bluuebunny/crossref_metadata_2025 huggingface dataset:
Ephedra Seed Germination1
Authors: Young James A. , Evans Raymond A. , Kay Burgess L.
Published: July 2010

Germination of seeds of gray ephedra (Ephedra nevadensis Wats.) and green ephedra (E. viridis Cov.) must be better understood for propagation on southwestern rangelands of the United States. Investigations were conducted on germination of these species in a wide range of constant and alternating temperature regimes and in different osmotic potentials. Both species germinated over a relatively large range of temperatures. Optimum germination for gray ephedra occurred at constant temperatures ranging from 5 to 20 C and at alternating temperatures of 20/25 C. Green ephedra had optimum germination when combinations of 16 hours of cold temperatures (2 or 5 C) and 8 hours of moderate warm temperatures (15 to 25 C) were followed. Gray germinated faster than green ephedra. Seed storage at room temperature for 12 months after maturity reduced germinability (drastically in the gray ephedra). Low osmotic potentials (created with NaCl or polyethylene glycol) reduced germination more in the green than the gray ephedra seeds. Germination of both species should not limit their use in revegetation except on salty soil in the case of green ephedra.
Relationship Between Corn Yield, Expressed as a Percentage of Maximum, and the N Percentage in the Grain. II. Diagnostic Use1
Authors: Pierre W. H. , Dumenil Lloyd , Henao Julio
Published: July 2010

The purpose of this study was to develop a procedure for determining the amount of N fertilizer needed by corn (Zea mays L.) for maximum yield and economic optimum yield based on the relationship between the relative yield of corn, expressed as a percentage of maximum yield, and the N percentage in the grain. The three major steps in the procedure are: (a) determining the maximum potential yield and yield increase from the relative yield — percent N relationship and the present yield, (b) determining the N‐requirement index (NRI) for different initial relative yields, and (c) calculating the total N requirement.

Two procedures were developed for estimating the NRI, the N required per unit of yield increase, from different initial relative yield levels to maximum or economic optimum yields. One involved simple computations using the treatment means from 13 site‐years of experimental data. The other utilized the individual regressions of yield on N fertilizer from the same experiments to calculate the NRI's to the same marginal productivity point on each site‐year's regression. Good agreement was obtained between the two procedures.

The average NRI's were found to vary from approximately 7.5 kg/q at 90% of maximum yield to 3.5 kg/q at 45% of maximum yield. Evidence was obtained showing the desirability of using NRI values for comparing the efficiency of N use under different environmental and management conditions.

Factors that may affect the relative yield — percent N and the NRI — initial relative yield relationships are discussed briefly. Also, the need for further research, expecially on the effect of different hybrids, is suggested.
Nitrogen and Chloride Uptake by Irrigated Russet Burbank Potatoes1
Authors: Saffigna P. G. , Keeney D. R.
Published: July 2010

Potato production has become a major agricultural enterprise in the central sand plain of Wisconsin. However, little information is available on the effects of irrigation and fertilization practices on dry matter and N accumulation. This field study was established to determine the effect of reducing irrigation and fertilizer N on the dry matter, and the N and Cl in potatoes (Solanum tuberosum L., var. ‘Russet Burbank’) grown on a Plainfield loamy sand (Typic Udipsamment: sandy, mixed, mesic).

Two basic treatments were used. The conventional treatment approximated current recommendations for irrigated potatoes and received 260 kg N/ha (as NH4NO3) in four applications and 45 an irrigation as 2.4 cm applications every 5 days. The improved treatment was intened to minimize leaching of NO3‐N. It received 170 kg N/ha in 10 applications (one as S‐coated urea and nine as NH4NO3) and 27.0 cm irrigation as 1.0 cm applications every 3 days. Chloride (as KCl) accompanied N on a 1:l weight basis. Plants were sampled weekly and analyzed for dry matter, total N, NO3‐N, and Cl.

Plants accumulated 3 to 4 kg N/ha/day from 20 to 70 days after emergence. The maximum N uptake for the whole plant (tops and tubers) was 170 to 250 kg N/ha about 90 days after emergence. The maximum uptake of N in the tops was 125 and 80 kg N/ha in the conventional and improved treatments, respectively. Tuber yields and N uptake were similar between treatments with tubers containing 1.3 to 1.5% N most of the growing season and 130 to 140 kg N/ha (27 to 30 kg N/100 q) at harvest. Plants accumulated 115 to 145 kg Cl/ha, mostly in the tops (90 to 120 kg Cl/ha) with 25 to 40 kg Cl/ha in the harvested tubers.

Nitrate‐N levels were low (<100 mg/kg) in tubers at all samplings. Nitrate‐N was >2,000 mg/kg in the tops during the first half of the growing season and accounted for 10 to 25% of the total N. Due to competitive antagonism, Cl reduced NO3‐N concentration in tops and petioles, and total N in tops and tubers.

The results from this study show that tuber growth and N content were not appreciably affected by substantial reductions in the quantity of fertilizer N (90 kg N/ha) and irrigation (18 cm) applied although foliage dry matter and N accumulation were reduced. However, the additional effort required to effect this small saving in N fertilizer cannot currently be justified.
Maximizing Production Potential of Tall Fescue1
Authors: Kroth Earl , Mattas Richard , Meinke Louis , Matches Arthur
Published: July 2010

Tall fescue (Festuca arundinacea Schreb.) is grown primarily for forage on over 162,000 ha in Missouri. Fescue is managed for spring and summer pasture and for both seed and fall forage production. Spring and fall growth is often stockpiled for late fall and winter feed. This study was conducted to determine the effects of rate and time of N applications and forage management on seed yield, and on quality and yield of forage.

Plots were layed out on established stands of tall fescue on Gerald, Lebanon and Edina silt loams (Umbric Fragiudalf, Typic Fragiudalf, fine mixed mesic; Typic Argialboll, fine montmorillonite, mesic, respectively.) Nitrogen rates on Gerald and Lebanon soils (Southwest Missouri) were 0, 33, 67, 101, and 134 kg/ha in different time combinations, including December, March, June, and August. Forage management included: (a) removal after seed harvest and again in December, (b) stockpile after seed harvest, harvest in December. Nitrogen rates on Edina silt loam (North Missouri) were 0, 67, and 134 kg/ha in different time combinations, including December, March, July, and August. In addition to the two management systems listed above, forage was round baled at the early head stage and harvested again in December. Effects of treatments were evaluated by seed yield and yield, crude protein, and IVDMD of the forage.

Nitrogen for seed production was more efficient when applied in December, while March was a better time to apply N for forage production. One‐hundred‐one kg/ha was the optimum rate for both purposes. Severe lodging was caused by 134 kg/ha N at both locations. Failure to remove plant residue after seed harvest reduced seed yields the following year from 42 to 45%. These residues average 7.0% crude protein and 52% IVDMD. Forage round baled in the early head averaged 10.9% crude protein and 52% IVDMD. August was the best time to apply N for fall forage production and 101 kg/ha was the optimum rate.
Influence of Conservation‐Tillage Environments on Growth and Productivity of Corn1
Authors: Mock J. J. , Erbach D. C.
Published: July 2010

Research on growth responses of corn (Zea mays L.) to environmental conditions associated with conservation‐tillage systems has not been extensively conducted. Therefore, the objectives of this study were to evaluate effects of various tillage systems (fall moldboard plow, till‐plant, no‐till ridge with and without previous‐crop residue) and early planting on growth and productivity of several corn genotypes (including two heterogeneous breeding populations that were improved for cold tolerance by recurrent selection). The experiment was conducted for 2 years on a loam soil (Typic Hapludoll), and planting dates were 1 Apr. 1974, and 30 Apr. 1975. Conservation‐tillage systems were associated with lower midafternoon soil temperatures (at 5‐cm depth) during the early growing season and more variability in depth of seed placement. Also, seedling and juvenile plant growth, final plant densities, and grain yields were lower in conservation‐tillage systems. These differences were accentuated in the early planting environment of the 1974 experiment. With a relatively normal planting date and equal final plant densities (the not affected by tillage treatment. There was no interaction between tillage method and com genotype. Usually, genotypes with vigorous seedling and juvenile plant growth and high final plant stands produced highest grain yields in all tillage environments. In the central U.S. Corn Belt, therefore, optimum corn grain yields in conservation‐tillage environments will be obtained by the use of planters that assure uniform seed depth and genotypes that display vigorous plant growth and development.
Influence of Plant Stage at Initial Harvest and Height of Regrowth at Cutting on Forage Yield and Quality of Timothy and Orchardgrass1
Authors: Mislevy P. , Washko J. B. , Harrington J. D.
Published: July 2010

The need to obtain the best compromise between yield and quality has been recognized for years. The object of this study was to evaluate the influence of initial harvest at various growth stages and height of regrowth (all cuttings after initial harvest) at cutting on forage yield and quality of ‘Climax’ timothy (Phleum pratense L.) and ‘Pennlate’ orchardgrass (Dactylis glomerata L.). First growth of these grasses was harvested at each of the following stages: (a) transition (changing of apical meristem from vegetative to reproductive growth), (b) boot, and (c) anthesis. Following each initial harvest stage, regrowth was removed throughout the growing season at each of the following plant heights: 10 to 15 cm, 20 to 25 cm, 30 to 36 cm, 41 to 46 cm, and 51 to 56 cm. This field investigation was conducted during 1970 and 1971 on a fine, loamy, mixed, mesic Typic Hapludults (Murrill series) at the Agronomy Research Farm near Rock Springs, Penn.

Delaying the first harvest of timothy and orchardgrass from the transition to anthesis stage resulted in increased yield and estimated total digestible nutrients (TDN). However, total seasonal regrowth, total TDN of regrowth, total digestible protein, and total digestible protein of regrowth decreased significantly (P≤0.05). Allowing plants of both species to attain heights of 20 to 36 cm, with few exceptions, produced highest total and regrowth forage yield, TDN, and digestible protein. However, frequent removal of regrowth, at a plant height of 10 to 15 cm, resulted in significantly (P≤0.05) lower yields and encouraged weed encroachment. These data indicate first harvest forage removal at the transition stage, followed by regrowth removal each time plants attain a height of 20 to 36 cm results in highest production of quality forage as measured by total seasonal regrowth, total TDN of regrowth and total digestible protein.
Fitting Plants Nutritionally to Soils. I. Soybeans1
Authors: Brown J. C. , Jones W. E.
Published: July 2010

Plant species and varieties within species differ in their response to mineral stresses and toxicities. To achieve maximum yields, the plant and the soil must be compatible. In the past, the soil has been changed to fit the plant. In this study, we consider changing the plant to fit the soil, recognizing that plant species and varieties within species have specific nutrient requirements. Ten soybean (Glycine max (L.) Merr.) varieties, representing the germplasm currently used in soybean production in the United States, were subjected to Fe, Zn, and Cu stresses; and Mn and Al toxicities to determine their nutrient requirements or tolerance to mineral elements. Seven soils, which had produced the above nutrient stresses and toxicities in other crops, were used in this study. The soybean varieties showed a differential response to Fe stress by developing severe (‘Forrest’), moderate (‘Hodgson’), or no Fe chlorosis (‘Bragg’). Leaves dropped from Forrest and Bragg soybeans as they developed severe Mn toxicity symptoms. In contrast, ‘Lee’ soybean developed only slight Mn toxicity symptoms. Most soybean varieties grew well when subjected to Zn and Cu stresses, or when grown on Al‐toxic soil. Care should be taken to select the proper soybean variety to be grown on soils where Fe stress or Mn toxicity may be a problem.
Effects of N, P, and K Fertilization on Yield and Quality of Tall Fescue Forage in Winter1
Authors: Balasko J. A.
Published: July 2010

Use of tall fescue (Festuca arundinacea Schreb.) regrowth to extend the grazing season into late fall and winter is becoming increasingly popular in middle‐latitude regions of the USA. Few studies have been reported, however, that deal with factors influencing yield and quality of regrowth forage in winter. A field study was begun in October of 1971 to measure the effects of N, P, and K fertilization on yield and quality of tall fescue regrowth in late fall and winter. Eight fertility regimes were established in each of four replications. These were: 1) N applied at 60 kg/ha in spring and after each of three summer harvests, 2) P applied at 30 kg/ha in spring and in late summer, 3) K applied at 60 kg/ha in spring and in late summer, 4) to 7) the four possible combinations of the above three treatments, and 8) no fertilizer treatment. Forage from all plots was harvested in mid‐May, early July, and mid‐August and then in either mid‐December or mid‐January. In 1971 when the experiment began, all plots were harvested on 9 October rather than mid‐August and then in either mid‐December or mid‐January. Nitrogen fertilization increased yield and concentrations of in vitro digestible dry matter, total nonstructural carbohydrate, K, Mg, and N in the late fall and winter harvested forage and decreased concentrations of dry matter and Ca. Yield and concentration of quality components decreased less in N fertilized forage than in unfertilized and P and K fertilized forage as harvest was delayed from December to January. Phosphorus fertilization had little effect upon yield and quality components. Potassium fertilization decreased both Ca and Mg concentrations. Results suggest that winter forages of sufficient quality to meet most of the nutritional needs of many classes of livestock in mid‐latitude regions of the U.S. may be obtained by manipulating summer and/or fall harvest dates and fertilization rates. Supplementation of regrowth forage with Na and Mg and possibly with P during late winter months would be required.
Components of Developing Soybean Seeds: Oil, Protein, Sugars, Starch, Organic Acids, and Amino Acids1
Authors: Yazdi‐Samadi Bahman , Rinne R. W. , Seif R. D.
Published: July 2010

A thorough chemical analysis on the composition of developing soybean [Glycine max (L.) Merr.] seeds does not appear in the literature. Several investigators have determined protein and oil, while others have determined the carbohydrates. The purpose of this study was to make a thorough analysis of the developing soybean seed, including protein, oil, sugars, starch, organic acids, and amino acids. Soybean seeds from ‘Harosoy 63’ grown in the field and ‘Steele’ grown in the greenhouse were analyzed for these components from 10 days after flowering, at 10‐day intervals, to maturity. These components accounted for 75% of the dry weight of the seed. The remaining dry weight of the seed is in cellulose, crude fiber, and ash. Oil and protein (mg/seed) increased until maturity in Harosoy 63 but leveled off before maturity in Steele. When oil and protein are expressed as percentage dry weight, similar patterns were observed for both cultivars. The sugars glucose, fructose, galactose, sucrose, raffinose, and stachyose were all detected in the soybean seed. Raffinose and stachyose were not detected until 50 and 40 days after flowering in Harosoy 63 and Steele, respectively. Starch reached a maximum value of 14.6 mg/seed in Harosoy 63 and 7.9 mg/seed in Steele at 40 and 30 days after flowering, respectively. Starch then declined sharply in both varieties. The water soluble polysaccharide (mg/seed) fraction showed a steady rise for both varieties throughout the study, but declined as percent of dry weight. The concentration of organic acids was low, with glycolic, succinic, malic, and citric being detected. Citric acid was detected in the greatest quantity. Seventeen amino acids and one unknown component were detected in the amino acid analysis. Of the amino acids detected, seven showed increases while three amino acids as well as the unknown showed decreases. Analysis of variances and standard error of the mean were performed on the data for each trait in each variety using a completely randomized design with specific tests for linear regression over the 70 or 60 days after flowering. In addition, quadratic regression was run for starch. Simple correlation coefficients were also found between all the traits studied and can be obtained upon request.
Soil Crusting and Emergence of Wheat Seedlings1
Authors: Hadas A. , Stibbe E.
Published: July 2010

Soil crusting is usually referred to be the cause of impaired wheat (Triticum aestivum L.) stands in the Negev region of Israel. The soils in this region vary from mixed hyperthermic, typic Ustipsamment soils to fine loamy, mixed hyperthermic typic Ustorthent soils.

The major objective of the work carried out was to estimate and analyze the soil crusting phenomena under field conditions and as a secondary objective to study and analyze wheat seedlings behavior under field and laboratory conditions.

Resistance to penetration of natural soil crusts, measured by penetration from underneath the crust, and its dependence on water content and seed bed preparation methods (disking vs. plowing) were determined. These measurements were collected in a field survey carried out during early winter following the first rain that initiated both wheat germination and a sequence of soil slacking and subsequently, as the soil dried out, crusting. It was found that natural crust resistance to penetration was greater for those formed on disked plots than on plowed plots.

In laboratory trials, using a sandy silt loam (typic ustipsamment) soil, crusts were formed by simulated rainfall (intensity of 10 mm/hour, rainfall applications of 5, 10, and 30 mm in one or two simulated rainstorms). These crusts were found to be less penetrable than the natural ones for the same soil under natural field conditions at the same water contents.

Wheat seedling penetration of soil crusts was evaluated under laboratory conditions, whereas projected penetrability of crusts under field conditions was based on an assumed water potential and subsequent coleoptile thrust in the region of the seedlings. These projected values suggested that crusting in the field may not be the cause for a bad stand, except under extremely adverse conditions. These projections illustrate the urgency of including dynamic considerations of seedling performance in the future studies of small grains germination and emergence under and through crusting soils.
Autumn‐Winter Yield and Quality of Tall Fescue1
Authors: Ocumpaugh William R. , Matches A. G.
Published: July 2010

Stockpiling, an agricultural practice that extends the grazing season into the winter by accumulating growth of standing forage during the growing season, is practiced successfully in numerous regions of the world. The objectives of this 2‐year experiment were to determine, for tall fescue (Festuca arundinacea Schreb.), the effects of spring‐summer defoliation and autumn‐winter environmental conditions on the quantity and quality of forage available during the autumn and winter. Three sets of plots were defoliated during the spring and summer at 4, 8, and 10‐week intervals so that the last defoliation occurred on 9 August of each year. A different subplot of each set of preconditioned plots was then harvested at approximately weekly intervals through November. An additional set of preconditioned plots (8‐week defoliation treatment) were harvested at approximately weekly intervals from the end of November into February. The soil was a fine, montmorillonitic, mesic Udollic Ochraqualfs. More frequent defoliations (4 weeks vs. 8 to 10 weeks) reduced the yield of dry matter in the springsummer period by 30 to 40%, but had no effect on autumn yields. Forage from frequently defoliated plots was of higher quality during the spring and summer than less frequently harvested plots, but frequency of defoliation did not affect the quality of autumn stockpiled fescue and had little effect on autumn yields. Dry matter production in the autumn was directly related to the autumn‐accumulated rainfall (Y = 52.7 + 62.1 X, r = 0.988 for 1971 and Y = —1068 + 163.6 X, r = 0.934 for 1972). Freezing temperatures in early November stopped autumn growth at about 1,000 kg/ha in 1971 and 1,800 kg/ha in 1972. After freezing temperatures, there was a 25 kg/ha/week decrease in harvestable dry matter. The crude protein content decreased steadily throughout the autumn‐winter period, and after growth stopped the rate of decrease averaged about 0.1 percentage unit/week. The in vitro dry matter digestibility of stockpiled fescue remained fairly constant (63 to 68%) from September to early November. After growth was stopped by freezing temperatures in November, digestibility decreased about 1.0 percentage unit/week. The potassium content of the autumn‐grown forage decreased at a linear rate of about 0.1 percentage unit/week throughout most of the autumn‐winter period and, in 1971‐72, decreased to levels considered below the minimum requirements of ruminants.
Smoothing, Interpolation, and Gradients from Limited Data1
Authors: Thomas A. W. , Snyder W. M. , Bruce R. R.
Published: July 2010

Recent publications have presented a variety of techniques for interpolating and smoothing large masses of agronomic and engineering data. This paper, utilizing the technique of sliding polynomials, demonstrates the development of smooth and continuous curves and gradients from very limited experimental data. Procedures for dealing with data in a transformed time and/or space domain are given. Emphasis is placed on utility of the technique and providing sufficient details through examples to allow ready application.
Responses of Corn Earworm Larvae to Maize Silks1
Authors: Widstrom N. W. , Wiseman B. R. , McMillian B. R.
Published: July 2010

Laboratory identification of maize (Zea mays L.) lines which have detrimental silk factors to the corn earworm [Heliothis zea (Boddie)] usually require several silk feedings over a period of 10 to 20 days. Seven maize lines were evaluated in a diallel crossing system for the number of larvae recovered from infested ears after 3 days, to determine the level of genetic variability for antibiosis, and to investigate the feasibility of using 3‐day laboratory measurements to identify genotypes that show antibiosis in the field. Five of these lines were reported as having detrimental silk factors or antibiosis to the corn earworm and two were used as susceptible checks. Genetic differences existed among lines and crosses, but heritability estimates were less than 25%. Measurements of larval antibiosis expression on excised silks in the laboratory were neither consistent nor indicative of the field ratings for larvae recovered. Only Od3 and ZC 2451, of the seven lines tested, had a measurably better level of antibiosis expression than the checks when tested as an inbred. 81‐1 was best in single‐cross combinations. The data suggest that ears of inbreds generally provide a more hostile environment to corn earworm larvae than ears of single crosses. We conclude that the technique of measuring 3‐day larval antibiosis expression does not provide sufficient time for larval antibiosis symptom manifestation and that an effective selection program of maize population improvement will require a longer ear‐larvae association time.
Responses of Greenhouse‐grown Cannabis sativa L. to Nitrogen, Phosphorus, and Potassium1
Authors: Coffman C. B. , Gentner W. A.
Published: July 2010

Growers of illegal Cannabis sativa L. use various cultural practices to maximize crop production. The objective of this study was to evaluate the morphological and biochemical responses of greenhouse grown C. sativa to soil incorporated N, P, and K as they reflect the geographical origin of Cannabis derivatives. Fertilizers were blended with Ap horizon soil from a Gilpin silt loam before placement in 12‐cm pots. NH4NO3‐N was applied at 0, 25, and 125 ppm. Phosphorus and K from super‐phosphate and KCI, respectively, were applied at 0, 50, and 150 ppm. Forty‐five‐day‐old anthesic Cannabis plants were harvested and combined leaf and flower tissues were analyzed for cannabidiol (CBD) and Δ9‐tetrahydrocanna‐binol (Δ9THC). Nine essential elements were also measured in plant tissue. Plant growth, tissue yield, and concentration of CBD and Δ9THC were positively correlated with extractable P2O5 (p < 0.01). Phosphorus concentrations in tissue were similarly related to yield of dry matter and cannabinoid concentrations. Uptake of K was positively correlated with extractable K2O across all treatment levels (r=0.40**), but was negatively correlated with tissue yield (r=‐‐0.36**). Growth and tissue yields were negatively related to total plant N (p< 0.01). Levels of extractable P2O5, Mn, B, and Mg were associated with specific concentration ranges for several plant elements plus Δ9THC. Thus, it was possible to partially characterize a soil by tissue analysis. For example, all of the plants grown on soil with less than 100 ppm of extractable P2O5 contained less than 8,000 ppm Δ9THC. Usefulness of such relationships will be dependent upon extensive evaluation of Cannabis on different soils under various cultural conditions. At this time, the reliability required for determination of origin of Canabis derivatives via chemical analysis does not exist when only essential elements and cannabinoids are considered.
Canopy Characteristics of Narrow‐Row Cotton as Influenced by Plant Density1
Authors: Buxton D. R. , Briggs R. E. , Patterson L. L. , Watkins S. D.
Published: July 2010

The optimum plant density for narrow‐row cotton (Gossypium hirsutum L.) is influenced by the lint yield response to plant density as well as other crop characteristics affecting crop management. This study was conducted to quantify the effect of population density on many of these characteristics. Three experiments were conducted with narrow‐row cotton in population densities ranging from 7.1 to 22.9 plants/m2. In August plants were harvested at ground level and morphological measurements were made. At the end of the growing season lint yield was determined. There were no statistical effects of plant density on lint yield or boll and fiber properties. Population pressure increased plant height when plants were young, while the effect on older plants was inconsistent. The morphological measurements showed (a) each five plants/m2 increase in, plant population decreased the number of mainstem nodes by one, (b) each eight plants/m2 increase in population decreased the number of monopodial branches per plant by one, (c) each 11 plants/m2 increase in population density raised the lowest sympodial branch with a boll by one node. In addition increasing density from about seven to 30 plants/m2 reduced the percentage of bolls supported by monopodial branches in a curvilinear manner from 25 to 0. Increasing plant density, also increased leaf area density, especially in the central portion of the plant canopy. Considered with their probable influence on harvesting efficiency, incidence of diseases and insects, and chemical defoliation, these data should help in predicting the optimum population for narrow‐row cotton. For these studies the optimum appears to be between 10 and 15 plants/m2.
Response of Leaf Water Potential to Pressure Changes at the Root Surface of Corn Plants1
Authors: Nulsen R. A. , Thurtell G. W. , Stevenson K. R.
Published: July 2010

The nature of the hydraulic continuum between the roots and leaves of intact plants requires further study to improve our understanding of the effect of pressure changes. A large pressure chamber was designed to apply hydrostatic pressure to the roots of intact corn (Zea mays L.) plants. The chamber permitted application of up to 6 bars pressure and allowed for in situ watering of the plants. Changes in leaf water potential resulting from changes in pressure applied to the roots were monitored in situ using a thermocouple dewpoint hygrometer. Responses of leaf water potential were consistently between 0.94 and 1.19 times the change in applied pressure, regardless of whether the pressure was being increased or decreased. When pressure was applied to very turgid plants leaf water potential increased until it reached a value equal to the osmotic pressure of expressed xylem sap. Some time after this value was reached water droplets appeared on the leaf surface. The experiments showed that the hydraulic system within intact plants acts as a true continuum in that pressure changes at one end of the system are faithfully, manifested at the other end of the system. If such changes are not observed some additional mechanism must be operating.
Modeling Daily Dry Matter Production of Winter Wheat1
Authors: Hodges Tom , Kanemasu E. T.
Published: July 2010

Applicability of many plant growth models are limited because of the input data requirements. Photosynthesis and respiration equations were developed from meteorological data that could easily be obtained. The single crop parameter required was leaf area index. These equations were developed for winter wheat from measurement of net CO2 exchange with field chambers and an infrared‐gas‐analysis system. Higher gross photosynthesis rates after jointing were attributed to sink enhancement of photosynthesis. Respiration was estimated as a photosynthesis‐dependent growth component and a temperature‐biomass dependent maintenance component. The equations predicted dry matter production that agreed favorably with observed dry matter accumulation.
Grazing Pressures and Animal Performance from Pearl Millet1
Authors: McCartor M. M. , Rouquette F. M.
Published: July 2010

In the Gulf Costal Plain adapted summer annual forages such as pearl millet [Pennisetum typhoides (Burm.) Stapf and C. E. Hubb] are generally higher in energy content than perennial grasses and are capable of producing higher rates of gain. However, practically no data are available which define animal performance at different levels of forage utilization. The lack of definitive data on which to base a grazing program with pearl millet prompted this study which determined liveweight gains of weanling cattle grazing ]pearl millet and evaluated the relationships between gain, forage yield, forage quality, grazing pressure, and profitability.

A hybrid pearl millet ‘Millex 23’ was seeded at the rate of 15 kg/ha on Thenas (Fluvaquentic Eutrochrept; coarse, loamy, mixed, thermic) soil and fertilized with 112 kg/ha each of N, P2O5, and K2O in each of 2 years. Weanling crossbred beef calves were used as tester animals and grazed at stocking rates ranging from 3.73 to 11.35 animals/ha. Liveweight average daily gains (ADG) from 0.27 to 1.01 kg were shown to be a non‐linear function of forage availability and a positive linear function of percent in vitro dry matter disappearance (IVDMD) available forage. Percent IVDMD of available forage varied from 36.29 to 63.57% and was inversely related to length of trial. Neutral detergent fiber values for available forage were negatively correlated with ADG (r= −0.84).

Maximum profitability, expressed as return per ha, was found at intermediate grazing pressure and was dependent upon the magnitude of positive or negative margin between the time of purchase and the time of selling. Maximum profit occurred at greater grazing pressures as the positive margin between selling and purchase price increased.

The most important factor affecting the profitability of grazing pearl millet was the differential between buying and selling price of the cattle. Aside from this factor, which the farmer seldom controls, grazing pressure is the most important determinant of profit. It was concluded that the greatest profit or least loss occurs at medium grazing pressures which, in this study, was approximately 2 kg of available forage per kg of animal liveweight.
Effects of Phosphorus and Potassium on Soybean Nodules and Seed Yield1
Authors: Jones G. D. , Lutz J. A. , Smith T. J.
Published: July 2010

Much of the nutritional research on soybean [Glycine max (L.) Merrill] nodulation has been under greenhouse or laboratory conditions. Additional field data are needed on the influence of nutrients on nodulation and other plant characteristics. The purpose of this investigation was to determine under field conditions the effects of P and K fertilization on number and weight of soybean nodules; the chemical composition of leaves, nodules, and seed; the number of pods per plant; and seed yield.

Annual P rates of 0, 15, 30, and 60 kg/ha were applied with 0 and 112 kg K/ha in one field experiment. In another, annual K rates of 0, 28, 56, and 112 kg/ha were applied with 0 and 60 kg P/ha.

Either P or K applied alone increased the number of nodules per plant and per unit volume of soil. Applied K increased the number of nodules, total and individual weight of nodules, and the number of pods per plant more than P, but increases were largest when both P and K were applied.

Applied K increased the K concentration of nodules, but had little influence on N, P, Ca, Cu, Fe, Mn, and Zn concentration, and decreased Mg; applied P without K increased the P concentration. There was a good correlation between the relative concentrations of P and K in leaves sampled for each of four different sampling dates and the concentration of these elements in the seed. Applied P in excess of 15 kg/ha did not increase soybean yields. Each additional increment of K up to the maximum used (112 kg/ha) resulted in seed yield increases when P was also applied, but with no added P seed yield responses to more than 28 kg K/ha were not significant.

These results showed that application of both P and K individually increased nodulation and pod formation with more response from K than P. Maximum response was obtained when both elements were added. Even though the soil was very low in available P when the experiment was initiated there was no seed yield response to more than 15 kg P/ha. A good yield response was obtained from 28 kg K/ha and to increasing rates of K when 60 kg P/ha was added, thus indicating the higher requirement of soybeans for K than for P.
Clover N‐Fixation Measurement by Total‐N Difference and 15N A‐Values in Lysimeters1
Authors: Williams W. A. , Jones M. B. , Delwiche C. C.
Published: July 2010

Assessment and improvement of N fixation by legumes on annual‐type range is becoming increasingly important in light of the increasing need for energy conservation. A comparison was made of two methods of assessing N fixation: a simple but crude method by measuring the total‐N difference in tops of an N‐fixing legume and a non N‐fixing grass, and a more expensive method using A‐values determined from 15N applications to the same legume and grass species. Subterranean clover (Trifolium subterraneum L.) and soft chess grass (Bromus molis L.) were grown in field lysimeters (69 cm deep by 36 cm diam.) filled with Josephine loam (Typic Haplozerults, fine loamy, mixed mesic) for 3 years. Single (100 and 500 kg/ha) and repeated (100 kg/ha) applications of 15N were made and determinations were made of soil and fertilizer N in the plants, soil, and leachate periodically. The relation between the two methods was strongly linear; fixation (kg/ha) by the A‐value method = 50.1 + 0.852 N fixation by difference (r = 0.98, n = 15). Consequently, previous values cited for N fixation measured by the difference method for winter annual legumes in California may have been underestimated by about 40%.
Soybean Growth and Composition as Influenced by Soil Amendments of Sewage Sludge and Heavy Metals: Field Studies1
Authors: Ham G. E. , Dowdy R. H.
Published: July 2010

The potential influence of sludge‐borne heavy metals on crop growth and the food chain is a major concern with the utilization of municipal sludges in agricultural crop production. The objectives of this field research were to compare soybean plant growth and metal uptake of salt sludge‐borne metals and to determine the partitioning of these heavy metals into the various plant parts.

Soybeans (Glycine max L. Merrill) were grown on soil to which air‐dried, anaerobically digested sludge was applied at rates of 25, 50, and 100 and 200 metric tons/ha. In addition, Zn, Cu, Ni, Pb, Cd, and Cr salts were added individually at levels equivalent to the quantity added in 50 metric tons sludge/ha. Sludge and metal salts were mixed into the top 20 cm of soil by roto‐tilling.

Adding sewage sludge did not significantly influence soybean seed yield. The seed concentration of N, P, K, Zn, and Cd increased, whereas the Fe concentration decreased. Total uptake of elements, other than N, P, K, Ca, Mg, and Fe, was less than 1 kg/ha although the concentration increased significantly in some cases.

Adding Cu salt increased seed yield and Cr salt decreased seed yield; otherwise metal salts did not influence yields. The metal salts of Ni, Zn, and Cd increased their concentration in mature seed.

When mature plants were separated into leaves, stems, husks, or pods and seed, their analyses indicated that Zn was concentrated in the leaves, increasing up to 331 μg Zn/g leaf at the 200 metric ton/ha sludge rate (the Zn concentration in the stems and husks also increased with increasing sludge rates). In contrast, the Zn concentration of the seed leveled off at 100 metric tons sludge/ha. Cadmium and Cu were concentrated in the mature leaf tissue.

Sewage sludge of the type applied in this study could be used as a source of P without yield reductions. These data did not show large increases of sludge‐borne metals in the seed.
Zinc and Cd Accumulation by Corn Inbreds Grown on Sludge Amended Soil1
Authors: Hinesly T. D. , Alexander D. E. , Ziegler E. L. , Barrett G. L.
Published: July 2010

Inbred lines of corn (Zea mays L.) differ in accumulation of Zn and Cd in leaves and grain. The capacity to accumulate Zn and Cd may be under genetic control. Twenty corn inbreds were planted in replicated control and sewage sludge amended, field, lysimeter plots to obtain information on uptake of Zn and Cd in leaves and grain.

Sludge treatments had significantly increased concentrations of both Zn and Cd in the plow layer of soil. Mean total concentrations of Zn ranges from 68 to 454 mg/kg and of Cd from 0.3 to 20.6 mg/kg in the surface of Blount silt loam (Aerie ochraqualf, fine illitic, mesic) soil for control and maximum sludge treated plots, respectively. Concentrations of Zn and Cd in leaves of all inbreds were significantly increased on maximum sludgetreated plots. Zinc concentrations in leaves ranged from 61.8 mg/kg in B77 to 281.8 mg/kg in Oh43 and leaf Cd ranged from 2.5 mg/kg in R805 to 62.9 mg/kg in B37. Concentrations of Zn and Cd in grain of inbreds (except H99 for Zn and H99, Oh545, and R805 for Cd) were increased by higher concentrations of sludge borne metals in soil. Concentrations of Zn in grain varied from 33.8 mg/kg for H99 to 70.0 mg/kg for A619 and Cd varied from 0.08 mg/kg for R805 to 3.87 mg/kg for B37. Inbreds accumulating relatively high levels of Zn in leaf and grain tissue did not always accumulate high concen trations of Cd or vice versa. Mechanisms for controllin absorption of Zn and Cd appeared to be independent each other.
Radiation and Energy Balance of a Trickle‐Irrigated Lemon Grove1
Authors: Ben‐Asher J. , Sammis T. W.
Published: July 2010

Trickle irrigation has become a widely used method. Its primary advantage in arid regions is that it saves water. However, because of its modernity, analytical and experimental results are minute compared to those for conventional irrigation methods. This study was conducted to evaluate the water saving potential and evapotranspiration from a trickle irrigated lemon grove (Citrus limon L. ‘Lisbon’). Detailed measurements of global, reflected, and net radiation and its dissipation above the plant, the unshaded sandy soil, and the area as a whole were made in the spring and summer of 1975. Two sources of radiant energy were observed: net radiation which accounted for 70% of the energy utilized in evapotranspiration and reflected radiation from the unshaded soil accounting for 30%. Experimentally the net radiation and evapotranspiration of the wet complex increased as the average net radiation and the evapotranspiration from the area as a whole decreased and vice versa. On the other hand, evapotranspiration and its ratio to evaporation from a class A pan were smaller than any previously reported values. Therefore, it is suggested that for these two periods the contribution of energy from the dry area to the wet did not reflect a specific disadvantage for trickle irrigation.
Effect of Mowing Height on Leaf Angle, Leaf Number, and Tiller Density of 62 Kentucky Bluegrasses1
Authors: Sheffer K. M. , Watschke T. L. , Duich J. M.
Published: July 2010

Information is needed on the effects of mowing management on Kentucky bluegrass (Poa pratensis L.) morphology. Recently released cultivars have a procumbem growth habit and, therefore, should be more tolerant of close mowing. A study was conducted on 62 Kentucky bluegrasses to determine the effects of mowing height on the leaf angle, leaf number, and tiller density. At each cutting height, the most significant difference among the cultivars was in the angle of the second leaf subtending the bud leaf. In general, when cutting heights were compared, most cultivars were more procumbent when mowed at 1.3 and 2.5 rather than 5.1 cm. Eighteen of the 62 cultivars, however, were not greatly affected by mowing because they varied by less than 6° across the cutting heights. Mowing height affected the leaf number per tiller. Most tillers had more leaves per tiller when mowed at the 2.5 cm height than at the other two heights. The numerical difference was small however, and this effect may only be of minor importance. Leafy cultivars tended to be more upright. As the cutting height decreased, tiller density increased; however, the cultivars varied as to which change in height brought about the most significant effect on tiller production.
Grazing of Grass and Cicer Milkvetch‐Grass Pastures with Yearling Calves1
Authors: Rumburg C. B.
Published: July 2010

Nitrogen fertilization rather than legumes is relied upon for increasing pasture and hay production in the Northern Rocky Mountains because of the difficulty of maintaining stands and the danger of bloat when legumes are used. Cicer milkvetch (Astragalus cicer L.) offers the promise of overcoming both of these objections. This study reports a comparison of N fertilized grass, and cicer milkvetch‐grass pastures (on an Aridic Agriboxolls) when grazed by three classes of cattle over a 3‐year period. Pasture quality was estimated by grazing with two testers each of long‐yearling steers, short‐yearling steers, and short‐yearling heifers which were about 14 and 7‐months old, respectively, at beginning grazing. Pasture production was estimated by addition or removal of stockers to harvest the pasture. Pastures were grazed 10 and rested 30 days in a four‐pasture rotation. The two pasture treatments were similar in average daily gain (0.99 kg/day); however, fertilized grass pastures produced a higher yield of digestible energy (15,000) than cicer milkvetch‐grass (13,000 Meal/ha), which resulted in live weight gains of 514 and 434 kg/ha, respectively. The older and heavier long yearlings consistently gained weight more rapidly (1.14 kg/day) than younger and lighter short‐yearling cattle (0.92 kg/day), but short yearlings produced more gain per hectare. Cicer milkvetch‐grass pastures may be an alternative for N fertilized grass pastures depending upon relative cost of N. The inclusion of cicer milkvetch added nothing to forage quality, and was 14% less productive than grass pastures fertilized with 1.12 kg N/ha.
Effect of N Depth and Application Rate on Yield, Protein Content, and Quality of Winter Wheat1
Authors: Cochran V. L. , Warner R. L. , Papendick R. I.
Published: July 2010

Providing a supply of N to winter wheat (Triticum aestivum L.) after heading may offer a means for increasing grain protein content without the need to apply fertilizer in excess of requirements for maximum yield for fhis procedure to be practical in the winter rainfall climate of the Pacific Northwest, the N at grain fill must be deep in the profile, where water is being absorbed. An experiment was conducted on Mesic Calciorthidic Hap. loxerolls (Ritzville silt loam) in dryland eastern Washington to determine the effect of N depth and application rate on yield, grain protein content, and flour quality of ‘Nugaines’ and ‘Wanser,’ a soft white and a hard red winter wheat, respectively. Nitrogen was placed shallow (less than 50 cm depth) at 55 or 110 kg/ha or deep (60 t0 120 cm depth or deeper) at 55, 110, and 220 kg/ha. Deep placement was achieved by applying Ca(NO3)2, irrigating with 12 cm of water prior to fall planting, and relying on deeper movement from overwinter precipitation. For the shallow placement, the N was applied in late winter of the crop year. All plots received a broadcast application of 35 kg N/ha as (NH4)2SO4 before planting. Maximum grain yields were approached with 55 kg N/ha, and excess N remained in the profile at the higher application rates for both placements. Depth of N did not affect grain yield or protein content when the shallow soil layers were moist much of the time during spring and early summer from above‐normal precipitation. However, with more typical conditions where the upper 1 m of soil was relatively dry at heading, yield and grain protein content of Nugaines wheat and grain protein content of Wanser wheat was increased significantly from deep N placement. Also, deep placement of 55 kg N/ha caused higher gain protein levels than with 110 kg N/ha placed shallow. For the hard red wheat, only flour of grain from the deep‐placed N exceeded minimum bread‐baking standards. All soft white wheat treatments except the 220 kg N/ha application exceeded minimum pastry quality standards, but the highest quality was with the shallow N placement. Thus, in the low precipitation areas of the Northwest, deep N placement may improve quality of hard winter wheat; but it may adversely affect the quality of soft white wheat.