Poultry litter is a mixture of excreta, bedding material, waste feed, and some soil that is removed from poultry houses and applied to soil as fertilizer. Because litter is commonly stockpiled outdoors before land application, losses of inorganic N may occur through denitrification and NH3 volatilization. This work was conducted to evaluate the effect of litter water content on denitrification and NH3 volatilization during storage. Litter samples from two broiler houses in northern Georgia were incubated (25°C) at four water contents for 13 d. Water contents used were 230 g H2O kg−1 in Litter A, 160 g H2O kg−1 in Litter B, and 800, 1200, and 2400 g H2O kg−1 in both litters. These water contents were equivalent to 8, 26, 40, and 79% water‐holding capacity (WHC) in Litter A and to 7, 33, 49, and 99% WHC in Litter B, respectively. Denitrification was evaluated by measuring N2O emission from samples incubated with 10 kPa C2H2, with and without additional NO−3 (15 mg Ng−1). Ammonia volatilization was evaluated by measuring NH3 evolved from samples incubated without C2H2. Denitrification was significant at the highest water content and increased with the addition of NO−3. Measured denitrification losses varied between 41 and 79% of the initial NO−3, although final NO−3 levels suggested that denitrification losses were larger (92–100%) and that part of the N2O produced remained entrapped in the litter. Ammonia volatilization losses ranged from 32 to 139% of the initial NH+4 and were increased by increasing water content. These results suggest that poultry litter should be stored under dry conditions to reduce N losses.

Passing poultry litter through a fine sieve (<0.83 mm) generates a fine fraction that is higher in N concentration than the whole litter and cheaper to transport per unit of N. This fine fraction can be pelletized to facilitate handling, but changing the physical characteristics of the litter may change the amount of N loss or the rate at which N mineralizes. The objective of this work was to evaluate the effect of physical characteristics of the fine poultry litter fraction (pelletized or fine particles) on net N and C mineralization, NH3 volatilization, and denitrification resulting from surface applications of the fine fraction to Cecil loamy sand (clayey, kaolinitic, thermic Typic Kanhapludult) and Dothan loamy sand (fine‐loamy, siliceous, thermic Plinthic Kandiudulf) soils. The soils were adjusted to 52% water‐filled porosity, treated with either pelletized or fine‐particle poultry litter at 30.7 g N m−2, and incubated at 25 °C for 35 d. Humidified air was circulated over each sample (15 chamber volumes min−1) and the NH3 evolved was trapped in 0.025 M H2SO4. Inorganic N contents and rates of denitrification and respiration were measured at 1, 3, 7, 14, 21, and 35 d after application. The physical characteristics of the litter did not affect total amounts of net N mineralized and NH3 volatilized in 35 d. However, total denitrification losses were significantly higher for pelletized (6.2% of the applied N in Dothan and 7.9% in Cecil) than for fine‐particle litter (0.2% in Dothan and 0.8% in Cecil). Thus, surface application of pelletized litter may result in increased denitrification losses compared with fine‐particle litter.

While several studies have shown that the addition of animal manures to soil can increase N20 and CO 2 emissions, limited information is available on the effect that manure physical characteristics can have on these emissions. This study compared N20 and CO2 emissions from poultry litter incorporated as pellets (5.5 mm OD, 7 mm long) or fine particles (<0.83 mm) into Cecil soil samples. The soil-litter mixture was packed in acrylic plastic cylinders and adjusted to 55 or 90 % water-filled porosity (WFP). The cylinders were placed inside jars that were sealed and placed in an incubator at 25°C for 35 d, with periodic air samplings conducted for N20 and CO2 analyses. At 55 % WFP, cumulative emission of CO2 was similar for both litter types, but cumulative emission of N20 was slightly higher for pelletized (6.8 % of applied N) than for fine-particle litter (5.5 %). In contrast, at 90 % WFP, cumulative emission of N20 was larger for fine-particle litter (3.4 % of applied N) than for pelletized litter (1.5 %). These results indicate that the effect of poultry litter physical characteristics on N20 emissions from incorporated applications can be expected to vary depending on the soil water regime.

In the humid southeastern USA, little attention is given to the effect of electrolyte concentration or low levels of Na on clay dispersion, although dispersion‐related phenomenon such as surface crusting and erosion are common. Our objective was to determine the effect of electrolyte concentration, sodium absorption ratio (SAR), and soil pH on saturated hydraulic conductivity of three soils that differed in parent material. Cores packed with sieved soil at different pHs were leached with 10 pore volumes of solution at varying SAR and electrolyte concentrations. The relative decrease in conductivity during leaching was recorded as a measure of clay dispersion and subsequent clogging of pores. The Cecil soil (Typic Hapludult), which is derived from granitic parent material, was easily dispersed and hydraulic conductivity was sensitive to small changes in electrolyte concentration, SAR, or pH. The Davidson (Rhodic Paleudult) and Iredell (Typic Hapludalf) soils, derived from mafic parent material, were flocculated and insensitive to changes in electrolyte concentration and pH except at very high SAR. The implications are that southeastern soils may differ greatly in structural stability and this may be related to parent material. Dispersive soils need to be identified and managed in an appropriate manner.

To predict infiltration in a sealing soil, the seal hydraulic conductivity as a function of time or cumulative rainfall must be known. Few studies have reported measured seal hydraulic conductivities in soils from the southeast USA. Seven Georgia soils packed in columns were subjected to simulated rainfall at an intensity of 50 mm h−1. The sandy loam soils were easily disrupted by rainfall. The calculated seal hydraulic conductivities (Kc) dropped sharply in 10 min of rain and were less than 10% of the initial saturated hydraulic conductivity (Ki) after 45 min. The sandy loam soil with low aggregate stability and Fe content was especially prone to sealing in that Kc dropped to 4% of Ki after 10 min. The well‐structured soil with a clay texture declined in Kc gradually with time, indicating a high resistance to rainfall energy. The sandiest soil showed intermediate resistance to raindrop impact, and Kc leveled off at a high value after 20 min due to the low clay content. The loamy soil with smectitic clay had the lowest Ki and showed little change in Kc with time. Relative seal hydraulic conductivity after 10 or 60 min of rain were good indices differentiating the relative resistance of these soils to surface sealing. A soil stability factor, used to characterize the decrease of Kc in an exponential decay equation, was significantly correlated with water‐dispersible clay on a soil basis.