Broadcast Applications Research Articles

Ammonia loss and fertilizer 15N recovery in no‐till winter wheat following BROADCAST UREA APPLICATIONS

Broadcast applications of urea during the overwinter period has been a common management practice for dryland winter wheat producers in Montana. Their long‐held belief was that ammonia (NH3) volatilization risks associated with surface application of urea loss could be mitigated by applying urea to cold soils during this time. Does research support this belief? Earn 0.5 CEUs in Nutrient Management by reading this article and taking the quiz at www.certifiedcropadviser.org/education/classroom/classes/495

Soybean Response to Broadcast Application of Boron, Chlorine, Manganese, and Zinc

Core Ideas Application of B, Cl, and Zn increase soybean tissue concentration of each respective nutrient. Addition of B, Cl, Mn, and Zn do not increase soybean grain yield and have a marginal impact on soybean grain quality. Soil tests for B, Cl, and Zn do not predict soybean grain yield response and no relationships exist between trifoliate B, Cl, Mn, and Zn concentration to grain yield or their respective soil tests. It is unlikely that micronutrients are needed to increase soybean grain yield. Efficient use of micronutrients can potentially increase soybean [Glycine max (L.) Merr.] grain yield and economic return. The objectives of this study were to determine the effect of broadcast application of micronutrients on soybean tissue nutrient concentration and grain yield and the relationships between soil and plant tissue tests. Three separate research trials were conducted at 35 sites from 2011 to 2014. Soybean response to Zn application was evaluated in Study 1; B, Mn, and Zn in Study 2; and B, Cl, Mn, and Zn in Study 3. Fertilizers were broadcast applied to the soil surface and incorporated prior to planting. Application of B, Cl, and Zn increased soybean trifoliate concentration of each respective nutrient but application of Mn did not. Addition of B, Cl, Mn, and Zn did not increase soybean grain yield and had a marginal impact on soybean grain quality. Application of 2.2 kg B ha−1 sometimes reduced soybean grain yield. Soil tests for B, Cl, and Zn did not predict soybean grain yield response and there were no relationships between trifoliate B, Cl, Mn, and Zn concentration to grain yield or their respective soil tests. Increased soybean grain yield did increase the removal of micronutrients, but it is unlikely that micronutrients are needed to increase soybean grain yield. Results from these studies conducted across Minnesota showed that broadcast application of B, Cl, Mn, and Zn do not increase soybean yield except for low Mn (<20 mg kg−1) where Mn application could increase soybean yield.

Dynamic priority scheduling of periodic queries in on-demand data dissemination systems

As an important wireless data broadcast technique, on-demand broadcast has been widely used for dynamic and large-scale data dissemination. An important class of emerging data broadcast applications requires monitoring multiple data items continuously in order to support data-driven decision making. Since wireless bandwidth is a precious shared medium, an important problem to solve is how to disseminate data to periodic queries, so that all the requests can be satisfied while the bandwidth consumption is minimized. In this paper, we first propose a new real-time scheduling algorithm called EDFS, which is a variant of the classic EDF [24] algorithm. Based on EDFS, we propose a novel on-line broadcast scheduling algorithm, called EDFS-BS. To our best knowledge, EDFS-BS is the first dynamic priority based broadcast scheduling algorithm that can be utilized to satisfy the timing constraints of periodic queries. We also propose a bandwidth utilization based schedulability test for EDFS-BS, which is used to ensure timing predictability of a periodic query set. Extensive experiments have been conducted to compare EDFS-BS versus existing solutions with comparable quality. The results show that EDFS-BS outperforms them considerably in terms of wireless bandwidth consumption and query service ratio.

First Report of Mating Disruption With an Aggregation Pheromone: A Case Study With Tetropium fuscum (Coleoptera: Cerambycidae).

Tetropium fuscum (F.), native to Europe and established in Nova Scotia, Canada, since at least 1990, is considered a low-to-moderate threat to spruce (Picea spp.) forests in North America and regulated as a quarantine pest by the Canadian Food Inspection Agency. We tested broadcast applications of the aggregation pheromone racemic (5E)-6,10-dimethyl-5,9-undecadien-2-ol (fuscumol), formulated at 10% concentration in Hercon Bio-Flakes (Hercon International, Emigsville, PA), for efficacy in disrupting T. fuscum mating and suppressing populations. Two applications of 2.5-2.75 kg Bio-Flakes (250-275 g a.i.) per ha per season significantly reduced trap catches and mating success (2009, 2010, 2012): about 30% of females trapped in treated plots had mated compared with 60% of females trapped in untreated plots. Similar reductions in mating success were observed in 2011 with one or two 4.5 kg/ha applications of Bio-Flakes. Mean densities of T. fuscum colonizing sentinel bait logs or girdled trees were 36% lower in pheromone-treated plots than in untreated plots, but the difference was not statistically significant. Lack of population suppression may have been because mated females immigrated into treated plots or because populations were so high that despite a 50% reduction in mating success, absolute numbers of mated females were sufficient to infest our bait logs or trees. This is the first demonstration of insect mating disruption via broadcast application of an aggregation pheromone. Pheromone-mediated mating disruption has potential to slow the spread of invasive cerambycids by targeting low-density outlier populations near or beyond the leading edge of an infestation.

Late‐Fall, Winter, and Spring Broadcast Applications of Urea to No‐Till Winter Wheat II. Fertilizer N recovery, Yield, and Protein as Affected by NBPT

Core Ideas Fertilizer 15N recovery of urea (with and without NBPT) was directly related to cumulative NH3 loss. Spring applied urea provided better recovery than late‐fall and winter applications. NBPT improved fertilizer 15N recovery, particularly for late‐fall and winter applications that were most susceptible to volatility. Surface application of urea to winter wheat (Triticum aestivum L.) during the late‐fall, winter, or spring is a common practice in the northern Great Plains (NGP). However, surface applications are susceptible to volatilization, and management strategies are needed to enhance fertilizer‐N recovery (FNR). This study was conducted to determine the effect of urea application timing (late‐fall, winter, spring) and N‐(n‐butyl) thiophosphoric triamide (NBPT) on FNR in grain (FNRG) and grain plus straw (FNRT), and grain yield and protein. Replicated small‐plot experiments were conducted in no‐till winter wheat fields over 3 yr in Montana, and FNR was quantified using 15N‐enriched labeled urea (5% atom). Fertilizer‐N recovery was greater (P < 0.05) for spring (FNRG 36.5%, FNRT 46.1%) than late‐fall (FNRG 24.9%, FNRT 31.7%) and winter (FNRG 26.8, FNRT 34.1%) applications. Addition of NBPT to urea improved FNR of all urea timings, but the response was greater for late‐fall and winter compared with spring applications. Fertilizer‐N recovery among the management strategies tested was directly related to cumulative NH3 emissions (r2 = 0.77, P < 0.0001) measured in a companion study, indicating that volatilization represented an important pathway for N loss. Grain yield was not sensitive to application timing or NBPT. However, grain protein increased 6 to 8 g kg–1 from spring applications or NBPT additions. This study found that management strategies to enhance urea FNR in the NGP should consider delaying applications until the spring or addition of NBPT for late‐fall and winter applications that are more susceptible to NH3 volatilization.

Late‐Fall, Winter and Spring Broadcast Applications of Urea to No‐Till Winter Wheat I. Ammonia Loss and Mitigation by NBPT

Core Ideas Urea volatility was greater following late‐fall and winter applications to cold soils compared with spring applications to warmer soils. NBPT reduced cumulative NH3 loss from urea by 66%. Urea applications in the late‐fall and winter resulted in prolonged periods of NH3 flux. Surface urea applications in the late‐fall, winter, or early‐spring are common in Montana, but N applied at these timings is susceptible to volatilization. This study was conducted to quantify and contrast ammonia (NH3) loss from urea and urea plus N‐(n‐butyl) thiophosphoric triamide (NBPT) following late‐fall, winter, and spring applications (100 kg N ha–1). Experiments were run over 3 yr in farmer‐cooperator fields (>60 ha) under no‐till winter wheat (Triticum aestivum L.)–chemical fallow management. Ammonia emissions were quantified by the integrated horizontal flux method with samplers placed on a mast in the center of circular plots (20‐m radius). Prolonged periods of modest NH3 flux (≤33 g N ha–1 h–1) were found following late‐fall (87–106 d) and winter (48–62 d) urea applications before flux fell to nominal levels (≤3 g N ha–1 h–1). In contrast, NH3 flux following spring urea was generally lower in intensity (≤7 g N ha–1 h–1) and shorter in duration (14–30 d). Cumulative NH3 loss (% applied N) from urea was greater (P < 0.05) for late‐fall (16.4%) and winter (11.4%) than for spring (2.0%) applications. The weather pattern of light (≤6 mm), scattered precipitation events from December throught March vs. larger precipitation events (≥12 mm) in April and May was an important factor which helped explained this response. Addition of NBPT (1 g kg–1) to urea reduced cumulative NH3 loss by 65.6%. Urea applications during the over‐winter period (December–March) should be avoided, in favor of spring applications to minimize NH3 loss.

Nitrogen doses on soybean growth and Asian rust progress in two cultivars

The main goal of this study was to analyze the range of effects of nitrogen doses on Asian soybean rust (Phakopsora pachyrhizi Sydow) progress over two soybean (Glycine max Merril) cultivars. Two experiments were carried out in greenhouse and in the field, during the 2011/12 and 2012/13 crop years. In the greenhouse, plants were grown in sand in 2011/12 and in a mix of sand and soil in 2012/2013, and supplied with five N doses by dripping fertigation. In the field, the crop was fertilized with six nitrogen doses with broadcast applications. The pathogen was inoculated in all experiments. It was assessed the Area Under Rust Progress Curve (AURPC), defoliation, dry matter, total concentration of N in leaves, number of grains per plant, thousand grain weight and yield. In the greenhouse experiment, nitrogen rates increased the plant growth and the disease progress during the first year. In 2011/12 field assay, a slight decrease of rust progress and a slight increase in yield from 160 to 242 kg ha-1 were recorded. However, under favorable environmental conditions for Asian soybean rust, the increases in grain yield obtained by using high N rates on both cultivars were minor than the damage caused by the disease.

Effect of inhibitors and fertigation strategies on GHG emissions, NO fluxes and yield in irrigated maize

Abating large losses of nitrogen (N) oxides while maintaining or enhancing crop yield is a major goal in irrigated maize (Zea mays L) cropping areas. During two consecutive campaigns, the new nitrification inhibitor 2-(3,4-dimethyl-1H-pyrazol-1-yl) succinic acid isomeric mixture (DMPSA) applied with calcium ammonium nitrate (CAN) and the same fertilizer applied by drip-fertigation without the inhibitor, were evaluated and compared with CAN broadcast to the surface and irrigated with sprinklers. Concurrently, urea-based treatments such as urea-fertigation and the broadcast application of urea combined with sprinkler irrigation, with or without the urease inhibitor N-butyl thiophosphorictriamide (NBPT), were also assessed. Nitrous oxide (N2O) and nitric oxide (NO) fluxes, grain and biomass yield and yield-scaled N2O emissions of the different treatments were compared. Additionally, methane (CH4) and carbon dioxide (CO2) fluxes were measured. On average, fertigation treatments led to a mitigation of N2O emissions with respect to sprinkler irrigation by 80% and 78% for CAN and urea, respectively. With regards to inhibitor-based strategies, the use of DMPSA and NBPT reduced N2O losses by 58% and 51%, respectively, considering the average of both maize cropping seasons. Since no differences in grain yield were observed between fertilized treatments, DMPSA and fertigation treatments gave the lowest values of yield-scaled N2O emissions, leading to reductions of 63%, 71% and 78% for CAN with DMPSA, urea-fertigation and CAN-fertigation, respectively, with respect to conventional management strategies (surface broadcast application and sprinkler irrigation). Low NO emissions during the first campaign masked differences between treatments, whereas during the second season, NO losses significantly decreased in the following order: conventional treatments > inhibitors > fertigation. Comparing conventional management practices, CAN significantly decreased emissions of N oxides compared with urea, but this effect was only observed in the second maize cropping season. The moisture distribution pattern in drip plots (dry and wet areas) caused a reduction of CH4 sink (only in one of the two seasons) and respiration fluxes, in comparison to sprinkler. This study shows that the use of the new nitrification inhibitor DMPSA and drip-fertigation should be promoted in irrigated maize agro-ecosystems, in order to mitigate emissions of N oxides without penalizing grain yield and leading to similar or enhanced biomass production.

Herbicide options for managing competitive vegetation during the establishment of Pinus radiata and Pseudotsuga menziesii var. menziesii in Southland, New Zealand

BackgroundControl of weeds is important for survival, growth and uniformity of planted conifers, such as Pinus radiata D.Don and Pseudotsuga mensiesii var. menziesii (Mirb.) Franco. Despite pressure to find environmentally benign herbicides for these species, little research has identified non-residual herbicides that are cost-effective and result in minimal growth loss compared to those used operationally. The objective of this study was to compare efficacy and cost of current operational practice to a range of alternative herbicide treatments for the establishment of these two species using data from two trials located at the same site.MethodsTreatments for each species were applied in both the first and second year following planting and included weed-free controls, operational practice using terbuthylazine and hexazinone (applied as both spot treatment and broadcast application) and a range of treatments consisting of combinations of clopyralid, triclopyr and haloxyfop (CTH), applied with or without oversowing with less competitive grasses and annual herbaceous species. Application of glyphosate during winter was included within the Pseudotsuga mensiesii trial as a first year treatment only and as a second year treatment following spot application of CTH in the first year.ResultsFor the Pinus radiata trial, broadcast application of CTH in spring of years 1 and 2 was most effective, with mean stand volume (m3 ha−1), at 2.5 years, exceeding the weed-free control and operational treatment by 8 and 11%, respectively, although these differences were not statistically significant at the 5% level. Use of the operational treatment as a spot in the first year, followed by broadcast application of CTH in the second year, was moderately effective when used with or without oversowing. For the Pseudotsuga mensiesii trial, the four most effective treatments were the operational treatment, broadcast application of CTH during year 1 (CTH-Dec), broadcast application of CTH during spring of years 1 and 2, and broadcast application of glyphosate during winter (winter glyphosate). Although not significantly different, at 2.5 years mean stand volumes in these treatments were on average 24, 29, 33 and 35% lower than the weed-free control, respectively. Both CTH-Dec and winter glyphosate were less expensive than the operational treatment.ConclusionsThese results highlight potential treatments to either replace terbuthylazine and hexazinone, or reduce their use during establishment weed control for Pinus radiata and Pseudotsuga menziesii, notably for sites dominated by Cytisus scoparius L. (Scotch broom).

Coupling Dairy Manure Storage with Injection to Improve Nitrogen Management: Whole‐Farm Simulation Using the Integrated Farm System Model

Core Ideas Manure storage and injection strategies were simulated using the Integrated Farming Systems Model. Strategies were verified using field data. We compared manure storage in environmental and economic model outputs. Introducing 6 mo of storage on a PA dairy farm decreased whole‐farm NUE without manure injection. Manure injection and 6 mo of storage gave the best combination of profit and environmental outcome. Application of livestock manure to farm soils represents a priority nutrient management concern in the Chesapeake Bay watershed. Historically, strong emphasis has been placed on adding manure storage to dairy operations, with the recognition that manure application methods can be improved. The Integrated Farm System Model was used to simulate manure management on a typical Pennsylvania dairy farm (100 milking cows, 80 ha). Converting the operation from daily haul to 6 mo of storage with broadcast application did not substantially change nitrogen (N) losses to the environment. However, switching to manure injection conserved ammonium N and improved manure N use efficiency by crops, even though it increased N leaching by 27% with 6‐mo storage and 13% with 12‐mo storage. Increasing manure storage from 6 to 12 mo with manure injection reduced nitrate N leaching by 38%, due to better timing of manure application to crop growth, but lowered annual net returns. Overall, manure injection and 6 mo of storage resulted in the best combination of profit and environmental outcome.

Hawkeye: Cloud Computing Based Automated Video Error Detection in Real-Time

With the rapid development of video surveillance and broadcast systems monitoring the video quality becomes an important aspect to assure a better quality of service. Error detection is an important technique to measure the quality of videos transmitted over the unreliable network. With the advent of HDTV previously subtle errors in videos are becoming more prominent. In this paper, we want to propose a next generation cloud-based video error detection system using image/video processing technology for making the detection process real-time. At first, we introduce an automatic video error detection method and then propose a cloud computing platform. Finally, we integrate error detection method with cloud computing platform named Hawkeye to achieve a real-time video error detection system which ensures contents integrity and minimizes testing time and efforts required to keep ahead of other conventional quality check system. Extensive experiments on prominent datasets and telecasted videos show that the proposed algorithm is very much efficient to detect errors for video broadcast and surveillance applications in terms of computation time and the detection of distorted frames.

Nitrous Oxide and Ammonia Emissions from Injected and Broadcast-Applied Dairy Slurry.

Trade-offs associated with surface application or injection of manure pose important environmental and agronomic concerns. Manure injection can conserve nitrogen (N) by decreasing ammonia (NH) volatilization. However, the injection band also creates conditions that potentially favor nitrous oxide (NO) production: an abundant organic substrate-promoting microbial activity, anaerobic conditions favoring denitrification, and large local concentrations of N. We assessed differences in NH volatilization and NO emissions with broadcast application versus shallow disk injection of dairy slurry during the 2011 to 2013 growing seasons on a well-drained silt loam that received average manure-N application rates of 180 kg N ha via injection or 200 kg N ha via broadcast. Ammonia emissions were measured using a photoacoustic gas analyzer and chambers, and NO emissions were measured using syringes to draw timed samples from vented chambers with analysis by gas chromatograph. Results point to a 92 to 98% (3.02-11.05 kg NH-N ha) reduction in NH volatilization (for the initial sampling) with injection compared with broadcasting manure but also reveal 84 to 152% (725.9-3187.8 g NO-N ha) greater cumulative NO emissions. Although losses of N via NO emission were at least three orders of magnitude less than NH volatilization, their potential role as a greenhouse gas is of concern. Despite the potential greenhouse gas trade-offs associated with shallow disk injection of manure, decreasing NH volatilization provides a substantial benefit, especially to farmers who are trying to conserve N and improve the N/P ratio of soil-applied manure.

Methyl Bromide Alternatives for Control of Root-knot Nematode (Meloidogyne spp.) in Tomato Production in Florida.

The following work was initiated to determine the scope of application methodology and fumigant combinations for increasing efficacy of 1,3-dichloropropene (1,3-D) and metam sodium for management of root-knot nematodes (Meloidogyne spp.) in Florida. A series of five experiments were set up during spring and fall seasons to evaluate the potential of different fumigants, alone or in combination, in polyethylene film tomato production. The most promising chemical alternatives to methyl bromide, in terms of root-knot nematode management, were the combinations 1,3-D-chloropicrin, chloropicrin-proprietary solvent ,and 1,3-D-metam sodium. Sprayed or injected metam sodium generally provided only short-term nematode management and by harvest nematode infection was not different from the nontreated control. Drip-applied metam sodium gave good nematode management under high nematode pressure, but needs further verification to establish (i) the importance of soil moisture and temperature on treatment efficacy and (ii) whether similar management can be obtained with fewer than three drip tubes. Broadcast applications of 1,3-D showed better efficacy as compared to applications on a preformed raised bed. Fumigation did not increase tomato yields in spring when root-knot nematode pressure was low, but during fall all chemical treatments increased yields three to five-fold, as root-knot nematode was a major yield-limiting factor.

Effect of Application Rate of Urea on the Growth, Bulb Yield and Quality of Onion (Allium Cepa L.) Grown under Semiarid Conditions of North Jordan

Field experiment was conducted to assess the effect urea fertilizer rates on growth and yield of onion (Allium cepa.var Giza 20) grown under semi-arid conditions of north Jordan, during 2011–2013. Transplants of uniform size were used. The treatments consisted four levels of urea(0, 200,400 and 600 kg ha -1) were applied as broadcast. The experimental design used was randomized complete block design. A significant increase in bulb weight per plant, number of leaves, plant height,neck diameter, leaves weight,bulb diameter,bulb lengthand plant weight with urea application at all rate was recorded and the highest bulb weight was registered for 600 kg ha -1. Agronomic urea efficiencyas well as vitamin c declined with increase in rates of urea application, while ash percentage increased with increase in rates of urea application. These results suggest that broadcast application of urea significantly influenced the growth, yield and vitamin c of onion.

Nitrogen dynamics following slurry injection in maize: crop development

Using pig slurry as starter fertilizer for maize (Zea mays L.), injected below the row prior to planting is a reasonable way to omit application of additional mineral fertilizer in areas with intensive animal farming. However, delayed early growth and a lack of knowledge on nutrient availability limit the interest of farmers. To extenuate farmers concerns a field trial was conducted in 2014 and 2015 to get detailed information on nitrogen (N) uptake, the subsequent influences on crop growth at different vegetative growth stages and final yield of silage maize. Besides an unfertilized control, two liquid manure injection treatments (without and with nitrification inhibitor [NI]) were compared to slurry broadcast application + mineral N and phosphorus (P) starter fertilizer at planting (MSF). In 2014, NI treatment yields increased (+16.5%) and N uptake increased (+9.6%) compared to broadcast treatment. In 2015, cold and dry conditions during early growth limited P plant availability and reduced crop growth in treatments without MSF. However, when a NI was added to the slurry prior to application, plants showed less P deficiency symptoms and better growth. At harvest no differences between the fertilized treatments were observed. In both years apparent N recovery was increased when manure was injected (48% without, and 56% with NI, respectively) compared to broadcast application of manure (43%) indicating that N losses were lower. However, further knowledge on soil N transformation and N loss pathways in systems with slurry injection is needed.

Nitrogen and Phosphorus Runoff Loss during Summer Season in Sandy Loam Red Pepper Field as Affected by Different Surface Management Practices in Korea

A field study was conducted to determine the runoff loss of N and P in small scale of red pepper field plots (10% slope), consisting of three different plots with black polyethylene vinyl mulching (mulching), ridge without mulching (ridge), and flat without ridge and mulching (flat). Composted manure and urea as a basal application were applied at rates of 20 MT ha-1 and 93 kg N ha-1, respectively. Urea at 189 kg N ha-1 and fused phosphate at 67 kg P2O5 ha-1 were additionally applied on June 25 with different fertilization methods, broadcast application in flat plot and hole injection in ridge and mulching plots. Plant uptake of N and P was positively correlated with their respective concentrations in surface soil: mulching > ridge > flat plots. The runoff loss by soil erosion was higher in flat plot than ridge and mulching plot with contour line. Nitrate loss by the runoff water had no significant differences among three surface management practices, but the higher average value in ridge and mulching plots than flat plot. Especially, the flat plot had no phosphate loss during summer season. This is probably due to low labile P content in surface soil of flat plot. In the summation of soil and water loss, flat plot was higher in N and P loss than ridge and mulching plot with contour line. Nevertheless, the nitrate and phosphate loss by runoff water could be more important for non-point source management because the water could meet the river easier than eroded soil because of re-deposition around slope land.The cumulative runoff amounts of soil/water (a,d), nitrogen (b,f), and phosphorus (c,g) by rainfall. Vertical bars indicate standard deviations of the means.

Nitrogen dynamics following slurry injection in maize: soil mineral nitrogen

In northwestern Germany slurry injection below maize (Zea mays L.) seeds is gaining increasing interest of farmers, because of the expected enhanced nitrogen (N) and phosphorus (P) use efficiencies compared to the usual fertilizing practice. The present study aims to compare the spatial and temporal soil mineral nitrogen (SMN) dynamics for these fertilizing strategies. Field trials with four treatments (unfertilized control, broadcast application + N P mineral starter fertilizer (+MSF), injection and injection + nitrification inhibitor (NI)) were conducted using pig slurry on sandy soil in 2014 and 2015. Soil samples were taken from three soil layers at 30 cm intervals down to 90 cm, and at three positions (below the maize row, 15 and 30 cm distance to the row) at several dates over the growing season. Soil monoliths (15 × 15 × 10 cm) were sampled around the injection zone, and for all other soil zones an auger was used. In 2014 due to heavy rainfall all fertilized N was displaced from the top soil layer of the broadcast treatment until 6-leaf stage, while N displacement was significantly smaller after slurry injection (about 20 kg SMN ha−1 more in top layer). The lateral movement of injected slurry N was negligible. In 2015 almost no displacement of fertilized N out of the top soil layer occurred independently of treatments, because of lower rainfall. The release of slurry N was delayed following broadcast application and large SMN concentrations were detected in the injection zones until 10-leaf stage. The addition of a NI resulted in significantly increased ammonium N concentrations in the injection zone throughout the early growth stages [+46 % (2014) and +12 % (2015) at 6-leaf stage]. Thus, N displacement was delayed in 2014 and in 2015 at 6-leaf stage increased SMN concentrations (+1/3 with NI) were found around the slurry band. Due to slurry injection, especially when combined with a nitrification inhibitor, the applied nitrogen is located in a soil zone with better spatial availability for plant roots compared to broadcast application and the risk of nitrate leaching is significantly reduced.

A Unified Metric for Correlated Diversity in Wireless Networks

Recent pioneer work has shown that packet receptions on adjacent links are correlated, which contradicts the long held assumption that wireless links are statistically independent. Since wireless link correlation affects a wide range of protocol designs, it is essential to quantify the impact generically. In particular, this paper focuses on a unified transmission cost metric for diversity-based routing schemes, including opportunistic routing, network coding, and hybrid routing. This paper covers both unicast and broadcast. Compared with the legacy metrics, our metric provides a direct and accurate estimation of the transmission cost in the presence of link correlation. The new metric helps a wide range of routing algorithms determine when they can benefit from reception diversity, and how to maximize the benefit, at negligible costs. We evaluate the metric on one 802.11 test bed and three 802.15.4 test beds running TelosB, MICAz, and GreenOrbs nodes. The experimental results show that our metric 1) reduces 92% and 94% of the estimation error of the transmission cost in unicast and broadcast and 2) outperforms the link independent metric in both unicast and broadcast applications.

Nutrient Runoff Losses from Liquid Dairy Manure Applied with Low‐Disturbance Methods

Manure applied to cropland is a source of phosphorus (P) and nitrogen (N) in surface runoff and can contribute to impairment of surface waters. Tillage immediately after application incorporates manure into the soil, which may reduce nutrient loss in runoff as well as N loss via NH volatilization. However, tillage also incorporates crop residue, which reduces surface cover and may increase erosion potential. We applied liquid dairy manure in a silage corn ( L.)-cereal rye ( L.) cover crop system in late October using methods designed to incorporate manure with minimal soil and residue disturbance. These include strip-till injection and tine aerator-band manure application, which were compared with standard broadcast application, either incorporated with a disk or left on the surface. Runoff was generated with a portable rainfall simulator (42 mm h for 30 min) three separate times: (i) 2 to 5 d after the October manure application, (ii) in early spring, and (iii) after tillage and planting. In the postmanure application runoff, the highest losses of total P and dissolved reactive P were from surface-applied manure. Dissolved P loss was reduced 98% by strip-till injection; this result was not statistically different from the no-manure control. Reductions from the aerator band method and disk incorporation were 53 and 80%, respectively. Total P losses followed a similar pattern, with 87% reduction from injected manure. Runoff losses of N had generally similar patterns to those of P. Losses of P and N were, in most cases, lower in the spring rain simulations with fewer significant treatment effects. Overall, results show that low-disturbance manure application methods can significantly reduce nutrient runoff losses compared with surface application while maintaining residue cover better than incorporation by tillage.

What motivates farmers to apply phosphorus at the “right” time? Survey evidence from the Western Lake Erie Basin

Abstract Phosphorus loadings from the Maumee River watershed have significantly compromised the Lake Erie ecosystem, as evidenced by the most severe harmful algal bloom in Lake Erie in 2015 and the shut-down of Toledo drinking water supply in 2014. Despite government payments for adoption of voluntary conservation practices, excess nutrient runoff from agricultural production remains a substantial challenge. The right timing of nutrient application is a critical best management practice (BMP). Using a unique survey of 2540 farmer respondents in the Maumee River watershed, this paper analyzes how socio-psychological, socio-demographic, and field-based spatial characteristics impact farmers' adoption of timing-related best practices for nutrient management, including delaying broadcast application before a storm event, avoiding winter application of nutrients, and avoiding fall application of nutrients. Results reveal three unique classes of farmers for each of the timing-related management decisions. While the significance of most farmer and field characteristics varies across the three BMP adoption decisions, perceived efficacy—the belief that the particular practice will actually reduce dissolved phosphorus runoff from farm fields—is positively correlated with a higher likelihood of adopting each of the BMPs across almost all classes of farmers. For example, results from the ordered logit model suggest that a 20% increase in perceived efficacy would result in the likelihood of actual adoption of delaying broadcast from 35% to 48%. An implication is that policies and outreach efforts aimed at increasing farmers' perceived efficacy of practices could lead to higher adoption levels, but the effectiveness may vary across different classes of farmers.