bluuebunny/crossref_metadata_2025 huggingface dataset:
Agronomic Responses of Corn Hybrids from Different Eras to Deficit and Adequate Levels of Water and Nitrogen
Authors: O’Neill Patrick M. , Shanahan John F. , Schepers James S. , Caldwell Bob
Published: July 2010

Maintaining current high yields of corn (Zea mays L.) grown in the USA poses an environmental threat due to continued overuse of water and N inputs. To reduce overreliance on inputs, future corn breeding efforts should focus on improving tolerance of corn to water and N stresses, utilizing appropriate tolerance mechanisms. The objective of this study was to identify appropriate mechanisms by characterizing agronomic responses of 12 hybrids from three different eras (‘B73 × Mo17’ from 1970s and three early 1990s and eight late 1990s Pioneer brand hybrids) to varying water and N supply. This was done by growing the hybrids under deficit and adequate levels of water (one‐half and full evapotranspiration) and N (0 and 200 kg ha−1) in a field study and measuring yield and other agronomic variables. While hybrid eras didn’t differ in response to varying water or N, individual hybrids varied in ability to maintain yield under water or N stress. For example, under deficit water, ‘3417’ produced 27% more yield than ‘3162’ while they yielded similarly under adequate water. Likewise, under deficit N, ‘34R07’ produced 42% more grain yield than ‘33G27’ while they yielded similarly under adequate N. Agronomic variables such as kernel number per unit area were highly correlated with grain yield (r = 0.98), indicating hybrid ability to maximize kernel number under varying water and N supply was critical to maximizing yield. Determining physiological mechanisms associated with ability to maintain kernel number under stress should be a high priority of breeding programs.
Switchgrass and Big Bluestem Hay, Biomass, and Seed Yield Response to Fire and Glyphosate Treatment
Authors: Sanderson M. A. , Schnabel R. R. , Curran W. S. , Stout W. L. , Genito D. , Tracy B. F.
Published: July 2010

Timing of spring fire and glyphosate [N‐(phosphonomethyl)glycine] treatments is critical to control weeds without compromising production of warm‐season grasses. To determine the forage and seed yield response we burned or applied glyphosate to switchgrass (Panicum virgatum L.) and big bluestem (Andropogon gerardii Vitman) in mid‐April, early May, and late May in 1998 and 1999 at Rock Springs, PA. Compared with fire in mid‐April or early May, a late May burn in 1998 reduced July dry matter yields (simulating a hay harvest) by 40 to 48% but did not affect dry matter yields in September (simulating a biomass feedstock harvest) of either grass. In switchgrass, glyphosate applied in late May reduced July yields by 70% and September yields by 30%. In bluestem, late May application of glyphosate reduced July yields by 90% and September yields by 40%. In both grasses, fire in late May reduced yields less than a late May application of glyphosate. Late May glyphosate treatments reduced seed yield compared with the mid‐April date. We conclude that in central Pennsylvania switchgrass or bluestem can be burned through the first week of May (10–15 cm growth) with little effect on hay or biomass yield. Glyphosate should be applied (i) before mid‐ to late April (just before green‐up) if switchgrass or big bluestem is to be harvested as hay in July or for seed in September, or (ii) by the first week of May if the cumulative growth is to be harvested once in autumn.
Tillage and Residual Nitrogen Impact on Wheat Forage
Authors: Wiatrak P. J. , Wright D. L. , Marois J. J.
Published: July 2010

Wheat (Triticum aestivum L.) forage yield and quality can be affected by management of the previous crop. The objective of this study was to evaluate two tillage systems [no‐till (NT) and conventional (CT)] and residual response to four N rates (0, 67, 134, and 202 kg ha−1) applied to the previous cotton (Gossypium hirsutum L.) crop. The experiment was conducted on a Dothan sandy loam (fine, loamy siliceous, thermic Plinthic Kandiudults) in 1995–1996 and 1996–1997. Greater wheat dry matter yields were obtained from CT than NT in 1995–1996 (6.3 and 5.4 Mg ha−1, respectively), while tillage did not influence yields in 1996–1997 (7.5 and 8.0 Mg ha−1 for CT and NT, respectively). Wheat yields were not influenced by N application to the previous cotton crop. The in vitro organic matter digestion (IVOMD) was not influenced by tillage or N application to the previous cotton crop. With increasing N application to a previous cotton crop, neutral detergent fiber (NDFt) and neutral detergent ash‐free (NDFaf) increased in wheat forage under CT and decreased in NT. Nitrogen concentration of wheat increased with N application to the previous crop. Concentration of P was greater from CT than NT in 1995–1996, while tillage did not influence P concentration in 1996–1997 growing season. Increasing N application rates to the previous crop decreased NDFt and NDFaf in wheat grown in NT and increased N concentration in dry matter of wheat grown in both tillage systems. Generally, NT is a viable option for growing wheat forage following cotton.
Calibration of Shielded Net Radiometers
Authors: Fritschen Leo J. , Fritschen Charles L.
Published: July 2010

Net radiation is an important term because of its use in water balance and other studies. Faulty data results from net radiometers that are not calibrated properly. Using the total shading method to calibrate shielded net radiometers (NRs) results in faulty calibration coefficients because large negative net radiation is included in the results. The proposed partial shading method corrects this problem and yields valid calibration coefficients. Outdoor calibrations are time consuming and require clear skies that are rare in many areas. We propose laboratory methods, requiring less time, for precise and repeatable short‐ and long‐wave calibrations. A detailed model of a shielded NR was used to compute the magnitude of the various heat transfers from each side of a transducer. Under high net radiant conditions, the sensible heat transfer upward from the transducer averaged 22% larger than downward. This gave rise to the need for separate calibration coefficients for daytime conditions (heated surface facing upward) and for nighttime conditions (heated surface facing downward). The effect of wind speed on the signals of several net radiometer designs was investigated. The results indicate that NRs should be ventilated when they are calibrated and for precise measurements.
Selection of Optimum Reflectance Ratios for Estimating Leaf Nitrogen and Chlorophyll Concentrations of Field‐Grown Cotton
Authors: Zhao Duli , Reddy K. Raja , Kakani Vijaya Gopal , Read John J. , Koti Sailaja
Published: July 2010

Leaf N and chlorophyll (Chl) concentrations of cotton (Gossypium hirsutum L.) are important indicators of plant N status. Laboratory determinations of plant tissue N are time consuming and costly. Measurements of leaf reflectance may provide a rapid and accurate means of estimating leaf N and Chl. Studies were conducted to determine the relationships between leaf hyperspectral reflectance (400–2500 nm) and Chl or N concentration in field‐grown cotton. One study consisted of four N rates of 0, 56, 112, and 168 kg N ha−1, and another study consisted of four mepiquat chloride (MC) rates of 0, 0.59, 1.17, and 2.34 L MC ha−1. Chlorophyll and N concentrations and reflectance of uppermost, fully expanded mainstem leaves were measured throughout the growing seasons. Reflectance at 556 and 710 nm increased significantly as N fertilizer rate decreased. Averaged across years and sampling dates, the percentage increase in reflectance at these two wavelengths was 8, 10, and 19% greater in the 112, 56, and 0 kg N ha−1 treatments, respectively, compared with the 168 kg N ha−1 treatment. The effect of MC on leaf reflectance was more complex than the N effect. In both the N and MC studies, a linear relationship was found between leaf N and a simple ratio of leaf reflectance at 517 and 413 nm (R517/R413) (r2 = 0.65–0.78***). Leaf Chl concentration was associated closely with reflectance ratios of either R708/R915 or R551/R915 (r2 = 0.67–0.76***). Our results suggest leaf reflectance can be used for real‐time monitoring of cotton plant N status and N fertilizer management in the field.
Trade‐Offs in Forage and Seed Parameters of Annual Medicago and Trifolium Species in North‐Central Texas as Affected by Harvest Intensity
Authors: Muir James P. , Ocumpaugh William R. , Butler Twain J.
Published: July 2010

The trade‐off between early spring harvest of cool‐season annual forage legumes and summer seed production may shed light on subsequent yearly stand regeneration. Sixteen annual clover and medic cultivars or locally collected accessions were seeded in the autumn of 1999 at Stephenville, TX, on a Windthorst (fine, mixed thermic Udic Paleustalf) fine sandy loam and allowed to self‐reseed in the autumn of 2000 and 2001. During the first 2 yr, three harvest treatments were imposed: harvest at 5 cm from crown whenever branches reached 10 cm from crown, harvest at 10 cm when branches attained 15 cm, and a single April harvest. Forage yields showed a year × species interaction (P = 0.001) and ranged up to 6 Mg ha−1 yr−1. Plants harvested in April only were consistently more productive than the 5‐cm harvest and yielded nearly 4.9 Mg ha−1 in Year 1. Forage acid detergent fiber and crude protein concentrations reflected entry × harvest × year interactions (P < 0.05). Seed yields varied considerably among entries, and all the annual clovers and most medics were able to self‐reseed regardless of harvest treatment, showing promise for self‐reseeding, sustainable pasture systems in the southern Great Plains.
Can Topographical and Yield Data Substantially Improve Total Soil Carbon Mapping by Regression Kriging?
Authors: Kravchenko A. N. , Robertson G. P.
Published: July 2010

Accurate mapping of total soil C on the field scale is essential for evaluating efforts to sequester soil C and for providing individual producers with information on C sequestration potentials of their fields. Data on easily measured secondary variables that are strongly related to soil C are believed to be helpful in improving mapping accuracy. The objective of this study was to assess improvement in mapping accuracy due to dense topographical and long‐term yield monitoring information. Approximately 1200 total C measurements at the 0‐ to 5‐cm depth along with topographical and 7‐yr crop grain yield data were collected at twelve 60‐ by 60‐m plots at the Long‐Term Ecological Research Site in Michigan. Total C was found to be significantly related to topography and 7‐yr average standardized yield in all studied plots, with regressionR2>0.5 in approximately half of the plots. Accounting for either topographical or yield information in regression kriging, however, produced only modest (<10%) improvement in mapping accuracy compared with ordinary kriging. Plots with promisingly strong relationships of total C with topography or yield were also found to be the ones where spatial distributions of total C were highly continuous, thus leading to no advantages in using regression kriging. The results indicated that under soil and topographical conditions similar to those of this study, dense topographical data or dense long‐term yield data might not lead to substantial improvement in C mapping accuracy.
EVALUATION OF DAIRY MANURE NITROGEN‐15 ENRICHMENT METHODS ON SHORT‐TERM CROP AND SOIL NITROGEN BUDGETS
Authors: Powell J. Mark , Kelling Keith A. , Muñoz Gabriela R. , Cusick Paul R.
Published: July 2010

Indirect estimates of manure N availability to crops are highly variable. We developed two methods that label dairy manure N components with the stable isotope 15N for direct measurement of manure N availability to crops. The forage method involved the labeling then feeding of 15N‐enriched forage to dairy cows (Bos taurus) to label urine N, fecal endogenous N, and fecal undigested feed N. The urea method involved the direct feeding of 15N‐enriched urea to label urine N and fecal endogenous N. Manure from each enrichment method was applied to a Plano silt loam (fine‐silty, mixed, mesic, Typic Argiudolls) using field plots in 1999 and 2000; corn (Zea mays L.) was grown for 2 yr after each application. No significant differences were observed in manure 15N recoveries in corn, soil inorganic N, or soil total N due to manure application year or manure enrichment method. Corn took up 14 to 16% of manure 15N the first year and 4 to 8% the second year after application. Most 15N recovery in soil inorganic and total N was found in the upper 30 cm of soil, indicating little downward movement of applied manure 15N. On average, 68% of applied manure 15N was accounted for, either in crop uptake (21%) or in the soil (47%). The less laborious and less costly urea enrichment method may be adequate for short‐term (2 yr or less, the range of this study) manure–soil–crop–N cycling studies. Longer‐term studies may need to include fecal undigested feed 15N derived from the forage enrichment method.
Evaluating the CROPGRO Soybean Model for Predicting Impacts of Insect Defoliation and Depodding
Authors: Timsina J. , Boote K. J. , Duffield S.
Published: July 2010

Insect feeding on leaves, pods, and seeds causes significant yield loss in soybean [Glycine max (L.) Merr.]. Robust soybean growth models would be helpful to simulate the effect of defoliation or depodding on soybean growth and yield. The objective of this study was to evaluate the CROPGRO‐Soybean model for its ability to predict the impacts of insect defoliation and depodding. Growth data were used to calibrate the model for two cultivars in Griffith, NSW, Australia. The model was evaluated against independent data from defoliation and depodding experiments at Griffith and at Gainesville, FL. The work tested the sensitivity of the model to defoliation and depodding at various growth stages, by comparison to data on manual defoliation of 30 and 60% in Australia and 30 and 70% in the USA, and depodding of 50 and 100% in Australia. The model predicted small yield reductions (4–11%) from 30% defoliation and greater reductions (17–49%) from 60 to 70% defoliation. The model illustrated well the pattern of sensitivity to defoliation: low during vegetative growth, increasing until beginning seed growth, and decreasing thereafter. The model overpredicted yield loss for severe defoliation but predictions improved after model modification to include photosynthetic contribution of green area of stems, petioles, and pods. Depodding predictions were generally accurate, but showed the need to evaluate model ability to add late pods after depodding. We conclude that the CROPGRO‐Soybean model has adequate capabilities for use as a tool to predict the effects of timing and intensity of defoliation and depodding.
Evapotranspiration Measurement in Controlled Environment Chambers: A Comparison between Time Domain Reflectometry and Accumulation of Condensate from Cooling Coils
Authors: Timlin Dennis , Fleisher David , Kim Soo‐Hyung , Reddy Vangimalla , Baker Jeffrey
Published: July 2010

The measurement of water fluxes from canopy and soil surfaces is performed in sunlit controlled environment chambers by measuring condensate draining from cooling coils in a constant humidity environment. This provides a direct measure of evapotranspiration (ET). However, in growth chambers with soilbins, this does not give information on soil water status or root activity. The objective of this study was to compare ET measurements from the condensate system with ET calculated from measurements of water content by TDR. Data from an irrigation × carbon dioxide (CO2) study on potato (Solanum tuberosum L.) were used for this study. The soil water contents in the growth chamber soilbins were monitored once an hour at five vertical depths with three measurement locations per depth using an automated TDR system. The correspondence between daily ET rates for the two systems was good. Maximum daily ET rates were near 6.1 to 7.1 mm cm−2 d−1 (7–8 L d−1 on a chamber basis) and differences were on the order to 0.89 to 1.8 mm cm−2 d−1 (1–2 L d−1). At the higher daily ET rates, the daily values from the two methods were closer. The correspondence between hourly measurements of ET measured from the condensate system and calculated from TDR water contents was poor due to instrument and soil variability. A significant source of error was vertical variation in water content in the soil between horizontally placed TDR probes, especially during irrigation events. Evapotranspiration estimates from TDR measurements were much more robust for calculation of water use over a period of time. Data from the condensate system were most useful for quantification of diurnal transpiration rates and were better correlated with radiation.
Management Practice Effects on Surface Soil Total Carbon: Differences along a Textural Gradient
Authors: Hao X. , Kravchenko A. N.
Published: July 2010

Management practice and soil texture are known to affect soil C. Relatively little information exists, however, on interactions between textural and management effects. The objective of this study was to evaluate management effects on soil total C along a textural gradient in well‐drained Typic Hapludalfs in southwest Michigan. Three management practices considered in this study were conventional tillage (CT) and no‐till (NT) both with conventional chemical inputs, and conventional tillage with leguminous cover crops and no chemical inputs (CT‐cover). Four replicate plots were sampled for each practice, with approximately 100 soil samples taken at the 0‐ to 5‐cm depth in each plot. In all management practices, the relationships of total C and N with clay + silt varied depending on the range of clay + silt values, with regression slopes at clay + silt <570 g kg−1 being 1.5 to 6 times lower than those at clay + silt >570 g kg−1. Total C in the CT‐cover and NT treatments was higher than that in the CT treatment across the whole range of studied textures; however, a greater difference in total C between NT and CT occurred at greater clay + silt contents. Total C in the CT‐cover and NT treatments were not different when clay + silt was <600 g kg−1, while the NT treatment had higher total C than the CT‐cover treatment when clay + silt was >600 g kg−1. The results indicate that the potential for C accumulation in surface soils via NT treatment depends on soil texture.
Use of Nitrogen‐15 Isotopic Techniques to Estimate Nitrogen Cycling from a Mustard Cover Crop to Potatoes
Authors: Collins H. P. , Delgado J. A. , Alva A. K. , Follett R. F.
Published: July 2010

Farmers in the Pacific Northwest are using cover crops such as white and brown mustards (Brassica hirta) in rotation with potatoes (Solanum tuberosum L.) because it reduces potential wind erosion and serves as a biocontrol method for a number of plant pathogens. However, there is no information about the N cycling from the mustard cover crop to potato. We used a 15N isotopic crop residue exchange technique to assess this N cycling potential in situ. We conducted two 15N field studies from 2001 to 2004 in the Columbia Basin in eastern Washington on a Quincy sandy (Xeric Torripsamments) soil containing 4 g kg−1 soil organic matter under center pivot sprinkler irrigation to assess the fate and N cycling from a mustard cover crop to potato. The established rotation at the site was a winter wheat (Triticum aestivum L.)–sweet corn (Zea mayes L.)–sweet corn–potato rotation. The aboveground mustard cover crop recovered 34 to 51% of the 56 kg 15N fertilizer applied. The total aboveground biomass and N uptake by the cover crop ranged from 4.6 to 7.5 Mg ha−1 and 92 to 142 kg N ha−1, respectively. About 29% of the N in the cover crop was cycled and absorbed by the following potato crop. This study shows that the mustard cover crop can provide 30 to 40 kg N ha−1 toward the N requirement of a subsequent potato crop.
Effects of a Grass‐Selective Herbicide in a Vetch–Rye Cover Crop System on Corn Grain Yield and Soil Moisture
Authors: Clark A. J. , Meisinger J. J. , Decker A. M. , Mulford F. R.
Published: July 2010

Cover crop spring kill date and species affect spring water use by covers, summer moisture conservation by cover crop residue, and yield of subsequent corn (Zea mays L.). Data are needed on spring management strategies for cover crop mixtures of hairy vetch (HV) (Vicia villosa Roth) and cereal rye (Secale cereale L.), compared to pure stands, to make accurate corn fertilizer nitrogen (FN) recommendations and to optimize moisture use vs. conservation by cover crop mixtures. A 2‐yr study evaluated a grass‐selective herbicide (GSH) applied in late March to a pure rye cover and a vetch–rye mixture, allowing the vetch to accumulate N until early May. These treatments were compared to early May‐killed pure rye, pure vetch, vetch–rye mixture, and no‐cover control. Corn FN rates of 0, 45, 90, 180, and 270 kg ha−1 were applied in June. Corn grain yield was greater following pure stands of vetch than following any other cover crop treatment, regardless of kill date. The average economic optimum FN rate was about 150 kg N ha−1 without a cover. With a cover crop and compared to the control, the hairy vetch replaced about 80 kg FN ha−1, the vetch–rye mixture replaced about 15 kg FN ha−1, while the pure rye removed an additional 50 kg FN ha−1. Spring soil moisture (0–20 cm) beneath growing covers was greater than or equal to the no‐cover controls throughout the spring and the summer. There was no significant difference in corn FN response for the early kill date of rye with a GSH, compared with the conventional late‐kill date.
Early‐Season Applications of Sulfur Fertilizers Increase Potato Yield and Reduce Tuber Defects
Authors: Pavlista Alexander D.
Published: July 2010

Sulfur recommendations are based on avoiding deficiency. Since S may have additional effects, the objective was to determine whether S fertilizers increase yield and reduce tuber defects. Potato (Solanum tuberosum L.) cultivar Atlantic was treated with wettable sulfur (WS), ammonium sulfate (AS), and ammonium thiosulfate (TS) at 0, 28, 56, 84, and 112 kg S ha−1 applied at planting [in‐furrow (IF)], 11 d later [pre‐emergence (PE)], 11 d after emergence [postemergence (PT)], and at tuber initiation (TI). Separate trials were conducted for each fertilizer and application. Ammonium nitrate and urea were added to AS and TS to equalize N. Yield of U.S. “A” potato was increased 11 to 34% by fertilizers at S rates greater than 56 kg ha−1 at IF, PT, and by AS and WS at TI. These fertilizers applied IF and at TI reduced the incidence of common scab (Streptomyces scabies) on tubers. When applied PT, AS and TS reduced common scab; WS did not. The incidence of black scurf (Rhizoctonia solani) on tubers was reduced when AS and TS were applied PT but not when applied IF and at TI. Pre‐emergence application had no effect. Other tuber characteristics, e.g., specific gravity and vascular discoloration, were unaffected. Plant growth was inhibited by TS applied after emergence but recovered. Yield was increased by S at 56 kg ha−1 applied IF, PT, and at TI except for TS applied at TI. Common scab and black scurf were reduced depending on application timing and fertilizer.
WEATHERINFO: A WEB‐BASED WEATHER DATA CAPTURE SYSTEM
Authors: Steiner Jeffrey J. , Minoura Toshimi , Xiong Wen
Published: July 2010

Past and current weather data are needed for many agriculture and natural resource management applications. With the rapid development and popularity of web technology solutions, the Internet has become a major means for collecting and presenting information. The WeatherInfo system prototype was developed as a framework platform to provide end users a way to automatically retrieve weather information over the Internet to support simulation models or other applications needing these kinds of data. To make data retrieval and manipulation easy by users, WeatherInfo was implemented with a relational database to store weather data extracted directly from the U.S. National Weather Service (NWS) website. The database is automatically updated daily. Based on daily updated data, weekly and monthly data are automatically calculated using the daily updated data. The system also includes a Web service implemented in ASP. NET to support data retrieval by clients who desire weather data in either graphic or table form. The system framework was set up to demonstrate data retrieval over the web from the NWS website (http://www.nws.noaa.gov; verified 22 Oct. 2004) for 19 locations in California for periods from 1 February 2003 to the present date. The WeatherInfo system demonstration can be accessed at: http://yolo.een.orst.edu/WeatherInfo/index.htm (verified 22 Oct. 2004).
Pre‐Sidedress Nitrate Test and Other Crop‐Based Indicators for Fresh Market and Processing Sweet Corn
Authors: Ma B. L. , Subedi K. D. , Zhang T. Q.
Published: July 2010

Commercial sweet corn (Zea maysL.) production requires significant quantities of fertilizer N, leading to inefficient N use and negative environmental impact. A field experiment was conducted for 4 yr (2001–2004) in Ottawa, Canada, to assess and compare presidedress soil nitrate test (PSNT) with some crop‐based measurements (canopy reflectance, leaf chlorophyll and plant total N) for improved N management. A fresh market sweet corn (FMSC, hybrid ‘Temptation’) grown from 2001 to 2003, and a processing sweet corn (PSC, hybrid ‘Hollywood’) from 2002 to 2004, both received five fertilizer N rates (0, 50, 100, 150, and 200 kg N ha−1). Soil samples taken from the V4 to V8 growth stages were analyzed for NO3−–N. Leaf chlorophyll content (SPAD) and canopy reflectance were also measured for FMSC at the same time. All N treatments affected the number of marketable ears, kernel dry weight and total biomass production. However, in most cases, there was no difference between N treatments from 100 to 200 kg ha−1. The PSNT NO3−–N increased linearly with the fertilizer N rates, and there were significant positive correlations between PSNT at V4 to V6 and the number of marketable ears. It was evident that PSNT, plant N concentration at V6, SPAD and canopy reflectance all differentiated sweet corn N response similarly, and they were highly correlated with one another. We concluded that PSNT at V4 to V6 was effective in predicting sweet corn N requirement in this cool and short‐growing region.
Dynamic Cropping Systems for Sustainable Crop Production in the Northern Great Plains
Authors: Tanaka D. L. , Krupinsky J. M. , Merrill S. D. , Liebig M. A. , Hanson J. D.
Published: July 2010

Producers need to know how to sequence crops to develop sustainable dynamic cropping systems that take advantage of inherent internal resources, such as crop synergism, nutrient cycling, and soil water, and capitalize on external resources, such as weather, markets, and government programs. The objective of our research was to determine influences of previous crop and crop residues (crop sequence) on relative seed and residue yield and precipitation‐use efficiency (PUE) for the no‐till production of buckwheat (Fagopyrum esculentum Moench), canola (Brassica napus L.), chickpea (Cicer arietinum L.), corn (Zea mays L.), dry pea (Pisum sativum L.), grain sorghum (Sorghum bicolor L.), lentil (Lens culinaris Medik.), proso millet (Panicum miliaceum L.), sunflower (Helianthus annus L.), and spring wheat (Triticum aestivum L.) grown in the northern Great Plains. Relative seed yield in 2003 for eight of the 10 crops resulted in synergistic effects when the previous crop was dry pea or lentil, compared with each crop grown on its own residue. Buckwheat, corn, and sunflower residues were antagonistic to chickpea relative seed yield. In 2004, highest relative seed yield for eight of the 10 crops occurred when dry pea was the previous crop. Relative residue yield followed a pattern similar to relative seed yield. The PUE overall means fluctuated for seven of the 10 crops both years, but those of dry pea, sunflower, and spring wheat remained somewhat constant, suggesting these crops may have mechanisms for consistent PUE and were not as dependent on growing season precipitation distribution as the other seven crops. Sustainable cropping systems in the northern Great Plains will approach an optimal scheme of crop sequencing by taking advantage of synergisms and avoiding antagonisms that occur among crops and previous crop residues.
Soil Water Depletion and Recharge under Ten Crop Species and Applications to the Principles of Dynamic Cropping Systems
Authors: Merrill Stephen D. , Tanaka Donald L. , Krupinsky Joseph M. , Liebig Mark A. , Hanson Jonathan D.
Published: July 2010

Dynamic cropping systems principles require that farmers consider climatic, market, and ecological factors on an annual basis in making crop choices. Our objectives were to determine variability of seasonal soil water depletion (SWD) and spring soil water recharge (SWR) among crops and to apply results to dynamic cropping systems practice. A 10‐species crop sequence project was conducted under no‐tillage on silt loam Haplustoll soils in North Dakota. Mid‐May to mid‐September SWD and following April SWR were determined from 2002 to 2005 by neutron moisture meter to the 1.8‐m depth. Crops studied and average SWD amounts (cm) were: sunflower (Helianthus annuus L.), 13.5; corn (Zea mays L.), 12.6; sorghum [Sorghum bicolor (L.) Moench], 11.0; spring wheat (Triticum aestivum L.), 10.6; canola (Brassica napus L.), 10.0; millet (Panicum miliaceum L.), 9.6; buckwheat (Fagopyrum esculentum Moench), 9.4; chickpea (Cicer arietinum L.), 8.5; lentil (Lens culinaris Medik), 8.1; and dry pea (Pisum sativum L.), 5.0, with highest and lowest being 29 and 11% of average May soil water, 46 cm. Because the period of the experiment was relatively dry, recharge was less than depletion. Spring soil water was 10 cm greater following pea than following sunflower. Ranking of crops for water storage roughly followed reverse SWD rank, with several exceptions, notably wheat, which had greater water from snow capture. Lower soil water following crops such as sunflower and corn was linked to negative crop sequential effects in this project. Choosing to seed a lower water‐using crop in the spring after the occurrence of below‐average SWR on land that had a higher water‐using crop the previous season illustrates an application of information reported here along with the principles of dynamic cropping systems.
Planting Date and Nitrogen Effects on Fusarium Head Blight and Leaf Spotting Diseases in Spring Wheat
Authors: Subedi K. D. , Ma B. L. , Xue A. G.
Published: July 2010

Cultural management practices play important roles in minimizing losses caused by Fusarium head blight (FHB) and leaf spotting diseases (leaf‐spot) in wheat (Triticum aestivum L.). A field experiment was conducted in Ottawa, Canada, for 3 yr (2003–2005) in two sites representing clay loam and sandy loam soils to examine the effects of planting date and N management on the incidence and severity of FHB and leaf‐spot {tan spot, Septoria leaf blotch and Stagonospora nodorum blotch) in spring wheat. The cultivar AC Brio was seeded at three dates at approximately 10‐d intervals starting in the last week of April. The five N treatments included 0, 60, and 100 kg N ha−1 applied as starter; 60 + 40 kg N ha−1 (starter + top‐dress at boot stage); and 60 + 40 kg N ha−1 (starter + foliar spray at boot stage). Generally, incidence of FHB and severity of leaf‐spot were greater in the heavy‐textured soil than in the light‐textured soil. Across site–year, the incidence of FHB ranged from 13 to 45%, and severity varied from 14 and 52%. On both soils, planting date had a consistently greater effect on the incidence and severity of FHB: the later the planting date beyond 9 May, the greater the incidence of FHB. The late‐planted wheat also had the greatest severity of leaf‐spot. Planting after 9 May also significantly reduced grain yield by 15 to 45%. Wheat grown without added N had the greatest incidence of FHB and leaf‐spot severities than that supplied with adequate N, especially in the heavy‐textured soil. The effect of N on FHB was not consistent over site–years, but leaf‐spot was significantly reduced with a starter application of N at 100 kg ha−1. Our data indicate that environmental variation induced by different planting dates or by different growing seasons and site appeared to have greater effects on FHB and leaf‐spot in wheat than N application. The results suggest that the incidence of FHB and severity of leaf‐spot in spring wheat can be minimized through early planting combined with adequate starter N application.
The Effect of Logging and Slash‐Burning on Soil Structure
Authors: Dyrness C. T. , Youngberg C. T.
Published: July 2010

The effects of logging and slash‐burning on soil structure were investigated on three Reddish Brown Latosol soils in the Coast Range of Western Oregon. Soil samples of the surface 2 inches were collected at 50‐foot intervals along randomly located transects within the clear‐cut areas. Soil samples were also collected in the adjacent uncut timber. The condition of the surface soil was noted at 10‐foot intervals along the transects and was recorded as follows: lightly burned, severely burned, disturbed and unburned, or undisturbed. Sixty soil samples from each clear‐cut sampling area were analyzed in the laboratory for mechanical composition, organic matter content, and water stable aggregates.

The soil surface conditions after logging and slash‐burning were as follows: lightly burned 44.7%, severely burned 8%, unburned 30.1%, and undisturbed 17.2%. Severe burning was the only treatment that had any significant effects upon soil structure, particle size distribution and soil organic matter content. Analysis of variance revealed that there was a significant decrease in the amount of clay present in the severely burned soils as compared with the soils under undisturbed timber. A 20.6% decrease in the degree of aggregation and a 61.1% decrease in organic matter content were also noted in the severely burned soils as compared with soils in the undisturbed timber. Other treatments had no significant effects upon the soils of the logged area.

Since only 8% of the soil surface was severely burned, it is concluded that logging by the high lead method and slash‐burning in the fall after rainfall has occurred have had no appreciable detrimental effects upon soil structure in the area studied.
Soil Nitrogen Complexes: II. Electrophoretic Separation of Organic Components
Authors: Waldron A. C. , Mortensen J. L.
Published: July 2010

Extracts of soil organic matter solubilized by 0.1M Na4P2O7 and hydrolyzed by 0.5N NaOH, 6N HCl, and 0.1M Na4P2O7 + 0.5N NaOH were electrically desalted and subjected to continuous flow paper electrophoresis. Determination of organic matter, total nitrogen, α‐amino nitrogen and amino sugar in the collection tubes revealed the presence of nitrogen‐containing components having different electrophoretic mobilities.

NaOH and HCl hydrolysates contained several nitrogenous components in which α‐amino nitrogen and amino sugars were detected. These hydrolysates also contained a brown‐colored component which contained most of the organic matter. The Na4P2O7 extract, which exhibited considerable loss of organic nitrogen during desalting, contained one major component in which most of the nitrogen and brown material was contained.

A fluorescent component was associated with the brown‐colored component in each extract.
A Glassbead‐Glycerol Model for Non‐Steady‐State Tile Drainage
Authors: Grover Ben L. , Kirkham Don
Published: July 2010

The construction and use of a reduced scale model for studying the falling water table in non‐steady‐state drainage problems are described. A capillary fringe is accounted for in the model. Stratified soils may be simulated. It is concluded that the model can be used to obtain information which is valuable in drainage theory and design.
Soil Moisture Evaluation by Tensiometers
Authors: Perrier Eugene R. , Evans D. D.
Published: July 2010

Four different types of tensiometers were compared and found to be quite similar within their range of measurement. Only a slight difference in range was found between the instruments.

Moisture desorption curves obtained by plotting tensiometer readings versus soil water content as obtained by sampling were different from those obtained by the porous plate apparatus using cores or disturbed samples. The differences are associated with structural changes resulting from the procesures used in the porous plate technique. The moisture desorption curves obtained with the tensiometers should be reliable if time lag and hysteresis effects are small.
The Effect of Sulfur on the Absorption and Utilization of Molybdenum by Peas
Authors: Reisenauer H. M.
Published: July 2010

An experiment including a factorial combination of 4 rates of S and 3 rates of Mo fertilization was conducted on a low‐S, low‐Mo soil to evaluate the effects of soil S level on the absorption and utilization of Mo by peas. The uptake of soil and fertilizer Mo was markedly reduced by applications of sulfate fertilizer. The higher rates of S fertilization also reduced the apparent efficiency of utilization of Mo by the plant. Higher plant Mo levels were required for maximum yield and N fixation as the SO4‐S content of the plant tissue was increased by S fertilization. Correlation coefficients of 0.78 and 0.94 were obtained with response surface equations for seed yield and vine N content as functions of the Mo and SO4‐S contents of the plant tissues. Maximum pea yields were associated with plant tissue Mo contents of 0.3 to 1.0 ppm. and 200 to 600 ppm. of SO4‐S.
Hydraulic Properties of a Clay Loam Soil and the Field Measurement of Water Uptake by Roots: I. Interpretation of Water Content and Pressure Profiles
Authors: van Bavel C. H. M. , Stirk G. B. , Brust K. J.
Published: July 2010

The distribution of irrigation water in an Adelanto clay loam profile was studied in a field plot by simultaneous, periodic observations of the water content and hydraulic head profiles. Successive measurement series were made with the plot bare and covered, bare, and planted to a sorghum crop (Sorghum vulgare Pers.). From the first two, the in situ and dynamic relations of water content to water pressure and to conductivity were obtained. From the cropped field data, the root‐extraction pattern was derived, using the established hydraulic properties of the profile. The data demonstrate the variability within depths and locations of water retention and conduction properties and the consequent problem of calculating fluxes. The mobile character of soil water is also evident, confirming the inadequacy of static concepts of soil water “constants” for a profile. Calculated root‐extraction rates agreed reasonably with independent lysimetric measurements of the water loss from the surface to the atmosphere.
Variation in the Relative Distribution of Amino Sugars with Depth in Some Soil Profiles
Authors: Stevenson F. J. , Braids O. C.
Published: July 2010

Ion exchange chromatography of the amino sugars in hydrolysates of several soil profiles revealed that the proportion of the amino sugar material in the form of glucosamine increased dramatically with increasing depth. Little variation was noted in the relative distribution of amino sugars in the surface horizons of the soils examined.
Convective Diffusion in Clay Systems
Authors: Overman Allen R.
Published: July 2010

The theory of convective diffusion has been applied to transport of salt through clay columns. An expression was derived for salt distribution within the column for steady state conditions.

Data from the literature were used to test the applicability of the distribution function to clay systems. The observed nonlinearity is described to high precision by the equation. However, some discrepancy occurs between calculated and measured parameters.
Movement of Water and Salt through a Clay‐Water System: Experimental Verification of Onsager Reciprocal Relation
Authors: Letey J. , Kemper W. D.
Published: July 2010

Equations that describe the movement of solution and salt through a soil system in which there are both hydrostatic and osmotic pressure gradients are presented. These equations are: JV = − LP ∇P + LPD ∇π, JD = LDP ∇P − LD ∇π, and JS/CS = (−LP + LDP) ∇P + (−LD + LPD) ∇π where JV is the flux of solution, JD the difference in velocity between water and salt, JS is flux of salt, P is pressure, π is osmotic pressure, CS is the average solute concentration, and L is phenomenological coefficients. The Onsager reciprocal relation states that LPD = LDP. This relation was found to be valid for a clay‐water‐salt system.
Specific Character of Boron Adsorption by an Amorphous Soil
Authors: Bingham Frank T. , Page A. L.
Published: July 2010

The adsorption of boron by an allophanic soil as influenced by the presence of sulfate, phosphate, and monosilicic acid was studied at pH 6.0 and 8.5. Amounts of B adsorbed by the soil from a 4.8 mM B solution which contained sulfate or phosphate ions in varying concentrations up to 0.1M were independent of the presence of these anions. Pretreatment of soil by repeated saturation with 1.42 mM Si solution resulted in a slight but progressive decrease in the quantity of B adsorbed subsequently from the 4.8 mM B solution. Apparently, B adsorption by allophanic soils is more or less specific, being essentially independent of the presence of other anions.
Effect of Urea Fertilization on Nitrification in Forest Soils of the Pacific Northwest
Authors: Heilman Paul
Published: July 2010

Nitrate levels in untreated samples of upper mineral soil from 14 Douglas‐fir (Pseudotsuga menziesii) and western hemlock (Tsuga heterophylla) sites incubated at 20C for 21 days varied from 0 to 45 ppm N. No relationship of nitrification to soil pH was evident but N and organic C content appeared to be associated with nitrate production; for nitrate versus total N, r = 0.85, and versus organic C, r = 0.75, while nitrate versus C:N ratio, r = −0.38. Little nitrate was produced in soils with C:N ratios above 27.

Treatment of the soils with urea at approximately 400 ppm N increased nitrate levels in similarly incubated samples by an average of 70 ppm N. The increases varied considerably with two soils still containing less than 4 ppm N as nitrate and four with over 100 ppm nitrate N (one exceeded 300 ppm N).

N fertilization in the field markedly increased capability of the majority of soils tested to form nitrate following subsequent urea treatment.

Low temperature (2.5 and 5C) restricted nitrification whether or not soils were treated with urea. Generally, rate of nitrification in urea‐treated soils increased rapidly with increase in temperature above 5C. The patterns of increase in nitrate with increase in temperature and time suggest that low nitrification capability in some soils results primarily from low population of nitrifying organisms and that nitrate levels following urea treatment are linked to growth of the population of nitrifying organisms in response to a large supply of ammoniacal N.
Steady Flows of Water and Salt in Uniform Soil Profiles with Plant Roots
Authors: Raats P. A. C.
Published: July 2010

Steady upward and downward flows of water in the presence of uptake of water by plant roots are analyzed. Qualitative features of possible pressure head, total head, and water content profiles for steady conditions are discussed. Specific calculations are based upon an exponential increase of the hydraulic conductivity with the pressure head and an exponential decrease of the rate of uptake with depth. For downward flows, the distribution of the matric flux potential can be expressed as a function of the rate of infiltration, the leaching fraction, and two parameters characterizing the soil and the uptake distribution, respectively. Although the water content in the root zone may be nearly uniform, the matric component of the flux may be significant. For upward flows, the distribution of the matric flux potential can be expressed as a function of the rate of infiltration, the rate of transpiration, the hydraulic conductivity of the saturated soil and the same two parameters characterizing the soil and the uptake distribution. The depth at which the flux vanishes, the minimum value of the matric flux potential for a given depth of the water table, and the maximum depth of the water table are evaluated. Finally, neglecting the effects of salt precipitation and dissolution and of diffusion and dispersion, the distribution of salts associated with the steady downward flows is evaluated.
Lysimeter and Field Measurements of Chloride and Bromide Leaching in an Uncultivated Loamy Sand
Authors: Saffigna P. G. , Keeney D. R. , Tanner C. B.
Published: July 2010

Field and lysimeter measurements were made of Cl and Br leaching in a Plainfield loamy sand at Hancock, Wisconsin. Chloride and Br were excellent companion tracers, moving in a 1:1 ratio through the 500‐cm field profile to the water table even when large differences in halide leaching occurred between adjacent sites. Half of the Cl or Br applied to the lysimeters was leached through the 125‐cm lysimeter profile in 13 or 17 cm of drainage during 22‐ and 205‐day experiments, respectively. Edge effects in the lysimeter were studied by applying Br near the edge and Cl in the center. Bromide was detected in the lysimeter drainage before Cl, but overall, edge effects were small.

Lateral movement of Cl and Br in the lysimeter profile was < 20 cm. This helps explain why large localized variations in solute transport can persist to considerable depth in this sandy soil. The differences in the distribution of halide between adjacent soil profiles within the lysimeter and field exceeded the average differences between the field and the lysimeter soil profiles.
Decomposition in Soil of 14C‐labeled Coumaryl Alcohols; Free and Linked into Dehydropolymer and Plant Lignins and Model Humic Acids
Authors: Haider K. , Martin J. P. , Rietz E.
Published: July 2010

Side chain and ring‐14C‐labeled coumaryl alcohols and coumaric acids and ring‐14C‐labeled ferulic, caffeic, protocatechuic, vanillic, and p‐hydroxybenzoic acids and coniferyl alcohol were synthesized. The coumaryl alcohols and phenolic acids were linked into model phenolase humic polymers. Labeled corn (Zea mays L.) stalk lignins were prepared by injecting the labeled coumaric acids as lignin precursors into growing corn plants. Model DHP lignins were prepared by polymerizing the labeled coumaryl alcohols with unlabeled coniferyl alcohol using peroxidase and hydrogen peroxide. Decomposition of the labeled carbons in the phenolic compounds and in the polymers was followed in a neutral sandy loam soil. After a 28‐week incubation period about 58, 44, and 47% of the CH2OH and 2‐(side chain) and ring‐14carbons, respectively, of applied coumaryl alcohols had evolved as 14CO2. Losses of ring C from other common benzenoid compounds ranged from 68 to 84%. Linkage of coumaryl alcohols into model humic acids reduced losses of ring carbons to 5 to 12%. The decomposition percentages for the CH2OH and 2‐(side chain) and ring‐14carbons of the coumaryl alcohols linked into model lignins were 33, 18, and 20%, respectively, while comparable values for the same carbons in corn stalk lignins averaged 7% higher. About 40 to 60% of the residual 14C activity from the lignins and model polymers was recovered in the humic acid fraction of the soil. The amounts of coumaryl alcohol and other phenolic compounds linking into model phenolase polymers were inversely related to the degradability of the compounds in soil.