Effects of Temperature and Activation on Biochar Chemical Properties and Their Impact on Ammonium, Nitrate, and Phosphate Sorption.

There have been limited studies of how pyrolysis temperature and activation processes alter the chemical properties of biochar and how these changes influence ammonium (NH), nitrate (NO), and phosphate (PO) sorption. This study compared the chemical properties of biochars and activated biochars (ActBC with steam and CO activation) produced by slow pyrolysis at 200 (BC200), 400 (BC400), 600 (BC600), 800 (ActBC200, ActBC400, ActBC600), and 850°C (sulfachar-S enriched biochar with steam activation). Quantitative solid-state C nuclear magnetic resonance spectroscopy and elemental analysis were used to study temperature and activation on biochar chemical properties. The sorption capacity of biochars for NH, NO, and PO were measured by batch sorption experiments. Nuclear magnetic resonance spectroscopy data showed that BC200 contained mainly aliphatic C compounds (86% of O-alkyl) belonging to cellulose and hemicellulose, whereas BC400 and BC600 composition was dominated by fused aromatic C structures, containing 81 and 97% aromatic C, respectively. Increasing pyrolysis temperatures decreased biochar total C but increased its cation exchange capacity, pH, and contents of total N and P, calcium, potassium, and magnesium. The BC200 released NO and PO, whereas sulfachar and ActBC200 sorbed significantly higher amounts NO and PO than BC600 by 83 and 96%, respectively, across aqueous solutions. Sulfachar and BC400 sorbed significantly greater amounts NH than did the other biochars. This study shows that production temperature significantly affects biochar chemical properties and that activation increases NO and PO sorption. These results suggest that activated biochar could be useful for sorbing soil N and P, thereby reducing leaching losses.

Effects of biochar amendments on soil microbial biomass and activity.

Environmental benefits reported in the literature of using biochar as a soil amendment are generally increased microbial activity and reduced greenhouse gas (GHG) emissions. This study determined the effects of amendment with biomass feedstocks (spent coffee grounds, wood pellets, and horse bedding compost) and that of biochars (700°C) produced from these feedstocks on soil microbial biomass (C and N) and activity. Soils were amended with these substrates at 0.75% by weight and incubated for up to 175 d under laboratory conditions. Biochar residual effects on soil microbial activity were also studied by amending these soils with either ammonium nitrate (NHNO, 35 mg N kg) or with glucose (864 mg C kg) plus NHNO. Soil microbial biomass C and N, net N mineralization, and CO, NO, and CH emissions were measured. Amendment with biomass feedstocks significantly increased soil microbial biomass and activity, whereas amendment with the biochars had no significant effect. Also, biochar amendment had no significant effect on either net N mineralization or NO and CH emissions from soil. These results indicate that production of biochars at this high temperature eliminated potential substrates. Microbial biomass C in biochar-amended and unamended soils was not significantly different following additions of NHNO or glucose plus NHNO, suggesting that microbial access to otherwise labile C and N was not affected. This study shows that biochars produced at 700°C, regardless of feedstock source, do not enhance soil microbial biomass or activity.

Application of food industry waste to agricultural soils mitigates green house gas emissions.

Application of organic waste materials such as food processing and serving industry cooking oil waste (OFW) can recycle soil nitrate nitrogen (NO(3)-N), which is otherwise prone to leaching after the harvest of crop. Nitrogen (N) recycling will not only reduce the amount of N fertilizer application for corn crop production but is also expected to mitigate green house gas (GHG) emissions by saving energy to be used for the production of the same amount of industrial fertilizer N required for the growth of corn crop. Application of OFW at 10Mg solid ha(-1)y(-1) conserved 68 kg N ha(-1)y(-1) which ultimately saved 134 L diesel ha(-1)y(-1), which would otherwise be used for the production of fertilizer N as urea. Average fossil energy substitution value (FESV) of N conserved/recycled was calculated to be 93 US$ ha(-1)y(-1), which is about 13 million US$y(-1). Potential amount of GHG mitigation through the application of OFW to agricultural soils in Canada is estimated to be 57 Gg CO(2)Eq y(-1).

Using mushroom farm and anaerobic digestion wastewaters as supplemental fertilizer sources for growing container nursery stock in a closed system.

Wastewaters from farm and composting operations are often rich in select nutrients that potentially can be reutilized in crop production. Liners of silverleaf dogwood (Cornus alba L. 'Argenteo-marginata'), common ninebark [Physocarpus opulifolius (L.) Maxim.], and Anthony Waterer spirea (Spiraeaxbumalda Burvénich 'Anthony Waterer') were grown in 6L containers filled with a bark-based commercial mix. Plants were fertigated daily via a computer-controlled multi-fertilizer injector with three recirculated fertilizer treatments: (1) a stock (control) solution with complete macro- and micro-nutrients, electrical conductivity (EC) 2.2 dS m(-1); (2) wastewater from a mushroom farm; and (3) process wastewater from anaerobic digestion of municipal solid waste. The wastewaters used in both treatments 2 and 3 were diluted with tap water, and the computer was programmed to amend, dispense and recirculate nutrients based on the same target EC as in treatment 1. For comparison, there was a traditional controlled-release fertilizer treatment [Nutryon 17-5-12 (17N-2P-10K) plus micro-nutrients topdressed at a rate of 39 g/plant, nutrients not recirculated]. All three species responded similarly to the three recirculated fertilizer treatments. Growth with the recirculated treatments was similar and significantly higher than that obtained with controlled-release fertilizer. Throughout the study, the EC measured in wastewater-derived nutrient solutions, and also in the container substrate, were similar or close to those of the control treatment, although there were small to large differences among individual major nutrients. There was no sign of nutrient deficiency or toxicity symptoms to the plants. Small to moderate excesses in concentrations of SO(4), Na, and/or Cl were physiologically tolerable to the species.

Papermill biosolids effect on soil physical and chemical properties.

Papermill biosolids (PB) can provide multiple benefits to the soil system. The purpose of this study was to quantify the effects of a high C/N ratio (C/N = 100) de-inked PB on soil physical and chemical properties, including soil bulk density, infiltration rates, wet aggregate stability, total soil carbon, and heavy metal concentrations. Four rates of PB (0, 50, 100, and 150 Mg ha(-1)) were applied annually, for up to 3 yr, on four agricultural soils in Ontario, Canada. Decreases in soil bulk density between 0.27 and 0.35 g cm(-3), relative to the nonamended treatment, were observed in soils receiving PB treatments over 3 yr. Total soil carbon increased within 1 yr on PB-amended soils planted to soybeans but not on soils planted to corn. Hydraulic conductivities (K fs) were greater in all soils receiving PB amendments relative to the nonamended treatment throughout the study. Other properties measured, such as pH and electrical conductivity, were relatively unchanged after 2 yr of PB applications. While some increases in heavy metal accumulation occurred, there were no clear trends observed at any of the sites related to PB rates. The results of this study provide support to the idea that annual applications of PB can add significantly to the stability of soil structure.

Nitrogen fertilizer recommendations for corn grown on soils amended with oily food waste.

Soil and plant indices of soil fertility status have traditionally been developed using conventional soil and crop management practices. Data on managing N fertilizer for corn (Zea mays L.) produced on soils amended with C-rich organic materials, such as oily food waste (OFW) is scarce. Identification of a reliable method for making N fertilizer recommendations under these conditions is imperative. The objective of this research was to evaluate soil NO(3)-N (0- to 30-cm depth) at preplant and presidedress (PSNT) times of sampling for predicting N requirements for corn grown on fields receiving OFW. Experiments were conducted at two locations in Ontario, Canada over 3 yr (1995-1997) where OFW was applied at different rates (0, 10, and 20 Mg ha(-1)), times (fall and spring), and slope positions (upper, mid, and lower) within the same field. Presidedress soil NO(3)-N contents were higher compared with preplant time of sampling under all OFW management conditions. Corn grain yields were significantly affected by OFW management and N fertilizer application rates. Maximum economic rate of N application (MERN) varied depending on OFW management conditions. Presidedress soil NO(3)-N contents had a higher inverse relationship with MERN (r = -0.88) compared with soil NO(3)-N at preplant (r = -0.74) time of sampling. A linear regression model (Y = 180.1 - 8.22 NO(3)-N at PSNT) is proposed for making N fertilizer recommendations to corn grown on soils amended with OFW in this geographical region.

Field-scale application of oily food waste and nitrogen fertilizer requirements of corn at different landscape positions.

Oily food waste (FOG; fat + oil + greases) containing high concentrations of fat, oil and grease is produced by the food service, production, and processing industries. It has a high C to N ratio (90:1) and can recycle soil available N through immobilization and remineralization during its decomposition. Experiments were conducted at a farm (Hillsburg fine sandy loam; Typic Hapludalf) having rolling topography (5 and 9% slope) during 1995 and 1996. Objectives of this study were to (i) examine the variability of available N and corn (Zea mays L.) grain yield at different landscape positions of FOG-amended fields and (ii) determine whether N fertilizer management could be improved by considering the spatial variability of soil NO(3)-N at different landscape positions in FOG-amended fields. A spatial and temporal variability in soil NO(3)-N was observed during both years. Corn grain yields at all N fertilizer application rates were affected by slope position and followed the pattern: lower > upper > or = middle. Nitrogen fertilizer requirements for corn production in conjunction with FOG management were also affected by slope position. Essentially no additional fertilizer N was required for corn production at the lower landscape position. It was estimated that site-specific fertilizer N management on FOG-amended fields could result in an average savings of 51 and 63 kg N ha(-1) (with a potential economical savings of US 42 dollars and US 52 dollars ha(-1)) during 1995 and 1996, respectively.

Nitrogen availability from composts for humid region perennial grass and legume-grass forage production.

Perennial forages may be ideally suited for fertilization with slow N release amendments such as composts, but difficulties in predicting N supply from composts have limited their routine use in forage production. A field study was conducted to compare the yield and protein content of a binary legume-grass forage mixture and a grass monocrop cut twice annually, when fertilized with diverse composts. In all three years from 1998-2000, timothy (Phleum pratense L.)-red clover (Trifolium pratense L.) and timothy swards were fertilized with ammonium nitrate (AN) at up to 150 and 300 kg N ha(-1) yr(-1), respectively. Organic amendments, applied at up to 600 kg N ha(-1) yr(-1) in the first two years only, included composts derived from crop residue (CSC), dairy manure (DMC), or sewage sludge (SSLC), plus liquid dairy manure (DM). Treatments DM at 150 kg N ha(-1) yr(-1) and CSC at 600 kg N ha(-1) yr(-1) produced cumulative timothy yields matching those obtained for inorganic fertilizer. Apparent nitrogen recovery (ANR) ranged from 0.65% (SSLC) to 15.1% (DMC) for composts, compared with 29.4% (DM) and 36.5% (AN). The legume component (approximately 30%) of the binary mixture acted as an effective "N buffer" maintaining forage yield and protein content consistently higher, and within a narrower range, across all treatments. Integrating compost utilization into livestock systems that use legume-grass mixtures may reduce the risk of large excesses or deficits of N, moderate against potential losses in crop yield and quality, and by accommodating lower application rates of composts, reduce soil P and K accumulation.

Recycling soil nitrate nitrogen by amending agricultural lands with oily food waste.

With current agricultural practices the amounts of fertilizer N applied are frequently more than the amounts removed by the crop. Excessive N application may result in short-term accumulation of nitrate nitrogen (NO3-N) in soil, which can easily be leached from the root zone and into the ground water. A management practice suggested for conserving accumulated NO3-N is the application of oily food waste (FOG; fat + oil + greases) to agricultural soils. A two-year field study (1995-1996 and 1996-1997) was conducted at Elora Research Center (43 degrees 38' N, 80 degrees W; 346 m above mean sea level), University of Guelph, Ontario, Canada to determine the effect of FOG application in fall and spring on soil NO3-N contents and apparent N immobilization-mineralization of soil N in the 0- to 60-cm soil layer. The experiment was planned under a randomized complete block design with four replications. An unamended control and a reference treatment [winter wheat (Triticum aestivum L.) cover crop] were included in the experiment to compare the effects of fall and spring treatment of oily food waste on soil NO3-N contents and apparent N immobilization-mineralization. Oily food waste application at 10 Mg ha(-1) in the fall decreased soil NO3-N by immobilization and conserved 47 to 56 kg NO3-N ha(-1), which would otherwise be subject to leaching. Nitrogen immobilized due to FOG application in the fall was subsequently remineralized by the time of fertilizer N sidedress, whereas no net mineralization was observed in spring-amended plots at the same time.