bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Source and Rate of Nitrogen on N Uptake and Fertilizer Efficiency by Spring Wheat and Barley1
Authors: Alessi J. , Power J. F.
Published: July 2010

Field experiment was conducted to determine the effect of fertilizer N source and rate on N uptake and recovery by small grains. Five N sources — NH4NO3, (NH4)2SO4 Ca(NO3)2, Uramite, and Nitroform (urea‐formaldehyde) — were applied to Temvik silt loam for 4 years at rates of O, 34, and 68 kg N/ha to spring wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) under an annual dryland cropping system. Residual responses were measured until effects were no longer significant. N content of plants was usually increased at all stages of growth by all N sources; N uptake was greatest for the ammonium and nitrate sources at the 68‐kg rate. At the end of the residual period, recoveries averaged 78% for the ammonium anl nitrate sources, and 44% for the urea‐formaldehyde materials. Recoveries increased by 12 to 29% during the residual period, with the greatest increase occurring for the calcium nitrate treatment. Highest average N recovery for the 8‐year period was 87% for Ca(NO3)2. No accumulation of NO3‐N remained in the upper 180 cm of soil at the end of the experiment.

Results from this long‐term study indicate that ammonium and nitrate sources of fertilizer N are superior to urea‐formaldehyde for small grain production in semiarid regions.
Influence of Planting Method and Plant Population on Cotton (Gossypium hirsutum L.)1
Authors: Bridge R. R. , Meredith W. R. , Chism J. F.
Published: July 2010

To determine the effects of variations in plants/hill, within‐row plant spacings, and plant populations on the agronomic and fiber properties of cotton (Gossypium hirsutum L.), we evaluated the performance of ‘Deltapine 16’ when planted in hills and drilled at five populations over a 3‐year period (1969‐71). Hills were spaced 38 cm apart. The hills were thinned by hand to one, three, five, seven, and nine plants/hill, representing a range in population of 24,700 to 222,300 plants/ha. Plants in the drill plantings were spaced approximately 38.0, 12.7, 7.6, 5.3, and 4.3 cm apart to provide approximately the same populations for the hill‐dropped and drill‐planting method.

Significant differences in yield due to populations were found, but planting method had no significant influence on yield. The highest yields each year were obtained in a population range of 70,000 to 121,000 plants/ha. In 2 out of 3 years the highest yields were obtained with a population of 114,000 to 121,000 plants/ha (five plants/hill or plants spaced 7.6 cm apart). Significant differences in lint percentage, boll size, and seed index were due to populations. The combined data indicate no appreciable differences in lint percentage; lint percentage of the low population, however, was significantly higher than that of the two highest populations in 2 of the 3 years. Boll size gradually decreased as plant population increased, with the lowest population usually producing significantly larger bolls and seed.

We found that plant populations had no consistent effects on fiber length, strength, and elongation. The differences were small in magnitude and of no practical value. Micronaire tended to decrease as population increased.
Forage Production on Bermudagrass Sods Overseeded with Tall Fescue and Winter Annual Grasses1
Authors: Fribourg Henry A. , Overton Joseph R.
Published: July 2010

Bermudagrass (Cynodon dactylon), widespread in Tennessee, furnishes forage from April to October and is dormant during the remainder of the year. This study was conducted to determine whether the season of forage production from such dormant sods could be extended by overseeding annual and perennial cool‐season grasses, and to determine their effects on warm‐season grass production. Established sods of common and ‘Midland’ bermudagrasses growing on Loring, Grenada, and Falaya soils were overseeded in 50‐cm rows in October 1965, 1966, and 1967, after bermudagrass growth had stopped, with ‘Monon’ wheat (Triticum aestivum L.), ‘Blount’ oats, (Avena sativa L.), ‘Balbo’ rye (Secale cereale L.) and Italian ryegrass (Lolium spp.). ‘Kentucky 31’ tall fescue (Festuca arundinacea Schreb.) was seeded in 50‐cm rows in October 1965 and 1966 and in 25‐cm rows in 1967. Summer production of bermudagrass grown alone, which ranged between 6 and 10 t/ha of dry matter, was depressed by annuals seeded the previous autumn. Overseeded small grains clipped during winter produced 1.4 to 3.0 t/ha dry matter and wheat harvested at late boot furnished 3.5 to 4.4 t/ha. Ryegrass yielded 3.5 to 5.0 t/ha during late winter and spring. Overseeding of the annual species resulted in higher total yields per unit area each year and extended the length of time forage was growing and available. Excellent stands of tall fescue were obtained and maintained through 1972. Fescue decreased Midland bermudagrass production by about 30%, and that of common by about 40%. However, fescue production in spring, summer, and fall compensated for the decreased bermudagrass production, increased total yearly forage production by about 2 t/ha, and extended the potential grazing season from 5 to 8 to 9 months.
Elemental Composition and Response to Nitrogen of Sunflower and Corn1
Authors: Robinson R. G.
Published: July 2010

The reason for the research was to learn the elemental composition of sunflower (Helianthus annuus L.) and to measure the crop's response to nitrogen and irrigation. Comparative performance of corn (Zea mays L.) and sunflower in yield, response to fertilizer, and removal of nutrients from the soil is of interest because sunflower is a new crop on many corn‐growing farms.

The objective was to compare sunflower and corn in yield, elemental composition, response to nitrogen fertilizer, and removal of nutrients from the soil. The crops were grown on silt loam soil with and without nitrogen applied at various times and on sandy soil with and without nitrogen and irrigation.

Nitrogen at 75 or 150 kg/ha failed to significantly increase yield of either crop on fertile silt loam soils. On droughty sand, nitrogen at 224 kg/ha increased sunflower yield, but both irrigation and nitrogen were needed to significantly increase corn yield.

Treatments within a trial did not affect elemental composition except where treatment altered yield.

Sunflower achenes and vegetative parts had greater concentrations of most elements than did corn. However, the higher yield of corn offset this and resulted in greater soil depletion of most elements.

Concentrations are given of N, P, K, S, Ca, Mg, Na, Sr, Al, Fe, Zn, Cu, Mo, Mn, and B in corn and sunflower stems and leaves in prebloom stage and in mature sunflower achenes, sunflower stover, corn caryopses, and corn stover.

Sunflower yields were 35 to 40% those of corn under favorable soil fertility and moisture conditions. This research indicates that sunflower ranks below corn as a soil‐depletive crop.
Flooding and Soil Temperature Effects on Wheat During Grain Filling1
Authors: Luxmoore R. J. , Fischer R. A. , Stolzy L. H.
Published: July 2010

The root environment of wheat (Triticum aestivum L. em Thell) was modified with flooding and soil temperature treatments during the grain filling stage in an assessment of the relation between root respiration and grain yield. Short term flooding (10 to 15 days) at 15 to 17C soil temperature in a pot and field experiment did not influence yield. Longer term flooding (20 to 30 days) reduced yield by 15 to 23% at 15 to 17C soil temperature and by 73% at 25C soil temperature. Yield reduction was associated with smaller mean grain weight. At 5C soil temperature 30 days of flooding had no significant effect on yield. Stem dry weight per tiller decreased by about 95% with increase in soil temperature from 5 to 25C for both flooded and nonflooded treatments. Mathematical simulation estimates of root respiration applied to the experimental conditions indicated that roots were a minor sink for assimilate during the grain filling stage. Root environmental effects on wheat yield could not be interpreted in terms of roots being competitive with the developing grain for photosynthate. The significant effects of soil conditions on the maturing wheat plant indicate some importance of roots and root environment during the grain filling stage.
Grain Yield, Milling Quality, and Seed Viability of Rice as Influenced by Time of Nitrogen Application and Time of Harvest1
Authors: Seetanun W. , De Datta S. K.
Published: July 2010

Since the development of high yielding tropical rice (Oryza sativa L.) cultivars like ‘IR8,’ attention has turned to the differences in grain quality among rice cultivars. In field experiments at the IRRI farm, we studied the optimum time for applying nitrogen to rice cultivars for maximum grain yield, highest milling yield, and maximum seed viability. We applied ammonium sulfate at 60 kg/ha N in the 1969 wet season and 150 kg/ha N in the 1970 dry season. We used the cultivars IR8, ‘IR20,’ ‘C4‐63,’ and ‘RD1’ in the 1969 wet season and IR8, IR20, ‘IR22,’ and RD1 in the 1970 dry season. Farmers in South and Southeast Asia grow these cultivars on millions of hectares.

Split application of nitrogen increased grain yield over single basal application in some cultivars by minimizing lodging.

Topdressing of nitrogen at heading increased the percentage of head rice (unbroken polished grains) which was associated with higher protein content under that treatment. IR22, whose percentage of head rice was higher than those of the other cultivars tested, showed no further increase in head rice with nitrogen topdressing.

Based on maximum grain yield with highest milling recovery and seed viability, the best time for harvesting transplanted rice was between 30 and 42 days after heading in the wet season and between 28 and 34 days after heading in the dry season.
Storage of High Moisture Grain Sorghum [Sorghum bicolor (L.) Moench] Treated with Propionic Acid1
Authors: Nelson L. R. , Cummins D. G. , Harris H. B. , Baird D. M.
Published: July 2010

This study was designed to determine if propionic acid can be used as a preservative for storage of high moisture sorghum [Sorghum bicolor (L.) Moench] grain. Sorghum grain at 16, 21, and 26% moisture levels was treated with 0.75% propionic acid by weight, and treated and untreated samples of each moisture level were stored in polyethyline lined garbage cans for 60 days. The untreated 21 and 26 moisture level samples heated while the untreated 16% moisture sample or the 16, 21, 26% moisture samples treated with propionic acid did not heat. After 60 days in storage, untreated grain stored at 21 and 26% moisture had molded and was badly deteriorated. No evidence of molding was observed in any of the propionic acid treated samples and only slight evidence of molding was observed in the untreated 16% moisture sample. Significant differences among samples for in vitro dry matter digestibilities were not observed. Unspoiled grain samples (16% moisture untreated, and 16, 21, and 26% moisture samples treated with propionic acid) were fed to feeder pigs for intake and gain evaluation. The highest feed intake was for the 26% moisture propionic acid treated sample and the rations containing the 21 and 26% moisture grain treated with propionic acid produced the highest average daily gains in weight. It was concluded that high moisture sorghum grain can be stored successfully as a feed grain after treatment with propionic acid.
Canopy Temperatures of Barley as Influenced by Morphological Characteristics1
Authors: Ferguson Hayden , Eslick R. F. , Aase J. K.
Published: July 2010

Canopy temperature under a set of environmental conditions is an integrated result of the energy absorption and dissipation mechanisms acting within the canopy. The relative magnitude of these various mechanisms may affect the amount and efficiency of water use. We studied the influence of different morphological features such as plant color, awn length, and waxiness on canopy temperatures of field grown barley (Hordeum vulgare L.). Morphological differences were obtained by using barley lines isogenic for the various features. Canopy temperatures were measured with an infrared thermometer on five different dates within a 21‐day period after heading. Light‐colored plants were significantly cooler (5% level) than normal‐colored plants. Awn length significantly (5% level) affected canopy temperatures of a sixrow variety; awned canopies were cooler than awnless. Awn length did not affect the canopy temperatures of a two‐row variety. Waxiness did not affect canopy temperatures. Calculations indicate that differences in canopy temperatures due to plant morphology could significantly affect water use.
Nitrogen Requirements of Winter Wheat (Triticum aestivum, L.) Varieties ‘Blueboy’ and ‘Redcoat’1
Authors: Stanford George , Hunter Albert S.
Published: July 2010

In 1970–71, five N‐rate field experiments were conducted with fall‐seeded soft red winter wheat (Triticum aestivum, L.) on limestone‐derived soils in Pennsylvania. Varieties ‘Blueboy’ and ‘Redcoat’ were compared at two locations. At three locations, only Blueboy was grown. Redcoat is widely grown in Pennsylvania, but Blueboy was only recently introduced. The relative nitrogen requirements of these varieties, therefore, was essentially unknown when these studies were begun. Fall and spring applications of 0, 34, 67, 101, 135, and 168 kg/ha of N as ammonium sulfate were compared at each location. The nitrogen content of grain plus straw associated with maximum attainable yield of dry matter was similar among locations and varieties, the mean percent N and its standard deviation being 1.38 ± 0.06%. Yields of grain invariably were depressed when nitrogen in grain plus straw exceeded the mean value of 1.22 ± 0.06% (S.D.). The latter value is considered to represent the internal N requirement of the wheat associated with optimum production of grain, and it corresponds to the percent N in grain plus straw associated with 95 to 98% of total dry matter production.

Recovery of fertilizer N was significantly greater for spring than for fall applications, although differences were small (means were 56 and 48%, respectively, for all locations). Yields of Blueboy were substantially greater than those of Redcoat at locations where these varieties were compared. Interactions of rate and time of N application on yields of grain and dry matter and N yields were not significant. Total uptake of N required per unit of wheat grain for maximum attainable yield is almost twice that required for corn.
Botanical Composition of Subclover‐Grass Pastures as Affected by Single and Dual Grazing by Cattle and Sheep1
Authors: Bedell T. E.
Published: July 2010

Since cattle and sheep tend to prefer different forage species and since little information has been available upon which to design successful grazing programs for western Oregon dryland improved pastures, a grazing experiment was conducted to determine the effects of several combinations of cattle and sheep use on forage species composition and livestock performance. Improved pasture mixtures of ‘Nangeela’ subterranean clover (Trifolium subterraneum L.) with ‘Oregon’ perennial ryegrass (Lolium perenne L.) and with ‘Alta’ tall rescue (Festuca arundmaeea Schreb.) were grazed by cattle and sheep alone and in several combinations during the spring‐summer seasons of 1967, 1968, and 1969. Seasonal botanical composition of both forage mixtures was influenced markedly by the kind of grazing treatment. The subclover component, necessary in order to sustain high forage production, declined both within and progressively among seasons in the sheep‐alone and low cattle:high sheep, dual use treatments. Grazing cattle selected grasses whereas sheep selected subclover as long as forage of the preferred species was abundant. Grazing cattle alone, or a relatively high proportiton of cattle:sheep, tended to hold grasses in check allowing more subclover to prevail longer into the grazing season. This contributed to higher per acre animal performance and to a higher proportion of subclover in the succeeding year.
Response of Coastal Bermudagrass to Soil Applied Sulfur, Magnesium, and Potassium1
Authors: Landua D. P. , Swoboda A. R. , Thomas G. W.
Published: July 2010

A pot experiment was conducted using several acid sandy soils of Texas to determine their sulfur and magnesium requirements and the rapidity with which these elements can become limiting when using 400 ppm N and 200 ppm P. Potassium was applied at the rate of 50, 200, and 400 ppm K.

Yield of Coastal bermudagrass (Cynodon dactylon (L.) Pers.) was significantly increased (1% level) by the application of 32 ppm S. Magnesium at the rate of 48 ppm Mg and potassium above the rate of 50 ppm K did not affect yield significantly until the third harvest.

Sulfur content of the forage was increased only by the application of S. Magnesium content was increased by the application of Mg, but was decreased by the application of S and K. Potassium content was increased by the application of K and S and decreased by the application of Mg.
Rainout Shelter and Drainage Lysimeters to Quantitatively Measure Drought Stress1
Authors: Teare I. D. , Schimmelpfennig H. , Waldren R. P.
Published: July 2010

A modern rainout shelter designed to open and close with an improved electronic control sytsem and to withstand high winds is described. It was installed in conjunction with drainage lysimeters to quantitatively evaluate evapotranspiration, physiological indicators of drought stress, and irrigation scheduling.
Protein, Crude Fiber, Tannin, and Oxalate Concentrations of Some Introduced Astragalus Species1
Authors: Davis A. M.
Published: July 2010

A collection of Astragalus accessions was grown for seed increase and preliminary evaluation at Wawawai, Washington. This presented a unique opportunity to evaluate them for forage quality components. Those selected were: concentration of protein (N ✕ 6.25), crude fiber, tannin, and oxalate; and presence or absence of alkaloids.

Analyses of the 46 Astragalus accessions, representing 33 species and four unidentified accessions, showed a ranged of 9.8 to 21.7% protein, 15.5 to 33.9% crude fiber, .05 to 20.3 mg/g tannin and .44 to 2.66% oxalates. Species with more than 18% protein and less than 28% crude fiber (i.e., equal to good alfalfa (Medicago sativa L.) hay) and acceptable levels of oxalates and tannins were: A coluteocarpus Boiss., A. dactylocarpus Boiss., A. galegiformis L., A. peduncularis Royle, A. tephrosioides Boiss., and one unidentified accession (P. I. 314361). The only species having measurable amounts of alkaloids was A. calycinus Bieb.
Activity of Barley Seedling Roots as Measured by Strontium Uptake1
Authors: Soileau J. M.
Published: July 2010

Root activity at various depths in soils is important in relation to effective use of lime and fertilizers by crops. Barley (Hordeum vulgare L.) seedlings were grown in presplit cylinders in the greenhouse to measure root activity in three 10‐cm soil depth zones and to estimate daily rates of nutrient uptake. Twenty‐five seedlings were planted per 15 ✕ 30 cm cylinder containing 6.5 kg of soil. SrCO3 was applied to one of the 10‐cm layers of soil, and the plants were sequentially harvested for measurement of Sr uptake and root growth. A substantial number of roots penetrated to the 20 to 30 cm zone in 14 days. After 31 days, total root length was 662 m, distributed uniformly throughout the soil column. Root activity index calculations based on Sr uptake in tops per unit length of roots indicated that the 0 to 10 cm layer was the most active root zone over a 31‐day period. Total uptake of St, Ca, Mg, and P by barley tops increased linearly with increase in total root length or dry weight. Mean daily rates of uptake of Ca, Mg, and P (μg/m of roots/day) showed a general decrease with time. Milliequivalent concentration ratios of Ca to Sr in barley tops were much lower than ratios of exchangeable Ca to exchangeable Sr in the soil.
Flue‐Cured Tobacco Yield and Oxygen Content of Soil in Lysimeters Flooded for Various Periods1
Authors: Campbell R. B.
Published: July 2010

Tobacco (Nicotiana tabacum L. var. ‘Coker 298’) plants grown in lysimeters were flooded for 0, 12, 24, 48, 96, and 120 hours to define more clearly 02‐depletion rates in soil and effects of flooding on growth. The 02 content of air entrapped in soil pores was monitored with membrane‐covered galvanic‐type probes before, during, and after a 96‐hour flooding. Oxygen decreased from 16 to less than 4% in the soil atmosphere within 24 hours after flooding. Upon drainage, 02 increased within 48 hours to the original concentration.

Growth and yield differences between the control and 12‐ and 24‐hour flooding treatments were not significant. Flooding for longer than 48 hours significantly reduced yield to less than 40% of that of the unflooded plants. Plants were more susceptible to flood damage at the 12‐ leaf stage of development than at the 17‐leaf stage. Reducing sugars increased from 11.8 to 14.8% and total alkaloids decreased from 1.26 to 0.76% in tobacco leaves flooded for 24 hours.
Influence of Temperature and Moisture Stress from Sodium Chloride Salinization on Okra Emergence1
Authors: Albregts E. E. , Howard C. M.
Published: July 2010

Okra (Hibiscus esculentus L.) seed were planted in a Scranton fine sand soil at 20, 25, and 30 C with six levels of moisture stress, 1.18, 1.75, 2.41, 4.33, 5.90, and 10.84 atm. Moisture stress was obtained by varying the moisture level in the soil and by NaCl salinization. The emergence rate and fresh plant weight decreased as the temperature decreased and soil moisture stress increased. The optimum temperature and soil moisture stress for total and earliness of emergence was 25 to 30 C and 1.18 atm. No emergence occurred at 10.84 atm of moisture stress and total emergence was reduced only at 5.90 atm and 20 C.
Partitional Analysis of Grain Yield from Different Shoots as Influenced by Nitrogen in Finger Millet1
Authors: Krishnamurthy K.
Published: July 2010

Pattern of grain yield contribution from different tiller groups in relation to nitrogen levels was investigated in finger millet (Eleusine coracana L. Gaertn, var. ‘H‐22’) in a 2‐year field trial. There was linear increase in grain yield (7 to 26 g/plant) with increasing levels of nitrogen (0 to 90 kg/ha). These differences in grain yield were mainly related to the total number of shoots produced (4.0 to ll.9/plant), and particularly to those produced during the first 27 days (2.1 to 8.7/plant). Nitrogen also increased the grain yield contribution (38 to 52%) from the early season tillers. The final grain yield and the number of shoots produced within 5 weeks of transplanting were related. The main axis contributed 24%, whereas early, intermediate, late, and secondary tiller groups provided 47, 16, 8, and 5%, respectively, to the total grain yield per plant (17 g). In a similar manner, these groups of shoots contributed 15, 40, 21, 14, and 10%, respectively, to total ear number per plant (6.9).
Effects of N, K, and Cl on Nitrogen Components of Russet Burbank Potato Plants (Solanum tuberosum L.)1
Authors: Murarka I. P. , Jackson T. L. , Moore D. P.
Published: July 2010

Although it is generally recognized that Cl− may reduce nitrate uptake by plants, little is known about the effects of Cl− or cation‐anion balance on the various N fractions in plants. The effects of rates of N, K, and Cl fertilizers and N‐K‐Cl interactions on total N, nitrate N, and protein N in potato (Solanum tuberosum L.) plants were studied in the greenhouse to provide a basis for evaluating by chemical analysis their influence on the N status of plants.

Both the concentrations and the total amounts of N, nitrate N, and protein N were significantly increased by N rates up to 200 ppm. The total N uptake was increased by K fertilization but the concentrations of N, nitrate N, and protein N were decreased from the dilution effects of increased growth. Cloride application at 100 or 200 ppm significantly decreased the total amounts of N and nitrate N in the top but did not affect the total amount or the concentration of the protein N fraction. These findings support the conclusion that chloride may compete with nitrate uptake and with accumulation of NO3− but apparently does not interfere with conversion of N to protein. Through its influence on cation‐anion balance, high chloride may lead to plant tissues that are low in nitrate even though the plant is adequately supplied with N.
Influence of Temperature Change at Bud on Composition of Alfalfa at First Flower1
Authors: Greenfield P. L. , Smith Dale
Published: July 2010

Alfalfa (Medicago sativa L., cv. ‘Vernal’) plants were grown to bud in three temperature regimes, H (33/24 C, day/night), W (27/18 C), and C (21/12 C), and then part of the plants in each chamber were switched to the other regimes and grown to first flower. When plants were retained in the same regime to first flower, days to bud and first flower, dry weight of plant parts, total nonstructural carbohydrate (TNC), and in vitro digestible dry matter (IVDDM) percentages in plant parts increased with a decrease in temperature, whereas concentrations of P, Zn, and Mn in the herbage decreased with a decrease in temperature. Concentrations of N, K, and Fe were highest and similar in the herbage retained in the H and W regimes and lowest in the C regime. However, concentrations of Ca, Mg, Ba, Sr, and B in the herbage were highest in plants retained in the H regime, and lowest but similar in plants retained in the W and C regimes.

A change to a cooler temperature between bud and first flower generally delayed flowering, increased dry weights of plant parts and the percentages of TNC and IVDDM in these parts, and decreased concentrations of minerals in the herbage. Change to a warmer temperature had the opposite effect. Concentrations of TNC, IVDDM, and minerals in the herbage at first flower were influenced most by temperature between bud and first flower, but root TNC percentage at first flower was influenced both by temperature prior to bud and by temperature from bud to first flower. Percentages of TNC and IVDDM in the herbage at first flower were highly correlated (r=0.93). The most dramatic changes in TNC percentages in response to temperature change occurred in leaflets. Changing temperature from H to C at bud increased the TNC percentage in leaflets by 121% as compared with plants held in the H regime. In contrast, changing from C to H at bud decreased TNC percentage in leaflets by 62% as compared with plants held in the C regime. From a practical viewpoint, alfalfa herbage harvested after a cool period of weather should have a greater energy feeding value and silage fermentation capacity than herbage harvested after a warm period.
Cow and Calf Gains on Ladino Clover‐Tall Fescue and Tall Fescue, Grazed Alone and with Coastal Bermudagrass1
Authors: Burns J. C. , Goode L. , Gross H. D. , Linnerud A. C.
Published: July 2010

Cows and calves were used in a 2‐year study to determine the quality, as measured by calf gains, of tall fescue (Festuca arundinacea) pasture, with and without ladino clover (Trifolium repens) grazed alone or in combination with ‘Coastal’ bermudagrass (Cynodon dactylon (L) Pers.). Pastures were managed to limit any adverse influence of forage quantity or quality on calf gain.

Gain per calf was highest on ladino‐tall fescue (L‐TF) pastures during the entire trial. In period 1 (initiation of grazing until May 31) calves on tall fescue (TF) averaged 6 kg/head less than those grazing L‐TF (43.3 vs 37.3 kg). During the critical summer months calves on the L‐TF + Coastal bermudagrass (CB) and TF + CB systems averaged 73.1 and 68.3 kg/head, respectively, compared with 79.9 kg for L‐TF. Total seasonal gains from the L‐TF treatment averaged only 4 kg/head more than the L‐TF + CB system (122.1 vs 118.1). Although seasonal calf gains from the TF + CB system were lower (105 kg/head) than L‐TF + CB, they were acceptable (0.68 kg/head per day) and justify quantitative evaluation of a pure grass system.
Production of Six Tropical Legumes Each in Combination with Three Tropical Grasses in Florida1
Authors: Kretschmer Albert E. , Brolmann J. B. , Snyder G. H. , Gascho G. J.
Published: July 2010

Summer production of permanent grass pasture in southern Florida varies depending on the quantity of fertilizer N applied. Generally, commercial production is excessive even ,with minimum applications of N. Crude protein contents, however, are low because of rapid grass growth and concomitant dilution of the N. Because white clover (Trifolium repens L.) or other temperate legumes do not grow during the summer, an alternative possibility for increasing pasture quality is the inclusion of tropical legumes in permanent grass pastures.

A small‐plot clipping experiment was designed to compare various tropical grass‐legume mixtures with grasses grown alone and receiving different rates of N fertilization. Comparisons were based on dry matter and crude protein yields and percentages.

Each of the following legumes, Stylosanthes humilis HBK., Indigofera hirsuta Linn., ‘Hairy Indigo;’ Phaseolus atropurpureus DC., ‘Siratro;’ Desmodium intortum (Mill.) Urb., ‘Greenleaf;’ D. heterocarpen (Linn.) DC.; and Glycine wightii Willd., ‘Clarence,’ was grown in combination with Digitaria decumbens Stent., ‘Pangola’ digitgrass; Paspalum notatum Flugge., ‘Pensacola’ bahiagrass; and Setaria anceps Stapf., ‘Nandi.’

Yields and N contents are reported for a 2‐year period. Setaria‐legume combinations generally were inferior to those of other grass‐legume mixtures. D. intortum‐grass mixtures produced 12,430 kg/ha of dry matter annually compared with 9,400 for Pangola and 5,740 for bahiagrass growing alone and fertilized with 126 kg/ha per year. Crude protein contents of harvested mixtures were higher than those for grasses alone that received N at the rate of 126 kg/ha.

Crude protein yields of D. intortum‐Pangola mixtures were about three and a half times those for Pangola and five times those for bahia alone with the 126 kg/ha N rate. Average dry matter yield of the S. humilis‐grass mixtures was equal to those for average Siratro‐ and D. heterocarpon‐pon‐grass mixtures, but crude protein yield of S. humilis mixtures was less. Dry matter and crude protein yields of I. hirsuta and G. wightii mixtures were consistently less than those of other legume mixtures.
Implicit Estimate of Residual Nitrogen Under Fertilized Range Conditions in the Northern Great Plains1
Authors: Stauber M. S. , Burt Oscar R.
Published: July 2010

Information concerning carryover of fertilizer nitrogen in the plant‐soil system is necessary to determine optimum fertilizer policies for dryland grasses in semiarid regions. A primary contribution of this paper is the presentation and illustration of a dynamic model for estimation of carryover nitrogen. The carryover relationship is estimated implicitly through yield response as opposed to direct measurements on nitrogen. Data from an experiment designed to evaluate the effects of nitrogen and phosphorus fertilizers and seasonal precipitation on the yield and composition of bromegrass (Bromus inermis)‐crested wheatgrass (Agropyron cristatum) hay were analyzed with the model. A polynomial yield response equation in the two variables, plant‐available nitrogen and seasonal precipitation, was estimated simultaneously with a first order difference equation assumed to describe the residual nitrogen relationship.

Statistical estimation was by nonlinear regression techniques. The proportion of nitrogen available in year t which was carried over to year t+1 was estimated at approximately 54%, taking precipitation at the mean of a 32‐year series, and the standard error associated with percent carryover was 3.4. A maximum yield of 2072 kg/ha (1849 lb/acre) resulting from 268.99 kg/ha (240 lb/acre) of available nitrogen is predicted under average precipitation conditions. The fact that an economic determination of the optimal level of nitrogen to maintain in the soil must include a consideration of carryover and the relevant interest rate is demonstrated. In equilibrium the optimal level of nitrogen is 89 kg/ha (79 lb/ acre), assuming an interest rate of 10%, a forage value of $.0165/kg ($15/ton), and a nitrogen fertilizer cost of $.22/kg ($.10/lb) with the costs of spreading fertilizer ignored. The maintenance of this level of nitrogen in the soil would increase average net returns over unfertilized grass by $2.27/ha or by about 20%.
Sorghum Growth and Nutrient Uptake in Relation to Soil Fertility, II. N, P, and K Uptake Pattern by Various Plant Parts1
Authors: Roy R. N. , Wright B. C.
Published: July 2010

An understanding of seasonal nutrient accumulation patterns under varying fertility levels is important for planning an efficient fertilization program. Field experiments were conducted to determine the effects of varying rates of N (0, 60, and 120 kg/ha) and P (0 and 26 kg/ha) on the N, P, and K accumulation pattern by various plant parts of a sorghum [Sorghum bicolor (L.) Moench] hybrid. Plant samples were collected at weekly intervals, partitioned into plant parts, and analyzed for N, P, and K.

Nitrogen and P accumulation by whole plants increased almost linearly until maturity, but K accumulation was more rapid early in the season. A significant loss of K from the whole plant (and head) occurred during the last week. Nitrogen, P, and K accumulation rates were higher during the 35th to 42nd day and 70th to 91st day which coincided with the peak vegetative growth period and the grain‐filling stage, respectively. In unfertilized plants relatively higher translocation of N and P from the vegetative parts to the developing grain occurred. Little K was translocated. A much smaller percentage of total K was found in the head and more K accumulated in the stem than N and P.

Application of 60 kg N/ha significantly increased N, P, and K yields of whole plant by 60.9, 49.4, and 19.1%, respectively. Further respective increases were 19.0, 18.9, and 12.3%, with 120 kg N/ha. Respective increases were 28.6, 49.0, and 17.1% with 26 kg P/ha over no phosphorus.
Beef Production on Bromegrass (Bromus inermis Leyss.) Pastures Fertilized with Anhydrous Ammonia1
Authors: Lechtenberg V. L. , Rhykerd C. L. , Mott G. O. , Huber D. A.
Published: July 2010

Smooth bromegrass (Bromus inermis Leyss.) pastures were fertilized with anhydrous ammonia at 0, 112, 224, and 448 kg N/ha to determine the effectiveness of anhydrous ammonia as an N fertilizer on pastures and to determine the effect of high rates of N fertilization on seasonal trends in percent nitrate nitrogen (NO3‐N) and percent in vitro dry matter disappearance (IVDMD) of pasture herbage. A rotational grazing system was used with four tester animals per paddock. Additional animals were available, when needed, to graze the excess herbage.

Anhydrous ammonia was as effective in increasing animal production per hectare as was ammonium nitrate at the same application rate. Nitrate‐N concentrations as high as 0.25% were obtained in early spring with the highest N application rates. No animal disorders were observed. Level of N fertilization had no effect on percent IVDMD. Both percent IVDMD and percent NO3‐N were high in early spring, declined during the initial portion of the grazing season, and then increased during the later part of the season. Nitrogen fertilization affected the seasonal trend in NO3‐N but not in percent IVDMD.
Yield Components and Quality of Siratro‐Kleingrass Association1
Authors: Siewerdt Lotar , Holt Ethan C.
Published: July 2010

An examination of the potential of a tropical legume to contribute improved forage production and quality as well as nitrogen (N) to a grass‐legume association was undertaken. ‘Siratro’ (Phaseolus atropurpureus D.C.) and ‘Kleingrass 75’ (Panicum coloratum L.) were chosen for study based on their reported performance. Siratro, introduced from Australia, was grown in association with Kleingrass 75, cut at different frequencies, and the contribution to dry matter (DM), crude protein (CP) content and in vitro digestible dry matter (IVDDM) was determined. Yield increased with less frequent cutting the first year, but no residual effects of cutting frequency were evident in the second year when all plots were cut uniformly. The mixture exceeded either the grass or the legume alone in yield. Siratro and Kleingrass 75 contributed equally to the association at the 3 and 5‐week cutting frequencies but Siratro made up 58% of the sward at the 7‐week frequency. Siratro was consistently high in CP whereas the grass alone and grass components declined with age. Siratro and Kleingrass were equal in % IVDDM at the youngest age, but the IVDDM of the legume remained constant with age whereas IVDDM declined with age in grass. Thus, the forage mixture was higher in crude protein and digestibility than the grass alone.
Effects of Clipping on Carbohydrate Reserves in Basin Wildrye1
Authors: Perry L. J. , Chapman S. R.
Published: July 2010

Basin wildrye (Elymus cinerus Scribn. and Merr.) plants are difficult to maintain under spring grazing conditions. The objective of this study was to determine whether an association between carbohydrate reserve depletion and regrowth following clipping occurs in basin wildrye.

After establishment, individual, spaced basin wildrye plants were clipped to 10 or 30 cm at three developmental stages in 1971. Total nonstructural carbohydrates (TNC) were measured on these plants 1, 2, 3, and 10 weeks following the initial clipping, and on additional plants, TNC was measured on regrowth of 3 weeks after each initial clipping. Seasonal TNC trends of undipped plants were also determined.

Seasonal TNC levels of undipped plants declined rapidly during June. After this time, TNC levels increased through the summer, except for a decline in mid‐August associated with the following year's tiller development. Carbohydrate reserves (TNC) of plants clipped once or twice to 10 cm were significantly lower than for plants clipped to 30 cm at all three developmental stages at all dates. The greatest decline was associated with plants clipped twice to 10 cm. Within 3 weeks TNC was restored with plants clipped to 30 cm, but only slight restoration occurred with plants clipped to 10 cm. Ten weeks after the initial clipping, TNC levels of plants clipped to 10 cm were significantly lower than those of plants clipped to 30 cm.

These results indicate that a severe depletion of carbohydrate reserves occurs following clipping. This may be associated with lack of resistance to spring grazing of basin wildrye.
Response of Soybeans Following Six Annual Applications of Various Levels of Boron, Copper, and Zinc1
Authors: Martens D. C. , Carter M. T. , Jones G. D.
Published: July 2010

Relatively high levels of micronutrients are applied to some soils as fertilizers, fungicides, or waste products. Experimental data are needed to determine whether these micronutrient applications cause yield decreases or accumulations of micronutrients in edible plant portions. In this research, field investigations were conducted on Davidson clay loam and Marlboro fine sandy loam to determine tolerable levels of B, Cu, and Zn applications for soybeans [Glycine max (L.) Merr.]. Various levels of the micronutrients were applied to the two soils annually for 5 years preceding this investigation and for a sixth year prior to growing the soybeans under study. Neither soybean plant growth nor seed yield was decreased where as high as 3.3 kg B, 8.4 kg Cu, and 11.1 kg Zn/ha were applied to the soils annually for 6 years. This relatively high tolerance of soybeans to B, Cu, and Zn applications was attributed partly to a decreased untake of the micronutrients at the near‐neutral levels of pH in the soils. Evidence was presented indicating that the six annual applications of B, Cu, and Zn did not increase the concentrations of the micronutrients in soybean seed to levels that would preclude their use as animal feed.
Effects of Burning on Soil Temperature and Yield of Coastal Bermudagrass1
Authors: Monson Warren G. , Burton Glenn W. , Williams E. Jay , Butler James L.
Published: July 2010

Early spring burning of ‘Coastal’ bermudagrass (Cynodon dactylon (L.) Pers.) sod is a recommended practice for control of the 2‐lined spittlebug (Prosapia bicincta (Say) plant diseases, and winter weeds. This study was designed to determine effects of time of burning on dry matter yield, soil temperature, and forage quality. Coastal bermudagrass sod was burned at 2‐week intervals between mid‐February and late March for 6 years. When sod was burned about March 1, the average dry‐matter yield of Coastal bermudagrass was increased by 1,000 kg/ha over that of the unburned check plots. Digestibility and crude protein content of the grass were not affected by burning. Burning, regardless of date, resulted in increased soil temperature at 2.5, 5.0, and 10.0‐cm depths. Dry‐matter yields were related to soil temperatures, but the relationship appears to be subject to the modifying influences of rainfall, air temperature, and fertility. It is concluded that judicious burning of Coastal bermudagrass sod is a sound management practice with an added bonus of increased yield in most years. A portable shield for efficient burning of small plots is described.
Response of Several Rice Cultivars to Zn1
Authors: Giordano P. M. , Mortvedt J. J.
Published: July 2010

Differential response to Zn of several plant genotypes other than rice (Oryza sativa L.) has been shown by others. This study was conducted to compare the response to Zn of several foreign and domestic rice cultivars grown under varying fertility and water management conditions in greenhouse pot culture.

Reduction in dry matter yields due to Zn deficiency in the several rice cultivars was in the order: ‘Bluebelle’ > ‘Bluebonnet‐50’ > ‘Dawn’ > ‘Nato’ > ‘Calrose.’ The very early maturing variety Bluebelle was less tolerant to low levels of available Zn than the later maturing cultivars, especially Calrose. Differences existed among cultivars with respect to Zn and P uptake, but could not be related to degree of Zn responsiveness. Adaptation to upland soil conditions differed among cultivars although both growth and Zn uptake were always higher under flooded conditions. The cultivar ‘Sinaloa’ from the Dominican Republic responded well to upland conditions whereas Calrose grew poorly. ‘Juma,’ ‘Bluebelle,’ ‘Starbonnet,’ and ‘Chontalpa’ were intermediate.
Effect of Inoculum Rate on Competitive Nodulation of Glycine max L. Merrill. I. Greenhouse Studies1
Authors: Weaver R. W. , Frederick L. R.
Published: July 2010

To study the competition between inoculated rhizobia and soil rhizobia in forming soybean (Glycine max L. Merr.) nodules, the effect of soil rhizobial population, inoculum strain, and inoculum rate on nodulation of soybeans was determined. Soybeans were grown under greenhouse conditions on 22 soils that contained populations of Rhizobium japonicum ranging from less than 2 to greater than I million/g of soil. Liquid inoculum containing up to 1 billion rhizobia was added to each 2.5 cm of planted row. After 6 weeks of growth, the soybean plants were harvested and the number of nodules, nodule fresh weight, and serotype of rhizobia forming the nodules were determined. Nodule numbers were not increased by inoculation when the soils contained more than 1,000 rhizobia/g of soil. With higher rates of inoculation, the proportion of nodules formed by the inoculum strain was greater. Multiple regression equations indicated that number of cells inoculated and number of soil rhizobia present accounted for 75% of the variation across soils in the percentage of nodules competitively formed by inoculum strains. Soybeans grown on soils containing 1,000 or more rhizobia/g are not likely to be extensively nodulated by inoculum rhizobia applied at normal rates (less than 10,000/seed).
Influence of Soil and Climatic Factors on Fertilizer Response of Wheat Grown on Stubble Land in Southwestern Saskatchewan1
Authors: Read D. W. L. , Warder F. G.
Published: July 2010

In southwestern Saskatchewan moisture and nutrients are frequently limited for wheat (Triticum aestivum L.) grown on stubble land which had produced a crop the previous year. Variations in the severity of limitations between years resulted in wide variations in yield, quality, and response obtained from fertilizer application. Field fertilizer tests were conducted for 4 years to determine the effect of measurable soil and climatic factors on the response of wheat on stubble land to applied N and P fertilizer.

A stepwise multiple regression computer program was used to measure the effect of independent variables on dependent variables when different rates of N and P fertilizers were used. The independent variables were soil moisture and nutrient content at seeding, rainfall during the growing season, and rainfall deficits for half‐month periods during the growing season. The dependent variables were yield, protein and P content of the grain, and net returns.

Each of the independent variables assumed a different degree of importance when compared with different dependent variables. However, certain generalizations are possible.

The NH4‐N form of soil N was responsible for more of the variations than the NO3‐N form. Rainfall during the growing season had a greater influence than stored soil moisture on the yield and protein content of grain grown on unfertilized plots, but the amount of stored soil moisture had greater influence on the effect of fertilizer on the variation in yield and protein content than did summer rainfall. Climatic factors during the growing season were important in causing yearly variations in the unfertilized plots, but the factors that could be measured before seeding had a greater influence on the response to fertilizer.

A knowledge of these variables and of the effect that they have on variations in the response to fertilizer is necessary when planning a fertilizer program.
Triazine Susceptibility of Fall Panicum and Small Crabgrass1
Authors: Harvey R. G. , Doersch R. E.
Published: July 2010

Fall panicum (Panicum dichotomiflorum Michx.) and small crabgrass [Digitaria ischaemum (Schreb.) Muhl.] are becoming increasingly important problems for corn (Zea mays L.) production because of their apparent tolerance to atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine]. It is important to consider other herbicides for the control of these problem weeds and essential to maintain the control of weeds sensitive to atrazine. Consequently, it seems necessary to determine the value of other triazine herbicides for the control of these problem grasses. Experiments were initiated to assess the relative effectiveness of atrazine, cyanazine {2‐[(4‐chloro‐6‐[ethylamino]‐s‐triazine‐2‐methylpropionitrile}, cyprazine [2‐chloro ‐4‐ (cydopropylamino)‐6‐(isopropylamino)‐s‐triazine] and simazine [2‐chloro‐4,6‐bis(ethylamino)‐s‐triazine] for control of fall panicum and small crabgrass in corn when applied alone and in combination. Before greenhouse trials could begin, procedures for breaking dormancy of weed seeds were needed. Germination studies demonstrated that fall panicum seed required prechilling and small crabgrass seed required H2SO4 scarification in order to germinate under laboratory conditions. Greenhouse studies indicated that the order of effectiveness of the herbicides on fall pauicum was cyanazine = simazine> cyprazine>atrazine, and on small crabgrass was cyanazine>simazine>cyprazine>atrazine. Fall panicum was more susceptible to atrazine, cyprazine, and simazine than was small crabgrass, but small crabgrass was more susceptible to cyanazine. Depth of herbicide placement in the soil greatly affected the weed control obtained under greenhouse conditions, suggesting that leaching of the herbicides under field conditions may reduce their effectiveness. Field studies conducted in 1971 and 1972 at two locations tended to verify the greenhouse observations.