bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cover Crops Affect Sorghum Seedling Growth
Authors: Dabney Seth M. , Schreiber Jonathon D. , Rothrock Craig S. , Johnson Joseph R. 
Published: July 2010

AbstractRecently killed cover crops often interfere with crop seedling growth. Controlled‐environment and field studies were conducted to characterize the nature and persistence of cover crop interference with sorghum [Sorghum bicolor (L.) Moench] seedling growth and to test several seed‐zone management practices that might alleviate detrimental effects. Germination, root and shoot length, and disease incidence of sorghum germinated at 25°C for 5 d in soil collected 2, 4, 7, 14, 23, and 32 d after killing cover crops indicated legume cover crops were more detrimental to seedling growth than were nonlegumes. Surface residues, subsurface residues, and residue leachates contributed to the deleterious effects. Seedling shoot disease incidence of 50% persisted through 32 d when legume residues were mixed into soil or placed on top of soil at planting, but disappeared by 7 to 14 d if residues were removed. Pathogenic organisms isolated from lesions on seedlings indicated legume cover crops increased damage due to Rhizoctonia solani Kühn. In a no‐till field study, stand density was reduced 15% and aboveground seedling dry weight was reduced 45%, from 85 to 45 mg plant−1 28 d after planting, when sorghum was planted 1 d after killing crimson clover (Trifolium incarnatum L.) compared with planting 21 d or longer after killing. Insecticide, activated charcoal, or CaO2 seed coating improved sorghum stand density 15%, but did not affect seedling size. In‐furrow fungicide drench had no effect on stand density, but phytotoxic effects of the fungicide reduced shoot and root growth rates in both field and controlled‐environment studies. Residue removal combined with selected in‐furrow treatments may allow the interval between cover‐crop killing and successful no‐till planting to be reduced to less than 7 d.
Evaluation of a Field Test Kit for Measuring selected Soil Quality Indicators
Authors: Liebig Mark A. , Doran John W. , Gardner John C. 
Published: July 2010

AbstractA field soil quality test kit was developed to permit rapid assessment of numerous soil characteristics recognized as basic indicators of soil quality. This study was conducted to determine the accuracy and precision of indicator measurements with the field soil quality test kit. Data collected with the test kit were compared with that from standard laboratory analyses using soils from grassland and cropland on two farms in Stutsman County, North Dakota. Results obtained with the test kit for electrical conductivity, soil pH, soil nitrate, and gravimetric water content compared well with those found by standard laboratory analyses. Significant differences in soil respiration between the field and laboratory methods were attributed to the inclusion of root respiration in the test kit measurement and to differences in sampling time, disturbance, and soil depth. Repeated test kit measurements were, for the most part, no more variable than standard laboratory analyses except when the water status of soils neared saturation. This preliminary evaluation demonstrated the field test kit to be an effective screening tool for point‐scale assessment of soil quality by providing accurate and precise data over a range of soil conditions.
Yield Components and Forage Quality of Common Vetch during Pod Filling
Authors: Caballero Rafael , Barro C. , Rebolé A. , Arauzo M. , Hernaiz P. J. 
Published: July 2010

AbstractCommon vetch (Vicia sativa L.) is a high‐quality alternative forage legume in rainfed areas of the Mediterranean basin. Determining harvest strategies to maximize yield of available nutrients must include an assessment of morphological development, forage and grain yields, and changes in forage quality during seed filling. Field studies were conducted near Madrid, Spain, during the 1991–1992 and 1992–1993 growing seasons on a Typic Xerofluvent Entisol soil. Common vetch was sown in November and harvested in May and June of the following year. Maturity stages during pod filling were defined by progressively higher seed dry matter (DM) concentration (full bloom and 250–300, 450–550, and >800 g kg−1 seed DM). Total herbage, seed, and crude protein yields were compared. Measurements of plant partitioning, acid‐detergent fiber, and acid‐detergent lignin were carried out by harvesting individual plants at seven maturity stages, similarly defined, during pod filling (200‐250, 250‐300, 350‐450, 450‐550, 600‐700, 700–800, and >800 g kg−1 seed DM). Before 450–550 g kg−1 seed DM, forage, seed, and crude protein yields increased with advancing maturity. As maturity advanced beyond 450–550 g kg−1 seed DM, negative crop growth rates were found in the two growing seasons. Plant partitioning showed that the seed fraction in the harvested biomass varied from 74 g kg−1 DM at 200‐250 g kg−1 seed DM to 491 g kg−1 DM at 450–550 g kg−1 seed DM. Little change was observed in plant parts or seed weight beyond 450–550 g kg−1 seed DM. This last stage of maturity is recommended for maximizing nutrient yield for common vetch hay production.
Estimating Field Losses of Rice in Asia, Using Small Quadrat Samples
Authors: Bell Mark A. , McLaren Christopher G. , Patena George F. , Mendoza Dionisio C. 
Published: July 2010

AbstractField losses of rice (Oryza sativa L.) in small fields of Asia are rarely quantified. In developed countries, loss is often measured using devices attached to large combines. Such harvesting equipment is rarely used in Asia, so quadrat counts are more applicable. We estimated field losses of rice using a 10‐ by 10‐cm rigid quadrat in commercial fields on Luzon in the Philippines. Losses ranged from 66 to 503 kg ha−1. Due to the rapidity of the quadrat counts, sample variability throughout the field was easily assessed. By counting the number of seeds and multiplying by 22 to 25 (typical range for 1000‐kerneI weight), field loss (kg ha−1) was estimated directly. To estimate field losses within ±50 kg ha−1, a rule of thumb of three is suggested (i.e., the total number of samples required is approximately three tunes the average number of grains being counted in the sample). A sequential sampling procedure is presented for efficiently determining whether grain losses are below a specified tolerance. The quadrat method is an option for rapid assessment of losses, especially by farmers, where more sophisticated methods are not available.
Response of Spring Barley to Crop Rotation, Conservation Tillage, and Weed Management Intensity
Authors: Légère Anne , Samson Nathalie , Rioux Romain , Angers Denis A. , Simard Régis R. 
Published: July 2010

AbstractConstraints to the adoption of conservation tillage in central and eastern Quebec potentially include cool wet springs, short growing seasons, and variable precipitation patterns. This study was conducted to determine the suitability of conservation tillage practices to cereal cropping systems in this area of Quebec. The effects of crop rotation [spring barley (Hordeum vulgare L.) monoculture; spring barley‐red clover (Trifolium pratense L.) rotation], tillage [fall moldboard plow (MP); fall chisel plow (CP), and direct‐seeded no‐till (NT)], and weed management intensity (intensive, moderate, minimum) on populations and dry weights of crop and weeds at midseason, and on grain yields and yield components were examined on a Kamouraska clay and a Saint‐André gravelly‐sandy loam. On the clay site, moderate weed management in NT treatments resulted in crop establishment, growth, and yields comparable to those in MP treatments. Over five years, grain yields in NT treatments averaged 2877 kg ha−1, compared with 2870 and 2260 kg ha−1 in MP and CP, respectively. Grain yields were also consistently but not statistically higher in the rotation (3014 kg ha−1) than in the monoculture (2322 kg ha−1). On the loam site, crop establishment, growth, and yields responded negatively to reductions in tillage and weed management intensity. Barley stand establishment and weed control in CP and NT treatments on the loam site were less successful in the monoculture than in the rotation. No‐till grain yields (1494 kg ha−1) were on average 7% lower than CP yields (1608 kg ha−1), and 29% lower than MP yields (2076 kg ha−1). Rotation had no effect on grain yields on the loam site. Findings confirm the potential of conservation tillage to generate sustained yield returns in spring barley cropping systems, provided that proper attention is given to critical aspects of the cropping system, including crop establishment and weed management.
SAS‐STABLE: Stability Analyses of Balanced and Unbalanced Data
Authors: Magari Robert , Kang Manjit S. 
Published: July 2010

AbstractStability concept is often used to analyze genotype × environment interaction (G × E), by partitioning G × E variance into stability variance components for each genotype. A significant stability variance for a particular genotype indicates lack of stability. An existing computer program (STABLE) calculates the yield‐stability (YSi) statistic for balanced data sets only. Therefore, we developed a program (SAS‐STABLE) that calculates stability variances for balanced as well as unbalanced data sets and is based on the restricted maximum likelihood method. Data may be stored in SAS files or other files that can be retrieved by SAS commands and statements used for data management. This program is for the Windows version of SAS for IBM‐PC compatible computers; a mainframe version is also available. Variance components are solved by iterating on some starting values. Prior knowledge of the values of variances would reduce number of iterations to reach convergence and save execution time. SAS‐STABLE can easily incorporate one or more covariates into the model and remove their effects from G × E variances for each genotype. Variances are tested based on the hypothesis H0: σ2 = 0, assuming normal distribution.
A High Oil Pollinator Enhancement of Kernel Oil and Effects on Grain Yields of Maize Hybrids
Authors: Lambert Robert J. , Alexander D. Eugene , Han Z. J. 
Published: July 2010

AbstractSeveral attempts to develop high oil (HO) maize (Zea mays L.) hybrids that are competitive in yield have met with limited success, because of the negative association between oil levels and grain yields. Generally, HO hybrids have high oil kernels but with reduced starch levels, smaller endosperm, and reduced kernel size. The objective of the study was to determine if the use of a high oil maize pollinator could reduce the potential grain yield losses associated with high oil maize production. Nine different single‐cross hybrids were grown for 3 yr and pollinated by two different pollinators. To produce maize hybrids with different kernel oil concentrations under open‐pollinated conditions, the nine hybrids were pollinated by a high oil pollinator (HOP) and by a normal oil pollinator (NOP). To control pollinations, all nine hybrids were detasseled. A split‐plot design allowed for a comparison of the effects of the two pollinators. The four normal oil (NO) hybrids produced oil concentrations in the 60 to 70 g kg−1 range on a dry weight basis when pollinated by a HOP, with no reduction in grain yields. These same hybrids produced oil concentrations in the 47 to 55 g kg−1 range and similar yields when pollinated by a NOP. The four HO hybrids produced yields about 15% lower than the NO hybrids when pollinated by a HOP and about 12% lower yields when pollinated by a NOP. The normal fertile check hybrid produced yields differing by only 1% with the two pollinators, but the oil levels showed an increase of 17 g kg−1 for a HOP relative to a NOP. This increase in oil levels of the NO hybrids pollinated by a HOP is the result of a small increase in germ weight, an increase concentration of oil in the germ, and a reduction in the percentage of endosperm. The changes in kernel traits do not appear to reduce grain yields of the NO hybrids, but do increase oil levels. The consequence of this procedure is to trick the sporophyte into producing greater amounts of oil in the germ.
Weed Seedbanks and Corn Growth following Continuous Corn or Alfalfa
Authors: Clay Sharon A. , Aguilar Immer 
Published: July 2010

AbstractSpecific crop rotations may reduce weed problems and supplement agrichemical inputs. This study, conducted from 1991 through 1994, compared weed densities and corn (Zea mays L.) growth in continuous corn rotation (C/C) and in an alfalfa (Medicago sativa L.)/alfalfa/corn rotation (A/C) among different input levels (tillage, herbicide, and fertilizer rates varied to achieve high, intermediate, and low treatments). Alfalfa suppressed weeds. During establishment, grass and broadleaf weeds made up about 36 and 10% of the forage biomass, respectively. During the second year, grass and broadleaf weeds made up no more than 17 and 4% of the forage biomass, respectively. Weed seed density in both A/C and C/C corn low‐input plots averaged about 15 000 seeds m−2 in 1993; however, grass seed comprised 73% of the C/C seedbank, but only 26% of the A/C seedbank. In 1994, weed seed density increased to 38 000 seeds m−2 in the low‐input A/C corn, and grass species made up 55% of the seedbank. However, grass densities in A/C and C/C low‐input corn averaged about 300 and 4000 shoots m−2, respectively, each year. No grain was harvested in C/C low‐input corn, due to intense weed competition. Grain yield in A/C low‐input corn was 37% of the A/C high‐input treatment in 1993, 66% of the yield in A/C high‐input treatment in 1994, and similar to yield in the C/C medium‐input treatment both years. Alfalfa in rotation with corn may be used to reduce weed competition while sustaining yield.
Noncontiguous Replications in Soybean Performance Tests
Authors: Wilcox James R. , Zhang Guodong 
Published: July 2010

AbstractSoybean [Glycine max (L.) Merr.] performance trials are commonly conducted in randomized complete block designs with contiguous replications. Local environmental hazards such as hail, flooding, or herbicide drift can result in the loss of entire experiments and the included germplasm with contiguous replications. Noncontiguous replications, spatially separated at a location, minimize chances of local hazards affecting all replications. Our objective was to compare the validity of data from noncontiguous vs. contiguous replications of soybean performance trials. Eleven performance tests were conducted over a 3‐yr period in three‐replicate randomized complete block designs using both contiguous and noncontiguous replications. Distance between noncontiguous replications varied from 200 to 800 m. Twenty‐five to 40 lines in either Maturity Group II or III were evaluated in each test. Traits measured were plant maturity, mature plant height, and seed yield. Variability among lines was significant (P = 0.01) using both contiguous and noncontiguous replications in all 11 tests for plant maturity and plant height. Variability among lines was significant (P = 0.05) for seed yield in 7 of 11 tests of contiguous replications and in 9 of 11 tests of noncontiguous replications. Correlation coefficients among line means between the two types of replication varied from 0.83 to 0.98 for maturity, from 0.51 to 0.94 for plant height, and from 0.51 to 0.89 for seed yield in those tests where significant variation was observed among lines. Evaluating soybean lines in tests using noncontiguous replications requires no more effort or space than using contiguous replications. The results demonstrate that noncontiguous replications are an effective and useful alternative to contiguous replications for soybean performance tests.
Plant Determinants of Mycorrhizal Dependency in Soybean
Authors: Khalil Samina , Loynachan Thomas E. , Tabatabai M. Ali 
Published: July 2010

AbstractEven though the mycorrhizal relationship is thought to be important in nutrient and water uptake by plants, earlier work showed that soybean cultivars differ in responsiveness. The reasons for cultivar differences are unclear. The objective of this growth‐chamber study was to relate plant‐growth parameters and rooting characteristics of three soybean cultivars to mycorrhizal dependency (MD). The soybean cultivars were chosen from a preliminary study to represent a range in MD values from high (Glycine soja Sieb. & Zucc. PI 468916; referred to hereafter as Soja), to intermediate [G. max (L.) Merr. cv. Mandarin] and low (G. max cv. Swift). Shoot weight, P percentage in shoot tissue, total shoot P uptake, P use efficiency, rate of growth, and root acid phosphatase activity were measured at three harvests when plants were grown at three relative P levels, each with and without mycorrhizal fungal (Gigaspora margarita Becker & Hall) colonization. Soja developed an active symbiosis more quickly than Swift or Mandarin, and mycorrhizae clearly aided in P uptake. When averaged across harvests at low P, mycorrhizal Soja had 7.8 times greater total shoot P than nonmycorrhizal Soja. Comparable values were 2.4 for Mandarin and 1.5 for Swift. Soja roots showed higher phosphatase activity and a higher percentage increase in phosphatase activity with mycorrhizal colonization than did the other two cultivars. Nonmycorrhizal Soja root lengths (avg. 1401 cm) at 5‐wk growth were significantly shorter than Mandarin (2303 cm) and Swift (2236 cm) root lengths. The mean diameter of lateral roots of Soja (0.38 mm) was greater than that of Mandarin or Swift (≈0.26 mm). Root lengths and root surface areas were negatively correlated (P < 0.01) with MD.
Microscopic Changes in Soil Structure During Compression
Authors: Day Paul R. , Holmgren George G. 
Published: July 2010

AbstractCompressed specimens of soil were examined microscopically to determine the nature of the changes occurring in moist soil during the application of pressure. A small compression chamber was filled loosely with moist soil aggregates, and the pressure was applied gradually in a controlled manner. The compressed material was removed at various stages and dried. Polished sections were then prepared. The results have been preserved in a series of photomicrographs and show that the volume changes are attributable in large part to plastic deformation of the aggregates. Deformation occurred readily at the lower plastic limit, causing a progressive closing of the interaggregate spaces as the pressure was increased. At water contents below this limit deformation appeared to be localized in the areas of contact between aggregates and consisted mainly of flattening of the aggregates against one another. The incomplete closing of the interaggregate spaces at low water contents was attributed to the increased shearing strength of the material. The theory has been advanced that during compression localized stresses in excess of the shearing strength occur in the contact areas between aggregates and that the resulting flattening causes a dimunition of stress on account of the distribution of the load over a greater area; deformation ceases when the shearing stress falls below the shearing strength. According to this theory, the flattening phenomen acts as a check against unlimited deformation at any given pressure.
Single Strains and a Mixture of Rhizobium trifolii for Inoculating True Clovers
Authors: Erdman Lewis W. , Means Ura Mae 
Published: July 2010

AbstractTwenty strains of Rhizobium trifolii were grown separately and equal portions were compounded into a single mixed humus culture. Twelve species of Trifolium were inoculated with this mixed culture, with a single good strain, and with a poor strain. On Trifolium incarnatum and T. fragiferum, the mixed culture was significantly better than the single good strain culture. On T. subterraneum, T. hirtum, and T. lappaceum, the single good strain was significantly better than the mixed culture. On the seven other species, T. repens, T. repens var. ladino, T. pratense, T. hybridum, T. nigrescens, T. glomeratum, and T. resupinatum, no significant differences were found between the single good strain and the mixed culture. The presence of poor strains in the mixed culture apparently had no harmful effect on its efficiency to inoculate the 12 different species of true clovers.
Potassium Ion Fixation, Equilibria, and Lattice Changes in Vermiculite
Authors: Dennis Everett J. , Ellis Roscoe 
Published: July 2010

AbstractThe influence of different levels of added potassium on the equilibrium values of water‐soluble, exchangeable, and “fixed” potassium in a vermiculite system was investigated by chemical methods. X‐ray diffraction techniques were used to establish the levels of added potassium necessary to result in changes in the basal “d” spacing of the vermiculite lattice. The effects of dehydration and complementary ion were studied.In general, fixation of potassium by vermiculite against chemical extraction was associated with a change in the basal “d” spacing of the vermiculite lattice as shown by X‐ray diffraction. However, some potassium was fixed against chemical extraction which was not detected by the X‐ray diffraction method employed. Dehydration increased potassium fixation. Calcium and sodium systems were compared to determine the influence of the complementary ion on the fixation process. For a given level of exchangeable potassium, more fixation of potassium occurred when calcium was the complementary ion.
Soil Chemical Characteristics of Recent Volcanic Ash
Authors: Bornemisza Elemer , Morales José C. 
Published: July 2010

AbstractVolcanic ash, emitted by Irazú volcano in Costa Rica during 1963 and 1964, was evaluated for its agricultural value. The evaluation included leaching loss studies in lysimeters and measurements of nutrients extracted with various solutions. The CEC of the ash is about 1.85 meq/100 g, and its pH in water is 5.1; it contains little soluble or exchangeable Mn. Lysimeter experiments showed that Irazú ash does not fix phosphorus or retain cations added as fertilizers. The ash is wettable and forms, when wetted, a thin, hard, cemented surface crust.
Effect of Phosphate and Chloride Salts on Ammonification in Waterlogged Soils
Authors: Ryan J. A. , Sims J. L. , Peaslee D. E. 
Published: July 2010

AbstractA survey of 15 different soil types indicated ammonification under waterlogged conditions was usually decreased by addition of KH2PO4, although occasional increases were observed. Ammonification in the Pembroke soil was studied in more detail with varying concentrations (0, 1 × 10‐3, 1 × 10‐2, 2.5 × 10‐2, and 1 × 10‐1M) of KH2PO4, NaH2PO4, KCl and NaCl and between 7 and 35 days of incubation. In general, ammonification increased as the incubation period increased and decreased as the salt concentration increased. There was a significant interaction between salt treatments and incubation periods, reflecting the tendency of ammonification to be decreased more at intermediate incubations than at longer incubations. Potassium salts generally depressed ammonification more than did Na salts, especially in the phosphate series. Of the anions, the depression was greater with Cl salts than with P salts for most short term incubations, but the reverse was true for the 35‐day incubation. The critical concentration for the salts in this study was about 2.5 × 10‐2M.