bluuebunny/crossref_metadata_2025 huggingface dataset:
Residue Removal and Nitrogen Fertilization Affects Tiller Development and Flowering in Meadow Bromegrass
Authors: Loeppky Heather A. , Coulman Bruce E.
Published: July 2010

Flowering and seed yield in many temperate grasses are dependent on floral induction in the previous fall. Field experiments were conducted in Saskatchewan to determine the effect of crop residue removal and N fertilization on tiller and panicle development in meadow bromegrass (Bromus riparius Rehm.). Four residue removal treatments (none, after harvest, October, and after harvest + October) and three N treatments (0, 50, and 100 kg N ha−1) were applied in each of 2 yr. Tiller density and leaf stage were determined in fall and spring; panicle density was determined just before seed harvest each year. Removing crop residue generally increased tiller and panicle density. However, fall tiller density decreased at Saskatoon in 1996 due to dry conditions, regardless of residue removal. Because fewer tillers were present in the fall when conditions that promote flowering prevailed, panicle density was reduced by 62% compared with the previous year. Nitrogen generally did not affect tiller density or development. However, in the spring of 1996, 100 kg N ha−1 with a single residue removal increased leaf stage from 2.4 to 2.6 leaves tiller−1. This rate of N with double residue removal reduced leaf stage to 2.2 leaves tiller−1 due to winter injury. Fall tiller density and panicle production were similarly affected. As a result of winter injury and drought, fall tiller density and development were not highly or frequently correlated with panicle or seed production. Hence, fall tiller density and development in the prior year cannot be used as a tool to predict seed yield.
Planting Date, Hybrid Maturity, and Plant Population Effects on Soil Water Depletion, Water Use, and Yield of Dryland Corn
Authors: Norwood Charles A.
Published: July 2010

Dryland corn (Zea mays L.) yield in western Kansas is limited by high temperatures and low rainfall. The number of corn hectares has increased in recent years due to improved hybrids, acceptance of reduced‐ and no‐till practices, and favorable weather conditions. Research was conducted near Garden City, KS, from 1996 through 1999 to determine the effects of hybrid maturity, planting date, and plant population on soil water depletion, water use efficiency (WUE), and yield of dryland corn. Five hybrids with relative maturities of 75 (H1), 92 (H2), 98 (H3), 106 (H4), and 110 d (H5) were planted in mid‐April (D1) and early May (D2) of each year (the 75‐ and 92‐d hybrids were not planted in 1996) and thinned to populations of 30000 (P1), 45000 (P2), and 60000 (P3) plants ha−1 in a wheat (Triticum aestivum L.)–corn–fallow rotation. Depletion of soil water increased with hybrid maturity. In addition, higher populations tended to remove more water from the lower portion of the profile. Hybrids usually yielded more at the D2 planting date. In the most stressful year, grain yield averaged 97% more for D2 and water use efficiency averaged 85% more. For the 1997 through 1999 period, WUEs for D2 were 43, 45, 29, 30, and 37% higher vs. D1 for H1 through H5, respectively. In summary, earlier planting decreased yield and WUE. The highest yields and WUEs were achieved with the later planting date, combined with later‐maturing hybrids and higher plant populations.
Weather Impacts on Maize, Soybean, and Alfalfa Production in the Great Lakes Region, 1895–1996
Authors: Andresen Jeffrey A. , Alagarswamy Gopal , Rotz C. Alan , Ritchie Joe T. , LeBaron Andrew W.
Published: July 2010

Weather and climate have had major influences on crop production in the Upper Great Lakes states of Michigan, Minnesota, and Wisconsin during the past century. However, isolation of the impact of weather is made difficult by the confounding effects of technological improvements in agriculture, which have resulted in significant grain yield increases. The objective of this study was to identify climatological impacts involved with the production of three crops commonly grown in the region—alfalfa (Medicago sativa L.), maize (Zea mays L.), and soybean [Glycine max (L.) Merr.]—without the influence of technology, and trends of relevant agroclimatological variables during the period 1895–1996. The models DAFOSYM, CERES‐Maize, and SOYGRO models were used to simulate crop growth, development, and yield of the three crops, respectively. Regionally, low precipitation and moisture stress were chief limitations to simulated crop yields. Simulated maize and soybean yield series were found to increase with time an average of 11.4 kg ha−1 yr−1 and 4.9 kg ha−1 yr−1, respectively, across the study sites during the study period. These increases were associated with average study period increases in total seasonal precipitation of 0.4 mm yr−1 and decreased total seasonal potential evapotranspiration of 0.2 mm yr−1. No consistent trends were found for alfalfa. The simulated yield results support previous research identifying a period of benign climate, which favored crop production in the region from 1954 to 1973, and was preceded and followed by periods of relatively greater yield variability.
Tillage System, Fertilizer Nitrogen Rate, and Timing Effect on Corn Yields in the Texas Blackland Prairie
Authors: Torbert H. Allen , Potter Kenneth N. , Morrison John E.
Published: July 2010

New N management and conservation tillage systems are needed to improve agricultural sustainability on the Blackland Prairie of Texas. In 1994, an experiment was established to determine plant response to N fertilizer rate and timing within three different tillage systems. A split plot experiment with four replications was established on a Houston Black clay (fine, smectitic, thermic Udic Haplusterts) soil. The main plots were chisel tillage system without beds (conventional for the area), chisel tillage system with raised wide beds, and no‐tillage system with raised wide beds. The subplots were seven fertility treatments: four fertility rates (0, 56, 112, and 168 kg N ha−1applied at planting) and three timing treatments (N applied in the fall, at planting, and split between at planting and 30 d later). The crop rotation was wheat (Triticum aestivumL.), corn (Zea maysL.), and sorghum [Sorghum bicolor(L.) Moench]. The experimental treatments were imposed on corn each year for 4 yr. Plant samples were collected for grain yield, biomass production, and N uptake. Grain yield ranged from 150 to 8435 kg ha−1. In wet years, grain yields and N uptake increased with N fertilizer up to 168 kg N ha−1, and fall application reduced yields 30% when compared with fertilizer application at planting. The highest yields were observed with the no‐tillage. Results from this study indicate that application of fertilizer in the fall may result in lost yield potential and that conservation tillage systems may be the most reliable in the Texas Blackland Prairie.
Losses in Yield, Quality, and Profitability of Cotton from Improper Harvest Timing
Authors: Bednarz Craig W. , Shurley W. Don , Anthony W. Stanley
Published: July 2010

Excessive weathering may diminish cotton (Gossypium hirsutum L.) lint yield and fiber quality to the extent that economic losses occur for the producer. Our objective was to determine the effects of systematic delayed harvest on cotton lint yield, fiber quality, and profitability. Experiments were conducted from 1998 to 2000 at the Coastal Plain Experiment Station, Tifton, GA, on a Tifton loamy sand (fine‐loamy, kaolinitic, thermic Plinthic Kandiudults). The treatments consisted of a standard harvest‐aid combination applied at weekly intervals over a 13‐wk period beginning at first open boll. Harvest aids were applied to each plot according to its week after first open boll designation and machine harvested 2 wk thereafter. After ginning, fiber quality was determined on lint samples from each plot. High volume instrument (HVI) fiber length uniformity was greatest in 1999 and 2000 when harvest aids were applied between 58 and 88% open boll, while the advanced fiber information system (AFIS) fiber length by number coefficient of variation and short fiber content by number were lowest when harvest aids were applied from 40.1 to 46.8% open boll. The HVI upper half mean fiber length and the AFIS mean fiber length by number were greatest when harvest aids were applied between 39.1 and 56.7% open boll. In 1999 and 2000 lint yield and adjusted gross income were greatest when harvest aids were applied from 76.5 to 89.0% open boll. Results from this study indicate optimum fiber quality is established earlier during boll opening than lint yield and profitability.
Seasonal Variations in Condensed Tannin Concentration of Three Lotus Species
Authors: Gebrehiwot Lulseged , Beuselinck Paul R. , Roberts Craig A.
Published: July 2010

Condensed tannins (CTs) are commonly found in herbage of Lotus spp. and can have beneficial or detrimental effects on feed value and animal performance. Our objectives were to (i) determine the level of CT concentration and its seasonal variations in three widely grown Lotus spp.; (ii) assess the distribution of CTs in leaves, stems, and flowers; and (iii) determine if herbage of greenhouse‐grown Lotus spp. contains CT concentrations with equivalent rank to field‐grown plants. Field herbage samples were taken in spring, summer, and fall and analyzed for CTs by near infrared reflectance spectroscopy (NIRS). Herbage of big trefoil (L. uliginosus Schkur.) germplasm ARS‐1221 and narrowleaf trefoil (L. glaber Mill.) germplasm ARS‐1207 had the greatest and lowest CT concentrations averaging 154 and 8 g catechin equivalent (CE) kg−1 dry matter (DM), respectively. The birdsfoot trefoil (L. corniculatus L.) cultivar ARS‐2620 had a greater CT concentration than ‘Norcen’, but both had moderate CT levels averaging 39 and 23 g CE kg−1 DM, respectively. Herbage CT concentration of Norcen, ARS‐2620, and ARS‐1221 was higher in spring and summer compared with fall while that of ARS‐1207 was low in spring, summer, and fall. Generally, stems had less CT than leaves and flowers, but there was no detectable CTs in stems of ARS‐1207. The rankings of the four entries for herbage CT concentration in the greenhouse and field were the same. This is the first report of CT concentrations for the germplasms ARS‐1221 and ARS‐1207, which are suitable candidates for genetic improvement to develop cultivars with desirable CT levels.
Nutritive Value of Rhizoma Peanut Growing under Varying Levels of Artificial Shade
Authors: Johnson Sue Ellen , Sollenberger Lynn E. , Andrade Ivo F. , Bennett Jerry M.
Published: July 2010

‘Florigraze’ rhizoma peanut (Arachis glabrata Benth.) is productive and persistent under moderate shade and has potential as an understory forage for grazing in southeastern U.S. pine (Pinus spp.) plantations. When grown in full sun, Florigraze has high forage quality, but the effect of shade on its nutritive value is not known. A 2‐yr field study was conducted on a siliceous, hyperthermic Arenic Paleudult soil to determine nutritive value of Florigraze herbage when grown under 34, 54, 78, and 100% of incident photosynthetic photon flux density (PPFD). Treatments were arranged in three replicates of a randomized complete block design, and there were three harvests in both 1989 and 1990. Leaf crude protein (CP) increased 20 to 40 g kg−1 as PPFD increased from 34 to 100% in both years while leaf in vitro organic matter digestibility (IVOMD) increased 20 to 30 g kg−1 and neutral detergent fiber (NDF) decreased 20 to 50 g kg−1 with increasing PPFD only in the second year. Stem CP increased 10 to 20 g kg−1 and IVOMD 50 to 100 g kg−1 with increasing PPFD in at least two harvests each year while NDF and lignin concentrations decreased with increasing PPFD (50–80 and 15–25 g kg−1, respectively). In conclusion, leaf and stem nutritive value of shaded rhizoma peanut are lower than when grown in full sun, but they are not so low as to limit use of rhizoma peanut as an understory forage crop.
Climate Change and Winter Survival of Perennial Forage Crops in Eastern Canada
Authors: Bélanger Gilles , Rochette Philippe , Castonguay Yves , Bootsma Andrew , Mongrain Danielle , Ryan Daniel A. J.
Published: July 2010

Severe winter climatic conditions cause recurrent damage to perennial forage crops in eastern Canada. Predicted increases of 2 to 6°C in minimum temperature during winter months due to global warming will likely affect survival of forage crops. Potential impacts of climate change on overwintering of perennial forage crops in eastern Canada were assessed using climatic indices reflecting risks of winter injuries related to cold intensity and duration, lack of snow cover, inadequate cold hardiness, soil heaving, and ice encasement. Climatic indices were calculated for 22 agricultural regions in eastern Canada for the current climate (1961–1990) and future climate scenarios (2010–2039 and 2040–2069). Climate scenario data were extracted from the first‐generation Canadian Global Coupled General Circulation Model. Compared with current conditions, the hardening period in 2040 to 2069 would be shorter by 4.0 d, with a lower accumulation of hardiness‐inducing cool temperatures. The period during which a temperature ≤−15°C can occur (cold period) would be reduced by 23.8 d, and the number of days with snow cover of at least 0.1 m would be reduced by 39.4 d. Consequently, the number of days with a protective snow cover during the cold period would be reduced by 15.6 d. Under predicted future climate, risks of winter injury to perennial forage crops in eastern Canada will likely increase because of less cold hardening during fall and reduced protective snow cover during the cold period, which will increase exposure of plants to killing frosts, soil heaving, and ice encasement.
Weed Control for Stand Duration Perennial Ryegrass Seed Production
Authors: Mueller‐Warrant George W. , Rosato S. Caprice
Published: July 2010

Weed control was a major concern of Oregon grass seed growers during their transition from open‐field burning to mechanical methods of managing postharvest residues. This study aimed to determine (i) efficacy of herbicides on volunteer perennial ryegrass (Lolium perenne L.) seedlings, (ii) whether treatments required for weed‐free seed production could be reapplied annually without damaging stands, (iii) whether interactions between residue management and herbicides occurred, and (iv) whether weeds would increase over time. Twelve herbicide treatments and two residue management systems were compared for 3 yr in three commercial perennial ryegrass fields sown in 1991. Eight preemergence followed by postemergence herbicide treatment sequences provided good control (avg. 4% ground cover) of volunteer perennial ryegrass seedlings in the 1992–1993 growing season at all three sites, and in 1994–1995 at one of two sites. For the other sites and years, control ranged from good (avg. 7% ground cover) for 2.2 kg a.i. ha−1 rake‐incorporated preemergence pendimethalin [N‐(1‐ethylpropyl)‐3,4‐dimethyl‐2,6‐dinitrobenzenamine] followed by postemergence 0.14 kg a.i. ha−1 oxyfluorfen [2‐chloro‐1‐(3‐ethoxy‐4‐nitrophenoxy)‐4‐(trifluoromethyl)benzene] plus 1.3 kg a.i. ha−1 diuron [N′‐(3,4‐dichlorophenyl)‐N, N‐dimethylurea] to poor (avg. 55% ground cover) for postemergence‐only 0.28 kg a.i. ha−1 oxyfluorfen plus 1.8 kg a.i. ha−1 diuron. Herbicide treatments affected perennial ryegrass seed yield, with an average yield loss of 3.2 kg ha−1 for each 1% increase in seedling ground cover. Vacuum sweep residue removal improved weed control over bale–flail chop–rake treatment in all tests, but increased yield only once. Annual bluegrass (Poa annua L.) occurred only in plots that had not received pendimethalin.
Profile Water Balance Model under Irrigated and Rainfed Systems
Authors: Mandal Uttam Kumar , Sarma K. S. Sundara , Victor U. S. , Rao N. H.
Published: July 2010

A profile moisture model has been developed to evaluate the seasonal soil moisture fluctuation with respect to soil characteristics and land use pattern under irrigated and rainfed conditions in an area of agricultural fields. Daily rainfall and irrigation were used as model inputs. Instantaneous uniform redistribution of soil moisture in the effective root zone and negligible contribution of soil water through upward flux were assumed. An empirical model was used to determine the root depth. Runoff was estimated from rainfall data using the curve number technique of the Soil Conservation Service adapted for conditions in India and combined with a soil moisture–accounting procedure. The modified Penman method was used to calculate the reference evapotranspiration. To calculate the crop coefficient (Kc), regression equations were developed taking Kc as the dependent variable on normalized difference vegetation index. This model was very easy to parameterize and required a minimum soil data set of field capacity and permanent wilting point. To evaluate model performance, observed values of soil water were taken for wheat (Triticum aestivum L.) in the Mehrauli (sandy loam to loam texture) and Daryapur (loamy texture) soil series under irrigated conditions and for gram (Cicer arietinum L.) in the Jagat (clay loam texture) and Holambi (loam texture) soil series under rainfed conditions in Delhi. The r2 and D index between observed and predicted soil water values varied between 0.67 and 0.77 and 0.83 and 0.93, respectively.
Cultivar and Herbicide Selection Affects Soybean Development and the Incidence of Sclerotinia Stem Rot
Authors: Nelson Kelly A. , Renner Karen A. , Hammerschmidt Ray
Published: July 2010

Glyphosate‐resistant (GR) soybean [Glycine max (L.) Merr.] is produced on a majority of U.S. soybean hectares. Concerns have been expressed regarding interactions of herbicides such as glyphosate and Sclerotinia stem rot [Sclerotinia sclerotiorum (Lib.) de Bary]. Research evaluated the effect of herbicides on growth, phytoalexin production, incidence of Sclerotinia stem rot, and grain yield of GR and isogenic nonresistant cultivars in 1998 and 1999. Lactofen at 70 g a.i. ha−1 delayed reproductive development, reduced leaf area index (LAI), reduced Sclerotinia stem rot lesion diameter 2 to 26 d after treatment (DAT), increased phytoalexin production 2 to 26 DAT, reduced disease severity index (DSI), and increased yield of ‘Great Lakes 2415’ (GL2415) by 510 kg ha−1 compared with untreated soybean. Glyphosate at 840 g a.e. ha−1 increased disease severity index in ‘Great Lakes 2600’ (GL2600) and ‘Pioneer 93B01’ (P93B01) GR compared with untreated soybean while yield of ‘Novartis S20‐B9’ (S20‐B9) GR treated with glyphosate was 650 kg ha−1 greater than untreated soybean. Thifensulfuron at 4.5 g a.i. ha−1 delayed reproductive development, reduced LAI, and did not affect phytoalexin production of ‘Novartis S 19–90’ (S 19–90) or S20‐B9 GR but increased grain yield of ‘Novartis S 12–49’ (S 12–49) by 450 kg ha−1 compared with untreated soybean. S 12–49 and GL2415 treated with thifensulfuron had lower disease severity index and increased yield compared with GR isolines. Reduction of disease severity index following lactofen may be attributed to increased phytoalexin production, reduced LAI, and delayed reproductive development; however, increased yield was observed for only one of eight cultivars. Producers can reduce Sclerotinia stem rot with postemergence herbicides, but soybean yield did not necessarily increase.
Roundup Ready Soybean: Glyphosate Effects on Fusarium solani Root Colonization and Sudden Death Syndrome
Authors: Njiti Victor N. , Myers Oval , Schroeder Daniel , Lightfoot David A.
Published: July 2010

During 1997, the first year of widespread use of glyphosate (N‐[phosphonomethyl]glycine) on Roundup Ready (RR) soybean [Glycine max (L.) Merr.] a severe sudden death syndrome (SDS) epidemic occurred and several RR cultivars were affected. Effects of glyphosate on colonization of soybean root by Fusarium solani (Mart.) Sacc f. sp. glycines (Fsg) and SDS were evaluated. Five RR cultivar pairs that contrasted for SDS resistance from maturity groups (MG) II to VI were evaluated with and without glyphosate application. The MG II and III cultivars were evaluated near Bloomington, Pontiac, and Mahomet in central Illinois and the MG IV, V, and VI cultivars were evaluated near Harrisburg, Ullin, and Valmeyer in southern Illinois. The Fsg root infection severity (IS), colony forming units per gram of root (CFU), SDS leaf scorch disease index (DX), and grain yield were determined. Across environments within each MG, there were no significant effects of glyphosate on IS, CFU, and DX. Significant differences were expected between cultivars but only observed in some MG. There was no significant effect of glyphosate on yield. Significant Glyphosate × Cultivar interactions occurred for yield in MG VI, in favor of the glyphosate sprayed subplots. In this study root colonization by Fsg and SDS leaf symptoms did not significantly increase following the application of glyphosate. Data from this study indicate that the development of SDS on RR soybean is influenced by genotype. Farmers planting RR soybean in Fsg infested fields are encouraged to select cultivars with resistance to SDS.
Summer Grazing Strategies following Early‐Season Grazing of Big Bluestem
Authors: Mousel Eric M. , Schacht Walter H. , Moser Lowell E.
Published: July 2010

Big bluestem (Andropogon gerardii Vitman) has a rapid growth phase that begins in early to mid‐June in eastern Nebraska. During this rapid growth phase, rate of biomass accumulation exceeds intake rate of grazing livestock, resulting in low levels of harvest efficiency. To delay the rapid growth phase, big bluestem pasture can be grazed in mid‐ to late May without affecting herbage yields for the remainder of the growing season. A pasture experiment was conducted in 1999, 2000, and 2001 near Mead, NE. The objective was to determine the effect of timing and frequency of grazing big bluestem pasture, following a May grazing period, on cumulative pregrazing yields, cumulative herbage disappearance, resulting harvest efficiency, leaf/stem ratio, and stand persistence. Yield and morphological characteristics were obtained immediately before and after each grazing period, and basal cover of big bluestem was estimated annually. May grazing had no effect (P < 0.1) on cumulative pregrazing yields and resulted in an increase of cumulative herbage disappearance (3638 vs. 2673 kg ha−1) and leaf/stem ratio (2.02 vs. 2.83) compared with paddocks with no May grazing. Grazing at the vegetative stage in June compared with the elongation stage resulted in an increase in cumulative pregrazing yields (10774 vs. 9510 kg ha−1), cumulative herbage disappearance (4116 vs. 3194 kg ha−1), and leaf/stem ratios (2.57 vs. 1.98). Grazing at the elongation stage in June followed by a grazing period in early August is not an advisable management strategy.
Rice Yield and Soil Chemical Properties as Affected by Precision Land Leveling in Alluvial Soils
Authors: Walker Timothy W. , Kingery William L. , Street Joe E. , Cox Michael S. , Oldham J. Larry , Gerard Patrick D. , Han F. Xiang
Published: July 2010

In 1998 and 1999, two soil series representative of a large percentage of rice (Oryza sativa L.) growing hectarage in the Mississippi Delta were sampled in increments to a depth of 120 cm. Measurements were made to determine how extractable levels of Ca, K, Mg, Na, P, and Zn as well as the total N content and soil pH varied with respect to soil profile depth. Total N, extractable P, Zn, Ca, and pH all tended to decrease with depth while Na tended to increase. Only small differences were seen in Mg and K concentrations. An on‐farm study was conducted in 2000 and 2001 to further investigate the effects of precision land leveling on pH and concentrations of organic matter and extractable nutrients. This study was conducted on seven farms, all of which possessed yield monitor–equipped combines. Field elevation sheets and GPS/GIS technologies were utilized to investigate soil nutrient and yield data for areas of cut and fill at each location. Yields were lower in the cut areas than the fill areas on five of the seven fields. Results from the soil nutrient data were similar to those findings in 1998 and 1999. A nutrient deficiency was apparent in only one of the five fields where yields were reduced. However, the percentage yield loss in the cut areas compared with the fill areas was directly proportional to the volume of soil moved per hectare during the precision land‐leveling process (r2 = 0.78). This research indicates that yields can be reduced after precision land leveling in many soil types, but the reduction may or may not be nutrient related.
Different Techniques to Identify Management Zones Impact Nitrogen and Phosphorus Sampling Variability
Authors: Chang Jiyul , Clay David E. , Carlson Charles G. , Clay Sharon A. , Malo Douglas D. , Berg Robert , Kleinjan Jon , Wiebold William
Published: July 2010

The efficiency of the management zone approach to improve fertilizer recommendations relies on accurately locating zone boundaries. The objective of this study was to determine the impact of different techniques of identifying management zones on soil NO−3–N and Olsen‐P (sodium bicarbonate extractable‐P) sampling variability. Soil samples were collected on a 60 by 60 m or denser grid, in three fields (65, 53, and 40 ha). These samples were analyzed for NO−3–N and Olsen‐P. Soil nutrient data was used to simulate the effect of different techniques to identify P and N management zone boundaries. Approaches evaluated for locating management zone sampling boundaries included: (i) sampling areas impacted by old homesteads or animals separately from the rest of the field; (ii) sampling different grid cells; (iii) use of geographic information systems (GIS) or cluster analysis to identify zones based on apparent electrical conductivity (ECa), elevation, aspect, and distance (connectedness); and (iv) sampling each soil series separately. AnFstatistic was used to determine if the sampling approach reduced nutrient sampling variability. Results suggested that: (i) old homesteads or areas impacted by animals should be sampled separately from the rest of the field; (ii) grid‐cell sampling was more consistent in reducing within zone soil‐test variability than the other techniques tested; and (iii) zones that are not continuous should be sampled and managed separately.
New Indices to Quantify Patterns of Residuals Produced by Model Estimates
Authors: Donatelli Marcello , Acutis Marco , Bellocchi Gianni , Fila Gianni
Published: July 2010

The evaluation of patterns in the residuals of model estimates vs. other variables can be useful in both model evaluation and parameter calibration. New indices that allow quantifying such patterns (pattern indices) are presented. Groups of residuals are created by dividing the range of the variable under evaluation into two, three, four, or five subranges. Two types of indices are proposed. The first type (PI‐type) is based on the absolute value of the maximum difference between pairwise comparisons among average residuals of each group of residuals. A variant of this index is computed by using variance ratios (PI‐F type). The subranges of the variable that determines the grouping of residuals may be of equal length (PI) or variable length (PIν). In the second case, they are generated by an algorithm that optimizes subranges to maximize patterns. The power of the diverse pattern indices at identifying patterns was investigated, and their effectiveness was compared against the runs test. Critical values for pattern indices were generated by Monte Carlo simulations. Monte Carlo probability tables, the results of power analysis, and the results of using pattern indices at two case studies (i.e., daily radiation and soil water content estimates) were presented. The analysis based on pattern indices provided insight in model structure and parameter calibration. Pattern indices also allowed evaluating model performance and discriminating among alternative models. Higher power in identifying patterns was given by range‐based pattern indices than by those based on variance ratios.
Performance of Cows and Their Calves Creep‐Grazed on Rhizoma Perennial Peanut
Authors: Williams M. J. , Chase C. C. , Hammond A. C.
Published: July 2010

Where tropical grasses such as bahiagrass (Paspalum notatum Flügge) make up the base forage, creep‐grazing legumes should be beneficial to calf performance. Treatments of creep with rhizoma perennial peanut (Arachis glabrata Benth.) and no creep were set‐stocked (n = 24, 20, and 32 cow/calf pairs per treatment/replicate combination in 1997, 1998, and 1999, respectively) for an 84‐d grazing period (June–September). Base pasture forage dry matter (DM) availability was similar all 3 yr (avg. 2.81, 2.63, and 3.13 Mg ha−1 for 1997, 1998, and 1999, respectively) and for both treatments (2.84 and 2.87 Mg ha−1 for creep and no creep, respectively). Forage DM availability in the creep areas averaged approximately 3.0 Mg ha−1 and was composed of about 60% grass and 30% rhizoma perennial peanut (RPP). Nutritive value of RPP was usually 60 mg kg−1 higher for crude protein (CP) and 200 mg kg−1 higher for in vitro organic matter disappearance (IVOMD) compared with the associated grass (97.7 mg kg−1 CP and 415.8 mg kg−1 IVOMD). Utilization of creep area varied with year and breed of calf (Angus < 10% vs. Romosinuano > 50%). As a consequence, performance of Angus calves was not affected, but average daily gain (ADG) for Romosinuano calves with access to creep area was higher (+0.14 kg d−1) than that for calves with no creep. Also, body condition score (BCS) that was higher in August and September for creeped‐Romosinuano calves. Creep grazing the calves had no effect on cow performance (weight, ADG, or BCS).
Corn Hybrids for Late Planting in the Southeast
Authors: Wiatrak P. J. , Wright D. L. , Marois J. J. , Sprenkel R.
Published: July 2010

Delayed planting dates in the U.S. Southeast often result in insect and disease problems on corn (Zea mays L.). The objectives of this study were to determine the effects of corn hybrid (type) and planting date on yields and the extent of injury resulting from insects and pathogens. Tropical, Bt (Bacillus thuringiensis var. kurstaki Berliner), and non‐Bt corn hybrids were evaluated for grain and silage yields and insect damage at planting dates from March to August from 1998 to 2001. Averaged across years, corn silage yields were greatest at March and April planting dates (16.1 Mg ha−1) and least from July (6.1 Mg ha−1) and August (4.5 Mg ha−1) planting dates. Silage yields of tropical corn were 26 and 17% higher than non‐Bt and Bt hybrids, respectively, because of less yield reduction at later planting dates. Corn grain yields were greatest at the March planting date (9.6 Mg ha−1) and least at July and August planting dates (0.9 and 0.4 Mg ha−1, respectively). Grain yields of tropical corn were 15 and 10% higher than those of Bt and non‐Bt, respectively. Fall armyworm (Spodoptera frugiperda J.E. Smith), corn earworm (Helicoverpa zea Boddie), and southern corn rust disease (Puccinia polysora Underw.) ratings had negative correlations with corn yields. Insect damage was below 6% for Bt hybrids and above 11% for non‐Bt hybrids. Tropical corn had higher silage and grain yields and better silage quality and disease resistance than either Bt or non‐Bt hybrids.
Characterizing the Environmental Response of a Gibberellic Acid–Deficient Rice for Use as a Model Crop
Authors: Frantz Jonathan M. , Pinnock Derek , Klassen Steve , Bugbee Bruce
Published: July 2010

Rice (Oryza sativa L.) is a useful model crop plant. Rice was the first crop plant to have its complete genome sequenced. Unfortunately, even semidwarf rice cultivars are 60 to 90 cm tall, and large plant populations cannot be grown in the confined volumes of greenhouses and growth chambers. We recently identified an extremely short (20 cm tall) rice line, which is an ideal model for larger rice cultivars. We called this line ‘Super Dwarf’ rice. Here we report the response of Super Dwarf to temperature, photoperiod, photosynthetic photon flux (PPF), and factors that can affect time to head emergence. Vegetative biomass increased 6% per degree Celsius, with increasing temperature from 27 to 31°C. Seed yield decreased by 2% per degree Celsius rise in temperature, and as a result, harvest index decreased from 60 to 54%. The time to heading increased by 2 d for every hour above a 12‐h photoperiod. Yield increased with increasing PPF up to the highest level tested at 1800 μmol m−2 s−1 (12‐h photoperiod; 77.8 mol m−2 d−1). Yield efficiency (grams per mole of photons) increased to 900 μmol m−2 s−1 and then slightly decreased at 1800 μmol m−2 s−1. Heading was delayed by addition of gibberellic acid 3 (GA3) to the root zone but was hastened under mild N stress. Overall, short stature, high yield, high harvest index, and no extraordinary environmental requirements make Super Dwarf rice an excellent model plant for yield studies in controlled environments.
Induction and Inhibition of Striga hermonthica (Del.) Benth. Germination by Extracts of Traditional Chinese Medicinal Herbs
Authors: Ma Y. Q. , Cheng J. M. , Inanaga S. , Shui J. F.
Published: July 2010

Striga hermonthica (Del.) Benth. is a root parasitic weed that reduces the yield of many important cereals in the semiarid tropics in Africa. Yield losses from damage by the parasite are often significant, and complete crop failure is not uncommon. The prolonged use of nonhost plants that produce S. hermonthica germination stimulants may reduce seed reserves in soil over time. The production of high‐value medicinal herbs with S. hermonthica germination induction properties in soils infested with S. hermonthica seed would offer growers an alternative crop as well as potentially reducing S. hermonthica seed reserves. We screened the extracts of 383 traditional Chinese medicinal herbs to test their ability to induce or inhibit the germination of S. hermonthica seeds. Distilled water and methanolic extracts of over 20 herbs induced S. hermonthica germination. Herb extracts that induced S. hermonthica germination rates greater than 50% were Acorus gramineus Soland., Agrimonia pilosa Ledeb. var. japonica (Miq.) Nakai, Areca catechu L., Citrus tangerina Hort. et Tanaka, Cudrania cochinchinensis (Lour.) Kudo et Masam., Nardostachys chinensis Batal., Oldenlandia diffusa (Wild.) Roxb., Portulaca oleracea L., Scrophularia ningpoensis Hemsl., and Semiaquilegia adoxoides (DC.) Mak. Water extracts from 27 herbs inhibited S. hermonthica germination. The undiluted extract from Curcuma longa L. completely inhibited S. hermonthica germination. Undiluted extracts from 15 other herbs reduced germination by more than 50% compared with the positive control. The results from this study indicate that metabolites produced by some traditional medicinal herbs may have the potential to be used as bioherbicides to control S. hermonthica.
Influence of Certain Postemergence Broadleaf Herbicides on Soybean Stressed from Iron Deficiency Chlorosis
Authors: Franzen D. W. , O’Barr J. H. , Zollinger R. K.
Published: July 2010

Postemergence herbicides are widely used in soybean [Glycine max(L.) Merr.]. Although yield is seldom reduced following herbicide applications to soybean under normal growing conditions, little is known regarding their application when the crop is under stress. Iron deficiency chlorosis (IDC) is a common problem in the Red River Valley of North Dakota and Minnesota. Postemergence herbicide applications are usually made early in the season when IDC is most expressed. The objective of this experiment was to compare the effects of selected postemergence soybean herbicides applied to soybean under stress from IDC. Treatments were applied at 12 locations during a 3‐yr study. Stunting and necrosis were evaluated at 14 and 28 d after treatment (DAT), and plots were harvested to determine grain yield. There were treatment differences in stunting at 11 locations 14 DAT and at nine locations 28 DAT. Differences in leaf necrosis were found among treatments at 11 locations 14 DAT and at four locations 28 DAT. Lactofen significantly lowered yield at six locations, and imazamox and imazethapyr lowered yield at three locations. These results suggest that herbicides with harsh contact activity (lactofen) and some acetolactate synthase (ALS) inhibitors (e.g., imazamox, thifensulfuron, and imazethapyr) may have potential for greater injury under these soil and environmental conditions. It may be important to consider herbicide injury effects, in addition to weed spectrum, when selecting herbicides for use on IDC‐stressed soybean.
Soil Surface Property and Soybean Yield Response to Corn Stover Grazing
Authors: Clark Justin T. , Russell James R. , Karlen Douglas L. , Singleton P. L. , Darrell Busby W. , Peterson Brian C.
Published: July 2010

Farmer concern that compaction and/or surface roughness caused by winter grazing of corn (Zea mays L.) crop residues may reduce subsequent soybean [Glycine max (L.) Merr.] yield prompted this 3‐yr, on‐farm study near Atlantic, IA. Two 19‐ha fields with Marshall silty clay loam (fine‐silty, mixed, superactive, mesic Typic Hapludolls), Minden silty clay loam (fine‐silty, mixed, superactive, mesic Aquic Hapludolls), Corley silt loam (fine‐silty, mixed, superactive, mesic Argiaquic Argialbolls), and Colo silty clay loam (fine‐silty, mixed, superactive, mesic Cumulic Endoaquolls) soils managed in a corn–soybean rotation were chisel‐plowed and split into four replicate blocks of six paddocks. Five paddocks within each block were grazed in consecutive 4‐wk intervals at a stocking rate of 3.7 cows ha−1 while the sixth provided a nongrazed control. Following each grazing season, two blocks were disked, and two received no‐tillage before soybean planting. Soil bulk density, aggregate stability, moisture content, penetration resistance, surface roughness, residue cover, soybean plant population, and yield were evaluated for each grazing by tillage treatment. Soil bulk density was not affected, but penetration resistance to a depth of 10 cm increased in paddocks grazed in October and November. Cattle grazing had no effect on subsequent soybean plant population, but yield decreased with increased soil penetration resistance (r2 = 0.36). As the proportion of time soil temperature was below 0°C during the grazing period increased, soybean yield increased (r2 = 0.72). Effects of grazing corn crop residues on subsequent soybean yield will be minimal if grazing is restricted to periods when soils are frozen or if the soil is disked before soybean planting.
Repeated Biomass Removal Affects Soybean Resource Utilization and Yield
Authors: Singer Jeremy W. , Meek David W.
Published: July 2010

Soybean [Glycine max (L.) Merr.] producers in many regions of the USA are confronted with significant yield losses because of crop damage from white‐tailed deer (Odocoileus virginianus). Our objectives were to quantify soybean resource utilization and yield responses to variety, row spacing, and simulated repeated biomass removal. Field research was conducted in 2000 and 2001 on a Quakertown silt loam soil (fine‐loamy, mixed, mesic Typic Hapludult) near Pittstown, NJ. Biomass removal during early vegetative and vegetative/reproductive growth extended the soil wetness duration index on average by 1.5 and 2.9 d compared with the control from the 0‐ to 30‐ and 30‐ to 60‐cm soil depths in 2000 and by 5.1 and 2.1 d in 2001. Biomass removal during early vegetative growth delayed pod maturity up to 7 d compared with the control, but biomass removal during reproductive growth hastened pod maturity by as much as 3 d. Averaged across row spacing and biomass removal, variety ‘APK394NRR’ yielded 12 and 24% lower than ‘93B53’ in 2000 and 2001. In 2000, averaged across variety and biomass removal, the 20‐ and 41‐cm row widths yielded 19 and 16% less than the 76‐cm row width. Averaged across variety and row spacing, all biomass removal treatments lowered yield compared with the control except the midvegetative/early reproductive treatment in 2001 (661 vs. 663 g m−2). The greatest yield reductions occurred (up to 89%) when biomass was removed repeatedly during vegetative and reproductive growth. Management implications for soybean producers include variety selection and row spacing to diminish the effects of deer damage.
Evaluation of Crop Rotation and Other Cultural Practices for Management of Root‐Knot and Lesion Nematodes
Authors: Kratochvil Robert J. , Sardanelli Sandra , Everts Kathryne , Gallagher Elizabeth
Published: July 2010

Root‐knot [Meloidogyne incognita (Kofoid & White) Chitwood] and lesion [Pratylenchus penetrans (Cobb) Chitwood & Oteifa] nematodes are important pathogens that cause yield and quality losses for most vegetable and field crops in Maryland when they exceed certain threshold levels and if control measures are not applied. Chemical nematicides are the primary control tactic, but their use is both costly and raises environmental concerns. This study was conducted to evaluate the efficacy of crop rotation and other cultural practices for management of southern root‐knot nematodes (RKNs) and lesion nematodes. Three nonhost crops, a RKN‐resistant soybean [Glycine max (L.) Merr.] cultivar, and poultry litter/tillage (Year 1) and fallow (Year 2) were used as summer rotation crops/management options following production of nematode‐susceptible crops on two sites in Dorchester County, MD, on Downer and Hammonton sandy loam soils (coarse‐loamy, siliceous, mesic Typic and Aquic Hapludults), respectively. Sorghum sudangrass [Sorghum bicolor (L.) × S. arundinaceum (Desv.) Stapf var. sudanense (Stapf) Hitchc.], grown annually as a green manure crop following a nematode‐susceptible crop [potato (Solanum tuberosum L.) or cucumber (Cucumis sativus L.)], reduced the RKN population as effectively as the control treatment (soybean cultivar with no known RKN resistance and one nematicide application). Sorghum sudangrass and poultry litter/tillage/fallow were equally effective in managing the lesion nematode population. Annual inclusion of these practices was necessary to maintain the reduced population levels that were attained for these two nematode species. Finally, either summer or early‐fall sampling dates were determined to be more effective than a midspring sampling date for identifying threshold levels of these two pests.
Corn Response to Within Row Plant Spacing Variation
Authors: Lauer Joseph G. , Rankin Mike
Published: July 2010

Recent interest in establishing uniform spacing of corn (Zea mays L.) plants in the field has prompted many seed companies to offer planter‐tuning services. Experiments were conducted in Wisconsin environments between 1999 and 2001 to investigate the response of corn to plant spacing variation (PSV). During 1999, adapted hybrids were grown in the field by overseeding and thinning to 37000 and 74000 plants ha−1 in a two‐plant pattern with target PSV treatments of 0, 10.2, 20.3, and 30.5 cm and 0, 2.5, 5.1, 7.6, 10.2, and 12.7 cm, respectively. During 2000 and 2001, two‐, four‐, and eight‐plant “hill” patterns were established with target PSV treatments of 5.1 and 10.2 cm; 5.1, 10.2, and 20.3 cm; 5.1 10.2, 20.3, and 30.5 cm standard deviation. The control treatment was a target PSV of 0 cm. In this study, PSV never affected plant lodging or grain test weight. In one of 24 environments grain moisture was significantly affected, but no relationship was observed with PSV. Grain yield was rarely affected by PSV in two‐plant patterns. Relative grain yield was reduced up to 18% as plant spacing became more “hill‐like” in two‐, four‐, and eight‐plant patterns. Relative grain yield was reduced 1.06% cm−1 standard deviation as PSV increased above 12.0 cm. However, for most farmer field situations at current plant density recommendations, corn grain yield would not be affected by PSV, except when obvious hills are planted.
Nutrient Uptake of Hybrid and Common Bermudagrass Fertilized with Broiler Litter
Authors: Brink G. E. , Sistani K. R. , Rowe D. E.
Published: July 2010

Among forage crops utilized in the southeastern USA, bermudagrass [Cynodon dactylon (L.) Pers.] has the greatest potential to recover nutrients from soil routinely fertilized with broiler litter due to its yield potential and wide adaptation. Our objective was to determine differences in N and P uptake among diverse bermudagrass cultivars fertilized with broiler litter. ‘Alicia’, ‘Brazos’, ‘Coastal’, ‘Russell’, ‘Tifton 44’, and ‘Tifton 85’ hybrid bermudagrass and common bermudagrass were grown on a Savannah fine sandy loam (fine‐loamy, siliceous, semiactive, thermic Typic Fragiudult) and fertilized with 11.8 Mg litter dry matter (DM) ha−1 yr−1 (15.75 Mg as‐is basis) to provide 540 kg total N ha−1 yr−1 and 330 kg total P ha−1 yr−1 (mean of 4 yr). Alicia, Coastal, and Russell had similar annual yield in 3 of 4 yr, but yield differences among other hybrids were not consistent. Although annual N and P uptake of common bermudagrass was equivalent to Alicia, Coastal, and Tifton 44 during 2 yr due primarily to greater herbage N and P concentration, reduced uptake in years of below‐normal precipitation indicates it is not an acceptable alternative to a hybrid. No differences in N uptake existed among a majority of hybrids when precipitation was near normal, and Alicia, Coastal, and Russell had equivalent N uptake all 4 yr. Nitrogen and P uptake of Tifton 85 increased each year and, by the final year of the study, exceeded that of all cultivars. Among all the hybrids, only Russell exhibited consistent superior P uptake relative to Coastal.
Identification of Relationships between Cotton Yield, Quality, and Soil Properties
Authors: Ping J. L. , Green C. J. , Bronson K. F. , Zartman R. E. , Dobermann A.
Published: July 2010

Intercorrelation among soil properties can result in multicollinearity problems regarding relationships between soil properties and crop yield. The objective of this study was to compare statistical methods of examining relationships between cotton (Gossypium hirsutumL.) yield, quality, and soil properties. Soil and plant samples were collected from 1‐ha grids on an irrigated production cotton field in Texas from 1998 through 2000. Ordinary least square regression (OLS), partial least square regression (PLS), and principal component regression (PCR) were compared as methods for quantifying relationships between cotton yield or quality and soil properties. The PLS method eliminated multicollinearity problems and resulted in the coefficient estimations with meaningful signs compared with their associations to cotton yield and fiber quality. Furthermore, loadings from linear combinations of variables in PLS allowed identifying soil properties that had the greatest influence on yield. While PCR identified the principal components that maximized the variance of independent variables, it did not improve the modeling of crop–soil relationships. Among the selected soil and landscape properties, sand and clay content, exchangeable Ca2+and Mg2+, NO3−, Olsen‐P, pH, relative elevation, and slope were important factors affecting lint yield and fiber quality. Higher lint yields were usually accompanied by higher fiber quality. Magnitudes of influence of different soil properties on yield and quality, however, varied among the 3 yr, suggesting that long‐term studies are needed to establish robust relationships for site‐specific management.