) and air temperature (TA) were found to affect TL· TL increased with decreasing values of both RWC and VPD. Interactions involving both VPD and TA with RWC were observed. TL increased with increasing TA; however, the amount of increase of TL seemed related to the leaf's level of RWC. This was related to increased transpirational cooling (stomatal conductivity) at higher levels of TA. The two varieties in this experiment were significantly different with respect to TL, but the degree of significance was related to VPD.
No‐Till Corn in Fescuegrass1
Authors: Carreker John R. , Box James E. , Dawson Royal N. , Beaty E. R. , Morris H. D.
Published: July 2010

The rolling soils of the Southern Piedmont are highly erosive when clean tilled. The area is well adapted to close‐growing forage crops, but the thriving poultry industry in this region needs more grains. By combining no‐till corn (Zea mays L.) production on fescuegrass (Festuca elatior, var. arrundinacea) sod with irrigation and adequate fertilization, a number of problems might be solved.

Corn was grown on Cecil sandy loam following corn and in live fescuegrass with and without irrigation in 1969, and by no‐till planting in live, stunted, and killed fescuegrass with and without irrigation in 1970. Nitrogen rates applied to the corn were 148 kg/ha in 1969 and 112, 224, and 448 kg/ha in 1970.

Without irrigation, the corn and the live grass exhausted all available soil water during droughts in June, and the corn died. Corn growth in the stunted and killed sods was reduced, but the plants lived. With irrigation the corn and live grass used soil water faster than corn in dead sod until the corn developed a complete canopy. After the canopy developed, corn in killed sod used more soil water than did the corn in live sod. Without irrigation, corn yields were O with live sod and about 1000 kg/ha on killed sod and showed no response to N levels of 112, 224, and 448 kg/ha. With irrigation, yields were directly proportional to N levels and to the amount of live sod; yields ranged from 140 kg/ha with 112 kg/ha N on live sod to 9,980 kg/ha with 448 kg/ha N on killed sod. The excellent yields from corn in grass sod show that corn can be grown on the sloping fields of the Piedmont and related areas to fill the grain needs there without causing serious soil erosion.
Role of Pensacola Bahiagrass Stolon‐Root System in Fertilizer Nitrogen Utilization on Leon Fine Sand1
Authors: Blue W. G.
Published: July 2010

An experiment was conducted with Pensacola bahiagrass (Paspalum notatum Flugge) on Leon fine sand near Gainesville, Fla. for 6 years to determine residual effects of applied N on forage N uptake, and changes in stolons, roots, and soil N. Nitrogen was applied at 0, 112, 224, and 448 kg/ha/year. Except for the control, paired plots were used at each N rate. Nitrogen fertilization was dis. continued on one of each treatment pairs in 1969 and 1970 to determine the residual effect of N. These treatments were resumed in I971. The residual effect of N was small for all treatments, amounting to 8, 41, and 95 kg/ha total N in harvested forage above the control for the 2‐year period for the 112, 224, and 448 kg N rates, respectively. Unrecovered N through 1968 was approximately 200, 350, and 770 kg/ha for the three treatments, respectively. Nitrogen lost from the stolon root systems during 1969 and 1970 through decrease in mass and N concentrations was 60, 100, and 190 kg/ha for the three N treatments, respectively. Little of the unrecovered N could be accounted for by analysis of the surface soil. Lack of residual effect on plant growth confirmed that little available N was in the soil profile to rooting depth. Based on previous studies, leaching appears to have limited importance when N is applied to well‐established perennial grass pastures during the growing season. Conditions imposed in this soil by high water table, large amounts of plant residues, and rapid decomposition during the summer season could make denitrification a significant factor.
Increase in Conductivity of Irrigation Water during Sprinkling1
Authors: Robinson Frank E.
Published: July 2010

The test was conducted on a high evaporative demand July day to evaluate the possible harm that could result from concentration of salinity as water is sprinkled in an arid desert area.

Catchment beakers (250 ml) were set at 19‐m intervals across a 190‐ × 219‐m alfalfa (Medicago sativa L.) field that was sprinkled for 19.5 hours. Conductivity of the sprinkler water increased 21% on the field edge and 4.4% inside the field.
Water‐Use Efficiency and Its Relation to Crop Canopy Area, Stomatal Regulation, and Root Distribution1
Authors: Teare I. D. , Kanemasu E. T. , Powers W. L. , Jacobs H. S.
Published: July 2010

The differences in water‐use efficiency between sorghum [Sorghum bicolor (L.) Moench] and soybean [Glycine max (L.) Merrill] were compared in terms of leaf area index (LAI), size of root system, canopy stomatal resistance (R̄c), net assimilation rate (NAR), and evapotranspiration (ET). The field water budget was measured by recording the rainfall, and irrigation water applied in relation to the ET as measured with two weighing lysimeters.

The evapotranspiration rates of the two crops began to diverge about August 15. This was the period when the soybean canopy began to close and the soybean LAI increased to about 1.5 times that of sorghum. NAR for sorghum during stalk elongation and heading (Aug. 15) was nearly four times that of soybeans during that time.

Divergence of the two evapotranspiration curves coincided with observed differences in canopy stomatal resistance. In August after a stress period, the R̄c for sorghum at 1 and 3 pm was nearly three times the R̄c for soybeans. The increase in R̄c for sorghum was concommitant with an air temperature increase of 3 C above the air temperature near soybeans.

Sorghum had approximately twice the weight of roots per volume of soil as soybeans. Even though atmospheric demand for H2O was similar for the two crops, sorghum was able to close its stomata more than soybeans, and thus conserve soil water even with a larger root system and more water in the soil profile resulting from reduced evapotranspiration.

Water‐use efficiency of sorghum (gm DM/kg H2O) was approximately three times that of soybeans on dry matter or grain yield bases.
Ionic Balance for Barley as Influenced by P Fertility, Water, and Soil Temperature1
Authors: Follett Ronald F. , Reichman George A.
Published: July 2010

The relationship between organic anion concentration and yield of spring barley (Hordeum vulgate L., var. ‘Sacramento’) was investigated in a growth room at three levels of P. This relationship was tested at three levels of available soil water (W) and three soil temperatures (T). The concentration of organic anions was determined as the difference between the sum of the meq/kg of inorganic cations (Na+, K+, Ca2+, Mg2+) and the sum of the meq/kg of inorganic anions (CI‐, NO3−, H2PO4−, and SO42−). A normal organic anion (C‐A) concentration was considered to be that giving optimal growth. In this study, P was more important for obtaining a normal (CA) than either W or T. Phosphorus increased yields, decreased (C‐A) to near normal, and decreased the adverse effects of low W and low T. The large differences in (C‐A) between treatments suggests that, under adverse conditions, organic anions may serve as reservoirs of useful metabolites. Nitrate in the total plant tops, expressed as a percent of the total‐N (N/T), was associated with 82% of the yield variance for treatments yielding less than 11 g/can. For treatments yielding more than 11 g/can, the average value for (N/T) was 0.88%. Potassium accounted for over 55% of the inorganic cation charge and appeared to be the major form for both organic and inorganic salts. Changes in soil pH resulted from nutrient uptake, with 61% of the variance of the change in [H+] associated with the difference between inorganic anion uptake and inorganic cation uptake.
Zinc Response of Maize (Zea mays L.) Grown on Sandy Inceptisols in Western Nigeria1
Authors: Osiname O. A. , Kang B. T. , Schulte E. E. , Corey R. B.
Published: July 2010

Field experiments were conducted with IITA maize (Zea mays L.) composite B at six locations ranging from forest to savannah in the Western State of Nigeria to assess the level of zinc response on sandy Inceptisols. Zinc, as Na2 Zn EDTA, was applied as broadcast application at 0, 1.0, 2.0, 4.0, and 8.0 kg/ha. Zinc response in terms of growth development and grain yield was limited to the savannah where yield increases of 1,747 kg/ha of grain were obtained with application of Zn at 1 to 2 kg/ha.

For optimum grain yield, 12 ppm Zn in tissue appeared minimal. Maize response to Zn application was most probable when the 0.1N HCl soil‐extractable Zn was less than 1.0 ppm when measured at silking time.
Increased Yield and Persistence of Red Clover after a Soil Drench Application of Benomyl1
Authors: Leath K. T. , Zeiders K. E. , Byers R. A.
Published: July 2010

Benomyl (methyl 1‐[butylcarbamoyl]‐2‐benzimidazolecarbamate) fungicide was applied as a soil drench to red clover (Trifolium pratense L.) field plots in June 1970, the second growing season. Forage yields from the benomyl‐treatcd plots were significantly higher than yields from the untreated plots in 1970 and 1971. In September 1971, benomyl‐treated plots had more plants, many of which were large and were classified as original plants; more root borers (Hylastinus obscurus [Marsham] per plant; and fewer weeds than did the untreated plots. Fusarium was the only pathogenic fungus consistently isolated from rotted roots in September 1971.
Weanling Meadow Vole Responses to Crownvetch Forage1
Authors: Shenk J. S. , Risius M. L. , Barnes R. F.
Published: July 2010

Crownvetch (Coronilla varia L.) has been reported to contain antiquality constituents. Feeding trials were conducted to determine the feasibility of using the weanling meadow vole (Microtus pennsylvanicus) as a bioassay to assess the effects of these antiquality constituents on feed intake, body‐weight change, and ration digestibility. The feeding value of crownvetch forage was compared with that of alfalfa (Medicago sativa L.), birdsfoot trefoil (Lotus corniculatus L.), and sainfoin (Onobrychis viciaefolia Scop.) incorporated at 15% dry weight into a nutritionally adequate and balanced diet. Voles had lower intake and lost weight when fed crownvetch than when fed the other legume forages. No relationship existed between intake or weight loss and apparent digestibility. However, not all crownvetch forages resulted in lower intake and weight loss, and samples differed in their capacity to cause adverse vole responses from year to year. Voles also differed in their responses to forage fed from individual plants of the ‘Chemung’ cultivar. Low intake appeared to be the primary reason for the weight loss and death which occurred on many samples. The information presented indicates the presence of an antiquality constituent(s) in crownvetch forage that should be thoroughly investigated for its effects upon other animal species, especially rapidly growing monogastrics.
Variability of Fraction 1 Protein and Heritability Estimates for Fraction 1 Protein and Total Phenolic Constituents in Alfalfa1
Authors: Miltimore J. E. , McArthur J. M. , Goplen B. P. , Majak W. , Howarth R. E.
Published: July 2010

The primary cause of lethal alfalfa pasture bloat is Fraction 1 Protein (FR1P) and bloat occurs when FR1P is above 1.8%. Before starting a selection or breeding program to develop a nonbloating alfalfa (Medicago sp.), it would be important to know the heritability and the range of FR1P levels in alfalfa plants. Accordingly, this investigation was undertaken with the objectives of determining the distribution of FR1P levels and the heritability of FR1P and total phenolic constituents in alfalfa clones. Sampling was undertaken at the prebud to bud stage of maturity. The top 15 cm of the plants were harvested.

Fraction 1 Protein levels were obtained for 1,372 alfalfa plants of diverse origin. Only four plants, 0.3%, were below the bloat threshold of 1.8% in FR1P concentration on an oven dry weight basis. The average concentration for all alfalfa plants was 4.3%. M. sativa was generally higher in FR1P than other Medicago species. The lowest mean FR1P concentration, 3.1%, was found in M. hemicycla and M. glutinosa.

A broad sense heritability estimate for FR1P was determined from a replicated nursery of 60 clones. With single plants from four replications in the first year, the heritability of FR1P was 28%. Heritability of total phenolic constituents in the first year using data from four replications was 16%. The correlation coefficient between years for FR1P was r = 0.40, 58 df. Cultivar differences in FR1P, observed in the first year, disappeared the second year when soil fertility level was increased. The mean FR1P level in the second year was 4.8%.
Estimation of Leaf Area in Grain Sorghum from Single Leaf Measurements1
Authors: Krishnamurthy K. , Jagannath M. K. , Rajashekara B. G. , Raghunatha G.
Published: July 2010

Studies were made to examine the applicability of a common leaf product constant (K‐constant × length × width), for estimating the area of single leaf and it was found that the same constant was applicable for the 3 sorghum genotypes (Sorghum bicolor L Moench) studied (K=0.71). Adaptability of the common leaf product constant for individual leaves according to its position in the plant was also tested by regression analysis, and the same constant was found to be applicable in most cases.

Because complete measurement of all leaves of a plant in field trials is time‐consuming and involves prohibitive labor input, the most representative leaf was identified through correlation studies to use it in working out the leaf area index. The largest leaf was found to be the most representative. This representative leaf differed with genotype, depending upon total leaf number. An appropriate factor to work out leaf area of the whole plant from a single leaf was determined. This leaf area factor was found to vary from 4.106 to 5.873 among the sorghum genotypes.
Phosphate Uptake Rate of Corn Roots as Related to the Proportion of the Roots Exposed to Phosphate1
Authors: Jungk A. , Barber S. A.
Published: July 2010

Little information is available on the effect of reducing the proportion of a plants roots in contact with P on the rate of P uptake by those roots. Three experiments were conducted with corn (Zea mays L.) in solution culture in a growth chamber. In the first experiment trimming roots to reduce root length per plant gave results on P uptake similar to using a split‐root system where a portion of the roots were in a nutrient solution containing 50 μM P. Uptake of P over an 8‐hour or shorter period was in proportion to the length of root exposed to the P solution. Hence, phosphorus uptake rate per unit of root was not increased by reducing the proportion of the root in contact with P. In an experiment conducted over a 4‐day period, with P levels of 100 and 1000 μM, an increase of 20 to 40% P uptake per unit of root occurred when root length was reduced to 37 to 58% by trimming. A lower P level in the plants with trimmed roots as compared to those with untrimmed roots may have caused the increase in P uptake rate per meter of root. In a 4‐hour experiment with P concentrations between 5 and 10 μM, trimming the roots did not increase the P uptake rate per unit of root length. The results indicate that it is necessary to supply P to a large proportion of the roots in order to adequately supply the plant.
Relation of Foliar Disease of Quality of Alfalfa Forage1
Authors: Leath K. T. , Shenk J. S. , Barnes R. F.
Published: July 2010

A method is needed to detect the effects of foliar diseases on forages in order to determine whether the feeding of diseased forages to animals is potentially dangerous. To obviate some of the difficulties of largeanimal feeding trials, we used the meadow vole (Microtus pennsylvanicus) to assay for anti‐quality components in diseased alfalfa (Medicago sativa L.) produced in the greenhouse. The forage was inoculated sequentially with each of five foliar pathogens and compared with healthy forage for chemical composition, in vitro dry matter disappearance (IVDMD), and weanling meadow vole responses. Foliar disease did not significantly alter chemical composition, IVDMD of the forage, or dry matter digested by weanling voles fed these forages at 60% of their diet. Intake of alfalfa diseased with Uromyces striatus Schroet. was significantly greater than that of the healthy forage and intake of alfalfa diseased with Stemphylium botryosum Wllr. was significantly lower. Weight gains were significantly lower for voles fed alfalfa diseased with Phoma medicaginis Malbr. and Roum. and S. botryosum. Neither intake nor weight gain was affected by forage diseased with Leptosphaerulina briosiana (Poll.) Graham and Luttrell or Pseudopeziza medicaginis (Lib.) Sacc.
Stand Establishment of Bermudagrass from Seed1
Authors: Ahring R. M. , Huffine W. W. , Taliaferro C. M. , Morrison R. D.
Published: July 2010

Common bermudagrass [Cynodon dactylon (L.) Pers.] when established with commercial seed in the northern part of the bermudagrass belt, has a high percentage of winter‐kill. The feasibility of developing seeded bermudagrass cultivars with greater cold tolerance is currently being investigated in Oklahoma. The objective of this research was to compare the winterhardiness of seeded common bermudagrass to an open‐pollinated, seed‐producing, experimental clone (‘A‐9945’).

Seedling differences were studied between and within the two strains established at 2‐week intervals beginning in April and ending in August. Fall measurements were taken of forage dry matter production and fibrous root and rhizome volumes. The following January and February, rhizomes and crown‐buds were harvested from each establishment date and their viability determined. These measurements were then related to recovery and growth (e.g., early spring shoot emergence and density) that spring. Fibrous roots and rhizome volumes were determined by submerging samples in graduated cylinders containing known volumes of water. Dry weights were measured using standard oven‐drying procedures.

Comparison of winter hardiness between strains demonstrated that A‐9945 initiated rhizome production earlier and in greater quantities than “common.” Plants of A‐9945 emerged 3 to 4 weeks earlier than common in the spring; a greater number from the July planting dates recovered the following spring. Winter survival of common depended almost entirely on crown‐bud hardiness. Rhizomes and crown‐buds contributed to the survival of A‐9945. Planting after July 21 for A‐9945 and May 25 for common did not permit sufficient time for development of rhizomes and crown‐buds capable of complete winter survival.
Soil Fertility and Crop Responses at Selected Landscape Positions1
Authors: Malo D. D. , Worcester B. K.
Published: July 2010

A large part of the glacial drift plain of North Dakota is composed of sloping surfaces which are the result of late Wisconsin glaciation and post glacial erosion and sedimentation. The geologic processes of erosion and sedimentation affect soils, their properties, and crop response at various landscape positions. There is limited research data on the effect of landscape position on soil fertility levels and crop production. Knowledge of these relationships on a hillslope can aid in understanding crop growth at various landscape positions. The objectives of this research were to gain an understanding and insight into the occurrence and distribution of soils and their properties as they exist on the landscape in relation to crop responses.

Soil properties measured with respect to landscape position were soluble salt content, inorganic C content, water table levels, and soil test levels of N, P, and K. The crop responses measured were emergence plant counts, plant height, maturity, and crop yield.

Soil NO3‐N and extractable P levels were minimal at the shoulder position, where erosion activity was greatest and maximal at the toeslope where sedimentation and higher soil moisture contents were found. Minimum exchangeable K levels were found at the salt rim where electrical conductivity values were high.

Initial plant populations were lowest at the salt rim located at the footslope position. Plant height was greatest at the backslope and least at the footslope. Lowest yields and highest grain moisture contents were found at the lowest landscape positions. Highest yields occurred at the backslope while lowest grain moisture contents were found at the shoulder position.

Results of this study show that differences in plant responses to landscape position exist primarily because of changes in soils and their associated properties. Landscape position is helpful in identifying soil types which can aid in fertilizer management decisions.
Stalk Rot Incidence and Yield of Corn as Affected by Inhibiting Nitrification of Fall‐applied Ammonium1
Authors: Warren H. L. , Huber D. M. , Nelson D. W. , Mann O. W.
Published: July 2010

Large overwinter losses of fall‐applied fertilizer N from midwestern U.S. soils occur through leaching and denitrification. These losses result in decreased efficiency in the utilization of applied N and often in lower crop yields. Of the various management techniques available to reduce N losses, previous studies with spring‐applied N suggested that inhibiting nitrification of applied ammonium with specific chemicals appears to be most compatible with current fertilization and crop production practices. We tested the effectiveness of a specific nitrification inhibitor, 2‐chloro‐6‐(trichloromethyl)pyridine (nitrapyrin), in reducing losses of fall‐applied N by comparing the growth, disease incidence, and yield of corn growing in field plots receiving anhydrous ammonia with those treated with anhydrous ammonia containing the inhibitor.

Three field experiments on two soil types (Typic Argivdoll coarse‐loamy, mixed mesic and Vertic Halpla‐quoll fine, montmorillonitic, mesic) demonstrated that inhibition of nitrification of fall‐applied ammonium markedly increased grain yields and grain protein and decreased the incidence of stalk rot in corn. Corn yields were increased as much as 207% (average increase was 68%) as a result of applying 0.55 kg of nitrapyrin/ha with fall‐applied anhydrous ammonia when compared to yields obtained with anhydrous ammonia without the nitrification inhibitor. In all experiments, stalk rot incidence in corn was reduced as a result of inhibition of nitrification — the reductions varied from 60 to 96%. In two experiments, grain protein content was increased by 7 to 38% as a result of application of nitrapyrin with fall‐applied N.

The results of this study indicate that severe losses of N may occur as a result of fall application of N fertilizers and that these losses may be markedly reduced by using a nitrification inhibitor to minimize the formation of nitrate. The increased yield and grain protein obtained from nitrapyrin addition likely resulted from greater availability of N in nitrapyrin‐treated plots. The reduction in stalk rot may have resulted from altered N metabolism in plants growing in nitrapyrin‐treated plots because of the uptake of substantial amounts of ammonium. This was indicated since stalk rot was reduced by nitrapyrin in plots which were not under N stress. Another explanation for reduced stalk rot may reside in the fact that nitrapyrin‐treated plots had more vigorous plants than plots not receiving the nitrification inhibitor. The data also suggest that N application rates used for corn production may be decreased with no loss in yield if a nitrification inhibitor is used to minimize losses of applied N.
Broadleaf Weed Control in Dormant Bermudagrass Turf1
Authors: Johnson B. J.
Published: July 2010

Broadleaf weeds continue to be a major problem in turfgrass during mild winters throughout the Southeast. Therefore, experiments were conducted with herbicides applied postemergence to determine the maximum weed control with the least amount of chemical treatment. Two new herbicides alone with presently available chemicals were applied to dormant bermudagrass [Cynodon dactylon L. Pers.] in singly and repeatedly at 1 and 2✕ rates at three locations. Soil types were Cecil sl (Typic Hapludult), Durham scl (Typic Haludult), Gwinnett scl (Typic Rhodudult), and Pacolet‐Wickham sl (Typic Hapludult). Parsley‐piert (Alchemilla microcorpa Boissier Reuter) was completely controlled with single treatments of methazole [2‐(3,4‐dichlorophenyl)‐4‐methyl‐1,2,4‐oxadiazolidine‐3,5‐dione] and cisanilide (cis‐2,5‐dimethyl‐N‐phenyl‐1‐pyrrolidinecarboxamide) while two applications were required to obtain satisfactory control with silvex [2‐(2,4,5‐trichlorophenoxy)propionic acid], paraquat (1,1'‐dimethyl‐4,4'‐bipyridinium ion), dicamba (3,6‐dichloro‐o‐anisic acid), and combination treatments of 2,4‐D [(2,4‐dichlorophenoxy)acetic acid] with either dicamba, silvex + dicamba, or mecoprop {2[(4‐chloro‐otolyl)oxy]propionic acid} + dicamba. Paraquat resulted in excellent corn speedwell (Veronica arvensis L.) control with a single treatment, but two applications were required for similar control with cisanilde or methazole. Two applications were generally required of 2,4‐D, silvex, dicamba and the two and three combination treatments for satisfactory corn speedwell control, especially in plots treated with 1✕ rates. All the herbicides gave good to excellent henbit (Lamium amplexicaule L.) and common chickweed [Stellaria media (L.) Cyrillo] control except for 2,4‐D when applied to henbit at the 1✕ rate.
Corn Yield and Nutrient Uptake as Affected by Water‐Table Depth and Soil Submergence1
Authors: Chaudhary T. N. , Bhatnagar V. K. , Prihar S. S.
Published: July 2010

Crops are affected by fluctuations in the water table by seasonal rainfall and soil submergence during growth. A better understanding of their response will help us to optimize drainage and irrigation. Response of irrigated corn to (i) four static water‐table depths (60, 90, 120, and 150 cm) as affected by the growing‐season rainfall and (ii) single or repeated submergence for 1 to 6 days was studied in 58 cm diam by 183‐cm long metal barrels using silt loam soil during 1971 and 1972.

Crop response to water‐table depths varied with rainfall during growth. In a wet year, water table at the 120 cm depth gave the highest and that at the 60 cm depth the lowest yield. In a relatively dry year, yield was highest with water tables at 60 and 90 cm depths and decreased with deeper water tables.” It is indicated that a water table at 120 cm depth is desirable for corn. A multiple regression equation indicated that soil water depletion from the upper 30 cm before irrigation, ground water contribution, and oxygen diffusion rate at 15 cm depth accounted for 79% of the variation in yields across water tables. In both years, N, P, and K concentrations in grain and stover were not significantly affected by water table treatments.

Grain yields were reduced significantly by submergence exceeding 1 day. For comparable durations, yield reductions were smaller for single than repeated submergence. Submergence during early growth was more harmful than during late growth. Prolonged soil submergence significantly reduced N, P, and K concentrations in the grain. For optimum corn production it is necessary to drain excess water from the root zone within 1 day of soil submergence.
Phosphorus Uptake by Soybeans as Influenced by Moisture Stress in the Fertilized Zone1
Authors: Marais J. N. , Wiersma D.
Published: July 2010

Reports on the effect of soil moisture stress on plant uptake of P have been conflicting. The effect of the dynamic variation in soil moisture on P uptake by soybeans (Glyfine max L. Merr.) was studied in vivo. A split‐root technique with plants grown in 3 liter containers in the greenhouse was used whereby moisture stress was localized in the zone having the only source of P for the roots, while water and P‐free nutrients were supplied through the other portion of the root system. The procedure minimized the effect of plant‐water deficit.

Differences between moisture treatments accounted for 81.5% of plant P content when the effects of fertilizer treatments were removed, while variation in soil moisture content within each moisture treatment accounted for only 8%. The extent P uptake was impaired by high moisture stress was conditioned by the P status of the plant which in turn was determined by the previous soil moisture history of the zone supplying the P. After watering, plants exposed to a high moisture stress resumed P uptake at a rate exceeding that of plants absorbing P from the adequately watered compartment.

The range of response to which increasing levels of fertilizer P was obtained increased as the period of moisture stress in the fertilized zone was prolonged. Temporary luxury consumption of P, induced by high levels of soil P and foliar application, benefited soybeans whose P supply was curtailed by high moisture stress.

Moisture stress appeared to affect P uptake largely through its influence on diffusion rather than mass‐flow. It is suggested that the inconsistencies of field results reported in the literature studying the relationship of P uptake and moisture stress could be caused by the peculiar P uptake behavior found in these experiments.
Potential Tetany Hazard of N‐Fertilized Bromegrass as Indicated by Chemical Composition1
Authors: Follet R. F. , Power J. F. , Grunes D. L. , Hewes D. A. , Mayland H. F.
Published: July 2010

The objective of this field experiment was to determine the effect of N fertilization on yield and chemical composition of smooth bromegrass (Bromus inermis L.) and the potential for grass tetany hazard in the northern Great Plains as indicated by chemical composition of bromegrass forage. Chemical components of forage considered in relation to the hazard of tetany (a metabolic disorder of ruminants resulting from forage with low Mg availability) were inorganic cations, organic anions, aconitate, and % total N/% total water‐soluble carbohydrate ratio (N/TWSC). Soil was Parshall fine sandy loam, pachic haploborall. Yields and chemical composition of oven dried forage from plots not previously harvested were determined at approximately 3‐week intervals beginning May 9. Differences between the sum (in meq/kg) of inorganic cations (Na+, K+, Ca2+, Mg2+) and inorganic anions (C1‐, No3‐, H2PO4‐, SO42‐) in forage was defined as the concentration of organic anions (C‐A).

Mature forage yield obtained from the unfertilized check plot treatment on July 29 was only 29 and 22% of yields obtained from plot treatments fertilized with 90 and 270 kg N/ha, respectively. The K/(Ca+Mg) ratios and K concentrations increased during May and early June, resulting in a K/(Ca+Mg) ratio near or above 2.2 during June and early June in oven dried forage from fertilized treatments. Potassium, expressed as a fraction K/C of the total cations (C), accounted for 35 to 74% of the cationic charge. Fertilization with N increased total N and K concentration and K/C in the forage. As K/C increased, Mg/C and Ca/C decreased and K/(Ca+Mg) increased. Aconitate and C‐A concentration correlated highly with K concentration and were increased by N fertilization. Aconitate levels exceeded 1% on May 28; the 270 kg N‐treatment remained above 1% through July. Nitrogen fertilizer increased N/TWSC in spring‐harvested forage, compared to unfertilized forage, and greatly accentuated the peak N/TWSC values occurring in late spring samples.

This study indicated that although potential for increased forage and livestock‐carrying capacity with N fertilization is tremendous, N‐fertilization may result in a potential tetany hazard to ruminants. Therefore, management practices are needed which minimize tetany hazard while bromegrass yields are increased by N fertilization.
Effects of K Fertilization on Freezing Tolerance and Carbohydrate Content of Festuca arundinacea Schreb. Maintained as Turf1
Authors: Cook Thomas W. , Duff D. Thomas
Published: July 2010

The purpose was to determine the effects of K fertilization on freezing tolerance and carbohydrate content of Festuca arundinacea Schreb. ‘Kentucky 31’ which was reputed to be susceptible to cold injury in northern areas of the U.S. From September through mid‐November, K from KCl was applied to field plots of Bridgehampton silt loam soil in increments to achieve levels of 0, 10, 20 or 40 kg/ha. The same plots received a total of 20 kg N/ha as NH4NO3 in four splits ending in mid‐October. Sand cultures were fertilized three times/week with solutions containing 200 ppm N, 64 ppm P, and 0, 50, or 200 ppm K. Other essential elements were applied in standard amounts and Na was excluded.

Samples from both areas were analyzed from October 1973 through April 1974. Tissue K was determined by flame photometry and freezing tolerance by percentage of total electrolytes lost from crown tissue after freezing. Water and 85% ethanol soluble carbohydrates were determined by anthrone and polymeric carbohydrates by the difference between water and ethanol soluble values.

Though exchangeable soil K measured low in field plots originally, available K was adequate for development of freezing tolerance and accumulation of carbohydrates since neither was influenced by K fertilization. In sand culture tissue no effects on either freezing tolerance or carbohydrate content were observed even though K contents ranged from 0.7% to over 3% of dry weight during the cold hardening period. Results suggest fall fertilization with K is not critical to development of freezing tolerance or accumulation of carbohydrates under Rhode Island conditions.
Double Cropping for Hay and No‐tillage Corn Production as Affected by Sod Species with Rates of Atrazine and Nitrogen1
Authors: Bennett O. L. , Mathias E. L. , Sperow Charles B.
Published: July 2010

Studies comparing conventional tillage with no‐tillage practices for corn (Zea mays L.) planted in one or two sod species have been conducted at several locations. Studies comparing growth of corn, when planted in several sod species at variable rates of N, have not been determined. We conducted field studies to determine the effect of two atrazine rates (1.7 and 3.4 kg/ha) and two N rates (135 and 225 kg/ha) at one location and two atrazine rates (2.2 and 4.5 kg/ha) at a second location on hay, corn grain, and silage yields when corn was sod planted in five grass species.

Soils were classified as a Wheeling fine sandy loam, a member of the Ultic Hapludulf fine‐loamy mixed family, and a Wharton silty clay loam, a member of the Aquic Hapludult, clayey, mixed mesic family for the two locations, respectively. Grass species used for sod were smooth brcmegrass (Bromus inermis Leyss.), orchardgrass (Dactylis glomerata L.), timothy (Phleum pratense L.), Kentucky‐31 tall fescue (Festuca arundinacea), and Kentucky bluegrass (Poa pratensis L.).

Significant differences in grain, silage, and hay yields were found due to associated grass and rates of atrazine. Highest grain and silage yields were produced in bromegrass sod at both rates of atrazine with the high N rate. Corn yields were reduced at the lower rate of atrazine at Point Pleasant when planted in orchardgrass, tall fescue, anti bromegrass. Yields were generally reduced by using the high rate of atrazine at Morgantown. Corn yields were increased by increasing N rate. Sod planted corn had significantly more yield than conventionally planted corn. Bromegrass, orchardgrass and fescue produced excellent regrowth and hay yields when field was treated with 1.7 kg/ha atrazine after a corn crop. Bromegrass had a stimulating effect on corn growth at both locations.

Soil moisture was higher and soil temperature lower in sod‐planted corn than in tilled corn.
Influence of Long‐Term Soil Fertility Treatments on Weed Species in Winter Wheat1
Authors: Banks P. A. , Santelmann P. W. , Tucker B. B.
Published: July 2010

Winter wheat (Triticum aestivum L. em Thell.) plots that had received various conventional soil fertility treatments continuously for 47 years were evaluated as to the weed species present, and were compared to other cropping situations. This was done to evaluate the influence of continuous fertility treatments on weed types and populations. Replicated soil samples were collected, the indigenous weed seeds were germinated in greenhouse flats, and the species identified. Six species of weeds predominated. Generally, the lowest total numbers of weeds were observed on the plots which had not been fertilized, and populations increased as various nutrients were added. Highest total weed numbers were present on the plots which had received applications of N, P, K, and lime. Most individual species followed the trend of the total plant numbers except for evening primrose (Oenothera laciniata Hill), carpetweed (Mollugo verticillata L.), and henbit (Lamium amplexicaule L.). Highest numbers of evening primrose occurred on the unfertilized plots with decreasing populations as fertility treatments became more complete. Carpetweed and henbit numbers were greatest in the plots receiving P alone or N plus P. Similar species were found on nearby soils which had grown cotton or winter wheat commercially for 25 and 40 years respectively. High numbers of purslane (Portulaca oleracea L.) were observed on both of these soils which were not present in any of the long term fertility treatments. Many more plant species and higher total plant numbers were found in soil from a native grass prairie site.
Reflectant Induced Modification of Soybean Canopy Radiation Balance V. Longwave Radiation Balance1
Authors: Baradas Maximo W. , Blad Blaine L. , Rosenberg Norman J.
Published: July 2010

Potential water‐savings and increased water use efficiency may result from reflectant‐induced modification of the canopy radiation balance. This report is one of a series of papers describing reflectant treatment effects on the radiation balance. The objective of this study was to evaluate the effect of the reflectant treatment on the longwave balance over soybeans [Glycine max (L.) Merr.].

Average ratios of the flux densities of net longwave to global radiation on 3 and 9 August, were 0.251, 0.239, 0.257, and 0.241 over ‘Amsoy’ treated, Amsoy untreated, ‘Beeson’ treated, and Beeson untreated areas, respectively. Corresponding global radiation reflection coefficients were 0.207, 0.194, 0.235, and 0.211.

The flux density of outgoing longwave radiation was greater from the reflectorized crop than from the untreated crop. This was due both to an increase in the reflection of incoming longwave radiation and to an increase in the flux density of emitted radiation. The increased reflection of longwave radiation was due to a reduction in the longwave absorptivity; the increased emission was caused by the higher temperature of the treated canopy.

The reduction of net radiation over the treated areas resulted from the increased outgoing longwave radiation and from the increased reflection of global radiation. Both processes contributed about equally to the observed differences in the net radiative fluxes between treated and untreated canopies. A mechanism of radiation balance modification by reflectants is proposed to explain the observed changes in net radiation.
Development of Cotton Fruit II. Accumulation and Distribution of Mineral Nutrient1
Authors: Leffler H. R. , Tubertini B. S.
Published: July 2010

Previous research on nutrient distribution in cotton (Gossypium hirsutum L.) has generally been conducted on a crop canopy base. To enable measurement of mineral nutrient demand by developing cotton bolls, it was necessary to examine the distribution of minerals among fractions of cotton bolls at specific developmental stages.

Distribution of N, P, K, Ca, Mg, and Mn among the bur (carpel walls), seed, and fiber fractions of cotton bolls was measured between 10 days after flowering and maturity. During the initial 3‐week phase of boll enlargement, the bur accumulated reserves of N, P, and Mg which were subsequently drawn upon, presumably by the seed and fiber, during later development. The bur continuously accumulated K; bur K concentration was 5.5% at maturity. Concentration of most minerals in the seed declined initially, but then increased markedly later. The major mineral accumulated by the seed was N. At boll opening, over 90% of the boll N was in the seed. The fiber accumulated minerals during the first 5 weeks of development, but lost most of them during the final 3 weeks. The most abundant mineral in the fiber was K.

Redistribution of minerals among the boll fractions appeared to have occurred. If it did, it could have partially accounted for the final patterns of mineral distribution. The data suggested that the boll remained a physiological continuum throughout development.
Effect of Increasing Foliage and Soil Reflectivity on the Solar Radiation Balance of Wide‐row Grain Sorghum1
Authors: Fuchs M. , Stanhill G. , Moreshet S.
Published: July 2010

Excessive radiant heat load limits the growh of plants in dryland farming during the rainless summer. The use of reflectants to control the radiation balance in field conditions is examined here.

Modifications of the solar radiation balance in a wide‐row sorghum [Sorghum bicolor (L.) Moench ‘726’] crop grown on a dark brown grumusol (Chromoxererts) were obtained by spraying a white kaolin suspension on 1,000 m2 field plots. Treatments consisted of separate applications of the kaolin on the foliage and on the soil surface, and combined applications on both the foliage and the soil.

Radiation transfer equations were used to quantify the effect of the various treatments on the solar radiation absorption of the foliage, and of the soil. These equations account for the presence of direct and diffuse components in the downward solar flux and make specific reference to a simplified definition of the radiation scattering properties of the foliage and the soil. Measurements of the diurnal variation of the solar radiation reflection above each experimental plot and fisheye determinations of the foliage distribution validated the simplifying assumptions used in deriving the transfer equations. With some additional assumptions the equations are extended to predict absorption by the foliage and the soil from daily totals of the global radiation.

The reflectivity of the foliage increased by 24% immediately after spraying kaolin on the canopy. A 17% increase persisted 5 weeks later. The corresponding seasonal net solar absorption was reduced by 6%. The soil treatment doubled the solar reflectivity of the soil, causing an 18% decrease of the solar absorption by the soil. The increased reflected solar flux from the soil surface was partly intercepted by the foliage, and produced a 9% increase of absorption by the foliage. The application of kaolin to both the foliage and the soil resulted in very little change in the absorption by the canopy, the whitening of the foliage being offset by the addition of the radiation reflected by the soil, but was most effective in increasing the solar reflection from the field. Larger reductions of the canopy solar radiation balance can be expected by improving the dispersion of the kaolin coating on the entire foliage.
Biological Significance of Reed Canarygrass Alkaloids and Associated Palatability Variation to Grazing Sheep and Cattle1
Authors: Marten G. C. , Jordan R. M. , Hovin A. W.
Published: July 2010

Total basic alkaloid concentration of reed canarygrass (Phalaris arundinacea L.) is negatively correlated with palatability (selection when a choice is offered) of the grass to ruminant animals. The significance of these alkaloids to ruminants not offered a choice of pasture forage remained unknown. Our objectives were to determine whether alkaloid concentration and alkaloid type differences among reed canarygrass genotypes affect animal performance, grass intake, and health of grazing sheep and cattle.

Replicated pastures representing two primary alkaloid types (gramine vs. tryptamine‐carboline) and two alkaloid concentrations were primarily established from eight clones of reed canarygrass. During 1973 and 1974, these pastures were grazed by lambs and during 1975, by steers.

Total alkaloid concentration of the grass was highly negatively associated with average daily gains by lambs and steers (r= —0.91, —0.90, and —0.91 for 1973, 1974, and 1975, respectively). Alkaloid concentration was highly negatively correlated with an estimate of voluntary intake (r = −0.85) by lambs not offered a choice of reed canarygrass genotypes, but alkaloid concentration was not usually overtly associated with voluntary intake by steers. Animals had more diarrhea when grazing high‐alkaloid plants and when grazing tryptamine‐carboline‐containing compared to gramine‐containing plants. This physiological upset may have been a major contributor to reduced animal gains.

Breeding or managing reed canarygrass cultivars for lower alkaloid concentration per se, and breeding for tryptamine‐carboline‐free (gramine‐containing) cultivars, should provide pasture that has improved animal performance potential. “Phalaris staggers” or “sudden death” were not incited in sheep or cattle grazing exclusively reed canarygrass that had very high indole alkaloid concentrations. This indicated that these disorders, thought to be caused by indole alkaloids in animals grazing Phalaris species, are very likely not caused by indole alkaloids alone.

We have conclusively demonstrated that palatability differences and their associated alkaloid concentration differences among reed canarygrass genotypes have a substantial biological significance for grazing lambs and steers.
Yields and Nutrient Accumulation by Determinate Soybeans, as Affected by Applied Nutrients1
Authors: Terman G. L.
Published: July 2010

Most published results with southern determinate soybeans [Glycine max (L.) Merr.] are concerned with only a single fertilizer treatment and/or one or two sampling dates. Consequently, field experiments were conducted to determine effects of applied N and K on dry matter yields, nutrient concentrations, and nutrient uptake at several sampling dates and on final grain yields. Rates of 0, 86, and 172 kg of applied K/ha and 0 and 70 kg of N were compared in a field experiment on Sango sil (Ochrepic Fragiudult) in 1973 and K rates of 0, 75, and 150 kg/ha in 1974.

Marked responses to applied K were obtained. Maximum dry matter yields and nutrient uptake occurred during the early pod filling stage of growth. Dry matter yields then declined as a result of greater loss of leaf and petiole drop than of increase in grain filling. Concentrations of K in leaves, topgrowth, and grain increased with amount of applied K, but top trifoliate leaf blade concentrations were lower than some published recommended levels for high yields. Marked reciprocal relationships occurred among concentrations of K and Ca or Mg in top trifoliate leaves and topgrowth.

Several combinations of N, P, K, and S foliar‐ and soil‐applied during pod filling were also compared in a 1976 pot experiment on Sango sil. Grain yields and concentrations of each applied nutrient were increased in leaves and grain. Pod numbers were highly correlated with grain yields.