bluuebunny/crossref_metadata_2025 huggingface dataset:
Diurnal Variation in Alfalfa (Medicago sativa L.) Dry Matter Yield and Overnight Losses in Harvested Alfalfa Forage1
Authors: Knapp W. R. , Holt D. A. , Lechtenberg V. L. , Vough L. R.
Published: July 2010

Research reported here was designed (a) to study diurnal variation in dry matter yield and nonstructural carbohydrate percentages in alfalfa (Medicago sativa L.) and (b) to compare overnight dry matter and carbohydrate changes in alfalfa cut and left in the field with the changes in standing alfalfa.

First‐ and second‐growth alfalfa were harvested at 7 AM and 7 PM over three 3‐day periods. Each evening, additional alfalfa samples were cut and left overnight in the field so that overnight dry matter and carbohydrate changes in cut and uncut alfalfa could be compared.

Dry matter yields were measured, and freeze‐dried, ground samples were analyzed for carbohydrates. Sucrose and reducing sugars were extracted with ethanol. Starch in the remaining residue was hydrolyzed with amyloglucosidase. The carbohydrates in the extracts were quantitatively assayed using ferricyanide, resorcinol, and phenol‐sulfuric acid procedures.

Dry matter yields, as well as starch and sucrose concentrations, were significantly higher in the evening than the following morning. Glucose and fructose percentages did not change from evening to morning. Through the day, dry matter increased by 5 to 12%, but half or more of this increase disappeared during the night. Standing alfalfa lost 5.5% of its dry matter overnight, while cut forage lost 7.2% overnight in May and 11.0% in July. Dry matter losses in the cut forage were closely related to night temperature, with greatest losses occurring on warmest nights. Cut forage, however, retained higher starch, sucrose, and fructose concentrations through the night than the standing crop. Seventy percent of the night loss of dry matter in standing alfalfa was nonstructural carbohydrate, but only 20% of the loss in cut material was carbohydrate.
Inbred Maize Performance Following Tassel and Leaf Removal1
Authors: Hunter R. B. , Mortimore C. G. , Kannenberg L. W.
Published: July 2010

Mechanical detasseling in hybrid seed production fields of corn (Zea mays L.) frequently is accompanied by loss of some leaf material. Little is known about the effect of this practice on seed production in those instances where the seed parent is an inbred line. We investigated the effects of tassel removal and tassel plus leaf removal on 5 short season inbred lines grown at Guelph, Ontario and 5 later maturing lines grown at Harrow, Ontario. Treatments at both locations consisted of a check, and the removal just prior to anthesis of the tassel, tassel plus one leaf, tassel plus two leaves, and tassel plus three leaves. When tassels alone were removed, there was an average increase “of 6.9%g rain yield. When 1, 2, and 3 leaves were removed with the tassel, yield reductions for the 10 inbreds averaged 1.5, 4.9, and 13.5% relative to the yield for tassel removal only. Yield differences were the result of a reduction in both kernel weight and number of kernels per row. However, yield responses to leaf removal varied greatly between inbreds, and therefore, it is impossible to generalize on the effects on grain yield of leaf removal during detasseling. For some inbreds, particularly shorter season ones, the reduction in yield due to removal of 2 and 3 leaves with the tassel is large enough to warrant consideration in seed production. On the other hand, yield of some of the later inbreds was reduced only slightly when 3 leaves were removed with the tassel. This probably reflects the higher percentages of leaf area removed in earlier inbreds as compared to the later inbreds.
Soybean Yields with Direct and Residual Nitrogen Fertilization1
Authors: Welch L. F. , Boone L. V. , Chambliss C. G. , Christiansen A. T. , Mulvaney D. L. , Oldham M. G. , Pendleton J. W.
Published: July 2010

The objective of this research was to determine the effect on soybean (Glycine max (L.) Merrill) yields of N added at different rates by different times and methods of application, as direct and residual, and as inorganic and organic sources. A number of studies were conducted over a period of several years at 10 field locations in Illinois.

Nitrogen at rates up to 360 kg/ha added for corn (Zea mays L.) the preceding year had no effect on soybean yields. Neither were soybean yields increased by organic sources of N such as manure or alfalfa (Medicago sativa L.), or by combinations of organic and inorganic sources.

Fertilizer N added for soybean as plow‐down, disked‐in, and side‐dressed at early flowering and at pod filling did not increase yields. Nitrogen added for soybeans planted on four dates did not increase yields. High rates of N (1800 and 1440 kg/ha), broadcast and disked‐in in the spring, decreased yield due to germination and seedling injury. Considering all the studies, yields were significantly increased in only 3 out of 133 instances and these occurred at high, uneconomical rates of N fertilizer.

It is concluded that N available to the plant is not the growth factor that presently limits soybean yields in Illinois.
Carbon Dioxide and the Photosynthesis of Field Crops. A Tracer Examination of Turbulent Transfer Theory1
Authors: Harper L. A. , Box J. E. , Baker D. N. , Hesketh J. D.
Published: July 2010

Carbon dioxide was released at ground level in a cotton (Gossypium hirsutum L.) field, and the flux above the crop was measured. The aerodynamic and energy balance methods of calculating carbon dioxide flux underestimated the measured flux by approximately the same amounts. There was considerable variability in the difference between measured and calculated fluxes, and little correlation with meteorological parameters could be found. Differences between measured and calculated fluxes were slightly less with wind orientation across the rows than with orientation parallel to the rows.
Leaching Losses of Sulfur During Winter Months When Applied as Gypsum, Elemental S or Prilled S1
Authors: Rhue R. D. , Kamprath E. J.
Published: July 2010

Sandy soils of the southeastern United States are often deficient in sulfur. The use of sulfate‐containing fertilizers does not result in any buildup of sulfur in sandy soils since the sulfate is readily leached during winter months. Interest, therefore, has developed in the use of elemental sulfur as a means of maintaining an adequate supply of sulfur where leaching is a problem. Studies were conducted with gypsum, finely divided elemental sulfur, and prilled sulfur on a Wagram loamy sand and a Georgeville silty clay loam to determine the levels of sulfate sulfur resulting from additions of these sources. Sulfate contents of the 0 to 15‐, 15 to 30‐ and 30 to 45‐cm depths were determined at various times over a period of 200 days after the different sulfur sources were applied in October.

Almost all of the sulfate, that added as gypsum and that resulting from the oxidation of elemental sulfur, had been leached from the top 45 cm of the Wagram soil 180 days after application. There was essentially no movement of sulfate, however, in the Georgeville soil.

Oxidization of finely divided elemental sulfur appeared to be completed in both soils 200 days after application. There was a buildup of sulfate in the Georgeville surface soil from oxidation of the elemental sulfur. In the Wagram soil, however, leaching was rapid enough to prevent buildup of sulfate in the surface soil. Very little oxidation of prilled sulfur appeared to be occurring to any extent in either soil.
Effect of Soil Moisture During Early Stages of Development on Growth and Yield of Cotton Plants1
Authors: Marani A. , Levi D.
Published: July 2010

The effect of three irrigation treatments on the vegetative development of two cultivars of upland cotton (Gossypium hirsutum L.) was studied in two experiments conducted under different climatic conditions. The treatments differed until the middle of flowering and were designated as L (no irrigation), M (regular), and H (early and excessive irrigation). From mid‐flowering onwards all plots were irrigated regularly.

In both experiments, treatment L resulted in a slower growth rate, smaller plants, fewer nodes and fruiting branches, and smaller leaf area index (LAI), and dry matter (DM) weight throughout the season. Small differences were found between the effects of treatments M and H. No excessive vegetative development was observed in this study. The highest rates of DM production were associated with LAI values between 2.0 and 3.0.

A close relationship was found between, lint yield, DM production and leaf area duration (LAD). Only small increases in lint yield were associated with LAD and DM exceeding values of 100 days and 600 g/m2, respectively, at the end of the main flowering period. Smaller values of LAD and DM, however, were associated with reduced lint yield. Vegetative development was slower under the high temperatures prevailing in the Bet‐She'an valley than in the Coastal Plain area. Lint yield produced from the first cycle of flowering was lower in Bet‐She'an than in the Coastal Plain, but additional yields were produced in Bet‐She'an from the second cycle of flowering.
Effects of Continuous Corn (Zea mays L.), Manuring, and Nitrogen Fertilization on Yield and Protein Content of the Grain and on the Soil Nitrogen Content1
Authors: Anderson F. N. , Peterson G. A.
Published: July 2010

Continuous corn (Zea mays L.) was produced from 1912 to 1972 on an irrigated soil of the Typic Haplustoll group in western Nebraska. Corn yields declined rapidly from 1912 to 1922 when no manure or N fertilizer was used. Annual applications of manure on one‐half of the plot area beginning in 1941 increased yields linearly until 1953. Nitrogen fertilization beginning in 1953 increased corn yields 4685 kg/ha above the control during the first year of application on the nonmanured treatment. Maximum yields have been reached with a combination of manure and N fertilization. Total soil N data indicate that manuring from 1941 to 1972 has returned the soil N level to about 90% of the level that was present in the uncultivated soil in 1912.
Sainfoin‐Birdsfoot Trefoil Mixtures for Pasture, Hay‐pasture, and Hay‐stockpile Management Regimes1
Authors: Cooper C. S.
Published: July 2010

Two nonbloating legumes, sainfoin (Onobrychis viclae folia Scop) and birdsfoot trefoil (Lotus corniculatus L.), were evaluated in pure stands and in mixtures for use in pasture, hay‐pasture, and hay‐stockpile management regimes. Both species, seeded in pure stands or in mixtures, yielded more forage in a hay‐stockpiling management regime than in a pasture or hay‐pasture management regime. In the year of establishment, ‘Remont,’ a twocut‐type sainfoin cultivar, contributed significantly more to yield than ‘Eski,’ a one‐cut‐type sainfoin cultivar, and both sainfoins and sainfoin‐birdsfoot trefoil mixtures yielded more than birdsfoot trefoil alone. Over the 4‐year study period, Remont yielded more than Eski under pasture management, the same as Eski under hay‐pasture management, and much less than Eski under the haystockpile management. Under the hay‐pasture management regime, Eski yielded more than Remont at the hay harvest, but less at subsequent pasture harvests. Under the hay‐stockpile management regime, Eski contributed much more to yield than Remont at the hay harvest, but yields were equal at the late‐September stockpile harvest. Eski was more compatible with birdsfoot trefoil under the hay‐stockpile management system, and produced a higher quality forage at the late‐September harvest. Stand persistence and vigor of both sainfoins under the haystockpile management system were better than under other systems.
Effect of Establishment Method, Variety , and Seeding Rate on the Production and Quality of Alfalfa Under Dryland and Irrigation1
Authors: Hansen L. H. , Krueger C. R.
Published: July 2010

Establishment of alfalfa (Medicago sativa L.) with small grain companion crop is not always satisfactory. This study was designed to compare alternative establishment methods and determine the influence of alfalfa varieties and seeding rates on dry matter and crude protein production and herbage quality. The relationship between alfalfa plant density and root+crown weight and their effect on forage yield were evaluated.

Pure stands of alfalfa were established by four methods: 1) no herbicide or companion crop (check); 2) a plant herbicide, S‐ethyl dipropylthiocarbamate (EPTC); 3) a companion crop of oats (Arena sativa L.) harvested for forage; and 4) a companion crop of oats harvested for grain. Three alfalfa varieties were evaluated: T3X‐8 hybrid, ‘Saranac,’ and ‘Vernal.’ Four alfalfa seeding rates were compared: 4.5, 9.0, 13.5, and 17.9 kg/ha of purelive‐seed (PLS). Studies were conducted at three locations in South Dakota. Experiments at Gayville and Norbeck were under dryland conditions and at Brookings under irrigation.

Alfalfa established with oats harvested for forage yielded the most weed‐free forage dry matter during the seeding year. This was followed in descending order by the yields of alfalfa established with EPTC, the check, and oats harvested for grain. Herbage crude protein yields were similar during the seeding year regardless of establishment method, except for the oat grain treatment which was lower. Second‐year alfalfa dry matter and protein production were not affected by establishment method.

Dry matter yields were higher for Saranac and T3X‐8 hybrid alfalfa than for Vernal when moisture was optimum and winter injury did not occur. Under dryland, there were no differences in yield among the three varieties. T3X‐8 was generally lowest in crude protein content; Vernal was highest in protein late in the season.

With irrigation, higher dry matter and crude protein yields were obtained during the seeding year at each increase in seeding rate. Under dryland, no differences in yield were noted above the 13.5 kg/ha rate during the seeding year. Second‐year alfalfa yield~ increased at seeding rates up to 9.0 kg/ha of PLS at Gayville and Brookings, and up to 13.5 kg/ha at Norbeck. Generally, herbage crude protein content was not affected by seeding rate. Root+crown weights of alfalfa decreased as seeding rates increased up to 13.5 kg/ha.
Accumulation of Dry Matter and Nitrogen Content of Burley Tobacco Growing in Fertilizer‐induced Acid Soil1
Authors: Sims J. L. , Atkinson W. O.
Published: July 2010

Nicotiana tabarum L. cv. ‘Burley 21’ was grown in the field to determine the influence of rate of N fertilization on accumulation of dry matter and certain nitrogenous constituents during the growing season. Nitrogenous compounds in tobacco are presently of interest from a human health standpoint and the chemical constituents of tobacco leaves are known to be associated with dry matter accumulation.

Accumulation of dry matter, protein N, and total N in plants treated with high rates of N fertilizer (up to 450 kg N/ha) was slower than in plants not fertilized or those fertilized with low rates of N during the early part of the growing season. The reduced rates of accumulation were particularly evident until near the flowering stage of growth (70 to 77 days). Thereafter, accumulation plants treated with high rates of N equalled or exceeded that in plants treated with low rates. Weight of dry matter and all measured constituents were greatest in high N treatments at harvest; however, N fertilizer delayed maturity 1 to 2 weeks.

Exchangeable Mn in soil and concentration of Mn in leaves near 40 days increased as N fertilizer level increased. Values for Mn were lower than the literature would suggest as likely to produce toxicity in plants. Thus, factors in addition to Mn toxicity must be considered to explain the observed reduction of early growth by N fertilizers.
Effect of Narrow Trenching in Harlingen Clay Soil on Plant Growth, Rooting Depth, and Salinity1
Authors: Heilman M. D. , Gonzalez C. L.
Published: July 2010

Narrow, backfilled trenches (61 and 102 cm deep) were tested in a Harlingen clay soil as a management technique to increase rooting depth and volume of soil available to roots. Cotton (Gossypium hirsutum L.) was planted directly over the trenches each year for 3 years. Cotton yields were significantly increased by trenching during 1971 and 1972. Yields of 815, 995, 1163, and 1018 kg/ha were obtained during 1972 for check, 61‐cm trench soil‐backfilled, 61‐cm trench, soil‐vermiculite backfilled, and 102‐cm trench soil‐backfilled, respectively. Root penetration and distribution was increased from 60 cm for conventional tillage to 122 cm for 102‐cm deep trenches. An average of 83% of roots for conventional tillage were in surface 30 cm as compared with 43% of 102‐cm trench.

Trenching increased water infiltration rates, decreased soil bulk density in trenches, and increased soil root volume available to plants.

A net reduction in soil salinity occurred for all trench treatments. The greatest reduction was associated with the deepest trench (102 cm). The effects of trenches for decreasing salinity had persisted for 3 years, and it appeared that their effects will persist for several more cropping seasons.
Herbicides, Sprigging Rates, and Nitrogen Treatments for Establishment of Tifway Bermudagrass1
Authors: Johnson B. J.
Published: July 2010

This study was conducted to determine the best system for controlling weeds during the establishment of ‘Tifway’ bermudagrass (Cynodon sp.) without causing injury to the turfgrass. Sprigging rates did not significantly affect the turf ground cover after a 5 to 6‐month growing season. However, for a shorter growing season, the rate of establishment was increased with the higher rate (2.0 vs 0.5 or 1.0 m2/are) of sprigging. Nitrogen (490 g/are) applied at biweekly (eight applications) or monthly (four applications) intervals significantly increased turf ground cover and turf appearance as compared with turf not receiving N. Treatments of dimethyl tetrachloroterephthalate (DCPA) retarded early growth of Tifway bermudagrass. The plants had overcome this growth retardation by 11 weeks following sprigging. Postemergence treatments of monosodium methanearsonate + 2,4‐dichlorophenoxy acetic acid (MSMA + 2,4‐D) were nonphytotoxic to the turfgrass. Sequential treatments of DCPA followed with MSMA + 2,4‐D resulted in excellent season long weed control and the plots had 86% ground cover of turf at the end of the growing season. The turf ground cover was only 36% in plots not treated with any herbicide and 68% in plots treated with DCPA. Repeated postemergence treatments of MSMA + 2,4‐D resulted in good to excellent weed control and these plots had 91 to 96% turfgrass ground cover.
Evaluation of a Thermocouple Hygrometer for Measuring Leaf Water Potential In Situ1
Authors: Campbell Gaylon S. , Campbell Melvin D.
Published: July 2010

Several methods for measuring leaf water potential in situ with thermocouple psychrometers or hygrometers have recently become available. Disadvantages of these methods include difficulty in construction or use, or excessive modification of the leaf environment. Comparisons between in situ and other measurements are generally lacking. We constructed an aluminum hygrometer which is relatively easy to build and use and covers only about 1.5 cm2 of leaf area. This hygrometer was tested in the laboratory and the field and readings were compared with those made with a pressure chamber for several plant species.

The leaf hygrometer worked well in both field and laboratory situations. Comparisons between readings with the leaf hygrometer and a pressure chamber gave regression lines with slopes of 1, but the average pressure chamber reading was 0.4 to 1 bar lower than that obtained with the leaf hygrometer. The leaf hygrometer appeared to respond to plant water potential changes in less than 30 minutes. The equivalent error due to temperature gradients within the chamber was found to be less than 0.4 bar. Measurement precision with this technique appears to be about 1 bar or better.
Corn Yield as Affected by Fertilization and Tillage System1
Authors: Fink Rodney J. , Wesley Dean
Published: July 2010

Recent adoption of no‐tillage planting systems by many farmers has raised questions concerning comparative yields with conventional tillage systems and problems associated with nutrient absorption. No‐tillage systems generally require surface application of P and K, thus studies are needed to determine whether surface‐applied nutrients can supply plant needs. The objectives of this study were to determine 1) the desirability of applying P and K on the soil surface, 2) comparative yields between zero‐tillage and conventional‐tilled corn (Zea mays L.) production systems, and 3) the movement of P and K into the soil profile.

Two soil types, an Ipava and a Clinton silt loam, were selected for these studies. A completely randomized experimental design with four replications was utilized on each soil type. Soil samples were taken at four depths of the soil profile at initiation of the studies and again during the final year. Soils were analyzed for P and K in order to determine the movement of surface applications of these nutrients.

Movement of P and K into the soil profile following surface application on untilled areas was slow with both nutrients—K moved more rapidly than P. Following 2 years without P or K, yield levels were restored on plots receiving one annual application of both nutrients. Average yields of corn were similar on both tillage systems on both soil types.

Yield trials produced similar yields with conventional and with zero‐tillage systems, although some problems occurred with reduced‐tillage systems. Surface application of P and K was a satisfactory method of meeting the plant needs for these nutrients.
Reflectant Induced Modification of Soybean Canopy Radiation Balance. I. Preliminary Tests with a Kaolinite Reflectant1
Authors: Doraiswamy Paul C. , Rosenberg Norman J.
Published: July 2010

‘Amsoy’ soybeans (Glycine max (L.) Merr.) grown at Mead, Nebraska were coated with kaolinite during 1969 and 1970 to test whether reflection of incident solar radiation can be effectively increased in the field. Increased reflection reduces the amount of radiant energy available and hence reduces the quantity of water consumed by transpiration. Total reflection (300 to 3,000 nm) from the coated crop, measured with an inverted pyranometer, was increased by about 8%. Net radiation was decreased by about 8%. Spectral reflection, measured with a spectroradiometer, was increased primarily in the visible range (380 to 750 nm). Treatment induced differences in reflection were minor in the near infra red range (750 to 1,150 or 1,550 nm). Treatment caused some redistribution of light onto the lower canopy. Results of this preliminary study indicate that the radiation balance of field grown soybeans can be altered by application of reflectant materials.
Variability of Sugar Content in Seed of Glycine max (L.) Merrill and G. soja Sieb. and Zucc.1
Authors: Hymowitz T. , Collins F. I.
Published: July 2010

The flatus‐producing factor in soybean [Glycine max (L.) Merrill] seed appears to be associated with the sugars raffinose and stachyose. The objective of this investigation was to measure the variability of total sugar and individual sugars in seed from soybean cultivars, the soybean genetic type collection, plant introductions of G. max that were formerly known as G. gracilis Skvortz., and plant introductions of G. soja Sieb. and Zucc.

Among the cultivars, ‘Bansei’ had the highest total sugar, sucrose, and stachyose contents—16.6, 10.2, and 3.8 g/100 g seed, respectively. Seed of ‘Sioux’ had the lowest total sugar and sucrose contents—6.2 and 3.0 g/100 g seed. Seed of ‘Chippewa’ and ‘Norsoy’ had the highest and lowest fructose contents—2.1 and 0.4 g/100 g seed, respectively. Raffinose content was highest in seed of ‘Cayuga’ and lowest in ‘Hidatsa’ and Sioux. Strains T‐223 and T‐218 in the genetic type collection had very high stachyose contents—5.8 and 4.8 g/100 g seed. In seed of G. soja PI 203.246, the stachyose content was only 0.6 g/100 g seed.

The extent of variability detected for total sugar and individual sugar content offers opportunities for modification of the sugar components in soybeans.
Leaching and Uptake of Nitrogen Applied to Annual Grass and Clover‐Grass Mixtures in Lysimeters1
Authors: Jones M. B. , Street J. E. , Williams W. A.
Published: July 2010

The annual grassland soils of California are nearly always N deficient. If early winter feed is desired and total production is to be increased, N must be added, either by a legume or through N fertilization. Comparison of these two N sources in terms of forage and protein production and groundwater pollution is important for efficient management of land, water, and N resources.

This study was initiated to measure the effect of N fertilization on forage yields, N‐uptake by the plants, and N leached from the soil where grass grew alone or from clover‐grass mixtures.

Grass (soft chess, Bromus mollis L.) growing alone, grass plus subclover (Trifolium subterraneum L.), and grass plus rose clover (T. hirtum All.) were grown in lysimeters on Josephine soil with and without N applied in the autumn of each of 4 years.

Nitrogen fertilization increased winter forage yields and N‐uptake in all species mixtures. However, in the spring harvest, clover‐grass mixtures yielded as much forage and N‐uptake without N as with N applied. Apparent recovery of the applied N in the forage was 25% for the grass, −2% for the subclover‐grass, and 0% for the rose clovergrass. The amount of apparent fertilizer N found in drainage water was 37% from grass, 58% from subclover‐grass, and 50% under rose clover‐grass. Without N fertilization the N leached was about the same from clovergrass as from grass alone. Of total N leached, 94% was in the fall, 6% in winter, and less than 1% in spring, whereas the total drainage water was divided 43% in the fall, 54% in whiter, and 3% in spring. With N fertilization, NO3‐N in the water in the fall was 45 ppm from clover‐grass and 38 ppm from grass. Without applied N, the NO3‐N values were 25 ppm in the fall and were 1/10 as great in winter and about 1/100 in spring. There was no rain in the summer.
Smoothing Data with Fourier Transformations1
Authors: Kimball B. A.
Published: July 2010

The natural variability of agronomic data often masks underlying true curves. A relatively new Fourier transform data smoothing technique, when tested on several sets of noisy agronomic data, gave very satisfactory reductions of this variability. The data were smoothed by computing the Fourier transform, setting high frequency noise components of the resulting variance spectrum to zero, and then computing the inverse Fourier transform. The key to the technique's success lies in the fact that the data were dominated by relatively low frequencies of variation which could be separated from the higher frequency noise. This simple, lucid interpretation of the filtering action makes Fourier transform smoothing even more attractive than other methods whose filtering action is not so intuitively obvious. The technique was superior to two other methods in extracting a true curve from noisy artificial data.
Synchronization of Flowering in Corn (Zea mays L.) by Clipping Young Plants1
Authors: Cloninger F. D. , Zuber M. S. , Horrocks R. D.
Published: July 2010

The synchronization of flowering between parents for hybrid seed production is essential for maximum seed yield in corn (Zea mays L.). In this study, the simultaneous flowering of parental rows planted on the same date was attempted by clipping plants near soil level at three stages of growth. Mean delays for the 28 possible single crosses among 8 inbred lines of 5.5, 7.6, and 6.7 days from planting to anthesis and 5.5, 7.7, and 7.1 days from planting to 50% silking were observed for plants clipped at the 4, 6, and 8‐leaf stages of growth, respectively. The range among single crosses in delay of flowering dates was 4.2 to 6.8 days for clippings at the 4‐leaf stage of growth.

Stands were reduced 18, 44, and 25% by clipping at the 4, 6, and 8‐leaf stages, respectively. Yield reductions at these same clipping stages were 11, 38, and 46%. Clipping at the 4‐leaf stage gave the best combination of flowering delay with the least decrease in stand and yield. The combining ability analysis indicated a complex inheritance pattern of factors associated with flowering dates in corn.
Components of Forage Quality in Sericea Lespedeza in Relationship to Strain, Season, and Cutting Treatments1
Authors: Cope W. A. , Burns J. C.
Published: July 2010

A study of forage quality was made on three genetically different strains of sericea [Lespedeza cuneata (Dumont) G. Don]. The study was designed to evaluate forage samples over a wide range of plant maturity, since previous studies have been restricted largely to mature hay samples representing a narrow range. The forage sampling plan covered two distinctly different growth periods, early spring and mid‐summer. The three sericea strains were harvested at weekly intervals for short periods during the spring and summer of 1970 and 1971. Leaf and stem portions were separated and placed in liquid nitrogen in the field. Forage quality was evaluated by in vitro dry matter disappearance (IVDMD), by concentrations of total fiber and fiber components, and by concentration of the anti‐quality component, tannin. Forage quality, as measured by IVDMD, was generally low, especially for leaf samples high in tannin and stem samples from the more mature growth stages. A low‐tannin strain averaged higher in IVDMD than two high‐tannin strains over all harvests. Leaf IVDMD was sharply depressed as tannin values approached 10% and then declined slowly with increasing concentrations. Leaf fiber had little direct effect on IVDMD at high tannin levels. IVDMD of stem samples decreased rapidly with successive harvests in both spring and summer. Fiber content was high at an early growth stage for both spring and summer harvest periods. The correlation of fiber content with IVDMD was high and negative. There were only small strain differences in fiber content. Stem tannin content for the summer harvest in 1971 was high enough to affect IVDMD and interacted with fiber content to give very low values. For stem samples from the first harvest period, simple regression of fiber on IVDMD accounted for a significant proportion of the variation in IVDMD (r2 = 0.81 and 0.84, respectively, for neutral detergent fiber and acid detergent fiber. For the second harvest period, the addition of tannin in multiple regression equations increased the predictability to R2 = 0.95 and 0.94, respectively. Neither the simple nor the multiple regressions accounted for a large proportion of the variation in leaf IVDMD.
Estimating Evapotranspiration Using Canopy Temperatures: Field Evaluation
Authors: Stone L. R. , Horton M. L.
Published: July 2010

Evapotranspiration generally has been estimated on a small scale because of cost and time required for measurements. Thermal scanners provide a possible way of estimating water loss from surfaces by using remotely sensed surface temperatures. In this study, designed to evaluate the feasibility of using canopy temperatures in estimating evapotranspiration (ET), we employed five equations. Sorghum bicolor L (Moench) was used in the field investigation. Three of the equations were the well‐known methods of van Bavel, Penman, and energy budget‐Bowen ratio. The other two use the temperature of the evaporating surface in estimating ET and are referred to as the Bartholic‐Namken‐Wiegand (B‐N‐W) and Brown‐Rosenberg (B‐R) methods. Using simple linear regression and correlation analyses, we found the B‐N‐W estimates to be approximately 17% smaller and the B‐R estimates to be approximately 22% larger than typical estimates obtained by the Penman and energy budget‐Bowen ratio methods. Both methods appear usable in determining ET rates of vegetated surfaces, with the B‐N‐W method requiring less input data than the B‐R method.
Effect of Sulfur Fertilization on the N‐S Ratio in Soybean Varieties1
Authors: Dev G. , Saggar S.
Published: July 2010

Changes in N‐S ratios in 12 varieties of soybean (Glycine max L. Merrill) under varying levels of applied S were studied in a greenhouse experiment. Sulfur application lowered total N‐total S ratios and widened protein N‐protein S ratios. At the S level, where constancy in total N‐total S ratios was obtained, one part of S was required for every 15 parts of N in protein for varieties ‘Hardee,’ ‘Clark,’ ‘Pb. soybean No. 1’; 12 to 14 parts of N for ‘Dare,’ ‘Hampton,’ ‘Hood,’ ‘Semmes,’ ‘Improved Pelican,’ and ‘Bragg;’ and 16 parts of N for ‘Hill,’ ‘Davis,’ and ‘Pickett 71.’
Phosphorus Utilization by Flax, Wheat, Rape, and Buckwheat from a Band or Pellet‐like Application. II. Influence of Reaction Zone Phosphorus Concentration and Soil Phosphorus Supply1
Authors: Strong W. M. , Soper R. J.
Published: July 2010

Two pot experiments have been conducted to study separately the influence of two factors on applied P utilization by four crops: flax (Linum usitatissimum, L., cv. ‘Redwood’), wheat (Triticum vulgare L., cv. ‘Manitou’), rape (Brassica napus L., cv. ‘Tanka’), and buckwheat (Fagopyrum esculentum Moench). These crops vary greatly in their ability to utilize P from band or pelletlike phosphate applications. To Simulate a pellet‐like phosphate application, 32P labelled calcium phosphate was mixed with, and confined to a small fraction of the soil mass. In one experiment the quantity of P recovered from fertilizer reaction zones containing one of three calcium phosphates of widely different solubility products [hydroxyapatite (HA), octacalcium phosphate (OCP), or dicalcium phosphate dihydrate (DCPD)] demonstrated the existence of a direct relationship between reaction zone P concentration and crop recovery of applied P. In the other experiment the amount of P recovered from a reaction zone containing 32P‐labelled DCPD was reduced dramatically when the availability of P in soil external to the reaction zone was increased by mixing calcium phosphate throughout. This finding indicates the existence of an inverse relationship between the availability of soil P and the utilization of P from a band or pellet‐like phosphate application.

Utilization of P from phosphate fertilizer reaction zones by these crops can be explained on the basis of the performance of that portion of the root system which feeds on the applied phosphate, i.e. the proportion of the root system which develops within the fertilizer reaction zone, and the rate at which it absorbs the applied phosphate. The influence of the two factors, reaction zone P concentration‐and soil P availability, appear to affect the utilization of applied P by their control over the performance of the roots within the fertilizer reaction zone.
Irrigation, Row Width, and Plant Population in Relation to Growth Characteristics of Two Soybean Varieties1
Authors: Doss B. D. , Thurlow D. L.
Published: July 2010

Soybean (Glycine max (L.) Merrill) yields in the past have varied considerably from year to year in the southeastern United States. Many factors are important in soybean production, but water stress at critical growth periods appears to be one of the most frequently limiting factors.

Soybeans were grown on a Lucedale fine sandy loam soil to determine the effects of three soil water regimes at two row widths and three plant population levels on water use, rate of plant growth, and bean yield of two varieties.

Water use rates by soybeans were influenced more by soil water regime than by row width or variety. Average rates during the season ranged from 0.05 to 0.84 cm/day, depending on the amount of available water in the soil.

Variety had the greatest influence on plant height. Final plant heights ranged from 10 to 15 cm greater for ‘Bragg’ than for ‘Hampton 266.’ Heights were increased by irrigation and plant population level, but were not affected by row width.

Average bean yields were influenced more by irrigation or variety than by row width or plant population. Average bean yields by soil water regimes were 2,020, 2,420, and 2,490 kg/ha for no irrigation, intermediate, and high irrigation, respectively. Bragg averaged 2,420 kg/ha and Hampton 266 averaged 2,150 kg/ha. Row width and plant population showed little influence on average bean yields.
Phosphate Placement for Corn in Chisel and Moldboard Plowing Systems1
Authors: Cihacek L. J. , Mulvaney D. L. , Olson R. A. , Welch L. F. , Wiese R. A.
Published: July 2010

Field experiments conducted at three locations in Nebraska and one in Illinois compared tillage by chisel and moldboard plowing for corn (Zea mays L.). Specific objectives were to compare the two tillage systems in respect to growth characteristics and final yield of corn, to ascertain the most effective method of applying fertilizer P with chisel plowing, and to determine residual P distribution in the rooting zone after 3 years with the various systems employed.

Fertilizer P was applied at three or four rates as orthophosphoric acid in conjunction with varied tillage and placement as follows: 1) surface broadcasting of P and incorporation by chisel plow tillage, 2) P application by chisel plow at 18 to 20‐cm depth, 3) chisel plow tillage with P banded beside the row at planting, and 4) moldboard plow tillage following surface broadcasting of P. Primary tillage was accomplished in the fall after corn harvest.

Somewhat higher yields were obtained with moldboard plowing than with chisel plowing, irrespective of P rate or placement. This benefit for the moldboard plow is offset by the moisture conservation and erosion control advantages afforded by the chisel. Broadcast P prior to chiselling and deep placement of P with the chisel gave comparable yields, although deep placement afforded greater season‐long crop feeding on the fertilizer. Runoff loss of P on sediment was minimized with chisel placement of the P.
Effect of Plant‐Available Stored Soil Moisture on Corn Yield: II. Variable Climatic Conditions
Authors: Leeper R. A. , Runge E. C. A. , Walker W. M.
Published: July 2010

Agronomists have long been interested in how variation in soils and climate are related to crop yields. An experiment was conducted to quantify the effect of weekly plant available stored soil moisture (PASSM) during 10 weeks of the growing season on corn (Zea mays L.) yield under constant and variable climatic conditions. The objective of this study was to determine how much of the variation in corn yield was due to variations in soils and climate and to develop a model relating corn yield to soil, rainfall, and temperature which could be used to predict corn yields for other locations not studied. Plot yields from four Illinois locations (farms) for 3 years (1969–1971) were correlated with weekly PASSM, rooting depth, or available water holding capacity in the rooting zone and climatic data (rainfall and temperature). Experimental plots had high fertility and management. Weekly PASSM, rainfall, and temperature values were summed by a method similar to Fisher's polynomial technique as previously modified.

Differences in corn yields due to soils, locations, and among years within locations are due to differences in climate (rainfall and temperature) and differences the ability of the soil to supply water. When correlated with rainfall and temperature data PASSM determined on a weekly basis was slightly less efficient (R2 = 0.80) than was rooting depth (R2 = 0.83) or amount of preseason water available in the rooting zone (R2 = 0.81) in explaining variations in corn yield. Equations fitted to the data should be useful models in predicting corn yields for other locations and soil conditions not studied. The model utilizing the amount of preseason water available in the rooting zone is particularly easy to utilize in predicting corn yield for other locations from soils and climatic data.
Effects of Nitrogen, Phosphorus, and Plant Density on Sunflower1
Authors: Zubriski J. C. , Zimmerman D. C.
Published: July 2010

It is generally recognized that appropriate plant density and appropriate fertilizer application to deficient soil are necessary for optimum yield of crops. These variables also affect the quality of some crops. There is limited research data on the effects of these variables on yield and quality factors of oil and confectionery cultivars of sunflower (Helianthus annuus L.) grown in North Dakota. The objectives of this research were to determine the effects of three rates of nitrogen fertilizer, two rates of phosphorus fertilizer, and three plant densities upon seed yield, head size, oil concentration of oil cultivars, and seed size of confectionery cultivars.

Nitrogen fertilizer increased seed yield, head size, oil yield from oil‐type cultivars, and percentage of large size seeds from confectionery cultivars. However, N reduced oil concentration of oil‐type seeds and percentage of medium size seeds of confectionery cultivars. Yield response to nitrogen was obtained at all locations because soil tests for nitrate‐N to a 61 cm soil depth were less than 60 kg/ha at planting time.

Phosporus fertilizer failed to increase seed yields in 10 of 12 trials and had little effect on size of confectionery seeds and oil concentration of oil‐type seeds. Lack of response to phosphorus cannot be explained by soil test data.

Increasing plant density increased seed yield, yield of oil from oil‐type sunflower, and percentage of medium‐size seeds from confectionery cultivars. Increasing plant density reduced head size and percentage of large‐size seeds of confectionery cultivars. Percentage of small sized confectionery seeds was increased by increasing plant density and decreased by increasing rate of nitrogen fertilizer.

Results of this study show that nitrogen and plant density have a relatively large effect on seed yield and a smaller effect on oil concentration and seed size.
Effects of Potassium Topdressing a Low Fertility Silt Loam Soil on Alfalfa Herbage Yields and Composition and on Soil K Values1
Authors: Smith Dale
Published: July 2010

Alfalfa (Medicago sativa L.) uses large amounts of soil K. The purpose of this study was to determine the amount of topdressed K needed to obtain maximum herbage yields from alfalfa under presently recommended harvest schedules. ‘Ranger’ alfalfa was established on a low K Typic Argiudoll (Plano silt loam) and topdressed the first two of three harvest years with zero, 56, 112, 224, 448, 672, 896, and 1120 kg/ha K as KCI. Two annual harvest schedules were used; (a) three cuts at first flower and (b) same as (a) plus an early October cut (4 cuts). Yield responses were similar for the two harvest schedules, but 3‐year average yields were highest with three cuts annually. Residual yields and stands showed that the detrimental effect of an early October cut (4 cuts) was partially alleviated by high K topdressing rates. The 3‐year average yields were highest with 672 kg/ha of topdressed K, and then decreased at higher K rates. Herbage K percentage at 672 kg/ha K averaged 2.8% for the 3 harvest years, and 56% of the fertilizer K was recovered in the herbage. Analysis of total herbage from the third harvest year showed that Mn concentration, as well as K, increased as K topdressing rate increased, whereas concentrations of N, P, S, Ca, Mg, Na, Cu, Zn, and B decreased. There was no effect on IVDDM, Fe, and AI concentrations. It is concluded that higher rates of applied K are needed than presently are being used in order to obtain and maintain high herbage yields and persistence from alfalfa stands.
Effects of Frequency of Sprinkling With Saline Waters Compared With Daily Drip Irrigation1
Authors: Bernstein Leon , Francois L. E.
Published: July 2010

We previously attributed the injury to bell peppers (Capsicum frutescens) by sprinkling them with saline water to flushing into the root zone of salts accumulated at the soil surface rather than to foliar salt absorption. These two possible mechanisms of salt injury have now been studied further by observing the effects of sprinkling frequency and the related degree of surface salt accumulation. Bell peppers in small field plots were sprinkled every 2.3, 3.5, and 4.75 days (average intervals for each treatment) with low‐salt (450 mg/liter) and medium and high‐salt waters (1,000 and 2,000 mg/liter of added NaCl + CaCl2, respectively). Three additional plots were drip irrigated daily with the three waters for comparative purposes. Soil salt distributions, foliar salt contents, and bell pepper yields were determined.

Sprinkling with the low‐salt water and drip irrigation with all three waters caused no leaf damage. Plants sprinkled every 2.3 days with the two saline waters suffered more leaf burn and produced lower yields than plants sprinkled less often. Sprinkling with the medium‐salt water reduced yields appreciably only at the highest frequency (2.3 days) but sprinkling with the high‐salt water reduced yields more than 50% at all sprinkling frequencies, compared to a yield loss of only 14% by drip irrigation with this water. Since sprinkling with the medium‐salt water caused no observable osmotic shock by salt flushing, injury and yield loss appear to be related primarily to foliar salt absorption. Sprinkling with saline waters appears to induce sensitivity to sodium and chloride in bell pepper plants as it does in other species that do not appear sensitive to these ions when surface irrigated.
Response Curves of Various Turfgrasses to Application of Several Controlled‐Release Nitrogen Sources1
Authors: Volk G. M. , Horn G. C.
Published: July 2010

Responses of turfgrasses to controlled‐release N sources, especially the newer materials have not been adequately evaluated under field conditions. This study obtained N time‐release curves as measured by clippings taken periodically after the initial response to readily available N such products contain had subsided. Materials were suface‐applied once, or at widely spaced intervals, to six different turfgrasses. Three to 4‐day growth clippings were taken periodically to assess current N uptake rate against that from a standard treatment consisting of a continuous, uniform, weekly application of NH4NO3. Sulfur‐coated urea (SCU of 9% dissolution rate) gave the most desirable type of response for summer fertilization, followed by isobutylidene diurea (IBDU), activated sewage sludge (Milorganite), and ureaform (UF). The latter two were quite similar in latent response characteristics. IBDU was superior to the other materials for winter usage, because it did not show the cold weather depression of latent N release exhibited by Milorganite, SCU, and UF. It is postulated that an initial slow N‐release rate of IBDU, and the favorable cold weather response curve is the result of the differential effect of temperature on nitritication and, therefore, on acidity and dissolution rate of IBDU in the microenvironment of the pellet. Responses to IBDU of various pellet‐size ranges corroborates that surface dissolution is the N‐release mechanism, and that varying the pellet size is a valuable method for controlling the N‐release rate.