Row Lengths Research Articles

The effect of a tandem vane crossover diffuser configuration on the performance of a MGT mixed flow compressor

Due to the inherent geometric restrictions of a micro gas turbine (MGT) mixed flow compressor design, diffuser design has a major impact on compressor performance and operating range. Vaned diffusers are often preferred to vaneless diffusers in MGT compressor designs due to better efficiency and pressure recovery, albeit at the expense of operating range. A numeric investigation of the effect of a tandem vane crossover diffuser configuration on the performance and operating range of a MGT mixed flow compressor stage is presented. Three baseline test compressors, covering a wide range of design speeds, mass flow rates and meridional exit angles, are designed with a single vane crossover diffuser. For each of the three baseline compressors, the crossover diffuser design is modified to feature various tandem vane configurations. The tangential shift of the second vane row relative to the first row is evaluated. Additionally, relative first and second vane row lengths are evaluated. The performance (efficiency and pressure ratio) and operating range of the modified diffuser configurations are compared to the baseline configurations. It is shown that a 75% second vane row tangential shift configuration displays the best overall performance, regardless of the relative vane length. It is further shown that an appropriate vane length depends on the design requirement.

Elevated evolutionary rates of biting biomechanics reveal patterns of extraordinary craniodental adaptations in some herbivorous dinosaurs

AbstractAdaptation to specialist ecological niches is a key innovation that has contributed to the evolutionary success of many vertebrate clades, underpinning the acquisition of diverse skull morphologies. Dinosaurs, which dominated Mesozoic terrestrial faunas, acquired herbivory multiple times, and evolution of these herbivorous adaptations is linked to drastic changes in dental and craniomandibular functional morphology, yet whether changes in functionally relevant phenotypic traits occurred more rapidly in herbivorous lineages compared to in carnivorous lineages remains largely untested in a statistical phylogenetic framework. Here, we infer rates of phenotypic evolution using phylogenetic variable‐rate models on relative biting edge (tooth row) lengths of 107 dinosaur taxa to test the hypothesis that the acquisition of herbivory is associated with rapid changes in mandibular biomechanics. We find elevated rates of biomechanical evolution in theropods with foreshortened and beaked skulls (Oviraptorosauria, Limusaurus), as well as in ceratopsians and Diplodocus. The presence and position of a reduced tooth row and increased jaw efficiency unite these high‐rate lineages, indicating selection for greater efficiency in biting biomechanics. Large departures from the isometric scaling of these mandibular characteristics helps explain the differences in evolutionary rates in these clades and those of other herbivorous theropods (Therizinosauria, Ornithomimosauria). Additionally, we hypothesize that extreme ontogenetic changes within species lifetimes may be behind some instances of branch‐wise elevated rates. Thus, we show how exceptional rates of biomechanical evolution can reveal signatures of ecological adaptations within dinosaur lineages as well as within‐species ontogenetic sequences.

Maize Growth and Grain Yield Responses to a Micronized Humic Product Across Soil Types and Annual Weather Patterns in Central Iowa, United States.

Despite growing interest in humic products as crop amendments, very few field evaluations have considered environmental factors of humic product efficacy. We determined the spatial and temporal variability in the efficacy of a micronized humic product on maize (Zea mays L.) growth and grain yield in two rainfed fields supporting a maize−soybean [Glycine max (L.) Merr.] rotation in 2012–2014, and 2016 in central Iowa, U.S. Crop management in both fields otherwise followed conventional farmer practices. In two dry growing seasons, mechanized combine measurements of grain yield increased significantly (P < 0.10) with humic product application on an eroded hilltop soil, amounting for two application rates to 930 and 1,600 kg ha–1 (11 and 19% of the control grain yield) in 2012, the droughtiest season, and 700 kg ha–1 (7% of the control) for the higher application rate in the somewhat droughty 2013 season. On a fertile side slope soil in the 2012 field, though, only a faint numeric response occurred in 2012, while on a toe slope soil the sole significant increase was in 2012, 870 kg ha–1 (14% increase above the control) for one application rate. With favorable rainfall in 2014 and 2016, significant grain yield increases with product application were small in the upland soil of 2014 and absent in 2016. Yield components analysis on 1-m row lengths of hand-collected samples attributed these yield boosts primarily to increased ear length, especially of the shorter ears. Combine grain yields, yield components, and total leaf area all demonstrated numerically slightly greater values for humic product treatments compared to the control in the vast majority of comparisons across years and soil types, with better distinction in the upland transects. Statistical significance, though, was reached only in the droughtier settings. The humic product had no consistent effects on nutrient concentrations of the grain, stover, or young leaves. Grain quality parameters showed a slight shift from protein to carbohydrates in the droughtier settings. Fifteen soil properties showed no response to the humic product. This humic product demonstrated the capability to improve maize growth in rainfed conditions in a high-yielding region, and its efficacy varied predictably with environmental conditions. This finding provides one potential explanation for inconsistent reports elsewhere of crop responses to humic products.

INCREASING THE EFFICIENCY OF SURFACE IRRIGATION BY USING SURGE IRRIGATION FOR COTTON PRODUCTION IN THE DELTA SOILS

Two field experiments were conduct at Sakha Agricultural Research Station at Kafr El-Sheikh Governorate, Egypt, during 2018 and 2019 seasons to study increasing the efficiency of surface irrigation by using surge irrigation for cotton production in the Delta soils for Giza 96 cotton variety. A split plots design with four replications was used, where the main plots involved three lengths of irrigation rows (30, 40 and 50 meter) and the sub plots included three surge irrigation timing systems (time for opening and closing surge irrigation) (10 minute open -10 minute close, 15 minute open -15 minute close and 20 minute open -20 minute close until finish from irrigation). The results indicated that; The 30 meter row length irrigation significantly increased p lant height, no. of fruiting branches/plant, number of open bolls /plant, boll weight, seed cotton yield/plant and seed cotton yield/fed. compared with the other treatments irrigation row lengths 40 and 50 meter. The surge irrigation timing system 10 minutes open and 10 minutes close significantly increased plant height, number of fruiting branches/plant, number of open bolls/plant, boll weight, seed cotton yield/plant and seed cotton yield/fed. compared with the other surge irrigation timing systems (15-15 and 20-20). The interaction between 30 meter row length and surge irrigation timing system 10 minutes open and 10 minutes close gave the good values of growth, yield and its components of Giza 96 cotton variety in both seasons. Row lengths irrigation and surge irrigation timing systems treatments and its interaction did not exhibit any significant effect on seed index, lint % and fiber properties in both seasons. Finally, using 30 meter irrigation row length and surge irrigation timing systems 10 minutes open and 10 minutes close gave the highest seed cotton yield/fed. for Giza 96 cotton cultivar under the conditions of Kafr El-Sheikh in the Delta soils.

Classifying the near-equality of ribbon Schur functions

We consider the problem of determining when the difference of two ribbon Schur functions is a single Schur function. We fully classify the five infinite families of pairs of ribbon Schur functions whose difference is a single Schur function with corresponding partition having at most two parts at least 2. We also prove an identity for differences of ribbon Schur functions and we determine some necessary conditions for such a difference to be Schur-positive, depending on the distribution of 1’s and the end row lengths.

Hecke insertion and maximal increasing and decreasing sequences in fillings of stack polyominoes

We prove that the number of 01-fillings of a given stack polyomino (a polyomino with justified rows whose lengths form a unimodal sequence) with at most one 1 per column which do not contain a fixed-size northeast chain and a fixed-size southeast chain, depends only on the set of row lengths of the polyomino. The proof is via a bijection between fillings of stack polyominoes which differ only in the position of one row and uses the Hecke insertion algorithm by Buch, Kresch, Shimozono, Tamvakis, and Yong and the jeu de taquin for increasing tableaux of Thomas and Yong. Moreover, our bijection gives another proof of the result by Chen, Guo, and Pang that the crossing number and the nesting number have a symmetric joint distribution over linked partitions.

Large Deviations and One-Sided Scaling Limit of Randomized Multicolor Box-Ball System

The basic $\kappa$-color box-ball (BBS) system is an integrable cellular automaton on one dimensional lattice whose local states take $\{0,1,\cdots,\kappa \}$ with $0$ regarded as an empty box. The time evolution is defined by a combinatorial rule of quantum group theoretical origin, and the complete set of conserved quantities is given by a $\kappa$-tuple of Young diagrams. In the randomized BBS, a probability distribution on $\{0,1,\cdots,\kappa \}$ to independently fill the consecutive $n$ sites in the initial state induces a highly nontrivial probability measure on the $\kappa$-tuple of those invariant Young diagrams. In a recent work \cite{kuniba2018randomized}, their large $n$ `equilibrium shape' has been determined in terms of Schur polynomials by a Markov chain method and also by a very different approach of Thermodynamic Bethe Ansatz (TBA). In this paper, we establish a large deviations principle for the row lengths of the invariant Young diagrams. As a corollary, they are shown to converge almost surely to the equilibrium shape at an exponential rate. We also refine the TBA analysis and obtain the exact scaling form of the vacancy, the row length and the column multiplicity, which exhibit nontrivial factorization in a one-parameter specialization.

Support Equalities Among Ribbon Schur Functions

In 2007, McNamara proved that two skew shapes can have the same Schur support only if they have the same number of $k \times \ell$ rectangles as subdiagrams. This implies that two ribbons can have the same Schur support only if one is obtained by permuting row lengths of the other. We present substantial progress towards classifying when a permutation $\pi \in S_m$ of row lengths of a ribbon $\alpha$ produces a ribbon $\alpha_{\pi}$ with the same Schur support as $\alpha$; when this occurs for all $\pi \in S_m$, we say that $\alpha$ has full equivalence class. Our main results include a sufficient condition for a ribbon $\alpha$ to have full equivalence class. Additionally, we prove a separate necessary condition, which we conjecture to be sufficient.

Characteristics of the transverse 2D uniserial arrangement of rows of decussating enamel rods in the inner enamel layer of mouse mandibular incisors.

The 2D arrangement of rows of enamel rods with alternating (decussating) tilt angles across the thickness of the inner layer in rat and mouse incisor enamel is well known and assumed to occur in a uniform and repetitive pattern. Some irregularities in the arrangement of rows have been reported, but no detailed investigation of row structure across the entire inner enamel layer currently exists. This investigation was undertaken to determine if the global row pattern in mouse mandibular incisor enamel is predominately regular in nature with only occasional anomalies or if rows of enamel rods have more spatial complexity than previously suspected. The data from this investigation indicate that rows of enamel rods are highly variable in length and have complex transverse arrangements across the width and thickness of the inner enamel layer. The majority of rows are short or medium in length, with 87% having < 100 rods per row. The remaining 13% are long rows (with 100–233 rods per row) that contain 46% of all enamel rods seen in transverse sections. Variable numbers of rows were associated with the lateral, central and mesial regions of the enamel layer. Each region contained different ratios of short, medium and long rows. A variety of relationships was found along the transverse length of rows in each region, including uniform associations of alternating rod tilts between neighboring rows, and instances where two rows having the same rod tilt were paired for variable distances then moved apart to accommodate rows of opposite tilt. Sometimes a row appeared to branch into two rows with the same tilt, or conversely where two rows merged into one row depending upon the mesial‐to‐lateral direction in which the row was viewed. Some rows showed both pairing and branching/merging along their length. These tended to be among the longest rows identified, and they often crossed the central region with extensions into the lateral and mesial regions. The most frequent row arrangement was a row of petite length nestled at the side of another row having the same rod tilt (30% of all rows). These were termed ‘focal stacks’ and may relate to the evolution of uniserial rat and mouse incisor enamel from a multilayered ancestor. The mesial and lateral endpoints of rows also showed complex arrangements with the dentinoenamel junction (DEJ), the inner enamel layer itself, and the boundary area to the outer enamel layer. It was concluded that the diversity in row lengths and various spatial arrangements both within and between rows across the transverse plane provides a method to interlock the enamel layer across each region and keep the enamel layer compact relative to the curving DEJ surface. The uniserial pattern for rows in mouse mandibular incisors is not uniform, but diverse and very complex.

ECONOMIC ANALYSIS OF DIFFERENT HYDRAULIC SPRAYERS USED IN SUGARCANE (Saccharum spp.)

ABSTRACT Brazil is the largest sugarcane producer worldwide. In mills, sugarcane crops are sprayed with agrochemicals using self-propelled, tractor-driven, and aerial hydraulic sprayers. As sugarcane spraying is regularly performed over extensive areas, the machinery to be used should be planned and dimensioned to ensure timely operations without overloading and at lower costs. Therefore, the current study aimed to analyze the operational and economic performances of different hydraulic sprayers to perform sugarcane crop control. As long as meeting our goal in field conditions would be difficult, we opted to develop a computational model, named as “TratoCana”, using a spreadsheet and programming language. The model was used to assess economic and operational factors by generating scenarios and analyzing probable routine errors. In short, the results evidenced that initial value and operation speed are factors with the strongest impact on the costs of self-propelled sprayers and tractor-sprayer sets. Yet, the aerial application was mostly affected by fuel costs and crop row lengths. Moreover, the larger the spray tank volume, the lower the costs.

On the number of terms in the Lovelock products

In this short note we wonder about the explicit expression of the expanding of the p-th Lovelock product. We use the 1990s’ works of S. A. Fulling et al. on the symmetries of the Riemann tensor, and we show that the number of independent scalars appearing in this expanding is equal to the number of Young diagrams with all row lengths even in the decomposition of the p-th plethysm of the Young diagram representing the symmetries of the Riemann tensor.

Design-Unbiased Estimation and Alternatives for Sampling Trees on Plantation Rows

Recently, methods for inventories of forest plantations have been proposed based on the use of remote sensing to estimate total row length, followed by the estimation of plantation row attributes, such as number and volume or weight of trees, at randomly selected field locations on the ground within a forest plantation of interest. While we are aware of instances in which such inventories have been performed, to our knowledge, no scientific studies of this approach have previously appeared. Many plantation inventories have been performed by traditional methods, such as Bitterlich (point) sampling and fixed-size plot sampling. Random plot sizes including a fixed number of rows are possible but the resulting estimators are typically not unbiased. Plot sampling and Bitterlich sampling can be problematic in plantations because inventory crews may gravitate towards the establishment of sample points in similar locations relative to row spacing, e.g., midway between rows, compromising the assumption of random point location in the tract area. We propose and test five novel estimators which are based on sampling a fixed number of trees at random sample locations on rows. The methods we propose can be used to estimate tract-level quantities of any tree attribute, including the number of trees, total volume, basal area, and others. Fixed row lengths may be sampled at randomly determined field locations on rows. Alternatively, distance sampling methods can be used to sample a fixed number of trees subsequent to, or nearest to, a randomly located point on a plantation row. Ducey’s recently-developed estimator for point-to-particle sampling on lines can be applied to sampling on rows. A “mean of ratios” (MR) estimator can be based on the average ratio of the sum of the sample trees’ attributes divided by the length of line occupied by the sample trees. A “ratio of means” (RM) estimator can be based on the ratio of the mean of the sample trees’ attributes for all random points divided by the mean sample line length for all random points. For either of these ratio estimators, the line length may be chosen to include the gap between trees into which the random sample point falls (G-MR, mean of ratios including the sample gap and G-RM, ratio of means estimator including the sample gap), or it may be chosen to begin subsequent to that gap (NG-MR, mean of ratios not including the sample gap and NG-RM, ratio of means not including the sample gap). A simulation was used to test each of these techniques on typical plantation row populations. Two row populations were used in the simulation. One had relatively uniform spacing between trees on a row, which resembles the characteristics of young plantations. The second population contained numerous gaps, typical of more mature plantations that have been thinned and may be experiencing mortality. In the simulations, the estimators were used to estimate the number of trees in each population. Trends in other variables, such as volume or basal area, were similar to those for te estimated number of trees in the populations. The simulation results showed that the G-MR method had the smallest root mean square error followed by the NG-RM. Ducey’s method and the fixed-length row plot were both design-unbiased. Both the latter methods had low root mean square errors but these were slightly higher than some of the other methods. In contrast to the other methods tested, the NG-MR and G-RM methods were both substantially biased on a simulated row population containing large gaps which might occur due to mortality or thinning. The estimators which had good performance in simulations—Ducey’s method, G-MR, NG-RM, and fixed-length row sampling—are viable alternatives to traditional methods of sampling plantations, such as Bitterlich sampling and fixed-size plot sampling, if accurate plantation row lengths can be measured.

Necessary Conditions for Schur-Maximality

McNamara and Pylyavskyy conjectured precisely which connected skew shapes are maximal in the Schur-positivity order, which says that $B\leq _s A$ if $s_A-s_B$ is Schur-positive. Towards this, McNamara and van Willigenburg proved that it suffices to study equitable ribbons, namely ribbons whose row lengths are all of length $a$ or $(a+1)$ for $a\geq 2$. In this paper we confirm the conjecture of McNamara and Pylyavskyy in all cases where the comparable equitable ribbons form a chain. We also confirm a conjecture of McNamara and van Willigenburg regarding which equitable ribbons in general are minimal. Additionally, we establish two sufficient conditions for the difference of two ribbons to be Schur-positive, which manifest as diagrammatic operations on ribbons. We also deduce two necessary conditions for the difference of two equitable ribbons to be Schur-positive that rely on rows of length $a$ being at the end, or on rows of length $(a+1)$ being evenly distributed.

Late Quaternary Subfossils of Forest Rats (Tokudaia muenninkiandDiplothrix legata) and Other Small Mammals Found in the Sashiki Fissure on Okinawajima of the Ryukyu Archipelago, Japan

This study presents the late Quaternary faunal change of small mammals on the southern part of Okinawajima (Ryukyu Archipelago) on the basis of subfossils in late Pleistocene and middle Holocene fissure-filling deposits. The present subfossils include the Okinawa spiny rat Tokudaia muenninki, Ryukyu long-furred rat Diplothrix legata, Watase's shrew Crocidura watasei, and an indeterminate species of bat. With the exception of C. watasei, these species no longer exist in southern Okinawajima. Predominance of these rat species suggests that the environment around the fissure was densely forested during these ages. However, the presence of C. watasei remains implies that open habitats also existed in the middle Holocene. Tokudaia muenninki remains from the fissure show that it had survived on southern Okinawajima until the middle Holocene. The upper first molar widths and lower molar row lengths in the late Pleistocene T. muenninki material from the fissure are significantly smaller than those of extant conspecific specimens, whereas the upper molar row length appears to be similar to those of the extant conspecifics. These findings suggest that the molar proportions of T. muenninki have changed since the late Pleistocene.

Matrix product construction for Koornwinder polynomials and fluctuations of the current in the open ASEP

Starting from the deformed current-counting transition matrix for the open boundary ASEP, we prove that with a further deformation, the symmetric Koornwinder polynomials for partitions with equal row lengths appear as the normalisation of the twice deformed ground state. We give a matrix product construction for this ground state and the corresponding symmetric Koornwinder polynomials. Based on the form of this construction and numerical evidence, we conjecture a relation between the generating function of the cumulants of the current, and a certain limit of the symmetric Koornwinder polynomials.

The effect of row grade and length on soil erosion from concentrated flow in furrows of contouring ridge systems

Concentrated flow in furrows may lead to serious rill erosion in production systems where ridges are mulched with plastic film in contouring ridges. Studying the effect of influential factors on soil erosion in such systems could improve our understanding on erosion process and take appropriate control treatments. Considering a furrow with mulched ridges on both sides as a width-limited eroding rill, an in situ field experiment was conducted to analyze the effect of row grades and row lengths on soil erosion. Soil erosion indices, including runoff, runoff modulus, sediment concentration, soil loss, and soil loss modulus were monitored. Row grade and length exerted significant effect on all indices at p<0.01. The relationship of sediment concentration, soil loss, soil loss modulus and row grade could be fitted by exponential functions (R2>0.950, p<0.01) with the exponents expressed as second-order polynomial functions. From the convex curves of these exponential functions, the critical row grade at which the maximum values occurred were interpreted as 10%. With row grade increasing, erosion presented a detachment-limited process. The relationship between row length and soil erosion indices could be modeled by different exponential functions (R2>0.830, p<0.01): two-parameter exponential function for runoff, modulus of runoff and modulus of soil loss; Box Lucas model for sediment concentration; and second-order polynomial function for soil loss. Based on the results, we suggest that avoiding the row grade of 10% and row length <5m could reduce soil loss in the contouring ridges where plastic film covers ridges and irrigation is used to supply water into furrows.

Systematic reassessment of an agriochoerid oreodont from the Hancock Mammal Quarry, Clarno (Eocene, Duchesnean), Oregon

ABSTRACTThe 31 crania of the agriochoerid oreodont from the Hancock Mammal Quarry (HMQ) possess character states unique among described agriochoerid species. Characters unique to the HMQ agriochoerid include a triangular P2; a P3 with a posterolingual cone and heart-shaped occlusal outline; a P4 with separate anterolabial and posterolabial cones, but without a posterolingual conule; upper molars with large styles and lacking paraconules; lower molars without lingual cingulids, but possessing small metastylids and parastylids; and a mandibular symphysis that is perpendicular to the tooth row without ventral displacement of the p1. We subjected previous size comparisons to an F-test and Welch's t-test and found that the tooth row lengths of the HMQ agriochoerid have significantly different variance and means from Agriochoeus matthewi crassus (P = .005), a taxon to which this population has previously been assigned. Taken together, these characters are diagnostic of a new species, which we describe here as Diplobunops kardoula. The HMQ specimens show that some of the diagnostic dental characters of agriochoerids currently in use change with wear and may be biased by taphonomy. Furthermore, characters diagnostic of both Agriochoerus and Diplobunops are present in the HMQ agriochoerid, and many of the species-level diagnostic characters of agriochoerids are continuously variable or polymorphic within the HMQ population.http://zoobank.org/urn:lsid:zoobank.org:pub:1731B5C5-0C56-486A-8B46-46396F26EEF5SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVPCitation for this article: Emery, M. M., E. B. Davis, and S. S. B. Hopkins. 2015. Systematic reassessment of an agriochoerid oreodont from the Hancock Mammal Quarry, Clarno (Eocene, Duchesnean), Oregon. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2015.1041970.

Yet another Hybrid Strategy for Auto-tuning SpMV on GPUs

Sparse matrix-vector multiplication (SpMV) is a key linear algebra algorithm and is widely used in many application domains. Besides multi-core architecture, there is also extensive research focusing on accelerating SpMV on many-core Graphics Processing Units (GPUs). SpMV computations have many indirect and irregular memory accesses, and load imbalance could occur while mapping computations onto single-instruction, multiple-data (SIMD) GPUs. SpMV is highly memory bandwidth-bound, though GPUs have massive computational resources, the performance of SpMV on GPUs is still unsatisfying. In this paper, we present a new hybrid strategy for auto-tuning SpMV on GPUs. Our strategy combines the advantages of row-major storage and column-major storage. Like many other strategies, we reordered a given sparse matrix according to row lengths in decreasing order. In order to be more adaptive and efficient, we proposed a new hybrid Blocked CSR and JDS (BCJ) format based on original CSR and JDS. BCJ splits a sparse matrix into a denser part and a sparser part after reordering and uses different kernels to process the corresponding part. And we proposed corresponding auto-tuning framework to help transforming matrix and launching kernels according to the sparsity characteristics of the matrix. A CUDA implementation of BCJ outperforms the original formats significantly on a broad range of unstructured sparse matrices.

Cost of boundary manoeuvres in sugarcane production

Machinery has direct and indirect costs associated with their work in field, with non-productive time spent in manoeuvres when machinery reaches field borders. Much work has been carried reducing the number of manoeuvres in complex field shapes and changing the type of manoeuvre in order to speed them up. Biofuel producing crops such as sugarcane (Saccharum spp.) besides requiring economic profitability demand positive energy output in their production chain. Sugarcane uses narrow width equipment which requires time-costly manoeuvres adding significant inputs particularly on short rows. Using a method and calculations that is applicable for other crops, this study takes operational, spatial, economic, and energy factors into account to observe the impact of manoeuvres at the headland of a sugarcane crop. Energy and economic costs were retrieved from the hourly use of machines for four main field operations and their respective manoeuvring costs. Crop parameters were retrieved with their data compared with operational costs to establish the dimensions of row-length benefits. Increases in row length and width has decreasing benefits that may conflict with the logistics of servicing auxiliary units. The impacts of turning patterns were obtained, it suggests changes to minimise time and space for manoeuvring in planting and cultivating operations, and using wider roads and more steerable carriers in harvesting operations. In standard scenarios of a production system it was found that the income from row lengths less than 50 m were less than the economic costs occurred in turning at the headland.

Nontarget Deposition and Losses of Chlorothalonil in Irrigation Runoff Water from a Commercial Foliage Plant Nursery

Commercial foliage plant production requires the use of pesticides for controlling pests and pathogens that can reduce aesthetic qualities of crops, rendering them unwanted by consumers. Chlorothalonil is a common, broad-spectrum, foliar fungicide used for protecting plants from a variety of fungal diseases. This fungicide may also be acutely toxic to nontarget aquatic organisms due to its mode of action. This study evaluated the amount of chlorothalonil deposited on nontarget ground surfaces during normal sprayer applications at a commercial nursery using Teflon targets. One day following application, irrigation runoff events were initiated and runoff water samples were collected and analyzed for chlorothalonil. Discharge volumes were also measured to allow estimation of the total mass of chlorothalonil discharged during each event. Results indicated that 9.8 to 53.6% of the active ingredient applied landed on nontarget ground surfaces depending on plant size, spacing, and row lengths (short rows sprayed from one side vs. longer rows sprayed from both ends). On an entire production-area scale, 29.2% of the active ingredient applied was deposited on ground surfaces. Of the total nontarget deposition, 0.25 to 0.53% was detected in runoff water discharged from the production area. Concentrations ranged from 1.2 to 500 microg/L during the first runoff events following application.