bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of the Root Zone Water Quality Model Using Field‐Measured Data from the Missouri MSEA
Authors: Ghidey Fessehaie , Alberts E. Eugene , Kitchen Newell R.
Published: July 2010

The USDA‐ARS Root Zone Water Quality Model (RZWQM) is a comprehensive computer model developed to simulate water, chemical, and biological processes in the root zone of agricultural management systems. The model is capable of evaluating the effects of various cropping and management practices on surface and ground water quality. In this study, the performance of RZWQM Version 3.2 was evaluated for a claypan soil, particularly surface runoff and chemical loss to surface runoff predictions. The model was calibrated and evaluated using data collected from the Missouri Management Systems Evaluation Area (MSEA) and the Kingdom City runoff plots. Soil water predictions of the model compared well with those measured, particularly at the 15−, 60−, 75−, and 90−cm soil depths. In most cases, corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] yield predictions were within 15 and 20%, respectively, of those measured. Using the macropore option (constant cracking) greatly improved the prediction of chemical losses to seepage. Annual runoff simulated for corn and soybean under conventional and no‐till systems was adequately predicted. The model underpredicted large runoff events and overpredicted runoff events that occurred after long dry periods when soil cracking was a dominant factor. The model overpredicted NO3−N concentrations in runoff but underpredicted concentrations in near‐surface soils. Predicted and measured atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] and alachlor [2‐chloro‐N‐(2,6‐diethylphenyl)‐N‐(methoxymethyl)acetamide) concentrations in surface runoff compared well, particularly when the computed runoff was close to that measured. In this study, the model was run using the option of constant cracking in the soil. To improve the predictions of agrichemical losses to runoff and seepage, RZWQM should include the capability to predict variable soil cracking based on soil moisture.
Nitrogen‐15 Labeling of Dairy Feces and Urine for Nutrient Cycling Studies
Authors: Powell J. Mark , Wu Zhiguo
Published: July 2010

Estimates of the availability of dairy manure nutrients to crops rely on indirect measurements and can vary greatly. More accurate estimates of manure nutrient availability are needed to improve manure management. The objective of this study was to enrich dairy feces and urine in 15N to study nutrient flow in the feed–animal–manure–soil and crop–environment continuum. Ammonium sulfate (12.3 or 10 atom % 15N) was applied to soil to enrich alfalfa (Medicago sativa L.) and corn (Zea mays L.) plants during growth. Alfalfa hay contained from 2.386 to 3.980 atom % 15N in three harvests and corn silage contained 8.162 atom % 15N. A feed mixture containing 55% alfalfa hay and 45% corn silage (4.026 atom % 15N) was fed to two mature nonlactating cows (Bos taurus) for 36 h. The pattern of 15N excretion in urine and feces was similar for both cows. The 15N appeared in urine by 8 h and in feces by 24 h, and peaked by 30 h in urine (1.642 atom % 15N) and by 54 h in feces (2.341 atom % 15N). Enrichment approached basal levels at 132 h after initial feeding for both urine and feces. Of the total 15N fed, 60% was recovered: 31% from urine and 29% from feces. Approximately 60 to 70% of the total N excreted in dairy feces was endogenous N and 30 to 40% was undigested feed N. Combining feces excreted during the 16‐ to 122‐h period after initial feeding of 15N‐enriched feed would produce feces having uniformly labeled N components. The various 15N‐enrichment levels of urine and feces collected during different times after feeding offer possibilities for studying differential 15N use in short‐ and long‐term nutrient cycling studies.
Soybean Yield and Nutrient Composition as Affected by Early Season Foliar Fertilization
Authors: Haq Mazhar U. , Mallarino Antonio P.
Published: July 2010

The response of soybean [Glycine max (L.) Merr.] to foliar fertilization during early growth stages has received little attention. Recent Iowa research showed a 15% probability of positive yield response to a 3–15–8 (N–P–K) fertilizer applied at the V5 growth stage. This study evaluated the effects of fertilizers varying in N–P–K ratio on soybean grain yield and tissue nutrient composition. Twenty‐seven field trials were conducted in soils that tested at or above optimum soil P and K levels for soybean. Six treatments included a control and nonfactorial combinations of rates and application frequency of 28 to 56 L ha−1 of 3–8–15, 10–4–8, and 8–0–7 fertilizers sprayed at the V5 stage. Differences between treatments were inconsistent across sites. Some or all treatments increased or decreased yields significantly at six sites. The mean yield increase or decrease for responsive sites was 400 kg ha−1. The 3–8–15 fertilizer caused no leaf damage and other fertilizers caused little or no damage, although the damage was not clearly related with yield decreases. Analyses by site showed that fertilization seldom increased tissue N–P–K composition, nutrient uptake, photosynthesis, or plant weight measured at the R2 growth stage. Multivariate analyses across sites showed that 27% of the variation in yield response was explained by a combination of N, P, and K availability, vegetative growth, and rainfall. Positive yield responses tended to occur when soil or weather conditions reduced plant growth and nutrient availability. Foliar fertilization across all conditions will not offset the application costs.
Grain Yield, Early Growth, and Nutrient Uptake of No‐Till Soybean as Affected by Phosphorus and Potassium Placement
Authors: Borges Rogerio , Mallarino Antonio P.
Published: July 2010

More information is needed about P and K placement for no‐till soybean [Glycine max (L.) Merr.]. This study evaluated plant responses to P and K fertilization and placement in 10 long‐term trials and 11 short‐term trials in Iowa from 1994 to 1997. Treatments were various P and K rates broadcast, banded with the planter, and deep banded (at a 15‐ to 20‐cm depth). Measurements were plant weight, P uptake, and K uptake at the V5 stage and grain yield. Phosphorus fertilization increased yield when soil‐test P (STP) was less than 9 mg P kg−1 (Bray‐P1) at a 0‐ to 15‐cm depth or 12 mg P kg−1 at a 0‐ to 7.5‐cm depth. The P placement did not influence yield. The band K placements produced slightly higher yield than the broadcast placement. Responses to K were not related to soil‐test K (STK) levels, which varied from 90 to 262 mg K kg−1 (ammonium acetate), or stratification. The P or K placement had little influence on early growth but influenced early P and K uptake. Banding with the planter was more effective than broadcasting for P uptake, and the two band placements were more effective for K uptake. Only the responses of K uptake and grain yield to banded K were correlated across sites. A shallow sampling depth will improve only slightly the prediction of response to P. The observed small no‐till soybean yield response to banded K would seldom offset increased application costs in similar soils.
Yield and Quality of Banana Irrigated with Fractions of Class A Pan Evaporation on an Oxisol
Authors: Goenaga Ricardo , Irizarry Heber
Published: July 2010

There is a scarcity of information regarding the optimum water requirement for banana (Musa acuminata Colla, AAA group) grown with supplemental drip irrigation on an Oxisol. A 3‐yr study was conducted on a very‐fine, kaolinitic, isohyperthermic Typic Hapludox to determine water requirement, yield, and fruit‐quality traits of the plant crop (PC) and two ratoon crops (R2 and R3) of ‘Grande Naine’ and ‘Johnson’ banana subjected to five levels of irrigation. The irrigation treatments were based on Class A pan factors that ranged from 0.25 to 1.25 in increments of 0.25. Drip irrigation was supplied three times a week on alternate days. Results showed significant (P < 0.001) irrigation treatment and crop effects for all yield components, fruit length and diameter, number of leaves at flowering and harvest, and number of hands per bunch. Cultivar and the treatment by cultivar interaction were not significant (P < 0.05). The highest marketable yield (70.7 Mg ha−1) was obtained from the R2 crop with water application according to a pan factor of 1.25. Plant crop and R3 plants irrigated using the same pan factor yielded 48 and 65 Mg ha−1, respectively. Increasing the pan factors from 0.25 to 1.25 resulted in weight gains of the third‐upper hand of 594 g in PC, 1284 g in R2, and 1429 g in R3. It was concluded that banana grown on an Oxisol should be drip irrigated with a pan factor of 1.0 or more three times a week.
Sequential Cropping as a Function of Water in a Seasonal Tropical Region
Authors: Radulovich Ricardo
Published: July 2010

In the seasonal (wet–dry) tropics, yields of rainfed staple crops are usually low and variable. However, our simulations have indicated that rainfall could be used more efficiently, increasing the length of the rainfed cropping season, the number of crops grown, and their yields, while decreasing yield variability and risk. To evaluate these predictions, cropping schemes with two or three annual rainfed crops grown in sequence were field‐tested. Irrigated plantings were subsequently added to evaluate year‐round cropping. Work was conducted in Costa Rica during 4 yr at one site and 1 yr at a second site. Both sites have a half‐year‐long, bimodal rainy season, and have deep soils with high water‐holding capacity. The first crop of each year was planted early using preseason rains, and the last was planted to mature after the rainy season to maximize depletion of available soil water. Rainfed cropping sequences averaged 255 d long, which is from 50 to 100 d longer than local practices. Adding an irrigated planting during the dry season brought the mean length of the cropping season up to 346 d. Of 115 plantings, only 7 had low yields; all others had medium or high yields. Adding an irrigated crop increased yield potential of a year‐round cropping season composed of two or more plantings. All low yields were attributed here to extended water excess conditions. However, water excess effects do not remain after the rainy season, nor into the next rainy season.
Analysis of Grain‐Yield Components and Inflorescence Levels in Winter‐Type White Lupin
Authors: Noffsinger Steven L. , Huyghe Christian , van Santen Edzard
Published: July 2010

In winter‐type white lupin (Lupinus albus L.), an improved understanding of the importance of inflorescence levels and yield components among environments could be useful when considering selection criteria for breeding. We examined inflorescence levels and yield components of indeterminate, determinate, and dwarf accessions among a broad range of environments. Data were acquired from date‐of‐seeding (DOS) and dry matter partitioning (DMP) studies. The DOS studies were conducted from 1991 to 1993 in north, central, and south Alabama, USA. The DMP studies were conducted for 2 yr in western France and central Alabama. We used principal‐component analysis to reduce the number of yield components for further consideration in future breeding. The first four principal components had Eigenvalues >1 and contributed ≥74% of the variance. Pod number m−2, seed number m−2, pod yield m−2, and seed yield m−2 were highly correlated (r ≥0.80, P ≤0.01) with most principal components. The first two to four principal components also had biological meaning because yield components that were highly correlated with each principal component were associated with a specific inflorescence level. Mainstem and primary‐branch inflorescence levels were most important for yield and yield‐component development. Basal branches were important in the southeastern USA, but these inflorescence levels should be selected against in France. Pod number m−2 and seed weight had the greatest effect on grain yield. Breeding for higher seed weight will improve cold tolerance and stabilize grain yield in western France, but further testing is needed in Alabama. Selecting germplasm with low pod abortion will help increase pod number potential.
Determination of Crop Water Stress Index for Irrigation Timing and Yield Estimation of Corn
Authors: Irmak Suat , Haman Dorota Z. , Bastug Ruhi
Published: July 2010

Corn (Zea mays L.) grown under a Mediterranean semiarid climate requires supplemental irrigation to maximize the grain yield. Since the cost of irrigation application has been increasing, elimination of unnecessary irrigation applications would improve economics of corn production. There has been much interest in the crop water stress index (CWSI) as a potential tool for irrigation scheduling and yield estimation. An experiment was conducted to monitor and quantify water stress, and to develop parameters for irrigation scheduling and grain yield of summer‐grown corn as a function of CWSI under Mediterranean semiarid cropping conditions. Three irrigation treatments were based on replenishing the 0.9‐m deep root zone to field capacity when the soil water level dropped to 25, 50, and 75% of available water holding capacity (AWHC). A dryland treatment was also included. The lower (nonstressed) and upper (stressed) baselines were measured to calculate CWSI. An equation that can be used to calculate the yield potential of summer‐grown corn under a Mediterranean climate was developed using the relationship between the corn grain yield and the seasonal mean CWSI. Permitting the seasonal average CWSI value to exceed more than 0.22 resulted in decreased corn grain yield. The CWSI behaved as expected, dropping to near zero following an irrigation and increasing gradually as corn plants depleted soil water reserves. We concluded that CWSI is a useful tool to monitor and quantify the water stress of corn under a Mediterranean climate.
Establishment of Irrigated Timothy for Forage Production in Saskatchewan
Authors: Jefferson Paul G. , Coulman Bruce E. , Kielly G. Andrew
Published: July 2010

Irrigated timothy (Phleum pratense L.) hay from Saskatchewan could fill export demand for compressed hay, but basic agronomic information is lacking under Saskatchewan conditions. The objective of this research was to compare the establishment of irrigated timothy seedlings under wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), and Italian ryegrass (Lolium multiflorum Lam.) companion crops at two seeding rates. The ryegrass companion crop reduced timothy ground cover and tiller density in the year after establishment, with a greater reduction in ground cover at 10 kg ha−1 compared with a seeding rate of 5 kg ha−1 for the ryegrass. The ryegrass companion crop reduced timothy first harvest and total annual dry matter (DM) production for forage by 41% compared with the control (no companion crop) while timothy that was established with cereal companion crops did not differ from the control. Irrigated forage producers should not use annual ryegrass as a companion crop for irrigated timothy establishment in Saskatchewan.
Estimating Forage Mass with a Commercial Capacitance Meter, Rising Plate Meter, and Pasture Ruler
Authors: Sanderson Matt A. , Rotz C. Alan , Fultz Stanley W. , Rayburn Edward B.
Published: July 2010

Accurate assessment of forage mass in pastures is key to budgeting forage in grazing systems. Our objective was to determine the accuracy of an electronic capacitance meter, a rising plate meter, and a pasture ruler in measuring forage mass and to determine the cost of measurement inaccuracy. Forage mass was estimated in grazed pastures on farms in Pennsylvania, Maryland, and West Virginia in 1998 and 1999. Forage mass estimated by each method was compared with forage mass estimated by hand‐clipped samples. None of these indirect methods were accurate or precise, and error levels ranged from 26 to 33% of the mean forage mass measured on the pastures. The computer model DAFOSYM (Dairy Forage System Model) was used to simulate farm performance and the resulting effects of inaccuracies in estimating forage mass on pasture. A representative grazing dairy farm was developed, and the costs and returns from low‐input and conventional managements were calculated. Different scenarios were then simulated, including under‐ or overestimating forage yield on pastures by 10 or 20%. All scenarios simulated resulted in lower returns compared with the optimum farm, with decreases in net return ranging from $8 to $198 ha−1 yr−1. Underestimating forage mass resulted in less hay and silage being harvested, more pasture being consumed, and more forage purchased compared with the optimum scenario. The opposite occurred for overestimation of forage mass. Our results indicate that achieving greater accuracy (to within 10% of actual pasture yield) in estimating pasture yields will improve forage budgeting and increase net returns.
Allelopathic Potential of White Top and Syrian Sage on Vegetable Crops
Authors: Qasem Jamal R.
Published: July 2010

White top [Cardaria draba (L.) Desv.] and Syrian sage (Salvia syriaca L.) are noxious common weeds of field crops and orchards in Jordan. This study was conducted to investigate any allelopathic potential of volatiles, foliage leachates, root exudates, and shoot dried residues of both weed species on cabbage (Brassica oleracea L. var. Capitata cv. Pronzwik), carrot (Daucus carota L. cv. Natus), cucumber (Cucumis sativus L. cv. Beithalpha), squash (Cucurbita pepo L. cv. Byrouti), onion (Allium cepa L. cv. Texas Early Grana), pepper (Capsicum annum L. cv. Red Common), or tomato (Lycopersicon esculentum Mill cv. Special Back) through different laboratory and glasshouse experiments. Volatiles from Syrian sage fresh shoots reduced germination and inhibited seedling growth of most crops, and foliage leachates or root exudates of both weeds were toxic to different crops under laboratory conditions, with most effects on tomato and cabbage. In pot experiments, surface‐placed shoot residues of both weeds significantly delayed seed germination and reduced seedling growth of all crops with carrot, onion, and tomato being the most affected. Decayed residues of white top were also toxic at 32 g kg−1, but lower toxicity was obtained than when fresh materials were used. Foliage leachates or root exudates of both weed species added or released into the soil mixture reduced seedling growth of cabbage and tomato. Results showed that white top and Syrian sage are of great allelopathic potential against different vegetable crops; cabbage, onion, and tomato being the most sensitive crops.
Downsizing an Integrated Crop Management Field Study Affects Economic and Biological Results
Authors: Wei Wei , Alldredge J. Richard , Young Douglas L. , Young Frank L.
Published: July 2010

In recent years, there has been increased interest in long‐term, field‐scale cropping systems research to improve pest management, to protect air and soil quality, and to increase or maintain growers’ profits. However, these studies require large tracts of land, sizeable labor forces, and substantial inventories of equipment, which make them very expensive to conduct. Because of recent concerns about reducing field research costs, this study compares economic and biological results from an original complete 6‐yr integrated cropping management (ICM) systems field study to results from several downsized experiments, which were components of the complete study. Compared with the original ICM study, the downsized experiments reduced the number of treatment replications from four to three, reduced the number of crop rotation cycles from two to one (from 6 to 3 yr), or only grew one crop per rotation each year. The effect of downsizing on the profitability analysis and the statistical (biological) analysis were similar. Reducing replications altered both profitability and biological conclusions less than reducing the number of rotation cycles. Reducing crop rotation cycles markedly altered treatment profitability rankings compared with the complete study. Growing only one crop in a rotation per year was the most detrimental to biological results and entirely precluded computing mean annual cropping system profitability. This empirical study supports the importance of replicating treatments fully over time, over space, and over crop rotational positions.
Interseeding Kura Clover and Birdsfoot Trefoil into Existing Cool‐Season Grass Pastures
Authors: Cuomo Gregory J. , Johnson Dennis G. , Head William A.
Published: July 2010

Legumes in cool‐season grass pastures can improve productivity and quality. In May of 1997 and 1998, a split‐split plot field experiment with six replications was planted in Morris, MN to evaluate the effect of sod suppression, planting method, and legume species on establishment of legumes into existing cool‐season grass pastures and to evaluate kura clover (Trifolium ambiguum Bieb.) and birdsfoot trefoil (Lotus corniculatus L.) as potential species for interseeding in the North Central region. Whole‐plot sod suppression treatments were (i) 0.62 kg a.i. ha−1 glyphosate [isopropylamine of N‐(phosphono‐methyl) glycine] or (ii) no glyphosate. Subplot planting methods were (i) no‐till drilling, (ii) broadcasting seed on the soil, (iii) broadcasting seed followed by harrowing, and (iv) broadcasting seed followed by a light disking. Legume species sub‐subplots were (i) alfalfa (Medicago sativa L.), (ii) red clover (Trifolium pratense L.), (iii) kura clover, and (iv) birdsfoot trefoil. Stand data were collected in the fall of the planting year and in the spring of the second growing season. Averaged across planting methods and species, legume stands were 38% where glyphosate was used and 3% where it was not. No differences or interactions were detected for planting method (P > 0.12). In this study, if competing vegetation was suppressed, stands were >31% regardless of planting method. When sod was suppressed, alfalfa established better stands than the other legume species. The overriding factor in the ability to establish legumes in this study was the suppression of existing vegetation during establishment.
Field Drying of TopCross High‐Oil Corn Grain
Authors: Thomison Peter R. , Geyer Allen B. , Bishop Bert L.
Published: July 2010

Most high‐oil (HO) corn (Zea mays L.) grown in the USA utilizes the TopCross system, which involves planting a blend (TC Blend) of two types of corn. Field grain drying of TC Blends may be slower than normal (low oil) corn hybrids of similar maturity, which could result in later harvest or increased costs of artificial drying after harvest. The objective of this study was to determine whether HO grain produced by TC Blends dries to moisture percentages typically associated with corn harvests on the same calendar dates as normal corn grain. Field drying of corn grain was followed in five TC Blends and their normal counterparts (check hybrids) grown in strip plots established at multiple locations in central Ohio in 1995 and 1996. Moisture measurements of grain from HO and check hybrids during field drying and at harvest were determined using the USDA approved air‐oven drying method, commercial electronic moisture testers, or both. Differences in field grain drying and grain moisture at harvest between the TC Blends and their respective check hybrids were generally small and not significant (P = 0.05), with only one of the five pairs showing large differences each year. Differences in grain drying were greater in 1995 than in 1996, suggesting that environmental conditions may influence differences in the time required for HO and check hybrid grain to reach harvest moisture levels. Results of this study indicate that HO corn can be produced without additional grain‐drying costs.
Plant Growth Regulator Effects on Spring Cereal Root and Shoot Growth
Authors: Rajala A. , Peltonen‐Sainio P.
Published: July 2010

Plant growth regulators (PGR) shorten the straw of cereals, but their effects on other traits of plant stand structure have been inconsistent. To arrive at an assessment of whole‐plant response, experiments were conducted in the greenhouse to study the effect of PGR applications on root and shoot growth of spring cereals. Ethephon, chlormequat chloride (CCC), and trinexapac–ethyl were applied during early growth stages to barley (Hordeum vulgare L.), oat (Avena sativa L.), and wheat (Triticum aestivum L.) cultivars grown either in sand mixture or in clay illitic topsoil. The effects on root and shoot growth (mg plant−1), root/shoot ratio, tiller number, and weight per main shoot were studied in all cereal species. The response of CO2 exchange rate (CER) (μmol CO2 m−2 s−1) and formation of yield potential to PGR treatment were studied more closely in “Mahti” wheat. The effect of CCC application on root area (cm2), length (cm), specific root length (SRL cm/mg), and width (μm) at soil depths of 0 to 20, 20 to 40, and 40 to 60 cm was studied in Mahti wheat. Plant growth regulator applications reduced main shoot growth in barley and wheat up to 20%. Tiller production was enhanced by ethephon and TE treatment in all species, but not adequately to compensate for PGR‐induced reduction in main shoot growth. Carbon dioxide exchange rate was reduced temporarily by ethephon and TE treatments in Mahti wheat. Plant growth regulator applications have modest potential for modifying traits of spring cereal plant stand structure other than straw length.
Soil Conditioner Effects on Runoff and Potato Yield under Sprinkler Irrigation
Authors: Ben‐Hur Meni
Published: July 2010

Synthetic polymers can be used as soil conditioners, but studies of their effects have addressed laboratory simulations much more than cultivated fields. The objective of this work was to study the effects of a low‐molecular‐weight, nonionic polymer (P‐1O1) on seal formation, infiltration rate (IR), runoff, erosion, and potato (Solanum tuberosum L.) yield. The experiment comprised (i) a laboratory rainfall simulator study and (ii) irrigation of a field in the Negev, Israel with a moving sprinkler irrigation system (MSIS) fitted with various emitters. The emitters were Sprayer No. 1, Spinner, and Super Spray, with discharges of 1254, 2713, and 1777 L h−1, respectively. The studied soil was Calcic Haploxeralf. Under simulated rain, polymer applications of 50, 25, 10, 5, and 0 (control) kg ha−1 resulted in final IR values of 31, 28, 27, 19, and 17 mm h−1, respectively, and erosion rates of 0.9, 0.9, 1.9, 3.5, and 6.1 t ha−1, respectively. In the field, the 40 kg ha−1 polymer treatment, applied with Sprayer No. 1, Spinner, and Super Spray emitters, reduced runoff by 75, 60, and 62%, respectively, compared with the control treatment. The irrigation efficiencies (the ratios between plant yield and total water application) of the MSIS with Sprayer No. 1, Spinner, and Super spray were 56, 31, and 43 kg mm−1, respectively, on untreated soil and 66, 49, and 65 kg mm−1, respectively, under the 40 kg ha−1 polymer treatment.
Implications of Repeated Trinexapac‐Ethyl Applications on Kentucky Bluegrass
Authors: Lickfeldt Darin W. , Gardner David S. , Branham Bruce E. , Voigt Thomas B.
Published: July 2010

Reducing turfgrass clipping production is often the goal of managers who recognize the need to save time, money, or landfill space. The objective of this study was to investigate the long‐term implications of repeated trinexapac‐ethyl [4‐(cyclopropyl‐α‐hydroxy‐methylene)‐3, 5‐dioxocyclohexanecarboxylic acid ethyl ester] applications at two fertility levels (150 and 300 kg N ha−1 yr−1) on Kentucky bluegrass (Poa pratensis L.). Trinexapac‐ethyl (TE) was applied at 0.17, 0.23, or 0.29 kg a.i. ha−1 every 4 wk or at 0.23, 0.29, or 0.34 kg a.i. ha−1 every 6 wk for three growing seasons. Clippings were reduced by 22 to 41% when TE was applied every 4 wk (five applications per season) from May through August, and turfgrass quality was improved. A 6‐wk application schedule (four applications per season) did not reduce clipping production as consistently as the 4‐wk application schedule due to a postsuppression rebound effect Nitrogen fertility above 150 kg N ha−1 yr−1 was not necessary to maintain excellent turfgrass quality. Turf treated with TE consistently displayed better visual quality than untreated turf regardless of the TE application rate. Repeated applications of TE resulted in less dollar spot disease (Sclerotinia homeocarpa F.T. Bennett). Applications of TE not only reduced Kentucky bluegrass clipping production but were also effective in managing turfgrass growth. The postsuppression rebound effect can be utilized to manipulate turfgrass growth, allowing the turf to grow rapidly when it is beneficial to do so. No deleterious implications were observed following repeated TE applications.
Soil‐Sampling Alternatives and Variable‐Rate Liming for a Soybean–Corn Rotation
Authors: Bianchini Agustin A. , Mallarino Antonio P.
Published: July 2010

Precision agriculture technologies can be used to manage soil pH. This study compared soil‐sampling schemes for pH and evaluated variable‐rate (VR) liming for soybean [Glycine max (L.) Merr.] and corn (Zea mays L.). Global positioning systems and yield monitors were used in two fields. Soils were Typic Hapludolls, Aquic Hapludolls, and Typic Endoaquolls. Treatments were a control and a fixed‐rate (FR) or VR liming based on a 0.2‐ha soil‐sampling scheme. Soil pH (15‐cm depth) ranged from 5.4 to 8.4, and most subsoils were calcareous. Treatments were applied before soybean to long and replicated strips. Grain yield and soil pH were measured during 3 yr in one field and 2 yr in the other. Initial pH; canopy photos; and soil survey, elevation, and electrical‐conductivity maps were used to simulate sampling schemes based on larger cells or zones. Liming increased (P ≤ 0.05) corn yield in one site‐year (230 kg ha−1), and liming methods did not differ. The VR method applied less lime (56–61%) and reduced pH variability in one field. The lack of response was explained by high subsoil pH and high small‐scale variation of topsoil pH. Sampling schemes based on 0.7‐ha cells or zones identified smaller acid and alkaline areas than schemes based on small cells. Results suggest that yield response from lime is not likely when calcareous subsoils are present and topsoil pH is as low as 5.5. A VR liming method would apply less lime than a FR method in soils similar to those in this study.
Intercropping Irrigated Corn with Annual Legumes for Fall Forage in the High Plains
Authors: Alford Craig M. , Krall James M. , Miller Stephen D.
Published: July 2010

Many farmers in the central High Plains graze corn (Zea mays L.) aftermath and are looking at ways to improve the quality and amount of this fall pasture resource. However, no information is available on intercropping annual legumes with irrigated corn in the region. Our objective was to determine the most appropriate pasture legume species that could be used for an irrigated corn–legume system. To accomplish this, field experiments were conducted under irrigation at four sites in Wyoming. Eight legume species planted with corn were compared with monoculture corn under weed‐free and weedy conditions. Under weed‐free conditions, corn grain yields were reduced by the presence of legume in some treatments while others were comparable to the check yields. Black medic (Medicago lupulina L.) did not reduce corn yields, but barrel medic (M. truncatula Gaertn.) and sphere medic (M. sphaerocarpus L.) reduced corn yields by 17%. Corn yields were reduced 62% by the presence of weeds regardless of legume species. Legumes did not suppress weed growth. Barrel medic produced the most forage in July; however, there was little difference among species by November. In November, when corn stalks would be grazed, black medic and yellow sweetclover (Melitotus officinalis Lam.) produced the highest quality forage. These results indicate that a mostly weed‐free field is required to maximize corn and legume production. Of the legume species evaluated, black medic appears to offer the greatest potential for intercropping with irrigated corn in the central High Plains.
Comparison of Tillage Types and Frequencies for Cotton on Southern Piedmont Soil
Authors: Schomberg Harry H. , Langdale George W. , Franzluebbers Alan J. , Lamb Marshall C.
Published: July 2010

Tillage to disrupt root‐restricting, consolidated soil zones can improve rooting capacity and crop production, but costs increase with the need for more powerful tractors. Between 1992 and 1996, agronomic and economic consequences of annual or less frequent soil disruption treatments were evaluated for cotton (Gossypium hirsutum L.) on a Typic Kanhapludult. Two soil‐disruptive treatments, fall paratillage (PT) and in‐row chisel (IC) at planting (spring), were compared with two shallow‐tillage treatments, coulter planting plus weed control with sweeps (ST) and conventional disk tillage (DT). The IC, PT, and ST treatments were applied annually or in Years 3, 4, and 5. Lint yield with annual IC was 15 to 20% greater than with DT each year. In 1994, yields ranged from 0.53 to 0.84 Mg ha−1 with annual IC and were better than with annual ST or PT. In 1995, yields ranged from 0.92 to 1.29 Mg ha−1, with the top yield associated with current‐year IC application. In 1996, no differences in yield were observed among tillages; however, yields of two IC treatments were among the top five. For Years 3, 4, and 5, cotton yields were numerically greater with annual IC than with annual PT and ST. Yields with PT, ST, and DT were not different. Average annual net returns from annual IC were $450, $403, and $287 ha−1 greater than those with annual DT, PT, and ST, respectively. In‐row chisel appears to be a more economically viable production practice for heavy Piedmont soils compared with PT, ST, and DT.
The Model‐Document‐View Architecture and Its Application in Visual Rice Growth Model
Authors: Mi Xiangcheng , Zou Yingbin , Wei Wei
Published: July 2010

The object‐oriented paradigm (OOP) provides a methodology for resolving a crop simulation system into subsystems and processes so that a modeler can design objects to simulate their behaviors. Many objects are also devoted to producing object‐oriented user interfaces to simplify operation of the simulator. How to integrate these objects on a higher level and how to make models and user interfaces communicate efficiently are the issues addressed in the current research. The proposed model‐document‐view (MDV) architecture provides the modeler with an extension of OOP programming in crop modeling and a flexible scheme of system management and efficient data communication between simulator and user interface. The main advantage of the MDV architecture is that it separates the domain model, data management, and user interface but allows them to communicate efficiently. By using this architecture, the whole crop modeling system can also be integrated into several MDV groups. The system structure is clear and easy to administer, and communication between objects is more efficient. Here we report our experience with MDV architecture in constructing a rice (Oryza sativa L.) model called Visual Rice Growth Model (VRGM). The objects in VRGM were clustered into three MDV groups. The MDV paradigm was shown to meet the requirements of massive data management and displaying in a crop modeling system. The architecture can be used in any modeling system based on OOP.
Peanut Response to Planting Pattern, Row Spacing, and Irrigation
Authors: Lanier James E. , Jordan David L. , Spears Janet F. , Wells Randy , Johnson P. Dewayne , Barnes J. Steven , Hurt Christie A. , Brandenburg Rick L. , Bailey Jack E.
Published: July 2010

Experiments were conducted from 1999 through 2002 in North Carolina to compare interactions of planting pattern, plant population, and irrigation on peanut (Arachis hypogaea L.) pod yield and market grade characteristics. In additional experiments, pod yield and severity of tomato spotted wilt tospovirus associated with the cultivars NC‐V 11, NC 12C, VA 98R, and Perry were compared in single row (rows spaced 91 cm apart) and standard twin row (two rows spaced 18 cm apart on 91‐cm centers) planting patterns when peanut was dug and vines inverted on two digging dates spaced 10 to 16 d apart. In a third set of experiments, pod yield, market grade characteristics, and severity of tomato spotted wilt tospovirus were compared when the cultivars NC‐V 11 and Perry were planted in single row, standard twin row, and narrow twin row (two rows spaced 18 cm apart on 46‐cm centers) planting patterns. Peanut pod yield was higher in standard twin row planting patterns than when grown in single row planting patterns in some but not all experiments. Planting peanut in the narrow twin row pattern did not increase peanut pod yield over the standard twin row planting pattern. Less tomato spotted wilt was observed in standard or narrow twin row planting patterns compared with single row planting patterns. Planting peanut in single rows spaced 46 cm apart did not improve yield over peanut planted in single rows spaced 91 cm apart or the standard twin row planting pattern, regardless of irrigation treatment.
Residue Decomposition and Nutrient Release Dynamics from Two Tropical Forage Legumes in a Kenyan Environment
Authors: Njunie M. N. , Wagger M. G. , Luna‐Orea P.
Published: July 2010

Soil fertility decline is one of the factors limiting food production on the east coast of Africa. Increased awareness by smallholder farmers of the role of legumes as sources of food and fodder and for soil fertility improvement has stimulated research on the influence of herbaceous legumes in various cropping systems. Decomposition and nutrient release from foliage of legume species clitoria (Clitoria ternatea L.) and dolichos (Lablab purpureus L.) planted in monoculture and as an intercrop with tropical food crops cassava (Manihot esculenta Crantz) and maize (Zea mays L.) were evaluated under field conditions in fine‐loamy, kaolinitic, isohyperthermic, arenic Paleustalfs. The nylon mesh bag technique was used to obtain data to calculate the residue decomposition and nutrient release rates of the clitoria foliage cut every 6 or 10 wk and dolichos foliage cut at 2 or 4 mo. Asymptotic models provided the best fit for both dry matter decomposition and nutrient release. Legume residue decomposition rates (k) were unaffected by cropping system, with values of 0.2 and 0.5 wk−1 for clitoria and dolichos, respectively. Across cutting management strategies, the general order of nutrient release for clitoria at 6 or 10 wk was K > P > Mg > N; while that of dolichos was K > Mg > P > N and K > P > Mg > N for cuts at 2 and 4 mo, respectively. Overall, the residue N, P, and Mg release curves became asymptotic shortly after 60% of the nutrients had been released. Clitoria and dolichos showed their potential to become sources of nutrients for associated crops while protecting the soil surface.
Simplified Nitrogen Assessment of Orchardgrass Swards
Authors: Duru M.
Published: July 2010

A sward N index (Ni) based on herbage N concentration [Na in g kg−1 dry matter (DM)] and sward mass (DM Mg ha−1) was proposed previously for management of N fertilizer: Ni = 100 × Na/48DM−0.32. For the sake of simplification, we developed and evaluated a method based only on the N concentration of approximately the upper 7 cm of sward (Nus). Twenty‐one treatments of pure or dominant orchardgrass (Dactylis glomerata L.) swards, covering a wide range of N fertilizer rates, regrowth periods, sites, and years, were used to establish a relationship between conventional (Ni) and simplified (Nus) sward N status. Detailed studies were conducted on a subset of treatments to determine the N distribution along the length of the leaf and down the sward’s vertical profile. Analysis of N distribution among leaf segments for orchardgrass swards showed that Nus did not change over time with respect to Ni once there were about three leaves per tiller. Two close linear relationships between Nus and Ni were established, one for samplings made after three leaves had appeared on a tiller [about 500 degree‐days (DD) after defoliation of the sward] (r2 = 0.92; n = 62; SE = 2.8) and the other before this stage (r2 = 0.94; n = 12; SE = 3.3). We concluded that the Nus method is good enough to be used for assessing N sward status for a large range of defoliation regimes, without measurement of standing herbage mass: Ni = 2.94Nus − 20.59 and Ni = 2.28Nus − 12.07, respectively, after and before 500 DD.
Impact of Planter Type, Planting Speed, and Tillage on Stand Uniformity and Yield of Corn
Authors: Liu Weidong , Tollenaar Matthijs , Stewart Greg , Deen William
Published: July 2010

Planter type, maintenance, and operation play an important role in uniform stand establishment in corn (Zea mays L.). Research was conducted to determine if planter type affects corn yield by altering plant spacing and emergence variability and to determine if planting speed and tillage influence these effects. This experiment was performed at two locations in south‐central Ontario during a 2‐yr period. Treatments were established with conventional tillage (CT) and no‐tillage (NT) as main plots, three planter types (vacuum meter, finger‐pickup, and air seeder) with differing mechanisms including varied seed‐singulating mechanisms as subplots, and two planting speeds of 7.2 and 11.3 km per hour (kph) as sub‐subplots. Planter type affected stand uniformity with mean standard deviation (SD) of within‐row plant spacing of 7.9, 10.3, and 19.9 cm for vacuum meter, finger pickup, and air seeder, respectively. A higher SD was observed in NT for finger pickup and air seeder but remained the same for vacuum meter. For all planters, SD increased at faster planting speeds. The number of days required to achieve 50% emergence was similar between the vacuum meter and finger pickup but was greater for the air seeder, especially when planting speed was increased and NT was used. Final plant population was unaffected by planter and planting speed treatments. Overall, grain yields decreased 35.9 kg ha−1 for each centimeter increase in within‐row plant spacing SD and 292.8 kg ha−1 per day of delay in emergence. Results suggest that grower’s attention to corn planter mechanisms and maintenance is more critical under a NT system or when operating speeds are increased.
The Legume Content in Multispecies Mixtures as Estimated with Near Infrared Reflectance Spectroscopy Method Validation
Authors: Locher F. , Heuwinkel H. , Gutser R. , Schmidhalter U.
Published: July 2010

The legume content in multispecies mixtures can accurately be estimated by means of near infrared reflectance spectroscopy (NIRS) provided that there is a valid calibration. This study was conducted (i) to test the applicability of two narrow‐based calibrations, A and B (origin of the calibration sets: one farm, five harvests), for plant material not present in the calibration set and (ii) to compare the predictive ability of both models to a third, broad‐based calibration, C (different farms and harvests). The prediction accuracy of the NIRS models, A (end‐points calibration) and B (calibration with incremental standards), was tested with defined legume–grass mixtures of nine test sets, which differed in origin and harvesting dates. Most of the test‐set spectra were later used as additional calibration samples for Model C. Calibrations A and B, which differed in calibration design, showed varying root mean square errors of prediction for each of the nine test sets (A: 3.3–12.5%; B: 3.9–10.3%). The slope of the line from regression of NIRS predicted on true values ranged between 0.93 and 1.09 (r2 always > 0.92). All predictions were precise but biased. Prediction accuracy was worst for samples mixed of plant material that was grown in monoculture. After a bias correction and the exclusion of the mixtures of monocultural samples from the test sets, both models showed the same error (standard error of prediction after bias correction < 6%). Calibrations A, B, and C were compared by predicting two external test sets. The broad‐based Calibration C offered the same prediction accuracy as Calibrations A and B but did not reduce the bias. With Model C, there was no consistent reduction in the proportion of outliers in the test sets with a Mahalanobis distance > 3 compared with the Models A and B. It is concluded that predictions are biased even if more natural variability is included in the calibration set. Therefore, based on these data, a bias correction is always necessary. After a bias correction, all calibrations offered a highly accurate tool to estimate the legume content of mixtures independent of origin and harvesting dates. Contrary to our expectations, the most simple model, A, which was derived from the least number of calibration spectra and which represented the least natural variability, proved to be as accurate and robust in the prediction of independent test sets as the broader models, B and C.
Tillage and Nitrogen Application Impact on Cotton following Wheat
Authors: Wiatrak P. J. , Wright D. L. , Marois J. J. , Koziara W. , Pudelko J. A.
Published: July 2010

Tillage and N fertilization influence cotton (Gosspium hirsutum L.) growth and yield. The objective of the study was to evaluate the influence of two tillage systems (conventional tillage [CT] and strip‐till [ST]) and four N rates (0, 67, 134, and 202 kg N ha−1) on growth, development, and yield of ‘DP 5409’ cotton following wheat (Triticum aestivum L.). The experiment was conducted at the University of Florida's North Florida Research and Education Center in Quincy, FL, in 1995–1997. Lint yields, plant height, boll no. plant−1, and boll no. m−2 varied across years. With every 1 kg N ha−1 applied to cotton, lint yields increased by 1.74 and 1.53 kg ha−1 in 1996, and 2.76 and 1.76 kg ha−1 in 1997 for CT and ST, respectively. In 1995, maximum lint yields were estimated with 105 kg N ha−1 for CT. Averaged across years, cotton lint yield increase with N application greater than 67 kg ha−1 was not significant and tillage did not influence lint yields. Plant height, boll no. plant−1, and boll no. m−2 generally increased with increasing N rates, except for boll no. m−2 in the ST system in 1995. Greatest boll weight and lint weight boll−1 were obtained with the application of 134 kg N ha−1. Compared with CT, ST reduced boll no. plant−1 and increased boll no. m−2. Tillage did not influence plant height, boll weight, and lint weight boll−1. These results indicate that cotton can be grown successfully in ST and that yields may not increase significantly with rates >67 kg N ha−1
The Use of the Seventh Approximation in New Areas
Authors: Westin Fred C.
Published: July 2010

The Seventh Approximation was found to be very useful for classifying soils in Venezuela. The system was helpful in three ways: in classifying unfamiliar and little‐studied soils; in working with people generally unversed in soil classification; and in making agricultural predictions. In working with unfamiliar soils the Seventh Approximation provided quantitative definitions of most of the known soils of the world and also made provision for soils not included in the old system. The Seventh Approximation was understood by Spanish‐speaking botanists and geologists who were relatively untrained in soils, as well as by trained soil scientists. It was found that agricultural predictions were possible at all levels of abstraction used. Making predictions is important in new areas because the great need is to find the locations of the better soils for both dryland and irrigation development. The Seventh Approximation proved to be an effective framework around which to organize the soils information in new areas. Because it does this well it helps sell the soil surveyor and his science.