Poultry Litter Application Research Articles

The effect of poultry manure application rate and AlCl3 treatment on bacterial fecal indicators in runoff

Increasing costs associated with inorganic fertilizer have led to widespread use of broiler litter. Proper land application, typically limiting nutrient loss, is essential to protect surface water. This study was designed to evaluate litter-borne microbial runoff (heterotrophic plate count bacteria, staphylococci, Escherichia coli, enterococci, and Clostridium perfringens) while applying typical nutrient-control methods. Field studies were conducted in which plots with high and low litter rates, inorganic fertilizer, AlCl(3)-treated litter, and controls were rained on five times using a rain generator. Overall, microbial runoff from poultry litter applied plots was consistently greater (2-5 log(10) plot(-1)) than controls. No appreciable effect on microbial runoff was noted from variable litter application rate or AlCl(3) treatments, though rain event, not time, significantly affected runoff load. C. perfringens and staphylococci runoff were consistently associated with poultry litter application, during early rain events, while other indicators were unreliable. Large microbial runoff pulses were observed, ranging from 10(2) to 10(10) CFU plot(-1); however, only a small fraction of litter-borne microbes were recoverable in runoff. This study indicated that microbial runoff from litter-applied plots can be substantial, and that methods intended to reduce nutrient losses do not necessarily reduce microbial runoff.

Soil Carbon Dioxide Fluxes in Conventional and Conservation Tillage Corn Production Systems Receiving Poultry Litter and Inorganic Fertilizer

Soil management practices can alter the natural balance at the soil-plant-atmosphere ecosystem interface, which can significantly affect the environment. This study compared CO2 fluxes in conventional tillage (CT) and no-tillage (NT) corn (Zea mays L.) production systems receiving poultry litter (PL) and ammonium nitrate (AN) fertilizers on a Decatur silt loam soil in the Tennessee Valley region of North Alabama from Spring 2008 to Fall 2009. Soil CO2 flux in CT plots (9.5 kg CO2 ha−1 day−1) was significantly greater than that in NT plots (4.9 kg CO2 ha−1 day−1 in summer. Soil CO2 fluxes were lowest in fall where CT plots had a mean soil CO2 emission of 0.8 kg CO2 ha−1 day−1, while plots under NT and grass fallow system were sinks of CO2 with fluxes −0.6 and −1.0 kg CO2 ha−1 day−1, respectively. Mean soil CO2 flux averaged over seasons in NT plots was 36% lower than that in CT plots. Grass fallow plots were net sinks of CO2 with a mean CO2 flux of −0.4 kg CO2 ha−1 day−1. Our study showed that application of PL or AN fertilizer in NT systems can significantly reduce soil CO2 emissions compared to CT systems in corn production.

Implementation of BMP Strategies for Adaptation to Climate Change and Land Use Change in a Pasture-Dominated Watershed

Implementing a suite of best management practices (BMPs) can reduce non-point source (NPS) pollutants from various land use activities. Watershed models are generally used to evaluate the effectiveness of BMP performance in improving water quality as the basis for watershed management recommendations. This study evaluates 171 management practice combinations that incorporate nutrient management, vegetated filter strips (VFS) and grazing management for their performances in improving water quality in a pasture-dominated watershed with dynamic land use changes during 1992–2007 by using the Soil and Water Assessment Tool (SWAT). These selected BMPs were further examined with future climate conditions (2010–2069) downscaled from three general circulation models (GCMs) for understanding how climate change may impact BMP performance. Simulation results indicate that total nitrogen (TN) and total phosphorus (TP) losses increase with increasing litter application rates. Alum-treated litter applications resulted in greater TN losses, and fewer TP losses than the losses from untreated poultry litter applications. For the same litter application rates, sediment and TP losses are greater for summer applications than fall and spring applications, while TN losses are greater for fall applications. Overgrazing management resulted in the greatest sediment and phosphorus losses, and VFS is the most influential management practice in reducing pollutant losses. Simulations also indicate that climate change impacts TSS losses the most, resulting in a larger magnitude of TSS losses. However, the performance of selected BMPs in reducing TN and TP losses was more stable in future climate change conditions than in the BMP performance in the historical climate condition. We recommend that selection of BMPs to reduce TSS losses should be a priority concern when multiple uses of BMPs that benefit nutrient reductions are considered in a watershed. Therefore, the BMP combination of spring litter application, optimum grazing management and filter strip with a VFS ratio of 42 could be a promising alternative for use in mitigating future climate change.

Phosphorus saturation of a tropical soil and related P leaching caused by poultry litter addition

Phosphorus deficiency is well known as a major agronomic constraint in the highly weathered Oxisols of Brazil and reasonable economic returns are not possible without application of high rates of phosphorus. Poultry litter, which is enriched in P, is increasingly being used in organic management of cultivated lands. Due to the great P fixing capacity of these soils, any limit to the soil sink of P is not recognized. The study was undertaken to evaluate the risk of P loss due to increase in phosphorus sorption saturation (PSS) from land application of poultry litter and to establish a relationship between PSS and water soluble phosphorus. No till corn-fallow rotation was followed for three years with annual application of 0, 5, 10, 25, 50 and 100Mgha−1 of poultry litter in a highly weathered clayey dystrophic red-yellow Argisol of Brazil. The effect of poultry litter application on soil was evaluated and Mehlich-3 P (PM-3) concentrations increased 3–134 times over control after three years of poultry litter application. Poultry litter application increased pH and decreased the concentration of exchangeable Al; whereas concentrations of K+, Na+, Zn2+, Mg2+ and Ca2+ increased substantially over control. Increase in soil pH and total organic carbon due to poultry litter application reduced the P sorption capacity of soils and P sorption. The PSS increased considerably at higher rates of poultry litter application (>10Mgha−1) and strongly increased the amount of desorbable P. Total water extractable P was mostly accounted for by reactive P forms and increased with poultry litter rates. In a plot of dissolved reactive P (DRP) against PSS, a change point was observed at 22.7% PSS corresponding to a dissolved reactive P (DRP) concentration of 0.92mgkg−1 soil after which a sharp increase in DRP was observed. P concentration >0.1mgL−1 was observed in soil solution at 60cm soil depth with increasing rates of poultry litter application, thus providing evidence of P leaching. In the absence of an environmental soil test criteria for P, the break point PSS of 22.7% could be used to practically monitor whether soils have reached a level of P loading that constitutes an environmental risk of P losses from soil to surface and ground waters.

Watershed‐level Comparison of Predictability and Sensitivity of Two Phosphorus Models

Buildup of phosphorus (P) in agricultural soils and transport of P to nearby surface waters due to excessive, long-term application of poultry litter is an environmental concern in many poultry-producing states. Watershed models are often used to quantify soil and water quality impacts of poultry litter applications. However, depending on how P transport is simulated in watershed models, the anticipated impact could be quite different. The objective of this study was to determine the predictability and sensitivity of the Soil and Water Assessment Tool (SWAT) P model and a newly developed, state-of-the-art manure P model called SurPhos in a poultry litter-applied pasture watershed. A small, predominantly agricultural watershed in Randolph County, Alabama was used for this study. The SWAT model, calibrated for surface runoff and total stream flows (Nash-Sutcliffe coefficient of 0.70 for both), was used to provide runoff inputs to the SurPhos model. Total dissolved P (TDP) exports simulated by the SWAT P and SurPhos models from the hay hydrological response units of the watershed were compared for different poultry litter application rates and different initial soil Solution P levels. Both models showed sensitivity to poultry litter application rates, with SWAT simulating linear and SurPhos simulating nonlinear increases in TDP exports with increase in poultry litter application rates. SWAT showed greater sensitivity to initial soil Solution P levels, which can lead to overestimation of TDP exports, especially at low poultry litter application rates. As opposed to the SurPhos model simulations and contrary to recent studies, SWAT simulated excessive accumulation of Solution P in the top 10 mm of soil. Because SurPhos appears to simulate P transport and build-up processes from manure-applied areas more accurately, this study suggests that SWAT be replaced by SurPhos to more accurately determine watershed-level effectiveness of P management measures.

Atributos de solo sob pastejo rotacionado em função da aplicação de cama de peru

Adições de dejetos de aviário podem promover melhorias nos atributos biológicos, físicos e químicos do solo. O presente estudo objetivou avaliar os efeitos de doses sequenciais de cama de peru nos atributos de solo sob pastejo rotacionado com Brachiaria decumbens L., em Portelândia (GO). O delineamento utilizado foi em blocos casualizados, em esquema de parcela subdividida, com quatro repetições. Os tratamentos alocados nas parcelas foram doses de cama de peru [ausência de adubação; 8,7 Mg ha-1 (2008); 16,5 Mg ha-1 (2008 + 2009); 30,9 Mg ha-1 (2008 + 2009 + 2010)], sendo que as duas maiores doses resultaram do acúmulo das aplicações de dejeto. Como subparcelas, foram consideradas as profundidades amostradas (0-5 cm, 5-10 cm e 10-20 cm). Aplicações sequenciais de cama de peru promoveram melhorias na fertilidade do solo, com aumento de pH, P, K, saturação por bases e estoque de carbono orgânico, nitrogênio total e particulado e diminuição na saturação por alumínio. A aplicação de menores doses de cama de peru estimulou a atividade microbiana do solo, promovendo a mineralização da fração particulada da matéria orgânica, porém, não houve efeito na agregação do solo.

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.

Using Cultural Practices and Cultivar Resistance to Manage Phytophthora Crown Rot on Summer Squash

The effects of bed height, mulches, composted poultry litter, and cultivars on Phytophthora crown rot, caused by Phytophthora capsici Leonian, of summer squash (Cucurbita pepo L.) were evaluated in the absence of fungicide applications. The experimental design was a split-split-split plot arrangement of a randomized complete block. Bed height (flat or raised) was the main plot treatment. Mulches (bare soil, wheat straw, or plastic) were subplot treatments. Composted poultry litter applications (0 or 4.5 t·ha−1) were sub-subplot treatments. Squash cultivars (Cougar or Payroll) were sub-sub-subplot treatments. Incidence of plant death (%) was assessed from 0 to 35 days post-inoculation (dpi) with P. capsici. Plant death 35 dpi and area under the disease progress curve (AUDPC)differed significantly (P < 0.0001) between the cultivars Cougar and Payroll. Mean plant death 35 dpi was 87% for ‘Payroll’ and 99% for ‘Cougar’. The bed height × cultivar interaction was also significant (P = 0.0018) in the analyses of variance for plant death and AUDPC. Plant death at 35 dpi and AUDPC for ‘Payroll’ were greater in flat beds than raised beds. Disease was unaffected by the main effects of bed height, mulch type, or application of poultry litter. Thirty-two summer squash cultivars and 10 germplasm accessions were also evaluated for resistance to Phytophthora crown rot in a separate greenhouse trial. Crown rot severity was rated on a 1 (no symptoms) to 5 (plant death) scale at 18 dpi. Crown rot severity differed significantly (P < 0.0001) among cultivars and germplasm accessions. Crown rot severity averaged 4.3 on commercial cultivars and 2.2 on germplasm accessions. Crown rot was least severe on the commercial cultivar Spineless Beauty (mean rating = 2.9). No disease developed on four accessions of Cucurbita moschata previously reported to be crown rot-resistant.

Soil Biochemical Changes Induced by Poultry Litter Application and Conservation Tillage under Cotton Production Systems

Problems arising from conventional tillage (CT) systems (such as soil erosion, decrease of organic matter, environmental damage etc.) have led many farmers to the adoption of no-till (NT) systems that are more effective in improving soil physical, chemical and microbial properties. Results from this study clearly indicated that NT, mulch tillage (MT), and winter rye cover cropping systems increased the activity of phosphatase, β-glucosidase and arylsulfatase at a 0–10 cm soil depth but decreased the activity of these enzymes at 10–20 cm. The increase in enzyme activity was a good indicator of intensive soil microbial activity in different soil management practices. Poultry litter (PL) application under NT, MT, and rye cropping system could be considered as effective management practices due to the improvement in carbon (C) content and the biochemical quality at the soil surface. The activities of the studied enzymes were highly correlated with soil total nitrogen (STN) soil organic carbon (SOC) at the 0–10 cm soil depth, except for acid phosphatase where no correlation was observed. This study revealed that agricultural practices such as tillage, PL, and cover crop cropping system have a noticeable positive effect on soil biochemical activities under cotton production.

Pecan Tree Productivity, Fruit Quality, and Nutrient Element Status using Clover and Poultry Litter as Alternative Nitrogen Fertilizer Sources

The recent increase in the cost of synthetic fertilizer dramatically reduces the profit margin for pecan [Carya illinoinensis (Wangenh.) K. Koch] producers. The objective of this study was to investigate the effects of clover and poultry litter on the orchard soil, horticultural, and nut quality parameters of pecan in the southeastern United States. The following treatments were evaluated; 1) crimson clover (Trifolium incarnatum L.); 2) poultry litter; 3) crimson clover + poultry litter; 4) ammonium nitrate (NH4NO3); and 5) untreated control. Application of poultry litter with or without clover often led to higher soil phosphorous (P) and potassium (K). Poultry litter application with and without clover led to higher leaf P in the final year of study. The recurring low pecan leaf K in the presence of clover without additional K application suggests that K nutrition may be especially important in orchards where clover is used. Clover and/or clover + litter occasionally led to enhanced pecan leaf concentrations of iron (Fe), copper (Cu), and zinc (Zn). Over the course of the study, yields were more consistent from year to year in the clover, litter, and clover + litter treatments, as indicated by the low alternate bearing intensity (I) from 2008 to 2011. Leaf elemental tissue analysis, pecan yield, and quality indicate that poultry litter and clover provide adequate nitrogen (N) nutrition for pecan production.

Release of arsenic and other trace elements from poultry litter: Insights from a field experiment on the Delmarva Peninsula, Delaware

A poultry litter application was conducted to examine field scale release and transport of trace elements from poultry litter into the subsurface. Field monitoring before and after litter application demonstrated increases in major ion, nutrient, and trace element concentrations in soil water after application, but concentrations of trace elements were all below regulatory standards. Using laboratory stepwise extractions of litter, calculated leaching rates of trace elements are fastest for As, followed by Cu and Zn. Comparison of the projected (from laboratory extractions) to actual (measured in the field) trace element concentrations in litter show that laboratory-derived rates generally over-predict leaching, but the long-term projections of Cu and Zn concentrations remaining in litter are within 20% of the field measurement. Arsenic leaching from litter was under-predicted by the laboratory leaching model by over 100%, suggesting that other processes (perhaps biological) occurring in the field allowed for additional As to be leached/removed. Mass balance coupled with conservative tracer calculations reveal that the vadose sediment was the main sink for the trace elements, with lesser uptake of Cu and Zn (not As) by orchard grass. Overall, results of this study showed that the fate and transport of trace elements from poultry litter are controlled by their leaching rate from litter, adsorption, uptake in vegetation and dilution. An additional process affecting As is biotransformation.

Effects of the Establishment of a Forested Riparian Buffer and Grazing on Soil Characteristics

Poultry-litter applications to pastures can result in relatively high soil phosphorus (P) levels, which in turn can contaminate runoff and degrade surface water quality. New management protocols for temperate grasslands are needed to reduce the risk of P transport to surface water. The effects of three land-use treatments on soil characteristics related to P runoff were investigated using small watersheds with 8% slope near Booneville, Arkansas, U.S. The land use treatments were (1) haying of bermudagrass overseeded with winter annual forage (ryegrass or rye), (2) rotationally grazed, and (3) rotationally grazed with 12-m-wide tree buffer on the downhill portion of the plot. Plots and trees were established in 2003. Annual spring application of poultry litter (5.6 Mg ha−1) to the hayed or grazed portions of the plots was started in 2004. Grazing treatments were imposed shortly thereafter. By the summer of 2008 (4 years of treatments), soil concentrations of Bray 1–extractable P and soluble reactive P had increased significantly from approximately 40 and 4 mg P kg−1 soil, respectively, to more than 200 and 30 mg P kg−1 soil, respectively, in the areas of the plots receiving poultry litter. Soil bulk density in the portions of the plots being grazed had increased significantly also. The soil collected from the forested riparian buffer in 2008 had similar soil bulk densities and Bray 1–extractable P concentrations as the plots did in 2003 before treatments were imposed.

Eutrophication and poultry industry: Issues, challenges and opportunities

Eutrophication is the process of excessive growth of algae and cynobacteria due to over enrichment of the surface waters with mineral nutrients. Eutrophication restricts water use for fisheries, recreation, industry and drinking. Phosphorus (P) is the limiting mineral for the eutropication process. Experience from America, Europe and Australia clearly shows that improper land application of poultry litter is among the main contributors of eutrophication process. Poultry utilizes dietary phosphorus rather inefficiently, due mainly to high level of phytate in their diets and, low intrinsic phytase activity both in poultry and plant materials. Phytates increase the excretion of N and a range of other cations and, thus increases the eutrophic potential of poultry litter. Poultry industry of Sri Lanka expanded dramatically during the last few decades and it has been predicted that the growth will continue. Meanwhile, use of poultry litter as an organic fertilizer is becoming popular, particularly in up country cropping systems. The risk of getting water bodies eutrophicated due to the present trend of indiscriminate land application of poultry litter in up country cropping systems is tremendous. Estimated minimum annual P output from local poultry industry is around 751.8 metric tonnes. Decreasing the P level in faeces through dietary manipulations is probably the most cost-effective and practical approach to reduce the P losses to the environment. In poultry ration formulation, the requirement of P is expressed as the non-phytate P requirement. No upper limits have been set for the total P level in the diet. This has given the liberty to the feed industry to use poorly digestible plant P sources in the diets. From environmental point of view, it is important to set maximum total P levels for poultry diets. Supplementation of poultry diets with microbial phytases can reduce the faecal P levels by about 30% and also faecal N and other cation levels. Regulatory mechanisms should be imposed to make the use of phytase compulsory, at least when the total dietary P levels exceed a particular limit. A range of chemical and physical means are also available to increase the P utilization in poultry. Both farmers and the feed industry should be encouraged to adopt those strategies. A maize variety with reducedphytate level has been successfully genetically engineered. Such genetically modified rice varieties are very much needed because the excretion of P is greatly increased when poultry diets contain rice bran. The dietary P levels commonly used in industry exceed the most recent NRC recommendations by about 15%. Many recent researches have shown that the dietary P levels could further be reduced without the performance being affected. The poultry feed industry should respond to these new findings rapidly and reduce the P levels in poultry diets. The dietary P requirement gradually declines as birds grown and mature. Theoretically, it is possible to prepare a series of diets containing decreasing P levels, and the feeding of such a series of diets as birds grow can reduce the P excretion. This paper concludes that the excretion of P from poultry industry could substantially be reduced through dietary manipulations and, timely intervention of policy makers, farmers and researchers is of paramount importance for the sustainability of inland water bodies

Recycling of nutrients with application of organic waste in degraded pasture

The utilization of organic wastes represents an alternative to recover degraded pasture. The experiment aimed to assess the changes caused by the provision of different organic waste (poultry litter, turkey litter and pig manure) in a medium-textured Oxisol in Brazilian Savanna under degraded pasture. It was applied different doses of waste compared to the use of mineral fertilizers and organic mineral and evaluated the effect on soil parameters (pH, organic matter, phosphorus and potassium) and leaf of Brachiariadecumbens (crude protein, phosphorus and dry mass production). It was observed that application of organic waste did not increase the level of soil organic matter and pH in the surface layer, and the application of turkey litter caused acidification at depths of 0.20-0.40 m and 0.40-0.60 m. There was an increase in P and K in the soil with the application of poultry litter and swine manure. All organic wastes increased the productivity of dry matter and crude protein and phosphorus. The recycling of nutrients via the application of organic waste allows efficiency of most parameters similar to those observed with the use of mineral sources, contributing to improving the nutritional status of soil-plantsystem.

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%.

Concentrations of Free and Conjugated Estrogens at Different Landscape Positions in an Agricultural Watershed Receiving Poultry Litter

Animal hormones can enter the aquatic environment along with runoff as a result of manure or litter application on agricultural landscapes. Our understanding of the transport of these hormones and their concentrations at various points along the watershed drainage is however limited. We investigated the transport of naturally produced poultry hormones in an agricultural watershed located on coastal plain soils of Delaware receiving land application of raw poultry manure. The objective of this study was to determine the concentrations of free and conjugated forms of estrogens in agricultural runoff at selected landscape positions in the agricultural watershed. Estrogen concentrations were determined for surface water, soil water, and runoff sediment. Estrogen forms that were analyzed were: Estrone (E1), Estradiol (E2β and E2α), Estriol (E3), and their sulfate and glucuronide conjugates. Poultry litter application occurred at a rate of 9 Mg ha−1 in early spring (April 2010). Sampling was performed for surface runoff, subsurface drainage, and sediment for nine storm events extending over 187 days before and after manure application (March–October 2010). Runoff was collected from the field edge, upland and lowland riparian positions and from the stream. Samples were analyzed by for liquid chromatography with tandem mass spectrometry (LC-MS/MS). Concentrations of estrogens were low (<20 ng l−1) for most of the samples and decreased from the field edge into the riparian zone. Estrogens were not detected in soil water and runoff sediments. Overall, this study suggests that manure application practices at our sites in Delaware such as incorporation of litter into the soil likely reduced the concentrations of estrogens in runoff and reduced the threat posed to aquatic ecosystems.

Poultry Manure Application Time Impact on Corn Grain Production in a Crider Silt Loam

Adopting proper management practices for poultry litter (PL) is critical to increase N efficiency, maximize yield, and reduce negative environmental impacts. This study investigated the effects of application time (fall and spring) of two PL rates (9.0 and 18.0 Mg ha) and commercial N-P-K fertilizer blend (224 kg N ha, 84 kg P ha, 145.6 kg K ha) on selected soil properties and corn (Zea mays L.) grain yield in Central Kentucky. Application time response was measured by grain yield, whole plant nutrient concentrations and uptake, and soil nutrients availabilities. Application time of the PL and commercial fertilizer did not influence grain yield or plant nutrient concentrations and uptake. Grain yield was increased by the two PL rates, and no difference was found among the PL and commercial fertilizer. Whole plant uptake and concentrations of N, P, and K increased when PL plant available N-P-K increased. Soil inorganic N was 17% (18 kg ha) greater from spring than fall applications of the high PL rate when sampled midseason. Application time did not influence inorganic N at the low PL rate. Greater soil available K resulted from fall than spring applications of the PL, but Mehlich 3 available P was not influenced by PL application time. Results indicate that fall applications of PL have equal potential as spring applications without compromising plant available nutrients and yield. In addition, the low PL rate was adequate in N, P, and K to meet the soil’s requirement for optimum yield, without significant nutrient accumulation and loss.

Variação nos atributos do solo em sistemas de manejo com adição de cama de frango

A cama de frango constitui-se em adubo orgânico com boas características agronômicas, podendo ser bom condicionador das propriedades físicas do solo. Assim, o objetivo deste trabalho foi verificar alterações nas propriedades do solo em sistemas de plantio direto com adição de cama de frango. O estudo foi feito em três camadas (0-10, 10-20 e 20-30 cm) e três repetições, em Latossolo Vermelho-Amarelo distrófico submetido a plantio direto contínuo nos últimos anos, com rotação principalmente de soja, milho, algodão e milheto. Os tratamentos foram: sistema com adubação mineral (S2), com adição de cama de frango crua (S3), com adição de cama de frango compostada (S4) e uma área não manejada de Cerrado nativo (S1). Os sistemas de manejo induziram em ordem crescente - S4, S2, S3 - à degradação dos atributos do solo em relação à vegetação nativa (S1), e isso foi quantificado pelos menores valores de carbono total, diâmetro e estabilidade de agregados, macroporosidade e condutividade hidráulica saturada e pelos maiores valores de densidade e resistência do solo à penetração e microporosidade. A cama de frango crua revelou-se mais vantajosa na disponibilidade de nitrogênio total e menos eficiente em garantir a qualidade física do solo. A cama de frango compostada proporcionou atributos mais semelhantes às condições naturais.

Assessing the Market for Poultry Litter in Georgia: Are Subsidies Needed to Protect Water Quality?

Concerns about nutrient loads into our waters have focused attention on poultry litter applications. Like many states with a large poultry industry, Georgia recently designed a subsidy program to facilitate the transportation of poultry litter out of vulnerable watersheds. This paper uses a transportation model to examine the necessity of a poultry litter subsidy to achieve water protection goals in Georgia. We also demonstrate the relationship between diesel and synthetic fertilizer prices and the value of poultry litter. Results suggest that a well-functioning market would be able to remove excess litter from vulnerable watersheds in the absence of a subsidy.

Soil microbial biomass nitrogen and β-glucosaminidase activity response to surface compaction and poultry-litter application in a claypan soil

In agroecosystems, compaction-induced changes in soil physical properties may significantly affect soil microbial activity, especially N-related processes. The objective of this study was to determine the effect of soil compaction on soil microbiological properties related to N in a claypan soil amended with poultry litter (i.e., Turkey ( Meleagris gallopavo) excrement mixed with pine shavings as bedding) and cropped to corn ( Zea mays L.). In a laboratory incubation, a silt loam soil was compacted to four bulk density levels (1.2, 1.4, 1.6 and 1.8 mg m −3) amended with and without poultry litter and incubated at 25 °C for 28 d. In a field experiment conducted in 2001 and 2002, a Mexico silt loam claypan soil was amended with litter (0 and 19 mg ha −1), left uncompacted or uniformly compacted and planted to corn or left fallow. In the incubation study, soil compaction reduced microbial biomass N (MBN) and soluble N (Sol N), but increased microbial C:N ratio and soil β-glucosaminidase activity. Added litter increased Sol N and soil β-glucosaminidase activity in the laboratory. Under controlled soil water content and temperature, all soil microbiological properties had a linear relationship with soil bulk density ( r 2 = 0.63**–0.90***). In the field, the compaction effect on all the measured soil microbial properties was less pronounced. The field observation also showed that litter-amended soil had higher MBN, Sol N and soil β-glucosaminidase activity compared to unamended soil in both compaction treatments, regardless of fallow and cropped plots. Under field conditions, MBN and microbial C:N ratio significantly correlated with soil water content ( r = 0.49*** and −0.32***, respectively), while soil β-glucosaminidase activity was correlated with total soil organic C ( r = 0.39***). The results showed that N-related soil microbiological properties were sensitive to changes induced by soil compaction, while beneficial effects of litter addition may mitigate some compaction effects on these soil properties.