Droughts associated with low or erratic rainfall distribution can cause detrimental crop moisture stress. This problem is exacerbated in the USA’s arid western and southeastern Coastal Plain due to poor rainfall distribution, poor soil water storage, or poorly-aggregated, subsurface hard layers that limit root penetration. We hypothesized that soil physical deficiencies may be improved by biochar applications. Research indicates a single biochar will not serve as a universal supplement to all soils; consequently, biochars may need to be designed with physico-chemical properties that can ameliorate specific soil physical deficiencies. We conducted a laboratory study that examined the effect of biochar on soil moisture retention and aggregate formation. Eight biochars were made from four feedstocks at two different pyrolysis temperature classes ( 500°C; 932°C) and were characterized for their physical and chemical properties. In addition, we included a biochar made using fast pyrolysis of hardwood wastes. All biochars were mixed at 2% w/w with either a Norfolk loamy sand (Fine-loamy, kaolinitic, thermic Typic Kandiudults), a Declo silt loam (Coarse-loamy, mixed, superactive, mesic xeric Haplocalcids), or a Warden silt loam (Coarse-silty, mixed, superactive, mesic xeric Haplocambids). Amended soils were laboratory incubated in pots for up to 127 days. About every 30 days, bulk density was measured and then each pot was leached with 1.2 to 1.3 pore volumes of deionized water. Gravimetric and volumetric soil moisture contents were determined after free drainage had ceased and again 2 and 6 days after leaching. The Norfolk-treated soils were later dry-sieved, and the sum by weight of their 0.5- to 1.0-mm aggregates was determined. In general, the biochar surface area and surface tension increased when produced under higher pyrolytic temperatures (>500°C). After leaching, Norfolk soils treated with switchgrass biochars had the most significant increase in soil moisture capacities. Similar increases were found in the Declo and Warden soils. Formation of 0.5- to 1.0-mm aggregates in the Norfolk loamy sand varied with biochar. Biochars enhanced the moisture storage capacity of the Ultisol and Aridisols thereby potentially reducing the on-set of crop moisture stress; however, the effect varied considerably with biochar feedstock and pyrolysis temperature.

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Biochars impact on soil moisture storage in an Ultisol and two Aridisols

An experiment was conducted to compare the suitability of chicken, pig, and cow manure as feed for larvae of the black soldier fly (Hermetia illucens (L.); Diptera: Stratiomyidae). Newly hatched larvae were inoculated on moistened manure (33% dry matter). Water and dried manure were added three times per week, until the first prepupae appeared. Survival was between 82 and 97%, indicating that the tested substrates were suitable. However, development time was much longer than on the control diet (144-215 vs 20 days). Efficiency of conversion of ingested nitrogen (N-ECI) was higher on pig manure than on chicken and cow manure, while the ECI for phosphorus was highest on cow manure. Substrate nitrogen content decreased in the chicken manure, but were stable in pig and cow manure. Phosphorus concentration, and N:P-ratio decreased in all treatments. Since a large proportion of the nitrogen from the manure (23–78%) was lost, the production system would require an air washer for instance, to make it ecologically sound. Shorter development times are required in order to improve economic viability. Drying of the manure could have decreased its nutritional value due to the destruction of microorganisms and heat-labile vitamins. A production system using fresh manure could result in a considerably shorter development time and increased conversion efficiency.

Nutrient utilisation by black soldier flies fed with chicken, pig, or cow manure

The increased global consumption of chicken products has resulted in the generation of huge amounts of manure Numerous studies emphasized the large potential of this waste as an untapped source of renewable energy through anaerobic digestion (AD) However, intrinsic difficulties, in particular the high N content, induce instable process conditions, including the accumulation of intermediates, and foaming, which reduces methane yields Such issues limit the widespread application of this energy-rich substrate for biogas production The process inhibition by ammonia is usually prevented by reducing the concentration of chicken manure through dilution or by operating the plant considerably below its theoretical reactor capacity However, this process compromises process efficiency, thereby increasing capital investments and operational costs Another option to achieve optimal process performance is co-digestion with less N-rich materials However, co-digestion also has its limitations due to the frequent unavailability of sufficient amounts of C-rich substrates A series of promising technical solutions have been developed to overcome the aforementioned bottlenecks Examples include stripping or membrane extraction as means to reduce ammonia concentration in the fermenter Several full-scale plants employing ammonia removal techniques have been installed recently Latest research also investigated the use of additives, such as zeolites and trace elements, as well as bioaugmentation, to mitigate ammonia inhibition The current study reviews the state of technology as well as recent achievements and perspectives It provides an overview of the different approaches to remove ammonia from AD-process and presents practical examples from China and Europe

Tackling ammonia inhibition for efficient biogas production from chicken manure: Status and technical trends in Europe and China

Soil urease activity and bacterial ureC gene copy numbers: Effect of pH

Inorganic elements in biomass feedstocks can influence thermochemical reactions as well as the resultant char’s elemental, compositional, and thermal characteristics. Chars were produced using slow pyrolysis under low (≤400°C) and high (≥500°C) temperature regimes from sugarcane bagasse, peanut hulls, pecan shell, pine chips, poultry litter, and switchgrass. The chars and raw feedstocks were characterized for their elemental, structural, and thermal properties to ascertain the implications of feedstock selection and pyrolysis temperatures on these properties. Char mass yields from the six feedstocks ranged between 28% and 78% by weight while carbon yields ranged between 44% and 89%. In both instances, lower yields were obtained with increasing pyrolysis temperature. Higher pyrolysis temperatures (≥500°C) resulted in more neutral to alkaline chars possessing greater ash contents and increased aromatic character with narrow O/C and H/C ratios. A significant exponential curve response (r2 = 0.87, P 30 MJ kg−1. The chars’ HHV values inversely correlated to their total ash and Cl content. Lignocelluloses chars had better thermal characteristics and lower ash quality concerns implying suitable service in thermal energy production. In contrast, poultry litter char had greater ash contents, medium HHV values, and contained corrosive inorganic elements, which rendered it problematic as a feedstock for thermal energy generation.

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Compositional and Thermal Evaluation of Lignocellulosic and Poultry Litter Chars via High and Low Temperature Pyrolysis

Proper estimation of the nitrogen (N) content of poultry manure and proper manure handling are necessary to ensure that application rates minimize emissions from the manure and nitrate leaching int...

K.H. Nahm

Papers

Evaluation of the nitrogen content in poultry manure