Characterizing Corn and Cattle Manure Derived Biochars Relevant to Their Use as Soil Additives

Biomass-derived biochars have shown potential for improving soil properties as a whole that are conducive to plant growth with reduced environmental pollution. Four types of biomass, namely, corn stover (CS), dried distillers’ grains and solubles (DDGS), dairy manure (DM), and beef feedlot manure (BFM), were transformed to biochar through pyrolysis at 400°C with 1, 2, or 3 h residence time. The biochars were characterized by proximate analysis (volatile matter (VM), ash, and fixed carbon (FC)), ultimate analysis (total carbon (TC), hydrogen (H), nitrogen (N), sulfur (S), and oxygen (O)), and thermogravimetric analysis (pH, electrical conductivity (EC) and bulk density (BD)). Scanning electron microscopy (SEM), energy dispersion spectroscopy (EDXS), and Fourier transform infrared radiation (FTIR) spectroscopy were used to categorize pore size, functional groups, and mineralogical properties related to potential use in environmental remediation. The highest heating value (HV) was measured with CS (28 to 29 MJ kg-1), and the lowest HV was measured with BFM (~5 MJ kg-1). The greatest organic carbon (OC) content was obtained with CS (68%), followed by DDGS (63%), DM (44%), and BFM (15.4%) biochars. The SEM images showed the macrocellular morphology of the original shape of the biomass particles, which consisted mainly of aggregate microspheres 2 to 10 µm in size. The surface functional groups of all four biochars were dominated by hydroxyl, methyl, methylene, aromatic carbonyl/carboxylic, and alkene groups. The CS and DDGS biochars showed higher TC (76%), FC (61%), OC (67%), water holding capacity, and mineral contents and outperformed the DM and BFM biochars as the best soil amendments. Keywords: Beef feedlot manure, Corn stover, Dairy manure, Dried distillers’ grains and solubles.

Ammonia emissions from land-applied beef cattle manure

Ammonia (NH3) is emitted in vast quantities from exposed livestock manure. The volatilisation of NH3 from livestock manure is a loss in valuable nitrogen in land-applied manure that could otherwise be used for crop production. Ammonia loss to air is also affiliated with environmental problems when it is deposited to the surrounding landscape. The goal o f this study was to quantify the effect of managing beef cattle manure on NH3 emissions of land-applied manure. Three trials were conducted where beef feedlot manure was applied. The NH3 losses were measured from field plots (90 or 160 m2) using acid traps (passive flux samplers). Immediately after applying manure, irrigating with 6 mm of water reduced NH3 loss by 21–52% while tillage (to 15 cm depth) reduced the loss by 76–85% compared with leaving the manure spread on the soil surface. Piled manure that was applied to the land lost 27% less NH3 than did manure taken directly from the pen. There was little NH3 lost from compost that was applied to land since the applied available-N was very low relative to the pen and piled manure. Our study shows that management of livestock manure has a direct impact on NH3 loss to air. It follows that significant reduction in NH3 volatilisation can benefit agriculture and reduce agriculture’s impact on the environment. Key words: Ammonia, manure, tillage, irrigation, compost, feedlot

Carbon, ash and organic matter relationships for feedlot manures and composts

Composting is increasingly recognized as a means of handling livestock manure. Using relationships derived from a dataset of >3000 samples representing the decay spectrum from raw manure to mature compost (from unpaved feedlot pens bedded with straw or wood residuals) we propose that measurement of either total carbon or ash content is sufficient to estimate carbon, organic matter and dry matter mass changes during composting of beef feedlot manure. Key words: Compost, carbon, ash content, feedlot manure