Subsurface Band Research Articles

Influence of Microstructural Inhomogeneity on Fracture Behaviour in SSM-HPDC Al-Si-Cu-Fe Component with Low Si Content

In the current paper, a low-Si containing aluminium alloy (1.4-2.2% Si) was used to fabricate a complex shape telecom component using Semi-Solid High-Pressure Die Cast (SSM-HPDC), process. Microstructure and fracture characteristics were investigated. The cast material exhibited microstructural inhomogeneity, in particular macrosegregation in the form of liquid surface segregation bands in addition to sub-surface pore bands and gross centre porosity. Tensile specimen were taken from the cast components. Elongation and microstructural inhomogeneity were investigated and correlated. Fracture surfaces of the tensile specimen were examined under scanning electron microscope (SEM). The study showed that both near surface liquid segregation bands and subsurface porosity strongly affected the fracture behaviour. Dominant for loss of ductility were gross centre porosity. This centre porosity was found to be a combination of trapped gas and insufficient, irregular feeding patterns.

Effect of poultry litter application method on ammonia volatilization from a conservation tillage system

Ammonia (NH₃) volatilization from agricultural fields is important economically as a direct loss of the valuable crop nutrient nitrogen (N), but it can also be a significant environmental concern for soil, air, and water quality of nearby ecosystems. As poultry production has expanded in cropland areas of the southeastern United States, poultry litter has become a major source of crop nutrients for farmers using conservation tillage systems. However, the conventional application method of broadcasting poultry litter on the soil surface can allow as much as 60% of the applied litter N to volatilize as NH₃. To provide management options that can prevent NH₃ losses and help farmers use poultry litter nutrients more efficiently, a research team at USDA9s Agricultural Research Service developed a prototype tractor-drawn implement for subsurface application of dry poultry litter in perennial pasture and conservation tillage systems. When compared to surface broadcasting, previous research showed that subsurface application of poultry litter decreased odor problems, increased crop yields, prevented more than 90% of nutrient losses in runoff, and prevented NH₃ volatilization from perennial pasture systems. The current study was conducted to expand our knowledge regarding the effect of this litter application method on NH₃ volatilization from row-crop conservation tillage systems. For two consecutive summers, field plots with a uniform high-residue surface cover of chopped wheat straw received about 5,000 kg ha⁻¹ (4,500 lb ac⁻¹) of poultry litter applied by surface spreading with no incorporation, surface spreading followed by light disking, or subsurface banding using the prototype USDA ARS applicator. Small mobile wind tunnels monitored NH₃ volatilization for at least five days after each litter treatment. Results for both years showed that NH₃ losses were consistently affected by diurnal variations that were closely related to the vapor pressure deficit. Compared to conventional surface spreading of poultry litter, NH₃ volatilization decreased an average of 67% when the litter application was followed by light disking, and decreased an average of 88% when the litter was applied below the soil surface using the prototype applicator. These data show that subsurface injection of dry poultry litter can preserve adequate surface cover for conservation needs while constraining NH₃ losses to minimal levels, thus conserving N for row crops and reducing potential nitrogen losses to the environment.

Implement with Adjustable Band Spacing for Subsurface Band Application of Poultry Litter

<abstract><title><italic>Abstract. </italic></title> Poultry litter, which is a mixture of poultry manure and a bedding material, is typically land-applied using broadcast application. During rainfall events, nutrients from surface-applied litter may be transported in runoff water, into streams, rivers, lakes, and other water bodies. A four-band implement for subsurface band application of poultry litter and similar solid products in row crops and pastures was developed. A novel feature of the implement is its adjustable band spacing, from 25 to 102 cm (10 to 40 in.) in 2.5 cm (1 in.) increments. Prior to development of the four-band implement, a single-band implement was developed. Using the implements, subsurface band application of broiler litter to row crops and pastures greatly decreased nutrient losses and bacterial concentrations in runoff water compared to surface broadcast application. Compared to surface broadcast application, subsurface band application increased cotton yield, improved cotton fiber length, and improved the efficiency with which cotton plants made use of the litter-derived nitrogen.

Nutrient Loss in Leachate and Surface Runoff from Surface-Broadcast and Subsurface-Banded Broiler Litter

Subsurface band application of poultry litter has been shown to reduce the transport of nutrients from fields in surface runoff compared with conventional surface broadcast application. Little research has been conducted to determine the effects of surface broadcast application and subsurface banding of litter on nutrients in leachate. Therefore, a field experiment was conducted to determine the effects of subsurface band application and surface broadcast application of poultry litter on nutrient losses in leachate. Zero-tension pan and passive capillary fiberglass wick lysimeters were installed in situ 50 cm beneath the soil surface of an established tall fescue ( Schreb.) pasture on a sandy loam soil. The treatments were surface broadcast and subsurface-banded poultry litter at 5 Mg ha and an unfertilized control. Results of the rainfall simulations showed that the concentrations of PO-P and total phosphorus (TP) in leachate were reduced by 96 and 37%, respectively, in subsurface-banded litter treatment compared with the surface-applied litter treatment. There was no significant difference in PO-P concentration between control and subsurface-banded litter treatment in leachate. The trend in the loading of nutrients in leachate was similar to the trend in concentration. Concentration and loading of the nutrients (TP, PO-P, NH-N, and NO-N) in runoff from the subsurface-banded treatment were significantly less than for the surface-applied treatment and were similar to those from control plots. These results show that, compared with conventional surface broadcast application of litter, subsurface band application of litter can greatly reduce loss of P in surface runoff and leachate.

NH3 volatilization, soil concentration and soil pH following subsurface banding of urea at increasing rates

Rochette, P., Angers, D. A., Chantigny, M. H., Gasser, M.-O., MacDonald, J. D., Pelster, D. E. and Bertrand, N. 2013. NH 3 volatilization, soil [Formula: see text] concentration and soil pH following subsurface banding of urea at increasing rates. Can. J. Soil Sci. 93: 261–268. Subsurface banding of urea can result in large ammonia (NH3) emissions following a local increase in soil ammonium ([Formula: see text]) concentration and pH. We conducted a field experiment to determine how application rates of subsurface banded urea impact NH3 volatilization. Urea was banded at a 5 cm depth to a silty loam soil (pH=5.5) at rates of 0, 6.1, 9.2, 13.3 and 15.3 g N m−1. Ammonia volatilization (wind tunnels), and soil [Formula: see text] concentration and pH (0–10 cm) were monitored for 25 d following urea application. Volatilization losses increased exponentially with urea application rate to 11.6% of applied N for the highest urea rate, indicating that as more urea N was added to the soil a larger fraction was lost as NH3. Cumulative NH3-N emissions were closely related (R 2≥0.85) to maximum increases in soil [Formula: see text] concentration and pH, and their combined influence likely contributed to the nonlinearity of the volatilization response to urea application rate. However, the rapid increase in NH3 losses when soil pH rose above 7 suggests that soil pH was the main factor explaining the nonlinear response of NH3 volatilization. When compared with previous studies, our results suggest that the response of NH3 volatilization losses to urea application rate in acidic soils are controlled by similar factors whether urea is broadcasted at the soil surface or subsurface banded.

Method of Soil Sampling following Subsurface Banding of Solid Manures

Soil sampling guidelines do not exist for fields fertilized with solid manures applied in bands. The objective of this work was to describe the distribution of mineral nutrients and total C and propose a method of taking soil samples that represent the fertility level of a field following manure application in narrow bands below the soil surface. Systematic soil core samples were taken from no‐till cotton (Gossypium hirsutum L.) plots fertilized with poultry litter in subsurface bands spaced ≈1 m apart and analyzed for total C, total N, and extractable P, K, Mg, Cu, Mn, Fe, and Zn. The results showed that total C and most of the mineral nutrients were not evenly or randomly distributed in the space between and across the bands because of the manure placement in narrow bands, nutrient movement away from the band, and plant uptake. Concentrations of P, K, Mg, Zn, Cu, and B in the soil samples taken over the band were elevated by up to 50 fold compared to the positions away from the band. This distribution shows that taking random soil samples from fields fertilized with manures in bands is not appropriate and that some systematic sampling schemes must be used to more accurately represent the soil nutrient status. We describe a new sampling method that takes into account the band width and the spacing between consecutive bands. The method is based on a proportional mixing of soil cores taken at predetermined distances from the manure band including one core directly over the band.

Mineral Composition of Cottonseed is Affected by Fertilization Management Practices

Cottonseed and its products can be used as human food, animal feed, and industrial raw material. Chemical composition is one of the critical parameters to evaluate cottonseed’s quality and potential end use. Whereas there are reports on the improvement of cotton (Gossypium hirsutum L.) lint yield by poultry litter (PL) fertilization, there are no data about the impact of PL application on mineral composition of cottonseed. In this study, we collected seed samples in 2 yr from cotton fertilized with PL and chemical inorganic fertilizer (CIF) with or without winter wheat (Triticum aestivum L.) cover crop (CC) at the Mississippi Agricultural and Forest Experiment Station. Contents of 18 elements (Al, As, B, C, Ca, Cd, Cu, Fe, K, Mg, Mn, N, Na, Ni, P, Pb, S, and Zn) and ash in these cottonseed samples were determined by inductively coupled plasma‐based or dry combustion methods. Cover crop did not significantly impact the chemical composition of cottonseed. Compared to no fertilizer control, both CIF and PL altered the levels of Ca, Mg, Cu, Fe, Mg, Mn, P (possibly Na and K), and ash contents but not C, N, Zn, Ni, Cd, Pb, Al, S, B and As. The impact of subsurface band vs. broadcast application methods or fall vs. spring application timing on mineral composition was not obvious. Cottonseed K, Mg, and P contents were higher with PL fertilization but lower with CIF than those of the control cottonseed (no fertilizer). The data of the three elements were highly correlated (α &lt; 0.01), indicating the three elements were co‐accumulated in cottonseed.

Runoff Quality from No-Till Cotton Fertilized with Broiler Litter in Subsurface Bands

Surface broadcast of broiler litter to no-till row crops exposes the litter and its nutrients to risks of loss in runoff water and volatilization and may limit the potential benefit of litter to the crops. Subsurface banding of litter could alleviate these risks. A field study was conducted in 2008 and 2009 on an upland Falkner silt loam soil to determine the effect of broiler litter placement on runoff nutrient losses from no-till cotton ( L.). Treatments included surface broadcast broiler litter applied manually, subsurface-banded litter applied by tractor-drawn equipment, and no broiler litter, all in combination with or without winter wheat ( L.) cover crop residue. Broiler litter rate was 5.6 Mg ha. The experimental design was a randomized complete block with a split-plot arrangement of treatments replicated three times. In 2008, simulated rainfall was used to generate runoff 27 d after litter application. Subsurface-banded litter reduced runoff total C, N, P, NH, NO, Cu, Zn and water-soluble P (WP) concentrations by 72, 64, 51, 49, 70, 36, 65, and 77%, respectively, compared with surface broadcast. The reductions were greater in 2009 where runoff occurred 1 d after litter application. Bacterial runoff was decreased by one log with subsurface-banded litter compared to surface broadcast. Except for C, NH, N, and WP, the presence of winter cover crop residue did not affect the load or runoff nutrient concentrations in either year. The results indicate that subsurface banding litter to no-till cotton substantially reduces nutrient and bacterial losses in runoff compared with surface broadcasting.

THz excitation spectra of AIIIBV semiconductors

The dependence of terahertz (THz) radiation on the excitation wavelength of femtosecond pulses (from 640 to 2600 nm) was investigated. Four different materials, InAs, InSb, InN and GaAs, were analyzed. The generated THz amplitude increases linearly with the photon energy due to the reduced absorption length and the increased quasi-ballistic transit distance. When the electron excess energy reaches the position of the subsidiary conduction band valleys, the intervalley scattering sets in and the THz amplitude drops. Thus, this method allows us to determine intervalley separation of various semiconductors. THz generation due to subsurface band bending in GaAs was observed as well.

Impact of Tillage and Fertilizer Application Method on Gas Emissions in a Corn Cropping System

Tillage and fertilization practices used in row crop production are thought to alter greenhouse gas emissions from soil. This study was conducted to determine the impact of fertilizer sources, land management practices, and fertilizer placement methods on greenhouse gas (CO2, CH4, and N2O) emissions. A new prototype implement developed for applying poultry litter in subsurface bands in the soil was used in this study. The field site was located at the Sand Mountain Research and Extension Center in the Appalachian Plateau region of northeast Alabama, USA, on a Hartsells fine sandy loam (fine-loamy, siliceous, subactive, thermic Typic Hapludults). Measurements of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions followed GRACEnet (greenhouse gas reduction through agricultural carbon enhancement network) protocols to assess the effects of different tillage (conventional vs. no-tillage) and fertilizer placement (subsurface banding vs. surface application) practices in a corn (Zea mays L.) cropping system. Fertilizer sources were urea-ammonium nitrate (UAN), ammonium nitrate (AN) and poultry litter (M) applied at a rate of 170 kg ha−1 of available N. Banding of fertilizer resulted in the greatest concentration of gaseous loss (CO2 and N2O) compared to surface applications of fertilizer. Fertilizer banding increased CO2 and N2O loss on various sampling days throughout the season with poultry litter banding emitting more gas than UAN banding. Conventional tillage practices also resulted in a higher concentration of CO2 and N2O loss when evaluating tillage by sampling day. Throughout the course of this study, CH4 flux was not affected by tillage, fertilizer source, or fertilizer placement method. These results suggest that poultry litter use and banding practices have the potential to increase greenhouse gas emissions.

Assessment of Soil Phosphorus and Potassium following Real Time Kinematic‐Guided Broadcast and Deep‐Band Placement in Strip‐Till and No‐Till

Fertilizer placement may cause non‐uniform nutrient distribution in the soil, making it difficult to determine whole‐field fertility by traditional sampling strategies. Our objectives were to determine P and K distribution after repeated applications in no‐till and strip‐till soils and to develop improved sampling procedures to estimate soil P and K levels on a corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] rotation with crops planted at 76‐cm row spacing. Three trials near Pesotum, IL, received blends of 0–0, 22–42, 33–62, 44–83, 55–104, 66–125, and 77–145 kg P–K ha−1 in fall 2007 and 2009 before corn planting. Applications were broadcast‐applied in no‐till (NTBC) and strip‐till (STBC) and deep‐banded in strip‐till (STDB) 15 cm below the surface in the crop row (IR) using real‐time kinematic (RTK) satellite navigation. Every year soil P and K was measured at 10‐cm increments to a 30‐cm depth at 0, 19, 38, and 57 cm from the IR. Subsurface banding reduced P and K levels in the surface and increased them at the point of application, or deeper with the highest rate, while broadcast applications increased surface levels. Soil‐surface K levels were greater at IR likely because of K leaching from senescing standing crops. Soil‐test results indicated no need to adjust fertilizer rate based on tillage or fertilizer placement. A sampling ratio of 1:3 IR to between the crop rows (BR) seemed adequate to estimate soil fertility across a wide range of P‐ and K‐fertilizer rates and soil test levels where the location of the fertilizer band or planting row is maintained constant.

Subsurface Application of Dry Poultry Litter: Impacts on Common Bermudagrass and Other No-Till Crops

Poultry manure provides a rich organic nutrient source to fertilize crops and help neutralize soil acidity. However, the usual practice of broadcasting litter on the surface of pastures and other no-till systems can degrade water quality by allowing nutrients to be transported from fields in surface runoff, while much of the ammonium-N volatilizes and escapes into the atmosphere. In a previous study, we used a subsurface banding technique to move litter from the soil surface into the root zone with minimal disturbance of the grass, thatch, and soil structure; and found that nutrient losses decreased substantially. Because subsurface banding increased retention of nutrients and water in the soil, we conducted follow-up research to compare crop yield and quality from this litter application method to those from the conventional surface broadcasting method. The objectives were to determine effects of subsurface application on perennial forage yield, quality, and temporal yield distribution during the growing season. Field plots were located on silt loam soil (8-10% slopes) with well-established bermudagrass (Cynodon dactylon L. Pers.). Poultry litter was applied (6.7 Mg ha-1, dry weight) by one of two methods: surface broadcast manually or subsurface banded using a tractor-drawn prototype implement. Each treatment was replicated three times. There were also three control plots that received no litter. Results showed that subsurface application generally increased forage quality and yield, especially in the latter part of the growing season when forage production from surface-applied litter began to decline. Under the growing conditions in this study, subsurface application increased mean forage yield by as much as 40%.

Broiler Litter Type and Placement Effects on Corn Growth, Nitrogen Utilization, and Residual Soil Nitrate‐Nitrogen in a No‐Till Field

Broiler litter is generally land applied by surface broadcasting, a practice that exposes litter nutrients to volatilization and surface runoff losses potentially contaminate environment. Placing litter in narrow bands below the soil surface may eliminate such losses but this practice has not been evaluated. Field experiments were conducted in 2008 and 2009 on a private farm in Caledonia, MS on a Caledonia silt loam (fine‐loamy, siliceous, semiactive, thermic Typic Paleudalf) to determine the effects of broiler litter types and placements on corn (Zea mays L.) grain yield, N utilization, postharvest stalk nitrate (NO3–N) and residual soil NO3–N. Six treatments were used in a randomized complete block with four replications. Treatments were an unfertilized control, inorganic N fertilizer at the rate of 180 kg ha−1, subsurface and surface broadcast of nonpelletized and pelletized litter at the rate of 11.2 Mg ha−1. No differences in grain yield, total N uptake, and apparent N use efficiency were obtained between pelletized and nonpelletized litter when subsurface banded. However, for surface broadcast the values were greater for pelletized than nonpelletized litter. Nonpelletized litter applied in a subsurface band had 16% greater grain yield, 9% higher harvest index, 19% more N used and 56% greater in apparent N use efficiency compared with surface broadcast. Subsurface banding of nonpelletized broiler litter is an effective manure management strategy for corn production under no‐till systems.

Surface Transport of Nutrients from Surface-Broadcast and Subsurface-Banded Broiler Litter

Nutrient buildup, mainly phosphorus (P), and loss from fields fertilized with poultry (broiler) litter contribute to eutrophication of surface waters. In the U.S., broiler litter is typically surface-applied, but recently, to reduce surface transport of P and other nutrients, subsurface-banding of broiler litter has been promoted as a new manure application method. The objective of this study was to evaluate differences in nutrient transport between subsurface-banded and surface-applied broiler litter in a tall fescue pasture. Treatments were surface-applied and subsurface-banded broiler litter at a rate of 5.0 Mg ha-1, and no application of litter (control). Results showed that runoff concentrations and loadings of total P (TP), ortho-P (PO4-P), nitrate-nitrogen (NO3-N), and ammonium-N (NH4-N) were reduced by 83%, 88%, 74%, and 80%, respectively, for the subsurface-banded litter as compared to the surface-applied litter. Concentrations and loadings of all nutrients in surface runoff from the subsurface-banded treatment were similar to those from the control. This study showed that subsurface banding of broiler litter can substantially reduce nutrient losses in surface runoff. However, since less than 10% of the simulated rainfall contributed to surface runoff (more than 90% rainfall infiltrated), subsurface transport of nutrients from surface-applied and subsurface-banded litter needs to be studied in field research.

Subsurface Application of Poultry Litter and Its Influence on Nutrient Losses in Runoff Water from Permanent Pastures

Environmental pressure to reduce nutrient losses from agricultural fields has increased in recent years. To abate this nutrient loss to the environment, better management practices and new technologies need to be developed. Thus, research was conducted to evaluate if subsurface banding poultry litter (PL) would reduce nitrogen (N) and phosphorus (P) loss in surface water runoff using a four-row prototype implement. Rainfall simulations were conducted to create a 40-min runoff event in an established bermudagrass (Cynodon dactylon L.) pasture on soil types common to the Coastal Plain and Piedmont regions. The Coastal Plain soil type was a Marvyn loamy sand (fine-loamy, kaolinitic, thermic Typic Kanhapludults) and the Piedmont soil type was a Hard Labor loamy sand (fine, kaolinitic, thermic Oxyaquic Kanhapludults). Treatments consisted of surface- and subsurface-applied PL at a rate of 9 Mg ha(-1), surface broadcast-applied commercial fertilizer (CF; urea and triple superphosphate blend) at the equivalent N (330 kg N ha(-1)) and P (315 kg N ha(-1)) content of PL, and a nonfertilized control. The greatest loss for inorganic N, total N, dissolved reactive P (DRP), and total P occurred with the surface broadcast treatments, with CF contributing to the greatest loss. Nutrient losses from the subsurface banded treatment reduced N and P in surface water runoff to levels of the control. Subsurface banding of PL reduced concentrations of inorganic N 91%, total N 90%, DRP 86%, and total P 86% in runoff water compared with surface broadcasted PL. These results show that subsurface band-applied PL can greatly reduce the impact of N and P loss to the environment compared with conventional surface-applied PL and CF practices.

Tillage and Fertilizer Management Effects on Soil-Atmospheric Exchanges of Methane and Nitrous Oxide in a Corn Production System

Land application of poultry litter (PL) presents an opportunity to improve soil productivity and disposal of poultry waste. We investigated methane (CH4) and nitrous oxide (N2O) emissions from agricultural soil receiving PL and ammonium nitrate (AN) fertilizers using surface (SA), soil incorporation (SI), and subsurface band (BA) application methods in conventional (CT) and no-tillage (NT) systems on a Decatur silt loam soil in North Alabama. Plots under CT and NT were sinks of CH4in spring, summer, and fall. In winter, the plots had net emissions of 3.32 and 4.24 g CH4ha-1day-1in CT and NT systems, respectively. Plots which received AN were net emitters of CH4and N2O, whereas plots which received PL were net sinks of CH4. Plots which received PL using SA or SI methods were net emitters of N2O, whereas under PL using BA application, the plots were net sinks of N2O. Our study indicates that using subsurface band application of PL was the most promising environmentally sustainable poultry waste application method for reducing CH4and N2O emissions from agricultural soil in NT and CT corn production systems on the Decatur soil in north Alabama.

Technical Note: Calculation of Effective Gas Flux from Soil Following Band Application of Manure or Fertilizer

Greenhouse gases are emitted following application of manure and nitrogen-containing fertilizers to soil. Manure and fertilizers are often applied in subsurface bands in the soil, or in bands on the soil surface. This article presents a method that has been developed for calculating the effective gas flux for a multiple-band area to which manure or fertilizer has been applied in bands. The method has been developed for circular and rectangular flux chambers. In analyzing the method, a combination of CO2 gas fluxes from a field experiment that gave a relatively low whole-plot effective flux and a combination that gave a relatively high whole-plot effective flux were used. For the lower-end flux situation, when the dimension of the flux chamber in the direction perpendicular to the band is considerably less than the band spacing, if the flux in a chamber that is centered on a band is assumed to be the whole-plot effective flux, then this assumption would overestimate the actual whole-plot effective flux by a considerable amount. The error of this type of assumption is reduced for the higher-end flux situation, regardless of flux chamber dimensions, and is reduced when the lower-end flux situation occurs and the dimension of the flux chamber in the direction perpendicular to the band is intermediate to nearly as large as the band spacing. The method in useful in calculating effective gas fluxes for whole plots to which manure or fertilizer has been band-applied.

Delamination wear on two retrieved polyethylene inserts after gamma sterilization in nitrogen

Two self-aligning mobile bearing knee replacements (SAL-1) with gamma-in-nitrogen sterilized polyethylene inserts were revised due to instability after 6.3 years and after 14.2 years in vivo in two patients. The predominant damage features were burnishing, cracking, and delamination and were observed on the proximal bearing surface of the retrieved polyethylene inserts. This suggested an association with sub-surface fatigue, perhaps initiated by in vivo oxidative degradation which was confirmed by developing a sub-surface white band in one insert. The damage features observed on the distal bearing surface of the polyethylene inserts suggested both an adhesive wear mechanism and an abrasive wear mechanism. The titanium-nitrite coated, titanium-alloy tibial tray was severely worn in one case and possibly contributed to third-body abrasive wear at the distal surface interface. We suggest to carefully follow-up patients who received this type of mobile bearing knee system.

Water-quality effects of a mechanized subsurface-banding technique for applying poultry litter to perennial grassland

Poultry litter is known to be an excellent organic fertilizer, but the common practice of spreading litter on the surface of pastures has raised serious water-quality concerns and may limit potential benefits of litter applications. Because surface-applied litter is completely exposed to the atmosphere, runoff can transport nutrients into nearby streams and lakes, and much of the ammonium nitrogen volatilizes before it can enter the soil. Our previous research showed that a manual knifing technique to apply dry litter under a perennial pasture surface effectively prevented about 90% of nutrient loss with runoff from surface-applied litter, and tended to increase forage yield. However, this technique (known as subsurface banding) cannot become a practical management option for producers until it is mechanized. To begin that process, we tested an experimental single-shank, tractor-drawn implement designed to apply poultry litter in subsurface bands. Our objective was to compare this mechanized subsurface-banding method against conventional surface application to determine effects on nutrient loss with runoff from a perennial grassland treated with dry poultry litter. Early in the growing season, broiler litter was applied (6.7 dry-weight Mg ha −1) to each plot (except three control plots) using one of two application methods: surface broadcast manually or subsurface banded using the tractor-drawn implement. Simulated rainfall (5 cm h −1) generated 20 min of runoff from each plot for volume and analytical measurements. Results showed that subsurface-banded litter increased forage yield while decreasing nutrient (e.g. N and P) loss in runoff by at least 90% compared to surface-broadcast litter.

Influence of Poultry Litter Application Methods on the Longevity of Nutrient and E. coli in Runoff from Tall Fescue Pasture

Significant quantities of the broiler chicken (Gallus gallus domesticus) litter produced in the USA are being applied to pasture lands. The traditional surface- broadcast application of animal manure onto permanent pasture, however, may lead to high concentration of nutrients and pathogenic microorganisms near the soil surface that could be transported off site by runoff water. Subsurface banding of poultry litter has the potential to reduce nutrient and pathogen losses through runoff. However, this has not been thoroughly investigated. In this study, we used rainfall simulations to examine the effect of broiler litter application methods on the longevity of nutrient and Escherichia coli losses in runoff by successive runoff events. Runoff plots were constructed on Hartsells fine sandy loam (Typic Hapludults) soil with permanent Kentucky 31 tall fescue (Festuca arundinacea) pasture in Crossville, AL. Treatments included two methods of litter application (surface broadcast and subsurface banding), commercial fertilizer, and control (no litter or fertilizer applied). To evaluate the longevity of nutrient losses, simulated rainfall (110 mm h−1) was applied to each plot on days 1, 7, and 14 following litter and fertilizer applications. Total P (TP), inorganic N, and E. coli concentrations were all significantly greater in runoff from broadcast litter application than the subsurface litter banding treatments. The TP losses from broadcast litter applications averaged 6.5 times those from subsurface litter applications. About 81% of the runoff TP concentration was in the form of dissolved reactive phosphorus for both litter application methods. The average losses of NO3–N and total suspended solids from subsurface litter banding plots were 358 g ha−1 and 68 kg ha−1 compared to 462 and 60 kg ha−1 for the broadcast method, respectively. This study shows that subsurface banding of broiler litter into perennial grassland can substantially reduce nutrient and pathogen losses in runoff compared to the traditional surface-broadcast practice.