journal article
LitStream Collection
Home
doi: 10.2134/agronj1974.00021962006600010002xpmid: N/A
An understanding of seasonal nutrient accumulation patterns under varying fertility levels is important for planning an efficient fertilization program. Field experiments were conducted to determine the effects of varying rates of N (0, 60, and 120 kg/ha) and P (0 and 26 kg/ha) on the N, P, and K accumulation pattern by various plant parts of a sorghum [Sorghum bicolor (L.) Moench] hybrid. Plant samples were collected at weekly intervals, partitioned into plant parts, and analyzed for N, P, and K.
doi: 10.2134/agronj1974.00021962006600010003xpmid: N/A
The presence of silica (SiO2) has been reported as significantly affecting the nutritional value of forages. This study was conducted to determine the SiO2 concentration in forage samples collected monthly from 2‐ha paddocks of ungrazed tall fescue (Festuca arundinacea Schreb.) and ‘Coastal’ bermudagrass (Cynodon dactylon (L.) Pers.) as they matured, and to determine the monthly SiO2 concentrations of vegetative tall fescue, tall fescue‐‘Ladino’ clover (Trifolium repens L.), orchardgrass (Dactylis glomerata L.), orchardgrass‐Ladino clover, Coastal bermudagrass, and stockpiled tall fescue which were incorporated into four grazing systems. Samples representative of forage grazed by yearling beef heifers were collected monthly from caged areas to determine the SiO2 levels.
Shenk, J. S.; Risius, M. L.; Barnes, R. F.
doi: 10.2134/agronj1974.00021962006600010004xpmid: N/A
Crownvetch (Coronilla varia L.) has been reported to contain antiquality constituents. Feeding trials were conducted to determine the feasibility of using the weanling meadow vole (Microtus pennsylvanicus) as a bioassay to assess the effects of these antiquality constituents on feed intake, body‐weight change, and ration digestibility. The feeding value of crownvetch forage was compared with that of alfalfa (Medicago sativa L.), birdsfoot trefoil (Lotus corniculatus L.), and sainfoin (Onobrychis viciaefolia Scop.) incorporated at 15% dry weight into a nutritionally adequate and balanced diet. Voles had lower intake and lost weight when fed crownvetch than when fed the other legume forages. No relationship existed between intake or weight loss and apparent digestibility. However, not all crownvetch forages resulted in lower intake and weight loss, and samples differed in their capacity to cause adverse vole responses from year to year. Voles also differed in their responses to forage fed from individual plants of the ‘Chemung’ cultivar. Low intake appeared to be the primary reason for the weight loss and death which occurred on many samples. The information presented indicates the presence of an antiquality constituent(s) in crownvetch forage that should be thoroughly investigated for its effects upon other animal species, especially rapidly growing monogastrics.
Al‐Abbas, A. H.; Barr, R.; Hall, J. D.; Crane, F. L.; Baumgardner, M. F.
doi: 10.2134/agronj1974.00021962006600010005xpmid: N/A
Since the advent of spectral mapping and identification of vegetation by remote sensing methods, information about differences in plant nutrient status has gained prominence. Therefore, we decided to study the reflectance, transmittance, and absorptance spectra of “normal” and six types of nutrient‐deficient maize (Zea mays L.) leaves. Nitrogen‐, phosphorus‐, potassium‐, sulfur‐, magnesium‐, and calcium‐deficient leaves were analyzed at 30 selected wavelengths from 500 to 2,600 nm. The analysis of variance showed significant differences in reflectance, transmittance, and absorptance in the visible wavelengths among leaves 3, 4, and 5, among the 7 treatments, and among the interactions of leaf positions and treatments. Only treatments in the infrared wavelengths produced significant differences.
Ashley, D. A.; Elsner, J. E.; Brooks, O. L.; Perry, C. E.
doi: 10.2134/agronj1974.00021962006600010006xpmid: N/A
Seedling cotton (Gossypium hirsutum L.) growth rate is frequently retarded due to adverse environmental conditions and the effects are often reflected in retarded development and performance later in the season. In efforts to find ways of enhancing the ability of the seedling to grow under adverse conditions, cotton plants were grown under field conditions with black plastic mulch, NaNO3, NH4NO3, and (NH4)2SO4 sources of N, and irrigation treatments. Vegetative development, nitrogen uptake, and fruiting behavior were measured in early stages of growth and final yields taken at maturity. Ammonium sources of N resulted in enhanced seedling vigor, plant height, rate of early‐season dry weight accumulation, and rate of early flowering compared to nitrate N sources. A complete ground cover of black plastic mulch gave an additional increase in the early‐season growth and fruiting parameters above that obtained from ammonium N alone. Nitrogen concentration in the tissue in early season did not differ among the treatments; therefore, total N uptake followed closely the response in dry weight accumulation. Yield of cotton was not materially affected by source of N. In general yields were higher from plots receiving NH4NO3 plus plastic mulch than from plots treated with NaNO3 and no plastic mulch.
Campbell, Gaylon S.; Campbell, Melvin D.
doi: 10.2134/agronj1974.00021962006600010007xpmid: N/A
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.
doi: 10.2134/agronj1974.00021962006600010008xpmid: N/A
Susceptibility to winter injury has limited the use of bermudagrass (Cynodon sp.) to a few hardy cultivars in the “upper” South which is an environmental transition area for turfgrass species. An understanding of the nature of winter hardening and the basis for winter injury in bermudagrass would give turf breeders a key to the development of winter‐hardy cultivars which are adapted for use as turf in transition areas where winter injury is like to occur. The purpose of this study was to compare three bermudagrass cultivars differing in winter survival morphologically and by chemical composition. The ‘U‐3’ cultivar was less cold hardy under conditions of the artificial freeze test than the ‘Midway’ and ‘Westwood’ cultivars at several sampling dates during the fall and winter. Midway had more rhizome and stolon tissue per unit area than the other cultivars which may give it some advantage for winter survival. Rhizomes of Westwood were thicker than those of Midway or U‐3. Total carbohydrates and sucrose increased in rhizomes and stolons during fall as hardening occurred. During winter sucrose increased slightly and reducing sugars remained constant while starch and total carbohydrate decreased. Carbohydrate differences among cultivars were slight and not related to winter survival. Stolons appeared to be the principal overwintering storage organ for carbohydrates and source of energy for regrowth in spring. Concentrations of total nitrogen, αNH2‐N, and nitrate N in overwintering tissue appeared to be dependent on the growth activity of the plants during fall and the date of the first killing frost. The U‐3 cultivar had higher total N, αNH2‐N and NO3‐N than the other cultivars. Ranking of cold hardiness of bermudagrass cultivars may be possible by combining morphological and chemical composition features into an index.
Chaudhary, T. N.; Bhatnagar, V. K.; Prihar, S. S.
doi: 10.2134/agronj1974.00021962006600010009xpmid: N/A
Information on crop response to depth and salinity of ground water and soil submergence is important for planning drainage and optimizing crop production. Response of a semidwarf wheat (Triticum aestivum L.) to four depths (60, 90, 120, and 150 cm) and three salinities (EC 0.5, 2.9, and 5.2 mmho/cm) of ground water was studied in lysimeters filled with silt loam soil during 1970–71 and 1971–72. The plants were irrigated with water of EC 0.5 mmho/cm when the lysimeters with a 150‐cm water table depth indicated a tension of 0.5 bar at a 75‐cm depth. Ground water of EC 0.5 mmho/cm at 60 and 90‐cm depths gave highest yields. Comparable increase in the salinity of ground water caused greater reduction in yield with shallow water tables than with deep water tables. It is indicated that critical depth of ground water, for optimum crop production, would vary in relation to its salinity.
Allen, L. H.; Hanks, R. J.; Aase, J. K.; Gardner, H. R.
doi: 10.2134/agronj1974.00021962006600010010xpmid: N/A
A method for computing CO2 uptake by an irrigated crop of wide‐row grain sorghum (Sorghum bicolor (L.) Moench, var. ‘RS‐610’) was devised from measured profiles of temperature, water vapor, and CO2 over the crop. The crop Bowen ratio, β and the ratio of photochemical heat flux density of carbon dioxide fixation to latent heat flux density, α, were determined from profiles of points, rather than from just two points. We call this method the profile Bowen ratio. The parameters α and β were used with the energy balance equation to compute the flux density of CO2 to the crop as a function of solar radiation, which itself was a function of time of day. CO2 flux density plotted as a function of solar radiation (or time of day) was lower at the highest radiation loads (midday) than at 1000 or 1400 hours. The lower CO2 flux density at midday may be the result of more mutual leaf shading in this crop geometry at high solar elevation angles. The CO2 flux density curve also showed concave curvature at the radiation loads concomitant with early morning and late afternoon hours when much of the solar energy was penetrating to ground in this east‐west row crop. Finally, computed daily CO2 fluxes were reasonably close to the CO2 equivalent of dry matter accumulation rates plus estimated respiration.
Showing 1 to 10 of 47 Articles