bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrogen Production by Selected Astragalus Species1
Authors: Davis A. M.
Published: July 2010

Astragalus species are widely distributed throughout the temperate regions, and are particularly widespread in the northern hemisphere. The genus has a poor image because of a few toxic species (loco weeds) and its contribution to nitrogen fixation and forage production has not been studied.

A greenhouse experiment was conducted to determine the N‐producing capacity of six morphologically diverse Astragalus species: A. asper Jacq., A. cicer L., A. falcatus Lam., A. glycyphyllos L., A. onobrychis L., and A. ponticus Pall., and their effect on the N content of an associated grass, ‘Nordan’ crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schult.]. The highest concentration of N was found in A. ponticus, a robust, nonforage species. Astragalus cicer was second highest. The lowest quantity was found in A. glycyphyllos. Crested wheatgrass had the highest N content when grown in association with A. onobrychis and the lowest when grown with A. falcatus. Residual soil N was highest with A. cicer.

A field study of soil N from 2‐year‐old plants of A. alpinus L., A. cicer, A. galegiformis L., A. glycyphyllos, A. odoratus Lam., and A. scorpurius Bge. resulted in a decreasing N gradient laterally from the center of the plant and with increasing depth. The highest soil N was at the 0 to 15 cm depth and 15 cm from the center of the crown. Each species tested had a different associated soil N level. Astragalus scorpurius had the highest soil N level; A. alpinus had the lowest.

Sufficient variation existed in the N levels associated with native and introduced Astragalus species to warrant further investigation of their N‐fixing characteristics as well as their forage potential.
Leaf Removal to Simulate Grazing of Corn by Lambs1
Authors: Mulkey J. R. , Varner L. W. , Albach E. L. , Drawe H. J.
Published: July 2010

Most of the corn grown in the United States is harvested for grain or silage. Only a small percent is grazed. In corn growing areas where lambs are available, corn might provide some limited grazing without affecting yield. Field experiments (Aridic calciustoll soils) were conducted during 1978–1980 to simulate the grazing of corn by lambs. The lower 2, 4, 6, 8, and 10 leaves were removed at 90 to 100% silking and at 2‐week intervals for 6 weeks thereafter. Removing the bottom 10 leaves either at 90 to 100% silking or 2 weeks afterward caused a significant reduction in grain yield, 1,000‐kernel weight and number of kernels per ha. No significant yield losses were measured with less severe defoliation or defoliation at later stages of maturity.

The data showed that 890 kgha of oven‐dried forage could be removed during the first 4 weeks after 90 to 100% silking or 1,284 kg/ha after 4 weeks from silking without significant yield reductions. At the later stages, protein and P content are below the level required for proper lamb growth.

These studies indicate that yield losses can be minimized by restricting leaf removal during and after pollination. However, before this can become an acceptable practice, additional investigations are needed to study the effects that lambs might have on ears, stalks, and soil compaction.
Deterioration of Alfalfa Swards in the Hot Humid Subtropics of India1
Authors: Bondale Kamalakar , Maiti S. , Chatterjee B. N.
Published: July 2010

Alfalfa (Medicago sativa L.) planted in the humid subtropics of India has not persisted well. To determine the effects of management practices on persistence and production, herbage growth, plant populations, Fusarium incidence on roots, and total available carbohydrates (TAC) were determined.

Seven P and K fertilizer regimes and two cutting frequencies were used with ‘Anand—2’ and ‘Sirsa‐9’ alfalfa cultivars sown in the fall of 1975, 1976,. and 1977 on an Antisol soil in the subtropical plains of the eastern region in India.

In 1976‐1977 and in 1977‐1978, Sirsa—9 yielded 7.6 and 9.7 metric tons/ha, respectively, while Anand—2 produced 6.9 and 8.3 metric tons/ha, of dry matter, respectively. Major fertilizer yield response was almost linear for 0, 22, and 44 kgha of P. Response to K was minimal and only after plant P needs were satisfied. Response to P was greater in 1977‐1978,

Plant populations decreased consistently during the summer to about zero in October 1976 and August 1977, while in 1978 in a better drained area plant populations in July reduced from 70 to 30%.

Root weights decreased drastically from 172 days after sowing (DAS) to 263 DAS regardless of management factor in the first two seasons. Fusarium root rot incidence by 203 DAS was severe for all management treatments except for one K treatment. No relationship between incidence and herbage yield was evident, however. Plant density and disease seventy was positively correlated (r = 0.97). Total available carbohydrate concentrations decreased, also, from about 35 at 172 DAS to 18% at 263 DAS. A positive correlation of r = 0.74 was found between disease severity and TAC.

Additional work is needed to delineate the effects of Fusarium, and soil and plant factors before alfalfa could be recommended as a perennial in the subtropical regions representative of the experimental area.
Effect of Liming on Potato Yields as Related to Soil pH, Al, Mn, and Ca1
Authors: van Lierop W. , Tran T. S. , Banville G. , Morissette S.
Published: July 2010

The objective of this study was to select the most dependable soiltest criterion for determining whether potato (Solanum tuberosum L.) yields might be increased by liming soils. To achieve this end, the crop was grown in unlimed and limed treatments of eight coarsetextured soils (Spodosols), with initial pH values ranging from 4.62 to 5.02 (H2O) and 4.32 to 4.76 (0.01 M CaCl2), in a greenhouse experiment. Liming at 8 g CaCO3/8 liter soil (≃ 2,000 kg/ha) increased the average tuber yield of three soils by 40%. No yield increases were, however, produced by liming soils which had pH values higher than 4.6 (0.01 M CaCl2) or 4.9 (H2O). Extractable soil Al (I N KCl) was as good an indicator as soil pH for predicting crop response to liming. Yields were generally not increased by liming when the concentration of extractable soil Al was < 0.90 meq/100 g. Manganese concentrations in soil or plants were not reliable indicators for predicting the response of this crop to liming. A relationship was found between the concentration of soil Mn extracted with either 1 N NH4OAc or 1 N KCl and the concentration of this element in plant tops (r ≃ 0.75**, significant at the 0.01 level); furthermore, the concentrations of Mn extracted by these solutions were related (r = 0.92**. The Mn content in plant tops also tended to decrease exponentially as soil pH increased (R2 = 47%). Finally, no Ca‐deficiencies were observed on these soils; apparently this crop can absorb sufficient Ca when soils contain as little as about 0.7 meq Ca/100 g (140 µg/g).
Tillage Effects on Soybean Nodulation, N2(C2H4) Fixation, and Seed Yield1
Authors: Lindemann W. C. , Randall G. W. , Ham G. E.
Published: July 2010

Previously, tillage has been shown to affect the yield of soybeans in southern Minnesota. The objective of this study was to determine if different tillage treatments also affected soybean nodulation and N2(C2H4) fixation. Six tillage treatments were sampled in 1975, 1976, and 1977 for nodulation and acetylene reduction activity. The six tillage treatments were part of a 12 tillage treatment experiment established in 1973 under a corn‐soybean rotation system on a Webster clay loam soil (fine‐loamy, mixed, mesic Typic Haplaquoll). Yield was significantly affected by tillage treatment with the yield of the no‐till treatment averaging 22% less than the other five tillage treatments. Few differences were noted in nodule number, nodule weight, or total acetylene reduction activity with respect to tillage treatment. Fall tillage tended to increase nodulation and acetylene reduction over spring tillage, but differences were small. Yield differences due to tillage practice were not attributed to changes in the N2‐fixation system of soybeans.
Seedbed Preparation and Planter Comparisons for Proso Millet Following Wheat1
Authors: Nelson L. A. , Fenster C. R.
Published: July 2010

Advances in herbicides and technology allows producers to replace long‐term (14 month) fallow periods with an additional crop in the semiarid region of western Nebraska. An example of an additional crop is when proso (Panicum miliaceum L.) is planted after winter wheat (Triticum aestivum L.) to give a wheat‐proso‐fallow rotation and allow two crops in 3 years. The purpose of this research was to determine the influence of four methods of preparing a seedbed (burn, plow, stubble mulch, and no till) in combination with three types of planting on yield and agronomic characteristics of proso following wheat. This study was conducted over a 6‐year period (1973–1979) at the High Plains Agric. Laboratory near Sidney, Nebr. on mesic Aridic Argiustoll soil.

The results of this study indicate that neither the seedbed nor planter influenced proso grain yields and test weights, but plant heights, heading dates, and stand counts were influenced by both the seedbed and planter. Generally, no till resulted in lower emergence than burn, plow, and stubble mulch seedbed by 16, 14, and 12%, respectively. Proso planted in the stubble mulch and no‐till seedbeds were 6 and 12% taller, respectively, than proso planted in the burn and plowed plots. Interactions of seedbed, planters, and years influenced yield, test weight, height, heading date, and stand count which suggest that no one system is best under all conditions. The effects of summer rainfall on yield 'and stand count were positively correlated to the rain that fell after planting.
Cotton Boll Period Response to Water Stress and Pink Bollworm1
Authors: Kittock D. L. , Henneberry T. J. , Bariola L. A. , Taylor B. B. , Hofmann W. C.
Published: July 2010

Rapid cotton (Gossypium hirsutum L.) boll development and opening can be beneficial in late season. It can result in increased lint yield, earlier harvest, higher grade, less insecticide use, and reduced storm damage. Research was conducted in the field on a fine loamy, mixed (calcareous), hyperthermic, Anthropic Torrifluvent soil. This study evaluates the effects of water stress in late season (early irrigation termination) and pink bollworm [Pectinophora gossypiella (Saunders)] infestation on time required for cotton bolls to develop from flower to open boll in the field. Water stress speeded boll opening. Bolls from stressed cotton were obtained from field tests with five dates of final irrigation. They opened an average of 17 days earlier than bolls of unstressed cotton in late season. Boll period averages ranged from 41 to 76 days depending upon the degree of water stress and time of year. On droughty (shallow) soil [fine loamy, mixed (calcareous) hyperthermic Anthropic Torrifluvent], water stress effects were significant, but smaller. Delayed boll opening may explain reduced lint yield which at times is associated with late final irrigation. Pink bollworm infested bolls opened about 3 days earlier than non‐infested bolls in two tests with deep soil, but only 0.5 days earlier in a test on droughty soil. Boll period population resembled a normal distribution around the mean until 93% of the bolls were open. For a given day of flowering, 80 % of the bolls (from 10 to 90 %) opened within a 8‐ to 11‐day period.
Edaphic Requirements and Characteristics of Purpletop1
Authors: Boggess Neal , Baker Barton S.
Published: July 2010

Cool‐season forage species are of major importance to the livestock industry in the northeastern part of the United States. Growth of these species is characterized by periods of high production followed by periods of low production. Purpletop [Tridens flavus (L.) Hitchc.], a warm‐season grass species, makes its major growth during the summer months when cool‐season species are unproductive. It may have potential for reducing seasonal variations in forage production when grown in association with cool‐season species. In order to evaluate purpletop for forage purposes, more information is needed on its soil requirements and agronomic characteristics. In this investigation nine indigenous purpletop stands were studied relative to edaphic factors, management, and plant characteristics associated with the stands. A stepwise regression procedure was used to determine soil properties associated with the occurrence of purpletop. The sand fraction in the top 15 cm of the soil profile, as determined by a hydrometer method, was more closely associated with the occurrence of purpletop than any other factor studied. Soil pH, available P, K, Ca, and cation exchange capacity influenced the presence of purpletop in a complex interrelationship. Purpletop was found growing under different pH's, fertilities, and grazing systems, although none of the swards was under intensive management.

Number of leaves (5.7), plant height (114 cm), panicle length (29.2 cm), blade length (40.8 cm), and blade width (12.7 mm) did not vary among sites, suggesting little genetic variation among indigenous populations of purpletop in West Virginia. Forage concentrations of P (0.21%), K (1.44%), Ca (0.22%), and Mg (0.14%) varied among sites but were related to soil levels of these minerals. No obvious problems were found that would suggest poor forage potential. Further investigations are needed to determine its place as a forage in livestock programs.
Effect of Landscape Position and Aspect on Soil Water Recharge1
Authors: Hanna A. Y. , Harlan P. W. , Lewis D. T.
Published: July 2010

The effect of landscape position and slope aspect on soil water recharge under dryland farming was studied in southeast Nebraska. North, south, and east‐facing slopes of Wymore silty clay loam (fine, montmorillonitic, mesic Aquic Argiudoll) were selected. Four positions were identified on each slope, namely, summit, shoulder, backslope, and footslope. Water content of the soil from 0 to 150 cm depth in 30 cm increments were measured weekly by neutron probe for 2 years. Daily precipitation was recorded. Soils of the north‐facing slope were 10 % less efficient in recharge of available water than soils on south‐ and east‐facing slopes during all recharge periods. Soils on footslopes were 6 to 8 % more efficient than other positions throughout the year. Water storage efficiency of the soil appeared to be higher in fall than in spring. Available water recharge was 9 % more efficient during the fall than during the winter‐spring period in all soils regardless of slope aspects and positions. High correlation coefficients (r) existed when soil available water was related to rainfall in either fall or spring recharge period.
Comparison of Bioassays for Atrazine Residue in Soils1
Authors: Brattain R. L. , Fay P. K. , Lockerman R. H.
Published: July 2010

The usefulness of a chemical‐fallow cropping system may often depend on the use of a herbicide bioassay. Several research bioassays have been used to detect phytotoxic soil residues. Some of these bioassays are inexpensive and accurate but are often criticized because of space and time limitations. Four bioassay methods were compared using atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine] treated soil. Nursery cone‐containers filled with atrazine treated soil required little space and provided inexpensive, accurate results when compared to Petri dish assay techniques. Greenhouse pots were as accurate as the conecontainers but were more expensive and required more space. The Chlorella sorokiniana algae bioassay was the least expensive, fastest, and most accurate.
Nitrogen Fixation Capabilities of Plant Introduction Accessions of Pasture and Range Forage Legumes1
Authors: Walsh J. F. , Bezdicek D. F. , Davis A. M. , Hoffman D. L.
Published: July 2010

Many legume species provide excellent quality forage, although the extent to which non‐cultivated species are able to fix N symbiotically is generally unknown. In this report 91 accessions of legumes from the genera Astragalus, Onobrychis, Lupinus, Hedysarum, and Oxytropis were tested for their ability to nodulate and fix N effectively. All accessions were obtained from the USDA Western Regional Plant Introduction Station at Pullman, Wash. Accessions were first screened by evaluating them in small plastic growth tubes. Eighty‐two accessions were nodulated by at least one Rhizobium strain and 53% of the accessions tested were judged to be effectively nodulated based on yield. All accessions that were identified as effective were then grown in Leonard jars and inoculated with single strains of rhizobia. Dry matter yield and nitrogen content were determined for all entries. Twenty‐seven accessions which were tested in Leonard jars were considered to have potential as effective N2‐fixing forage legumes based on comparison with N‐fertilized controls. The highest yielding entries were several A. cicer L. (cicer milkvetch) accessions and a single accession of H. coronarium L. (sulla). This survey has identified a number of accessions of each genus that may have potential for use in forage legume breeding programs.
Soybean Production Systems for Claypan Soils1
Authors: Gebhardt M. R. , Minor H. C.
Published: July 2010

In the Midwestern USA, early planting, narrow‐row spacing, and good weed control are recommended practices for soybean (Glycine max L. Merr.) production. Reduced tillage is being increasingly recommended as a means of reducing fuel use and soil erosion. Little multifactor research has been conducted to define the optimum combination of tillage, planting date, row spacing, and weed control. Two levels of each of these factors were tested in a 24 factorial experiment. Treatment levels for each factor were: planting date (1 May vs. 1 June); row spacing (38 vs. 76 cm); weed control (preemergence herbicides vs preemergence + postemergence herbicides); and seedhed preparation (conventional vs. no‐till). Additional treatment combinations evaluated the effects of mechanical cultivation in wide rows. The study was continued for 5 years on a Mexico silt loam, mainly Udollic and Mollic Ochraqualf soil near Columbia, Mo. Compared to their counterparts, average yield advantages for narrowrow spacing, conventional tillage, June planting, and preemergence + postemergenee weed control were, 5 (not significant), 31, 43, and 51 %, respectively. Lack of yield response of ‘Williams’ soybeans to narrowrow spacing and early planting was attributed to limited rainfall and incomplete weed control. Average weed control was 18, 12, and 31% better with conventional tillage, June planting, and herbicides applied preemergence and postemergence than with their counterparts. Other treatment comparisons showed no difference in soybean yields between bentazon (3‐isopropyl‐1H‐2,1,3‐benzothiadiazin‐4(3H)‐one 2,2‐dioxide) applied postemergence and two timely cultivations. The availability of improved herbicides for selective weed control along with improved planting equipment may lead to an acceptance of continuous no‐tillage for a corn (Zea mays L.)‐soybean rotation. Planting date should be planned so that critical stages of soybean development coincide with periods of probable moisture availability. When mid‐season rainfall is normally deficient, planting soybeans about 1 June may achieve better yields than earlier (1 May) plantings on soils with moisture‐holding characteristics similar to those of the silt loam Udollic and Mollic Ochraqualf soils of central Missouri.
Stockpiling of Three Tropical Forage Grass Species1
Authors: Omaliko C.P.E.
Published: July 2010

During the annual dry season (October to March) in much of the tropics, supply of herbage for the livestock is limited. Hay and silage making are usual methods of conserving herbage but these methods are capital intensive and easily out of reach of the tropical pastoralist. Therefore, other methods of conserving herbage have to be evolved. In this study, stockpiling was used to conserve herbage. The main. objective of the experiment was to study the effects of four stockpiling periods on dry matter yields. Also, residual effects of management on the sward's productivity were assessed. Three forage species that are extensively used in grassland agriculture in southern Nigeria were stockpiled in 1977 and 1978 to provide dry‐season feed. The species were stargrass (Cynodon nlemfuënsis Vanderyst), elephant grass (Pennisetum purpureum Schumach.) and guineagrass (Panicum maximum Jacq). The four stockpiling periods were from either June, July, August, or September to November of each of the 2 years. Yield and quality of herbage from the poststockpiling cuts were estimated in December 1977, February and December 1978, and February 1979. On 15 May 1978 and 1979 residual effects of both the stockpiling and the subsequent post‐stockpiling dry season cuts on the swards performance were assessed. For the 2 year period, dry matter yields averaged over all three species were highest (7,330 kg/ha) and lowest (2,100 kg/ha) from the July and September stockpilings, respectively. The species varied in dry matter yields, and in the stockpiling period that gave the highest yields. Stargrass attained its highest yield from June stockpiling while the other two species were highest from July stockpiling. Elephant grass had a significantly higher dry matter yield (5,500 kg/ha) than either stargrass (4,370 kg/ha) or guineagrass (4,360 kg/ha). Yields from post‐stockpiling herbage cuts in December and February were low (390 to 1,800 kg/ha). However, the quality was relatively high for a herbage at this season—percentage crude protein (CP%) = 4.3 to 10.8; acid detergent fiber (ADF%) = 39.8 to 43.8; and total ash percentage = 4.7 to 12.4. There were no significant residual effects of stockpiling periods on the dry matter yields of herbage harvested early in the following season. These results suggest that stockpiling is an attainable method of providing good quality herbage during the dry season in the tropics. However, more studies involving different aspects of its management will still be required.
Thresher for Immature Soybeans1
Authors: Erbach D. C. , Burris J. S.
Published: July 2010

Some experiments with soybeans [Glycine max (L.) Merr.] require harvest and shelling before complete maturation. A threshing mechanism was developed that orients and breaks the pods of artificially dried soybeans without damaging the seeds. The thresher orients the soybean pods by making use of the pod width‐to‐thickness ratio that is characteristically greater than one. The shelling is done by four wheels. Two wheels grip each pod and the other two crush it. The seeds then can be manually separated from the pieces of crushed pod. The thresher for immature soybeans significantly decreased threshing time when compared with traditional manual methods.
An Interactive Computer Program for Plotting Bar and Line Graphs1
Authors: Hannaway David B. , Fuhrer David , Fribourg Henry A.
Published: July 2010

An interactive computer program has been written for the preparation of bar and line graphs. This program incorporates features present in previously reported programs by other authors, adds additional capabilities and utilizes an interactive rather than batch mode of data entry. Rectangular graphs can be prepared with one or two X axes and one or two Y axes which can be drawn with different scales. Descriptive labeling, statistical designations, arrows, and super‐ and subscripting capabilities are available. Histogram charts have options for groupings of bars, tops on bars, and a choice of hatching types. Line graphs can be drawn in which symbols may be isolated or connected with dots, dashes, or combinations thereof. Mathematical functions defined by the user also may be plotted with the same options for symbol and line types. This program may be displayed on a grpahics terminal for interactive use and instructions given to route for final copy to a drum or flatbed plotter. Final graphs are suitable for publication. This program is written in FORTRAN 77, requires 43 K (4288010 words) to load and run, and presently is operational on a CDC Cyber 170/720.
Magnesium Nutrition and Grain Yield of Maize Having Low Water Potential1
Authors: Aparicho‐Tejo Pedro M. , Boyer John S.
Published: July 2010

Drought decreases plant production but the nutritional status of the plants may alter their susceptibility. Because Mg is a regulatory ion for several aspects of chloroplast photosynthesis, the effect of Mg nutrition on the grain yield of maize (Zea mays L. cv. Dekalb XL43) subjected to a water deficit was examined during most of the grain‐filling period. Plants were grown at two soil Mg levels in a controlled environment capable of providing yields comparable to those in the field. The grain yield, shoot and root dry weight, leaf water potential (Ψw), and tissue mineral composition were determined. Immediately after tasseling, water was withheld from the soil of half the plants until the Ψw had decreased to −1.8 to −2.0 MPa, where it remained until maturity. Low water potentials resulted in a 50% reduction in grain yield and an accelerated leaf senescence. Despite small but significant differences in Mg concentration in roots, stems, and leaves, no differences attributable to differences in Mg nutrition were found in rate of plant dehydration, dry matter accumulation, or grain yield. It is concluded that differences in Mg content of the plant either 1) do not influence response to low − or 2) must be larger than we achieved to see an effect.
Phosphorus Translocation Between Small, Non‐Reproductive Tillers and the Main Plant of Maize1
Authors: Russelle M. P. , Schild J. A. , Olson R. A.
Published: July 2010

Tiller growth and development are generally limited under high plant populations used in modern maize (Zea maysL.) production. The physiological relationship between the main plant and small, barren tillers has not been clarified. Two experiments were conducted to investigate the existence, direction, and relative magnitude of P translocation during different phenological intervals, and to observe the effect of tiller senescence on P translocation. A foliar application of 32P was made at each of three growth stages to the tiller or to the most recently expanded leaf on the main stalk of several maize plants grown hydroponically in the greenhouse. Plants were later separated into tiller, main plant, and roots and were assayed for radioactivity. In a field experiment, foliar applications of 32P were made to tillers of maize grown on a Sharpsburg silty clay loam (Typic Argiudoll, fine, montmorillonitic, mesic) when the main plants were in the 11‐ to 12‐ or 15‐ to 16‐ leaf stage. Aboveground tissue was removed 32 or 33 days after treatment and assayed for radioactivity. Apparent translocation of 32P from main plant to tiller was very small or nonexistent in plants grown in the glasshouse, whereas translocation from tillers to the main plant and roots was substantial. More than 24% of the radioactivity found in the whole plants at sampling had been translocated from the tiller, even though tillers accounted for <0.3% of the total dry weight at the 16‐leaf stage. In the field study, movement of isotope to developing grain from a tagged tiller depended directly on total grain weight and was greater when the tiller did not senesce before sampling. The presence of active, barren tillers may therefore be an important characteristic for reducing maize yield losses where environmental stress limits nutrient absorption and assimilation during late vegetative and early reproductive growth.
Sulfur Accumulation in Tall Fescue, Orchardgrass, and Alfalfa1
Authors: Barney P. E. , Bush L. P. , Leggett J. E.
Published: July 2010

Sulfur nutrition of forages and its utilization by animals are poorly understood. The availability of S to animals apparently is different among forage species. Sulfur accumulation and distribution were examined in seedlings of tall fescue (Festuca arundinaceaSchreb.), orchardgrass (Dacfylis glomerataL.), and alfalfa (Medicago sativaL.). Seedlings were grown in half‐strength Hoagland's No. 1 solution with or without 0.5 mMSO4added to the nutrient solution. When the seedlings were approximately 1 month old, S accumulation kinetic and pH studies were conducted utilizing 35S‐SO4to measure S accumulation in shoots and roots. Sulfur accumulation in plant parts and accumulation rates were higher in those plants previously grown without SO4than in those plants previously grown with SO4. The differences were due to a greater concentration gradient between the nutrient solution and the plant tissue of those plants previously grown without SO4than those grown with SO4. Apparent SO4, absorption sites or carriers were saturated between 0.05 and 0.5 mMSO4. The SO4absorption mechanism of alfalfa appeared to be different than the SO4absorption mechanism of the grasses because increased solution pH decreased S accumulation by alfalfa, but had no effect on S accumulation by the grasses. The ratio of shoot to root S accumulation per unit dry weight during the experimental period was as much as three times greater in tall fescue than in the other species.
Effect of Applied and Residual P on Double‐Cropped Wheat and Soybean under Conservation Tillage Management1
Authors: Sharpe R. R. , Touchton J. T. , Boswell F. C. , Hargrove W. L.
Published: July 2010

In the Piedmont area of Southeastern USA, the economic advantages of double‐cropped wheat (Triticum aestivumL. Thell) and soybean (Glycine maxL. Merr.) have recently resulted in increased acreage of both crops. In many cases, the rotation is wheat and soybean under conservation tillage management. Many soils in this region of the USA are low in P, and it may be advantageous to raise these soils to the high soil test range before initiating conservation tillage practices. The purposes of this study were to determine if it is necessary to raise low P soils to the high soil test range prior to initiating conservation tillage systems and to determine how long a single high rate of P will maintain yields equal to those obtained with annual or biannual applications. Wheat and soybean were double‐cropped under conservation tillage management on a Cecil sandy loam soil (clayey, kaolinitic Typic Hapludult) from 1978 to 1981. The P treatments were applied as a one‐time application in the fall of 1977. Broadcast rates of P were 0,64, 128,256, and 384 kg ha−1. Two annual P applications of 64 kg P ha−1were also included for comparison of residual soil P and annually applied P. One‐time applications of 128 or more kg P ha−1provided sufficient soil P to maintain soybean yields significantly higher than the zero P application rate 4 years after application. The 128 kg P ha−1treatment also produced consistently good wheat yields for 3 years after application, but the 256 and 384 kg P treatments reduced wheat yields in 1978 due to increased lodging and glume blotch ((Septoria nodorum). The data indicate that a single application of 128 kg P ha−1can maintain wheat and soybean yields for at least 3 years in a double‐cropping conservation tillage system without significantly reducing micronutrient uptake. Phosphorus fertilization increased soil P levels and plant tissue P. Applied P increased extractable soil Zn, but decreased the concentration of Zn, Cu, and Mn in the soybean plant tissue.
Effects of Sulfur and Nitrogen Levels and Clipping on Competitive Interference Between Two Annual Grass Species
Authors: Center D. M. , Jones M. B. , Vaughn C. E.
Published: July 2010

Annual ryegrass (Lolium multiflorumLam.) and soft chess (Bromus mollisL.) are often seeded for increased forage production and erosion control on California annual rangelands. Observations in grazed pastures and small plots indicate that the relative proportions of these two species in the community can be influenced by the application of S and N fertilizers. The purpose of this study was to further define the effects of S, N, and clipping on yield response and interference between these two important annual grassland species. Plants were grown in a greenhouse in unleached pots filled with Josephine loam (fine‐loamy, mixed, mesic Typic Haploxerults). Both species were seeded in monoculture and in a 50:50 mixture at a total density of 2000 viable seed m−2. Treatments were factorial combinations of 0, 10, 20, 30, 40, or 80 mg S kg−1soil at the time of planting and N applied at 10 or 30 mg kg−1soil every 14 days. Onehalf of the pots were clipped to a height of 3 cm every 28 days and the other half were clipped only at the termination of the experiment. Dry matter yield and percent S were measured for all clippings and percent N for the last clipping on the repeatedly clipped pots. Only dry matter production was measured on the pots clipped once at the end of the experiment. Yield and response to S and N of ryegrass was greater than that of brome in all treatments. Yield per plant of ryegrass was greater when grown with brome than in monoculture in both the clipped and unclipped pots. In the clipped pots there was little difference in the yield of brome per plant whether grown in mixture or in monoculture, but under unclipped conditions brome yielded more per plant in monoculture than in mixture. Based on analysis of relative yield totals and relative crowding coefficients no significant competitive interference could be detected in the clipped pots at any S or N level. In the unclipped pots the two species were competing and ryegrass was the better competitor. The nature of the interference was not changed with the addition of S or N. From this it was concluded that at the rates used in this study, the major factor influencing competitive interaction between these two species was light, and S and N levels were not major influencing factors.
No‐Tillage of Grain Sorghum on a Shrinking Clay Soil1
Authors: Gerik Thomas J. , Morrison John E.
Published: July 2010

Conservation tillage systems, such as no‐tillage, have shown tremendous potential for controlling erosion, yet results in crop growth and yield have varied with location, environment, and soil type. The objectives of this study were to evaluate the effects of no‐tillage (NT) and conventional tillage (CT) on growth and development of grain sorghum (Sorghum bicolorL. Moench) grown on a heavy clay soil in a humid, subtropical climate. The study was conducted over a 2‐year period on an Austin silty clay (fine‐silty, carbonatic, thermic Entic Haplustolls) with grain sorghum grown in rotation with winter wheat (Triticum aestivumL.). Grain sorghum yields did not differ significantly between NT and CT. Soil water contents were not significantly different between the tillage treatments, but there were consistent trends toward more soil water under NT throughout sorghum development each year. The tillage treatments did not have a major effect on soil temperature. Reductions in the leaf area index at panicle initiation noted under the NT treatment, however, were not reflected in differences in grain yield. Therefore, no‐tillage may become an attractive management alternative for areas with similar soil and climatic conditions.
Soybean Seed Growth. I. Timing of Growth of Individual Seeds1
Authors: Spaeth S. C. , Sinclair T. R.
Published: July 2010

abstract

The seed‐filling duration for whole soybean [Glycine mar (L.) Merr.] plants of indeterminate cultivars is not well defined, because the initiation and termination of rapid dry matter accumulation by individual seeds are sequential, not synchronous. Arbitrary selection of events to delimit duration may not identify durations which are physiologically important. To relate the contribution of individual seeds to whole‐plant seed‐filling duration, the times of initiation and termination of rapid growth were determined for individual seeds at all morphological positions of individual 'Chippewa 64' plants grown under field conditions in Ithaca, N.Y. The soil type was a Hudson silty clay loam (fine, illitic, mesic Glossaquic Hapludalf). Initiation was determined directly by determining the date when the ovule silhouette within intact pods reached a size of 2.5 ✕ 2.0 mm. Termination was defined as the time when cotyledon peripheries changed from green to yellow. Duration of growth of individual seeds was calculated as the time between these two events. Initiation of seed growth progressed sequentially up the stem of plants over periods of more than 21 days in some larger plants. Morphological characteristics other than node number influenced the time of initiation slightly. Seeds on secondary racemes initiated rapid growth 6 to 9 days later than seeds at the same nodes which were located on primary racemes. Seeds ceased growth in a pattern similar to that of initiation but over shorter periods. The long periods for initiation indicate that arbitrarily selected single events are less likely to identify physiologically well‐defined measures of seed‐filling duration.
An Improved Screen‐Cage Design for Use in Plant and Insect Research1
Authors: Lambert Lavone
Published: July 2010

Large screened cages are often necessary for certain types of plant and insect research. Traditionally, the cage frames have been constructed of wood and covered with wire and plastic screen. These cages are very expensive to construct and maintain. To reduce the cost of doing research in screened cages and to improve their serviceability, a 614.4 m2metal frame, screen‐covered cage for inclusion and exclusion of insects was developed. This cage should be of interest to plant breeders and entomologists who work in areas such as host plant resistance to insects, biological control, insect population dynamics, and controlled pollination. The cage is 2.4 m high × 19.2 m wide × 32.0 m long and cost $5450 (1982 prices) including all labor. Cage construction costs spread over the usable life of the cage frame are estimated to be only 44% of those for a wood frame cage. In addition, maintenance costs of the metal frame cage are: only a fraction of those for a wood frame cage.
Quality Changes of Late Summer and Autumn Produced Alfalfa and Red Clover1
Authors: Collins Michael , Taylor T. H.
Published: July 2010

Late summer and autumn produced cool‐season grasses have been widely studied as stockpiled forage for pasturage in late autumn and winter. Knowledge of changes in chemical composition and quality of forage legumes during autumn and winter, however, is lacking. The object of this field study was to investigate the quality and chemical composition of late‐summer and autumn produced alfalfa (Medicago sativaL.) and red clover (Trifolium pratenseL.) forage. Samples of alfalfa and red clover grown on a silt loam soil (Typic Paleudalfs) were collected during autumn and early winter of 2 years following cutting at two times in late summer (average dates of 22 August and 8 September). Quality analysis included in vitro dry matter disappearance (IVDMD), N, P, K, Ca, and Mg concentrations in the forage. Nitrogen concentration in red clover forage declined initially after frost and then increased or remained unchanged during the remainder of the sampling period. The decrease in alfalfa N concentration continued throughout the sampling period in 1975 but was similar to the trend for red clover in 1976. The lowest N concentration recorded for either species was equivalent to 17.8 and 17.2% crude protein (CP) for alfalfa and red clover, respectively. In 1975, forage IVDMD declined continuously after frost and reached a minimum of 56.5% for alfalfa and 51.2% for red clover. In 1976, alfalfa IVDMD increased slightly until approximately 30 days after frost and then declined rapidly through 56 days after frost (12 December). The trend of red clover IVDMD in 1976 was similar to that of alfalfa except that the decline in IVDMD began sooner after frost for red clover. In 1976, the lowest IVDMD measured was 68.3 and 58.9% for alfalfa and red clover, respectively. Concentrations of all minerals studied declined during autumn, K being lost most rapidly, P and Mg intermediate, and Ca least rapidly. Averaged over treatments, the loss in K during the sampling period amounted to 77 and 65% of the K present initially compared with losses of 21 and 15% of the Ca during 1975 and 1976, respectively. Results of a 2‐year field study indicate that IVDMD of both alfalfa and red clover declined substantially during late autumn. Nitrogen concentration in the forage, on the other hand, declined initially after frost but then changed little for the remainder of the sampling period. The concentrations of P and Mg in the forage declined to levels below those suggested for several classes of livestock by the end of the sampling period.
Forage Legume Response to Dicamba and 2,4‐D Applications1
Authors: Griffin J. L. , Watson V. H. , Knight W. E. , Cole A. W.
Published: July 2010

Weed control options in pastures containing legumes are limited due to herbicide selectivity. A field study was conducted for 2 years in northeast Mississippi on a Leeper fine sandy loam (fine, montmorillonitic, nonacid, thermic Vertic Haplaquept) soil to evaluate tolerance of subterranean (Trifolium subterraneumL.), white (T. repensL.), crimson (T. incarnatumL.), red (T. pratenseL.), and arrowleaf (T. vesiculosumSavi) clovers and vetch (Vicia sativaL.) to dicamba (3,6‐dichloro‐o‐anisic acid), 2,4‐D [(2,4‐dichlorophenoxy) acetic acid], and a 3:l (W:W) mixture of 2,4‐D + dicamba. Stands of all clover species were generally reduced where dicamba at 0.56 kg ha−1and where 2,4‐D + dicamba at 0.42 + 0.14 or 0.84 + 0.28 kg ha−1were applied. Forty‐five days after herbicide application legume yields, with the exception of crimson clover, were reduced at least 24% when treated with dicamba. Yields of all clover species were severely reduced where 2,4‐D + dicamba was applied ranging from 50% for subterranean to 84% for red clover. Subterranean clover yield was not affected and white clover yield was only slightly reduced (28%) where 2,4‐D at 1.12 kg ha−1was applied; yields of other clover species were markedly reduced. Vetch was killed with all herbicides applied. To determine residual activity, bermudagrass [Cynodon dactylon(L.) Pers.] sod was treated with dicamba and 2,4‐D + dicamba 120, 90, 60, 30, and 15 days prior to overseeding crimson and white clover on 1 October. The study was conducted for 2 years on a Leeper fine sandy loam soil. Application time of dicamba at 0.28 kg ha‐1and 2,4‐D + dicamba at 0.42 + 0.14 kg ha−1did not affect crimson or white clover yields measured in mid‐May. However, crimson and white clover yields were reduced an average of 39 and 55% where dicamba was applied at 0.56 and 1.12 kg ha−1, respectively, and 37% when 2,4‐D + dicamba was applied at 1.68 + 0.56 kg ha−115 days prior to overseeding compared to 30 days. Selective broadleaf control can be obtained by using 2,4‐D at 1.12 kg ha−1in pastures containing subterranean and white clover. Dicamba at 0.56 kg ha−1or 2,4‐D + dicamba at 1.68 + 0.56 kg ha−1should be applied to warm‐season grass pasture at least 30 days prior to overseeding in order to avoid residual activity on overseeded legumes.
Predicting Cold Tolerance in Perennial Ryegrass from Subcrown Internode Length1
Authors: Wood G. M. , Cohen R. P.
Published: July 2010

The high value of perennial ryegrass (Lolium perenne L.) for turf and forage is unquestioned; however little use is now made of the species in northeastern United States because of its reputed low cold tolerance. Many new cultivars now available have been selected for increased cold tolerance but remain unproven. This research reports a cold hardiness screening test that can aid in extending the usable range of the species northward. A significant negative correlation was found between subcrown internode length in laboratory−germinated perennial ryegrass seedlings and winter survival of the same cultivars grown in the field (Typic Udipsamments soil). Cultivars with a relatively short subcrown internode length generally had less winter injury than did those with a longer subcrown internode length. A period of only 7 days from seed was required to produce the seedlings for internode measurements. Winter survival data used for correlation with the laboratory test were obtained from 1.2 × 1.8 m replicated field plots for the years 1975 to 1977 and 1980 to 1981. We concluded that the technique could be a valuable supplement to other cold tolerance screening methods.
Skip‐Row Planting and Row Pattern Effects on Virginia‐Type Peanut Cultivars1
Authors: Mozingo R. W.
Published: July 2010

Since increasing peanut (Arachis hypogaea L.) production per area of land is a constant goal of researchers, skip‐row planting was an avenue that needed exploring. A 3‐year study was conducted at the Tidewater Research and Continuing Education Center in Suffolk, Va. to determine the effects of two planting patterns, two row patterns, and two cultivars on the yield, value, and grade characteristics of virginia‐type peanut. Planting patterns of solid (all rows planted) and skip‐row (two 0.91 m rows planted and one 0.91 m wide row fallow) were used in a 2 × 2 × 2 factorial arrangement with row patterns of a single row centered in a 0.91 m wide row and twinrows (0.18 m apart) centered in a 0.91 m wide row for the cvs. Florigiant and NC 7. Plots were 3.66 m wide and 10.67 m long with the two center rows harvested for the single row planting and the four center rows harvested for the twin row planting. Soil types for the study were Dragston fine sandy loam (coarse‐loamy, mixed, thermic, Aerie Ochraquults) in 1979, Dragston loamy fine sand in 1980, and an Eunola loamy fine sand (fine‐loamy, siliceous, thermic Aquic Hapludults) in 1981. NC 7 produced a higher percentage of extra large kernels (ELK), sound mature kernels (SMK), total meat (TM) and had a higher dollar value ha−1 than Florigiant. No differences were found between the two cultivars for yield or percentage of fancy size pods (FP). The two row patterns had no effect on yield, value or any grade characteristic. Skip‐row planting produced a significantly (P < 0.01) higher yield and value on a planted hectare basis than did solid planting, while no differences were recorded for any grade characteristic. The highest yield (4599 kg ha−1) and value (2266 dol ha−1) were recorded for NC7 in the twin‐row pattern with skip‐row planting.
Cowpea Response to N Form, Rate, and Timing of Application1
Authors: Beverly R. B. , Jarrell W. M.
Published: July 2010

Cowpeas [Vigna unguiculata (L.) walp.] grown in California may receive little or no N fertilizer, or as much as 100 kg ha−1 N, usually applied preplant. Research was undertaken to determine whether N management could increase seed yield of furrow‐irrigated cowpeas on a fine‐loamy, mixed, thermic Haplic Durixeralf soil. Treatments included no N fertilizer, 168 kg ha−1 N as ammonium nitrate broadcast preplant, and side‐dressing with two N sources [calcium nitrate or urea‐ammonium nitrate (UAN) solutions] at two rates (56 or 168 kg ha−1 N) applied either at bloom or during podfill. Nitrogen application increased seed yield, with side‐dress application being more effective than preplant fertilization. Side‐dress application at bloom increased yield relative to application during podfill, and UAN produced higher yields than calcium nitrate. The higher rate of side‐dress N did not significantly increase seed yield. Preplant fertilization increased vegetative growth, but shoot dry matter differences disappeared during the reproductive period. Symbiotic N2 fixation decreased and mineral N uptake increased (as indicated by ureide‐N and NO−3 −N concentrations in xylem exudate, respectively) in response to N fertilization. Differences between preplant‐fertilized and control plants for these parameters did not persist through reproductive growth, whereas side‐dress application did cause differences during podfill. The increase in seed yield due to N management did not appear to be explained by increased growth, N accumulation in plant parts, or N supply during podfill. We propose that seed yield increased due to decreased consumption of photosynthates by nodules following inactivation of N2 fixation by N fertilization.