bluuebunny/crossref_metadata_2025 huggingface dataset:
Orientation of Leaves of Winter Wheat Planted in North‐South or East‐West Rows1
Authors: Kirkham M. B.
Published: July 2010

The objective of the present experiment was to determine if, and to what extent, leaves of winter wheat (Triticum aestivum L. em. Thell.), oriented in two row directions, received different amounts of light. At times distributed over two growing seasons, including fall, winter, and spring months, values of I/IO (intensity of received direct‐beam radiation to incident direct‐beam radiation) were calculated from solar‐noon sun angles for leaves of winter wheat (cv. ‘Osage’), planted in north‐south (NS) and east‐west (EW) rows. Another objective of this research was to determine leaf disposition, area, width, and length, regardless of light intensity received, for fall, winter, and spring months. In addition, climatic data were collected.

Results for the winter growth period were significant. The winter results showed that I/IO values for leaves in NS and EW rows differed markedly during the slow‐growing winter season. Furthermore, on cold, windy days, it was found that leaves in NS rows were prostrate and leaves in EW rows were erect, apparently because the plants in the EW rows were protected in the winter from the prevailing northerly winds by ridges made at planting. The leaf measurements showed that leaves in EW rows were long and narrow and leaves in NS rows were short and wide. Also, plants in NS and EW rows had most leaves pointing southerly and easterly, respectively, for all seasons; fewest leaves pointed northeasterly in both NS and EW rows. There were more living leaves in NS rows than in EW rows. The leaf measurements and I/IO calculations showed that, during winter, the leaves in EW rows, which were generally erect and not prostrate (horizontal), were oriented in many directions and had the full range of I/IO values (range: 0 to 1.00), while leaves in NS rows, which were often not erect, but prostrate, despite wind, had a range of values of I/IO from 0.18 to 0.76, independent of leaf direction.
Sunflower Nutrient Uptake, Growth, and Yield as Affected by Nitrogen or Manure, and Plant Population1
Authors: Mathers A. C. , Stewart B. A.
Published: July 2010

Sunflower (Helianthus annuus L.) is a new crop in the Southern High Plains. It was grown on Pullman clay loam (Torrertic Paleustoll) in an experiment designed to determine the effects of N, plant population, and row spacing on growth, yield, and nutrient uptake. Fertility treatments were 0, 84, and 168 kg N/ha and residue from three annual applications of 22 and 67 metric tons of manure/ha (wet wt.). Populations of 37, 62, and 99 thousand plants/ha were grown in a bed‐furrow irrigation system in two row spacings (one and two rows 30 cm apart) per bed. Beds were spaced 1 m apart. The crop was irrigated to provide adequate water. Beginning about 7 weeks after planting, samples were taken at 2‐week intervals for dry matter yields and chemical analyses. Seed and oil yields were taken at maturity.

In 1975, the seed yield on the unfertilized treatment was 1,950 kg/ha, whereas all other treatments produced similar yields averaging 2,850 kg/ha. In 1976, yields were similar on the unfertilized and inorganic N treatments (avg. 2,000 kg/ha) and similar on the manure treatments (avg. 2,330 kg/ha). Lower sunflower yield in 1976 than in 1975 is attributed to higher temperatures during the seed filling period in 1976. Both N fertilizer and manure reduced oil percentage in seed. Even though statistically significant effects were found in 1975, yields were not affected to a large degree by differential row spacings and plant population treatments. Dry matter and nutrient yield curves showed that adequately fertilized sunflower produced about 10 metric tons of dry matter/ha containing 200 kg N, 35 kg P, 450 kg K, 180 kg Ca, and 45 kg Mg/ha.

The 84 kg N/ha rate supplied sufficient N for maximum sunflower yields. Apparently, manure supplied some needed element or condition not supplied by inorganic N. That factor was not identified. Plant populations from 37 to 99 thousand/ha gave satisfactory yields.
Austrian Winter and Spring Peas as Green Manure Crops in Northern Idaho1
Authors: Auld D. L. , Bettis B. L. , Dial M. J. , Murray G. A.
Published: July 2010

The increasing cost of N fertilizers has caused a renewed interest in the utilization of Austrian winter peas [Pisum sativum ssp. arvense (L.) Poir] as a green manure crop. From 1977 to 1980 field experiments on a palouse silt loam (fine, montmorillonitic, mesic Xeric Argialboll) were conducted in northern Idaho to determine the planting date, harvest date, and cultivar of Austrian winter peas that produced the maximum yield of organic matter (OM) and N in the vines. Organic matter yield was determined by harvesting and weighing the vines from four‐row plots (1.3 m2). A 1‐kg sample from each plot was dried and wet weights were adjusted to an oven dry basis. Vine N was determined using either micro‐Kjeldahl or a Technicon Autoanalyzer II System.

Austrian winter peas seeded in early September produced the highest yields of OM and vine N. Delaying seeding until early October reduced OM production and vine N by over 50% at both locations. Vine N was increased only 28 kg/ha by delaying harvest from early bloom to late pod filling but OM yield was increased by 4.9 metric tons/ha.

‘Melrose’ produced the most OM (13.9 metric tons/ha) and vine N (321 kg/ha) of the five winter pea lines evaluated. All of the lines accumulated in excess of 250 kg of vine N/ha averaged over both test years.

The four long‐vined Austrian winter pea lines yielded an average of 13.0 metric tons of OM/ha when fall planted but only 6.9 metric tons/ha when planted in the spring. Six spring pea cultivars (P. sativum L.) averaged 12.1 metric tons/ha but late maturity would have prevented plow‐down under dryland conditions.

In northern Idaho, Austrian winter peas could produce in excess of 10 metric tons/ha of OM which would contain a minimum of 175 kg/ha of vine N. The inclusion of Austrian winter peas as a green manure crop in crop rotations could have a significant impact on the total N budget of the soils in this region.
Mulching and Green Manure Applications for Continuous Crop Production in the Amazon Basin1
Authors: Wade M. K. , Sanchez P. A.
Published: July 2010

Kudzu (Pueraria phaseoloides) and guineagrass (Panicum maximum) cuttings were each used as mulch or incorporated as green manures under three fertilizer treatments in a Typic Paleudult soil at Yurimaguas, Peru to evaluate their potential as organic additions for continuous crop production in the Amazon Basin. Mulching with guineagrass decreased topsoil temperatures by 5 C prior to the establishment of a crop canopy, conserved soil moisture in the top 5 cm during dry weather, prevented surface crusting and decreased weed growth. Mulching had. little effect in increasing the availability of N, K, Ca, and Mg. The use of mulches without chemical inputs produced an average of 75% of the crop yields achieved with completely fertilized, bare plots. For five consecutive crops, incorporating kudzu at the rate of 8 tons fresh material/ha/crop produced yields which were 90% of the crops receiving complete inorganic fertilization and liming. Guineagrass incorporation was also beneficial but generally less so than kudzu. The beneficial effects of incorporating kudzu as green manure were associated with the amounts of N, P, K, Ca, and Mg released from the decomposing material, decreased AI saturation, and possibly enhanced nutrient accumulation due to less moisture stress and lower bulk density. No response to organic additions were found when recommended amounts of lime and fertilizers were supplied.
Phosphorus Requirements of Alfalfa‐Smooth Bromegrass‐Orchardgrass and Reed Canarygrass Pastures under Two Grazing Pressures1
Authors: Mallarino A. P. , Wedin W. F. , Voss R. D. , West C. P.
Published: July 2010

Most recommendations for P fertilization of pastures are based on data from small plots from which the herbage is clipped and removed. This may overestimate the sward growth responses to fertilizer P because of the absence of trampling and nutrient cycling by grazing animals. In a beef‐steer grazing study conducted on Aquic Argiudoll‐Typic Argiaquoll soils in Iowa we determined the effect of fertilizer P applied to two pasture types under two grazing pressures. Pasture types were: (1) ‘Pioneer 520’ alfalfa (Medicago sativa L.)‐‘Baylor’ smooth bromegrass (Bromus inermis Leyss.)‐‘Napier’ orchardgrass (Dactylis glomerata L.), and (2) ‘Rise’ reed canarygrass (Phalaris arundinacea L.). The alfalfa‐grass pastures received no N fertilizer, whereas reed canarygrass pastures received 180 kg ha−1 year−1 of N. The 1.32‐ha pasture units were divided into three 0.44‐ha rotational grazing strips, upon which either 0, 20, or 40 kg ha−1 of P was topdressed in the spring of 1979. In 1980, three small plots were designated in each of the 0.44‐ha rotation strips to which the same three P treatments were randomly assigned. The grazing pressures were at 8 and 11 kg of available dry matter/steer‐day. No significant effects resulting from grazing pressure were detected for dry matter yield, plant P, or soil‐test P values. Herbage dry matter yield in 1979 was not influenced by P rate; however, in 1980, both pasture types exhibited a positive linear response to P where no P had been applied in 1979. In rotation strips that had received no P fertilizer in 1979, alfalfa‐grass dry matter yields in 1980 exhibited a quadratic relationship to soil‐test P levels, i.e., yield optimum at 25 ppm of soil‐test P (Bray 1). Reed canarygrass dry matter yields in 1980 exhibited a linear relationship to soil‐test P levels with an apparent leveling off of yield above soil‐test P of 20 ppm. We concluded that yield response to P topdressing is improbable at soil‐test P levels at or above 22 to 25 ppm (Bray 1) for alfalfa‐grass and 15 to 20 ppm for reed canarygrass pastures.
Growth and Seed Yield Characteristics of Birdsfoot Trefoil1
Authors: McGraw Robert L. , Beuselinck P. R.
Published: July 2010

Difficulty in harvesting sufficient quantities of seed is a major factor limiting use and production of birdsfoot trefoil (Lotus corniculatus L.). A growth analysis of ‘Norcen’, ‘Viking’, and ‘Empire’ birdsfoot trefoil was conducted in the field at Roseau, Minn. in 1980 and 1981 to investigate physiological and morphological characteristics which limit seed yield potential. The soil was a Glyndon silt loam (coarse‐silty, calcareous Aeric Calciaquoll). Two major factors were largely responsible for low seed production: (1) low partitioning of assimilates to seed yield and (2) indeterminate flowering habit accompanied by dehiscent pods. Plants partitioned an average of about 40% of available assimilates to reproductive growth. Of the assimilates partitioned to reproductive growth, only about 30% became seed; the rest was distributed in peduncle, pedicel, and pod walls. Thus, only 12% of available assimilates was partitioned to seed. The stem component was the major sink for accumulation of dry matter until 2 weeks before final sampling when the umbels became the major sink. Plants flowered and new umbels were produced over a long period; consequently, umbel maturity varied widely on a single plant. Many umbels were still immature when the first dehisced pods were observed. At maximum pod maturity, about one‐third of the umbels contained either dehisced or immature pods. Genetic improvement or improved cultural or chemical methods that would increase partitioning to seed, produce a more determinate growth habit, or increase dehiscence resistance should help increase seed yields in birdsfoot trefoil.
Soil Contamination and Elemental Concentrations of Forages in Relation to Grass Tetany1
Authors: Cherney J. H. , Robinson D. L. , Kappel L. C. , Hembry F. G. , Ingraham R. H.
Published: July 2010

Relationships among soil contamination of forages, elemental concentrations in forages samples, and grass tetany are not clear. Our objectives were to determine the extent and seasonal variation of soil contamination on annual ryegrass (Lolium multiflorum Lam.) samples, and to relate the contamination to various indicators of grass tetany. Seasonal variation of soil ingestion by grazing beef cattle was also investigated. Field experiments were conducted on a Tensas silty clay soil (fine, montmorillonitic, thermic Vertic Ochraqualf). Highly significant positive correlations were obtained among AI, Fe, and Ti concentrations within forage and rumen content samples. Concentrations of these elements occurred in the same ratios as in digested soil. Soil contamination during peak periods averaged approximately 70 g/kg in forage samples and 95 g/kg in rumen content samples. A washing procedure was ineffective in removing all of the soil contamination from forage samples. Forage samples taken in areas protected from grazing animals showed no apparent excessive uptake of AI by the plants at any time during the grazing season. The amount of soil contamination on forage plants and the amount of soil ingested by grazing animals increased with increased grazing pressure, decreased forage production, and saturated surface soils. A rapid decline in forage Mg and Ca concentrations may have been a major factor in the Occurrence of grass tetany, but was not associated with highest levels of soil contamination.
Sunflower Germination under Simulated Drought Stress1
Authors: Somers D. A. , Ullrich S. E. , Ramsay M. F.
Published: July 2010

Sunflower (Helianthus annuus L.) production is occurring and expanding under dryland conditions in many semiarid regions of the world. In some of these areas moisture stress may limit stand establishment. Germination of sunflower seeds in aqueous solutions of polyethylene glycol 20,000 (PEG) was evaluated as a screening technique for the selection of sunflower cultivars able to emerge under low soil moisture conditions. Germination of seed from four sunflower cultivars was determined at 0, −6, −11, −15, and −21 bars osmotic potential. No significant differences were observed among cultivars at 0 and −6 bars. Germination of three cultivars was significantly reduced at −11 bars. The germination of all cultivars was further reduced at −15 bars and completely inhibited at −21 bars. Emergence of the same cultivars from Palouse silt loam soil (fine‐silty, mixed, mesic Pachic Ultic Haploxeroll) adjusted to −4, −6, −7, −11, and −14 bars matric potential was not significantly different at −4, −6, and −7 bars for three cultivars, while one cultivar exhibited reduced emergence at all these matric potentials. The emergence of the seed of all cultivars was reduced at −11 bars and completely inhibited at −14 bars. Data from each analysis were pooled over all cultivars at each water potential for comparison of the two methods. Emergence from the soil was reduced at higher water potentials than germination in PEG solutions. However, the relationships of emergence to matric potential and germination to osmotic potential were similar indicating that PEG solutions may be useful in screening sunflower cultivars for improved emergence during moisture stress.
Retrev: a Software System for Managing Comprehensive Crop Survey1
Authors: Grube M. , Steinhorst R. K. , Wiese M. V.
Published: July 2010

Analyses of crop performance over a defined production area require the identification and quantification of yield determining variables coupled with measurements of yield. Because of the inherent complexity of most crop production ecosystems, analyses of crop performance usually necessitate the collection and interpretation of large amounts of data describing yield and yield constraints and proponents. In this light, a software system called RETREV was developed to manage comprehensive crop survey data and assist with yield loss assessments. RETREV flexibly files survey data by crop, year, sample site, sample date, and variable name. It provides definition, indexing, storage, retrieval, and subsetting of data sets and accommodates single and multiple measurements of discrete (alphanumeric) and continuous variables. The FORTRAN program also preprocesses data for use in subsequent programs or analysis packages to generate univariate and multivariate yield analyses, crop yield models, and written reports. RETREV currently is used in an evaluation of regional yields of peas (Pisum sativum L.), wheat (Triticum aestivum L.), and sugarbeets (Beta vulgaris L.) relative to pest, weather, soil, and management data.
Basic Cation Saturation Ratios as a Basis for Fertilizing and Liming Agronomic Crops. II. Field Studies1
Authors: McLean E. O. , Hartwig R. C. , Eckert D. J. , Triplett G. B.
Published: July 2010

A field experiment was conducted over a period of six cropping years to determine the relative merits of basic cation saturation ratio (BCSR) and of sufficiency level of available nutrients (SLAN) as bases for a p plying lime (Ca and Mg) and fertilizer K for crops. The study involved an acid Loudonville silt loam soil (Ulfic Hapludalf, fine‐loamy, mixed, mesic) which had been adjusted to 3 pH (Ca), 3 Mg, and 2 K levels, in all combinations. The sequentially grown crops were: corn (Zea mays L.), corn, soybeans (Glycine max L. Merr.), wheat (Triticum aestivum L.), alfalfa (Medicago sativa L.), and alfalfa. The treatment variables for pH were: 5.0, 6.0, and 6.5; for percent Mg saturation of soil CEC were: 4, 6, and 10; and for percent K saturation of CEC were 2.4 and 4.3. Both yields and crop compositions were measured. The treatment variables resulted in an average soil Ca/Mg ratio range of 2.3 to 26.8 and an average soil Mg/K ratio range of 0.6 to 3.6. Direct correlation or association of crop yields with basic cation saturation ratios (BCSR) were quite low. Also, the treatments producing the five highest yields for each crop gave rather wide ranges in both Ca/Mg and Mg/K ratios which were to a large extent also common to those ratios associated with the five lowest yielding treatments. Thus, finding no evidence to support the validity of the BCSR concept as a basis for providing maximum crop yield conditions, the direct response of the crops to the basic nutrient cations (SLAN) concept was examined. Although yield responses to increased levels of the cations were not obtained in all cases, the results obtained were reasonable; and compositions of Ca, Mg, and K were in almost all cases increased as the levels of the respective cations were increased. The results strongly suggest that for maximum crop yields, emphasis should be placed on providing sufficient, but nonexcessive levels of each basic cation rather than attempting to attain a favorable BCSR which evidently does not exist.
Nitrogen Fixing Activity of Water Stressed Siratro1
Authors: Ismaili Mohammed , Briske D. D. , Weaver R. W.
Published: July 2010

Siratro [Macroptilium atropurpureum (DC.) Urb. cv. siratro] is grown in tropical and subtropical environments characterized by frequent periods of drought and is dependent on N2 fixation for its N. These investigations were conducted to relate leaf and nodule water potentials to N2 (C2H2) fixing activity and determine the capability of nodules to recover N2 (C2H2) fixing activity following water stress. Plants were grown in pots containing vermiculite under controlled environment conditions. Forty‐two days after planting four water treatments were imposed by withholding water for increasing periods of time. Water treatments created a decrease in leaf and nodule water potentials corresponding to the period of time water was withheld. However, when water potentials decreased below −1.5 MPa, nodule water potentials became more negative than leaf water potentials. A similar decrease in water potential suppressed growth of both nodules and shoots. In the longer duration, water withholding treatments nodule and shoot weights decreased as a result of nodule sloughing and leaf shedding. All water withholding treatments reduced the rate of N2 (C2H2) fixing activity.

Nodules with water potentials of −1.5 MPa or greater were able to regain much of their N2 (C2H2) fixing activity within 2 d following rewatering. The specific activity of nodules surviving the most severe level of water stress (−1.9 MPa) were only about 60 % as active as the control 6 d following rewatering. Nodules were irreversibly inactivated by water stress more severe than −3.0 MPa but in approximately 12 d following rewatering new nodules developed. Regrowth of siratro following water stress may be delayed while the capacity for N2 fixation recovers.
Ammonium Uptake by Wheat Varieties Differing in Al Tolerance1
Authors: Fleming A. L.
Published: July 2010

Previous studies have indicated that wheat (Triticum aestivum L.) cultivars absorbed nutrients more efficiently and induced a higher pH in the root zone than Al sensitive cultivars. In many of these studies, plants were screened on acid soils fertilized with NH4NO3 or in nutrient solutions containing up to 15% NH+4‐N. The research reported in this paper was conducted to determine the impact of NH+4‐N nutrition on the response of wheat varieties to Al and to define the relationship between plant‐induced pH changes in nutrient solutions and the utilization of NH+4‐N. ‘Atlas’ and ‘Redcoat’ wheat were grown in nutrient solutions that contained variable ratios of NO‐3‐N and NH+4‐N (100/0, 90/10, 80/20, and 70/30) with or without Al. In the absence of NH+4‐N and Al, both Atlas 66 (Al‐tolerant) and Redcoat (Al‐sensitive) wheats increased the pH of the nutrient solution at equal rates. With NH+4‐N (10 to 30% of the total N), Atlas 66 achieved a higher equilibrium pH than Redcoat. The Al treatments with NH+4‐N inhibited the uptake of NO‐3‐N, reduced the rate of pH increase and injured Redcoat more than Atlas. Aluminum injury was intensified by increasing the concentration of NH+4‐N in the solution. It was concluded that NH+4‐N uptake by Redcoat, with the coincident pH decrease and interference with NO‐3‐N metabolism, was a major determinent of sensitivity to Al.
Estimating Symbolic Nitrogen Fixation by Trifolium subterraneum L. during Regrowth1
Authors: Phillips Donald A. , Jones Milton B. , Center D. Michael , Vaughn Charles E.
Published: July 2010

Two complementary experiments were conducted to determine whether symbiotic N2 fixation could be estimated by applying 15N technologies to Trifolium subterraneum L. organs that would remain after various grazing treatments. Both experiments analyzed monocultures and 50:50 mixtures of T. subterraneum L. and Bromus mollis L. planted at 2000 seeds/m2 in 15N‐supplemented Laughlin loam, a member of the fine‐loamy, mixed, mesic family of Ultic Haploxerolls. In one study, lysimeters were monitored through two growing seasons, while plant shoots were clipped once or three times during each growing season. In the other study, plants were grown in unleached pods under glasshouse conditions with various clipping treatments. Symbiotic N2 fixation was estimated by the 15N‐dilution method and compared with the value determined from a total N‐difference method that included leached N changes in the case of lysimeters. Clipping treatments had similar effects on both estimates of N2 fixation in clover monocultures when shoot 15N concentrations at the final harvest were used for the 15N‐dilution calculations. Shoot 15N values also produced estimates similar to the N‐difTerence method in clover‐grass mixtures harvested only at the end of the season, but such 15N‐dilution calculations consistently underestimated N2 fixation relative to the N‐difference method for clover‐grass mixtures clipped more than once. Using root or crown 15N concentrations to estimate N2‐fixation produced lower values than the N‐difference method in all clipping regimes and species compositions. A major difficulty in using either the 15N‐dilution technique or the N‐difference method to estimate N2 fixation in pastoral systems is that a measure of total reduced N harvested in the legume is required. This requirement can be met in clipping trials but not in continuous grazing studies. Efforts to calculate N2‐derived N in forage from 15N concentration in shoots, crowns, or roots remaining after previous clippings and reduced N in herbage of unclipped plants, a realistic technique for grazing studies, were inaccurate relative to the N‐difference method in this study. Thus one must conclude that although 15N technologies can estimate N2 fixation with the same relative accuracy as the N‐difference method in unclipped plants, neither technique can be applied with certainty when undetermined amounts of forage are removed by animals.
Response of Dry Beans to Daily Deficit Sprinkler Irrigation1
Authors: Miller D. E. , Burke D. W.
Published: July 2010

Dry beans (Phaseolus vulgaris L.) are an important irrigated crop in the Pacific Northwest, but no information is available as to their water requirements under high‐frequency sprinkler irrigation. The present study was conducted to evaluate the response of dry beans to variable amounts of water applied daily by sprinkler, as affected by soil water‐holding capacity. Studies were conducted on a Warden loam (coarse‐silty, mixed, mesic Xerollic Camborthids) near Prosser, Wash., and on a Quincy sand to loamy sand (mixed, mesic Xeric Torripsamments) near Paterson, Wash. Beans were irrigated uniformly by solid‐set sprinklers until near the time of full canopy, when irrigation variables were initiated and continued until harvest. At harvest yields of vines, clean beans, and seed weight were determined. On the loam soil yields were not reduced when daily sprinkler irrigation was much less than estimated evapotranspiration (ET). It was concluded that no more than 10 to 15 cm of water need be applied from full cover until harvest. On the sandy soil, yields increased with water applied up to the equivalent of nearly 100% estimated ET. On the sandy soil, with limited water holding capacity, it is not possible to reduce irrigation to much below estimated ET without loss in yield.
Relationships Between Leaf Water Potential, Canopy Temperature, and Evapotranspiration in Irrigated and NonIrrigated Alfalfa
Authors: Sharatt B. S. , Reicosky D. C. , Idso S. B. , Baker D. G.
Published: July 2010

A prerequisite to exploiting potential production of any crop is to accumulate a knowledge of plant responses, whether the response is to climate, fertilizer, or water. This paper describes a study on a Waukegan silt loam soil (fine‐silty over sandy or sandy skeletal, mixed, mesic Typic Hapludolls) where stress differences between irrigated and nonirrigated alfalfa (Medicago sativa L.) were evaluated during the daytime in order to expand the limited information available on alfalfa water relations. Canopy temperature (CT), evapotranspiration (ET), and leaf water potential (Χ1 served as indicators of stress and were measured using an infrared thermometer, portable chamber, and pressure chamber, respectively. Canopy temperature and ET did not differ appreciably between irrigated and nonirrigated alfalfa in early morning, but after 0900 h and throughout the afternoon nonirrigated alfalfa had a higher CT and lower ET. Leaf water potential of nonirrigated alfalfa was consistently lower during the day. The maximum difference in CT, ET, and Ψ1 between irrigated and nonirrigated alfalfa occurred at 1500 h where they equalled 2°C, 0.2 mm/h, and 0.7 MPa, respectively. These stress differences reflected the differences in the plant available water of 280 and 60 mm (corresponding to 117 and 25% of extractable water) in the 1.83‐m soil profile of the irrigated and nonirrigated plots, respectively. Nonirrigated alfalfa Ψ declined at a faster rate as the peak stress period (1500 h) was approached; however, after this period a faster rehydration was observed for this treatment, as indicated by the relationship between and ET. Despite the faster rehydration of nonirrigated alfalfa, the degree of hysteresis was greater for this treatment than for irrigated alfalfa. The relationship between CT and ET indicated a larger rate of change in CT prior to the peak stress period for nonirrigated as compared to irrigated alfalfa. After this time and until 1700 h, CT remained constant as ET decreased, indicating a decreasing ratio between ET and net radiation and thus greater restrictions on water movement through the plant, a direct cause of the hysteresis observed.
Effects of Wastewater Irrigation and Plant and Row Spacing on Soybean Yield and Development1
Authors: Cordonnier M. J. , Johnston T. J.
Published: July 2010

Considerable research has demonstrated that soybean [Glycine max (L.) Merr.] yields can be increased with the addition of supplemental water during reproductive stages, but little information is available concerning the use of municipal wastewater as the water source. Variables included in this field study were: three water regimes‐municipal wastewater, well water and no water; two row spacings‐51 and 76 cm; two in‐row spacings‐20 and 32 plants/m and two cultivars‐Nebsoy and Harcor. Soybeans planted on a Miami silt loam soil (fine‐loamy, mixed, mesic Typic Hapludalf) received a total of 9.8 cm of wastewater or well water as overhead spray irrigation in 1979 and 9.4 cm in 1980. Data were collected on seed yield, agronomic characteristics, dry matter production, leaf photosynthesis, and leaf chemical analysis. Seed yields were significantly different for water treatments in 1979 with 2,430, 2,580, and 2,790 kg ha−1 for no water, well water and wastewater, respectively. Yields generally increased as plant population increased with the greatest yield for both cultivars occurring at the highest plant population (645,500 plants ha−1). Irrigated plants were 4 to 5 cm taller, matured 5 to 6 days later, had larger seeds and lodge slightly more than nonirrigated plants. The two cultivars responded differently to the wastewater, with Harcor exhibiting a better response than Nebsoy. The 1980 growing season was wetter than normal and there was little or no yield response to irrigation. Under the conditions of soil type, climate and wastewater quality found during this experiment, wastewater was generally superior to well water in increasing yields.
The Effect of Root Temperature and NO−3/NH+4 Ratio on Strawberry Plants. I. Growth, Flowering, and Root Development1
Authors: Ganmore‐Neumann Ruth , Kafkafi U.
Published: July 2010

The purpose of this work was to study the effect of various NO−3/NH+4 ratios in the nutrient solution at various root temperatures on strawberry (Fragaria ananassa) plants. The results could lead to a suitable NO−3/NH+4 ratio of the fertilizer solution to be applied in field‐grown strawberry plants in different seasons on sandy soils.3 Strawberry plants were selected for uniformity and transferred individually to a 1 L container through which the nutrient solution was flushed at a rate of 1 L/h. The total N concentration was 7 me/L. Five ratios of NO−3/NH+4, 7/0, 5/2, 3.5/3.5, 2/5, and 0/7, respectively, were used, each at four root temperatures (10, 17, 25, and 32°C). Constant NO−3/NH+4 ratio, constant total nutrient concentration, and constant pH (6.2) were maintained for 8 weeks. There is a general decline in root growth with increasing root temperature when a single source of N is supplied. This decrease is followed with a decrease in the sugar concentration of the roots. At 32°C root temperature gradual increase in the NH+4 fraction in the nutrient solution is followed by gradual deterioration of the plants to a complete death at 100% NH+4. This death is related to the depletion of sugars and possible shortage of oxygen in the root cells due to NH+4 metabolism in the root.
Response of Several Genetic Sources of Corn to Acidic Soil1
Authors: Sherchan Kishor , Ellis Roscoe , Whitney David A. , Wassom Clyde E.
Published: July 2010

Plants differ in their ability to take up nutrients. Developing genotypes efficient in utilizing nutrients from acid or low nutrient soils would aid in growing crops successfully when mineral supplementation is not feasible. This study was conducted in the greenhouse using mine spoil soil of initial pH 3.9 with variables of genetic sources of corn (Zea mays L.) and lime rates. Genetic source variability was more pronounced under stress conditions (low pH) than under nonstress conditions. The genetic sources PI270083, PI270080, and Va17 showed higher tolerance to acidic conditions than others. Inbred C105, highly susceptible to low pH, showed the most visual root damage as well as the lowest relative dry matter yield. Aluminum concentration in the plant tissue did not vary significantly with lime level; however, exchangeable Al in the soil decreased drastically as the level of lime application increased. Manganese in the plant tissue and in the soil (DTPA extractable) both decreased with increased lime rate. Dry matter yield decreased significantly at 16 500 kg ha−1 of lime compared with 8000 kg ha−1. Phosphorus concentration decreased in the plant as well as in the soil (Bray P‐1 extractable) at 16 500 kg ha−1 lime, which could have been a factor in reduced yield. Genetic source by lime interaction was significant for Ca, Mg, Al, and Mn concentration indicating that selection under different pH levels would be productive.
Foxtail Barley Heading, Yield, and Quality as Influenced by Growth Regulators and a Desiccant1
Authors: White Larry M.
Published: July 2010

Foxtail barley (Hordeum jubatumL.) mixed with other forages harvested after heading or accumulated material bears awns that mechanically injure livestock and game animals upon consumption. This study examines the use of several growth regulators and a desiccant on supression of heading of foxtail barley and subsequent changes in forage yield and quality. During 1979 and 1981, stands of foxtail barley on two subirrigated, lowland sites (Ustic Torrifluvent and Typic Ustifluvent soils) were treated at different stages with growth regulators, at different rates, and with a desiccant. Effects of treatments were determined on number of heads, dry matter (DM) yield, estimated in vivo DM digestibility, and crude protein concentration of the foxtail barley forage. Treatments (kg ai. ha−1) were as follows: metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl) acetamide] at 2.8, 5.6, and 8.4; mefluidide [N‐(2,4‐dimethyl‐5‐[[(trifluoromethyl)‐sulfonyl]amino]phenyl)a cetamide] at 0.28,0.56, and 0.84; maleic hydrazide (MH) [1,2dihydro‐3,6‐pyridazinedione] alone at 4.5; MH at 3.36 with chlorflurenol [methyl‐2‐chloro‐9‐hydroxyfluorene‐9‐carboxylate] at 1.12; and paraquat [1,1'dimethyl‐4,4'‐bipyridinum dichloride] at 0.9 with 0.5% (v/v) X‐77 (spreader‐activator). Paraquat and MH plus chlorflurenol were the only chemicals that consistently reduced heading of foxtail barley (83 to 98%) both years. Maleic hydrazide plus chlorflurenol also consistently reduced heading when applied either 1 or 3 weeks after the first floral primordia developed. Reducing heading more than 90% reduced DM yield more than 50% the 1st year and 80% the 2nd year. Reducing heading more than 90% increased estimated in vivo DM digestibility and crude protein from 10 to 90 g kg−1units both years depending upon the chemical, and rate, and date of application. The 1st year's results indicated that metolachlor and mefluidide should be applied within a week of when the first floral primordia of foxtail barley develops for maximum control of heading but additional research should be done to confirm this. Moisture stress of foxtail barley during May of 1981 limited the effectiveness of the growth regulators in controlling heading the 2nd year.
Fertilizer Placement Effects on Growth, Yield, and Chemical Composition of Burley Tobacco1
Authors: Sims J. L. , Casey M. , Wells K. L.
Published: July 2010

Application of high rates of commercial fertilizers to burley tobacco (Nicotiana tabacumL.) soils through commonly used broadcast methods increases the osmotic pressure of the soil solution and soil acidity. Such changes in the soil may result in damage to plant roots, nutrient toxicities and deficiencies, delayed growth and maturity, and reduced yields. The current study was conducted to determine the influence of placing N and K fertilizers in bands of varying width between rows on selected chemical characteristics of soil (Maury silt loam, clayey, mixed mesic, Typic Paleudalf) and on growth, yield, and chemical composition of burley tobacco, cv. Ky‐14. Field experiments were conducted during 1979 to 1980 at two locations. Treatments consisted of 840 kg NH4NO3ha−1and 672 kg K2SO4ha−1applied either broadcast or in bands 80, 60, 40, and 20 cm wide centered between rows. Plant samples were taken at 45 days, and after maturity and curing for growth, yield, and chemical analysis. Surface soil pH depression in the row decreased as distance of the fertilized band from the row increased and pH in rows of the 20 cm band treatment remained about 0.3 to 0.5 pH units higher throughout the season than in broadcast treatments. The reverse was true for soil pH in the fertilized bands, with the 20 cm band treatment having lowest pH. Placement of the fertilizer in bands away from the row resulted in decreased electrical conductivity of the soil solution in the row, in decreased DTPA‐extractable Mn in the row, lower concentration of plant Mn and K, and fewer days to flower. In contrast, banding increased plant dry weight (21 to 40%) and plant Mg concentration at 45 days, cured leaf yields (9%), value per ha, and cured leaf alkaloid concentration.
Yield and Quality of Switchgrass Grown Without Soil Amendments1
Authors: Balasko J. A. , Burner D. M. , Thayne W. V.
Published: July 2010

Although cool‐season forages usually produce ample forage in spring and fall, there is a lack of summer pasture in many middle latitude and northern states in the USA. Low productivity in summer is accentuated in areas with soil and topographical limitations. The purpose of this study was to evaluate the productivity and nutritive value of ‘Blackwell’ switchgrass (Panicum virgatumL.) grown without addition of fertilizer or lime on a site of marginal fertility and harvested according to 10 cutting schedules. Plots were established on a fine‐loamy, mixed, mesic Ultic Hapludalf mapped as Culleoka‐Westmoreland and harvested according to one‐cut, two‐cut, and three‐cut schedules for 3 years. A residual harvest was made in early summer of 1981 to measure effects of previous cutting schedules on yield. Annual yields from the one cut per year schedules and the two cuts per year schedules with second harvests after frost were similar (7.3 to 8.1 Mg ha−1) and larger than those from other two and three cuts per year schedules. In vitro dry matter disappearance of switchgrass harvested at boot ranged from 504 to 576 g kg−1and decreased from 612 g kg−1on 10 July to 365 g kg−1on 16 September. Crude protein ranged from 30 to 70 g kg−1for all first cut forage. Quality of regrowth forage harvested before frost was higher than that of first cut forage, but regrowth usually represented less than 20% of seasonal yield. Results suggest that switchgrass managed in an extensive manner can contribute significantly to the amount of forage available to grazing beef cows in summer. Supplementation with protein, P, and Mg may be required as the opportunity for selective grazing is reduced.
Fate of 15N‐Depleted Ammonium Nitrate Applied to No–Tillage and Conventional Tillage Corn1
Authors: Kitur B. K. , Smith M. S. , Blevins R. L. , Frye W. W.
Published: July 2010

Crop recovery and soil immobilization of fertilizer N under two different tillage systems was observed in a 3‐year study. Corn (Zea maysL.) was fertilized with 84 or 168 kg N ha−1as 15N‐depleted NH4NO3. Nitrogen was surface applied as a solution on a Maury silt loam soil (fine , mixed, mesic Typic Paleudalfs). There was no mechanical disturbance of the soil in the no‐tillage treatment (NT); conventional tillage (CT) consisted of spring plowing and disking. Grain yields with NT tended to be lower than yields with CT at the low N rate but equal or greater at the high N rate. However, these differences were not statistically significant. In 1980 fertilizer recovery in grain was 21 vs. 38 kg N ha−1for NT and CT, respectively, at the low N rate. At the high N rate, N recovery by corn grown under NT and CT was not significantly different. Results were similar in 1981. After adding 15N‐depleted fertilizer to the same plots for 3 years, 71 to 75% of the fertilizer was accounted for in harvested grain, stover, or soil. Neither tillage nor N rate had a large effect on the fraction of fertilizer N missing and presumed lost by denitrification and leaching. Nitrogen fertilizer remaining in the NT soil was 42% of that applied at the low fertilizer rate and 39% of that applied at the high N rate. In the CT plots apparent immobilization was 28 and 37% for the low and the high N rate, respectively. Approximately one‐half of the N apparently immobilized was located in the surface 5 cm of the NT soil, but immobilized N was more uniformly distributed in the top 30 cm of the CT soil. Increased immobilization of N at the surface of the NT soil seems to be the most likely explanation for reduced crop recovery of fertilizer with NT at low N rates.
Basic Development Rate in Spring Wheat1
Authors: Flood R. G. , Halloran G. M.
Published: July 2010

There have been a number of reports indicating that, in the absence of vernalization and photoperiod influences, there is a factor(s) which acts to exert control over the rate of development in bread wheat (Triticum aestivumL. em. Thell.). In an attempt to characterize this phenomenon more fully, three sets of wheat genotypes were examined for their rate of development in the absence of vernalization and/or photoperiod influences. Seventeen spring wheats, prevernalized and grown with an 18‐h photoperiod in an outdoor pot experiment were found to differ in development rate, indicating that it may be of significance to adaptability and yield, at least in this type of wheat. In a set of near‐isogenic lines of ‘Triple Dirk’ (differing for the vernalization response genes vrn 1 and vrn 2) their development rates were similar, indicating that it is not a manifestation of the action of genes for vernalization response. Additionally, the absence of a close correlation between the level of vernalization response and basic development rate in the 17 spring wheats indicates physiological independence between the two processes. Using growth apex dissection the various phases of floral development were followed in two Australian spring wheat cvs., Pinnacle and Falcon, at four times of sowing in an outdoor situation and grown under an 18‐h photoperiod. The cv. Falcon was much faster than Pinnacle from sowing to floral initiation, terminal spikelet, and ear emergence at the four times of sowing. While the vegetative phase in Pinnacle was generally longer than in Falcon, the spikelet initiation and stem elongation phases did not show the same relative prolongation. ‘Chinese Spring’/‘Thatcher’ chromosome substitution lines 7B and SD, pre‐vernalized for weekly periods from 0 to 8 weeks and grown with an 18‐h photoperiod in an outdoor pot experiment were used to investigate the chromosomal control of development rate in wheat. Chromosome 7B of Thatcher substituted in Chinese Spring reduced its vernalization requirement and increased its rate of development. Chromosome 5D of Thatcher did not alter either vernalization response or rate of development of Chinese Spring. In view of these data and earlier reports, the term “basic development rate” is proposed to denote differences between wheats in the rate of development in the absence of vernalization and photoperiod influences. Recognition of the phenomenon of basic development rate prompts a re‐evaluation of the developmental basis of flowering in wheat and other temperate plants.
Modified Stability Analysis of Farmer Managed, On‐Farm Trials1
Authors: Hildebrand Peter E.
Published: July 2010

The Farming Systems Research and Extension (FSR/E) approach to technology generation and promotion is creating interest in onfarm research. Described is a form of research design and analysis that explicitly incorporates variation in farmer management as well as in soils and climate, to help agronomists evaluate responses to treatments and partition farmers into recommendation domains. Mean treatment yields at each location are used as an “environmental index.” Individual treatment results are regressed on environmental index. A graphic distribution of confidence intervals within partitioned groups helps in selecting superior treatments. Data from unreplicated trials on 14 farms in two villages in Malawi were analyzed. The design was a 2 ✕ 2 factorial with two maize (Zea maysL.) cultivars and two fertilizer treatments (0 and 30 kg N/ha). Results show that in poorer maize environments, local flint cultivars were superior to an improved semi‐flint composite, with or without fertilizer. The composite yielded more than local material with or without fertilizer in better environments. In all cases there was a marked and significant response to fertilizer.
Yield and Botanical Composition of a Grass‐Legume Mixture on Reclaimed Land as Affected by N and P Fertilizer1
Authors: Halvorson G. A. , Bauer A.
Published: July 2010

The study was conducted to determine the effect of fertilizer N and P on a grass‐legume mixture grown on land reclaimed following strip‐mining. Phosphorus was broadcast at rates of 0,6,17,50, and 150 kg P/ha in the fall of 1974. One‐third of the plots which received 6, 17, or 50 P/ha received no additional P during the course of the study; one‐third received an additional broadcast application of 6, 17, or 50 kg P/ha, respectively, in the spring of 1976 and one‐third received 6,17, or 50 kg P/ha, respectively, in the spring of each year from 1976 to 1981. Nitrogen was applied annually in the spring, on the same plots, beginning in 1975, at rates of 34,67, and 134 kg N/ ha. Fertilizer N applied at 134 kg/ha increased total forage yield from 11 to 45% compared to 34 kg N/ha. ‘Lincoln’ smooth bromegrass (Bromus inermusLeyss.) and wheatgrass sp. yields were increased 30 and 37%, respectively, in 1981 while botanical composition on a percent by weight basis increased 15 and 19%, respectively. Compared to the 34 kg N/ha rate, yield and percent composition of ‘Vernal‘ alfalfa (Medicago sativaL.) were decreased by the 134 kg N/ha rate. Total forage yields were not increased by fertilizer P. Yield and percent composition of wheatgrass increased with increasing additions of P, while the percent composition of smooth bromegrass decreased. Yields of smooth bromegrass and wheatgrass were highly correlated with the cumulative P applied 4 to 6 years prior to the 1981 harvest. Fertilizer recommendations based on soil test values accurately predicted response to N and P fertilizer.