bluuebunny/crossref_metadata_2025 huggingface dataset:
Conventional and Suspension Limestone Influence on Soil Chemical Properties and Corn and Soybean Yields1
Authors: Bertsch P. M. , Alley M. M.
Published: July 2010

Conventional and suspension limestone materials prepared from identical limestone rock were evaluated to compare their reaction rates for neutralizing soil acidity. Measurement of the limestone materials influence on N NH4OAc extractable Ca and Mg and N KCl exchangeable Al, soil pH, and crop yields were utilized to study reaction rates. Field plots were established on a Goldsboro sandy loam (Aquic Paleudults) and an Emporia loamy sand (Typic Hapludults) in the Coastal Plain region. Corn was the indicator crop for the Goldsboro soil, while soybeans were grown on the Emporia soil. Treatments ranged from 0 to 13.94 and 0 to 4.48 metric tons/ha on the Goldsboro and Emporia soils, respectively. Initially, extractable soil Ca and Mg increased and exchangeable Al decreased more rapidly with suspension limestone applications than with conventional treatments. Regardless of material, lime rates of 2.24 metric tons/ha and greater increased surface soil pH 2 weeks after limestone application on both soils. Sixteen weeks after lime treatment, increases in extractable Ca and Mg and soil pH, and decreases in exchangeable Al were approximately equal for both materials. Yield responses varied with lime treatments at both locations.
Influence of Concentrations of K and Mg in Nutrient Solutions on Sorghum1
Authors: Ologunde O. O. , Sorensen R. C.
Published: July 2010

Several interactive effects of K and Mg are present both in plants and soils. Very limited information is available on the interaction of these two elements in sorghum [Sorghum bicolar (L.) Moench] plants. Thus a greenhouse experiment was conducted in sand culture to determine the main and interactive effects of K and Mg in the medium on growth and composition of sorghum plants.

Nutrient treatments included seven concentrations each of K as KCI, and Mg as MgCI2. Seventeen of the possible 49 treatment combinations were used in a central composite factorial design with two replications. A sorghum hybrid (‘RS 671’), its male (‘Tx 415’), and female (‘Redlan’) lines were used. Aboveground parts of plants were harvested at 25, 50, and 75 days after emergence.

The three sorghums showed similar effects for most treatments. Dry matter production was not affected by concentrations of K and Mg until 50 and 75 days after emergence, respectively. At final harvest, maximum top dry matter production was obtained at the optimum rates of 195 and 38 ppm of K and Mg, respectively. Effects of K were not affected by concentrations of Mg and vice versa.

As long as the absolute amounts of K and Mg in the growth medium were adequate to meet the demands of the plants, the K/Mg ratio in the growth medium varied widely without causing any adverse effect on dry matter production of the plants.

Plant nutrient concentrations were determined by rate of growth and consequent nutrient dilution. However, high levels of K in the growth medium reduced plant Mg concentrations. Also increased rates of applied Mg increased the concentrations of P in the plants.

Increases of K/Mg ratio in the growth medium were associated with reductions in Mg, Ca, and P concentrations in the plant, but the sum (K + Mg + Ca) remained constant.

These results show that K is probably more critical than Mg in the nutrition of sorghum, but low levels of both created growth problems particularly as the growth period of the plant exceeded 50 days. Two parent lines and a hybrid showed limited differences in K and Mg nutrition. The K/Mg ratio in the growth medium was not useful in predicting amount of growth.
An Enzyme Kinetic Equation to Estimate Maize Development Rates1
Authors: Kiniry J. R. , Keener M. E.
Published: July 2010

While use of thermal units to predict development rate is very old, nearly all thermal unit equations are empirical and have no theoretical basis. The poikilotherm equation is unique in that it has a theoretical basis and accounts for both high and low temperature nonlinear development rate responses; however, this equation had never been applied to field grown plants. In this study, the equation, along with more traditional thermal unit equations, was applied to field grown maize (Zea mays L.).

Three hybrids of maize were grown in two plantings at two locations in each of 2 years. The coefficient of variation across mean unit sums for each planting was used as the criterion for comparing six other equations with the poikilotherm equation. Other equations used were the growing‐degree‐day (GDD) 40, the GDD 50, the 50 to 86 cut‐off, the heat‐stress, the Ontario corn heat unit equations, and day count.

The GDD 40 equation best described the planting to tassel initiation interval. Silking appeared to be delayed by high temperatures, thus the tassel initiation to silking interval was best described by the heatstress equation. There appeared to be no difference between different thermal unit equations for the silking to black layer formation and planting to black layer formation intervals. Even though the poikilotherm equation was based on physiology of the plant, it was no better than the other methods of accumulating heat units.
Salt and Water Stress Effects on Germination of Guayule Seeds1
Authors: Miyamoto S. , Sosnovske K. , Tipton J.
Published: July 2010

In view of developing domestic rubber productions, guayule (Parthenium argentatum G.) is receiving renewed interest; however, necessary cultural practices have not been well established, especially under saline conditions. Studies were performed, therefore, to evaluate salt and soil water stress effects on seed germination. The test materials included four USDA selections (11646, 11604, 11633, and A48118) and one cultivar (593). Petri dish solution cultures were used for evaluating salt effects, and two sandy soils (Typic Torrifluvents and Typic Torripsamments) placed in petri dishes were used for studying soil water stress effects. Results indicate that seed germination may be reduced by approximately 25%, due to salinity of salt solutions ranging from 7 to 19 mmho/cm with a descending order of tolerance of 11646, 593,11604 = 11633, and A48118. Selection 11646 showed excellent characteristics as well as high salt tolerance. Specific ion effects were insignificant when tested in salt solutions having mixed ion compositions. Soil water stress needs to be controlled at less than about 0.8 bar if germination is to be accomplished without adverse effects of water stress.
Gibberellic Acid Influence on Aged and Unaged Barley Seed Germination and Vigor1
Authors: Huber Thomas A. , McDonald Miller B.
Published: July 2010

Gibberellic acid (GA) is presently used to break dormancy of cereal grains prior to germination testing. The increased use of vigor testing has led to an interest in the applicability of GA in breaking dormancy prior to vigor testing. The present study identifies the vigor criteria which are most suitable for the incorporation of GA in the testing procedure. The influence of GA (10 μM), artificial aging (41 C, 100% RH, 4 days), initial vigor level (high, medium, and low) and various interactions of these factors on the germination and vigor assessment of ‘Himalaya’ barley (Hordeum vulgare L., cv. Himalaya) seeds were determined. High vigor seeds exhibited higher germination, higher dry weight production and longer mean plumule than did medium and low vigor seeds. Artificial aging decreased germination of all vigor levels, with the greatest decrease exhibited by medium and low vigor seed lots. Artificial aging also decreased the mean plumule length and dry weight production. Exogenous GA slightly decreased the germination of aged and unaged seeds at Day 7, but not at Day 4. This decrease, however, did not affect germination test interpretations. Gibberellic acid also increased the mean plumule length but did not affect dry weight production or the number of abnormal seedlings. We conclude that physiological levels of GA did not adversely affect germination test results. Furthermore, GA did not affect the interpretation of vigor tests when measuring germination (7 and 4 day count) or dry weight production. However, GA did increase plumule length which suggests that this is a poor vigor criterion when using GA to break dormancy of barley seeds.
Alkaline Oxidation Method for Determination of Total Sulfur in Plant Materials1
Authors: Tabatabai M. A. , Chae Y. M.
Published: July 2010

Current wet digestion methods available for determination of total S in plant materials are unsafe and usually give inaccurate results.

A rapid and precise method of determining total S in plant materials has been developed. The plant sample is heated with NaOBr solution to oxidize plant S compounds to sulfate, and the sulfate thus formed is reduced to H2S by a modified Johnson‐Nishita procedure and determined colorimetrically as methylene blue. Its results for total Sare generally higher than those obtained by the HCIO4‐digestion method, suggesting possible loss of S, as gases, or incomplete oxidation of S during digestion of plant samples with HCIO4. In addition to being safe, digestion of plant samples with NaOBr is more rapid than with HCIO4. By using a bank of 10 distillation units, a single operator can perform 60 analyses in a normal working day.
Water Potential Evaluation of Three Germination Substrates Utilizing Polyethylene Glycol 20,0001
Authors: Berkat Omar , Briske D. D.
Published: July 2010

Numerous problems exist in controlling substrate water potentials for germination investigations. Therefore, an evaluation of three germination substrates was conducted at four water potentials maintained by various concentrations of polyethylene glycol 20,000 (PEG). The substrates were: 1) PEG saturated paper (paper), 2) paper on PEG saturated vermiculite (vermiculite), and 3) paper on foam floating on PEG solution (foam). A water vapor seal was placed on half of the trays prior to placement in a controlled environment. Germination substrate water potentials were measured with a thermocouple psychrometer every 2 days for a 2‐week period. Germination substrate water potentials never fully equilibrated with the solution water potentials. Germination substrate water potential in the nonvapor sealed trays decreased 0.8 MPa within a 2‐day period while vapor sealed trays showed no appreciable decrease. At the end of the 12‐day period substrate water potentials had decreased 0.15 and 1.85 MPa for the vapor sealed and nonsealed trays, respectively. When both vapor‐sealed and non‐vapor sealed trays were considered, vermiculite and foam substrates exhibited a significantly higher water potential than paper. When only the vapor‐sealed trays were considered, the influence of type of germination substrate was reduced, although vermiculite exhibited a higher water potential than the foam. The foam substrate was considered most desirable because of ease of preparation and tendency to avoid accumulation of free‐standing solution.
Weed Control in Corn Planted into Untilled Winter Wheat Stubble1
Authors: Burnside Orvin C. , Wicks Gail A.
Published: July 2010

As reduced tillage production systems expand in the Great Plains, a critical need will be non‐tillage methods for controlling established weeds prior to planting the crop. This research dealt with finding selective weed control methods for corn (Zea mays L.) in an ecofarming system consisting of a winter wheat (Triticum aestivum L.)‐corn‐fallow rotation on a Sharpsburg silty clay loam (Typic Argiudolls) at Lincoln and a Holdrege silt loam (Typic Argiustolls) at North Platte, Nebraska. Both established and subsequently emerging weed species must be selectively controlled without tillage in order to better conserve the soil, water, energy, and labor requirements in this marginal corn production area. This research has as an objective the moving of dryland corn production further west in the Great Plains region. Adequate control of annual grass weeds as a group was more difficult than control of broadleaf weeds. The more difficult to control weed species were velvetleaf (Abutilon theophrasti Medic.), fall panicum (Panicum dichotomiflorum Michx.), large crabgrass [Digitaria sanguinalis (L.) Scop.], and clammy groundcherry (Physalis heterophylla Nees). Weed yields were the lowest and corn yields were the highest on plots receiving atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine] at 2.2 kg/ha, cyanazine (2‐[[4‐chloro‐6‐(ethylamino)‐s‐triazin‐2‐yl]amino]‐2‐methyl‐propionitrile) at 2.8 kg/ha, or a combination of the two at 0.9 + 1.9 kg/ha. Four foliar‐active herbicide treatments—2,4‐D [(2,4‐dichlorophenoxy)acetic acid] at 1.1 kg/ha, 2,4‐D at 1.1 kg/ha + 9.4 liters/ha Sunspray 11E oil, paraquat (1,1'‐dimethyl‐4,4'‐bipyridinium ion) at 0.3 kg/ha, and glyphosate [N‐(phosphonomethyl)glycine] at 0.6 kg/ha—were equally effective for controlling established weeds and maintaining high corn yields when combined with the s‐triazine herbicides. The no‐till farmer has a number of herbicides available which will selectively destroy established and subsequently germinating weed species in corn without tillage.
Field Evaluation of Reference Crops in the Study of Nitrogen Fixation by Legumes Using Isotope Techniques1
Authors: Wagner George H. , Zapata Felipe
Published: July 2010

Nitrogen fixed by a legume crop can be measured in a field fertilized with labeled 15N when a suitable non‐fixing reference crop is grown also. Legume and reference crop, respectively, are used with 15N fertilizer to determine available soil plus fixed N and available soil N. Nitrogen derived from fixation is computed from the difference between these two estimates of N availability. Suitability of a reference crop depends on its utilization of fertilizer and soil N in the same proportion as the legume crop. Because this cannot be evaluated directly, the acceptability of reference crop data was examined by determining whether the proportion of fertilizer and soil S taken up by legume and non‐fixing reference crops is the same. Various reference crops for determining N fixation by broadbean (Vicia faba L.) and by soybean (Glycine max L. Merr.) were examined by this approach in field experiments on a Typic Eutrocrept using 15N and 35S labeled ammonium sulfate to determine plant available amounts (A‐values) of N and S in the soil.

Nitrogen A‐values for broadbean were clearly higher than for any of the non‐fixing crops at two harvest dates. At physiological maturity of the legume, N fixation estimated from A‐value comparisons was approximately 140 kg/ha. Sulfur A‐values were reasonably similar among all crops studied but somewhat lower for oil radish (Raphanus sativus L.) which proved to be an inappropriate reference because it took up much more S than the other crops.

Nitrogen A‐values for inoculated soybeans at the R3 stage of maturity were similar to those for the several reference crops including non‐nodulating soybeans. At stage R6, N fixation was clearly evident from A‐value comparisons but no greater than 60 kg/ha. By creating a N deficient condition in the soil using sucrose to immobilize N in an experiment with soybeans, the percentage of N in the crop derived from fixation was increased from 30 to 80%.
Evaluation of a Dual‐Radioisotope Instrument for Measuring Leaf Conductance and Photosynthesis1
Authors: Ramos C. , Hoffman G. J. , Hall A. E.
Published: July 2010

Modifications in both the design and operation of the dual‐radioisotope instrument are described. The accuracy and reliability of the modified instrument were then evaluated in both laboratory and field tests. Leaf conductance and net CO2 exchange rates determined with this instrument and by gas exchange methods in the laboratory were similar for both corn (Zea mays L.) and wheat (Tritictim aestivum L.). A field test of the instrument on barley (Hordeum vulgare L.) subjected to two levels of salinity gave coefficients of variation which indicated that errors attributable to the instrument and/or the plant material were less than 35% for leaf conductance and 16% for photosynthesis. The instrument provides rapid, simultaneous measurements of leaf conductance and photosynthesis under field conditions.
Forage Quality for Sheep and Chemical Composition Associated with Sulfur Fertilization on a Sulfur Deficient Site1
Authors: Jones M. B. , Rendig V. V. , Torell D. T. , Inouye T. S.
Published: July 2010

Improvements in forage quality and yield have resulted from application of S fertilizer. The purpose of this study was to relate forage composition changes associated with S fertilization to quality, as measured by lamb growth, efficiency of feed eaten by lambs, in vitro digestibility, and blood serum sulfate levels. Five rates of S were applied on a Sutherlin soil series (Ultic Haploxerolls) in each of 2 successive years to two sets of plots, one set seeded to subclover (Trifolium subterraneum L.) (designated “clover‐grass”), the other to ryegrass (Lolium multiflorum L.). The ryegrass plots were also fertilized with N, and all plots received applications of P and K. The forage was harvested as hay, ground, pelleted, and fed to lambs in two feeding trials with an average duration of 60 days.

Sulfur concentrations ranged from 0.13 to 0.24% in the clover‐grass and from 0.09 to 0.22% in ryegrass. Protein ranged from 10.3 to 13.1% in the clover‐grass, and from 6.3 to 8.0% in the ryegrass. The N/S ratios ranged from 8 to 13 for the clover‐grass and from 6 to 13 for ryegrass.

Application of S to the soil increased the average daily gains (ADG) of lambs for the two trials, from 141 to 186 g for the clover‐grass, and from 32 to 84 g for the ryegrass. Ninety percent of the maximum ADG (defined as a critical value) was obtained at 0.19% S in the clover. A critical value is not given for ryegrass since ADG increased with each increment of S added, including the highest level of S applied. This was likely due to N being more limiting than S in the diet of the lambs. Blood serum sulfate‐S in the lambs was more closely related to % S in clover‐grass forage (r2 = 0.76) than to % S in ryegrass (r2 = 0.50). A good relationship (r2 = 0.90) was found between serum sulfate‐S level and sulfate‐S intake for both forages. Blood sulfate was related to growth rate of lambs by a negative exponential function, with estimated critical values of 30 and 39 µg/ml, respectively, for the ryegrass and the clover‐grass hay pellets.

An average of 11 kg feed/kg gain was required for sheep on clover‐grass with zero S applied. This dropped to nine where S was applied. On ryegrass this ratio was 48 on the zero S treatment, but it dropped to an average of 18 with S applied.
Field Comparison of the Nitrogen‐15 and Difference Methods of Measuring Nitrogen Fixation1
Authors: Talbott Helen‐Jean , Kenworthy W. J. , Legg J. O.
Published: July 2010

Further investigation of the methods of evaluating N2 fixation under field conditions is essential, since the accuracy and reproducibility of the method of measurement have profound effects on the results of an experiment; and, opinions differ concerning which method provides the best estimates. The amount of N2 fixed and the percentage of total plant N from biologically fixed N in field‐grown soybeans [Glycine max (L.) Merr.] measured by the difference method were compared with corresponding estimates from a 15N‐tracer technique in which 15N‐labeled soil organic matter is used as the tracer material. In 1977 and 1978, six N2‐fixing soybean genotypes were grown in rows alternating with rows of a nonnodulating genotype (Clark rj1 rj1) in replicated field plots on a Mattapex silt loam (fine‐silty, mixed, mesic Aquic Hapludult) where the 15N was incorporated into the soil organic fraction. The difference method compared total N contents of the N2‐fixing and adjacent nonnodulating plants. The 15N method determined the dilution in the N2‐fixing plants of soil‐derived 15N by symbiotically‐fixed N. Plants were sampled at 49, 70, and 91 days after planting and at full maturity in 1977, and at 62 and 112 days after planting in 1978. Sources of variation for the estimates were identified as the total N accumulation in the nonnodulating genotype for the difference method, and the 15N concentration in the nonnodulating genotype for the 15N method. Estimates from the difference and 15N methods for the amount of total N fixed were highly correlated (r = 0.89 for 1977, r = 0.92 for 1978). The percentage of total N fixed varied between the two methods (r = 0.32 for 1977, r = 0.69 for 1978) which was attributed to spatial variation of available soil N. The 15N method provided more accurate estimates for the percentage of total N fixed because the 15N concentration was less variable than the total N accumulation in the nonnodulating genotype.
Backhoe‐Mounted Soil‐Coring Machine
Authors: White R. J. G.
Published: July 2010

A hydraulic soil‐coring machine has been designed and constructed to attach to the arm of a tractor‐mounted backhoe. The system reduces the passes through a plot with sampling equipment and also allows samples to be taken with the tractor outside the plot when soil and/or crop conditions do not allow access. It has been successfully used in summer row crop experiments for: (i) taking small diameter (to 5 cm) intact soil cores to a maximum depth of 2 m, (ii) inserting access tubes for soil‐water monitoring using a neutron probe, and (iii) placing large diameter tubes (up to 30 cm) to shallow depths (45 cm) for nutrient isotope studies.
Grain Protein Percentage, Kernel Hardness, and Grain Yield of Winter Wheat with Foliar Applied Ureal1
Authors: Altman D. W. , McCuistion W. L. , Kronstad W. E.
Published: July 2010

In the Pacific Northwest a major constraint to growing hard red winter wheat (Triticum aestivum L.) is the consistently low grain protein percentage observed. Foliar fertilization of winter wheat offers a potential for increasing grain protein percentage when applied around flowering. The main objective of this study was to determine the effect of foliar urea sprays on grain protein percentage, grain yield, and kernel hardness of 10 genotypes of winter wheat when grown in the field under four diverse environments. Also, immature spikes were analyzed after foliar treatments for percent protein, and optimal grain uptake of foliar applied N was measured under controlled conditions using 15N labelled urea. Foliar sprays of urea increased grain protein percentage by 16 and 10 % and yield by 8 and 3% over the control of no applied urea in two environments. Combinations of topdressing and foliar sprays produced yields equivalent to standard topdressed plots at all locations and increased grain protein percentage by 12 and 9% in two of the four environments tested. Foliar applications did not alter kernel hardness overall. Significant genotype X N treatment interactions were found for grain protein percentage, grain yield, and kernel bardness. Spike protein analysis at flowering showed N treatment effects 2 weeks after foliar applications in the field, and the ranking of treatments corresponded closely with that determined by grain analysis at harvest. Uptake of N from foliar sprays was also confirmed with a mean of 44.1 % of applied 15N recovered in grain samples. Genotypes differed for I5N recovery rates in the grain from 48.3% for ‘Stephens,’ a low protein soft white cultivar, to 39.9% for ‘Centurk,’ a higher protein hard red cultivar. Daylength after treatment also affected recovery rates with 41.4 and 46.9% of applied 15N being recovered for 12 and 18 hours respectively.
Sulfur Nutrition of Rice. III. A Comparison of Fertilizer Sources for Flooded Rice
Authors: Samosir Solo , Blair Graeme J.
Published: July 2010

Sulfur deficiency in rice (Oryza sativa L.) is becoming a more significant constraint to rice yields as the use of high analysis, low S‐containing fertilizers increases. There is a wide range of sulfatic fertilizers available and these have not been tested, to any degree, under flooded conditions. A pot experiment was conducted on a low fertility Paleudult soil to test the S‐supplying capacity of ammonium sulfate, gypsum, elemental S, and sulfur coated urea (SCU) applied at 30 kg S/ha to flooded rice. At 25 days after transplating (dat), fertilizer source had no significant effect on total top yield and S uptake was lower in the control, elemental S and SCU treatments. By 50 dat S deficiencies were evident in the control and SCU treatments where tiller number, yield, and % S levels were decreased. Sulfur uptake from SCU was not significantly different from the zero S control over the 113 day growing period. At maturity yields and S uptake were not significantly different between the gypsum, elemental S (100% <60 mesh), and ammonium sulfate sources. These results confirm the suitability of fine (100% <60 mesh) elemental S as a S source for rice, and show that S from SCU is not available to flooded rice at least in the first crop after application.
Influence of Mycorrhizal Fungi on the Mineral Nutrition and Yield of Onion in Saline Soil1
Authors: Ojala J. C. , Jarrell W. M. , Menge J. A. , Johnson E. L. V.
Published: July 2010

In a number of studies, salt‐affected plants have been found to contain lower P concentrations than non‐salinized control plants. This study was performed to evaluate the ability of two vesicular‐arbuscular mycorrhizal fungi (VAM) to improve the yield and salt tolerance of onion (Allium cepa L. var. Burpee hybrid 5276) by facilitating P uptake from a saline soil. Onion was grown in a Delhi loamy sand soil (mixed, thermic Typic Xeropsamment) in the glasshouse under ambient light conditions. Plants infected with Glomus fasciculatus and G. monosporus VAM had higher bulb and total onion dry weights than nonmycorrhizal plants in P deficient soil at low (−0.06 MPa bars) irrigation water solute potential (Ψ3), intermediate (−0.20 MPa Ψ3), and high (−0.41 MPa). Plants infected with G. fasciculatus yielded significantly more than G. monosporus plants at low (Ψ3 = −0.06 MPa) and high (Ψ3 = −0.41 MPa) salinity; at Ψ3 = −0.20 MPa bars, yields were not significantly different for mycorrhizal plants. Mycorrhizal infection with both fungi tended to decrease linearly with increasing salinity, although it remained high (58 to 46%) even at high salinity. As salinity increased, nonmycorrhizal plants developed lower concentrations of P, Mg, and K in shoot tissues, K in bulb tissues, with lower total uptake (mg plant−1) of Ca, Mg, K, Zn, and Mn. Mycorrhizal onion had greater concentrations of P and K in shoot tissues, P in bulb tissues, and greater P, Ca, Mg, Na, K, Zn, and Fe total uptake than nonmycorrhizal plants at intermediate soil salinity. Tissues of mycorrhizal plants contained only 70 % as much Mn as nonmycorrhizal plants; high Zn and Fe concentrations were reduced in plant tissues at high salinity compared with intermediate and low salinity. Improved nutritional status of onion plants due to mycorrhizal fungi is at least partially responsible for increased plant growth under saline conditions, although other mechanisms may be involved.
Changes in Composition of Alfalfa, Red Clover, and Birdsfoot Trefoil during Autumn1
Authors: Collins Michael
Published: July 2010

Considerable research has been conducted to evaluate the influence of harvest management of alfalfa (Medicago sativa L.) during late summer and autumn on persistence and subsequent forage yields. These studies generally have not included data on changes in forage quality during autumn. The objective of this experiment was to measure changes in forage yield and composition of alfalfa, red clover (Trifolium pratense L.), and birdsfoot trefoil (Lotus corniculatus L.) in response to delay of harvest during autumn. Small plots of each species were seeded on Plano silt loam soil (fine‐silty, mixed, mesic Typic Argiudoll) using chemical weed control. Regrowth was measured following a late August harvest each season. Separate plots of each species were harvested on the average dates of 7, 17, and 28 October and 8 and 19 November during 1979 and 1980. Dry matter yield of alfalfa increased by 16% between 7 and 17 October in 1979 and by 22% in 1980. Yield of all three species declined after the mid‐October harvest in both years. Nitrogen concentration in forage of all species declined between 7 October and 8 November in 1979, and between 7 and 28 October in 1980. In vitro dry matter disappearance (IVDMD) did not change between 7 and 28 October but generally declined by 19 November. Total nonstructural carbohydrate concentration increased between 7 and 28 October and declined thereafter. Neutral detergent fiber concentration in alfalfa did not increase between 7 and 28 October in 1979 but increased after that date. Red clover did not increase in neutral detergent fiber concentration during autumn in 1979. In 1980 forage of all species increased in neutral detergent fiber after 8 November. The concentrations of P, K, and S in the forage of all three species declined during autumn. Red clover was lower in S concentration (0.21 %) than alfalfa (0.32 %) or birdsfoot trefoil (0.29 %). Calcium concentration increased significantly during autumn. The concentration of Mg in all three species remained unchanged or increased during autumn. These results indicate that significant yields of high quality forage were produced following harvest in late August. The three legumes differed in yield but were generally similar in IVDMD and N concentration on a particular harvest date. Forage yield declined more rapidly between 7 October and 17 November than did forage IVDMD or N concentration.
Band Application of Sulfuric Acid or Elemental Sulfur for Control of Fe‐Deficiency Chlorosis of Soybeans1
Authors: Frank S. J. , Fehr W. R.
Published: July 2010

Iron‐deficiency chlorosis can reduce the productivity of susceptible soybean [Glycine max (L.) Merr.] cultivars when grown on certain calcareous soils. Two experiments were conducted to evaluate the use of S and sulfuric acid (H2SO4) for the control of Fe‐deficiency chlorosis of soybeans grown on calcareous Harps (fine‐loamy, mesic, Typic Calciaquoll) soils in the field. In Exp. 1, H2SO4 was applied at eight rates from 0 to 123.5 g/m of row at two depths under the seed, 2.5 and 5 cm. Two cultivars susceptible to Fe‐deficiency chlorosis, ‘Corsoy’ and Pride ‘B216’, were evaluated with each rate in five Iowa environments during 1978 and 1979. In Exp. 2, H2SO4 was applied 5 cm below the seed at the same rates as in Exp. 1, and S was applied at the same depth as a powder at rates equivalent to the amount of S applied in the H2SO4. Corsoy and B216 were evaluated with both chemicals on calcareous soils in four Iowa environments during 1979. Response in both experiments was evaluated by visual chlorosis ratings before flowering, and also by plant height at maturity in Exp. 1. Sulfuric acid significantly reduced chlorosis and increased plant height for both cultivars and depths of placement at the rates of 30.9, 61.8, and 123.5 g/m when averaged across environments. Only at the 123.5 g/m rate did placement of the H2SO4 5 cm below the seed cause a significantly greater reduction in chlorosis score and increase in height than at the 2.5‐cm depth. None of the H2SO4 treatments completely prevented chlorosis in either cultivar. Application of S did not cause significant reduction in chlorosis scores at any of the rates used.
Time Distributions for Describing Appearance of Specific Culms of Winter Wheat1
Authors: Rickman R. W. , Klepper B. L. , Peterson Curt M.
Published: July 2010

Cereal plants emerge and develop tillers in response to the field environment in which they are planted and grown. If the pattern of development of productive culms can be recognized and measured, impacts of different field conditions upon plants can be assessed. This study presents a method for describing emergence and tiller appearance patterns and illustrates the use of these patterns in comparing crop development responses to field environments. Desirable environments will produce uniform populations of culms with regularly spaced appearance patterns while stressful environments cause a variety of irregular patterns.

Characteristics of the populations of appearing culms can be described fundamentally by the logistic distribution function or can be approximated by the normal distribution function. The cumulative form of both functions is a sigmoid curve. The mean of the normal coincides with the 50% appearance time of the logistic. When the dispersion coefficient (s) of the normal function and the rate coefficient (k) of the logistic equation are related by ks = 1.69, the two curves differ by less than 1% of the final population size at any point. Culm appearance populations from good seedbeds appear as normal or logistic curves (considered to be the same curve) when appearances are timed by degree‐days (3°C base). Fifty percent emergence for Stephens winter wheat (Triticum aestivum L.) occurs near 100 degree‐days from planting, and tillers Tl, T2, and T3 occur at about 250, 300, and 375 degree‐days, respectively, in a fertile seedbed with adequate water. Culm appearance data that are not normally distributed may be converted to normal form with transforms or population splitting procedures. The nature of the transformation required to normalize the data may help characterize the field condition causing non‐normal appearance.
Effect of Wind on the Crop Water Stress Index Derived by Infrared Thermometry1
Authors: O'Toole J. C. , Hatfield J. L.
Published: July 2010

A new plant or crop water stress index (CWSI) that depends on interpreting crop or foliage‐to‐air temperature differential (Tf‐Ta) shows promise in both research and irrigation water management. The method relies on the unique relation between Tf‐Ta, and atmospheric water vapor pressure deficit (VPD). However, the method of estimating the upper limit of Tf‐Ta, a critical step in CWSI calculation, was questionable and lacked field validation. We measured the upper limit of Tf‐Ta, and attendant micrometeorological variables on severely water stressed sorghum (Sorghum bicolor L.), corn (Zea mays L.), and bean (Phaseolus vulgaris L.) grown on a Typic Xerotherent, and cotton (Gossypium hirsutum L.) grown on a Typic Torriorthent. Actual measured values of the upper limit of Tf‐Ta ranged from 2.5 to 8.5 °C across crops. The poor agreement between actual and calculated values was analyzed with respect to net radiation, VPD, and windspeed. Windspeed was found to be the primary factor causing erroneous estimation of the upper limit of Tf‐ Ta, and hence CWSI values. Crop water stress index values measured at low windspeed overestimated the level of water stress while those measured at high windspeed underestimated it. Crop specific changes in the boundary layer resistance‐windspeed relationship partially explain the discrepancy between measured and calculated Tf‐Ta, upper limit values. Modification of the CWSI to account for the influence of windspeed is discussed.
Effect of Nitrapyrin on Nitrogen Transformations in Soil Treated with Liquid Swine Manure1
Authors: McCormick R. A. , Nelson D. W. , Sutton A. L. , Huber D. M.
Published: July 2010

Applications of animal manure to soil result in nitrification of applied NH+4 — N and eventual loss of applied N through leaching and/or denitrification processes. In theory, one way to reduce the leaching and/or denitrification losses is through the use of a nitrification inhibitor. Therefore, a field experiment was conducted during the summer of 1979 to determine the effects of nitrapyrin [2‐chloro‐6(trichloromethyl)pyridine] on N transformations occurring within a band of soil‐applied liquid swine manure (LSM). Liquid swine manure (60 t ha −1) containing 0 or 50 mg nitrapyrin active ingredient/liter was injected into Chalmers silty clay loam (fine‐silty, mixed, mesic Typic Haplaquoll). The LSM application provided about 156 kg ha −1 of plant‐available N and nitrapyrin addition rates were 0 and 3 kg ha.−1 Periodically during the 24‐week experiment soil samples were obtained from the LSM application band and analyzed for NH+4 — and NO−3 — N. From 40 to 50% of added organic N was mineralized in the LSM application bands. Ammonium present in bands of LSM not treated with nitrapyrin was oxidized to nitrate within 7 weeks after application. Addition of nitrapyrin to the LSM delayed nitrification for up to 15 weeks after application. Essentially all of the inorganic N had been lost from the LSM that did not receive nitrapyrin by the 11th week after application, probably as a result of sequential nitrification and denitrification. However, in the nitrapyrin‐treated LSM high amounts of inorganic N remained during the entire experiment and greater than 50% of the inorganic N initially present was recovered after 24 weeks. These findings suggest that nitrapyrin was effective in inhibiting nitrification in manure‐treated soil and addition of the inhibitor reduced N losses following manure application.
A Low Cost Microcomputer Data Acquisition System for the Technicon Autoanalyzer1,2
Authors: Winkleman G. E. , Leyshon A. J.
Published: July 2010

A Sinclair ZX81 microcomputer was interfaced with the telemetry output of a Technicon Auto Analyzer II colorimeter using an inexpensive analog interface, A computer program was written in BASIC to monitor the flow of samples within the Auto Analyzer system, measure peak heights, and calculate concentrations. Missing peaks are detected. The system provided totally automatic low‐cost (under $500) data acquisition and handling. Data acquisition and computations by the microcomputer were consistently as reliable as those performed by laboratory personnel. The potential for greater accuracy was believed to exist.
Photoperiod‐Sensitive Tropical Corn as a Potential Source of Biomass or Paper1
Authors: Hammes J. L. , Pendleton J. W.
Published: July 2010

A $1 billion paper and paperboard trade deficit occurs annually in the United States. Research efforts are spent in improving woody species and in identifying new perennial and annual species for such purposes. Five photoperiod‐sensitive, exotic tropical corn (Zea maysL.) cultivars were compared with a local corn hybrid, forage sorghum (Sorghum bicolorL. Moench), and kenaf (Hibiscus cannabinusL.) for their potential biomass production at Madison, Wisconsin on a Ringwood silt loam (Typic Arguidoll) soil. One of the tropical cultivars, ‘Cortazar,’ produced the highest dry matter yield (15.52 t ha−1) and the tallest plants (370 cm). Cortazar's vegetative yield was twice that of the local hybrid and kenaf, but not higher than forage sorghum. A cultural trial conducted with the photoperiod‐sensitive cultivar ‘Tuxpeno Criollo’ indicated that early planting and a moderate plant population would increase biomass yields. Results of this study show that corn has a potential for production as a paper pulp source.
Evaluation of a Soil Inoculant for Improving Corn and Potato Yield and Quality1
Authors: Wolkowski R. P. , Kelling K. A.
Published: July 2010

Corn (Zea maysL.) and potato (Solanum tuberosumL., ‘Russet Burbank’) were grown with and without the addition of the soil additive Symbex at different levels of fertilization. Symbex is marketed as a microbial soil inoculant claiming to accelerate decomposition of crop residue and N fixation. The efficacy of Symbex on the yield and quality of the two crops was evaluated at two sites for corn and one site for potato on a Typic Argiudoll, a Typic Hapludalf, and Typic Udipsamment, respectively, each for 3 years. Rates of fertilizer were 0, 20, 104, and 188 kg ha−1total N applied in the corn studies and 30, 50, and 100% of 756 kg ha−15‐10‐30 starter plus 224 kg ha−1of supplemental N in the potato study. Although both corn and potato yields were increased by fertilization, the use of Symbex did not affect the yield of either crop at any fertilizer rate. Foliar nutrient content of N, P, and K when compared by a paired t test over all fertility levels showed no differences associated with Symbex treatment by either crop. Symbex increased the rate of emergence of potato at all levels of fertility. A trend toward decreased size of grade US1A tubers was observed where Symbex was used.
Herbage Yield and Quality of Filegrass as Influenced by N, P, and K Fertilizer Applications1
Authors: Omaliko C. P. E.
Published: July 2010

The nutrient requirements of filegrass (Anthephora ampulacea, Stapf and Hubb), a potential pasture species, is hardly known. A greenhouse experiment was conducted to study the effects of applied N, P, and K fertilizers on its herbage yield and quality. Four rates of N (0, 100, 200 and 300 kg N/ha−1as ammonium sulfate); three rates of P (0, 33, and 66 kg P ha−1as single superphosphate); and three rates of K (0, 62, and 124 kg K ha−1as muriate of potash) were applied in solution in all possible treatment combinations (36 treatments). Plants were first harvested when 50% of the primary tillers were at early anthesis, A second harvest was made after 4 weeks of regrowth. Fertilizer application at 100 kg N/ha−1rate at least doubled filegrass yield (7.4 vs. 14.8 g pot−1for 0 vs. 100 kg N ha−1rates). Higher rates of N application gave further significant yield increases (19.4 and 19.9 g pot−1for 200 and 300 kg N ha−1, respectively). For the regrowth harvest, yields differed significantly such that 0 < 100 < 200 < 300 kg N ha−1. Filegrass response to applied N is represented by the following regression equations Y = 9.2 + 0.05 × (for first harvest) and Y = 1.39 + 0.018 × (for second harvest). Applied P and K fertilizers did not significantly affect the dry matter yields and concentration of other nutrients in both the leaf and stem fractions. Applied N at 100 kg ha−1rate increased N concentration of the leaf fraction but decreased P, Ca, and Mg of the leaf. Higher N rates, however, increased these nutrients in the leaf blade. Nitrogen application, at all rates, increased the stem concentrations of N from 0.49 to 1.20; P from 0.16 to 0.26; K from 0.87 to 1.12; Ca from 0.11 to 0.56 and Mg from 0.06 to 0.19% on dry matter basis. The dry matter digestibility (DMD) values for both leaf and stem fractions were relatively close (62.8 and 53.4%, respectively). The DMD of each fraction was increased by N application from 45.6 to 65.7 in the leaf and stem when the rate was increased from 0 to 300 kg N ha−1. These results were discussed in terms of herbage production and livestock requirements.
Drying Rates of Spring Triticale Compared to Wheat1
Authors: Clarke John M. , Townley‐Smith T. Fred
Published: July 2010

Some workers have observed that triticale (X‐TriticosecaleWittmack) is slower to dry down after maturity than is wheat (Triticum spp.). Laboratory water uptake rate studies were undertaken with threshed seed of triticale lines in an effort to identify lines with potentially differing drying rates. Drying rates of four lines and one cultivar of triticale were compared with those of two hexaploid wheat (T. aestivumL.) and one tetraploid wheat (T. turgidumvar. durumL.) in windrowed and standing treatments in the field. The experiment was conducted in Saskatchewan, Canada on an Orthic Brown Chernozem; Aridic Boroll soil. Over 2 years, the triticales dried as quickly as, or in some cases, more quickly than the wheats. Similar results were obtained when the rates of kernel water loss after physiological maturity for standing wheat and triticale were compared over 4 years. The triticales tended to reach physiological maturity at higher kernel water concentrations than Glenlea wheat, which may have contributed to the faster drying rates of the triticales.
Crossing Success in Cotton in Arizona as Affected by Irrigation, Number of Flowers Pollinated, and Time of Emasculation1
Authors: Wilson F. D. , Stapp B. R.
Published: July 2010

Retention of crossed bolls is low in plants of cotton (Gossypium hirsutumL.) that are exposed to the high temperatures and water deficits encountered commonly in irrigated desert regions. One purpose of this study was to determine the relationship of the retention of crossed bolls with number of days after irrigation and with the number of pistillate flowers pollinated with one staminate flower. Another purpose was to determine the feasibility of emasculating cotton flowers in the morning of the day of pollination rather than at the traditional time of the afternoon before pollination. For three seasons, flower buds of ‘Deltapine 61’ were hand‐emasculated from 0200 to 0600 h for 10 to 12 days through an irrigation cycle at Phoenix, Ariz. Soil type was Avondale clay loam (a fine, loamy, mixed, hyperthermic Torrifluventic Haplostolls). Groups of pistillate flowers‐10, 15, 20, 25, and 30‐were each pollinated with a single staminate flower from a breeding stock homozygous for R1, red plant color. After each daily session of crossing, 100 open–pollinated flowers were tagged to serve as controls. From this study, we observed 1) a progressive decrease over days in boll set, followed by an increase just before the next irrigation, which illustrates the transitory influence of water stress; 2) that crosses made the 1st week after an irrigation yielded almost as much total hybrid seed as those made for the entire 14‐day period between irrigations; 3) that seed yield loss would not have been severe even if limited amounts of pollen had forced us to pollinate 30 pistillate flowers per staminate flower; and 4) that emasculating flowers even as early as 0200 h on the day of pollination led to some self‐contamination.
Effect of Solar Azimuth and Infrared Thermometer View Direction on Measured Soybean Canopy Temperature1
Authors: Nielsen D. C. , Clawson K. L. , Blad B. L.
Published: July 2010

Measurements of radiative canopy temperature taken with infrared thermometers (IRTs) are strongly influenced by amount of crop cover and amount of viewed soil background. This influence can be minimized by making off‐nadir measurements so that mostly vegetative surface is viewed. But off‐nadir measurements vary with the relative azimuthal positions of the sun and the IRT due to the measurement of true variations in the individually sunlit and shaded canopy elements. The geometrical relationship between solar azimuth and IRT view azimuth on measured canopy temperatures was investigated for soybeans grown at two Nebraska locations in 1982. Soils at the two locations were a Typic Argiudoll and a Typic Ustipsamment. Canopy temperature as measured by the IRT declined linearly as the difference between the solar azimuth and IRT view azimuth increased from 0° to about 110°. As this difference increased to angles greater than 110°, the viewed canopy temperature remained fairly constant at about 0.30°C below the average of the canopy temperatures measured at the four cardinal directions. The declining linear relationship seen for angles between 0° and 110° was found to be more strongly defined during the vegetative growth stages than during the reproductive growth stages. This was attributed to declining heliotropic response of soybean [Glycine max (L.) Merr.] leaves as the canopy ages.