bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Sulfur Fertilization on Three Annual Range Species I. Laughlin Soil Experiment1
Authors: Shock Clinton C. , Jones Milton B. , Williams William A. , Center D. Michael
Published: July 2010

The fate of a single application of sodium sulfate and its effect on three range species grown alone and in pairs in free‐draining lysimeters containing Laughlin loam soil (fine‐loamy, mixed, mesic Ultic Haploxerolls) was monitored during two growing seasons. Plant growth responses to added S were small because the soil released considerable S during the course of the experiment, equivalent to more than half of the S application. However, the growth of subclover (Trifolium subterraneum L.) and its mixtures with fllaree [Erodium botrys (Cav.) Bertol.] and soft chess (Bromus mollis L.) was increased by S fertilization (P = 0.06). The botanical composition shifted towards subclover with added S. On the lysimeters where S was applied, subclover and filaree obtained more of their S from the applied fertilizer (55 and 55%) than did soft chess (44%). Total plant recovery of fertilizer sulfur in the 1st year was greater in pure stands of subclover (20%) than for soft chess (11 %) and filaree (7%). Total sulfur uptake was greatest on S fertilized lysimeters of subclover or sublover plus filaree. Leachate losses of S in the 1st year were positively related to the amount of S applied and volume of leachate and negatively related to S uptake by the plants. In the 2nd year leachate losses of S were positively related to the calculated S status of the soil at the end of the 1st year and negatively to plant S uptake. A greater leachate volume was lost from lysimeters containing filaree than containing soft chess or subterranean clover, and mixtures were intermediate. Leachate volume was not related to dry matter production. Sulfur application did not affect N uptake by the nonlegumes, but subclover N2 fixation was increased by 60% during the 1st year. The percentage of subclover N coming from N2 fixation was enhanced by the presence of nonlegumes. Estimates of recovery of fertilizer S were significantly less by calculations based on 35S and than on total S differences suggesting that the labile 35S is diluted in the soil solution by the release of non‐labeled S from decomposition of organic matter.
Nutritive Value of Seven Tropical Weed Species During the Dry Season1
Authors: Nuwanyakpa M. Y. , Bolsen K. K. , Posler G. L. , Diaz M. Q. , Rivera F. R.
Published: July 2010

Proliferatiion of weeds is a major constraint in pasture management, especially in the tropics, where fertilizers are rarely used and where poor grazing management is common. Nonetheless, grassland weed control should not be initiated indiscriminately without an evaluation of the palatability and nutritive value of the species present. One objective of a grazing trial conducted at Pichilingue, Ecuador, was to compare the palatability, in vitro dry matter digestibility, crude protein (CP) content, cell wall components, mineral and nitrate contents of seven weed species and four cultivated forages during the dry season. The weed species were Alternanthera gullensis (Mart.) Griseb (chaff flower), Amaranthus spinosus L. (spiny amaranth), Digitaria sanguinalis (L.) Scop. (large crabgrass), Eleusine indica (L.) Gaerth. (goosegrass), Momordica charanria L. (balsam apple), Sida acuta Burm. f. (southern sida), and Sida rhombifolia L. (arrowleaf sida).

Weeds were more digestible than cultivated forages, higher in CP and acid‐detergent lignin, and lower in neutral‐detergent fiber, acid‐detergent fiber, and silica. The Ca:P ratios in cultivated forages were close to the recommended 1:1 to 2:1 ratio. The only weed with a favorable Ca:P ratio was D. sanguinalis. The remaining weeds had Ca:P ratios of 3 to 7:1. During the dry season cattle were reluctant to graze the increasingly fibrous and protein‐deficient cultivated forages, so they consumed A. gullensis and A. spinosus, despite the very spiny texture of the latter. With the exception of D. sanguinalis for which palatability observations were not possible, cattle did not consume the other weeds. There were no symptoms of mineral imbalance or nitrate toxicity in cattle from grazing weeds. The practical implication of this study is that some weed species may be useful as feeds for grazing livestock during periods of limited feed supply, and should not be removed indiscriminately. Based on this study, A. gullensis and A. spinosus should not be removed from pastures during the dry season.
Stress Measurement Using Foliage Temperatures1
Authors: Walker G. K. , Hatfield J. L.
Published: July 2010

The total (stomatal and aerodynamic) conductance for water vapor of a crop (gv) reflects the rate of crop production. Determination of gv should therefore be valuable in predicting crop yield. With an energy balance approach to crop stress assessment, foliage‐air temperature differences (Tf — Ta) may provide a means of determining gv. This study was conducted to model the response of Tf — Ta to environmental parameters and conductances, and then, in a field experiment with kidney beans (Phaseolus vulgaris L.) grown under two radiation regimes, to determine gv using measured Tf — Ta values, and to relate this to crop yields. Kidney beans (‘Red Kidney’) were grown on deep Yolo clay loam (Typic Xerorthent) at Davis, Calif., under normal irradiance and with irradiance reduced by 50%. Different stress levels (different gv) were established by varying time and frequency of irrigation. Foliage temperatures (corrected for emissivity and sky radiation), net radiation and wet and dry bulb temperatures were recorded daily at ½ to 1 h after solar noon through most of the growing season. Seed yields were measured at the end of the season. The energy balance model and field data showed that Tf — Ta is sensitive to air saturation deficit (0.16°C mb−1) and to net radiation (0.5°C/100 W m−2). Using an energy balance scheme, calculations of gv were made from field data for the seed filling period. Relative yields estimated as gv/gmax, with gvmax determined from well‐watered plots, agreed well with relative seed yields (r = 0.75). Major Tf — Ta responses to saturation deficit and net radiation showed that Tf‐based crop stress estimates will not relate well to crop production unless these environmental parameters are accounted for, or unless they vary little between times of measurement. By using the energy balance, Tf — Ta measurements can be related explicitly to gv and, thereby, to crop production.
Nitrogen Distribution in Roots and Tops of Winter Wheat1
Authors: Smith T. L. , Peterson G. A. , Sander D. H.
Published: July 2010

The hypothesis has been proposed that the observed N losses from the aboveground parts of wheat (Triticum aestivum L.) near maturity might be explained by N redistribution to roots during the late grainfill period. This experiment was designed to test this hypothesis. Plant response to four N levels using a modified Hoagland's solution was studied in gravel culture. Roots and tops were harvested 12 times during the growth cycle and analyzed for N content. Nitrogen uptake patterns for roots and shoots were similar. At about 50 days after jointing (Feeke's Stage = 11.2) both roots and shoots began to lose N, while head N increased from anthesis to maturity. Gains in head N exceeded the amounts lost from the roots and shoots. So, N uptake from the culture solution continued through maturity. The hypothesis that N is redistributed to the roots near maturity in winter wheat was rejected. Roots were actually a source of N for translocation to the grain, as were aboveground stems and leaves.
Slope Position and Grain Yield of Soft White Winter Wheat1
Authors: Ciha A. J.
Published: July 2010

Winter wheat (Triticum aestivumL.) producers in the Palouse Region of southeastern Washington generally seed one wheat cultivar over a wide range of environmental conditions formed by the rolling topography of the area. A 2‐year field study was conducted during 1977–1979 growing seasons on five slope positions across a Palouse silt loam (fine‐silty mixed, mesic pachic Ultic Haploxerolls), a Naff silt loam (fine‐silty, mixed, mesic Ultic Agrixerolls), and a Snow silt loam (fine‐silty, mixed, mesic Cumulic Haploxerolls) to examine the influence of slope position on grain yield and yield components of 12 soft white winter wheat cultivars. Slope position and cultivar significantly influenced grain yield while only cultivar significantly influenced test weight. There were significant cultivar ✕ slope position and slope position ✕ year interactions for grain yield, test weight, and culm height. Differences in mean grain yield for an individual cultivar ranged from 0.45 to 1.90 Mg/ha when compared across slope positions. Yield components were examined during the 1977–1978 growing season and were found to be significantly influenced by slope position and cultivar. Spikelets/spike and 100‐seed weight were the only yield components to show a significant cultivar ✕ slope position interaction. These findings indicate the need to more clearly define where soft white winter wheat cultivars are best adapted to meet specific environmental and topography conditions.
Snap Bean Plant Responses to Nitrogen Fertilization1
Authors: Peck N. H. , MacDonald G. E.
Published: July 2010

Nitrogen fertilization may affect vegetative growth as well as yield and quality of pods of snap bean [Phaseolus vulgaris(L.) var. humilis] plants. A study was conducted to determine the effect of N fertilization on vegetative growth, N partitioning in the plants and production of pods on snap bean plants. Snap bean plants, Bush Blue Lake‐47, were grown under field conditions with N from ammonium nitrate at rates of 0, 4, 8, and 12 g m−2placed in a band 5 cm to the side and 5 cm below the depth of the seeds at planting time on 10 June 1981 in a Lima silt loam (fine‐loamy, mixed, mesic Glossoboric Hapludalf), a productive soil derived from calcareous glacial till. Rows were 50 cm apart with 22 productive plants m−1of row (44 plants m−2). The fresh weight, dry weight, total N and nitrate N were determined in different parts of the plants at the seedling, bloom, and pod stages. Yield and quality determinations were made on the pods at 10 and 13 August harvests. Fertilizer N decreased growth of the plants in the seedling stage but not by the pod stage. Fertilizer N reduced the number of rhizobium nodules on the roots. At the pod stage, total N was 15.7 g m−2in plants grown with residual available soil N but without fertilizer N, while total N was 19.5 g m−2in plants grown with residual soil N plus fertilizer N at 12 g m−2. Fertilizer N at 4 to 8 g m−2produced the optimum quality and yield of snap bean pods for processing.
Yield and Quality of ‘Caucasian’ and ‘Plains’ Bluestem Grasses as Affected by Clipping Interval1
Authors: Taliaferro C. M. , Horn F. P. , Ahring R. M. , Weeks D. L.
Published: July 2010

Use of introduced bluestems (Bothriochloaspp.) as pasture grasses in the southern Great Plains is increasing. Information is limited on the effects of management variables on the yield and quality of their forage. This field experiment was conducted on Pachic Paleustoll soil for 3 years (1974 to 1976), in order to assess the relative yield and quality of forage and stand persistence of the ‘Plains’ [B. ischaemum(L.) Keng. var. ischaemum] and ‘Caucasian’ [B. caucasica(Trin.) C. E. Hubb.] cvs. as affected by different clipping intervals (3, 5, 7,9, or 11 weeks between clippings). Cultivars were randomly assigned to whole plots and clipping intervals to subplots in a split‐plot, randomized complete block experiment. Significant differences due to cultivars were measured only in 1974 for dry matter (DM) and in vitro digestible dry matter (IVDDM) yields and in 1975 and 1976 for percent in vitro dry matter disappearance (IVDMD). The difference in 3‐year IVDMD of the cultivars (Plains = 60.1, Caucasian = 57.3) was also significant. Intervals between clippings affected DM and FVDDM yields and IVDMD each year. The DM and IVDDM yields increased as harvest interval increased from 3 to 7 weeks, where they generally peaked, but there was significant lack of fit to quadratic responses for DM and IVDDM yield in 2 of the 3 years. The IVDMD of the cultivars decreased linearly in 1974 and 1975 as clipping interval decreased. In 1976, the IVDMD response of the cultivars was different and deviated significantly from quadratic. The data suggest that the basic responses of Plains and Caucasian bluestem to clipping interval are characteristic of the responses of most forages. The length of the interval between harvests at which digestible dry matter will be maximized in a given year will vary with environmental conditions but probably would seldom exceed 7 weeks. Clipping interval had no effect on subsequent spring DM yield of the Caucasian cultivar but there was some reduction in first harvest DM yield of Plains due to frequent clipping during the previous season.
Effective Rates of Fertilization for Correcting Manganese Deficiency in Soybeans1
Authors: Mascagni H. J. , Cox F. R.
Published: July 2010

Manganese deficiencies occur in soybeans (Glycine max L.) grown on slightly acid to alkaline soils in the Atlantic Coastal Plain and efficient, effective corrective measures are needed. The optimum rate of Mn needed is not well defined for any method of application. Field studies were conducted to establish the most efficient rate for broadcast and band methods of soil application and for foliar application. The best time to begin foliar spraying and the number of sprayings required were also determined. Manganese sulfate was the Mn source. Manganese rate treatments for the broadcast, band, and foliar applications ranged from 0 to 90, 0 to 13, and 0 to 2.2 kg Mn ha−1, respectively. Optimum yields were obtained with broadcast Mn applied at 14 kg Mn ha−1 and band applications of 3 kg Mn ha−1. For foliar applications, rates as low as 0.1 kg ha−1 were sufficient, but spraying should begin as soon as symptoms appear and should be repeated at least once under severely deficient conditions.
Nitrate Monitoring for Cotton Lint Production on a Typic Paleudult1
Authors: Lutrick M. C. , Peacock H. A. , Cornell J. A.
Published: July 2010

Diagnostic criteria for monitoring the N status of both soil and cotton plant are needed to aid in adjusting N fertilization to compensate for seasonal variations. A 3‐yr study was initiated in 1981 to determine the feasibility of using soil and petiole NO−3–N testing as an aid in cotton (Gossypium hirsutum L.) lint production along the Gulf Coast. A factorial experiment with four rates of N, three rates of K, and four replications was established on an Orangeburg fine sandy loam (fine‐loamy, siliceous, thermic Typic Paleudult). Soil samples were taken each year just prior to the addition of N and K fertilizer treatments. Response to K fertilization was not significant. Cotton petiole samples were taken on selected plots for 9 weeks beginning 1 week prior to first bloom. The response to N resulted in a 3‐yr average maximum yield of 1294 kg ha−1 of lint cotton from 114 kg ha−1 of applied N. Petiole analyses for NO−3–N indicated that additional N should be applied to all treatments after the second week of petiole sampling, even though lint yields were above average in this study (average yield for this soil is 1008 kg ha−1). This suggests that the sufficient‐N zone established for petiole analyses of NO−3–N in Arkansas and accepted in Georgia is higher than is desirable for thermic Typic Paleudults. Repeated applications of N to the soil over the 3 yr of the experiment did increase the amount of NO−3–N extracted from the soil indicating that some of the applied N was not used by the cotton plant. A revised NO−3–N sufficient‐N zone, developed by Georgia researchers and first used in 1985, conforms with the data presented in this paper and could be used satisfactorily to determine N recommendations from petiole analyses for cotton lint production on thermic Typic Paleudults of the Gulf Coast of Florida.
Time Course of Nitrogen Fixation in Field‐Grown Soybean Using Nitrogen‐15 Methodology1
Authors: Zapata F. , Danso S. K. A. , Hardarson G. , Fried M.
Published: July 2010

The use of 15N techniques allows for the quantitative evaluation of N2 fixation and distribution and their impact on the N balance in various soil‐plant systems. The A‐value approach was used in this investigation to assess N2 fixed at various growth stages in fieldgrown soybean [Glycine max (L.) Merrill] cv. Chippewa in a Typic Eutrocrepts soil. At physiological maturity (R7), the amount of N derived from fixation (Ndfa) was 102 kg/ha, equivalent to 47% of total N assimilated, while the contributions from soil (Ndfs) and 15N‐labelled fertilizer (Ndff) accounted for 50 and 3%, respectively. Up to growth stage V6, which occupied half of the total duration of growth, Ndfa was less than 5% of N2 fixed by physiological maturity. A rapid increase in Ndfa occurred from R1 onwards, and during the reproductive stages (R1‐R4), which spanned less than one‐third of the total duration of growth, this represented about 45% of total Ndfa. An almost equal portion of N (approximately 43%) was fixed from pod‐filling (R5) to physiological maturity (R7), a period slightly more than one‐fifth of the total duration of growth. Therefore, substantial N2 fixation occurred during periods of active sink development and contributed more than 65% of the plant's N accrued during pod fill (R3‐R7). Nitrogen assimilated between R3 and R7 (when N2 fixation was high) seemed to be the predominant source of N for pod development. Thus there was a greater contribution from fixed N (55%) than soil N (43%) in pods and seeds at the end of R7. After grain removal, it was estimated that the growth of cv. Chippewa in this soil led to a net soil depletion of 54 kg N/ha.
Evaluation of Oxamide as a Slow‐Release Nitrogen Source on Kentucky Bluegrass1
Authors: Mosdell D. K. , Daniel W. H. , Freeborg R. P.
Published: July 2010

Slow‐release N fertilizers are used in turfgrass fertilization programs to reduce foliar burn and N losses, and to extend the response period between applications. In this study, oxamide (31% N), an amide of oxalic acid, and a 7:3 N ratio of oxamide and urea were evaluated as slow release N sources on Kentucky bluegrass (Poa pratensis L.) at West Lafayette, IN, on a Toronto silt loam soil (fine‐silty, mixed mesic, Udollic Ochraqualfs). Two particle sizes of oxamide, C (1–2.8 mm) and F (<0.85 mm), were applied as a granular and liquid suspension treatment, respectively. Additional treatments consisted of applying isobutylidene diurea (IBDU), sulfur‐coated urea (SCU), and urea. Two and four applications were made, with a total annual application rate of 196 kg N ha−1 yr−1. Recovery of N in the tissue from applications of oxamide C was 51% compared to 41, 39, and 38% for IBDU, oxamide F, and SCU, respectively, averaged over 3 yr. Initial change in visual turf quality and clipping yields in response to oxamide C was slow, similar to that of IBDU; however, residual N release was equal to that of IBDU and greater than that of SCU. Adding urea to oxamide C increased initial yields and turf quality but reduced the duration of turf response as compared to applications of oxamide C alone. At two applications of 98 kg N ha−1, oxamide proved to be a good, slow‐release source of N. At four applications per year, initial clipping yields resulting from spring oxamide F applications were lower than those from urea, but turf quality in response to residual N tended to be greater than that of urea. Late fall applications of oxamide F reduced soil NO−3 concentrations shortly after application and in early spring as compared to fall applications of urea. Oxamide F at four applications generally produced a more desirable turf response than did similar applications of urea.
Aerial Parts of Hard Red Spring Wheat. III. Nitrogen and Phosphorus Concentration and Content in Kernels, Anthesis to Ripe Stage1
Authors: Bauer Armand , Frank A. B. , Black A. L.
Published: July 2010

Information is lacking on N and P concentration and content in kernels of hard red spring wheat (Triticum aestivum L.) over the course of grain filling. Such information would be of benefit in making nutrient management decisions and provide algorithms for plant development/yield modelers. Concentration and content of N and P were measured twice weekly in composited kernels of all spikes from a 1‐m length of row, field‐grown on Williams loam (fine‐loamy, mixed Typic Argiborolls), during 3 crop years with fertilizer N rates, cultivars, and water management variables. Concentrations and contents were regressed with both days (DAYS) and growing degree‐days (GDD) accumulated from anthesis. With all treatments combined, the R2 relating kernel N and P concentration to DAYS was 0.45 and 0.49, respectively, and to GDD, 0.44 and 0.41, respectively. Peak N and P concentration, about 46.2 and 8.3 g kg−1, respectively, occurred within 1 to 2 DAYS after anthesis. Concentration at maximum kernel dry matter was 33.1 and 5.0 g kg−1 for N and P, respectively. The R2 relating kernel N and P content to DAYS was 0.95 and 0.92, respectively, and to GDD, 0.95 and 0.92, respectively. The N and P content increased about 30 µg N and 4.7 µg P kernel−1 DAY−1 during the constant‐rate phase of grain filling. Both N and P uptake closely paralleled kernel dry matter assimilation.
Evapotranspiration of Cool‐Season Turfgrasses in the Humid Northeast1
Authors: Aronson L. J. , Gold A. J. , Hull R. J. , Cisar J. L.
Published: July 2010

As competition for water increases in the northeastern United States, turfgrass culture must be directed toward practices that will lower water requirements. This study was conducted to quantify and compare the evapotranspiration (ET) rate of well‐watered grasses in the humid Northeast. Predictive methods for irrigation scheduling of turf were also evaluated. Weighing lysimeters, 0.25 m in diameter and 0.28 m deep, were placed into field plots of well‐watered mature turf growing on an Enfield silt loam (coarse‐silty over sandy‐skeletal, mixed, mesic Typic Dystrocrept), and ET was determined by weighing the lysimeters at 24‐h intervals throughout the summers of 1984 and 1985. The grasses studied were: Poa pratensis L, ‘Baron’ and ‘Enmundi’; Lolium perenne L., ‘Yorktown II’; Festuca rubra var. cummutata Gaud., ‘Jamestown’ and Festuca ovina var. duriuscula (L.) Koch, ‘Tournament’. Consistent annual differences were not observed in the variable summer weather that characterizes southern New England. Daily meteorological data were used to calculate reference ET by the modified Penman equation and from pan evaporation. A crop coefficient (Kc) was calculated for each grass as the ratio of ET measured to ET predicted. Seasonal Kc values based on the Penman equation ranged from 0.88 for Tournament in 1984, to 1.09 for Enmundi in 1985 (CV, 0.15–0.30). Seasonal Kc based on pan evaporation data was more variable, ranging from 0.86 to 1.31 (CV, 0.34–0.44). The Penman equation predicted ET more consistently, and could provide a reliable and useful tool for irrigation scheduling of turfgrass in southern New England.
Planting Date in Relation to Yield and Yield Components of Wheat in the Middle Atlantic Region
Authors: Rocheford T. R. , Sammons D. J. , Baenziger P. S.
Published: July 2010

A 2‐yr study was conducted to assess the effects of early and late planting on six soft red winter wheat (Triticum aestivum L.) cultivars. The purpose was to determine if increased flexibility in planting date is possible for modern wheat cultivars grown in the Middle Atlantic states. Wheat was planted 2 wk prior to, on, and 2 wk after the recommended fly‐free planting date at Clarksville (Piedmont Province) and Queenstown (Coastal Plain Province), MD. Grain yield and yield components (spikes per square meter, kernels per spike, and kernel weight) were measured. Planting date × location, and planting date × location × year interactions for grain yield occurred. At Clarksville, there were no significant differences in average grain yield among planting dates the first year, whereas a significant and progressive decline in average grain yield occurred with each delay in planting the second year. At Queenstown, early planted wheat produced a higher grain yield than wheat planted on the recommended and late planting dates the first year, whereas early planted wheat yielded less than wheat seeded on subsequent planting dates the second year. In general, changes in spikes per square meter were the major contributors to the yield differences observed among planting dates at both locations. Individual cultivars were variable in yield performance on the different planting dates. Although there was considerable environmental variation in crop performance, increased flexibility in planting date for winter wheat production in the Middle Atlantic states may be possible for certain wheat cultivars. Cultivar and environmental factors will play a large role in determining the success of such a change in current management practices.
Statistical Error Rates and Their Implications in Sugarcane Clone Trials
Authors: Glaz B. , Dean J. L.
Published: July 2010

There is an estimated difference of 18 h ha−1 in the amount of time required to cut the two most widely grown sugarcane (Saccharum spp.) clones in Florida, but this characteristic is neither analyzed nor considered in deciding if a clone should be released. The major objective of this study was to determine optimum type I and type II error rates (α and β levels) at which to perform significance tests for this characteristic at our current sample size and error variance (σ2). The minimum detectable difference (δ) was set at 18 h ha−1, the relative seriousness of type I versus type II errors was subjectively assessed, and the advantages and disadvantages of using various levels of α and β were then discussed. Analyses were performed for a group of 12 clones cultivated at five locations, from plant crop through second‐ratoon crop. It was determined most appropriate to use α = 0.10 so that β would approximate 0.04. The results indicate that at levels of α≤0.05, type II error rates are unacceptably high. For research projects in which type II errors have some negative consequences, researchers should estimate β at various a levels and set α at a level that appropriately balances type I and type II error rates.
Subterranean Clover Cover Crop Used to Increase Rice Yield
Authors: Dabney S. M. , Breitenbeck G. A. , Griffin J. L. , Hoff B. J.
Published: July 2010

Management systems for flooded rice (Oryza sativa L.) production that include a winter legume cover crop and no‐till planting are of interest to farmers seeking lower‐cost production methods. Field experiments were performed at Crowley and Baton Rouge, LA. The purpose was to determine the effects of N fertilization (0, 56, 112, and 168 kg urea‐N ha−1) and tillage (rototilling or no‐tillage) on the yield and yield components of rice planted in fallow plots or in plots containing subterranean clover (Trifolium subterraneum L.) that had produced mature seed. Rice was dry‐seeded 1 wk after clover was desiccated with an herbicide or tilled into the soil. A permanent flood was established 30 d after planting. The presence of a clover cover crop increased rice yields about 10% in tilled and no‐till plots receiving various rates of N fertilizer. Flag‐leaf N concentrations and the amounts of total N assimilated into above‐ground biomass at harvest were greater in rice after clover than in rice after fallow, but the presence of a winter clover cover did not reduce the amount of N fertilizer required to produce maximum yield. The maximum yields of rice obtained by no‐till management were similar to or greater than those obtained by tillage. After rice harvest, stands of reseeded subterranean clover were better in no‐till plots than in plots where clover residues had been incorporated into the soil prior to rice planting.
Pre‐emergence Flooding and Nitrogen Atmosphere Effects on Germinating Corn Inbreds
Authors: Khosravi Gh. R. , Anderson I. C.
Published: July 2010

This investigation was conducted to assess the relationship between sensitivity to pre‐emergence flooding and effects of anoxia on ethanol production and glycolytic activity in order to identify floodtolerant and flood‐susceptible corn cultivars. Seed of 20 common corn inbred lines (Zea mays L.) were exposed to different durations (0, 6, 12, 24, 48, 96, 144 h) of simulated anaerobic conditions in the laboratory or, immediately after planting, to flooding in greenhouse and growth‐chamber in two parts of bulk soil (glacial till parent materials) and one part sand. Percent seed germination and amount of produced ethanol, lactic acid, and dimethyl sulfide were determined after termination of anoxia in the laboratory; for greenhouse and growth‐chamber experiments, percent seed germination was determined after termination of flooding. The results indicated that ethanol production was negatively correlated with seed viability. Inbred corn line DE811, tolerant of flooding, regulated glycolysis so that there was minimal production of ethanol; inbred corn line MO17, intolerant of flooding and associated anoxia, was unable to regulate glycolysis, as indicated by production of large quantities of ethanol as the major end product of glycolysis. Lactic accumulation under the N2 atmosphere was low and did not seem associated with seed viability. Dimethyl sulfide liberation was associated with the intolerant MO17. This S‐containing volatile may be a product of seed metabolism, inasmuch as it occurs many metabolic changes as storage materials are hydrolyzed under anoxic conditions. Limitation of ethanol production may be the key to tolerance of low‐O2 environments.
Diurnal Variation of Crop Hydraulic Resistance: A New Analysis
Authors: Reid J. B. , Huck M. G.
Published: July 2010

Several explanations have been advanced to account for the apparent diurnal variation in crop hydraulic resistance (Rp) calculated from a simple Ohm's Law analog. In this paper, we suggest that Rp, calculated in this way, may vary because of spatial variation in soil water potential (Ψs). We propose that whenever transpiration rate (Q) is small and leaf water potential (Ψl) is relatively high, roots extract water mainly from those regions of the soil profile where Ψs is also high (usually deep in the profile). As Q increases and Ψl becomes more negative, roots begin removing water from regions of the profile where Ψs is more negative. Hence the length of roots actually taking up water at a particular time, and therefore Rp, may vary diurnally. Also, variations in Ψ3 and rooting density often make the relation between Ψl and water uptake rate unique for each soil region. So, even when all roots are taking up water, Ψl and the aggregated uptake rate may be nonlinearly related, and Rp will vary diurnally with Ψl. This theory is illustrated with exploratory calculations of Rp for hypothetical temperate cereal crops grown in three different soils (a clay, a silt loam, and a sandy loam), with various combinations of root system properties and evapotranspiration rates. Crop water content and root radial resistivity were assumed constant. Although Ψs was initially distributed uniformly in these simulations, heterogeneity in root distribution soon caused spatial variation in Ψs, and Rp showed marked diurnal variations. Variation in Rp increased with the predicted variation in Ψs. Detailed field experiments and simulation analyses are needed to quantitatively compare this and other hypotheses to explain diurnal variation in Rp.
Disease Enhancement and Kentucky Bluegrass Quality As Influenced By Fungicides
Authors: Dernoeden P. H. , McIntosh M. S.
Published: July 2010

Deleterious non‐target fungicide effects in turf need better documentation, while beneficial effects should be exploited. The main objectives of this field study were to identify turfgrass quality and non‐target disease enhancement effects of five fungicides applied to four Kentucky bluegrass (Poa pratensis L.) cultivars. Fungicides were applied monthly from April through September between 1983 and 1987 to turf grown on a Chillum silt loam (fine silty, mixed mesic Typic Hapludult). Quality of Kentucky bluegrasses (KBG) was improved significantly when fungicides controlled injurious diseases. Most notably, triadimefon [l‐(4‐chlorophenoxy)‐3,3‐dimethyl‐ l‐(lH‐1,2,4‐triazol‐l‐yl)‐2‐butanone] improved quality by providing therapeutic activity against stripe smut [Ustilago striiformis (West.) Niessl.] in ‘Merion’; and summer patch (Magnaporthe poae Landschoot and Jackson) in Merion and ‘Sydsport’ KBG. Chlorothalonil (tetrachloroisophthalonitrile) and thiram (bis[dimethyl‐thiocarbamoyl]disulfide) were associated with a significant increase in stripe smut in Merion, and chlorothalonil increased summer patch in Merion, Sydsport, and ‘Vantage’. Triadimefon and benomyl ([methyl l‐(butylcarbamoyl)‐2‐benzimidazoIe carbamate]) increased leaf spot [Drechslera poae (Baudys.) Shoem.] in ‘South Dakota‘ KBG. Iprodione [3‐(3,5‐dichlorophenyl>‐^V‐(l‐methylethyl)2,'Mioxo‐limidazolidinecarboxamide] did not exacerbate any disease, provided long residual leaf spot control, and elicited a color enhancement. Except for leaf spot in South Dakota, these non‐target increases in disease by fungicides did not recur annually in each cultivar.
High‐Temperature, Adult‐Plant Resistance to Wheat Stripe Rust and Effects on Yield Components
Authors: Schultz T.R. , Line R.F.
Published: July 2010

High‐temperature, adult‐plant (HTAP) resistance to stripe rust (Puccinia striiformis West) in wheat (Triticum aestivum L. em Thell) has remained durable for at least 30 yr in the USA. The expression of HTAP resistance to stripe rust in six crosses of winter wheat was evaluated using F6 populations at Pullman, WA in 1986 and F7 populations at three environmentally different locations (Pullman, Mt. Vernon, and Walla Walla, WA) in 1987. Resistant families could not be differentiated at Pullman in 1986 and Walla Walla in 1987 because unfavorable weather delayed the development of rust. Differences in rust intensity for families within each cross could be determined at Mt. Vernon and Pullman in 1987. Distributions of disease intensities for families of each cross were significantly different between the two locations. Negative correlations between three yield components (kernel number, kernel weight, and spike weight) and rust intensity at several plant growth stages were high when infection was early and rust intensity was severe, but were not significant when infection was late and rust intensities were moderate or low. Early rust development negatively affected kernel number. At Mt. Vernon, the plant growth stages at which yield components were most highly correlated with rust intensities varied depending on the cross. Most yield components were highly correlated with disease intensity at heading and milk stages. The environment at Pullman was appropriate and possibly better suited for selection of moderate or higher levels of HTAP resistance which are usually adequate for wheat grown in eastern Washington. Highly resistant families, however, could more easily be differentiated from moderately resistant families only under severe rust intensities that occurred at Mt. Vernon; thus an environment similar to Mt. Vernon is highly useful to select for the highest levels of HTAP resistance.
Incubation of Injected Liquid Beef Manure: Effect of Time and Manure Rate
Authors: Schmitt M.A. , Sawyer J.E. , Hoeft R.G.
Published: July 2010

An investigation was conducted to determine if N compounds and other chemical parameters that could cause poor corn (Zea mays L.) growth were associated with injected liquid beef manure. Liquid beef manure was injected into a Derinda silt loam soil (fine, mixed, mesic Typic Hapludalf) and incubated in two laboratory experiments. Experiment 1 consisted of two application rates, 18 and 36 mL kg−1 soil, injected into 25 g of moist soil and incubated for 44 d. Experiment 2 consisted of five manure application rates (0, 29, 58, 116, and 232 mL kg−1 soil, equivalent to 2.3, 4.6, 9.2, and 18.4 dry Mg ha−1) layered between 50 g of soil and incubated for 4 wk. Rates simulated the range of manure concentrations in band applications of 37200 L manure ha−1. There was a linear trend of increasing NH4–N concentrations as manure application rates increased. A transitory period of lowered soil redox potential (Eh) and elevated pH occurred for 2 wk after application, especially for the highest manure rate. Nitrite‐N accumulated with all rates of manure, but the accumulation was transitory with low manure rates. At 116 and 232 mL kg−1, high levels of NO2–N were present for 3 and 4 wk, respectively. Conditions potentially toxic to plants were generated initially by reducing conditions (as indicated by low Eh) and free NH3, (due to high pH and high concentrations of water extractable and exchangeable NH4‐N), and subsequently, by accumulation of NO4‐N.
Cropping History, Tillage, and Herbicide Effects on Weed Flora Composition in Irrigated Corn
Authors: Ball Daniel A. , Miller Stephen D.
Published: July 2010

A change from conventional tillage to a conservation tillage system can lead to shifts in weed species composition. A weed species shift can result in the emergence of weeds tolerant of existing weed management practices. An understanding of crop production effects on weed species shifts can lead to development of improved weed management strategies. Research evaluated the effects of primary tillage (moldboard and chisel plowing), row cultivation, and herbicide input level on weed species changes over a 5‐yr period in three irrigated cropping sequences. The cropping sequences consisted of continuous corn (Zea mays L.) for 5 yr (CN), pinto bean (Phaseolus vulgaris L.) for 3 yr followed by corn for 2 yr (PB), and sugar beet (Beta vulgaris L.) for 2 yr followed by corn for 3 yr (SB). Over the course of the 5‐yr study, total weed density increased from 1 to 245 weeds m−2 in PB, from 100 to 209 in SB, and from 2 to 190 in CN cropping sequences in chisel‐plowed treatments, while weed density increases in moldboard‐plowed treatments were negligible. General observation of each cropping sequence indicated that during the final year, green foxtail [Setaria viridus (L.) P. Beauv.] was most prevalent in the CN sequence, redroot pigweed (Amaranthus retroflexus L.) and hairy nightshade (Solanum sarrachoides Sendtner) in the PB sequence, and redroot pigweed and green foxtail in the SB sequence. However, weed species differences due to cropping sequences were evident only in treatments receiving chisel plow primary tillage. Further, the increase in redroot pigweed density due to cropping sequence and chisel plowing was diminished by high herbicide input levels. Row cultivation also had an influence on the weed species composition when compared to uncultivated plots.
Adjustment for Specific Leaf Weight Improves Chlorophyll Meter's Estimate of Rice Leaf Nitrogen Concentration
Authors: Peng Shaobing , García Felipe V. , Laza Rebecca C. , Cassman Kenneth G.
Published: July 2010

The chlorophyll meter provides a simple, quick, and nondestructive method to estimate leaf N status of rice (Oryza sativa L.), but the linear relationship between leaf N concentration on a dry‐weight basis (Ndw) and the meter reading differs depending on developmental stage and genotype. The objective was to determine whether prediction of (Ndw) with the chlorophyll meter can be improved by a simple correction for specific leaf weight (SLW). Leaf N status was estimated by a chlorophyll meter (SPAD‐502) and measured directly by micro‐Kjel‐dahl procedure. Specific leaf weight was calculated as the ratio of dry weight to leaf area. In one field study ‘IR72’, measurements were taken at midtillering, panicle initiation, and flowering stages on the uppermost fully expanded leaves of both N‐deficient and N‐sufficient plants. There was a linear relationship between Ndw and SPAD values at each stage, but regression lines differed significantly between growth stages. Based on pooled data from all stages, the degree of linear fit was poor (r2 = 0.49). Adjusting SPAD values for SLW (SPAD/SLW) improved the prediction of Ndw (r2 = 0.93). For another set of measurements made on the flag leaves of five genotypes grown in the field and greenhouse, prediction of Ndw was also improved, from r2 = 0.51 based on SPAD values alone to r2 = 0.87 based on the SPAD/SLW ratio. These results demonstrate that SLW influences the prediction of Ndw by the chlorophyll meter, and that the adjustment of SPAD values for SLW greatly increases the accuracy of the prediction. However, when SPAD values are adjusted for SLW, the chlorophyll meter's estimate of Ndw is no longer as quick, simple, or nondestructive as the nonadjusted SPAD values.
Core Cultivation and Efficacy of Benomyl Applied to Creeping Bentgrass
Authors: Liu Leon X. , Hsiang Tom , Eggens Jack L.
Published: July 2010

Hollow tine core cultivation is practiced for the management of creeping bentgrass [Agrostis stolonifera L. var. palustris (Huds.) Farw.; syn. A. palustris Huds.] golf course greens and fairways to increase water infiltration, increase turf root and shoot growth, and control thatch. Benomyl [methyl 1‐butylcarbamoyl)‐2‐benzimidazole carbamate] is commonly used on turf as a soil drench for the control of disease such as dollar spot (caused by Sclerotinia homoeocarpa F.T. Bennett). Our objective was to determine the effect of core cultivation on the movement of a systemic pesticide in thatch and soil and the uptake by turfgrass using benomyl as a model. Core cultivation was conducted 1, 7, and 14 d before benomyl application in a field trial during 1992 and 1993 to study the effect of coring and time of coring on the movement and uptake of benomyl and control of dollar spot disease. Fungicide levels in turfgrass clippings, thatch and soil were determined by bioassay. Core cultivation 1 d before benomyl treatment provided the longest lasting uptake of benomyl and control of dollar spot disease compared with 7 and 14 d before benomyl treatment. Clipping, thatch, and soil samples from areas close to the coring holes had significantly higher (P = 0.05) levels of fungicide residues than those farther from the coring holes. This study suggests that core cultivation shortly before benomyl application can increase movement of benomyl into thatch and soil, thereby increasing uptake of benomyl by turfgrass and improving disease control.
Establishment of Big Bluestem and Sand Bluestem Cultivars with Metolachlor and Atrazine
Authors: Masters Robert A.
Published: July 2010

Weeds interfere with big bluestem (Andropogon gerardii Vitman var. gerardii Vitman) and sand bluestem [Andropogon gerardii var. paucipilus (Nash) Fern.] establishment on rangeland and cropland in the central Great Plains of North America. A study was conducted to determine if metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylpbenyl)‐N‐(2‐methoxy‐1‐methylethyl)acetamide] and atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] applied preemergence could improve establishment of big bluestem and sand bluestem cultivars. ‘Bonilla’, ‘Pawnee’, ‘Kaw’, and ‘Rountree’ big bluestem and ‘Goldstrike’ sand bluestem were planted in late May to early June 1989 and 1990 near Clay Center [Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudoll)] and Mead [Hastings silt loam (fine, montmorillonitic, mesic Udic Argiustoll)] in Nebraska. Metolachlor at 2.2 or 3.3 kg a.i. ha−1 and atrazine at 2 kg a.i. ha−1 were applied alone or in combination before weeds or seeded grass cultivars emerged. Stand frequency (the number of times the planted grasses occurred within sampling grids and expressed as a percentage of the total number of grids evaluated) and yield of the grass cultivars were measured the year after planting to determine establishment success. Grass stand frequencies were usually >50%, with or without herbicide treatment. Yield of big bluestem and sand bluestem cultivars was increased by at least 30% when herbicides were applied preemergence the year of planting compared with yield without herbicide. For each cultivar, yield and stand frequency were similar when metolachlor or atrazine at 2.2 kg a.i. ha−1 were applied. Therefore, metolachlor is a suitable replacement for atrazine to improve establishment of big bluestem and sand bluestem cultivars. However, yield and stand frequency of most grass cultivars were maximized when metolachlor and atrazine were applied in combination.
A Peanut Simulation Model: II. Assessing Regional Production Potential
Authors: Meinke Holger , Hammer Graeme L.
Published: July 2010

An assessment of production potential over a broad geographical region is useful in industry planning. In this study, we present a method for combining crop simulation with spatial analysis to assess regional production potential. The Australian peanut industry, and its plan to expand production to new areas, is used as a case study to demonstrate the method. Using a peanut simulation model and historical climate records, irrigated potential peanut yields were simulated for a range of sowing dates at 53 locations throughout eastern Australia. The simulated median potential yield and feasible planting period at each location were used in a spatial interpolation routine to generate maps of regional production potential. The results were consistent with industry experience in traditional production areas and highlighted new areas with good potential for irrigated production. The analysis also showed the change in feasible planting period and optimal sowing date throughout the broad geographical region covered. The analysis considered only temperature and radiation effects on potential production. Other factors, such as disease incidence and water availability, must be considered in conjunction with these results when using them for industry planning. However, the methodology presented demonstrates how combining simulation analysis with simple spatial analysis can provide useful information to support industry planning.
Prediction of Ruminal Protein Degradability of Forages Using near Infrared Reflectance Spectroscopy
Authors: Halgerson James L. , Sheaffer Craig C. , Hesterman Oran B. , Griffin Timothy S. , Stern Marshall D. , Randall Gyles W.
Published: July 2010

Ruminal protein degradability is an important trait affecting forage quality, but in situ procedures used to characterize protein degradability are costly and time consuming. Our objectives were to compare an in situ procedure with a ficin protease extraction procedure for estimating ruminal protein degradability of forages and to determine whether near infrared reflectance spectroscopy (NIRS) can provide similar estimates of protein degradability compared to either method. Ruminal protein degradability of five cool‐season perennial grasses and alfalfa was determined using the ficin protease procedure. Ficin‐extracted crude protein (CP) represents that portion of CP that is solubilized in the extraction procedure; it accounted for 66% (in grasses) to 93% [in alfalfa (Medicago sativa L.)] of the variation of in situ degradable crude protein. NIRS accurately predicted in situ and ficin degradability on a dry matter basis, but not on a CP basis. We concluded that the ficin procedure could substitute for the in situ determination of ruminal degradable protein and that NIRS could be used to predict protein degradability determined by either method.