bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Clipping Height, Clipping Frequency, and Rates of Nitrogen on Yield and Energy Content of Coastal Bermudagrass
Authors: Ethredge Jerome , Beaty E. R. , Lawrence Roger M.
Published: July 2010

In recent years the acreage in ‘Coastal’ bermudagrass (Cynodon dactyton (L) Pers.) has increased rather sharply in the southeastern United States. Traditionally, Coastal is grazed and fertilized with moderate levels (less than 100 kg/ha) of N. Usually forage yield data have been collected by mowing, which leaves a stubble of 6 cm or more high. Significant quantities of forage are not harvested. A serious question has arisen as to the validity of much of the research data when applied to utilization of Coastal by grazing.

To secure research data that would relate Coastal production more effectively to grazing situations, an investigation was conducted over a 2‐year period as to the effects of intense, moderate, and lax defoliation on forage yields of Coastal bermudagrass. Forage yields were highest with the shortest clipping height, 0 cm, and lowest with the highest clipping height, 14 cm. Clipping height and N rate influenced production significantly, but clipping frequency had little effect on total yield. Tiller production indicated that all treatments maintained vegetative cover on the area.

Early in the season large quantities of forage were available below 7 cm. Up to 1800 kg/ha of forage were available between 0 and 7 cm.

Height of clipping did not appear to be important in the survival of Coastal bermudagrass and in the production of the maximum amount of usable energy. A low clipping height combined with a relatively short clipping frequency appear to be best.
Selenium Content of Field Crops Grown on Selenite‐Treated Soils1
Authors: Cary E. E. , Allaway W. H.
Published: July 2010

Experiments were conducted to determine the potential for using soil application of Se to prevent Se deficiency in livestock and to determine how long a single application of Se might be effective. Sodium selenite was added to soil at rates of 2.24 and 4.48 kg/ha of Se in five different fields. The fields were cropped to corn (Zea mays L.), oats (Avena sativa L.), and/or various forage crops for 4 years following application. Selenium concentrations in the crops over the 4 years were usually maintained at levels (>0.1 ppm Se) that would have protected animals that consumed these crops from Se‐deficiency diseases. The highest Se concentrations were below generally accepted limits for acute Se toxicity. Plant analysis appears to be more useful than soil analysis for monitoring this practice.
Effect of H2SO4 in High Sodium Irrigation Water on the Growth of Peas and Beans in Calcareous Soil1
Authors: Ryan J. , Miyamoto S. , Bohn H. L.
Published: July 2010

Preliminary experiments were conducted to evaluate the addition of H2SO4 to high Na water for the purpose of preventing or reducing plant uptake of Na by increasing the solubility of Ca. The addition of up to 4 meq/liter of H2SO4 to irrigation water containing 1 to 40 meq/liter of NaCl had no significant effect on the growth of peas (Pisum sativa) and beans (Phaseolus vulgaris) cropped twice in calcareous soils in greenhouse experiments. However, H2SO4 had an adverse effect at NaCl concentrations of 60 and 80 meq/liter. Sodium concentrations greater than 10 meq/liter appeared to decrease the yield of both plants. A leaching fraction of 0.3 ± 0.05 was maintained. The Na content of the plant material increased as the Na content of the irrigation water increased, but no reduction in Na content was observed with the H2SO4 treatment. The Ca content was not affected. The results suggest that this practice was ineffective at the H2SO4 concentration range studied.
Comparison of Fog Irrigation with Surface Irrigation in Corn Production1
Authors: Doss B. D.
Published: July 2010

Water stress by plants during silking and ear development often affects the yield of corn (Zea mays L.). Water stress sometimes occurs during midday even with a relatively high soil water content. Field experiments were conducted for 3 years to determine the effect of fogging or mist irrigation alone, surface irrigation alone, and fogging plus surface irrigation on plant characteristics and grain and stover yields of corn. Plants received mist irrigation daily from 1000 until 1600 during silking and ear development. Surface irrigation was applied to maintain soil water at or above the 50% available level (0.8 bar) in the surface 60 cm of soil.

An increase in grain yield was obtained in each of the 3 years with surface irrigation and in 2 of the 3 years with fogging or mist irrigation, but fogging in addition to surface irrigation did not increase grain yields above those for surface irrigation alone. Average grain yields for the 3 years were 6,200, 8,400, 9,200, and 9,500 kg/ha for no irrigation, fogging, surface, and fogging plus surface irrigation, respectively. Surface irrigation appears to be a much more efficient method of water application than fog irrigation since the amount applied as fog was almost twice the amount applied as surface irrigation.
Measurement of Foliage Height and its Relationship to Yields of Two Tropical Forage Grasses1
Authors: Whitney A. S.
Published: July 2010

Direct visual estimates of average foliage height based on a 28 ✕ 28 cm sampling area could be made at a rate of 7.5 readings/minute using a new device which utilized a plastic fresnel lens.

Foliage height was estimated (5 readings/plot) for kikuyugrass (Pennisetum clandestinum Hochst. ex. Chiov.) and pangola digitgrass (Digitaria decumbens Stent) swards which varied widely in yield due to different nitrogen and gibberellic acid treatments. Average foliage height explained 94% of the variation in dry matter yields in both cases, but the regression slope was different for the two grasses. Sampling error was low in relation to experimental error. The calculated number of samples required to estimate the mean foliage height was 8 to 9 samples/plot for estimates ±2 cm and 4/plot for ±3 cm (P = 0.95).

This approach appears especially promising for estimating forage growth rates where nondestructive sampling is desired and where swards are variable, i.e. as in grazed paddocks.
Selective Smutgrass Control and Forage Quality Response in Bermudagrass‐Dallisgrass Pastures1
Authors: Smith James E. , Cole A. W. , Watson V. H.
Published: July 2010

Smutgrass (Sporobolus poiretii Roem and Schult.), a prevalent and increasingly serious weed problem in pasture areas of the southeastern United States, cannot be selectively controlled in swards containing desirable forage species with the available recommended procedures. Dallisgrass (Paspalum dilatatum Poir.)‐bermudagrass (Cynodon dactylon (L.) Pers.) pasture swards, the most prevalent type of pastures in our region, were selected for uniform infestation of smutgrass and treated with atrazine [2‐chloro‐4‐(ethylamino)‐6‐isopropylamino)‐s‐triazine] at 4.48 and 8.96 kg/ha; bromacil (5‐bromo‐3‐sec‐butyl‐6‐methyluracil) at 2.24 and 4.48 kg/ha; and MSMA (monosodium methanearsonate) at 2.24, 4.48, and 8.96 kg/ha in the fall of 1970 and 1971. From 83 to 97% smutgrass control was obtained with a single application of atrazine or bromacil with no more than 38% injury to bermudagrass and 28% injury to dallisgrass. Maximum smutgrass control obtained with MSMA application was 63% which also resulted in 89% dallisgrass control. Forage quality determinations in the spring following smutgrass control indicated that total forage was more acceptable when smutgrass was controlled.
Estimation of Organic Matter in Atlantic Coastal Plain Soils With a Color‐Difference Meter1
Authors: Page Norwood R.
Published: July 2010

Reflectance (L on L,aL,bL scale), determined with a color‐difference meter, was compared to the WalkleyBlack method as a measure of organic matter concentration in the surface horizons of 96 Coastal Plain soils. Reflectance values were highly correlated (r = 0.89) with soil organic matter (determined by the Walkley‐Black method) within the O to 5% range. On these soils, organic matter can be predicted from reflectance by the equation = 16.03 − 0.53X 4. 0.01X2. The procedure is faster and more economical than other methods for estimating soil organic matter.
Soil pH, Excess Lime, and Chelating Agent on Micronutrients in Soybeans and Bush Beans1
Authors: Wallace A. , Mueller R. T. , Cha J. W. , Alexander G. V.
Published: July 2010

‘Hawkeye’ (Fe‐chlorosis resistant) and ‘PI54619‐5‐I’ (Fechlorosis sensitive) soybeans (Glycine max L.) were grown with and without DTPA (diethylene triamine pentaacetate) in Yolo loam soil which had been amended (S or CaCO3) to give different soil pH values and to simulate high carbonate conditions in soil. The purpose was to study heavy metal relationships with the soil amendments including a synthetic chelating agent. Sulfur decreased yields, but CaCO3 did not. Sulfur consistently increased leaf concentrations of Mn, Zn, Cu, Co, and Ni, but decreased leaf concentration of Mo. Manganese toxicity was evident when soil had been acidified with S. CaCO3 (pH 7.5) increased leaf concentrations of Cu, Ni, and Mo. PI54619‐5‐1 soybeans tended to contain lower levels of metals than did Hawkeye. DTPA, particularly at 50 ppm in soil, increased leaf concentrations of Fe, Mn, Zn, Cu, Co, Ni, and Mo. It increased Ti in leaves for the PI54619‐5‐1 soybeans only. DTPA increased the concentration ratio of leaves to stems for Fe, Zn, Cu, Co, Ni, and Mo. The effect was most pronounced for Ni. However, S increased the micronutrient concentrations in both leaves and stems. In bush beans (Phaseolus vulgaris L. var. ‘Improved tendergreen’) DTPA at soil pH 6 increased the leaf‐stem ratio of Fe, Zn, Cu, and Ni, but to a lesser extent than in soybeans.
Sulfuric Acid Applications to Calcareous Soils: Effects on Growth and Chlorophyll Content of Common Bermudagrass in the Greenhouse1
Authors: Ryan J. , Stroehlein J. L. , Miyamoto S.
Published: July 2010

Iron deficiency is often a serious problem in common bermudagrass (Cynodon dactylon L.) grown on calcareous soils. This study was carried out in order to determine the effects of applications of sulfuric acid, an abundant material from the copper industry, on bermudagrass grown on calcareous iron‐deficient soils. Cave (Typic Paleorthid) and Stewart (Typic Nadurargid) soils were placed in pots and sulfuric acid was applied 1) to the soil surface, 2) mixed with the soil, 3) as a band, or 4) localized as spots prior to seeding. Ferrous sulfate, iron chelate (Fe‐EDDHA), and an iron‐bearing copper refining byproduct, “jarosite”, were included for comparison. The 93% H2O4 was the most effective material in increasing growth of the plant material by alleviating iron deficiency, the effect decreasing for the first four of seven harvests over a 1‐year period. There was no difference between H2SO4 application methods at equivalent rates. Surface‐applied H2SO4 increased chlorophyll concentrations in the plant with increasing rates but was not as effective as either FeSO4 7H2O or Fe‐EDDHA. Application of 3% H2SO4 in the irrigation water was as effective as these materials in alleviating chlorosis on a series of previously untreated pots. Results indicate that H2SO4 may be useful for treating iron‐deficient bermudagrass, a common turf and seed crop in the Southwest.
Subsoil Chiseling and Slip Plowing Effects on Soil Properties and Wheat Grown on a Stratified Fine Sandy Soil1
Authors: Kaddah M. T.
Published: July 2010

Positive crop growth response to deep tillage in sandy soils has been observed in Imperial Valley, California. Very little information is available, however, on the effect of different deep tillage operations and the possible causes of the beneficial effects of deep tillage. The present field study was conducted on a stratified fine sandy soil to evaluate the effect of subsoil chiseling and slip plowing to a depth of 90 cm on wheat (Triticum aestivum L.) yield and soil properties. Conventional soil disking to 20 cm depth was compared with two subsoil chiseling and two slip plowing treatments. Subsoil chiseling was on 1‐m centers in one and in two directions, and slip plowing was on 2‐m centers in one or two directions. The two directions of deep tillage were at right angles to each other.

Significant increases in wheat yield resulted from deep tillage. Grain yield (metric tons/ha) were: 4.50 for disking; 5.15 for subsoil chiseling in two directions; 5.73 for slip plowing one direction; and 6.32 for slip plowing in two directions.

Along the silts formed by the subsoil and slip plow as compared with areas between slits or areas disked only: (a) stratified sandy soil layers were more disturbed, (b) root and shoot growth and water intake rate were significantly increased, (c) soil strength was significantly decreased, and (d) bulk density decreased in some layers but not in others.

Following subsoil chiseling and slip plowing of the fine sandy soils in Imperial Valley, reduction in soil strength apparently enhanced root penetration in the soil. More information is needed to clarify the effects of other factors such as bulk density changes, water movement and nutrient distribution in the soil profile.
Propionic Acid as a Hay Preservative1
Authors: Knapp W. R. , Holt D. A. , Lechtenberg V. L.
Published: July 2010

In search of a method to prevent quality deterioration in hay stored before it is adequately cured, propionic acid was added to hay at baling time. Its effectiveness as a preservative was evaluated. Alfalfa (Medicago sativa L.) hay was baled at 32.4% moisture. Immediately after baling, propionic acid was applied to the bales at rates of 0.02, 0.2, 0.5, and 1.0% of the weight of the hay. The hay was then covered with polyethylene for 48 hours. Temperatures were recorded for 3 weeks following treatment. Samples were taken at baling and after 2 months in storage.

All of the untreated hay became moldy, heated to ≥ 55 C, and showed significant losses in dry matter, carbohydrates, in vitro dry matter disappearance, and in vitro cell wall disappearance during storage. Total N, ammonium N, and acid detergent fiber N concentrations increased in control and treated hay during storage.

Hay treated with < 1% propionic acid underwent storage changes similar to those occurring in untreated hay and was not effectively preserved. The 1% acid rate inhibited molding and heating and reduced dry matter loss during storage from 15.1 to 7.6%. Decrease in in vitro dry matter and cell wall disappearance during storage was least with 1% acid treatment. Acid treatment reduced loss of in vitro cell wall disappearance. These results indicate that propionic acid may have value for preserving incompletely cured hay if it is applied at rates of ≥ 1%.
Chloride Accumulation Near Corn Roots Under Different Transpiration, Soil Moisture, and Soil Salinity Regimes
Authors: Sinha B. K. , Singh N. T.
Published: July 2010

The magnitude of 36Cl accumulation around roots of corn (Zea mays L.) plants exposed to low, medium, and high transpiration rates was studied in laboratory experiments using Tulewal loamy sand (a Typic Ustochrept) salinized to ECe of 3 and 6 m mhos/cm with sodium chloride. Radioautographs and quantitative measurements of 36Cl in high transpiration treatment showed the highest concentration of the element in regions closest to the root. At high transpiration rates the chloride content of the soil close to the roots increased while the same soil showed a decrease in the chloride content when the plants were exposed to low transpiration treatment. Chloride concentrations in the ‘apparent free space’ and soil close to the roots was two to three times that in the bulk soil, depending upon the amount of water transpired/unit root length. At higher transpiration rates, salt accumulation increased with greater soil moisture content but was either unaffected or decreased closer to the rootsoil interface, when the transpiration rate was low. The results indicate that the salinity tolerance limits of plants would be greatly influenced by the prevailing evaporative demand.
Susceptibility of Alfalfa Cultivars to Triazine Herbicides1
Authors: Harvey R. G. , Rohweder D. A. , Fawcett R. S.
Published: July 2010

While simazine [2‐chloro‐4,5‐bis(ethylamine)‐s‐triazine] has been used for several years to control perennial broadleaf weeds in alfalfa (Medicago sativa L.), it occasionally fails to provide adequate weed control, or causes crop injury. Other triazine herbicides have been shown to provide more reliable weed control but also may injure the crop. Consequently, this study was conducted to determine which triazine herbicide was least injurious to alfalfa and if alfalfa cultivars differed in their susceptibilities to the herbicides. Included in the study were five alfalfa cultivars and the herbicides atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine], cyanazine [2‐chloro‐4‐ (1‐cyano‐1‐methylethylamino)‐6‐ethylamino‐s‐triazine], secbumeton (2‐sec‐butylamino‐4‐ethylamino‐6‐methxy‐s‐triazine) and simazine.

The cultivars were established on silt loam (Typic Argin‐doll Fine‐Silty Mixed Mesic) and loamy sand (Typic Udipsament Sandy‐Mixed) soils. Results of tests conducted on both soils indicated that the ‘Vernal,’ ‘Saranac,’ and ‘Iroquois’ cultivars had the greatest yield potential under Wisconsin conditions, but when expressed as a percentage of yield in untreated plots, the ‘Tempo’ cultivar was injured least by the herbicides. The ‘DuPuits’ cultivar, while initially responding to the triazine herbicides much like the other cultivars, exhibited greater injury after overwintering. Initial injury to the Vernal cultivar on the silt loam soil was greatest from atrazine, secbumeton, and cyanazine, but recovery was nearly complete by the spring following treatment. On the loamy sand soil, however, atrazine and high rates of simazine produced the greatest initial injury, and injury to the Vernal cultivar persisted through the following spring.
In vivo Performance of Bloom and Bloomless Sorghum Forage1
Authors: Cummins D. G. , Sudweeks E. M.
Published: July 2010

In vitro digestibilities of green leaf segments of bloomless sorghum [Sorghum bicolor, (L.) Moench] are higher than those from bloom (white, powdery‐appearing wax on leaf and stem surfaces) sorghum, but it is not known if these differences will affect performance of animals fed bloom and bloomless sorghum forages. The objective of this study was to determine through in vivo trials if the bloomless characteristic of sorghum forage affected digestibility and animal performance. Two near isogenic lines of ‘Redbine 60’ sorghum differing primarily in the bloom and bloomless characterstic were grown under uniform conditions for 3 years at Experiment, Ga. At the dough stage of grain maturity, forage was harvested and ensiled in 1973 and 1974 and stored briefly at —13 C in 1975. Rumen volatile fatty acid production in steers fed silage was higher from the bloomless sorghum than the bloom sorghum, which indicates greater digestion of the bloomless sorghum. Steers fed bloom and bloomless sorghum silage did not differ in average daily gains at the end of a 6‐week period, but the latter gains were significantly higher at the end of the second week. Green forage digestibility by sheep was higher on the bloomless compared to the bloom type for dry matter, crude protein, crude fat, and crude fiber. These studies suggest that quality of sorghum forage may be improved by developing hybrids with the bloomless characteristic.
Application of Statistical Design Theory to Crop Estimation with Special Reference to Legumes and Mixtures of Cultivars1
Authors: Federer W. T. , Hedayat A. , Lowe C. C. , Raghavarao D.
Published: July 2010

Forage crop researchers often need to determine the proportion of legume, weed, and grass contents of hay. This is often done by sampling and hand‐separation or by visual estimates of the relative proportions. The sampling and hand‐separation method is costly and time‐consuming, and both procedures are subject to errors of separation and vagaries of sampling. As alternatives, procedures employing mixtures of cultivars and spring balance weighing design and balanced, incomplete block design theory are presented. Errors and biases associated with sampling and hand‐separation and visual‐estimate procedures are eliminated. Also, a procedure is presented to measure the general competitive effects of cultivars and to determine how much more (or less) effective a cultivar is in a blend than when grown alone.
Soybean Nodulation as Affected by Wheel Traffic1
Authors: Voorhees W. B. , Carlson V. A. , Senst C. G.
Published: July 2010

A significant quantity of nitrogen is made potentially available for plant uptake through symbiotic fixation in the nodules of legume roots. Several aspects of soil environment that can affect the formation and development of these nodules can be altered by soil being compacted by farm vehicular wheel traffic. Field experiments were conducted on a Nicollet silty clay loam (Aquic Hapludoll) to define the extent to which wheel traffic can affect nodulation on roots of soybeans [Glycine max (L.) Merr. ‘Corsoy’]. Wheel traffic of tractors and implements during normal field operations for soybean culture in the northern Corn Belt was controlled to produce soybean rows with no wheel traffic on either side, and wheel traffic on only one or both sides. Measurements of nodule number and mass from undisturbed soil monoliths showed that rows with wheel traffic on both sides had from 20 to 30% fewer nodules and about 36% less total nodule mass than rows with wheel traffic on only one side. Wheel traffic increased the specific nodule mass in both the tracked interrow area and the adjacent nontracked row area. Nontracked interrows had a greater percentage of nodule mass in the upper 30 cm than did wheel tracked interrows. Thus, by controlling the wheel traffic of normal farming operations, the quantity and distribution of nodules can be altered in ways which have implications for increasing nitrogen fixation.
Colorimetric Determinations of Exchangeable Ammonium, Urea, Nitrate, and Nitrite in a Single Soil Extract1,2
Authors: Onken Arthur , Sunderman Herbert D.
Published: July 2010

Interest in N transformations in soils has increased greatly in recent years, particularly with increased use of urea‐containing fertilizers. However, only one procedure for determination of exchangeable ammonium, nitrate, nitrite, and urea in a single soil extract has been proposed and it requires the use of both distillation and colorimetric equipment. It would be useful to have a set of colorimetric procedures for the determination of these N forms in a single extract. Previous research indicated sodium sulfate, as an extractant, would be least likely to produce unwanted interferences in these procedures. Thus, research was initiated to determine (i) if Na2SO4, could be used as an extractant for exchangeable NH4+, NO3‐, NO2‐ and urea and (ii) necessary modifications to make desirable colorimetric procedures usable in a Na2SO4 extraction system.

A procedure for the colorimetric determinations of exchangeable NH4+, urea, NO3‐, and NO2‐ in soil using a single soil extract is described. The soil sample is extracted with Na2SO4 containing phenylmercuric acetate for 30 min and then leached with four 25 ml portions of extractant and made to volume. The extract is analyzed for NH4+ by a modified Nessler reagent, urea by either diacetyl monoxime and thiosemicarbazide or p‐dimethyl aminobenzaldehyde depending on concentration, NO3‐ by chromotropic acid and NO2‐ by 4‐aminobenzenesulfonic acid and 1‐aminonaphthalene hydrochloride. The procedure gave quantitative recovery of NH4+‐N, urea‐N, NO3‐ N, and NO2‐‐N added simultaneously to five different soils.
Fitting Plants Nutritionally to Soils. II. Cotton1
Authors: Brown J. C. , Jones W. E.
Published: July 2010

Fifteen cotton varieties (Gossypium hirsutum L.), representing germplasm recommended for different areas of the United States, were subjected to Fe, Zn, and Cu stresses and Al and Mn toxicities to determine their nutrient requirements. They were grown on the seven different soils described in part I of this study for soybeans. All cotton varieties grown on Quinlan soil (Fe stress) developed deficiency symptoms that were similar to symptoms produced in cotton grown on Shano and Taunton soils (Zn stress). On Quinlan and Taunton soils, the plants responded to both Fe and Zn. Iron added to Taunton soil decreased the uptake of Fe and increased the uptake of Zn by the plants. Lime added to Richland soil induced a Zn deficiency that increased Fe uptake by the plants. When Zn was added to this soil, yields increased and Fe uptake decreased in the plants. All 15 cotton varieties grew poorly on acid Bladen soil (Al toxic), and yields were doubled by liming and yield of C‐7105, 73‐319 doubled again by adding Cu. Best yields, with no toxicity symptoms, were obtained on Richland soil (Mn toxic). Cotton and soybean had different nutrient requirements. For example, cotton was Cu and Zn inefficient and Mn tolerant, whereas soybeans were Cu and Zn efficient and Mn intolerant in most varieties tested.
Use of a Weighted‐disk Measure as an Aid in Sampling the Herbage Yield on Tall Fescue Pastures Grazed by Cattle1
Authors: Vartha E. W. , Matches A. G.
Published: July 2010

Measurement of herbage‐on‐offer in grazing trials is useful for monitoring seasonal changes in herbage availability, for defining the grazing pressure, and may serve as the basis for adjusting rates of stocking. Generally, a large number of samples must be harvested per pasture in order to obtain reliable estimates of herbage yield. However, the amount of labor and time needed to harvest and process samples may limit the number of samples which may feasibly be taken per pasture. In this experiment, our objective was to maintain precision with a low number of harvested samples by first determining the mean bulk‐height of the pasture with a weighted disk measure and then harvesting sites of the mean bulk‐height (± 1/2 cm). Every 5 days, 25 measurements of bulk‐height were made at random locations per paddock with a weighted disk meter having a 0.2 m2 disk weighing 2.5 kg and dropped from a height of 80 cm. Mean bulk‐height was calculated and 10 quadrats (0.25 m2) harvested per paddock from locations having the mean bulk‐height. The data obtained in pastures of tall fescue (Festuca arundinacea Schreb.) were influenced by period of sampling (spring, summer, and fall) and grazing treatments (1‐, 2‐, or 4‐paddock rotation). The coefficients of variation for fresh herbage yield of 10 0.25 m2 quadrats at the mean bulk‐height within grazing treatments, were about 5%. For combined data from the grazing treatments, correlation coefficients (r) between herbage mean bulk‐height and dry herbage yield as determined from the harvested quadrats were 0.714, 0.822, and 0.709 for spring, summer, and fall growth. However, the correlation coefficients varied both in spring and fall according to different grazing treatments. In spring grazing, r's were 0.399, 0.918, and 0.670; and in the fall grazing, r's were 0.300, 0.848, and 0.580 for the 1‐, 2‐, and 4‐paddock systems, respectively. Correlation coefficients varied less in summer with r's of 0.904, 0.914, and 0.772 for the 1‐, 2‐, and 4‐paddock systems. Trampling of forage and accumulation of mature residue in some grazing treatments appeared responsible for the low correlation between mean bulk‐height and harvested herbage yield. Use of the disk‐meter appears to have greatest usefulness in pastures where there is not excessive accumulation of plant residues due to undergrazing or trampling. Under such conditions, sites located by mean bulk‐height allow the experiments to quickly obtain reliable herbage yield estimates from fewer sampling sites.
Cotton Seedling Metabolism as Influenced by Germination Temperature, Cultivar, and Seed Physical Properties1
Authors: Krieg D. R. , Carroll J. D.
Published: July 2010

Growth rates of cotton (Gossypium hirsutum L.) seedlings are greatly reduced at minimal germination temperatures. Increased variability in the seedling growth rates are more apparent at low temperatures, and delayed emergence or seedling death result in more erratic and nonuniform stands. The pupose of this study was to determine if a specific area of metabolism might be controlling seedling growth at less than optimum germination temperatures. Cottonseed of four cultivars were separated into density and weight groups and germinated in the dark under two controlled temperature regimes (20 to 30 C and 15 to 25 C). Seedlings were harvested 3, 6, 9, and 12 days after planting and separated into cotyledons and seedling axes. Chemical analyses of each part were used to describe the utilization of cotyledonary reserves as related to seedling growth rates. At minimal temperatures, radicle growth rates were initially related to lipid use but by 6 days became more closely associated with non‐lipid use. Specific cultivar differences existed with respect to seedling growth and non‐lipid use, with N utilization being most affected. Mineral nutrient transfer varied according to cultivar and temperature with no apparent correlation with seedling growth. The results indicate that at optimum temperatures, seed maturity (density) and quantity of available substrate (weight) determine seedling growth rates irrespective of cultivar. Minimal temperatures resulted in a general decrease in metabolic activity. Genetic differences as to the extent of the reduction were quite apparent, however, and thus controlled seedling metabolism and growth rates. Seedling growth reductions due to temperature were related to problems associated with non‐lipid metabolism, especially the protein fraction. The specific cause of this metabolic abnormality was not identified.
Competitive Effects of Turfgrass on the Growth of Ornamental Shrubs1
Authors: Nielsen A. P. , Wakefield R. C.
Published: July 2010

Planting of a shrub or tree into a mature grass sod may result in poor establishment of the woody species. This experiment was designed to measure the field response of four species of ornamental shrubs to turfgrass competition. The shrubs used were forsythia (Forsythia intermedia zabel), azalea (Rhododendron X), Japanese barberry (Berberis thunbergi DC.) and taxus (Taxus media Rehd.). Turfgrass treatments included plots maintained at high or low rates of N fertilizer and receiving, in some cases, supplemental irrigation to maintain high soil moisture. Treatments with no turfgrass were either bark mulch or bare ground. Turfgrass plots were mowed regularly to a height of 7.6 cm. The effects of these variables were measured by evaluating several aspects of growth and development of each shrub species.

Turfgrass established 2 years previously on an Enfield silt loam (Typic Distrochrepts) significantly suppressed the growth and development of all four species of shrubs as compared to plots where turfgrass was not a competitor. Differences in soil moisture or temperature are not believed to have been responsible for the differences observed in these findings. Plant competition for N was suggested by both the color ratings and analyses of leaf tissue of the shrubs during the first year of shrub establishment. Additional fertilizer, applied as a topdressing, was more beneficial to the turfgrass than to the shrubs, and did not significantly increase their growth in most cases. The addition of K and P did not increase growth in any of the treatments and apparently was not a factor in the competition between the grass and the shrubs.
Relative Evaluation of Water Stress Indicators for Soybeans1
Authors: Sivakumar M. V. K. , Shaw R. H.
Published: July 2010

The understanding of the relationships between changes in crop foliage to variations in the amount and status of soil water is at best incomplete. Since plant growth is directly affected by deficits of water in plants, and only indirectly by soil‐water deficits and atmospheric stresses, the importance of using plant measurements, rather than soil indices, is warranted and has led to this investigation. Field studies were conducted during 1976 on Ida silt loam [fine, silty, mixed (calcareous) mesic family of Typic Udorthents] at the Western Iowa Experimental Farm, Castana, Iowa, to evaluate three plant measurements (vis., stomatal conductance, leaf‐water potential, and leaf area) as water stress indicators for soybeans [Glycine max (L.) Merr.]. Stomatal conductance and leaf water potential were measured at 2‐hour intervals from 0600 to 2000. Stomatal resistance was measured with a diffusion porometer, with stomatal conductance taken as the reciprocal of leaf resistance. Leaf‐water potential was measured using a pressure chamber. Leaf area was measured with an electronic leaf‐area integrator.

Daily means of stomatal conductance and leaf‐water potential measured several times during the growing season were closely related to changes in soil‐water potential. “Rate of leaf‐area expansion” which is defined as the change in average leaf area (leaf area/number of leaves) per plant over a period of time, also showed a close correspondence with soil‐water potential.

Relative growth rates of soybeans showed a negative correlation with stomatal conductance, leaf‐water potential, and rate of leaf.area expansion. The three plant measurements should prove useful in explaining water‐deficit effects quantitatively under field conditions.
Root‐Sink Descriptions of Water Supply to Dryland Wheat1
Authors: Rickman R. W. , Allmaras R. R. , Ramig R. E.
Published: July 2010

Soil water content changes were supplemented with calculations of water flow between soil layers to provide an improved description of water uptake by dryland wheat (Triticum aestivum L.). This root‐sink description of water use, recognizing both measured change in water content and vertical redistribution (upward or downward) of water by flow between soil layers, is needed for a better understanding of plant‐soil and atmospheric factors involved in water stress when the wheat plant must rely on stored soil water for long periods. Water content changes were estimated from neutron meter measurements. Soil water flux was estimated from field measurements of both hydraulic conductivity and hydraulic head gradients; unsaturated conductivity beyond the range of field measurement was calculated with the pore interaction model of Marshall matched to field measured values at 250 mb. Seasonal water‐uptake patterns, determined by the root‐sink description, differed from those shown by only water content measurements. Peak water‐use rates did not coincide with maximum leaf area index, but coincided with the period from heading to completed head extension. Water flux in the profile was important for supplying water during grain filling and was critical in this layered soil, which restricted rooting to depths less than 150 cm.
Production, Digestibility, and Perloline Content of Fescue Stockpiled and Harvested at Different Seasons1
Authors: Fribourg Henry A. , Loveland Richard W.
Published: July 2010

The management of tall fescue (Festuca arundinacea Schreb.) to utilize spring, summer, or early fall production in summer, fall, or early winter, could help harmonize livestock pasture requirements with available forage supply. Such utilization must be accomplished without appreciable loss of quality. The effects of several stockpiling schemes (spring, summer, late summer, fall, and spring + fall) on tall fescue dry matter yield, in vitro digestible dry matter (IVDDM), and perloline and total N contents were investigated over a 3‐year period. Nitrogen at the rate of 50 kg/ha was applied in March and September each year. Yield or composition of stockpiled material was not different when fescue was removed gradually or as a single hay cut, and the year × treatment interaction was not significant. Stockpiling did not affect production at other times of the year. Stockpiling made 3,700, 1,300, 650 and 1,000 kg/ha more dry matter available than continuous clipping in summer, early fall, late fall, and winter from spring, early summer, late summer, and fall stockpiling, respectively. Total N content of stockpiled herbage sometimes was lower than the National Research Council's requirement for a lactating beef cow and, occasionally, for a dry beef cow. Herbage stockpiled in spring, in early summer, and in late summer, had 45, 49, and 59% IVDDM, respectively. Fall‐stockpiled herbage had IVDDM in excess of 60%. The perloline content of stockpiled fescue was low (<0.16 mg/g), but summer regrowth after stockpiling removal had a relatively large alkaloid content (0.46 mg/g). Although the largest yields of stockpiled forage resulted from spring accumulations, the quality was low. Lowest quality was measured in forage accumulated in summer. Stockpiling in late summer or early fall produced sufficient material to extend the grazing season several weeks into winter.
Comparison of Soil Properties under Continuous Corn Grain and Silage Cropping Systems1
Authors: Barnhart Steven L. , Shrader W. D. , Webb J. R.
Published: July 2010

Continuous corn (Zea mays) harvested for grain only, has been subjected to much study. There is little information available, however, as to the effect on such properties as soil pH, organic matter, available P, and exchangeable K when the entire plant is harvested. We compared these soil properties on plots of continuous corn grain and corn silage as part of a rotation‐fertility experiment established in 1957 on a Typic Hapludol soil. Subplot treatments were four levels of applied N—O, 45, 90, and 135 kg/ha. We applied 17 kg/ha of P each year to all plots during the first 4 years of the study and 26 kg/ha for the remaining 15 years. Until 1974, plots received only nominal quantities of K (5 kg/ha) as starter fertilizer. After 1974, four rates of K were applied—52, 112, 168, and O kg/ha. Soil N and C declined over time under both cropping systems. The original level of soil organic matter was 4.5%, and after continuous removal of only the grain from plots, the soil organic matter declined to 4.1%. Organic matter declined to 3.7% on plots from which all top growth was removed. Exchangeable K levels declined rapidly during the first few years of corn production and then stabilized with corn silage plots stabilizing at 71 ppm and corn grain plots at 100 ppm. Application of 26 kg/ha of P each year resulted in a rise in soil P. Soil acidity and lime requirements were directly related to the rate of N fertilization.
Characterization and Use of Food‐Processing Effluent for Forage and Beef Production1
Authors: Jung G. A. , Pearson G. A. , Fowler R. E. , Mitchell D. M. , Kocher R. E. , Quigley E. H.
Published: July 2010

Spray‐irrigating grass swards with food‐processing effluent on the Delmarva Peninsula creates the problem of grass accumulation. We hypothesized that spray‐irrigated grass would support a relatively high stocking rate of grazing cattle, and that the effluent would be a source of fertilizer nutrients and digestible energy for livestock. Four mixed orchardgrass (Dactylis glomerata L.) and tall fescue (Festuca arundinacea Schreb.) paddocks, each 0.202 ha, were rotationally grazed at monthly intervals summer and autumn for 2 years with steers or heifers, averaging about 300 kg. The cattle were fed ground corn (Zea mays L.) at 1% body weight/day. Small amounts of commercial fertilizer were needed periodically to stimulate plant growth. Enough aftermath grass was produced to support 7.4 head/ha in summer and autumn without loss of stand. Forage quality (crude protein, energy, and mineral content) was good throughout the grazing season, but better in autumn than in summer. Energy levels in autumn approached that of concentrates. With the exception of Ca content prior to application of gypsum, mineral element composition of grass in effluent‐irrigated pastures was much superior with regard to animal nutrition than that of untreated controls as well as grass grown elsewhere in the Northeast. Steers gained an average of 1.02 kg/day and totaled 1,075 kg/ha; heifers gained 0.65 kg/day and totaled 673 kg/ha in summer and autumn. Weight gains for a 55‐day period in autumn were 71% greater than those for a comparable period in summer. It was concluded that this highly productive ecosystem should be extensively used for animal production.
Fertilization Effects on Yield and N Concentration of Midland Bermudagrass1
Authors: Mathias E. L. , Bennett O. L. , Lundberg P. E.
Published: July 2010

A high yielding summer forage grass capable of with standing high temperatures and low moisture is needed in the northeastern U. S. ‘Midland’ bermudagrass( Cynodon dactylon (L.) Pers.) would meet these requirements, but production and management methods for the northeast need to be investigated.

Studies were conducted over 3 years at two locations in West Virginia to determine the effects of N and K rates on yields and N recovery of ‘Midland’ bermudagrass. Treatments consisted of factorial combinations of zero, 112, 224, and 448 kg of N and K/ha. Herbage was harvested two or three times at both locations each year, depending on the growing season. Herbage yield and N concentration of the herbage increased and percent recovery of the applied N decreased as N application rates increased. Oven‐dried forage yields reached 19,000 kg/ha when N was applied at 448 kg/ha. Yield, N concentration of forage, and percent N recovery varied in response to K application with K having little overall effect. Weed encroachment was enhanced by N application at one location, but not at the other location. Temperatures as low as −29 C were recorded with no apparent winter killing.

Soil pH decreased slightly with N application at one location, but not at the other. Available soil K correlated positively with K application rates and negatively with N application rates. Available soil Mg at both locations and available Ca at one location were decreased as N rates increased. Available soil Mg was decreased when K was applied at the zero N level, but otherwise, it was unaffected by K application.

These studies indicate that while N is necessary for maximizing herbage yield of ‘Midland’ bermudagrass, other factors such as location and soil type are important in determining persistence and longevity. Also, additional nutrients, such as Mg, need to be considered as N levels are increased.
Estimating Forage Yield with a Disk Meter1
Authors: Santillan R. A. , Ocumpaugh W. R. , Mott G. O.
Published: July 2010

The disk meter technique of estimating forage dry matter yields has been used by many researchers in recent years. However, few comparisons have been made on which size, weight, and technique of use gives the most precise results, or if species of grass has any effect on the results. A simple‐disk and a weighted‐disk were evaluated as techniques for estimating forage dry matter yield on several grasses. Predictions of dry matter yield were based on settling heights measured with the meters. Yield estimates were made on annual ryegrass (Lolium multiflorum Lam.) pastures, and swards of bahiagrass (Paspalum notatum Flügge), digitgrass (Digitaria decumbent Stent.), and limpograss [Hemarthria altissima (Poir.) Stapf et C. E. Hubb]. Separate linear regression relationships between dry matter yield and settling height were calculated (Y = bX). Correlation coefficients (r) of 0.79 to 0.99 with most r values exceeding 0.92 were found between height and dry matter yield. Standard deviations from regression ranged from 73.2 to 282.4 kg/ha for different sampling techniques, disk sizes, and grass types. Increasing the disk size (0.25 to 0.75 m2) increased the correlation and regression coefficients, and reduced standard error from regression. The largest disk provided contact with a greater area of biomass and resulted in yield estimates of greater precision, but the additional precision obtained by using the 0.75‐m2 disk over the 0.50‐m2 disk does not offset the reduced ease of use of the larger disk. In addition, the 0.25‐ and 0.50‐m2 disks gave more uniform b values across grasses than the other disks. Thus, one combined b value was found to adequately describe the relationship between settling height and dry matter yield for all four grasses with these two disks. These results substantiate that the disk meter is a useful, practical, and versatile instrument for estimating forage dry matter yield in small plots and grazed pastures. The simple‐disk meter proved to be equal to the weighted meter for predicting dry matter yield, however, the simple‐disk has the advantage over the weighted meter because it is much easier to use in the field.
Differential Susceptibility of Corn Cultivars to Zinc Deficiency1
Authors: Safaya N. M. , Gupta A. P.
Published: July 2010

Due to widespread deficiency of Zn in the northwestern plains of India, germplasm screening for identifying less susceptible cultivars of crop plants has become as essential as recommending proper methods of Zn fertilization. To study the relationship between differential susceptibility to Zn deficiency and nutrient composition of plants, 13 cultivars of corn (Zea mays L.) were grown in the greenhouse at 0 and 2.5 ppm of applied Zn, with uniform N‐P‐K rate, in 4‐kg lots of Zn‐deficient loamy sand of pH 8.5. After 45 days of growth, dry matter yield (DMY), and P, K, Ca, Mg, Fe, Mn, Cu, and Zn in the leaf, culm, and root fractions were measured. Significant cultivar differences in DMY and nutrient composition and the degree of their response to Zn were observed. The reduction in DMY of whole plants due to Zn deficiency ranged from 26.6% (‘Basi’) to 74% (White Opaque 2). However, the differential susceptibility of corn cultivars to Zn deficiency was not related to their Zn absorption characteristics. Zinc‐deficient plants revealed higher concentration of all nutrients (except Zn) in their tissues. The uptake of P was significantly higher in the shoots of Zn‐deficient plants. From regression analysis between the percent reduction in shoot DMY and the relative increase in the concentration of different nutrients in Zn‐deficient plants, only leaf and culm P concentrations were found to bear a high positive correlation (P<0.01) with the susceptibility index of cultivars. Relative increase in Fe concentration of shoots showed a positive correlation and in roots a negative correlation (P<0.05 for both) with the percent reduction in shoot DMY. These results show that the susceptibility to Zn deficiency in corn is intimately related to the P and Fe absorption and transport mechanisms.
Post‐Freeze Deterioration of Six Sugarcane Cultivars1
Authors: Gascho G. J. , Miller J. D.
Published: July 2010

Sugarcane (a complex trispecies hybrid, Saccharum spp) deteriorates following a killing freeze resulting in decreased sugar recovery with time. When the freeze is severe, sugarcane becomes unmillable. Cultivar differences in deterioration rates following freezes have been reported but most modern sugarcane cultivars have not been tested under field conditions. The main objective of this study was to compare the deterioration rates of six sugarcane cultivars during a 9‐week period following severe freezes at Belle Glade, Fla. 18 to 20 Jan. 1977. Samples of ‘CP 57‐603’, ‘CP 68‐1026’, CP 65‐357', CP 68‐1067', ‘Cl 41‐223’, and ‘CP 63‐588’ were randomly selected from the plots of a randomized complete block experiment each week. Brix, raw juice pH, titratable acidity, stalk weight, and juice polarization were measured. Theoretical yield of sugar per metric ton of cane, percent juice sucrose, percent purity, and sugar loss with time were obtained by standard calculations. Deterioration rates were estimated by regression of sugar parameters with time. All cultivars deteriorated rapidly and linearly over the 9‐week period following three nights of freezes (the lowest temperature was −6 C). The average loss in theoretical sugar yield was 13 kg of suagr/metric ton of cane/week. The rate of deterioration for the 9‐week period, as gauged by the data collected, was lowest for CP 65‐357. During the first 5 weeks following the freezes, theoretical sugar yield and purity were highest for CP 63‐588; however, during the final weeks of the experiment, juice quality was highest for CP 65‐357. The mean loss of sugar for all cultivars was 9.2% per week.