bluuebunny/crossref_metadata_2025 huggingface dataset:
Subsoil pH Effects on Growth and Yield of Cotton1
Authors: Doss B. D. , Lund Z. F.
Published: July 2010

Shallow root systems sometimes occur as a result of excessive acidity in the subsoil. So field studies were conducted to determine the effects of subsoil pH on growth and yield of unirrigated and irrigated cotton (Gossypium hirsutum L.) grown on a Rhodic Paleudult and to determine if normal yields could be obtained with a shallow root system when adequate water was supplied in the surface soil by frequent irrigations. The pH ranged from 4.4 to 6.2 in the 15 to 30‐cm soil depth. Subsoil pH of about 5.0 appeared to be the critical point for affecting root growth and yield on unirrigated cotton. Root growth was deep and yields were normal above 5.0, whereas rooting depth and seed cotton yield were progressively reduced with decreasing pH below 5.0. The reduced seed cotton yields, resulting from shallow root systems on acid subsoils, were overcome by frequent irrigation of the surface soil. Rooting depth and pattern were not affected by the irrigation.
Boron Application for Corn Grown on Selected Southeastern Soils1
Authors: Touchton J. T. , Boswell F. C.
Published: July 2010

Some southeastern states recommend Boron application or Corn (Zea mays L.) while others with similar soils, do not. Certain soils are capable of providing an adequate supply of B for plant growth; others are not and require additional B. This study was initiated to determine the effects of B application to corn grown on two Coastal Plain and one Piedmont soil. The objectives were to investigate B accumulation and distribution in the soil and plant tissue and the effect of B on yield, percentage of crude protein, and elemental concentrations in the plant and mature seed.

Field experiments were conducted to compare the effects of broadcast and foliar spray applications of B to corn at rates from 0 to 3.36 kg/ha. Hot‐water‐soluble (HWS) soil B and plant tissue B concentrations increased with increasing rate of B applications. Foliar spray application resulted in greater increases of B in tissue than the broadcast application. Boron accumulation in the marginal section of corn leaves was greater than accumulation in the midrib section. With the exception of corn receiving broadcast application of B at one of the Coastal Plain sites, B in the ear leaf tissue was significantly correlated with both HWS soil B and applied B.

There were no visual B deficiency symptoms but visual toxicities resulted from the two highest B rates for both application methods. The concentrations of P, K, Ca, Mg, Mn, Fe, Cu, Zn, Al, Sr, Ba, and Na were not affected by B applications. Yield and percentage crude protein in the grain were not affected by method or rate of applied B indicating that supplemental B is not required for corn grown on these soils.
Temperature, Time, and NH4Cl Concentration in Vigor Testing of Sorghum Seed1
Authors: Yayock J. Y. , Jan H. , Vanderlip R. L.
Published: July 2010

Often standard germination tests of sorghum seed over‐estimate field establishment capability. Current information in the literature points to the NH4Cl test as one of the most promising for correlating germination and field emergence for sorghum [Sorghum bicolor (L.) Moench]. But the potentiality of the test has not been conclusive, so we attempted to improve on the normally reported test procedure by changing temperature, time, and NH4Cl concentration. Laboratory and field studies were conducted in 1971, 1972, and 1973. Significant correlations generally were obtained between laboratory seed germination, including standard tests, and field emergence. For high correlations, NH4Cl concentrations need to be no more than 4% and soaking time no longer than 1 or 2 hours at 40 or 50 C, respectively, and germinating temperatures should be between 20 and 30 C. In one instance, correlation of field establishment with standard germination tests were higher than correlation with other germination tests, probably because of seed age. None of the modifications of the NH4Cl test greatly improved correlation with field establishment.
Changes of Multispectral Soils Patterns with Increasing Crop Canopy1
Authors: Kristof S. J. , Baumgardner M. F.
Published: July 2010

Computer‐aided data processing techniques were used to analyze multispectral data in order to map surface soil patterns and to follow the changes in multispectral radiation from a field of maize (Zea mays L.) during a period from seeding to maturity.

Panchromatic aerial photography was obtained before planting. Multispectral scanner missions were flown both before planting and on several dates after planting to obtain reflectance measurements in 13 wavelengths bands.

Reflectance measurements in the orange portion of the visible spectrum were used for grouping May and June data into seven different soil classes according to their spectral response. The reflective infrared spectral band was used in analyzing August data to separate maize into different spectral categories. Three selected bands of data were used to arrive at the resulting classifications.

The computer‐produced soil patterns had a striking similarity to the soil patterns of the aerial photograph. These patterns became less distinct as the canopy increased but remained visible. Changes in reflective infrared reflectance also indicated areas where the maize had deteriorated, due possibly to corn leaf blight infection.
Mounted Weighing System for Forage Plot Harvester
Authors: Baluch S. J. , Buker R. J. , Carter C. F.
Published: July 2010

A one‐man operated forage harvester was constructed by attaching a weighing basket from a hydraulic load cell to the self‐propelled Farmers Forage Research Plot Harvester. This new design allows the researcher to harvest a wide range of plot lengths and several different forage species with one machine. The weighing system was designed to reduce labor cost and harvesting errors accompanying alternative methods. The one‐man harvester was tested in the 1973 growing season on approximately 12,000 experimental plots and it demonstrated adequate precision, speed, and durability. We feel the initial cost and maintenance of this machine is completely justified and that it is a significant contribution to our forage program.
Root Size Variability Among Several Cultivars and Breeding Lines of Maryland Tobacco1
Authors: Aycock M. K. , McKee C. G.
Published: July 2010

Lodging of Maryland tobacco (Nicotiana tabacum L.) during the harvesting season may result in lower yields. ‘Maryland 609,’ a cultivar released in 1965, appears more susceptible to lodging than other cultivars. A previous root study with Maryland tobacco has been conducted in the field using the cultivars ‘Catterton’ and ‘Wilson’. These cultivars differed in root growth over a 10‐week period. Studies of this type, however, require considerable time and labor, and the number of plants one can study is often small. Therefore, a greenhouse study was conducted for 2 years with the following objectives: (a) to determine if a simple, but reliable, method could be utilized in the greenhouse for measuring size of tobacco roots, and (b) to determine the amount of variability present among the various Maryland tobacco cultivars for size of roots.

Three cultivars (Wilson, Catterton, and Maryland 609) were used in the study during the first year. The number of entries was expanded to six cultivars (Wilson, Catterton, Maryland 609, ‘Maryland 59,’ ‘Maryland 64,’ and ‘Maryland 10’) and three breeding lines (‘M871,’ ‘M872,’ and ‘M881’) during the second year. All entries were grown in clay pots 20.3 cm in diam filled with Galestown loamy sand (Psammentic Hapludult; sandy, siliceous, mesic). Plants were sampled approximately 20, 35, and 50 days after transplanting. Green weight, volume displacement, and dry weight data were obtained on roots and tops.

From these results, green weight measurements appeared to be the most simple and reliable for determining size of roots. Wilson had the largest root system of all entries for both years. Maryland 609 had the smallest root system of the three entries during the first year, and was among the group with the smallest roots during the second year. Breeding line M872 had the second largest root system as the plants reached maturity. The amount of variability for root size found among the cultivars and breeding lines suggests that some progress could be made through selecting for increased root size under greenhouse conditions. This increased root size should aid in reducing lodging as the plant reaches maturity.
Growth and Nutrient Accumulation and Distribution in Grain Sorghum. II. Zn, Cu, Fe, and Mn Uptake and Distribution1
Authors: Jacques G. L. , Vanderlip R. L. , Ellis Roscoe
Published: July 2010

Recognized, micronutrient‐deficiency symptoms in grain sorghum [Sorghum bicolor (L.) Moench] emphasize the need for micronutrient research in the crop. To conduct fertility trials and interpret plant tissue nutrient analyses, it is essential to understand nutrient uptake and distribution patterns. We investigated Zn, Cu, Fe, and Mn behavior in grain sorghum throughout its growth cycle. Two grain sorghum hybrids (‘RS 610’ and ‘RS 702’) were planted at the Kansas State University Agronomy Farm, Manhattan, in 1970 and 1971. Weekly samples of plant parts were analyzed for Zn, Cu, Fe, and Mn.

Nutrient concentrations in blade, sheath, culm, and head tissues generally decreased until maximum weight was reached and then stabilized or decreased only slightly and gradually as grain developed. Manganese in blade tissue, an exception, increased throughout the two hybrids' growth.

Whole plant nutrient concentrations decreased through most of plant growth. Zinc and Cu concentrations did not decrease so much during grain development as during vegetative growth.

Head tissue usually was lowest in nutrient concentration of all plant parts. Nutrient contents varied in other parts, but culm tissue was generally highest early in the sorghum's growth.

Hybrid RS 702 generally had a larger proportion of its nutrients in the vegetative portion than did RS 610. Differences occurred among plant parts in nutrient distribution, and uptake was not always proportional to dry matter accumulation.

Copper and Zn were translocated from vegetative plant parts to the head as grain developed, but Mn was not.

Nutrient uptake generally had reached 50% or more of total uptake in the plants when they completed vegetative growth. Nutrient uptake preceded dry matter accumulation. Differences between years and hybrids in total nutrient uptake occurred, but uptake curves were similar with definite, generalized patterns.
Postemergence Control of Kochia and Russian Thistle in Early Spring1
Authors: Smith D. T. , Wiese A. F. , Cooley A. W.
Published: July 2010

In semiarid regions, soil preparation precedes seasonal spring rains to conserve moisture. However, the early emergence of kochia [Kochia scoparia (L.) Schrad.] and Russian thistle (Salsola kali L. var. tenuifolia Tausch) severely competes with early‐seeded crops, such as sugarbeets (Beta vulgaris L.), or requires additional soil tillage prior to planting other crops. Objectives of this study were to evaluate postemergence control of kochia and Russian thistle for potential use in minimum till farming or postemergence control in established sugarbeets. Herbicides, with foliar activity, were applied at various stages of weed development in several field experiments on loam soil (mixed, thermic Paleustalfs and Paleustolls). Herbicidal efficacy was evaluated with regard to vegetative development of the weeds.

Early growth of kochia and Russian thistle was highly diverse in the spring, which would preclude herbicide applications at prescheduled calendar dates before planting crops. Herbicidal control with postemergence applications was best when weeds were small but growing vigorously. Of the herbicides evaluated, only paraquat (1,1′‐dimethyl‐4,4′‐bipyridlnimn ion) at 0.6 kg/ha consistently controlled both species. Complete postemergence control of kochia and Russian thistle was not feasible with diuron [3‐ (3,4‐dichlorophenyl)‐1,1‐dimethylurea], atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino) ‐s‐triazine]; herbicides which might also provide residual weed control in subsequent tolerant crops. In sugarbeets, kochia up to 2.5 cm tall, was effectively controlled with phenmedipham (methyl m‐hydroxycarbanilate m‐methylcarbanilate) at 1.1 or 1.7 kg/ha without injury to the crop.
Cottonseed Viability After Long‐Time Storage1
Authors: Stewart J. McD. , Duncan E. N.
Published: July 2010

Longevity of seed and knowledge of the conditions required to maintain seed viability are important in the preservation of germplasm. Cottonseed (Gossypium hirsutum L., G. barbadense L., G. thurberi Tod.) storage experiments were initiated in 1937 to establish conditions required to maintain long‐term viability of cotton. This is the final report of those experiments.

In one experiment, seed (G. hirsutum L.) of two cultivars were stored in sealed containers at moisture levels of 7, 9, 11, 13, and 14%, and at temperatures of 32, 21, and 0 C. For the last 10 years, only those seed stored near 0 C were carried forward, since all seed stored above this temperature were nonviable. Germination trials were conducted at 25 C for a 10 day period. Seeds containing 11% or less moisture and stored near 0 C had approximately 60% germination after 37 years.

In a related experiment cottonseed grown during the 1920's and 1930's in Arizona were tested for germinability. These seeds were stored unsealed at ambient temperature from the year of production until 1957. Thereafter they were sealed and stored cold. The oldest viable seed lots were produced in 1929 and had a maximum germination of 60% in 1974. Several of the pregerminated seed were grown to mature plants. This probably represents the oldest recorded viable cottonseed.
Field Studies of the Conductance of Wheat Leaves and Transpiration
Authors: Denmead O. T. , Millar B. D.
Published: July 2010

Light and water stress appear to be the main factors determining the short‐term variation of stomatal aperture in the field but their joint influences have seldom been studied in the natural environment. We have examined the effects of the irradiances and water potentials of leaves of field‐grown wheat plants (Triticum aestivum L. ‘Heron’) on their conductances for water vapor and on canopy transpiration.

Water potentials were measured by thermocouple psychrometry or estimated from water flow rates and plant resistances. Conductances were measured with a diffusion porometer or calculated from meteorological measurements inside the canopy. The latter data also permitted calculation of leaf irradiances and transpiration rates.

Provided leaf water potentials were higher than certain critical values (established by us in a previous study), leaf conductance (c cm s‐1) was linearly related to the net irradiance of the leaf (R1, W m‐2) by the equation c = 0.05 + 0.0020 R1, with a correlation coefficient of 0.90 and a standard error of estimate of 0.11 cm s‐1. This relationship applied to green leaves at all stem positions in the canopy up to a net leaf irradiance of > 500 W m‐2.

At and below the critical water potentials, stomatal aperture was controlled by leaf water status rather than irradiance. In cases of mild water stress, induced, for example, by an excessive evaporation demand, it appeared that leaf conductances decreased just sufficiently to keep water potentials at their critical levels, thereby limiting canopy transpiration to a maximum rate which, in our case, was 0.6 mm h‐1. In severe water stress, complete stomatal closure occurred at leaf water potentials about 10 bars less than the critical values and appeared to occur first in leaves at lower positions on the stem.
Foliar Fertilization of Soybeans During the Seed‐filling Period1
Authors: Garcia L. Ramon , Hanway John J.
Published: July 2010

Foliar fertilization of soybeans (Glycine max (L.) Merr.) with N, P, K and S during the seed‐filling period promises to increase soybean yields. Such foliar applications could be used to avoid the depletion of these nutrients in the leaves and the resulting reduction in photosynthetic rate during this period due to poor nutrient uptake from the soil and translocation of these elements from the leaves to the developing seeds. Field experiments were conducted to test this hypothesis by spraying soybeans with solutions of N, P, K, and/or S in different proportions and at different times and rates. We supplied N primarily as urea, P primarily as poly‐phosphate, K with the P as potassium polyphosphate or with the S as potassium sulfate. Very significant yield increases were obtained from two to four sprayings on different soybean cultivars at different experimental sites between developmental stages R5 and R7. The optimum proportion of N:P:K:S in the solution 10:1:3:0.5. a proportion similar to that of these elements in the seeds. The optimum rate of total nutrient application was about 80 + 8 + 24 + 4 kg/ha of N + P + K + S, respectively. Yield increases were due to increases in numbers of harvestable seeds, not seed size.

The results indicate that foliar fertilization during the seed‐filling period can become a very practical method for increasing soybean yields.
Amino Acid Patterns of Kidney Beans Grown Under Different S and K Regimes1
Authors: Hojjati S. M.
Published: July 2010

The protein of kidney beans (Phaseolus vulgaris L.), an important food crop, is poor in S‐containing amino acids and needs improvement. Solution and sand‐culture studies have shown that S fertilization increases the concentration of S‐containing amino acids in several crops. K application affects protein composition of some crops. The objective of this research was, therefore, to determine the amino‐acid concentrations of ‘Naze’ kidney beans and to study the effects of soil‐SO42‐ levels and K2SO4 application on grain yield and amino‐acid composition, especially the concentration of methionine.

An area of Xerollic Calciorthid, fine, vermiculitic, chermic soil which had been used previously for a S‐fertility study with wheat (Triticum aestivum L. em. Thell.) was used for this trial at Pahlavi University, Shiraz, Iran. The design of the experiment was a split plot with K2SO4, levels as main‐plot treatments and the prior S levels constituting the split‐plot treatments. (NH4)2HPO4 was applied uniformly at 200 kg/ha. Kidney beans were seeded at the rate of 75 kg/ha.

Proximate protein analyses were made by determining total N content and multiplying by a factor of 6.25. Tryptophan was analyzed colorimetrically and the other amino acids were determined in a Beckman Spinco amino‐acid analyzer. Chemical scores reflecting protein quality were calculated by FAO instructions.

Neither K2SO4 fertilization nor the prior S treatments had any effect on yield of dry matter or grain, ratio of grain to total dry matter, or grain‐protein concentration. Methionine concentration was positively correlated with soil‐SO42‐ level (r = 0.75; significant at the 1% level.). The first limiting amino acid was methionine, followed by valine and/or isoleucine. Tryptophan was not limiting. Regression equations for predicting methionine from soil‐SO42‐ levels and valine and tryptophan from total‐protein concentrations are presented.

Sulfur application may increase the methionine concentration of bean protein, but the large amounts of S required and the high costs involved appear to limit the usefulness of this approach for improving protein quality.
Influence of Terminal Bud Removal on the Growth and Seed Yield of Soybeans1
Authors: Bauer M. E. , Pendleton J. W. , Beuerlein J. E. , Ghorashy S. R.
Published: July 2010

In recent years soybean (Glycine max (L.) Merr.) yields seem to have reached an upper limit under prevailing moisture and temperature conditions using the current set of production practices. The present study was conducted to determine if changes in soybean growth resulting from removal of the terminal bud during vegetative or early reproductive stages of development would increase seed yield. The principal objectives were to determine if removal of the terminal bud of indeterminant varieties of soybeans would increase seed yields by 1) increasing the number of nodes available for pod set or 2) decreasing apical dominance. Several field experiments with treatments at different stages of development at time of bud removal, methods of removal, cultivars, seeding rates, and row widths were conducted during 2 years on Flanagan silt loam soil, a member of the fine, montmorillonite, mesic Aquic Argiudolls. Data were collected on height, lodging, maturity, number of branches, leaf area index, distribution of dry matter among pods and seeds, leaves, petioles, branches, and stems, seed yield, and 100‐ seed weight.

Removing the apical bud increased the number of nodes on branches and decreased the number of nodes on main stems, leaving the total number of nodes unchanged. The dry weight of vegetative organs was decreased by removal of the terminal bud, but seed yields were nearly constant. Removal of the terminal bud prior to the start of flowering increased branching and lodging, reduced leaf area index, and delayed maturity slightly. When the terminal bud was removed after the start of flowering, height, leaf area index, and lodging were reduced, compared to the control. The method of bud removal (hand‐pinching vs. mechanical‐mowing), cultivar, and planting density had little effect on growth and yield. From the data we concluded that, although the proportion of reproductive development compared to vegetative growth was increased by removal of the terminal bud, seed yields were unchanged.
Relationship Between Nitrogen Analysis of Soybean Tissues and Soybean Yields1
Authors: Pal U. R. , Saxena M. C.
Published: July 2010

In order to determine the applicability of N analysis of plant tissues as a diagnostic tool for N nutrition, it is essential to study the N status of soybean [Glycine max (L.) Merr.] plants under varying N supply. Field experiments were conducted to determine the effect of N fertilization at the rates of 0, 25, 50, 100, and 200, and 300 kg N/ha on the N concentration and accumulation in different plant parts of nodulating (inoculated and un‐inoculated) and non‐nodulating isolines of ‘Clark’ and ‘Harosoy’ soybeans at various stages of growth and to correlate the N status of soybean plants with yields.

The N concentration in stems, leaves, and petioles decreased with plant age, whereas in pods the N concentration increased. In contrast, N accumulation in stems, leaves, petioles, and whole plant followed a sigmoid pattern with plant development, while in pods it increased linearly. The rate of N accumulation (kg/ha/day) followed a bell‐shaped pattern and was maximum during the pod‐filling stage. Nitrogen fertilization had little effect on N concentration, amount of N in different plant parts or whole plants, N accumulation rate and seed yield/plant in inoculated nodulating isolines. However these attributes were increased conspicuously in non‐nodulating isolines and brought to the levels of inoculated nodulating isolines at higher rates of N fertilization (i.e., 200 and 300 kg N/ha). The uninoculated nodulating isolines were similar to non‐nodulating isolines in virgin soils for soybean cultivation.

Total N concentration and NO3‐N content of leaves showed better correlation with seed yields than total N accumulation in leaves/plant and total N accumulation/ plant. A total N concentration of 4.0% to 4.5% at 65 days was associated with highest yields in both ‘Clark’ and ‘Harosoy’. About 1900 ppm NO3,‐N content of leaves at 50 days in ‘Clark’ and about 1450 ppm NO3,‐N content of leaves at 65 days in ‘Harosoy’ were associated with highest seed yields. Based on the correlation values in different seasons for the two cultivars, total N concentration (%) seemed to be the best diagnostic criterion for N nutrition of soybeans.
Effect of Cultivar, Seeding Rate, and Nitrogen Fertilization on Kentucky Bluegrass‐Perennial Ryegrass Turf Mixtures1
Authors: Niehaus Merle H.
Published: July 2010

Perennial ryegrass (Lolium perenne L.) (RG)‐Kentucky bluegrass (Poa pratensis L.) (BG) mixtures, seldom recommended in the past, are becoming more popular since the development of several turf‐type RG cultivars. Older RG cultivars produce poor quality turf because of coarseness and poor mowing quality. The objective of this study was to determine whether a relatively new turf‐type RG cultivar can be grown in a mixture with BG without sacrificing turf quality.

A series of mixtures containing one of three RG cultivars (‘Manhattan,’ ‘Pelo,’ and ‘Linn’) and one of three BG cultivars (‘Pennstar,’ ‘Windsor,’ and ‘Kenblue’) was planted on a Typic Fragiudalf soil (Wooster silt loam) in the field in 1972. Three RG seeding rates (0.25, 0.5, and 1.0 kg/100 m2) and two N fertilizer rates (1.7 and 3.4 kg/100 m2) were used. BG was seeded at 1 kg/100 m2 on all plots. Botanical composition of the turf was obtained by counting BG and RG tillers in four samples from each subplot. Quality was determined by rating each subplot on a 1 to 9 scale.

The results indicated that Manhattan, a turf‐type RG, produced a high quality turf when mixed with any of three BG cultivars. Mixtures containing Linn, an older RG cultivar, were generally poor in quality but quality differed according to which BG cultivar was in the mixtures. Mixtures containing Manhattan RG or Pelo, an intermediate quality RG, were dominated by the RG, especially in the 2nd year, while those containing Linn RG were dominated by the BG.

Mixtures containing Windsor or Pennstar BG averaged higher in quality than those containing Kenblue BG. However, this difference was not apparent in mixtures containing Manhattan RG. Seeding rate had an effect on composition, primarily the 1st year. N rates were not associated with differences in quality or composition.

It is concluded that turf‐type RG can be used successfully in mixtures with BG.
Germination in Freshly Harvested Seed of Centipedegrass1
Authors: Bouton J. H. , Dudeck A. E. , Smith R. L.
Published: July 2010

Centipedegrass [Eremochloa ophiuroides (Munro) Hack.] is an important warm‐season turfgrass which can be established by seed. Germination of seed for progeny evaluation in the shortest time would be of value in a breeding program with this grass. Therefore, freshly harvested, open‐pollinated seed was used to study the effects of different temperature regimes and scarification treatments on percent and speed of germination.

Alternating temperatures of 35‐15 C with respective light‐dark periods of 12 hours each gave the highest percentage and fastest germination. Mechanical scarification greatly improved both parameters.
Residual Nitrate and Mineralizable Soil Nitrogen in Relation to Nitrogen Uptake by Irrigated Sugarbeets1
Authors: Stanford George , Carter J. N. , Westermann D. T. , Meisinger J. J.
Published: July 2010

Previously reported studies on N fertilization of sugarbeets (Beta vulgaris L.) in southern Idaho revealed considerable variation among sites in amounts of residual soil NO3 and N mineralized during short‐term laboratory incubations. Consequently, the amount of N fertilizer needed to achieve near‐maximum yields of sucrose differed markedly. The purpose of this study was to determine the feasibility of estimating amounts of N mineralized in the root zone during the season, taking into account site variations in temperature and soil water regimes. Residual soil NO3‐‐N and mineralizable N to approximate rooting depth were estimated for 21 field sites in 1971 and six sites in 1972. The relative contributions of these two N sources to total N uptake by the crop, in the absence of applied fertilizer N, were then assessed. Estimates of N mineralized in the upper 45‐cm soil layer for each successive month, ΔN, over a 6‐month period were derived using the expression, ΔN/ Δt = kWN (k = fraction of N mineralized during each month, Δt, adjusted for average air temperature; and W = the estimated soil water content expressed as a fraction of the available water storage capacity). Resulting estimates of the fraction of potentially mineralizable N converted to (NO3‐ + NH4‐)‐N between 1 April and 30 September ranged from 0.15 to 0.22 (mean ± S.D. = 0.18 α 0.02) in 1971 and 1972. On the average, mature sugarbeets recovered about 73% of the estimated N mineralized (6 months) plus residual NO3‐‐N. The relative contributions of these two sources of soil derived N, respectively, were approximately 66 and 75%, as estimated from multiple regression analyses.
Mn Concentration in Soybean Leaf Related to Bean Yields1
Authors: Ohki K. , Wilson D. O. , Boswell F. C. , Parker M. B. , Shuman L. M.
Published: July 2010

Correlation of Mn concentration in leaf tissue with seed yield for soybean (Glycine max (L.) Merr.) requires a nutrient calibration relating Mn concentration in tissue to seed yield under field conditions. The objectives of this study were to establish the relationship of Mn concentration and seed yield and the effect of sampling time on critical Mn level under field conditions. Soybean ‘Ransom’ was grown on Olustee‐Leefield sand (Ultic Haplaquod‐Arenic Plinthaquic Paleudult) with Mn rates of 0, 5.6, 11.2, 22.4, and 56 kg/ha. Leaf samples were taken at 4, 6, 9, 12, and 16 weeks after planting and the blades were analyzed for Mn.

The critical level of Mn in recently‐matured leaf blades for maximum bean yield was 7 to 10 μg/g for blades sampled at 4 to 9 weeks after planting. No substantial difference in critical Mn level was observed for the early sampling period of 4 to 9 weeks after planting. At the 12‐ and 16‐week sampling periods the critical Mn levels related to bean yield were 20 and 22 μg/g, respectively. The broad transition zone between deficiency and adequacy at the 12‐ and 16‐week sampling indicated reduced sensitivity in the Mn concentration and yield relationship. The recently matured blade (blade 2) on the main plant axis is suggested for sampling at the 9‐week period after planting for a representative indication of the Mn status of soybean under field conditions.
Effects of Cutting Management on Eight Subtropical Pasture Mixtures1
Authors: Murphy W. M. , Scholl J. M. , Baretto Ismar
Published: July 2010

Rhodesgrass (Chloris gayana Kunth) and ‘Pangola’ digitgrass (Digitaria decumbens Stent.) were grown with desmodium (Desmodium intortum (Mill.) Urb), glycine (Glycine jevanica L. ‘Tinaroo’), lotononis (Lotononis bainesii Baker), or ‘Siratro’ (Macroptilium atropurpureum (D.C.) Urb) on an Oxisol near Porto Alegre, Rio Grande do Sul. They were cut every 3 or 6 weeks at 5 or 13‐cm stubble heights to simulate different grazing pressures during two growing seasons. Herbage samples were hand separated to ascertain botanical composition. Crude protein (CP) and in vitro dry matter disappearance (IVDMD) analyses were determined for each species for cutting‐frequency treatments during the first year only. Cutting at 5 cm, at either frequency, increased legume content more than cutting at 13 cm. Exceptions were glycine, which increased most with rhodesgrass when cut at 13 cm, and ‘Siratro’, which decreased under all treatments when grown with ‘Pangola’. Legume contents increased from an average of 14% in the seeding year to 31% by the beginning of the third year. During the same period, grasses increased from 50% to 63% and weeds decreased from 36% to 5%.

Weed‐free, dry forage yields from all mixtures ranged from 1.24 to 7.26 metric/ha during the first year, and from 3.69 to 10.26 metric tons/ha during the second year. Yields generally were highest when mixtures were cut every 6 weeks at 5 cm, and were lowest when mixtures were cut every 3 weeks at 13 cm.

The CP concentration in legumes averaged 26% when they were cut every 3 weeks at either stubble height, and 23% when they were cut every 6 weeks. Concentration in CP in grasses averaged 15% for 3 weeks, and 13% for 6‐week cutting treatments. Yields of CP from mixtures ranged from 196 to 972 kg/ha. Yields of CP were greater from rhodesgrass mixtures than from Pangola mixtures, except for the Pangola‐desmodium mixture, which had CP yields equal to, or greater than, some rhodesgrass mixtures. Estimated digestible dry matter (EDDM), determined by IVDMD, in legumes averaged 54% when they were cut every 3 weeks at either stubble height, and 51% when they were cut every 6 weeks. EDDM in grasses averaged 73% for 3‐week cuttings. Yield of EDDM was greater from rhodesgrass mixtures than from Pangola mixtures. Considering all aspects studied, we believe that mixtures of rhodesgrass with desmodium or lotononis would be best choices for improving pastures in Rio Grande do Sul. Responses to cutting indicated that rhodesgrass‐desmodium should be grazed every 3 weeks to about a 13‐cm stubble height during the growing season. Grazing to higher stubble height, rather than the lower height, should result in a well‐balanced grass‐legume mixture for grazing. A well‐balanced rhodesgrass‐lotononis mixture should be maintained in a pasture by grazing every 3 weeks to about a 13‐cm stubble height, or every 6 weeks to either stubble height. Frequent, close grazing would probably result in higher percent legume in the mixture.
Serial Measures of Dry Matter Accumulation and Forage Quality of Leaves, Stalks, and Ears of Three Corn Hybrids1
Authors: Perry L. J. , Compton W. A.
Published: July 2010

Dry matter yields and forage quality of plant components (leaf, stalk, and ear) through maturity could vary among corn (Zea mays L.) hybrids. These potential differences could affect total forage quality yield and the hybrid choice for corn silage use. To compare plant composition, total plant dry matter, and forage quality among corn hybrids from flowering to physiological maturity, we studied leaf, stalk, and ear dry matter production and forage quality of three corn hybrids with maturity. Three corn hybrids, ‘Nebr. 611’, ‘Nebr. 612’, and ‘Nebr. 712’, were grown under field conditions with optimum agronomic conditions on a Sharpsburg silty clay loam (Typic Argiudolls) soil and harvested at six kernel development stages within 9 weeks following flowering during 1973 and 1974. All forage was separated for leaf, stalk, and ear dry matter production, and analyzed for crude protein, and in vitro dry matter disappearance (IVDMD). Total plant dry matter production increased at most harvests both years for all hybrids. Hybrid 712 yielded significantly more forage than 611 and 612 for most harvests. Stalk dry matter production declined over the harvests both years while leaf production increased during 1973. Leaf production remained the same over the harvests in 1974 for hybrids 611 and 612. Ear dry matter production increased at each harvest for all hybrids both years. Leaf crude protein was twice as large as stalk crude protein and declined over all harvests for the leaf component. Percent crude protein of ears declined through the first three harvests only. No hybrid differences were detected in percent crude protein of the three yield components. Leaf IVDMD was higher than that of stalk IVDMD. Rate of IVDMD decline was greater in stalks than leaves. Leaf IVDMD was consistently higher in 712 than 611 or 612. Little change occurred in ear IVDMD over the six harvests, however, the values were significantly greater in 1974 than 1973. The greatest plant protein and IVDMD yield occurred at the last harvest, physiological maturity, both years for all hybrids. Variation was detected among hybrids for total plant dry matter and plant component yields but less variation was detected among hybrids in forage quality for each plant component.
Transpiration Effects on Leaching Fractions1
Authors: Meiri A. , Kamburov Josephine , Shalhevet J.
Published: July 2010

Water uptake by plants during the processes of infiltration and redistribution may introduce considerable errors in actual leaching when calculations are based on pre‐irrigation soil water deficit. The objective of the study reported here was to measure and demonstrate the importance of this water uptake in causing a reduction in the actual leaching.

Experiments were conducted with sunflower plants (Helianthus annus L.) using containers with screen bottoms which drained into dry soil. The soil below the container was changed before each irrigation. Both saline (32 meq/liter NaCl + 16 meq/liter CaCl2) and non‐saline water were used at six leaching fractions (0.1 to 0.4). Drainage was doubled when plants were covered with plastic bags to suppress transpiration. Water uptake during leaching reduced the intended leaching fraction by 51 and 42% in the non‐saline and saline treatments, respectively (mean for all treatments).

Measured chloride content in the containers was similar to that calculated from salt balance. The chloride concentration in the highly leached top soil indicated a 20% water uptake during flow.

The results indicate that calculations of water application depth for leaching should not be based on soil moisture deficit but on the actual evapotranspiration of the crop. This is particularly true, for high frequency irrigations and for high transpiration rates.
Field Response of Four Tropical Legumes to Lime and Superphosphate1
Authors: Snyder G. H. , Kretschmer A. E. , Sartain J. B.
Published: July 2010

The generalization is often made that tropical legumes show little or no response to lime, even in acid soils low in Ca. Phosphorus responses, however, are generally observed. The effect of lime in an acid, virgin spodosol (Oldsmar fs) in southern Florida plots was investigated. Significant yield responses to lime and P were observed. Maximum total annual dry matter production of centro (Centrosema pubescens Benth.), desmodium (Desmodium heterocarpon DC.), stylo (Stylosanthes guyanensis Swartz), and ‘Siratro’ (Macroptilium atropurpureum Urb.) required lime applications of about 2,200 kg/ha. Regression analyses suggested that centro and Siratro might respond to higher lime rates if combined with P rates higher than those used in the study. Calculated optimum P rates ranged from 45 to 78 kg/ha, with desmodium requiring the least. Liming beyond the optimum rate appeared to seriously reduce production of desmodium and stylo.
Evaluation of Nitrapyrin as a Means of Improving N Efficiency in Irrigated Sands1
Authors: Hendrickson L. L. , Keeney D. R. , Walsh L. M. , Liegel E. A.
Published: July 2010

The efficiency of fertilizer N is usually low when potatoes (Solanum tuberosum L.) are grown on irrigated sands, because of rapid leaching of NO3. The objective of this research was to determine if optimum levels of N might be maintained throughout the growing season by delaying nitrification with a nitrification inhibitor, Nitrapyrin [2‐chloro‐6‐(trichloromethyl)pyridine] (NI). This method would increase fertilizer N efficiency and also reduce the potential for groundwater contamination. Several field experiments were conducted on a Plainfield loamy sand (Typic Udipsamment; sandy, mixed, mesic) involving various N sources, rates, and times of application with and without NI. Potato tuber yield and the forms and distribution of N in and below the fertilizer bands were determined. Nitrapyrin extended the persistence of applied NH4 in all experiments, but inhibition of nitrification was of relatively short duration. Nitrapyrin persistence was likely reduced by the more rapid volatilization and hydrolysis in sandy soils. Further, the effectiveness of NI was likely limited by rapid leaching of NH4 out of the NI‐treated zone. Application of NI reduced both total tuber yield and the proportion of marketable tubers. The greatest reductions were found on treatments receiving NI both at planting and at sidedress. The soil sampling data showed that NI maintained a much higher NH4‐N/NO3‐N ratio than comparable non‐NI treatments. It appears that the predominance of NH4‐N interfered with plant metabolism so that both yield and normal development of tubers were impaired.
Effect of Foliar Fertilization on Photosynthesis, Leaf Nutrition, and Yield of Soybeans1
Authors: Boote K. J. , Gallaher R. N. , Robertson W. K. , Hinson K. , Hammond L. C.
Published: July 2010

Foliar fertilization (FF) was reported to increase seed yields of soybean [Glycine max (L.) Merr.] in field experiments in Iowa, but yield increases were not consistent. The researchers hypothesized that FF should minimize nutrient depletion from leaves during seed development, and thereby delay the resulting decrease in leaf photosynthesis. To test this hypothesis, we conducted a field experiment in 1976 to determine the effect of FF on leaf element concentrations, gross leaf photosynthesis (Pg), and soybean seed yield. Five weekly foliar sprays were applied during the seed‐filling period of ‘Bragg’ soybean grown at Gainesville, Florida on Kendrick loamy sand (loamy, siliceous, hyperthermic grossarenic paleudult). At weekly intervals, we sampled upper leaves and total canopy leaves and analyzed them for N, P, and K, and measured Pg of upper leaves in mid‐day sun with a 14CO2 gas flow technique. Foliar applications of N, P, K, and S increased the N, P, and K concentration of total canopy leaves from 3.28, 0.24, and 0.92% to 3.48, 0.29, and 1.32%, respectively. FF significantly increased upper leaf Pg only at two late sample dates when seed growth was nearly complete and most leaves had already senesced and dropped. Even though nutrient concentrations were increased, FF did not significantly affect yields nor did it extend Pg duration or delay maturity. Treated soybeans yielded 3617 kg/ha compared to 3825 kg/ha for control soybeans. Leaf Pg and concentrations of N and P in leaves progressively decreased during seed‐filling until maturity but K did not decline. Leaf Pg was positively correlated with N (r = 0.87) and approached zero at approximately 1.75% N, a concentration similar to that of senesced, recently abscised leaves. Maximum Pg was predicted at 4.6 to 6.0% leaf N. Leaf Pg and percent P were also positively correlated. The relationship of Pg to leaf N during N removal from leaves can potentially be used to model photosynthetic decline during seed‐filling.
Flowering, Abortion, and Yield of Early‐Maturing Soybeans at Three Densities1
Authors: Dominguez Carlos , Hume D. J.
Published: July 2010

Attempts to extend the northern limits of soybean [Glycine max (L.) Merr.] production in North America are hampered by low yields. The earliest‐maturing genotypes are small, short‐statured plants. Their size suggests that yields could be increased by raising the plant population. In these trials, the early‐maturing genotypes, ‘Fiskeby V’, ‘052–903’, ‘Altona,’ and ‘Vansoy’, were grown in 30‐cm row widths at 40, 80 and 120 plants/m2 in 1975 and 1976 in a silty clay loam (Aquic Hapludalfs). The objective was to determine the influence of seeding rates on flower and pod production, abortion, yield components, and seed yield. Total flowers produced and initial and final numbers of pods per plant were decreased at high densities. The percentage of reproductive structures aborted also increased. More abortion occurred during the flowering period than post‐flowering period. The number of pods per plant was the yield component most affected by increasing density. The planting to flowering period, duration of flower production, number of seeds per pod, and seed size were cultivar characteristics not affected by density treatments. Final seed yields averaged 2,740 kg/ha over the 2 years. Seed yield increased by about 190 kg/ha when density was increased from 40 to 80 plants/m2 and by another 100 kg/ha when density was increased from 80 to 120 plants/m2. These responses represented only about twice the extra seed planted. The middle one‐third of the plants on a plant height basis produced an average of 44% of the seed yield. Increasing density decreased the percentage contribution of the bottom portion of the plant to final yield. Fewer bottom pods would be beneficial in reducing harvest losses with small, early‐maturing soybeans.
Recovery of Corn Leaf Water Potential After Severe Water Stress
Authors: Nulsen R. A. , Thurtell G. W.
Published: July 2010

The re‐establishment of vegetative growth after a period of water stress depends on the recovery of leaf water potential after rewatering. If the time to achieve recovery can be reduced, then overall plant production can be increased. This investigation examined the rates and patterns of leaf water potential recovery in corn plants (Zea mays L.) after alleviation of differing degrees of water stress. The experiments were done in a controlled environment chamber on corn plants grown in 5‐liter pots of 1:3 mixture of silica sand:calcined clay. Leaf water potential was measured in situ with a thermocouple dewpoint hygrometer. Plants were stressed by withholding water and, immediately upon rewatering, the growth chamber lights were turned off and the recovery pattern in the dark was monitored. Leaf water potential of corn plants stressed to −10 to −11 bars recovered in the dark 40 to 50 min after rewatering. When the plants were stressed to water potential values less than −11 bars they took between 95 and 300 min to recover. The recovery pattern always showed a distinct plateau phase during which time leaf water potential was relatively stable. The plateau occurred beween −9 and −7 bars and lasted 30 to 45 min. No plateau phase was observed in the rate of change of stalk diameter, but when stalks of severely stressed plants were severed under water to initiate recovery, we did not observe a plateau phase. Severing stalks under water, while leaf water potential was on a plateau, resuited in an immediate increase in potential. Applying pressure to the roots during the plateau phase caused af water potential to shift off the plateau. When pressure was released, however, the potential returned to the plateau and the plant continued a normal plateautype recovery. The results indicate that the main factors responsible for the plateau phase were in the roots, but that the stem and the leaves exerted some minor effects.
Value of Manure and Sewage Sludge as N Fertilizer1
Authors: Pomares‐Garcia F. , Pratt P. F.
Published: July 2010

A greenhouse pot experiment in a Hanford soil (Typic Xerorthent) with rates of feedlot manure at 0, 20, 40, and 60 metric tons/ha and sewage sludge at rates of 0, 10, 20, and 30 metric tons/ha combined factorially with 0, 50, 100, 150, and 200 mg N/kg of soil as (NH4)2SO4 was conducted using barley (Hordeum vulgare L.) and sudangrass (Sorghum sudanense (Piper) Stapf.) as test crops. The objectives were to measure the net mineralization of N in the organic materials, to compare the availability of N in the organic materials with the N in (NH4)2SO4 and to determine the critical levels for N and NO3 in barley. The available N from the organic materials was estimated from the amounts required to equal the N in (NH4)2SO4 in terms of barley forage production. Net mineralization was determined by soil analyses.

Yields of barley forage were increased by additions of organic materials and (NH4)2SO4. The addition of either manure or sludge decreased the response to (NH4)2SO4. In a 2.5‐month period after application, the manure gave an average of 0.65 kg of available N/ton, whereas the sludge gave 7.05 kg of available N/ton. This represents 4.2% of the total N from the manure and 17.0% of the total N in the sludge. In a 10‐month period only 17.2 and 40.9% of the N in manure and sludge, respectively, had mineralized.

The estimated critical levels of total N and NO3−‐N in barley forage were 2.0 and 0.12%, respectively. These values were independent of the N source. The minimum content of total N in barley forage at which NO3−‐N began to increase was about 2.0%. The level of NO3−‐N in plant tissue was more sensitive than total N to changes in N supply.