Receiving Poultry Litter Research Articles

Effectiveness of flue gas desulfurization gypsum in reducing phosphorus solubility in poultry litter when applied as an in-house amendment

Phosphorus (P) runoff from agricultural lands receiving poultry litter (PL) poses a major environmental challenge. Application of flue-gas-desulfurization (FGD)-gypsum produced from coal power plants in agricultural lands has shown promise to reduce P losses. However, no information is available about the effectiveness of FGD-gypsum addition in reducing P solubility when applied as an in-house amendment. Hence, the objectives of this study were to understand a) effectiveness of FGD-gypsum as a litter amendment in reducing P loss risk; and b) how FGD-gypsum amendment in PL alters the distribution of P forms. Broiler chickens were raised for five flocks in seven individual litter treatments replicated four times in a randomized complete block design. Based on the FGD-gypsum addition, the PL treatments were broadly classified as FGD-gypsum treated and untreated. Toxic metal concentrations were analyzed in FGD-gypsum as well as the treatments. Sequential water extractions were performed to understand P solubility. Litter P fractionation was performed to identify bioavailable P (Water-P), labile P (NaHCO3-P), aluminum/iron chemisorbed P (NaOH-P), and mineral occluded P (HCl-P). Results indicated significantly higher soluble P in all untreated than in all FGD-gypsum treated litters in the initial water extraction. The FGD-gypsum treated litters reduced soluble P by 58 to 67% in the 1st water extraction compared to untreated litters. Fractionation study revealed lower proportion of Water-P and higher proportion of NaHCO3-P and HCl-P in all FGD-gypsum treated than in untreated litters. This study suggests reuse of FGD-gypsum in broiler houses can help reduce P mobility without any toxic metals concerns.

Soil Organic Carbon and Nutrients Affected by Tree Species and Poultry Litter in a 17-Year Agroforestry Site

Tree species and fertilization sources may affect the soil organic carbon (SOC) and fertility in agroforestry (AF) systems in temperate regions, but this remains unexplored. This study assesses the longitudinal trends in the SOC and major nutrients in a 17-year AF site established on an Ultisol in Fayetteville, AR. We evaluated how management and fertilization (mineral vs. organic) affect the soil’s physical and chemical properties using the tree species: red oak (Quercus rubra L.) and pecan Carya illinoinensis (Wangenh.) K. Koch. Long-term applications of poultry litter increased the soil pH, whereas the Mg and S concentrations decreased compared to the baseline levels (1999). Poultry litter increased the soil P concentration in 53% compared to the baseline levels and reduced the soil C:N ratio. After 17 years, increased Ca, SOC, and N concentrations were observed in the soils under the pecan stands that received poultry litter. Positive correlations occurred between the SOC and N (r = 0.96) as well as the Ca (r = 0.71) and P (r = 0.61) at a soil depth of 0–15 cm. Our findings demonstrated that the changes in SOC and fertility in the AF soils vary according to tree species and fertilization, mostly due to distinctive leaf litter and nutrient inputs. Organic matter accumulation increased the SOC retention and nutrient availability in the temperate AF systems.

Impact of Cover Crop on Nutrient Losses in an Upland Soil

ABSTRACT Nutrient losses through leaching and surface runoff are the main problems in no-till upland soils in Mississippi. A two-year study was conducted in 2016 and 2017 on an Atwood silt loam soil to evaluate the impact of winter wheat (Triticum aestivum L.) cover crop (WCC) in no-till dryland cotton (Gossypium hirsutum L.) received poultry litter (PL) on nitrogen (N) and phosphorus (P) losses in leached and surface runoff water. Experimental design comprised a split-plot with a 2 × 2 treatment arrangement replicated 3 times. Treatments included WCC and winter fallow (WF) were assigned to the main plots, while PL at the rate of 6.7 and 0 Mg ha−1 was assigned to the subplots. Wheat was planted after harvesting cotton and leachates were collected from October to April using suction cup lysimeters. Surface runoff was collected from the edge of the plots. Nitrate-N concentrations in leachate samples were 45% and 21% less with WCC (9.9 and 17.2 mg L−1) than winter fallow (WF) (18.2 and 22 mg L−1) in the first and second year, respectively. Residual soil NO3-N concentration at the top 15 cm depth before planting cotton was 41% greater with WF than with WCC. In each year, runoff volume and water-soluble P (WP) concentrations were greater with WCC than with WF. It appears that the cover crop utilizes N during its growth period and slowly releases it for the subsequent crops as evidenced by greater cotton dry matter, lint yield, and cotton N uptakes mainly in the first year.

Effects of Grazing Management and Buffer Strips on Metal Runoff from Pastures Fertilized with Poultry Litter.

Metal runoff from fields fertilized with poultry litter may pose a threat to aquatic systems. Buffer strips located adjacent to fields may reduce nutrients and solids in runoff. However, scant information exists on the long-term effects of buffer strips combined with grazing management on metal runoff from pastures. The objective of this study was to assess the 12-yr impact of grazing management and buffer strips on metal runoff from pastures receiving poultry litter. The research was conducted using 15 watersheds (25 m wide and 57 m long) with five treatments: hayed (H), continuously grazed (CG), rotationally grazed (R), rotationally grazed with a buffer strip (RB), and rotationally grazed with a fenced riparian buffer strip (RBR). Poultry litter was applied annually in spring at 5.6 Mg ha. Runoff samples were collected after every rainfall event. Aluminum (Al) and iron (Fe) concentrations were strongly and positively correlated with total suspended solids, indicating soil erosion was the primary source. Soluble Al and Fe were not related to total Al and Fe. However, there was a strong positive correlation between soluble and total copper (Cu) concentrations. The majority of total Cu and zinc was in water-soluble form. The CG treatment had the highest metal concentrations and loads of all treatments. The RBR and H treatments resulted in lower concentrations of total Al, Cu, Fe, potassium, manganese, and total organic carbon in the runoff. Rotational grazing with a fenced riparian buffer and converting pastures to hayfields appear to be effective management systems for decreasing concentrations and loads of metals in surface runoff from pastures fertilized with poultry litter.

Short-term nitrogen dynamics in soil amended with poultry litter containing woodchip bedding

Concurrent N mineralization and immobilization in soils receiving poultry litter containing woodchip bedding may reduce synchrony between the short-term N supply and crop N demand. Therefore, we used soil chemical tests, ion exchange membranes, and wheat N uptake to assess N dynamics in a poultry-litter-amended soil. Air-dried soil was thoroughly mixed with five poultry litter rates (50, 100, 150, 200, or 250 mg total N kg−1) and preincubated for 7 d in a controlled environment chamber. After preincubating, soil was placed in 10-cm-diameter pots and planted with spring wheat (Triticum aestivum ‘Wilkin’), or left unplanted and monitored with anion and cation exchange membranes for 45 d. Soil nitrate (NO3-N) concentration increased with poultry litter application rate at the end of the preincubation period, but subsequent wheat N uptake did not, suggesting that little net N mineralization occurred during the 45 d of wheat growth. The membrane data indicated a shift from net N immobilization during the early part of the wheat growth period to net mineralization during the latter portion of the wheat growth period. We conclude that alternating N mineralization and immobilization in soils receiving poultry litter containing woodchip bedding limited the short-term N supply to wheat.

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The increase in broiler production in Brazil has increased the production of poultry litter. Thus, the management and adequate disposal of this waste is recommended. Agricultural use is a promising solution. This study evaluated the productivity of corn for silage with different fertilizations of poultry litter. The production of Dry Matter (DM), Crude Protein (CP), Ether Extract (EE), Mineral Matter (MM) and Organic Matter (OM), and microbial activity of the soil such as Microbial Biomass Carbon (MBC), Metabolic Quotient (qCO2) and Microbial Quotient (qMIC), were evaluated. There were treatments composed of a control that received mineral fertilization (33 Kg N, 80 Kg P2O5 and 80 Kg K2O) and treatments with poultry litter Rice Straw (RS) and Wood Shavings (WSH) (doses of 2.5; 5.0; 7.5 and 10.0 Mg ha-1). The treatments with poultry litter received, at sowing, 1/3 of the mineral fertilization. The evaluation of the production of corn for silage was carried out in the R4-R5 phase, and soils collected in the 0 to 10 cm layer in the post-poultry litter (A) and post-herbicide (B) periods. The microbial communities were influenced by anthropic activity in every treatment, with fall in MBC and the significant increase in the qCO2 in the control and the qMIC in the treatments that received poultry litter, demonstrating greater efficiency in mineralization of nutrients. As regards DM productivity, there was no difference in the treatments; however, treatments 7.5 RS and 10 WSH presented higher levels of protein and ether extract similar to the control treatment. This study concluded that the treatments with poultry litter favored the use of soil OM, which had less impact on microbial activity, and proposed that the substitution of 2/3 of the fertilization would not cause losses or decrease in the production or characteristics of the corn silage. Key words: Zea mays, organic fertilization, organic matter and poultry waste.

Nutrient cycling in an agroforestry alley cropping system receiving poultry litter or nitrogen fertilizer

Optimal utilization of animal manures as a plant nutrient source should also prevent adverse impacts on water quality. The objective of this study was to evaluate long-term poultry litter and N fertilizer application on nutrient cycling following establishment of an alley cropping system with eastern black walnut (Juglans nigra L.), pecan [Carya illinoensis (Wangenh.) K. Koch], and northern red oak (Quercus rubra L.) trees and orchardgrass (Dactylis glomerata L.). One half of a 4.25-ha site in northwestern Arkansas USA received broadcast applications of 3.9–6.7 Mg ha−1 fresh poultry litter and the other half 50–76 kg ha−1 N as NH4NO3 fertilizer each spring from 2001 to 2008. Macronutrient (N, P, K, Ca, Mg, and S) and micronutrient (Na, Fe, Mn, Zn, and Cu) concentrations in soil, forage, and tree leaf tissue were monitored along with NO3-N in soil water and groundwater. Poultry litter application resulted in significantly increased concentrations of each macronutrient except S with increases from 6.3 (N) to 121 % (P). Nitrogen fertilizer application resulted in decreased concentrations from 2.1 (N) to 60.9 % (S) for all macronutrients except Ca. Patterns of nutrient content in forage and tree leaf tissue did not generally follow patterns of soil nutrient concentrations suggesting nutrient sufficiency in most years and that climate and plant growth had a greater effect on nutrient uptake. Soil P with litter application increased 41.3 mg kg−1 over 7 years (from 34.1 to 75.4), which may necessitate a lower litter application rate to avoid excessive P runoff.

Factors affecting arsenic and copper runoff from fields fertilized with poultry litter.

Arsenic (As) and copper (Cu) runoff from fields fertilized with poultry litter has received increasing attention in recent years, although it is not known if heavy metal runoff from poultry litter poses a significant threat to the environment. The objective of this study was to determine the main factors affecting As and Cu concentrations in runoff water from pastures receiving poultry litter applications. Rainfall simulation studies were conducted to determine the effects of the following treatments on metal runoff: (i) aluminum sulfate (alum) additions, (ii) diet modification using phytase or high available phosphorus corn, (iii) fertilizer type, (iv) poultry litter application rate, and (v) time until the first runoff event occurs after poultry litter application. Results showed that alum additions to poultry litter significantly decreased As and Cu concentrations in runoff water. Copper concentrations were highest in runoff from poultry litter from birds fed phytase diets compared with other diets; however, this effect may have been a result of wet storage conditions rather than diet. Triple superphosphate applications resulted in the lowest heavy metal concentrations in runoff water among all fertilizer treatments, while normal poultry litter resulted in the highest concentrations. Arsenic and Cu concentrations increased in runoff water as poultry litter application rates increased and decreased with increasing time until the first runoff event. These data indicate that adding alum to poultry litter, a cost-effective best management practice, which also results in lower P runoff and ammonia emissions, may also be an effective tool in reducing metal runoff.

Impact of flue gas desulfurization gypsum application on water quality in a coastal plain soil.

There are growing concerns regarding the fate of nutrients, especially phosphorus (P), from land application of animal waste. One approach being studied to reduce runoff losses of P is to treat manure or the soil receiving manure with chemical amendments such as gypsum. This study used rainfall simulations to examine the impact of flue gas desulfurization (FGD) gypsum application on runoff nutrient losses on a Coastal Plains soil (Luverne sandy loam; fine, mixed, semiactive, thermic Typic Hapludults). Four rates of FGD gypsum (0, 2.2, 4.4, and 8.9 Mg ha) were applied to plots of Coastal Bermudagrass ( L.) that had received application of 13.4 Mg ha poultry litter. Plots with 8.9 Mg ha FGD gypsum but no poultry litter and plots with neither poultry litter nor FGD gypsum were also used. Rainfall simulation was used to generate water runoff for 60 min, and samples were analyzed for soluble reactive P (SRP) and soluble Al, B, Ca, Cu, Fe, K, Mg, Mn, Na, and Zn. Total concentration of Ca, Mg, K, Na, Fe, Mn, and Zn and concentration of heavy metals Ar, Hg, Al, Sb, Ba, Be, Cd, Cr, Co, Cu, Pb, Ni, Si, V, Se, Tl, and hexavalent chromium were also analyzed. Results indicated a maximum of 61% reduction in SRP concentration in runoff with the application of 8.9 Mg ha FGD gypsum. This translated to a 51% reduction in total SRP load during the 60-min runoff event. Concentrations of heavy metals in runoff were all found to be below detection limits. The results indicated that use of 4.4 Mg ha FGD gypsum on Coastal Plains pastures receiving poultry litter could be an effective method of reducing SRP losses to the environment.

Trace Metal Enrichment and Distribution in a Poultry Litter-amended Soil under different Tillage Practices

Macro and micro nutrients enrichment from poultry litter amendment, tillage, and crop rotation have been in- vestigated to determine their impacts on crop yield, soil and environmental sustainability. This study was conducted to evaluate the soil arsenic (As), copper (Cu), lead (Pb), nickel (Ni) and zinc (Zn) enrichment that could result from the long term effect of poultry litter amendments and tillage practices on selected soil properties at the Alabama Agricultural Ex- periment Station, Belle Mina, AL. Soil samples were collected in 2006 from plots established in 1996 that received yearly poultry litter applications with three tillage systems, conventional-till (CT), no-till (NT), and mulch-till (MT); and at three depths (0-10 cm, 10-20 cm, and 20-30 cm) that received poultry litter based on 100 kg total N ha -1 yearly. An untreated control was also included in the study. Soil pH values at the 0-10 cm were greater or equal to the lower depths. Copper and Zn concentrations were significantly higher for all tillage systems at the 0-10 cm depth compared to the 10-20 and 20- 30 cm depths and decreased with increasing depth. For example, at 0-10 cm depth Cu concentrations were 58, 66 and 65 and Zn were 13, 24 and 22 percent higher than the control for the CT, MT and NT tillage practices respectively. These re- sults demonstrated that Cu and Zn did accumulate in the surface soil after 10 annual applications of poultry litter but not at phytotoxic levels in contrast to As, Pb, and Ni regardless of the tillage practices.

17β-estradiol in runoff as affected by various poultry litter application strategies

Steroidal hormones, which are excreted by all mammalian species, have received increasing attention in recent years due to potential environmental implications. The objective of this study was to evaluate 17β-estradiol concentrations in runoff water from plots receiving poultry litter applications using various management strategies. Treatments included the effects of 1) aluminum sulfate (alum) application rates to poultry litter; 2) time until the first runoff event occurs after poultry litter application; 3) poultry litter application rate; 4) fertilizer type; and 5) litter from birds fed modified diets. Rainfall simulators were used to cause continuous runoff from fertilized plots. Runoff samples were collected and analyzed for 17β-estradiol concentrations. Results showed that increasing alum additions to poultry litter decreased 17β-estradiol concentrations in runoff water. A significant exponential decline in 17β-estradiol runoff was also observed with increasing time until the first runoff event after litter application. Concentrations of 17β-estradiol in runoff water increased with increasing litter application rate and remained above background concentrations after three runoff events at higher application rates. Management practices such as diet modification and selection of fertilizer type were also shown to affect 17β-estradiol concentrations in runoff water. Although results from these experiments typically represented a worst case scenario since runoff events generally occurred immediately after litter application, the contaminant loss from pastures fertilized with poultry litter can be expected to be much lower than continual estradiol loadings observed from waste water treatment plants. Management practices such as alum amendment and application timing can significantly reduce the risk of 17β-estradiol losses in the environment.

Inferring Mobility of Trace Elements Resulting From Long-term Poultry Litter Additions to Benchmark Alabama Soils

Poultry litter when applied to agriculture lands contains high trace element concentrations that may become toxic to plants and pose a risk to surface water and groundwater. We evaluated whole soil elemental concentrations throughout the soil profile using the US Environmental Protection Agency digestion method 3052 for Alabama benchmark soils that had received more than 20 years of poultry litter. Paired soils that had not received poultry litter were equivalently characterized. Pairwise comparison tests indicate that trace element concentrations were significantly greater (P < 0.05) in poultry litter–amended soils than those in nonamended soils. Cadmium, As, Cu, Ni, and Cr concentrations significantly increased with soil profile depth relative to those in nonamended soils. Chromium concentration significantly increased from 38.8 mg kg (0–15 cm) to 116 mg kg (75–90 cm) in Malbis soil. The downward migration of these metals and metalloids may pose a risk to shallow groundwater resources and, if the soil is eroded, may pose a risk to surface water resources.

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.

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.

Dissolved Organic Carbon and Estrogen Transport in Surface Runoff From Agricultural Land Receiving Poultry Litter1

Dutta, Sudarshan, Shreeram Inamdar, Jerry Tso, Diana S. Aga, and J. Tom Sims, 2012. Dissolved Organic Carbon and Estrogen Transport in Surface Runoff from Agricultural Land Receiving Poultry Litter. Journal of the American Water Resources Association (JAWRA) 48(3): 558‐569. DOI: 10.1111/j.1752‐1688.2011.00634.xAbstract: Dissolved organic carbon (DOC) provides a reactive substrate for the transport of organic contaminants with runoff. Very few studies have investigated the export of DOC from agricultural land, especially those receiving manure applications. We investigated exports of DOC in surface runoff from agricultural fields receiving various treatments of poultry litter (raw vs. pelletized). In addition, we also investigated how estrogens in runoff were associated with DOC. Different forms of estrogens studied were: estrone, 17β‐estradiol, estriol, and their conjugates. Experimental agricultural plots were 12 m × 5 m long and had reduced tillage and no‐till management practices. The aromatic content of DOC was characterized using specific ultraviolet absorbance (SUVA). Flow‐weighted concentrations of DOC and SUVA in surface runoff from plots with poultry litter were significantly (p ≤ 0.10) greater than the control (no litter) plots. Compared to pelletized poultry litter, reduced‐tillage plots with raw litter yielded higher DOC concentrations and SUVA values. No significant differences (p ≥ 0.10) in DOC and SUVA were observed between litter treatments for plots with no‐till. Total estrogen concentrations (including all forms) were positively and significantly (p ≤ 0.10) correlated with DOC. These results can help select and guide agricultural management practices that can reduce the exports of DOC and associated contaminant from agricultural land receiving manure applications.

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.

Long‐Term Tillage and Poultry Litter Impacts on Soybean and Corn Grain Yield

Reduced tillage, poultry litter applications, crop rotations, and winter cover cropping are management practices that could be used with conservation tillage systems to increase yields compared to conventional monoculture systems. This study evaluated cropping sequences of corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and corn–soybean rotations with wheat (Triticum aestivum L.) covers in conventional, strip, and no‐tillage (no‐till) systems, following poultry litter additions to wheat cover. The study was conducted from 1991 to 2001 on a Hartsells fine sandy loam (fine‐loamy, siliceous, subactive, thermic Typic Hapludults). Poultry litter (112 kg N ha−1) was applied to wheat each year in fall. Wheat not receiving poultry litter received equivalent inorganic N. Corn was fertilized with inorganic fertilizer in spring with 56 kg N ha−1 at planting followed by 168 kg N ha−1 3 wk after emergence; soybean received no fertilizer. Corn yields were influenced by tillage in 1991, 1992, 1993, 1994, 1996, 1997, 1998, and 2001 with conventional tillage producing greater yields, except in 1993 (strip tillage) and 2001 (no‐till). Poultry litter increased corn yield in 1991, 1997, and 1998. Crop rotations increased corn yield for all years, except 2001. Soybean yields were not impacted by differences in tillage. Crop rotations significantly impacted soybean yield in 1992, 1995, and 1998, with higher yields observed in 1992, and 1995, and lower yields in 1998. Poultry litter significantly increased soybean yield 8 of the 9 yr evaluated. This study suggests that poultry litter use for these crop rotations in conservation tillage systems could increase sustainable yield production.

An Environmental Threshold of Soil Test P and Degree of P Saturation of Brazilian Oxisols

AbstractTo develop P management guidelines for poultry litter application in Oxisols of Brazil, the relationship between water soluble P (WSP), soil test P (STP), and degree of P saturation (DPS) needs to be established. The study examined this relationship in Oxisols of Brazil receiving poultry litter. Soils were analyzed for Mehlich‐1 P (M1‐P), WSP, P fractions, P sorption index (PSI), and P saturation based on Mehlich‐1 extractable P, Al, Fe (DPSM1), and PSI (DPSPSI). Surface water bodies in the catchment area were examined for inorganic and total P. All the surface water bodies in the catchment area of the sampled plots were highly enriched in inorganic and organic P. Enrichment of soil P fractions following poultry litter application followed the order HCl‐bound &gt; NaOH‐bound &gt; NaHCO3‐bound fraction. M1‐P was correlated to labile (NaHCO3‐Pi), and stable P pools (NaOH‐P and HCl‐P) and reflected the cumulative P accumulation in these soils. P saturation indices increased with cumulative P addition and increasing M1‐P. WSP increased with increasing DPS and a change point was noticed at 23% DPSPSI (equivalent to DPSM1 of 16.5%) corresponding to M1‐P of 44.5 mg P kg−1, which could be regarded as threshold for P loss in these soils.

THE EFFECTS OF GROUNDCOVER MANAGEMENT AND NUTRIENT SOURCE DURING ORGANIC ORCHARD ESTABLISHMENT

Expansion of organic tree fruit production in the southern region of the USA has been hindered by lack of reliable, regionally appropriate, and scale-neutral technologies. In March 2006, an experimental organic apple orchard of 'Enterprise'/M26 was planted in a replicated trial to examine the effects of three organic fertilizer treatments (control, composted poultry litter and commercial pelletized fertilizer) and four groundcover treatments (shredded paper, wood chips, municipal compost and mow-blow), with the goal of developing organic management recommendations. The effects of nutrient and ground cover treatments on tree growth, canopy and root development, soil biological, chemical and physical characteristics, foliar nutrient content, and weed density were evaluated during the establishment period of the orchard as a precedent for cropping. This paper reports on the effects of these treatments on early tree growth, development, and physiology. Significant differences have been found among the organic production systems were observed after two seasons of growth. Trees grown with ground cover managed with compost or wood chips were larger than those using shredded paper or mow-blow. Both composted poultry litter and commercial fertilizer resulted in trees larger than trees which derived nutrition solely from the ground cover treatments without additional nutrients. In the third season, trees with compost or woodchip mulch had significantly more flowers, more harvested fruit, and higher fruit set than those grown with mow-blow or shredded paper. Trees that did not receive supplemental nutrition had significantly fewer flowers, fruit set, and harvested fruit, compared with those receiving poultry litter or a commercial fertilizer.

Rainfall Sequence Effects on Phosphorus Loss in Surface Runoff from Pastures that Received Poultry Litter Application

Land application of poultry litter to pasture elevates the concentration of phosphorus in surface runoff, and it is becoming an increasing problem in sensitive water bodies. The objectives of this study were to assess the effects of soil test phosphorus (STP), surface application of poultry litter, rainfall/runoff sequences, and time after litter application on dissolved reactive phosphorus (DRP) in surface runoff from pasture in a greenhouse experiment using rainfall simulation. Treatment factors were poultry litter at a rate of 0.0 and 6.7 Mg ha-1, low and high STP, and three rainfall/runoff sequences (RRS). The latter refers to runoff-producing rainfall events starting from day 1, day 4, and day 7 after litter application. The study also included a rainfall simulation study of pasture field plots to investigate the effects of poultry litter and time after application on DRP in surface runoff, which was used to corroborate the greenhouse study. In both studies, runoff samples were taken at the end of 30 min of continuous runoff. Treatment effects on DRP concentrations in surface runoff were analyzed using ANOVA procedures using an alpha = 0.05. For the greenhouse study, poultry litter application, RRS, and time after litter application were found to have a highly significant effect on DRP concentration in surface runoff. Poultry litter had a significant effect on DRP concentrations in surface runoff until 18 days after litter application compared to the controls. Between 18 and 32 days after litter application, the effect on DRP became insignificant for any level of STP or rainfall sequence. A rainfall event without runoff reduced DRP concentration in the first surface runoff events by more than 50%. For the field plot study, DRP decreased rapidly with time, thereby corroborating the greenhouse study. The effect of poultry litter on DRP became statistically insignificant sometime between 35 and 161 days after application.