bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical Retardation of Bermudagrass Turf1
Authors: Chu‐huang Wu , Myers H. R. , Santelmann P. W.
Published: July 2010

Little information is available on the influence of chemical growth regulators on warm season perennial turf grasses. Therefore, greenhouse and field experiments were conducted to evaluate several such compounds for their potential in retarding the growth of common and ‘Sunturf’ bermudagrass [Cynodon dactylon (L.) Pers]. Maleic hydrazide [ 1,2‐dihydro‐3,6 pyridazinedione (MH)] and chlorflurenol [Methyl‐2‐chloro‐9‐hydroxyfluorene‐9‐carboxylate (CF)] injured both types when applied at 4.5 or 3.4 kg/ha in the greenhouse. Ethephon (2‐chloro‐ethylphosphonic acid) stimulated stem elongation of both bermudagrasses when applied at rates below 6.7 kg/ha in the greenhouse, while higher concentration retarded their growth in the field. Greenhouse plants grown under a wet regime (watered daily) showed no significant difference in chemical retardant effects on plant top growth and internode length from those grown under a dry (watered every three days) regime. Although more plant growth did occur in wet regimes, the growth retardation effect by the chemicals was not nullified by such conditions. Common bermudagrass was less susceptible to injury than Sunturf in the greenhouse, and no significant retardation of Sunturf top growth was obtained in the field. Fluoridamid (N[3‐[(1,1,1‐trifluoromethylsulfonyl) amino]4‐methylphenyl]acetamide), MBR 12325 (N‐[2,4dimethyl‐5‐[ trifluoro‐methyl)‐sulfonyl] ‐amino]‐phenyl acetamide), MH, CF, and ethephon were effective in reducing bermudagrass vegetative growth and seedhead development in the field. Single high rates of these compounds frequently caused bermudagrass injury, while split applications or chemical combinations at low rates provided excellent growth retardation with no undesirable turf appearance.
Some Interactions in Plants Among Cadmium, Other Heavy Metals, and Chelating Agents1
Authors: Wallace A. , Romney E. M. , Alexander G. V. , Soufi S. M. , Patel P. M.
Published: July 2010

Four experiments were conducted under glasshouse conditions with either soil or solution culture to evaluate interactions of Cd among other mineral elements in plants when yields are decreased by Cd as can happen under conditions of contamination. Chelating agents were included in the study because of their uses in plant nutrition and because they are known to increase uptake and translocation differentially of trace metals. Bush beans (Phaseolus vulgaris L. var. ‘Improved Tendergreen’) were grown with 10−6, 10−5 and 10−4M Cd in solution culture. Vegetative yields were depressed in the presence of Cd; 10−4M produced the greatest reduction (61%). The Cd concentration in plants was roots > stems < leaves. All levels of applied Cd significantly depressed the Mn concentration in leaves, stems, and roots. This, was the most prominent interaction. In a test with Yolo loam soil (Typic Xerorthents, fine‐loamy, mixed, slightly acid, thermic) with bush beans, Cd was applied at 0, 50, and 100 μg Cd/g soil as CdSo4. Each level was interacted with either NTA (nitrilotriacetic acid) EDTA (ethylenediamine tetraacetic acid) (100 μ/g soil) as Na salts. Yields were depressed substantially by 50 μ Cd/g soil only when chelating agents were also applied (36% for NTA and 48% for EDTA). The 100 μ Cd/g soil decreased yields only slightly without chelating agents (28%). Cadmium significantly decreased Mn and Cu concentrations in leaves and overcame much of the tendency of the chelating agents to increase concentrations of Mn, Cu, and Fe in plants. Zinc was decreased only on the per plant basis with the highest applied level of Cd with chelating agents. The Cd decreased the Ca and Mn concentrations in leaves of bush beans. Cadmium levels in the plants were increased by EDTA from 6 to 423 μ/g dry weight at the high Cd level. In another experiment with the same soil, diethylenetriamine pentaacetate acid (DTPA) (100 μ/g soil) increased uptake of Cd to 35 μ/g dry weight in bush beans. The interactions were similar to those with the other chelating agents. A leaf concentration of 15 μ Cd/g (dry weight basis) decreased yields of bush beans. With corn (Zea mays L. var. ‘Golden Bantam’) grown also in the same soil, the addition of 5% CaCO3 decreased yield reduction due to Cd by decreasing its uptake (by 64% for 200 μ Cd/g soll and 76% for 400 μ). A concentration of 219 μ Cd/g in corn shoots decreased yields. Caution in the use of metal chelates is indicated when soils contain significant levels of available Cd.
Herbage Yield and Chemical Composition of Switchgrass as Affected by N, S, and K Fertilization1
Authors: Friedrich J. W. , Smith Dale , Schrader L. E.
Published: July 2010

Little information is available regarding the nutrient requirements of switchgrass (Panicum virgatum L.). The objective of this greenhouse study was to examine the effect of N, S, and K fertilization on the herbage yield, N/S ratio, and herbage concentrations of N and S in leaf blade, stem (culms and leaf sheaths), and total herbage fractions of switchgrass grown to anthesis. Three rates of N (0, 224, and 448 kg/ha of N as NH4NO3 in split application), three rates of K (0, 448, and 896 kg/ha of K as KHCO3), and two rates of S (0 and 56 kg/ha of S as CaSO4) were applied in all possible combinations (18 treatments) to pots containing soil cores of switchgrass.

Dry matter yield of all herbage fractions increased significantly with each increment of N. However, for total herbage, stems, and inflorescences, yield increase with the second increment of N was dependent upon the application of S. K fertilization decreased inflorescence yield significantly at the highest rate, but did not affect dry matter yield of any other herbage fraction.

At the highest rate of N, fertilization with S increased N concentration in the leaves, decreased N concentration in the stems, decreased the proportion of the total N localized in the stems, and increased the total herbage uptake of N. When S was applied, switchgrass responded to increased N fertilization by increasing S uptake. In contrast, when S was not applied, fertilization with N caused a dilution of tissue S and also decreased the proportion of the total herbage S localized in the stems. Concentration and content of N and S decreased with the first increment of K fertilization, but there was no change with the second increment of K. Critical N/S ratios for switchgrass appear to be greater than 10:1 for herbage, greater than 12:1 for leaf blades, and greater than 8:1 for stems.
Indirect Effects of a Thatch‐Inducing Herbicide On Soil Physical Properties Under Turf1
Authors: Jansen I. J. , Turgeon A. J.
Published: July 2010

A measurable effect on soil physical properties was suspected where applications of calcium arsenate resulted in: 1) thatch formation in Kentucky bluegrass (Poa pratensis L.) turf, 2) restriction of rooting to the thatch layer, and 3) inhibition of earthworms in the underlying soil. The objective of this study was to determine the indirect effects of Ca3(AsO4)2 on the water infiltration capacity, hydraulic conductivity, moisture characteristics, bulk density and organic matter contents of surface soils from treated turfs.

The soil studied was an Aquic Argiudoll and evaluation methods included: 1) the falling‐head, flooding method for measuring infiltration in the field, 2) the constant head procedure for measuring hydraulic conductivity in the laboratory, 3) a modified procedure utilizing Tempe cells for determining soil water retention characteristics, 4) the core method for measuring bulk density, and 5) a modified Walkley‐Black method for determining organic matter content. Infiltration rate and hydraulic conductivity were lower for the Ca3(AsO4)2 treated soils than for untreated soils. Treated soils had a higher bulk density, stored less water in the 0 to 1 bar tension range, and were lower in organic matter than the untreated soils. The marked alteration of soil physical properties observed to follow Ca3(AsO4)2 treatment is significant for turf management.
Influence of Variety and Soil Applications of Ca on Development of Ca Deficiency in Tobacco1
Authors: Peedin G. F. , McCants C. B.
Published: July 2010

Some commercial varieties of the flue‐cured class of tobacco (Nicotiana tabacum L.) develop abnormalities of the buds and upper leaves which are typical of Ca deficiency. Utilizing varieties ‘Coker 254’ (susceptible) and ‘North Carolina 2326’ (slightly susceptible), a greenhouse experiment was conducted to study varietal differences in Ca accumulation and distribution, and six field experiments were conducted to determine the effect of source and level of soil Ca applications on degree of symptom development. In the greenhouse, seedlings were transplanted in sand and supplied for 31 days with solutions containing 1, 75, or 150 ppm Ca. In the field experiments, rates of 0, 28, 84, or 168 kg/ha Ca (as CaSO4) were band‐applied at transplanting; at one location and for two successive years, the variety and CaSO4 treatments were superimposed on rates of 0 and 1,121 kg/ha dolomitic limestone broadcast 2 months prior to transplanting. The soils used were classified as Typic and Aquic Paleudults and Typic Hapludults. In both the greenhouse and field, symptom expression of Ca deficiency was more pronounced on ‘C‐254’ than on ‘NC 2326’ plants, but reduction of symptom expression with increasing levels of Ca was obtained only in the greenhouse. Maximum dry weight for ‘C‐254’ was obtained with the 150 ppm Ca treatment, while the 75 ppm Ca treatment was sufficient for maximum growth of ‘NC 2326’. Conclusive evidence of varietal differences in Ca absorption was not obtained, but Ca concentrations in the apical tissues of ‘C‐254’ were substantially lower than those in apical tissues of ‘NC 2326’, indicating that absorbed Ca was distributed less effectively in ‘C‐254’ than that in ‘NC 2326’. Failure of ‘C‐254’ to maintain adequate Ca concentrations in apical tissues may be associated with its comparatively greater accumulation of dry weight and absorbed Ca in leaf than stalk tissue. In field experiments, Ca deficiency symptom development was not related to level of exchangeable soil Ca, and was not influenced by the rates of CaSO, and/or dolomitic limestone used. Rather, symptom development was less pronounced at locations where plants were subjected to prolonged periods of moisture stress during vegetative growth, indicating that Ca deficiency is more likely to develop on immature plants that undergo periods of rapid growth.
A Hand Caliper for Measuring Thickness of Soybean Pods1
Authors: McWilliams J. M. , Hatchett J. H. , Stadelbacher E. A.
Published: July 2010

A precise, quantitative measure of pod growth, applicable from early pod elongation to full‐size green beans, was needed to determine the relationship of soybean [Glycine max (L.) Merr] pod maturity to insect seed feeding damage. Since pods increase in thickness as the seeds develop, measurements of pod thickness can be used for this purpose. A “V” type hand caliper that provided direct thickness measurements of pods in increments of 0.5 mm was devised. The change in pod thickness of a determinate soybean variety was determined by measurements taken in the field at different times during pod growth. The rate of increase in thickness was not uniform but averaged 0.5 mm/4 days. Characterization of pod growth by thickness has potential for relating pod development to insect damage and may have additional application for the study of other stress factors on yield.
Sulfur Requirements of Cowpea and Implications for Production in the Tropics1
Authors: Fox R. L. , Kang B. T. , Nangju D.
Published: July 2010

Low S concentrations in rainwater and depleted organic matter reserves of soils are associated with S deficiencies in the seasonally dry West African savanna. The purpose of this study was to provide information on the internal and external S requirements of cowpea, a promising grain legume for tropical Africa. Three cultivars of cowpea [Vigna unguiculata (L.) Walp.] were grown in pots in which seven levels of SO4‐S were maintained in the soil solution. About 7 ppm S was required in the soil solution for 95% of maximum grain production for cultivars ‘TVu 76‐2E’ and ‘TVu 201‐ID’. Cultivar ‘Sitao Pole’ required about 2 ppm S in solution.

The S contents of uppermost, fully expanded leaves at early flowering associated with 95% of maximum grain yield were 0.32% for Sitao Pole and 0.50% and 0.65% for cultivars, TVu 201‐ID and TVu 76‐2E respectively. The corresponding S content in the petioles was about 0.08%, 0.39%, and 0.42% respectively. Older leaves and leaf petioles accumulated S if it was supplied in excess of requirements.

The S percentage of grain was 0.26% when yield was 95% of maximum. Sitao Pole accumulated S to a maximum of 0.36% when SO4‐S was supplied at 45 ppm in solution. About 30% of the plant S was in the grain of plants adequately supplied with S and about 50% was in the grain when the S supply was moderately deficient. The N/S ratio of upper trifoliate leaves associated with 95% of maximum grain yield was about 10 at first bloom.

At near maximum yield, cultivar TVu 201‐ID contained about 80 mg S per plant in the grain. Assuming (65,000 plants/ha) the S requirement for grain was about five times mean annual S in the rainwater of northern Nigeria.

Sulfur fertilization of field grown cowpea in southern Nigeria was accompanied by a small (12%) but statistically nonsignificant increase in yield. Sulfur fertilization (20 kg S/ha) was required to give 0.26% S in the grain.
Ratoon Cropping of Sorghum. III. Effect of Nitrogen and Cutting Height on Ratoon Performance1
Authors: Escalada Rodolfo G. , Plucknett Donald L.
Published: July 2010

The perennial habit of sorghum, Sorghum bicolor (L.) Moench, in a tropical climate permits the production of successive harvest of seed crops from an initial planting. Cultural treatments involving tillage and fertilization to favor such practice are termed ratooning. The objective of this study was to determine the effects of the various N rates and cutting heights on ratoon crops of sorghum at different seasons in relation to tillering behavior, yields, and other agronomic characteristics. Recognizing these effects would facilitate the timely application of the right amount of N fertilizer and proper cutting height to be done on ratoon crops.

The performance of ratoon crops of grain sorghum, Sorghum bicolor (L.) Moench, ‘Pride 550 Br’, was studied as affected by four N rates (0, 100, 200, and 250 kg N/ha as urea) and three cutting heights (3, 8, and 13 cm) in the field in Hawaii. Performance characteristics studied were tillering behavior, yield and yield components, plant height, days to heading and maturity, and total plant N content. One half of the N was applied when the seedlings were about 3 weeks old; the other half side‐dressed at early booting stage.

Generally, in the plant crop and ratoon crops, more tillers, larger leaf area, larger stalks, larger heads with more and heavier grains, and taller plants, and therefore, increased grain and stover yields were produced with higher N treatments up to 250 kg N/ha. Application of 100 kg N/ha increased the total plant N (percent) and further application of N (200 and 250 kg N/ha) increased the N concentrations in the plant from the first to the third ratoons. In the fourth ratoon and in Kilauea planting, total plant N did not increase despite N applications. Although yields increased as the amount of N increased, a leveling off or decline in yields at high N rates, occurred, indicating that optimum N rates were reached in this study. During winter, highest yields were produced with 200 or 250 kg N/ha and when plants were at the 13‐cm cutting height. In summer, higher yields were produced with the same N rates but lower cutting heights (3 and 8 cm).

Based on this study, it is recommended that to obtain high grain and stover yields during winter and summer, 200 to 250 kg N/ha be applied to ratoon crops harvested at 13‐cm and 3‐ and 8‐cm cutting height, respectively.
Response of Dryland Cotton Plant Growth, Soil‐water Uptake, and Lint Yield to Two Extreme Types of Tillage1
Authors: Stibbe E. , Hadas A.
Published: July 2010

Better soil management prior to dryland cotton growing is not or hardly rewarded by a higher cotton lint yield production in a semi‐arid climate. More information about the soil moisture depletion pattern of dryland cotton on different tillage practices is needed. The purpose of this study was to evaluate the influence of differences in soil‐water stress in the root zone with time as a result of tillage practices on growth and yield of a dryland cotton crop. The soil‐water interaction patterns of roots of dryland cotton (Gossypium hirsutum L.) on two extreme types of tillage practices were studied in a field experiment with six replications per tillage treatment. The two tillage practices were plowing to a depth of 40 cm and a no‐tillage disking prior to the cotton growing season. Cotton was grown in a 2‐year rotation of dryland cotton and winter wheat (Triticum aestivum L.)

Soil conditions created by the two tillage practices resulted in a denser and deeper root system of plants on plowed soil than on minimum‐tilled soil. Above‐ground vegetative growth of plants on plowed soil was more extensive and prolonged than of those on minimum‐tilled soil. Final lint yields of the crops on the two tillage treatments did not differ in the two seasons of study.

Plants on plowed soil showed an increasing extraction rate resulting in a peak moisture stress in the reproductive stage. A relative‐constant rate was found for plants on minimum‐tilled soil in the period from emergence to early plowing and a moisture‐stress‐induced termination of the vegetative growth. It was indirectly inferred that differences in growing behavior and the similarity in lint yield of plants grown on plowed and minimum‐tilled soil were related to differences in magnitude and occurrence of soil moisture stresses developed in the root zone during the vegetative and reproductive stages of the cotton plant.
Prospects of Increasing Tropical Rice Production through Ratooning1
Authors: Bahar F. A. , De Datta S. K.
Published: July 2010

Production of a rice (Oryza sativa L.) crop by ratooning is feasible under some conditions. Ratooning of rice eliminates two labor‐saving operations: raising seedlings in the seedbed and transplanting in the main field.

Field experiments were conducted for 2 years on Maahas clay (an isothermic clayey mixed Aquic Tropudalf) to evaluate the performance of rice cultivars for ratooning ability and the agronomic practices that affect ratooning. The agronomic practices studied were cutting height of the crop produced from seed (referred to as the “main” crop), N level, plant spacing, water management, and degree of land preparation.

All the cultivars that were grown as ratoon crops were infected by the grassy stunt virus disease; the same cultivars grown simultaneously by transplanting and direct seeding were not infected. That indicates the high risks of growing virus‐susceptible cultivars as a ratoon crop.
Autumn‐Accumulated Tall Fescue and Orchardgrass. I. Growth and Quality as Influenced by Nitrogen and Soil Temperature1
Authors: Archer K. A. , Decker A. M.
Published: July 2010

In many situations autumn‐saved pastures offers an excellent alternative to more traditional and expensive livestock programs where hay or silage are the main winter feeds. Environmental conditions during the period of fall forage accumulation are markedly different from those of the spring and summer months and both forage yield and quality were affected. The objective of this research was to study the effects of temperature and nitrogen fertilization on the growth and quality of autumn‐accumulated forage. Two field experiments were conducted during 1970–71 on a Beltsville silt loam soil (Typic Fragiudults) to measure the influence of N rates and soil temperatures on the growth and quality of autumn‐saved ‘Ky‐31’ tall fescue (Festuca arundinacea Schreb.) and ‘Potomac’ orchardgrass (Dactylis glomerata L.). Nitrogen was applied at either 0, 50 (1970 only), or 100 kg N/ha in late September. In 1971 soil temperatures were maintained at ambient and approximately 12, 20, and 27 C during the autumn using specially designed field equipment. Forage samples were collected from randomly‐selected, previously unharvested areas. These were separated into green, dead, and miscellaneous fractions for yield and quality evaluation. Tall fescue was a more suitable species for autumn‐saved pasture primarily due to its superior growth compared with orchardgrass. Differences in quality were not consistently found between the species. In November of each year, dry matter availability reached a maximum of approximately 4,000 and 3,300 kg/ha for tall fescue and orchardgrass, respectively. During December under ambient conditions net loss of dry matter occurred in both species, presumably due to a greater rate of leaf death and decay than leaf growth. Digestibility and protein percentages decreased only slightly during autumn. The minimum IVDMD and crude protein levels measured during approximately 100 days of accumulation in either year were 80 and 13.5% for tall fescue and 73.0 and 15.2% for orchardgrass, respectively. Nitrogen fertilization stimulated growth of the autumn‐saved pastures and also tended to increase crude protein percentages. An application of 100 kg N/ha in late summer produced up to 50% more dry matter by early winter than zero N. IVDMD of the forage was not affected by N fertilization.

Growth of the grasses during fall was stimulated by increasing the soil temperature. This effect was greater for tall fescue than orchardgrass. Plant quality was only slightly affected. However, the relative effects of the soil temperature treatments in relation to air temperatures and light parameters were not determined.
Nitrate Distribution and Variability in Irrigated Fields of Northeastern Colorado1
Authors: Ludwick A. E. , Soltanpour P. N. , Reuss J. O.
Published: July 2010

Fertilizer N recommendations in the Great Plains and Western USA are commonly based on soil NO3− tests, although NO3− content within soil profiles is subject to rapid change. The purpose of this study was to evaluate NO3− distribution within diverse soil profiles and determine NO3− changes occurring overwinter. Twenty‐six irrigated farm fields were systematically sampled in 1974 and 1975 by dividing them into 61 × 61 m grids (0.37 ha) and sampling to a 120‐cm depth by 30‐cm increments. Eleven fields were re‐sampled for fall vs. spring comparisons. Nitrate content tended to be greatest in the surface 30‐cm and decrease with depth; only three fields deviated markedly from the general pattern. Nitrate contents in the 0 to 30‐cm and 0 to 60‐cm depths were both highly correlated at the 0.01 level with that in 0 to 120 cm (r2 = 0.80 and 0.91, respectively), and actual NO3‐N content (0 to 120 cm) was within 30 kg/ha of the regression lines for 25 of 26 fields. All fields significantly increased in NO3,‐N from fall to the following spring, ranging from 8.1 to 68.9 kg/ha. Greatest increases occurred in the surface 30 cm. These increases were significantly related at the 0.05 level to decreases in NH4+ (r2 = 0.37), fall NO3− level (r2 = 0.43), and fall NO3− plus NH4+ level (r2 = 0.42), but not to organic matter or total N. There was a highly significant relation at the 0.01 level between fall ‐ and spring NO3− content of each sampled depth, ranging from r2 = 0.60 to 0.86. The above relationships should be useful in determining appropriate soil sampling depths for N fertilizer recommendations and developing calibrations based on sampling date.
Influence of Within‐row Variability in Plant Spacing on Corn Grain Yield1
Authors: Krall J. M. , Esechie H. A. , Raney R. J. , Clark S. , TenEyck G. , Lundquist M. , Humburg N. E. , Axthelm L. S. , Dayton A. D. , Vanderlip R. L.
Published: July 2010

Corn (Zea mays L.) grain yields have been related to wide range of management practices. Row spacing and plant population effects have been well documented; however, little research has been conducted on the variability of within‐row plant spacing and its effect on grain yields.

Experiments were conducted in 1972–75 at three irrigated locations in Kansas to determine the effect of within‐row variability of plant spacing on corn grain yields. Low variability was obtained by hand planting within machine planted areas which provided a range of variability. Within‐row variability of plant spacing was determined on 3‐m sections of rows by taking individual measurements between adjacent plants and calculating the standard deviation of spacing. Grain yields consistently decreased as variability of spacing increased at two of the three locations. The third location was more variable and in general showed no relationship between variability of spacing and grain yields. A survey of within‐row variability in plant spacing in fields in three Kansas counties indicated that planting precision could increase yields 200 to 1,200 kg/ha without changing planting rates.
Complementary Effect of Soil Puddling, Submergence, and Organic Matter on Rice Production1
Authors: Singh N. T. , Josan A. S. , Gupta J. P.
Published: July 2010

Puddling of soil and submergence are common practices in lowland rice (Oryza sativa L.) cultivation. Researchers, however, disagree on the merits associated with one or the other practice. Both the operations involve additional labor and water and thus deserve critical evaluation of their role in rice production. A field study was conducted on Choa sandy loam (a Typic Ustochrept) to compare the individual and combined effect of preplanting puddling of soil vs. no puddling and post‐planting soil submergence vs. soil drained to field capacity. A,n additional treatment of organic matter at the rate of 5 metric tons/ha was included to increase biological reduction of the soil. All three practices significantly increased paddy yield. An average yield of 102.2 q/ha was obtained with continued soil submergence against that of 78.5 q/ha in plots where the soil water content was maintained between saturation and field capacity. The increase in paddy yield resulting from puddling and addition of organic matter was 15 q/ha and 8 q/ha, respectively. None of the practices seemed to be a substitute for the other. In fact, the combination gave a maximum paddy yield of 105.5 q/ha during 1972 and 121.5 q/ha during 1973. Maximum drop in soil Eh was observed with the addition of wheat straw followed by soil submergence and then puddling. The uptake of iron, zinc, and manganese by 45‐day‐old plants was neither related to soil Eb nor to the paddy yield. This study shows that both submergence and puddling are desirable practices in rice culture.
Residual Effects of N Fertilization on Dryland Spring Wheat in the Northern Plains. I. Wheat Yield and Water Use1
Authors: Alessi J. , Power J. F.
Published: July 2010

Data are frequently lacking to quantify the residual effects of fertilizer applications on soil nutrient availability, especially in regions of limited rainfall. Therefore, the effects of fertilizer N on yields of continuous dryland spring wheat (Triticum aestivum L.) grown on Typic haploboroll soil were determined in a field study at Mandan, North Dakota. Rates up to 540 kg N/ha applied either (i) all in 1 year, (ii) one‐third of the total rate in each of 3 years, or (iii) one‐sixth of the total rate each year for 6 years of the experiment. Average dry matter (1967–1972) at different stages of growth and average grain yields were increased significantly by increased N rate, but only dry matter at tillering was significantly affected by rate × timing interaction. With 270 and 540 kg N/ha applied in only the first year, residual effects significantly increased grain production in 4 of the following 5 years. At total rates of 135 kg N/ha or above, total grain yield for the 6‐year period was greatest for the 6‐year fertilization treatment and least for the 1‐year treatment. Average annual grain yields for the 540 kg N/ha rates were 1,700, 1,660 and 1,880 kg/ha for the 1, 3, and 6‐year treatments, respectively, and 1,050 kg/ha for the zero‐N treatment. Weight of grain produced per kilogram of fertilizer N applied usually decreased as N rate increased. At the 135 kg N/ha rate or higher, grain production per unit of fertilizer applied was greatest for the 6‐year treatments (annual fertilization). Root weight and development in the 6th year were related to the availability of soil N as reflected by fertilizer treatment.

Total water use was significantly influenced by N rate or frequency of fertilization in only 2 of the 6 years. Water use efficiency (WUE) increased as N rate increased, irrespective of fertilization frequency. Highest WUE was obtained by 6‐year fertilization treatment and for most treatments WUE decreased .when annual fertilization ceased. Although residual N derived from previous fertilization seems to be very important for subsequent crop production, availability of N from residual sources was not sufficient to maintain maximum crop production over a number of years.
Effect of Phosphorus Nutrition on Response of Perennial Ryegrass Cultivars to Maleic Hydrazide1
Authors: Nittler L. W. , Kenny T. J.
Published: July 2010

Previously perennial ryegrass, Lolium perenne L., cultivars were found to differ in response to soil treated with maleic hydrazide (l,2‐dihydro‐3,6‐pyridazinedione). However, several cultivars were similar in response to the chemical and results varied from one experiment to the next. The investigation reported here was conducted to improve precision and reliability of cultivar purity tests in which maleic hydrazide (MH) is used. Sand‐nutrient culture was used to eleminate soil type as a variable. Every 4th day seedlings were supplied either with a complete nutrient solution or with a solution lacking phosphorus. After the first 12 days, flats on which the solution lacking P was used were supplied with a complete nutrient solution. Starting 18 days after planting, a 300 ppm MH solution was applied to the sand every 4th day. Photoperiods were 8 hours and temperature was 25 C during light periods and 16 C during dark periods. Upper leaf blades started to become chlorotic 12 days after MH treatment was started and cultivars differed markedly. Cultivar differences were greater for plants grown without P the first 12 days than for plants grown with complete solution the entire experiment. The upper leaf blade of most ‘NK‐200’ plants became yellow but the next lower leaf blade remained green. In contrast, both upper and second leaf blades of ‘Manhattan’ plants tended to remain green. Second leaf blades of ‘Pennfine’ plants tended to become chlorotic at about the same rate as upper leaf blades. This procedure resulted in greater contrast between cultivars than was obtained in previous experiments. A series of ten experiments demonstrated that very similar results can be obtained from one experiment to the next.
Effect of Vel 4207 and Dicamba on Bermudagrass and Broadleaf Weeds1
Authors: Johnson B. J.
Published: July 2010

Controlling weeds in turfgrasses without injuring the turf and surrounding plants in turf areas is a major concern. Dicamba (3,6‐dichloro‐o‐anisic acid) has been widely used for broadleaf weed control in turfgrass. Since dicamba leaches through the soil it is likely to cause chemical damage to other than turf plants in the area. These field studies were initiated to determine if Vel 4207 [N‐phenyldiethanolamine bis (2‐methoxy‐3,6‐dichlorobenzoate)] which leaches less in the soil than dicamba would give comparable weed control and without serious injury to turf. The soil types were Cecil sandy loam (Typic Hapludult), Pacolet sandy loam (Typic Hapludult), Gwinnett sandy clay loam (Typic Rhodudult), Durham sandy clay loam (Typic Hapludult) and David sandy clay loam (Rhodic Paleudult) in the weed experiments and Appling sandy clay loam (Typic Hapludult) in the turfgrass tolerance experiment. Dicamba and Vel 4207 at 1.1 and 2.2 kg/ha were applied as single and repeated treatments for comparison of weed control in dormant bermudagrass [Cynodon dactylon (L.) Pers.] and to determine the effects of these chemicals on quality of five actively growing bermudagrass cultivars. There was no difference in control of common chickweed [Stellaria media (L.) Cyrillo] with either Vel 4207 or dicamba. Two applications of Vel 4207 at 1.1 kg/ha were required for satisfactory control of spur weed (Soliva sessilis P.&K.) and henbit (Lamium amplexicaule L.) while similar control was obtained with a single dicamba treatment. One application of dicamba at 2.2 kg/ha controlled a higher percentage of corn speedwell (Veronica arvensis L.) than Vel 4207 applied at the same rate. However, the control was equal when each was applied in two applications at 2.2 kg/ha. Vel 4207 did not control parsley‐piert (Alchemilla microcorpa Boissier Reuter) satisfactorily while two applications of dicamba at 2.2 kg/ha resulted in acceptable control. When Vel 4207 was applied to actively growing bermudagrasses, the turf tolerance varied with cultivars. It was just as safe as dicamba treatments, however, and there was no difference in quality of turf in treated or untreated plots by 7 weeks after treatment. These results suggest that Vel 4207 can possibly be substituted for dicamba for the control of selected winter annuals.
Minimum vs. Conventional Tillage in Commercial Sugarbeet Production1
Authors: Glenn D. M. , Dotzenko A. D.
Published: July 2010

In recent years, minimum tillage practices have been applied to sugarbeet (Beta vulgaris L.) production in northeastern Colorado to reduce soil erosion and fuel demands. The objective of this study was to compare the effectiveness of rotary‐strip, no‐plow minimum tillage to conventional plow‐based tillage on commercial sugarbeet fields under center‐pivot sprinkler irrigation relative to soil nitrate movement, weed control, stand establishment, soil compaction, field operations, yield and quality. Minimum tillage was compared to conventional plow‐based tillage in 16 center‐plot‐irrigated fields in eastern Colorado. A 0.10‐ha study site was located in a representative portion of each field. Soils were aridic Argiustoll members of the fine montmorillinitic mesic family. In the spring and midsummer, stand counts and weed counts were conducted to determine stand establishment and the effects of tillage systems on weed populations. Five‐foot deep soil cores were collected in June, July, and November to monitor nitrate movement in each field. After all field operations were completed prior to harvest, water infiltration, soil compaction, soil aggregate distribution, and aggregate stability studies were conducted to determine any differences due to tillage system. Minimum‐tilled sites had significantly lower proportions of furrow soil aggregates 6.4 mm and less in diam but had a higher percentage of aggregates 12.7 to 38.0 mm in diam. Minimum tillage significantly reduced the percentage and stability of row soil aggregates 0.84 to 6.4 mm in diameter. The stability of row and furrow aggregates decreased with increasing size. Nitrate movement was greater and larger concentrations of nitrate were moved to a depth of 75 cm under minimum tillage. The method of tillage had no effect on row and furrow bulk density, water infiltration rate, weed populations, emergence percentage, final stand, yield, quality, or recoverable sucrose. The results demonstrate that minimum tillage produced a sugarbeet crop of comparable tonnage and quality to that of conventional tillage while significantly reducing the number of field operations by 40%.
Chlorotic Dieback in Flax1
Authors: Moraghan J. T.
Published: July 2010

“Chlorotic dieback” of flax (Linum usitatissimum L.) is characterized by leaf chlorosis, dieback of terminal buds, and development of lateral branches; its occurrence is most frequent under cool soil conditions. The cause of this disease was studied under greenhouse conditions. Flax was grown on a calcareous soil (Calciaquoll) at three soil temperatures (7, 16, and 24 C) in the presence and absence of different levels of FeEDDHA and ZnSO4. The dieback syndrome occurred in the absence of Zn at 16 and especially 7 C but not at 24 C. Zinc accumulation in plant tops for a given fertilizer treatment dcreased progressively as soil temperature was reduced from 24 to 7 C. Zinc deficiency in mature plants was associated with plant Zn levels less than approximately 20 ppm, and its severity was inversely related to soil temperature. FeEDDHA decreased Zn and Mn accumulation in plant tops and, in the absence of added Zn, increased degree of Zn deficiency. FeEDDHA with added Zn eliminated leaf chlorosis and spotting of older leaves and increased Fe concentration in young plants. Dieback of main stems and subsequent branch development from the cotyledonary node, the chief features of “chlorotic dieback”, were found to result from Zn deficiency; however, the leaf chlorosis aspect of the disease was influenced by available soil Fe. Apical dominance in flax was decreased by Zn deficiency; soil temperature indirectly affected this characteristic through its influence on plant Zn accumulation. However, the influence of soil temperature on apical dominance was more complex since lateral branch development even in the presence of added Zn was greatly affected by soil temperature. Phosphorus accumulation in flax was markedly decreased by low soil temperatures.
Fragmentation of Cotton Bract and a Technique for Detecting Bract in Cotton Dust1
Authors: Morey P. R. , Raymer P. L.
Published: July 2010

Bract fragments are thought to be a major component of the respirable dust generated during the processing of cotton (Gossypium sp.) lint in textile mills. Byssinosis is an occupational disease affecting susceptible textile workers exposed to respirable dust. Procedures designed to reduce mill dust require that the dust components be identified. The cotton bract is a candidate component. The objectives of this study were (A) to determine if changes occur in the friability and structure of bract during postanthesis development and (B) to develop a tracer technique suitable for following the micronization of this plant part. Whole bracts were collected from greenhouse‐grown cotton, ‘Tamcot SP21’. Bract friability was determined by placing whole bracts in porcelain jars and abrading these plants with porcelain cylinders for ½‐hour on a roller mill. Whole anthesis bracts were broken apart to the extent that 6% of their weight was collected in a particle size fraction < 250 μm. By contrast, in bracts collected from 20 to 120 days postanthesis there was a trend toward a greater percent of the bract to be broken apart to a particle size of < 250 μm by the same procedure. Observation of tissue sections prepared from bracts showed that this change in friability was associated with an increased number of lignified bundle sheath parenchyma cells and tracheary elements in bract veins. Other anatomical changes accompanying bract senescence included significant decreases in epidermal, mesophyll, and lamina thickness at or shortly after the time of capsule dehiscence. Four fluorescent dyes and two fluorescent brightening agents were applied separately in aqueous solution to cotton bract and leaf trash. Colour Index Basic Yellow 37 was found to be the most suitable dyeing agent. Two‐ to 10‐μm diameter particles obtained from the pulverized remains of dyed bract were distinguished from undyed bract particles of the same size by observation with an epifluorescence microscope using a 334‐ to 365‐nm exciter beam at a magnification of 625 ✕. Significant differences in friability of dyed and undyed bract were not observed by roller mill tests. It is reasonable to conclude that these tracer procedures will identify the bract component in respirable cotton mill dust.
Maintaining Tall Fescue Stands in Association with Bahiagrass1
Authors: Hoveland C. S. , McCormick R. F. , Carden E. L. , Rodriguez‐Kabana R. , Shelton J. T.
Published: July 2010

Bahiagrass (Paspalum notatum Flugge) generally dominates the sward when grown in association with tall fescue (Festuca arundinacea Schreb.) in the lower southeastern U.S. If a management system could be devised to maintain tall fescue in association with bahiagrass, this mixture could provide grazing over a longer season than either of the two grasses when grown alone. The objective of this study was to determine the influence of rates and time of N application and stubble height on persistence and productivity of a tall fescue‐bahiagrass sward. ‘Pensacola’ bahiagrass was overseeded on established ‘Kentucky 31’ tall fescue at two field locations in central (typic hapludult, fine‐loamy siliceous soil) and southern (typic hapludult, coarse‐loamy, siliceous soil) Alabama. Five rates of winter and summer‐applied N were used in combination with summer rest and summer stubble heights of 10 and 4 cm over a 3‐year period to measure seasonal forage production and persistence. Winter application of 224 kg N/ha and summer resting or summer cutting at a 10 cm stubble resulted in best tall fescue persistence. Summer cutting to a 4‐cm stubble reduced tall fescue stands and production, regardless of N rates or time of application. Total forage yields were highest when bahiagrass dominated the sward. Tall fescue persisted better in central than in southern Alabama. Seasonal productivity of a tall fescue‐bahiagrass mixture during the third year was best with a winter N rate of 224 kg/ha N and summer stubble height of 10 cm. Both summer N and close clipping accelerated the shift from tall fescue to bahiagrass. This study emphasized the difficulty of maintaining tall fescue stands in association with bahiagrass. Nematode populations build to high levels in these sandy loam soils and seriously damage tall fescue while bahiagrass is relatively tolerant. Only under high rates of winter N fertilization and a high summer stubble height was it possible to maintain tall fescue in the mixture in central Alabama. Further south, bahiagrass can be expected to dominate the sward in a few years, regardless of management.
Time and Frequency of Irrigation in Relation to Growth Stages of Barley1
Authors: Sepaskhah A. R.
Published: July 2010

Competition of winter and summer annual crops for irrigation water is a vital problem in areas of short water supply. Proper time and frequency of irrigation are essential for the most effective use of water and optimum grain yield of barley (Hordeum vulgare L.). This experiment was conducted in a calciorthids clay loam soil and in a region with 10‐year average rainfall and evaporation of 252 and 1,453 mm, respectively. Complete randomized design was used to compare the effects of no irrigation (I0); one irrigation at either heading (I1), flowering (I2) or dough stage (I3); two irrigations at either heading and flowering (I12), heading and dough stage (I13) or flowering and dough stage (I23); and three irrigations at the heading, flowering, and dough stage (I123) on the grain yield, yield components and water use efficiency of Zarjo barley for 2 years. One irrigation at the flowering stage resulted in an average grain yield increase of 35% compared with no irrigation treatment and was found to be preferable to irrigations at any other stages of growth with respect to both grain yield production and water use efficiency. The lower grain yields at the no irrigation and the one irrigation at dough stage treatments were resulted mainly from the lower weight of 1,000‐seed. Flag leaf xylem water potential lower than −25.8 bars possibly reduced the translation of assimilates into the grain and caused the lower weight of 1,000‐seed. The straw yield was not affected by the irrigation treatments since they were imposed after completion of vegetative growth. One irrigation a the flowering period may be suggested for obtaining both higher water use efficiency and grain yield of barley as winter‐annual crop under irrigation in the southern region of Iran.
Effect of Peanut Hulls on the Performance of Corn1
Authors: Lutz J. A. , Jones G. D.
Published: July 2010

Disposal of peanut (Arachis hypogaea L.) hulls, after separation from the seed, is a serious problem in the peanut production areas of southeastern Virginia. Limited amounts of peanut hulls are used for mulch around shrubbery, but commercial use is limited, resulting in a large volume being burned, thus contributing to the pollution hazard. Became of their chemical composition and potential use as a mulching material, it is thought that they may be of considerable importance in corn (Zea mays L.) production. The objective of this investigation was to evaluate the effect of peanut hulls on the growth, yield, and chemical composition of corn, and on soil moisture. The experiment was conducted for 2 consecutive years on Tatum (Typic Hapludults, clayey, mixed, thermic) silt loam at Orange, Virginia. Hulls were applied at rates of 0, 21, 42, and 84 metric tons/ha on unfertilized plots and on plots that received 112 kg N/ha, 49 kg P/ha, and 93 kg K/ha. Hulls increased the growth and yield of corn by increasing the available moisture content in the 0‐ to 15‐cm soil depth. Hulls also increased the K concentrations of corn silage from 0.99 to 1.77% on unfertilized plots and from 1.32 to 2.04% on fertilized plots. The Mg concentration was decreased from 0.43 to 0.25% on unfertilized plots and from 0.35 to 0.29% on fertilized plots. The N, P, and Ca concentrations of corn silage were not significantly affected by peanut hull applications. Hulls did not increase the number of nematodes in the soil. Results of this experiment indicate that peanut hulls can be used effectively in corn production.
Effect of Nitrapyrin on Nitrification of Fall and Spring‐Applied Anhydrous Ammonia1
Authors: Touchton J. T. , Hoeft R. G. , Welch L. F.
Published: July 2010

Nitrification of ammonium fertilizers in late fall and early spring and subsequent nitrate losses through leaching and denitrification are a continuing economical and environmental concern. To evaluate the effects of nitrapyrin on nitrification, anhydrous ammonia with and without nitrapyrin was applied in the fall and spring to poorly drained soils in southern, central, and northern Illinois. Nitrogen and nitrapyrin rates ranged from 0 to 268 and 0 to 1.12 kg/ha, respectively. Detailed sampling from ammonia retention zones was conducted throughout the fall, spring, and summer. Effects of nitrapyrin on nitrification varied with time of application, nitrapyrin rate, and soil type. In central Illinois, nitrification of fall‐applied N, with or without nitrapyrin, was relatively rapid in a silty clay loam soil until the soil temperature dropped below 10 C, but less nitrification occurred when nitrapyrin was applied. On similar soil in the northern part of the state, when the soil temperature was below 10 C at application, nitrapyrin was more effective in controlling nitrification. Time required for amonium‐N in soil to drop to levels equal to that in the control (no N or no nitrapyrin) increased with N and nitrapyrin rates except with spring‐applied N in central Illinois in 1975 where increasing nitrapyrin rates above 0.28 kg/ha had no additional effect on inhibition of nitrification rates. Nitrapyrin applied to a silt loam soil in southern Illinois in the spring or fall of 1975 had no significant effect on nitrification, but nitrapyrin used with spring‐applied N in 1976 was effective in controlling nitrification through early June.