bluuebunny/crossref_metadata_2025 huggingface dataset:
Loss of Nitrapyrin from Soils as Affected by pH and Temperature1
Authors: Touchton J. T. , Hoeft R. G. , Welch L. F. , Argyilan W. L.
Published: July 2010

Little information is available on soil characteristics that influence the persistence of nitrapyrin [2‐chloro‐6‐(trichloromethyl) pyridine] in soil. Knowledge concerning these characteristics could be helpful in determining the most effective time of nitrapyrin application and in identifying soils in which the most effective inhibition of nitrification by nitrapyrin might be expected. The objective of this study was to evaluate the effects of soil pH and temperature on the disappearance of nitrapyrin and ammonium‐N from the soil. Nitrapyrin was applied at rates of 2 and 4 ppm to three soils with pH levels adjusted to approximately 5.5, 6.3, and 6.8. In two of the three soils, the rate of nitrapyrin disappearance increased with increasing pH levels. However, nitrapyrin concentrations in the soil at the end of the 83‐day incubation period were equal among pH levels. When pH influenced nitrapyrin disappearance, recoverable nitrapyrin decreased curvilinearly with time. When pH had no apparent effect on nitrapyrin, recoverable nitrapyrin decreased linearly with time.

In the temperature study, nitrapyrin and N were applied to Drummer (Typic Haplaquoll) and Cisne (Mollic Albaqualf) soils and incubated for 154 days at temperatures of 4, 13, and 21 C. Disappearance of nitrapyrin and ammonium‐N occurred at all temperatures and increased with increasing temperatures. The half life of nitrapyrin in the Cisne soil was 22 days when incubated at 4 C, and less than 7 days when incubated at 13 and 21 C. The half life of nitrapyrin in the Drummer soil was 92, 44, and 22 days, when incubated at temperatures of 4, 13, and 21 C, respectively. At all temperatures nitrapyrin was more effective in controlling loss of ammonium in the Drummer than in the Cisne soil.
Canopy Temperatures: the Usefulness and Reliability of Remote Measurements1
Authors: Hatfield J. L.
Published: July 2010

Remote measurements of leaf temperature offer a quick means of measuring individual leaf or canopy temperatures. The spatial area measured depends on the viewing angle of the infrared thermometer. This study was designed to evaluate the measurement of leaf temperature with attached vs remote measurements for a field row crop and to determine the relationship between angular and vertical temperature measurements for the seasonal growth of durum wheat. Leaf temperatures, measured with attached thermistors and thermocouples, were compared with those remotely observed with infrared thermometers to determine the accuracy of a remote measurement of leaf temperature.

Small thermistors or thermocouples were attached to the underside of a leaf to measure leaf temperature and remotely measured with a Barnes PRT‐5 infrared thermometer with 2° field of view and 10.5–12.5 μm waveband, sited on the same leaf. These data were continuously, recorded for several days. These measurements were made on selected leaves from a field grown Gloria Pink bean (Phaseolus vulgaris L.) canopy in August 1976. Agreement was good for an individual leaf when the infrared measurement and attached thermistor measured the same location on an individual leaf. When the canopies or a composite of leaves were observed with infrared thermometers held vertically about one meter above the canopy and only selected leaves were measured with attached thermistors, the agreement was less good. Correction of infrared measurements to an emissivity of 0.96 decreased the difference between the two measurements in the afternoon (1330 hours PST) but increased the difference for the predawn readings. This suggests that one simple emissivity correction would not be sufficient. When angular measured canopy temperatures were compared with vertical measurements with the infrared thermometer throughout the growing season in durum wheat (Triticum durum Desf. ‘Produra’) canopies the difference between the two angular measurements was attributed to the amount of canopy seen by the infrared thermometer. When the canopy was sparse, the difference was minimal and increased to a maximum when the cover was between 20 and 50% and then decreased as the canopy became more full. Infrared temperature measurements provide reliable and accurate measurements of leaf temperature without physical attachments to the leaf. When the canopy is less than full, care has to be exercised to observe the canopy rather than a composite of soil and plants.
A Rapid Method for Obtaining Leaf Impressions in Grasses1
Authors: Rice J. S. , Glenn E. M. , Quisenberry V. L.
Published: July 2010

Most leaf impression methods described in the literature are time‐consuming and unsatisfactory for use on ribbed or pubescent grass leaves. We have developed a rapid method to make leaf impressions in grasses. A vinyl solution is applied to the leaf surface with a camel‐hair brush and allowed to dry. A strip of transparent tape with adversive on both sides is attached to a microscope slide. The slide is applied to the leaf with the tape in contact with the vinyl film. The other leaf surface is rubbed to insure good contact between the tape and vinyl. The impression is then slowly lifted off with the slide. After a cover slip is applied, the impression can be viewed immediately or stored for an extended period of time.
Soybean Yields in Relation to Days Between Specific Developmental Stages1
Authors: Dunphy E. J. , Hanway J. J. , Green D. E.
Published: July 2010

Environment, production practices, and genetic differences are known to influence the number of days between developmental stages of soybeans [Glycine max (L.) Merr.], but the yield response to differences in days between various stages is poorly understood. Twice weekly observations were made on 10 central Iowa replicated field trials over a 3‐year period to determine the date that each plot reached several specific stages of plant development. These dates and final seed yields were utilized to investigate whether number of days between specific stages of development were associated with final seed yield. All sites were mapped as Webster silt loams (a member of the fine‐loamy, mixed noncalcareous, mesic family of typic haplaquolls). Variations among the 119 cultivars represented in the study accounted for more of the differences in days between developmental stages than did sites or years. There was no association between seed yield and number of days between any two vegetative stages of development. The length of the seed development period [days from stage R4 (pods 2 cm long at top four nodes) to R7 (pods yellowing)] was more highly correlated with seed yield than was the length of any other developmental period. Plots which initiated flowering later and matured later tended to be the highest yielding plots. Longer periods of pod development [days from stage R2 (flowers at top node) to R4] tended to be associated with lower yields. The three locations which also included fertility variables showed that differences in the P and K fertility levels utilized did not influence the number of days between any two developmental stages. These findings provide breeders with another potential selection criterion and production researchers with a better understanding of how environmental and production practice differences influence soybean yields.
Response of Onions to P Placement1
Authors: Mulkey J. R. , Albach E. L. , Dainello F. J.
Published: July 2010

Considerable variation in seedling size, vigor, and plant development occurs in onions (Allium cepa L.) where phosphate fertilizers are surface‐applied and incorporated prior to planting. Our objective was to determine the influence of P rates and placement techniques on the growth and development of fall‐seeded onions. During the fall of 1975 and 1977, two rates of P (21.8 and 43.6 kg/ha) were banded at planting at 0, 2.5, 5, 7.5, 10, and 15 cm directly below the seed and at 0, 2, 4, 6, and 8 cm laterally from the seed at a constant depth of 5 cm. The soil was a Aridic calciustoll, fine, mixed hyperthermic. Seedling growth and P uptake by onions were enhanced when P was applied in a band directly below the seed at a depth of 2.5 cm. Maximum yield was obtained when P was applied directly below the seed row at a depth of 2.5 to 7.5 cm. Yield was influenced more by P placement than rate of application. Maturity was effected by both depth and lateral placement of P. This experiment has shown that precise vertical and lateral placement of P must be achieved for optimum growth and development of onions.
Root Morphology and Early Development of Maize at Varying Levels of Nitrogen1
Authors: Maizlish N. A. , Fritton D. D. , Kendall W. A.
Published: July 2010

Organization of root growth information for maize (Zea mays L.) indicated a lack of data on the N response of make roots. Thus, the objective of this study was to quantify the morphological response of maize roots to N.

Growth chamber and field studies were conducted. Field‐grown maize was sampled during the 4 weeks after emergence to evaluate differences between field and growth chamber data. Numbers of seminal roots and lengths of the seminal root system did not increase substantially after 8 days. The nodal root system increased exponentially from 1.6 m at 8 days after emergence to 21 m at 29 days after emergence. Using the slant‐board culture technique, maize plants grown in a growth chamber received 0, 21, 42, 105, or 210 ppm total N from 50% Noagland solutions. Six plants of each treatment were harvested at 3, 10, or 17 days after emergence. Total root length of maize grown at the highest N level increased exponentially from 1.7 m at 3 days after emergence to 148 m at 17 days after emergence. Root apices increased from 111 to greater than 2,900 during the same period. Primary root (axis) numbers per plant increased with increasing N, but the elongation rate of an individual axis did not respond strongly to increased N. Frequency of laterals increased slightly as N was increased, but first order lateral elongation rate increased more strongly with increasing N. Response of shoot dry weight, root dry weight, shoot to root ratios, and leaf area to N paralleled the morphological response of roots to N. It was concluded that a growth equation which incorporates a function similar to a Michaelis‐Menten equation could accurately represent root length and root initiation as a function of time and N level.
Foliar Fertilization of Soybeans: Absorption and Translocation of 15N‐Labeled Urea1
Authors: Vasilas B. L. , Legg J. O. , Wolf D. C.
Published: July 2010

Asbtract

Foliar fertilization offers a possible means of increasing soybean (Glycine max (L.) Merr.] yields, but little is known of the utilization efficiency of foliar‐applied nutrients. Field experiments were conducted in 1976 and 1977 to determine percentage recovery of foliar applied 15N‐labeled urea by soybeans and translocation of 15N within the plant. Foliar treatments containing N, P, K, S or P, K, S were applied four times during growth stages R‐5 to R‐7. Urea, potassium polyphosphate and potassium sulfate were used to supply 84 + 9 + 28 + 5 kg/ha of N + P + K + S, respectively. The P, K, S treatment was similar except that urea was excluded.

In 1976, the two foliar treatments tested on the cultivar ‘Williams’ did not result in a significant increase in seed yieId over the control value of 3,294 kg/ha. In 1977, using the cultivar ‘Kent,’ the N, P, K, S treatment resulted in a significant yield increase of 1,045 kg/ha over the control value of 3,203 kg/ha. Results from the P, K, S treatment, although consistently higher than control values, were not significantly different at the 5% level in either year. Of the total 15N applied, 44 and 67% were recovered in the plants in 1976 and 1977, respectively. Approximately 94% of the recovered 15N ultimately was found in the seed. A maximum of 0.7 kg/ ha of the fertilizer N was translocated to the roots.

In a separate experiment, (15NH4)2SO4 was sidedressed at the rate of 112 kg N/ha at weekly intervals to different experimental units during late R‐4 to R‐7 stages. The uptake of 15N decreased from 39 kg/ha with the first application to 19 kg/ha with the last application, but the rate of 15N uptake did not change appreciably with time. Total N in the plants was not influenced by the (15NH4)2SO4 applications. The data indicated that changes in the rate of nutrient absorption by roots during pod‐fill were minimal and unlikely to be a major factor in determining the effectiveness of foliar fertilization.
Comparison of N Fertilizers for No‐Till Corn1
Authors: Bandel V. A. , Dzienia Stanislaw , Stanford George
Published: July 2010

Little is known about the relative effectiveness of granular (UG) or prilled urea (UP), urea‐ammonium nitrate solutions (UAN), and ammonium nitrate (AN) when top dressed for no‐till corn. In most of the field studies reported, the N‐fertilizer used with no‐tillage has been ammonium nitrate, ammonium sulfate, or ammonium‐based mixed fertilizers. We conducted field experiments for 3 years on three moderately well‐drained Mattapex, Bertie, and Delanco silt loam soils (all Aquic Hapludults), comparing topdressed UG, UP, UAN solution (30% N), and AN at four N rates (45, 90, 135, and 180 kg/ha) on yields of continuous corn (Zea mays L.). A zero N plot was included in each of the four replicates. Yields were significantly higher from AN than from other N sources in 1978 at Forage Farm and in 1976 and 1978 at Wye Institute. Average yield from UAN exceeded that from UP and UG at Wye Institute. In 1978, when rainfall was above normal, even at the highest rate of N (180 kg/ha) total N uptake was barely sufficient to obtain maximum yields at Forage Farm and Poplar Hill and was clearly inadequate at Wye Institute. With 180 kg/ha of N applied, N%TDM when grain had reached the dough stage was about 0.9 at Wye Institute and 1.1 at the other sites. Values associated with estimated maximum yields generally exceed 1.2%. In 1978, estimated recoveries of applied N were higher from AN than from the other N sources at Wye Institute and Forage Farm.
Interaction of Planting Date and Fall Fertilization on Winter Barley Performance1
Authors: Knapp W. R. , Knapp J. S.
Published: July 2010

Winter survival is a major limiting factor for winter barley (Hordeum vulgare L.) production in northern areas of the U.S. This field study was conducted on a Honeoye‐Lima silt loam soil (Glossoboric Hapludalf, fine loamy, mesic) to determine the effects of planting date and fall fertilization on winter survival and crop performance in the northeastern U.S. In 1975, ‘Schuyler’ barley was planted in central New York on 8 dates ranging from 21 August to 24 October. In 1976, five plantings of ‘Jefferson’ barley were made from 31 August to 14 October. On each date, treatments of 0 N and 0 P, 22 kg/ha N and 0 P, 0 N and 20 kg/ha P, and 22 kg/ha N and 20 kg/ha P were band‐applied to the soil at planting. A uniform application of 75 kg/ha K was disked into the seedbed prior to planting. At harvest, measurements were taken for grain yield, plant height, grain moisture, test weight, and components of grain yield. Grain yields were highest from early to mid‐September plantings. Winterkilling increased greatly and yields declined as planting was delayed into October. Phosphorus was necessary for best winter survival and highest grain yields. An increase in number of spikes per area was the major reason for increased yield with both P fertilization and proper planting time. Timely planting and P fertilization also increased grain test weight and hastened plant development and grain maturation. Significant interactions between planting date and fertilization were measured for grain yield, test weight, grain moisture, and spikes/m2; as planting date was delayed the need for P fertilization became greater. Nitrogen alone had no effect on barley performance when compared to no fertilizer, and N plus P produced results similar to P alone.
Double and Monocropped Wheat and Soybeans Under Different Tillage and Row Spacings1
Authors: Crabtree R. J. , Rupp R. N.
Published: July 2010

In wheat [Triticum aestivum (L.) Thell] producing regions with adequate frost‐free days to permit double‐cropping, water is often the most limiting factor in producing the second crop. To more fully utilize climatic resources and land after the harvest of wheat grain, a field study was conducted on a Wynona silty clay loam (Cumulic Haplaquolls) to analyze the effects of tillage and row spacings on soil water content and yields of monocropped (MC) and double‐cropped (DC) wheat and soybeans [Glycine max (L.) Merr.].

Double‐cropped wheat (DCW) yielded 2,210 compared to 2,530 kg/ha for monocropped wheat (MCW). Conventional tillage double cropped soybeans (CT‐DCS) in 50‐cm rows yielded 1,610 compared to 1,460 kg/ha in 75‐cm rows. No‐tillage double‐cropped soybeans (NTDCS) in 50‐cm rows yielded 1,730 compared to 1,550 kg/ ha in 75‐cm rows. Conventional tillage monocropped soybeans (CT‐MCS) in 50‐cm rows yielded 2,010 compared to 1,880 kg/ha in 75‐cm rows.

Water content in 120 cm of soil profile was not significantly affected during the soybean growing period by tillage and row spacings; however, lack of moisture in the soil‐seed environment resulted in poorer stands and lower yields for CT‐MCS in 1976. Water storage efficiency under wheat from the fully ripe stage of growth to late September averaged 28% for MCW. More grain production and more effective use of annual precipitation and soil stored water were achieved when wheat and soybeans were DC.
Development of a Model for Use in Maize Replant Decisions1
Authors: Johnson R. R. , Mulvaney D. L.
Published: July 2010

Reduced stands after planting may force maize (Zea mays L.) producers to consider the feasibility of replanting. The objective of this research was to develop guidelines for replanting decisions based on planting date, hybrid maturity class, population density, and plant distribution. Maize was planted at central and northern Illinois locations in 3 successive years. In each experiment adapted and early season hybrids were planted at three dates ranging from late April through early June. Plots were thinned to final densities of 30,890; 41,180; 51,480; and 61,780 plants/ha. The three lower densities were distributed uniformly within the row, with small gaps ranging from 0.42 to 0.85 m long, and with large gaps 1.5 m long.

Adapted hybrids tended to yield more than early season hybrids when planted before 20 May, but the overall effects of hybrid maturity class were minor. Regression analysis indicated that the optimum planting date was near 6 May, and planting either 2 weeks before or after 6 May reduced yields by less than 5%. However, a rapid decrease in yield due to planting date occurred when planting was delayed past 20 May. Averaged across environments, the interaction of planting date with density and plant distribution was not significant. Before mid May the major factors to consider in replant situations are density and plant distribution within the row. After mid May, calendar date increases in importance. A model for uniformly spaced plants is presented that predicts yield on the basis of planting date and population density. Compared to uniform spacing within the row, small gaps reduced yield by an average of 1.9% while large gaps reduced yield by 5.4%.
Effect of Soil Compaction on Yield and Water Use Efficiency of Rice in a Highly Permeable Soil1
Authors: Singh N. T. , Patel M. S. , Singh Rachhpal , Vig A. C.
Published: July 2010

Much irrigation water used in growing lowland rice (Oryza sativa L.) is lost through percolation, especially in highly permeable soils. Soil treatments to minimize water loss have been costly and laborious. We tried soil compaction as a simple and inexpensive method to cut down on percolation losses in field plot on a Fatehpur loamy sand (Typic Ustochrept) and measured crop yield and water use efficiency as a result.

The treatments consisted of soil compaction with 2, 6, 10, and 16 passes of a 130 cm wide, 0.7 metric ton stone roller when the soil was close to Proctor optimum moisture content (approximately 11.9%). With the respective treatments, we achieved a bulk density of 1.70, 1.75, 1.79, and 1.84 g/cm3 in the surface 6 cm of the soil. Rice was both directly seeded and transplanted. Soil compaction significantly reduced the water intake rate. Between the treatments of 2 and 16 passes of the roller, 99 cm of water was saved in the direct‐seeded crop. Soil compaction beyond 10 roller passes produced no significant reduction in rice yield in 1976. Significant yield increases ranging from 53 kg to 94 kg/ha were observed when soil compaction increased from 2 to 16 roller passes in 1977. The water use efficiency of rice also increased significantly with increases in compaction. These results suggest that soil compaction is a practical and perhaps a better method of minimizing the water requirements of rice than other methods, like mixing clays, laying of subsurface barriers, etc., in highly permeable coarse‐textured soils.
Soybean Growth and Yield as Affected by Row Spacing and by Seasonal Water Supply1
Authors: Taylor H. M.
Published: July 2010

Previous experiments have shown that soybeans [Glycine max (L.) Merr.] grown in narrow rows often out‐field those grown in the more traditional 102‐cm row spacings. Those experiments often have been conducted where early season leaf area development and synthesis rate, rather than seasonal water, control crop yield. The present research was conducted to test the hypothesis that wide row soybeans will yield as much as, or more than, narrow row soybeans during years of low seasonal water supply.

‘Wayne’ soybeans were grown in 25, 50, 75, and 100‐cm row widths at Castana, Iowa during the 1975, 1976, and 1977 growing seasons. All plots were thinned to 16 plants/m2 about 3 weeks after planting. Data were collected on leaf areas, leaf water potentials, stages of development, dry weights of plant parts, numbers of pods, root length densities, soil water contents, and yield.

There were wide differences among the 3 years in seasonal water supply for soybean growth. During 1977, a year when water supply was high, narrow row soybeans (25‐cm rows) yielded 17% more than those in the 100‐cm rows. During the 2 years with the lower seasonal water supplies, there were no significant differences in yield (P = 0.05) among the 25, 50, 75, and 100‐cm row spacings. Plants growing in the 75 and 100‐cm row widths, however, had higher (wetter) daytime leaf water potentials, grew taller, had larger leaf areas, and set more pods than those growing in the 25‐cm rows.

An intriguing question remains about the reason that the wide row plants yielded no more than the narrow row plants during dry years.
Measurement of Matric Potential in Plant Tissue with a Hydraulic Press1
Authors: Shayo‐Ngowi A. , Campbell G. S.
Published: July 2010

In order to determine the suitability of using a simple hydraulic press for matric potential measurements on plant tissue, measurements made with the hydraulic press were compared with measurements made using a pressure chamber. Leaf tissue from Phalaris arundinacea, Rhus glabra, Pinus ponderosa, Triticum aestivum, and Zea mays was pretreated by freezing and thawing to destroy membranes, so only the matric component of the potential was measured. The samples were then dried for varying lengths of time and matric potentials were measured with the pressure chamber and the hydraulic press. Correlations of measurements on the five species showed slopes which did not differ significantly from 1, intercepts which did not differ significantly from zero, and correlation coefficients ranging from 0.96 to 1.00. The hydraulic press method is faster and easier than the pressure chamber, and required equipment is less expensive.
Performance and Economic Returns of Beef Cows and Calves Grazing Grass‐Legume Herbage1
Authors: Petritz D. C. , Lechtenberg V. L. , Smith W. H.
Published: July 2010

abstract

A 3‐year grazing study was conducted to evaluate tall fescue (Festuca arundinacea Schreb.), orchardgrass (Dactylic glomerata L.), and a mixture of tall fescue and clover (Trifolium sp.) as beef cow pasture. The purpose of the study was to determine the relative animal performance and economic returns from the three pasture swards when grazed by beef cows and their calves. The experiment was conducted at the Southern Indiana Purdue Agricultural Center on a site consisting of Zanesville silt loam (Typic Fragiudalf). The grass pastures were fertilized with 112 kg/ha N each year. All pastures were grazed from late April until early October.

Calf gains averaged 0.80, 0.54, and 0.83 kg/day on orchardgrass, tall fescue, and tall fescue‐legume pastures, respectively. Cow gains averaged 0.26, 0.01, 0.26 kg/day and conception percentage averaged 90, 71, and 92 on the orchardgrass, tall fescue, and tall fescue‐legume pastures, respectively.

Economic benefits were assessed by calculating the differences in receipts and production costs associated with the various pastures. Tall fescue‐legume pastures produced $106/ha greater net returns than tall fescue pastures, and $8/ha greater net returns than orchardgrass pastures. Most of the difference in net returns was due to poor calf gains and poor conception percentages when the animals were grazing tall fescue pastures.
Mineral Concentration of Tall Fescue Genotypes Grown under Controlled Conditions1
Authors: Sleper D. A. , Garner G. B. , Nelson C. J. , Sebaugh J. L.
Published: July 2010

Grass tetany is a disease affecting cattle, sheep, and goats when limited amounts of ultilizable Mg are available. Genetic and environmental considerations on forage Mg are critical if agronomists are to provide forages with low tetany potential. Two genotypes of tall fescue (Festuca arundinacea Schreb.) that differed in inherent Mg concentration were grown in controlled environments to determine if growth temperature and interval between harvests could overcome genetic influences on Mg concentration. Vegetative herbage of genotype B5‐62 had Mg concentrations of 0.38 and 0.290%, at the high (25/20 C day/night) and low (17/12 C day/night) temperature, respectively. Genotype B17‐42 was inherently low in Mg concentration, and had values of 0.22 and 0.14% for the high and low temperature, respectively. Calcium concentration and the K/(Ca+Mg) ratio were little influenced by the two temperature treatments. Genotype B5‐62 was well below the 2.2 (meq/100 g dry matter) critical level for the K/(Ca+Mg) ratio, while B17‐42 was above for most treatments. Interval of harvest significantly altered onlv the concentration of K and the K/(Ca+Mg) ratio, with both being the lowest from treatments that were harvested less frequently. It was concluded that genetic control for Mg concentration in these genotypes was sufficiently strong so that genotypes selected for high and low Mg remained relative over two growth temperatures and three harvest intervals.
Soil Submergence Effects on Nutrient Uptake, Growth, and Yield of Five Corn Cultivars1
Authors: Singh Room , Ghildyal B. P.
Published: July 2010

The potential of new corn hybrids in India is not obtained because of waterlogging. A field experiment on a Mollisol‐udoll soil was conducted 1) to study the response of five corn varieties (cultivars) to waterlogged conditions and 2) to determine the critical growth stages and duration of waterlogging at which yield is significantly reduced. Waterlogging affected growth rate, nutrient uptake, a number of other physiological processes, and yield.

Waterlogging (48 hours and 72 hours) at knee‐high stage and tasselling stage retarded the growth of all the varieties except ‘Ganga‐2’ and submergence for 72 hours significantly reduced the uptake of N and K and increased P uptake in all the varieties. Calcium and Mg uptake were unaffected.

The grain yield of varieties was found in the decreasing order of ‘Jaunpur’ < ‘Kisan’ < ‘Vijay’ < ‘Ganga‐7’ < Ganga‐2. Soil flooding at knee‐high stage was found to be more harmful than at tasseling stage. The critical limits of waterlogging at knee‐high stage were 72 hours for Ganga‐2 and 48 hours for other varieties. Flooding for 72 hours did not reduce the yield of Ganga‐2 at tasselling stage but yield of other varieties was significantly decreased. Ganga‐2 was more tolerant to waterlogging because it developed maximum gas spaces and an extensive adventitious root system at the surface of the water under waterlogged conditions.
Mineral Concentration in Two Tall Fescue Genotypes Grown under Variable Soil Nutrient Levels1
Authors: Brown J. R. , Sleper D. A.
Published: July 2010

Grass tetany is a disease that affects cattle and sheep. Information is needed to determine if soil treatments can alter mineral concentration in the herbage. Two tall fescue genotypes (Festuca arundinacea Schreb.) B17‐42 and B5‐62, which differ in their genetic ability to accumulate Mg were grown under different K and Mg levels in the greenhouse. Experiments were conducted to test the hypothesis that the genetic differences to accumulate Mg could be altered by soil fertility treatments. Potassium was added at a rate of 50, 150, and 250 ppm while Mg was added at a rate of 0, 90, to a Mexico soil (Udollic Ochraqualf) and 230 ppm to a Keeno soil (Mollic Fragiudalf) growing both tall fescue genotypes. Genotype B5‐62 had the highest Mg concentration for all treatments. Genotypes growing. on the Mexico soil contained more herbage Mg than those growing on the Keeno soil. Initial soil tests showed that the Mexico soil contained 234 ppm of Mg while the Keeno soil contained only 73 ppm Mg. Applied K or Mg soil treatments did not eliminate the ability of B5‐62 to accumulate more Mg than B17‐42.
Shattercane Control in Narrow‐Row Soybeans1
Authors: Burnside O. C.
Published: July 2010

Much shattercane [Sorghum bicolor (L.) Moench] infested land is being rotated from sorghum [Sorghum bicolor (L.) Moench] or corn (Zea mays L.) to soybeans [Glycine max (L.) Merr.] in order to selectively control this weed increaser with herbicides plus cultivation. Some farmers became interested in growing these soybeans in narrow‐rows and eliminating cultivation in order to take advantage of higher yields of drilled soybeans. Thus, field experiments were designed to determine the feasibility of narrow‐row soybean production on a Colo silty clay loam (Cumulic Haplaquolls) infested with a forage sorghum [Sorghum bicolor (L.) Moench] during 1974‐78 at Lincoln, Neb. Forage sorghum showed competitiveness similar to shattercane without soil persistence of seed, and preplant herbicides were selected for shattercane toxicity and soybean tolerance. Seven of 18 herbicide treatments applied preplant and soil‐incorporated gave better than 95% average weed control, but none gave 100% control. Many preplant herbicides selectively controlled weeds in soybeans with little or no soybean injury or stand loss. These same herbicides facilitated economical, narrow‐row soybean production without cultivation in shattercane infested fields. However, a limited amount of shattercane seed was produced each year; so some method of controlling these weed escapes will be needed if shattercane is to be eradicated from soybean fields.
Root Temperature and Percentage NO3−/NH4+ Effect on Tomato Plant Development I. Morphology and Growth1
Authors: Ganmore‐Neumann Ruth , Kafkafi U.
Published: July 2010

The increased use of combined irrigastion and fertilization under field conditions, and the possibility of sup plying nutrients to the plants daily raised the problem of the best percentages NO3‐/NH4+ to be supplied to tomato plants (Lycopersicum esculentum Mill) grown in the field in the various seasons. The objectives of this work were to find the most suitable percentages of NO3‐/NH4+ at various root temperatures, on growth and morphology of tomato roots.

Tomato plants were grown in an experiment with a factorial design of four temperatures (8, 16, 24, and 34 C) and four percentages NO3‐/NH4+ (100/0, 75/25, 50/50, and 0/100) at constant N concentration of 10 meq/liter and constant pH of 6.5. To maintain the percentage NO3‐/NH4+ and pH constant, the nutrient solution was flushed through the pots at a rate of 1 liter per hour. When constant pH and constant solution composition were maintained the 50/50 NO3‐/NH4+ treatment showed the most growth, averaged over all temperatures. High percentage NO3‐/NH4+ retarded plant growth at low root temperatures but is preferred at high root temperature. Plants grown in solution rich in NO3‐ developed long, thin branched roots and those grown in solution rich in NH4+ developed short, thick second and third order roots.

The results of this work can be directly applied to hydroponic systems and with a future field study it may produce new fertilizer solution compositions to be adapted to specific soil environmental conditions.
Applied N and Moisture Level Effects on Yield, Depth of Root Activity, and Nutrient Uptake by Soybeans1
Authors: Al‐Ithawi Bashir , Deibert E. J. , Olson R. A.
Published: July 2010

The soybean [Glycine max (L.) Merrill] has commonly been recognized as a rather non‐responsive crop to fertilizer treatments compared with cereals, reasons for which are quite obscure. For studying the moisture and nutritional aspects that might be involved in this anomaly, a field experiment was conducted on Sharpsburg silty clay loam, a Typic Argiudoll, at three moisture levels, with three depths of 32P tagged P placement (22.5, 45, 90 cm) during 1974 and 1976. Objectives were to evaluate effects of fertilizer N, residual soil N, and moisture level on yield, zones of root activity, water use efficiency, and the total uptake of N, P, K, Ca, Mg, Fe, Cu, and Zn by the crop.

Seed yield of soybean was increased 675 and 1148 kg/ha by high soil moisture levels compared with low levels in 1974 and 1976, respectively. Total dry matter, percent plant P derived from fertilizer and uptake of all nutrients were also increased with increased soil moisture level. Although placement depth of 32P‐tagged P had no effect on total dry matter accumulation and seed yield of soybean there was essentially equivalent utilization of the tagged fertilizer whether placed at 22.5, 45, or 90 cm depth evidencing the deep nutrient extraction capabilities of the soybean plant. Nitrogen fertilizer significantly increased seed yield of soybean at all moisture levels in 1974 but only at low moisture in 1976 with amounts of residual soil NO3‐N at planting explaining the difference between the 2 years. Applied N also increased removal of all other soil nutrients measured except Fe. Consumptive water use was greater the higher the rate of N applied and the higher the moisture regime.
Response of Sunflower to Plant Population1
Authors: Robinson R. G. , Ford J. H. , Luenschen W. E. , Rabas D. L. , Smith L. J. , Warnes D. D. , Wiersma J. V.
Published: July 2010

The cost of hybrid sunflower (Helianthus annuus L.) seed provides an incentive for reducing planting rates which, in turn, reduce plant populations. This research was undertaken to determine minimum populations needed for maximum yield and their effect on seed quality and head drying. Populations of oilseed and nonoilseed cultivars of 17, 25, 37, 49, and 62 thousand plants/ha were established at six locations in Minnesota. Soils were Typic Haplaquolls, Aeric Calciaquolls, Typic Eutroboralf and Udorthentic Haploborolls. Both oilseed and nonoilseed cultivars required the same populations for maximum yield. Minimum populations needed for maximum yield varied from 25 to 62 thousand plants/ha among locations. Differences in optimum plant populations among locations were attributed to soil, rain, and temperature. Yields were not depressed by populations up to 62 thousand. Optimum population for oilseed and small‐nonoilseed cultivars was that which gave maximum yield because seed quality factors of test weight and/or oil percentage increased with population. Optimum population for large‐nonoilseed cultivars was often less than that giving highest yield because the percentage of large seeds decreased with increasing population. As plant populations increased from 17 to 62 thousand plants/ha, head moisture percentages decreased from 68 to 50% at early harvest and from 43 to 20% at later harvest. Preharvest desiccant sprays reduced head moisture but did not alter the relationship between increasing population and decreasing head moisture. Increasing row spacing to conserve soil moisture between rows did not increase yield on a sandy soil.
Planting Date Effects on Growth, Yield, and Oil of Irrigated Sunflower1
Authors: Unger Paul W.
Published: July 2010

Interest in sunflower (Helianthus annuus L.) as an oilseed crop has greatly increased in the Southern Great Plains since 1974. To effectively manage sunflower for oil production and oil quality, information is needed concerning the effect of various agronomic practices. The objective of this research was to determine the effect of planting date on growth, yield, oil percent, and oil fatty acid concentration of irrigated sunflower. Sunfower ‘Hybrid 896’ seed was planted at about 2‐week intervals from late March to late July or early August from 1975 to 1978 on Pullman clay loam (fine, mixed, thermic Torrertic Paleustoll). Time from planting to emergence was influenced by soil temperature, and ranged from 19 days with early plantings to 5 days with late plantings. The time from planting to the 50% ray flower stage decreased with delayed plantings, except for the last four plantings for which the average was about 59 days. Seed yields were not significantly different with plantings from late March to mid‐June. Yields decreased with plantings after 21 June. Seed soil percent was relatively constant with early plantings, but decreased with plantings after about 29 May; oil yield/ha also decreased with plantings after that date. The oleic and linoleic acid concentrations of the oil were strongly affected by planting date because the different planting dates resulted in seed development during periods of different temperatures. Earlyplanted sunflower matured during hot weather, and the oil had oleic and linolecic acid concentrations of 43 and 45%, respectively. Oil from late‐planted sunflower, which matured during cooler weather, had oleic and linoleic acid concentrations of around 15 and 75% respectively.
Imbibitional Chilling Injury in Soybean Axes: Relationship to Stelar Lesions and Seasonal Environments1
Authors: Ashworth E. N. , Obendorf R. L.
Published: July 2010

The increasing use of isolated embryonic axes as experimental tissues for studies on early germination events warrants an evaluation of stress effects during hydration. The objectives were to evaluate embryonic axis growth and stress crack formation in soybean (Glycine max (L.) Merr.) seeds and isolated axes resulting from hydrational stresses of cold temperatures and low tissue moisture. Sensitivity to imbibitional chilling of seeds and isolated axes was evaluated in several cultivars produced in different years at different locations. Germination, seedling growth, and formation of stelar lesions were measured. Isolated axes with an initial moisture content of 6% were injured by imbibition at 5 C as evidenced subsequently by reduced growth at 25 C. Adjustment of axis moisture to 17% before hydration protected against imbibitional chilling injury. Sensitivity to imbibitional chilling was influenced by cultivar and year or location of production. Lesions formed across the stele of hypocotyls during rapid hydration of 6% initial moisture isolated axes at 5 or 25 C but were not observed after hydration of 17% moisture axes or after hydration of intact seeds. The presence of lesions suggests caution when using isolated embryonic axes as experimental tissues.
Use of Deterministic and Empirical Models to Predict Potential Evapotranspiration in an Advective Environment1
Authors: Shouse Peter , Jury W. A. , Stolzy L. H.
Published: July 2010

A field experiment was conducted for three successive summers in the arid southwestern United States to determine the applicability of traditional empirical and deterministic potential evapotranspiration formulas for predicting water loss under extreme advective conditions. Five models for predicting potential evapotranspiration were compared to hydrologic balance estimates of water loss from a cowpea (Vigna unguiculata L. Walp) crop over two summer seasons and to each other during a third summer season. Of the five methods, pan evaporation was the least reliable indicator of full‐cover crop water use whether considered on a weekly or seasonal basis. The Priestley‐Taylor correlation, which required local calibration could not describe extreme changes in sensible heat advection from year to year with a single calibration. A form of the solar radiation correlation which contains parameters that are functions of humidity and wind run, worked adequately in all years as did an advection‐modified Priestley‐Taylor equation which requires a single calibration and vapor pressure deficit values. The Penman combination equation, which did not require local calibration, corresponded most closely to measured values. All models which contained some facility for recalibration or correction in response to changes in vapor deficit worked adequately under changing advective conditions during the entire experiment.
Germination and Emergence of Russian Wildrye Seeds Coated with Hydrophilic Materials1
Authors: Berdahl J. D. , Barker R. E.
Published: July 2010

Most forage grasses have a small caryopsis that must be seeded at shallow depths to emerge. However, soil surrounding the seed often becomes too dry to support germination and seedling development. Agar, alginic acid, carragheenan, ‘Super Slurper’, and ‘Viterra 2 Hydrogel’3 were incorporated into silica seed coatings of Russian wildrye (Elymus junceus Fisch.) to increase the quantity of water available to the germinating seed and seedling. After 72 hours, water uptake from a saturated blotter averaged 4.3 mglseed for a silica coated check and ranged from 5.6 to 9.0 mglseed for the five hydrophilic coatings. At 14 days, seed germination was 95.5% for an uncoated check and ranged from 86.5 to 93.5y0 for the five hydrophilic coatings. Vermiculite was ground to pass a 1.0‐mm screen, and water was mixed with the vermiculite to obtain matric potentials of −1, −5, −9, −10, −11, and −12 bars. None of the seed coatings increased the rate of emergence or increased the total emergence relative to the uncoated check within any of the six matric potentials. Failure of any of the five seed coatings to improve seedling emergence from vermiculite over a wide range of matric potentials suggested that hydrophilic coatings have little potential to improve stand establishment of Russian wildrye in the field.
Influence of Soil Compaction on Three Turfgrass Species1
Authors: Carrow R. N.
Published: July 2010

Wear and soil compaction from foot and vehicular traffic are major stresses on recreational turfgrass areas. Few investigations have been conducted on turf where only soil compaction stress was applied. In this field study the influence of soil compaction on morphological and physiological aspects of three turfgrass species was investigated. The cool season turfgrass species (Lolium perenne L. ‘Pennfine’; Poa pratensis L. ‘Baron’; Festuca arundinacea Schreb. ‘Kenutcky 31’) were subjected to three compaction treatments with a smooth, power roller: 1) O× — none except routine mowing, 2) 12× — 12 times a week for 8 weeks, 3) 24× — 24 times a week for 8 weeks. A fine, montmorillonitic mesic Aquic Arquidoll soil was used.

Visual quality, percent turf cover, and total nonstructural carbohydrate (TNC) declined for all species as compaction stress increased. Eight months after compaction ceased, tall fescue and Kentucky bluegrass still exhibited reduced visual quality and percent cover.

Shoot density, verdure, and root growth also were affected by compaction, with response differing by species. Increased compaction reduced verdure, shoot density, and root growth of Kentucky bluegrass; decreased verdure for tall fescue; but perennial ryegrass exhibited no adverse effects except some reduction in root weight at the 12× treatment.

Compaction tolerance differences among species were determined using the growth parameters measured. With aeration porosity at −0.10 bar water content and bulk density as measures of soil compaction, visual quality rating and percent turf cover gave the best compaction tolerance differentials among species. Species tolerance to compaction, when based on those factors, was perennial ryegrass = Kentucky bluegrass > tall fescue.
Sulfur Diagnostic Criteria as Affected by Age and Defoliation of Subclover
Authors: Jones M. B. , Ruckman J. E. , Williams W. A. , Koenigs R. L.
Published: July 2010

Sulfur deficiencies are widespread in California annual grasslands and in other areas of the world where subclover (Trifolium subterraneum L.) is an important legume. Intensive grazing is often practiced where subclover is grown. Therefore, to determine the need for S fertilization it is important to know how defoliation and plant age influence the diagnostic tissue tests used to assay subclover S status.

Subclover was grown on S−deficient soil (Josephine, fine−loamy, mixed mesic, Typic Haplozerults) with six levels of applied S and four clipping treatments in a greenhouse. Four criteria for assaying S status were used: total S, sulfate S, sulfate S/total S ratio, and N/S ratio in the three youngest fully expanded leaves required to give 90% of maximum yield (critical levels based on Mitscherlich functions).

The critical levels of sulfate S/total S and N/S ratios were the most stable over plant age and clipping frequency. Both assays accounted for about three−quarters of the variation on the average.

The critical levels of total S and sulfate S although associated with over 90% of the variation were not stable individually, decreasing from 0.20 to 0.08% S and from 220 to 140 pprn sulfate S at 60 and 133 days from planting, respectively. Clipping frequency caused considerable variation in the critical levels for total S and sulfate S assays, making them more difficult to interpret than the sulfate S/total S and N/S ratio assays.

It was concluded that the sulfate S/total S ratio has some advantages over the other assays, such as stability through the growing season, being little affected by defoliation, and resulting from a single analytical regime.
A New Look at Row and Broadcast Phosphate Recommendations for Winter Wheat1
Authors: Peterson G. A. , Sander D. H. , Grabouski P. H. , Hooker M. L.
Published: July 2010

Phosphate fertilizer recommendations for winter wheat have traditionally been in terms of doubling the row applied P rate if broadcast application is to be used. A literature search failed to locate a significant amount of supportive data for this practice.

The experiments reported here were conducted to determine if there is a consistent relationship between broadcast and row applied P rates for winter wheat and if so, what that relationship is.

Six field experiments were conducted over a 2 year period on soils of, the Typic Argiustoll subgroup. Treatments were five rates of 0‐46‐0 (0, 11, 22, 34, 45 kg P/ha) applied as either preplant broadcast or drilled with the seed.

All experiments were on soils that responded positively to P fertilization. Results contradicted the concept of a 2:1 ratio of broadcast to row P application as standard practice. The relative effectiveness of row and broadcast methods changed with changing soil tat P levels. Low soil test locations exhibited an effective ratio of about 3:1 while medium soils tests had ratios of 1:1.