bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Soil pH and Application Rate of Dairy Cattle Manure on Yield and Recovery of Twelve Plant Nutrients by Corn1
Authors: Hensler R. F. , Olsen R. J. , Attoe O. J.
Published: July 2010

Addition of increasing amounts of manure (0 to 613 m tons/ha) to both unlimed (pH 4.5) and limed (pH 7.3) Ella loamy sand gave increasing total dry matter yields of corn (Zea mays L.) in all cases. The yields were significantly higher for the medium rates of application (68 and 204 m tons/ha) on the unlimed soil than on the limed soil. Concentrations of Ca, Mg, P, S, Fe, and Mo in the plant tissue were usually higher for the limed soil than the unlimed soil, but the reverse was true for Zn and Mn. The higher concentrations in the tissue on the limed soil were probably due in part to more favorable conditions for microbial activity and degradation of soil organic matter. Total recovery of the individual nutrients from the manure by the three corn crops generally decreased with increasing rate of application, probably due to declining increases in yield and nutrient uptake with successive increments of manure. The dairy cattle manure, a mixture of 69% feces and 31% urine, contained 11.1% dry matter, and on the dry basis, 5.05% N, 0.87% P, 2.04% K, 1.59% Ca, 0.68% Mg, 0.46% S, 21 ppm Cu, 106 ppm Mn, 135 ppm Zn, 354 ppm Fe, 73 ppm B, and 4 ppm Mo. The data suggest that for soils near the neutral point, the nutrients in manure, even at very high rates of application, can be utilized in crop production and soil improvement with relatively little danger of plant toxicity.
Row Spacing and Population Effects on Corn Yields1
Authors: Lutz J. A. , Camper H. M. , Jones G. D.
Published: July 2010

During a 3‐year period at three locations, the effects of populations and row spacings on 10 corn (Zea mays L.) hybrids (early, medium, and late maturing) were evaluated. Grain yields were increased as the width between rows decreased. Yields were usually higher with the late maturing variety planted at a medium or high population. Some exceptions to this generalization were observed. Percentage moisture in the grain at harvest was not affected by row spacings or plant populations but was affected by the hybrid used. Ear weight ‐increased with a decrease in row spacing and plant population and with increased time required for maturity. The ear‐to‐stover ratio was greatly affected by hybrids but was little influenced by row spacings and plant populations.
Effect of Water Stress and Clipping on Photosynthate Translocation in two Grasses1
Authors: Sosebee Ronald E. , Wiebe Herman H.
Published: July 2010

Photosynthate translocation in crested wheatgrass (Agropyron cristatum (L.) Gaertn.) and cultivated barley (Hordeum vulgare (L.) cultivar ‘Hiland’) was studied under controlled environments. Treatments consisted of two levels of internal water stress (soil at field capacity or withheld for 4 to 7 days before isotope application) and three levels of defoliation (none, entire plant clipped to 10 to 15‐cm stubble height except for one tagged leaf, or entire plant clipped to 10 to 15‐cm stubble height except for one tagged leaf with the tip removed 8 to 10 cm from the collar.) Radiophosphorus applied to a photosynthetically active leaf was used to trace translocation to various plant parts.

Increased water stress decreased the total amount translocated from the mature leaf in both species. In barley, the water stress became more severe, and translocation beyond the sheath of the tagged leaf was negligible. Partial defoliation increased the translocation from tie tagged leaf to other plant parts, especially in plants grown without adequate water. Reduced water consistently increased the proportion of radiophosphorus translocated downward to the roots and crowns, while partial defoliation consistently increased the proportion transported to the younger leaves.
Influences of Method of Seeding and Moisture on Winter Wheat Survival and Yield1
Authors: Alessi J. , Power J. F.
Published: July 2010

Field experiments were conducted during 1963–1967 at Mandan, N. Dak., to compare effects of furrow and surface drilling methods and fall and spring moisture differentials on winter wheat (Triticum aestivum L.) survival and yield. A system was developed to permit collecting winter wheat plants from frozen soil for survival counts.

Average survival in February and March and final grain yields were significantly greater for furrow than for surface drilling. Survival often decreased substantially between early January and mid‐February, particularly in 1965 when survival decreased from over 90% to almost zero. Increased fall moisture also increased survival. Winter wheat survival was significantly correlated (r > 0.92) with cumulative degree days after December 1, calculated from a base of either _17.8 or −2.2°C. Furrow planting aided in trapping snow around the plant crowns, which may have reduced tissue desiccation and provided additional water during mid‐winter thaws. These results suggest, therefore, that the amount of protection afforded the crown, soil moisture conditions during the winter months, and intensity and duration of freezing prior to February 15 all affect winter wheat survival in frozen soils.
Effects of Soil‐Moisture Stress on the Yield and Quality of Flour from Wheat (Triticum aestivum L.)1
Authors: Day A. D. , Barmore M. A.
Published: July 2010

Effects of soil‐moisture stress at different periods during the growth of spring wheat planted in December on yield and quality of flour were studied under field conditions at Tucson, Arizona. Moisture stress at any stage of growth lowered wheat pastry flour quality. Moistures stress at the jointing stage resulted in a decrease in flour yield and an increase in flour protein, viscosity, and mixing curve area. Moisture stress at flowering resulted in an increase in flour protein, viscosity, and mixing curve area. Moisture stress at the dough stage decreased flour yield and increased flour protein, mixing curve peak, and mixing curve area. Increases in viscosities and mixing curve areas of flour from grain from stressed plants were due to the increases in flour protein content. Changes in the alkaline water retention capacity and mixing curve peak values were not related to changes in protein content and must be due to other factors resulting from moisture stress.
Effects of Soil Fumigation and the Form of Nitrogen on the Growth, Yield, and Value of Tobacco Grown on Two Soil Types. I. Plant Growth and Yield1
Authors: Gous Pieter J. , Terrill T. R. , Kroontje Wybe
Published: July 2010

During the 1967 and 1968 growing seasons flue‐cured tobacco was grown on a Cecil fine sandy loam and on Appling sandy loam on adjacent sites. Soil fumigation treatments included check (none), ridge and broadcast applications. Nitrogen was applied as all nitrate, all ammonium, half nitrate‐half ammonium, or half nitrate‐half ammonium with a nitrate sidedressing.

More rapid plant growth on the Appling soil late in the growing season resulted in a higher yield of cured leaves which was also reflected in a higher crop value. Differences in physical characteristics of the soil and especially internal drainage seem to be responsible for the better plant growth obtained on the Appling soil.

Application of all fertilizer nitrogen as NH4 resulted in the lowest yield and value of cured leaves during the first season. The NO3‐NH4 ratio of the applied fertilizer did not affect the quality of the crop produced or the ratio of stalk to leaf weight of the growing plants. During the second season lower quality cured leaves were obtained with the application of only NO3‐N. This was apparently related to excess leaching of NO3‐N resulting in a higher percentage of low quality leaves.

None of the treatments significantly affected the total particulate matter, nicotine content, or puff counts per cigarette. Seasonal differences, reflecting mainly the influence of different rainfall patterns, resulted in big differences in yield and value of cured leaves.
Harvest Index in Cereals1
Authors: Singh I. D. , Stoskopf N. C.
Published: July 2010

Harvest index values were studied in cereals during 1964 to 1967. A high degree of variability was found in the harvest index of winter wheat and other cereals. Stems contributed the greatest amount of dry weight to the straw yield and thus, as a vegetative part, materially influenced the harvest index. Reduction in plant height had the greatest effect on the stem dry weight and least on grain yield. Reduction in plant height lowered the dry weight of the vegetative parts and thereby lowered the straw yield which resulted in an increased harvest index. Harvest index was positively correlated with grain yield but negatively correlated with vegetative growth.
Distribution of P, K, Ca, Mg, B, Cu, Mn, and Zn in Peanut Lines Near Maturity1
Authors: Hallock D. L. , Martens D. C. , Alexander M. W.
Published: July 2010

The nutrient contents of peanuts (Arachis hypogaea L.) grown under nutrient‐sufficient conditions were determined in relation to yields of lines derived from 15 cultivars. Four plant portions of the lines, each a single seed selection, representing four market types were analyzed for contents of eight nutrients.

In general, the fruit was highest in P and Zn contents and lowest of the four portions in K, Ca, Mg, B, Mn, and Cu contents. The upper central stem leaves were highest in Ca, Mg, Mn, and B contents and intermediate in P, K, Zn, and Cu contents. The first lateral branch leaves were highest in K content, intermediate in P, Ca, Mg, B, and Cu contents and lower in Zn content than the above portions. Copper content was highest and P content lowest in the hypocotyl whereas the other nutrient contents in this portion were generally higher than in the fruit portion only.

Lines of the large‐seeded Virginia type were generally highest in K, Ca, and B contents, intermediate in Mg content, and lowest in P content of the four types. The small‐seeded Virginia type lines were highest in Mg content, equivalent in Cu and Mn content to the large‐seeded lines, and intermediate in P and K contents. The Spanish and Valencia lines were highest in P content, lowest in Cu content, but equivalent to the small‐seeded Virginia lines in K, Ca, B and Mn contents.
Soil Water Extraction by N‐fertilized Spring Wheat1
Authors: Bond J. J. , Power J. F. , Willis W. O.
Published: July 2010

Field experiments were conducted to determine the effect of applied N on water use by continuously cropped spring wheat. Applied N increased vegetative growth and soil water extraction prior to heading. In two of the three sample years, this extraction of the soil water reserve resulted in less soil water exraction after heading by the N‐fertilized crop than by the nonfertilized crop. Applied N did not increase depth of soil water extraction. Overwinter recharge of soil water was inversely related to soil water content at harvest.
An Ion Absorption Cell for Excised Root Studies1
Authors: Franklin R. E.
Published: July 2010

A simple, inexpensive absorption cell for use in studies with excised roots is described which facilitates the handling and processing of samples particularly when absorption times are short and quick changes of solution are desired.
Nutritive Value of Kochia scoparia I. Yield and Chemical Composition at Three Stages of Maturity1
Authors: Sherrod L. B.
Published: July 2010

Volunteer, wild stands of kochia (Kochia scoparia (L.) Schrad.) were harvested at three maturity stages to determine dry matter yield and composition and to evaluate kochia as a potential forage for livestock. The plants were in the prebloom stage of growth at the first cutting, mid‐bloom at the second, and full bloom at the third cutting. Dry matter yields and crude fiber levels increased and crude protein, percentage leaves, and. leaf: stem ratios decreased as stage of maturity advanced. Dry matter yields were 3,548, 8,708 and 11,327 ks/ha at the first, second and third stages, respectively. Crude protein ranged from 25.0 to 13.2%, and crude fiber from 17.9 to 37.0% of dry matter. Concentration of both macro and micro minerals either declined somewhat or remained almost constant as maturity progressed. These results suggest that kochia has high nutritive value as a forage for livestock, particularly in the earlier stages of growth.
Growth, Water Use, and Energy Balance Comparisons between Isogenic Lines of Barley1
Authors: Aase J. Kristian
Published: July 2010

Three barley (Hordeum vulgare L.) cultivars and their isogenic lines, with color (chlorophyll) as the variable, were tested under dryland conditions for various performance characteristics. Chlorophyll content and dry matter production were lower and growth stage development was later for the pale plants compared with their dark counterparts. Total water use was about the same for all cultivars and isogenic lines; however, water‐use efficiency was higher for the dark than for the pale plants.

Albedos were higher, canopy temperatures were lower, net radiation tended to be higher, and more of the energy was dissipated as sensible heat loss to the atmosphere for the pale compared with dark isogenic lines.
Effects of Soybean Seed Vigor on Field Performance1
Authors: Edje O. T. , Burris J. S.
Published: July 2010

The relationships of seed quality to field performance were studied by reducing the vigor of a high quality seed lot through artificial aging. ‘Amsoy’ and ‘Hawkeye’ soybean [Glycine max (L.) Merrill] seeds stored at 12.6–13.1% moisture and 40C decreased in field emergence and stand establishment. Treating seeds with Captan significantly increased the emergence percentage and the survival of only medium‐ and low‐vigor seeds. Once stand was established with medium‐ and low‐vigor seeds, there was no significant difference in yield between high‐, medium‐, and low‐vigor seeds. The effect of plant population was significant on yield. However, the differences in yield between vigor levels within populations were not generally significant. Hawkeye produced more dry matter than did Amsoy, but Hawkeye produced less yield. Over 50% of the total dry matter was made up of leaves 60 to 65 days after planting. Thereafter, stems and pods contributed over 50% of the total dry matter. Germination test of seeds harvested from test plots indicated that vigor, as induced by the aging method, was not transmitted.
Oxalate and Nitrate Contents of Four Tropical Leafy Vegetables Grown at Two Soil Fertility Levels1
Authors: Schmidt D. R. , MacDonald H. A. , Brockman F. E.
Published: July 2010

Total oxalate, soluble oxalate, and nitrate (NO3) were determined for leaves of Amaranthus cruentus L., Basella alba L., Brassica oleracea var. acephala D.C., and Ipomoea aquatica Forsk. grown on soils of medium and high fertility.

Differences among species were much greater than differences due to fertility. Average total oxalate contents on a dry weight basis were: Basella, 10.62%; Amaranthus, 8.86%; Ipomoea, 2.81%; and Brassica, <1.50%. Higher soil fertility resulted in increased total oxalate of about 25% in Amaranthus and Basella but no increase in Brassica and Ipomoea. Soluble oxalate ranged from 4.14% for Basella to 0.20% for Brassica.

Average nitrate contents were: Brassica, 2.80%; Amaranthus, 0.67%; Basella, 0.61%; and Ipomoea, 0.39%. Leaves grown on high‐fertility soil had an average of 125% more nitrate than those from medium fertility.

Implications of the results are discussed.
Separation of Degrees of Aluminum Tolerance in Wheat1
Authors: Kerridge Peter C. , Dawson M. D. , Moore David P.
Published: July 2010

A rapid, simple nutrient solution technique was developed for evaluating Al tolerance of wheat selections (Triticum aestivum Vill., Host). The effective Al concentrations in the screening solutions were maintained within narrow limits by controlling the phosphorus concentration and the pH. Differences in tolerance, notably for root elongation, were evident shortly after germination and were of the same relative order as when plants were grown in acid soils of varying exchangeable Al levels. Approximately 50 varieties were screened for their tolerance to Al, and they fell into three groups: (1) tolerant at 6.4 ppm, (2) tolerant at 2.4 ppm but sensitive at 6.4 ppm, and (3) sensitive at 2.4 ppm. The advantages of the nutrient solution method over the soil method for screening for Al tolerance are discussed. A biological rest was proposed for assessing Al in soils based on the differential response of lines of widely varying tolerance.
Effects of Herbicides and Seeding Rates on the Production of Alfalfa1
Authors: Moline W. J. , Robison L. R.
Published: July 2010

Spring seedings of alfalfa (Medicago satva L.) were established using various seeding rates and establishment treatments. During the year of establishment, average total dry matter yields of alfalfa increased with increased seeding rate. Seeding rates of 24 kg/ha produced alfalfa yields lower than those of the 3 kg/ha seeding rates in cuttings taken the year following seeding. Higher yields of alfalfa were obtained at the lower seeding rates of 3 and 10 kg/ha using EPTC and benefin than at seeding rates of 17 and 24 kg/ha using 2,4‐DB plus dalapon, oats, or check. Weed yields were reduced by all establishment treatments. The effect of establishment treatment was significant during the year of seeding, but not in the year following. Seeding rate effects remained significant throughout six cuttings taken the first two years of the trial. The use of preplant herbicides and seeding rates of 10 or 17 kg/ha were superior in establishing stands of spring seeded alfalfa.
Effect of Soil Temperature on Mineral Element Composition and Morphology of the Potato Plant1
Authors: Epstein Eliot
Published: July 2010

The influences of two soil temperatures, 5 and 29 C, were studied on potato (Solanum tuberosum) plant growth, tuber yield, and potato plant morphology. The low soil temperature enhanced tuber initiation. Analysis of several minerals showed that the Mn ratio of tops to roots was 0.42 at 5 C and 2.84 at 29 C. At 5 C proliferation and xylem development of roots was restricted, whereas at 29 C the xylem was highly developed. Starch grains were present in the phloem at 5 C but absent at 29 C. This fact suggests that there is a relationship between the assimilate balance and tuber initiation.
Internal Water Stress and Apparent Photosynthesis with Soybeans Differing in Pubescence1
Authors: Ghorashy S. R. , Pendleton J. W. , Peters D. B. , Boyer J. S. , Beuerlein J. E.
Published: July 2010

Three near‐isogenic lines (isolines) of ‘Clark’ soybeans [Glycine max (L.) Merrill] differing greatly in pubescence characteristics (dense pubescent, normal, and glabrous) were subjected to water stress during flowering or podfilling stage under field conditions. During these developmental stages, apparent photosynthesis (AP) rates of fully expanded top leaves were measured using a single leaf chamber, and water potential was determined on the same leaves using the pressure chamber technique. AP rates decreased linearly as leaf water potential decreased. The decrease was less during the flowering stage than during pod‐filling stage for all three isolines. Under nonstressed conditions (—1 bar soil water potential), AP rates for normal, dense pubescent, and glabrous were 119.8, 73.4, and 76.0% higher during pod‐filling stage than during following
Supplemental Feeding of Steers on Festuca arundinacea Schreb. Pastures Fertilized at Three Levels of Nitrogen1
Authors: Mott G. O. , Kaiser C. J. , Peterson R. C. , Peterson Randall , Rhykerd C. L.
Published: July 2010

The production of tall fescue (Festuca arundinacea Schreb.) in terms of gain of yearling steers, carrying capacity, liveweight gain per hectare and estimated total digestible nutrients per hectare (ETDN) was measured during four successive years. Tall fescue was fertilized with ammonium nitrate at the rates of 0, 84, and 168 kg/ha of elemental nitrogen. Crimped corn was fed daily at the rate of 1 kg per 100 kg of body weight on one‐half the pasture. Corn greatly increased average daily gain, carrying capacities of the pastures and total amount of liveweight increase per hectare. N fertilizer slightly depressed average daily gain, nearly doubled carrying capacities of the pastures and greatly increased liveweight increase per hectare. The seasonal pattern of liveweight gain was altered by feeding grain, indicating that a low level of energy intake is one of the factors limiting rate of production of steers on tall fescue pasture. N fertilizer prevented development of volunteer legumes in the fescue pastures.
Differential Response of Corn Inbreds and Single Crosses to Certain Properties of an Acid Soil1
Authors: Lutz J. A. , Hawkins G. W. , Genter C. F.
Published: July 2010

Three greenhouse experiments were conducted in 1969 and 1970 in which maize (Zea mays L.) inbred lines and single crosses were grown on an untreated acid Greendale silt loam (pH 3.9) and on the same soil adjusted with pulverized dolomitic limestone to various pH levels. Plant‐height measurements were made and dry‐weight yields were determined 27 to 38 days after planting.

There were highly significant differences in growth among entries under highly acidic conditions. Inbred lines Connecticut 103 and Minnesota A632 grew very poorly in highly acid soil, while inbred lines Iowa B37 and Virginia 17 and two single crosses appeared to be tolerant to high acidity. There was a significant interaction between growth of entries and pH levels.
Influence of Temperature and Nitrogen Fertilization on the Growth and Composition of Switchgrass (Panicum virgatum L.) and Timothy (Phleum pratense L.) at Anthesis1
Authors: Balasko J. A. , Smith Dale
Published: July 2010

Yield and chemical composition of the plant parts and total herbage of switchgrass (Panicum virgatum L.) and timothy (Phleum pratense L.) at anthesis were studied in growth chambers. The grasses were established in pots of Plano silt loam soil by transplanting young, unelongated tillers. They were grown to anthesis in four day/night temperature regimes (32/26, 27/21, 21/15, and 15/10 C) at two soil N levels; 60 and 260 kg/ha.

Days required for the grasses to reach anthesis decreased as day/night temperatures increased to 27/21 C and then remained the same at 32/26 C. N fertilization did not affect time to anthesis. Neither N nor temperature affected inflorescence numbers of either species, but N increased inflorescence lengths.

Vegetative growth measures at anthesis were greatest for switchgrass in the highest temperature regime (32/26 C) and for timothy in the low or mid‐temperature regimes (15/10 C and 21/15 C). N increased these parameters for both species.

Total nonstructural carbohydrate (TNC) percentages in the herbage, stubble, and rhizomes of switchgrass at anthesis were not affected greatly by temperatures or N. TNC percentages for the plant parts of timothy were generally highest in the lowest temperature regime and lowest in the highest temperature regime. N decreased TNC percentages for the herbage and stubble of timothy, but had little effect on those of the roots.

Mineral concentrations in the herbage of both species at anthesis were generally highest in the temperature regimes where the species produced the least growth (15/10 C to 21/15 C for switchgrass and 32/26 C for timothy). N generally increased nutrient element concentrations.
Soil Water Suction and Root Temperature Effects on Nitrogen Fixation in Soybeans1
Authors: Kuo Tsungmin , Boersma L.
Published: July 2010

The effect of soil water suction and root temperature on rates of nitrogen fixation, transpiration, and net photosynthesis of soybeans (Glycine max (L.) Merr.) was studied in laboratory experiments. The range of root temperature and soil water suction considered was 15.6 to 37.8 C and 0.30 to 2.50 bars, respectively. With increasing root temperature rates of nitrogen fixation, transpiration and photosynthesis increased slowly at first and then rapidly until an optimum temperature was reached followed by a decrease at higher temperatures. Optimum temperatures were 27, 30, and 27 C for rates of nitrogen fixation, transpiration, and net photosynthesis, respectively. Rates of the three parameters decreased with increasing soil water suction. The amount of nitrogen fixed per unit of CO2 absorbed was highest at a root temperature of 23.9 C and lowest at 37.8 C. This ratio decreased with increasing soil water suction at all temperatures considered. Changes in transpiration rate resulting from changes in soil temeprature were attributed to temperature effects on viscosity and metabolic activity.

Effects of soil water suction and soil temperature on nitrogen fixation indicated in this study emphasize the complex symbiotic nature of the process. Mechanisms by which the two environmental parameters might affect the rate of fixation were indicated but not clearly elucidated by the results of the experiments.
Relationship of Indole Alkaloids to Palatability of Phalaris arundinacea L.1
Authors: Simons A. B. , Marten G. C.
Published: July 2010

We screened 411 diverse genotypes of reed canarygrass (Phalaris arundinacea L.)for palatability to sheep. Indole alkaloid type and concentration were estimated in selected plants by either the xanthydrol method or by total base titration; the methods were highly correlated (r = +0.94).

Either gramine or 5‐methoxy‐N,N‐dimethyltryptamine (5‐MeO‐DMT) + N,N‐dimethyltryptamine (DMT) were the primary alkaloids in all genotypes. No apparent relationships existed between palatability and individual alkaloid type. Results of 372 alkaloid determinations over three gratings in the 1st year indicated a negative correlation (r = ‐0.83) between total alkaloid percentage and relative palatability. The linear relationship was strongest between palatability ratings 5 to 10 on a scale of 1 (completely consumed) to 10 (completely rejected).

Two groups of nine genotypes were clonally propagated to replicated plots for further grazing trials under restricted choice conditions during the 2nd year. When the groups were grazed separately in balanced lattice designs, relative palatability and total alkaloid concentration were linearly related (r = ‐0.95 and ‐0.92) in two experiments. These variables were also linearly related (r = ‐0.95) when the 18 clones were later grazed together in a randomized complete block design.

Alkaloid concentrations in the 18 clones ranged from 0.18% to 1.21% of the dry matter and were similar between years and between grazings. Palatability ratings were also generally similar under the several different grazings situations.

We concluded that determination of total alkaloid concentration is a valid means of screening for palatability in reed canarygrass.
Emergence and Survival of Cool Season Grasses under Drouth Stress1
Authors: Wood Glen M. , Kingsbury Paul A.
Published: July 2010

Alternating moist and dry periods were used to evaluate 19 grasses, including six genera and several cultivars of some, in a growth chamber experiment. Two types of drouth tolerance were demonstrated: drouth tolerance of seedlings and presence of dormant or quiescent seeds that can survive alternate dry and moist periods. A grass significantly higher in the first type of drouth resistance was ‘Sawki’ Russian wildrye (Elymus junceus Fisch.). Pennlate orchardgrass (Dactylis glomerata L.) showed a very high degree of drouth tolerance of the second type.
Distribution of Total and Available Sulfur in Selected Soils and Soil Profiles1
Authors: Tabatabai M. A. , Bremner J. M.
Published: July 2010

Sulfur deficiencies have been detected in several regions of the United States during the past decade, and sulfur fertilization is now required in many areas to ensure satisfactory crop production. The purpose of the work reported was to assess the sulfur status of Iowa soils and obtain information required for evaluation of the need for sulfur fertilization.

Analysis of 64 surface soils representing the major soil series in Iowa indicated that 95‐98% of the total S in iowa surface soils is organic S. The total S contents of the soils analyzed ranged from 57 to 618 ppm (average, 294 ppm), and the sulfate‐S contents ranged from 1 to 26 ppm (average, 9 ppm). Studies with selected soils showed that they did not contain significant amounts of adsorbed sulfate S or mineralizable S and had little, if any, capacity to adsorb sulfate. Total S was significantly correlated with organic C (r = 0.85**) and with total N (r = 0.90**), and sulfate S was significantly correlated with total S (r = 0.57**). Mineralizable S was not significantly correlated with total S, sulfate S, organic C, total N, mineralizable N, or arylsulfatase activity. Analysis of profile samples of representative Iowa soils showed that total S decreased markedly with increase in sample depth and that subsurface samples usually contained less sulfate S than did surface samples. The data reported indicate that Iowa soils have low reserves of plant‐available S
Germination, Emergence, Water Use, and Production of Russianthistle (Salsola kali L.)1
Authors: Dwyer Don D. , Wolde‐Yohannis K.
Published: July 2010

Studies of Russianthistle (Salsola kali L.) have shown that it is a plant well suited to arid and semi‐arid regions. This study was conducted to learn some of the characteristics of the species related to germination and water use that allow it to succeed in these dry areas. Russianthistle seeds were planted in a sandy soil, and various amounts of simulated rainfall were added once. Emergence occurred in 14 hours when as little as 7.6 ml (0.3 inch) was applied. There was no significant difference in numbers of plants emerging and surviving to permanent wilting from 12.7 ml (0.5 inch) to 27.9 ml (1.1 inch) of simulated rainfall. Germination studies showed that Russianthistle seed germinated from 4 to 68 C with optimum germination from 7 to 35 C. Plants were grown for 90 days (to maturity) at four soil moisture levels — field capacity, 0.5, 0.2, and 0.1 available water — to determine water use and production. Shoot production was greatest at field capacity and least when soil was maintained at 0.1 available water. However, efficiency of water use was greatest at 0.1 available water, requiring only 98 g of water per dry‐weight gram of shoot produced. Even under field capacity, Russianthistle used only 181 g of water per dry‐weight gram of shoot and root produced.
Combining Experiments to Predict Future Yield Data1
Authors: Cady Foster B. , Allen David M.
Published: July 2010

Data front a series of fertility experiments including uncontrolled environmental variables are analyzed so that future yields may be predicted. Existing regression procedures for selecting variables in an estimated prediction equation had been found to perform poorly when used for new sets of similar data. A new criterion, the prediction sum of squares, based on the performance of the estimated equation for predicting observations not included in the least squares estimation, is developed for selecting the best predictor variables. The procedure gives an estimated prediction equation with a minimal number of predictor variables, including few interaction variables. Agronomically reasonable estimates of the regression coefficients also are obtained. Using the new procedure, a 30% reduction in the sum of squared deviations between the observed and the predicted observations compared with the stepwise regression method is found. Response curves are constructed for use in making soil test recommendations.
Effects of Stalk Chopping on Leaf Removal and Juice Quality of Rio Sweet Sorghum1
Authors: Broadhead Dempsey M.
Published: July 2010

Mechanized stripping is essential for survival of the sweet sorghum sirup industry and continued development of the sweet sorghum sugar industry.

‘Rio’ sweet sorghum [Sorghum bicolor (L.) Moench.] was planted April 1 and 15, May 1 and 15, and June 1 and 15 and harvested in flower, milk, dough, and ripe stages and at 1, 2, 3, and 4 weeks after ripe stage of maturity. Stripped stalk samples from each planting date and harvesting stage were chopped into 10‐, 20‐, and 40‐cm sections on a bench saw and compared with whole stalks in storage for 0, 24, and 48 hours. Unstripped stalks were chopped into 10‐, 20‐, and 40‐cm sections to evaluate chopping as a technique for separating leaves and stalks. Chopping the stalks into short sections was an effective method of separating leaves from the stalks. Under the conditions of these experiments no important losses were indicated in juice quality, as measured by Brix, sucrose, and purity of stalk sections when compared to whole stalks of sweet sorghum in storage for 0, 24, and 48 hours.
Nitrogen Nutrition of Field‐grown Soybean Plants: I. Seasonal Variations in Soil Nitrogen and Nitrogen Composition of Stem Exudate1
Authors: Streeter John G.
Published: July 2010

This study was undertaken to document the quantities of N compounds present in soil and in stem exudate from soybeans throughout most of the life cycle of the plant. The results provide new information on the relative importance of various N compounds involved in translocation and the relation of these compounds to soluble N of the soil.

Soybean plants (Glycine max L. Merr., ‘Harosoy 63’) were grown under field conditions in Wooster silt loam with four replications. Nodules formed on the roots early in the season, and plants were well nodulated throughout the growth period. Plots were sampled at 13 times during the growing season for the determination of soil moisture, nitrate and ammonium content of the soil, and nitrate, nitrite, and amino acid content of stem exudate.

Exudate flow rate appeared to be related to soil moisture content early in the season but the relationship was not maintained after the flowering stage. Nitrite was not detected in stem exudate. Nitrate content of the soil and the exudate was highest during the growing stages preceding flowering. During growth stages following flowering the amino acid concentration in the exudate was many times the nitrate concentration, which did not vary with fluctuations in nitrate content of the soil. Asparagine was the predominant amino acid in the stem exudate at all harvest dates; asparagine N as per cent of total amino acid‐N was 61% over the entire experiment. The grand mean for amino acid‐N concentration in exudate was double the grand mean for nitrate‐N concentration.
Noncompetitive Effects of Giant Foxtail on the Growth of Corn1
Authors: Bell David T. , Koeppe D. E.
Published: July 2010

Weed infestations severely reduce the yield grown corn with such yield reductions generally being attributed to competition. Noncompetitive (allelopathic) mechanisms have to date, however, received little consideration in agronomic situations. In the greenhouse, interference (competition + allelopathy) of the growth of corn (Zea mays L. Wf9 ✕ M14) by giant foxtail (Setaria faberii Herrm.) was determined in mixed culture treatments. When corn was seeded into pots with 6‐week‐old giant foxtail, corn height, fresh weight, and dry weight were reduced by as much as 90% when compared to comparable plants grown in monoculture. Competitive and allelopathic mechanisms were separated through the use of a stairstep apparatus, in which a nutrient solution passed through the rhizosphere of giant foxtail, into the rhizosphere of corn and was subsequently recycled through the system. The stairstep apparatus was used to determine the allelopathic interactions between corn and giant foxtail seedlings, mature giant foxtail, whole dead giant foxtail plants, and mascerated dead giant foxtail leaf and root material. Mature giant foxtail inhibited the growth of corn approximately 35% through an allelopathic mechanism. Elimination of competition through the use of stairsteps apparatus implicates a possible allelopathic mechanism in the interference of corn by giant foxtail that involves the exudation and leaching of phytotoxins from the roots of giant foxtail. Phytotoxins leached from dead giant foxtail reduced corn growth by as much as 50%. The relationships of allelopathy to competition, crop rotation, herbicidal activity, and physiological processes are discussed.
Soil Surface Water Depletion and Leaf Temperature1
Authors: Aston A. R. , van Bavel C. H. M.
Published: July 2010

This work explores the feasibility of the remote detection of water depletion in a cropped field. It proposes that this may be accomplished by detecting the increase in the visible and thermal radiant heat loads upon plant leaves when the underlying soil surface dries. A theoretical model was constructed, relating leaf temperature to soil surface temperature.

Parallel experiments were done using a grey podzolic soil. It was found that in spite of an increase of 15% in reflectivity upon drying, there was an increase in soil surface temperature from 20 to 50 C. The increased shortwave and longwave radiant loads on leaf arrays in the experiments, resulted in leaf temperature increases of 2.5, .5, and 2 C in dry blotting paper, wet blotting paper, and leaves of the southern pea (Vigna sinensis), respectively.

The leaf energy balance‐soil water depletion model predicted these increases, as well as the absolute temperatures, with an accuracy of 1 and 5% for the artificial and real leaves, respectively.

The findings of this study affirm that a technology can be developed for the remote detection of soil water depletion in field crops, but that the temperature differences involved are both small and variable.
Nature of Scion Control of Mineral Accumulation in Soybeans1
Authors: Polson D. E. , Smith L. J.
Published: July 2010

A modified grating technique was used to study scion control of mineral accumulation in soybeans [Glycine max (L.) Merrill]. With this technique the shoot is left intact and a second scion or shoot is grafted into the first. We compared mineral accumulation in the original and graft shoot using this technique to determine if scion control of ion accumulation is accomplished within the shoot itself or if the shoot acts through altering root characteristics.

Grafts were made in all combinations among four genotypes differing in accumulation levels for a number of ions. The original and graft shoot accumulated different levels of P, K, Ca, Mg, Sr, and B in seed, depending upon the genotype of the original and graft shoot. Accumulation in original shoot leaves was independent of the graft genotype. Accumulation in graft shoot leaves was primarily a function of the graft shoot genotype, although the original shoot had some effect on accumulation of P, Ca, Mg, Zn, and B. These results indicate that ion accumulation in the original and graft shoot is largely independent, suggesting that scion control of ion accumulation is accomplished via a self‐contained mechanism within the shoot.
Effect of Planting Date and Maturity on Juice Quality of Rio Sweet Sorghum1
Authors: Broadhead Dempsey M.
Published: July 2010

Economical production of granulated sugar from immature sweet sorghum stalks would extend the milling period for several weeks each year.

‘Rio’ sweet sorghum [Sorghum bicolorz (L.) Moench.] was planted April 1, May 1, and June 1 and was harvested in the flower, milk, dough, and ripe stages of maturity. Samples from each planting date and harvesting stage were stored openly on the ground for 0, 24, and 48 hours before milling. The juice was weighed and analyzed for Brix, sucrose, and purity to compare the effect of maturity and storage on juice quality.

Yield of stalks from the April 1 and June 1 plantings were similar but significantly lower than from the May 1 planting date. Stage of maturity had no effect on yield of stalks. Extraction generally decreased with maturity, whereas Brix and starch increased. Sucrose increased with maturity through the dough stage and purity increased from flower to milk stage.

Extraction and purity decreased during 24 hours in storage, and sucrose and starch decreased during 48 hours in storage. Sucrose inversion was highly significant in stored stalks harvested in the flower and milk stages, which resulted in a highly significant decrease in purity. Mature stalks showed little or no inversion during storage. Juice purity was similar for Rio stalks harvested in the milk, dough, and ripe stages of maturity and not stored. After 24 hours in storage purity of stalks harvested in the milk stage was significantly lower than that of those harvested in the dough and ripe stages.
Interaction of Nematodes and Soil Temperature on Growth of Three Tropical Grasses1
Authors: Boyd F. T. , Schroder V. N. , Perry V. G.
Published: July 2010

Yields of several pasture grasses in Florida are seriously reduced by nematodes. This study investigated the relation between soil temperature and growth of grasses.

Three tropical grasses were planted in soil infested with parasitic nematodes and were grown under greenhouse conditions at eight temperature levels. These temperature levels were established in a water‐bath consisting of an insulated, copper‐lined, wooden tank equipped with electrical heating and cooling controls.

Soil temperatures influenced the amount of plant injury from parasitic nematodes, but the degree of such injury was dependent on the type of nematode present and on the susceptibility of the host plant.

Sting nematodes (Belonolaimus longicaudatus Rau) were most active at soil temperatures between 20 and 34 C. Pensacola bahiagrass (Paspalum notatum Flugge) and limpograss [Hemarthria altissima (Poir) Stapf et C. E. Hubb P.I. 299994] produced greatest forage yields when soil temperatures were between 34 and 38 C. At the temperatures tested above 38 C, sting nematodes were greatly reduced, but ring nematode (Criconemoides spp. Taylor) populations were maintained. Forage yields of pangola digitgrass (Digitaria decumbens Stent) were highest when grown at temperatures between 38 and 41 C.
Effect of Day/Night Temperature on Factors Associated with Growth of Nicotiana tabacum L. in Controlled Environments1
Authors: Haroon Mohammed , Long R. C. , Weybrew J. A.
Published: July 2010

Growth of flue‐cured tobacco (Nicotiana tabacum L.), ‘NC2326,’ was studied under controlled conditions in the North Carolina State University Phytotron (Southeastern Plant Environment Laboratory) to determine the patterns of growth over a wide range of day/night temperatures. Day temperatures ranged from 18 to 34 C at 4‐C intervals; night temperatures ranged from 14 to 30 C at 4‐C intervals. The growth of seedlings from first leaf to transplant size (Experiment I) was determined weekly intervals under all possible day/night temperature combinations. Fresh weight, dry weight, and leaf number were affected to a greater extent by night than by day temperature. The minimum night temperature for growth lies between 18 and 22 C. The 34/30 treatment yielded maximum fresh and dry weights, while maximum leaf number occurred under the 34/26 treatment. Diurnal variation in temperature favored increased growth. During early stages of seedling growth fresh and dry weight accumulation exhibited a bimodal response to day temperature.

The growth of plants from transplant size to appearance of the first flower (Experiment II) was studied under the following day/night temperatures: 34/30, 30/26, 26/22, 22/18, and 18/14. Whole‐plant fresh and dry weights, leaf fresh and dry weights, leaf number, and plant height increased with temperature to 30/26, but decreased slightly at 34/30. Days‐to‐flower decreased with temperature to 26/22 and then increased at higher temperatures.
Influence of Subsurface Barrier on Growth, Yield, Nutrient Uptake, and Water Requirement of Rice (Oryza sativa)1
Authors: Rao K. V. P. , Varade S. B. , Pande H. K.
Published: July 2010

Growth of rice (Oryza sativa) under flooded conditions in Southeast Asia results in excessive water and N losses. This investigation was conducted to determine the effect of subsurface barriers of bitumen and concrete on yields of rice grown with 60, 90, and 120 kg/ha of N. Yields of rice grown over the subsurface barriers were significantly higher than those grown on the control. The increase in growth and yield of rice was attributed to increased uptake of N, P, and Fe rendered available due to conducive redox potential. Rice produced significantly higher yields with 90 or 120 kg/ha of N than with 60 kg/ha. Subsurface barriers reduced the water requirement drastically and increased water use efficiency.
Crop Response to Phosphate Fertilization and to Residual Phosphate Levels: II. Evaluation of Residual Phosphorus “Availability” by Chemical and Plant Tests in a Greenhouse1
Authors: Giskin M. , Hagin J. , Kafkafi U.
Published: July 2010

Yield response in two field experiments was found to be a poor indicator of phosphorous “availability”. This greenhouse experiment was performed in order to obtain an indicator of “availability” based on plant response in addition to those based on soil extraction methods.

Bulk samples of soil were taken from each of 16 treatments of two field experimental sites (Neve Yaar and Lachish) on which eight consecutive crops had been grown and differentially fertilized. The residual P levels (NaHCO3‐soluble P) ranged from 5.5 to 24 ppm P. The greenhouse treatments consisted of four levels of phosphate applied as triple superphosphate in amounts of 0, 40, 100, and 250 ppm P to pots containing 3 kg of soil.

Within greenhouse treatments, at any one residual level, the absolute yield on the Lachish soil increased with increasing rates of P application. For the Neve Yaar soil this held only up to a residual level of 11 ppm P. In both soils, with few exceptions, the larger the residual P level (field treatments), the smaller the yield increase due to the fertilizer treatments given in the greenhouse (i.e., at residual level of 5.6 and 24 ppm P the step wise dry matter yield increases were from 1.29 to 6.25 and 4.40 and 5.31 g/pot respectively).

Relative yields, chosen as an indicator of P “availability” in soil, of the nonfertilized pots of the greenhouse experiment were correlated to amounts of P applied in the field. Relative efficiencies of the residual phosphate accumulated in the field experiments, as described by the slopes of the regression lines, showed an inverse dependence on the heavy superphosphate applications (48–432 kg P/ha) applied to the field experiments. This suggests a higher efficiency of fertilizer P, can be obtained on calcareous soils, when applied in small annual amounts.
Essentiality of Molybdenum for Alfalfa on Highly Oxidized Piedmont Soils1
Authors: Giddens Joel , Perkins H. F.
Published: July 2010

Production of alfalfa (Medicago sativa L.) has steadily declined on highly oxidized soils of the Southeast during the past decade. An investigation was conducted to determine if lack of Mo is responsible and if lime or N replaces the Mo requirement of alfalfa and if there are other alternatives such as use of CaSO4 and Mo to replace lime, MgCO3 substitution for CaCO3, and if high initial lime applications may replace lesser annual applications. Field investigations using two highly oxidized Udults revealed that neither N at 67 kg/ha, nor lime at initial rate of 11,200 kg/ha or annual applications of 2,240 kg/ha replaced the Mo requirement of alfalfa. Nitrogen increased crabgrass (Digitaria sp.) competition, which resulted in less alfalfa forage. Calcium from CaSO4 with or without Mo did not maintain alfalfa. MgCO3 and CaCO3 applied at equivalent rates were equally effective as liming materials. An initial lime treatment of 11,200 kg/ha produced yields equal to that obtained by annual application of the same total amount of lime over a 5‐year period.