Determining the Stability of Sugarcane Filtercake Biochar in Soils with Contrasting Levels of Organic Matter

Sugarcane filtercake is a nutrient-rich residue produced prior to sugarcane distillation and is commonly disposed of by applying directly to agricultural fields, often causing high decomposition and leaching rates. Transforming this material into biochar could improve its stability in the soil. In this 92-day incubation study, filtercake biochar produced at 400 °C (BC400) and 600 °C (BC600) was used to trace biochar stability when mixed with two soils with different organic matter levels: an agricultural field (1.2% carbon (C)) and a forest (2.8% C) soil. Based on δ13C isotope analysis, biochar decreases in the field soil mostly occurred in the coarse silt fraction. In contrast, biochar decreases in forest soil appeared to be more equally distributed in all particle size fractions. A negative priming effect in biochar-amended soils was noticeable, mainly in the forest soil. Cumulative CO2 emissions were greater in soils with BC400 than in those with BC600 for both field and forest soils, while adding biochar increased CO2 emissions only in field soils. This increase did not appear to affect native soil organic matter pools. High-temperature filtercake biochar could thus be a more stable alternative to the current practice of raw filtercake applications

Earthworm-microbial interactions influence carbon dioxide and nitrous oxide fluxes from agricultural soils

Earthworms are well known to increase decomposition of organic matter and release of plant available nutrients. They can also increase CO 2 and N2O fluxes from the soil by stimulating respiration, denitrification, and nitrification caused by soil microorganisms. The objective of this thesis was to examine the influence of different earthworm species and population numbers on CO2 and N2O fluxes from a corn agroecosystem. In the field study, earthworm treatments had a significant effect on CO2 fluxes, but there was no difference between CO 2 fluxes from the two species (Lumbricus terrestris L., Aporrectodea caliginosa Savigny) or from the two population levels (1x and 2x the naturally-occuring population). Also, the earthworm treatments had no significant effect on N2O fluxes. Since all treatments contained mixed species and similar population levels at the end of the study, it is likely that CO2 and N2O fluxes in the field were affected more by soil temperature and moisture fluctuations than by the earthworm treatments. The study was repeated in laboratory microcosms under environmental control. Again, earthworm treatments had a significant effect on CO2 fluxes, but not on N2O fluxes. Interestingly, the N 2O fluxes from microcosms containing L. terrestris came solely from denitrification, while the N2O fluxes from A. caliginosa microcosms were produced mostly by nitrification. It is not known why these species stimulate different groups of microorganisms that can produce N2O, and this remains to be investigated

Precision for Smallholder Farmers: A Small-Scale-Tailored Variable Rate Fertilizer Application Kit

Precision agriculture technology at the hands of smallholder farmers in the developing world is often deemed far-fetched. Low-resource farmers, however, are the most susceptible to negative changes in the environment. Providing these farmers with the right tools to mitigate adversity and to gain greater control of the production process could unlock their potential and support rural communities to meet the increasing global food demand. In this study, a real-time variable rate fertilizer application system was developed and tested as an add-on kit to conventional farm machinery. In the context of low investment costs for smallholder farmers, high user-friendliness and easy installment were the main concerns for the system to be viable. The system used nitrogen (N)-sensors to assess the plant nutrient status on the spot and subsequently adjust the amount of fertilizer deposited according to the plant’s needs. Test bench trials showed that the add-on kit performed well with basic operations, but more precision is required. Variability between N-sensors and metering systems, combined with power fluctuations, created inaccuracies in the resulting application rate. Nevertheless, this work is a stepping stone towards catalyzing the elaboration of more cutting-edge precision solutions to support small-scale farmers to become successful, high producing agro-entrepreneurs

Determining the Stability of Sugarcane Filtercake Biochar in Soils with Contrasting Levels of Organic Matter

Sugarcane filtercake is a nutrient-rich residue produced prior to sugarcane distillation and is commonly disposed of by applying directly to agricultural fields, often causing high decomposition and leaching rates. Transforming this material into biochar could improve its stability in the soil. In this 92-day incubation study, filtercake biochar produced at 400 °C (BC400) and 600 °C (BC600) was used to trace biochar stability when mixed with two soils with different organic matter levels: an agricultural field (1.2% carbon (C)) and a forest (2.8% C) soil. Based on δ¹³C isotope analysis, biochar decreases in the field soil mostly occurred in the coarse silt fraction. In contrast, biochar decreases in forest soil appeared to be more equally distributed in all particle size fractions. A negative priming effect in biochar-amended soils was noticeable, mainly in the forest soil. Cumulative CO₂ emissions were greater in soils with BC400 than in those with BC600 for both field and forest soils, while adding biochar increased CO₂ emissions only in field soils. This increase did not appear to affect native soil organic matter pools. High-temperature filtercake biochar could thus be a more stable alternative to the current practice of raw filtercake applications.Science, Faculty ofNon UBCEarth, Ocean and Atmospheric Sciences, Department ofResources, Environment and Sustainability (IRES), Institute forReviewedFacult

Impact of Different Agricultural Waste Biochars on Maize Biomass and Soil Water Content in a Brazilian Cerrado Arenosol

Arenosols in the Brazilian Cerrado are increasingly being used for agricultural production, particularly maize. These sandy soils are characterized by low soil organic matter, low available nutrients, and poor water-holding capacity. For this reason, adding biochar as a soil amendment could lead to improved water and nutrient retention. A greenhouse experiment was carried out using twelve biochars derived from four feedstocks (cotton husks, swine manure, eucalyptus sawmill residue, sugarcane filtercake) pyrolized at 400, 500 and 600 °C and applied at 5% w/w. The biochars’ effect on maize biomass was examined, along with their contribution to soil physical properties including water retention, electrical conductivity (EC), and grain size distribution. After six weeks, maize plants in soils with eucalyptus and particularly filtercake biochar had higher biomass compared to those in soils with cotton and swine manure biochars. The latter’s low biomass was likely related to excessive salinity. In general, our biochars showed potential for increasing θ in sandy soils compared to the soil alone. Filtercake and eucalyptus biochars may improve soil aeration and water infiltration, while applying cotton and swine manure biochars at levels <5% to avoid high salinity could contribute to improved soil water retention in Cerrado Arenosols.Science, Faculty ofNon UBCEarth, Ocean and Atmospheric Sciences, Department ofResources, Environment and Sustainability (IRES), Institute forReviewedFacult