Douglas D. Malo

Effect of biochar on chemical properties of acidic soil

The effect of biochar addition on the chemical properties of acidic soil such as soil pH, electrical conductivity (EC), cation exchange capacity (CEC), and exchangeable acidity were investigated to determine the liming potential of biochars. This study was conducted by incubating acidic soil (clayey, smectitic, acid, mesic, shallow, Aridic Ustorthent) of pH < 4.80 with biochars for 165 days. The biochars were produced from two biomass feedstocks such as corn stover (Zea mays L.) and switchgrass (Panicum virgatum L.) using microwave pyrolysis (at 650°C). Corn stover biochar, switchgrass biochar, and lime (calcium carbonate) were applied at four rates (0, 52, 104, and 156 Mg ha−1) to acidic soil. Amendment type, application rate, and their interaction had significant effects (p < 0.05) on soil pH, EC, and CEC of acidic soil. Exchangeable acidity was significantly affected by amendment type. Application of corn stover biochar had shown a relatively larger increase in soil pH than switchgrass biochar at all application rates. The ameliorating effect of biochars on chemical properties of acidic soil was consistent with their chemical composition.

Molecular characterization of biochars and their influence on microbiological properties of soil.

The tentative connection between the biochar surface chemical properties and their influence on microbially mediated mineralization of C, N, and S with the help of enzymes is not well established. This study was designed to investigate the effect of different biomass conversion processes (microwave pyrolysis, carbon optimized gasification, and fast pyrolysis using electricity) on the composition and surface chemistry of biochar materials produced from corn stover (Zea mays L.), switchgrass (Panicum virgatum L.), and Ponderosa pine wood residue (Pinus ponderosa Lawson and C. Lawson) and determine the effect of biochars on mineralization of C, N, and S and associated soil enzymatic activities including esterase (fluorescein diacetate hydrolase, FDA), dehydrogenase (DHA), β-glucosidase (GLU), protease (PROT), and aryl sulfatase (ARSUL) in two different soils collected from footslope (Brookings) and crest (Maddock) positions of a landscape. Chemical properties of biochar materials produced from different batches of gasification process were fairly consistent. Biochar materials were found to be highly hydrophobic (low H/C values) with high aromaticity, irrespective of biomass feedstock and pyrolytic process. The short term incubation study showed that biochar had negative effects on microbial activity (FDA and DHA) and some enzymes including β-glucosidase and protease.

Wettability of soil aggregates from cultivated and uncultivated Ustolls and Usterts

Soil organic matter can modify the interaction of clay minerals with water, limiting the rate of water intake of swelling clays and stabilising soil aggregates. Soil structural stability and organic C content usually decrease with cultivation. Faster wetting increases stresses on aggregates and decreases stability. Aggregate wettabilities of prairie soils under 3 different management systems (grassland, no-till, and conventional-till) were compared in the Northern Great Plains of the USA. Six Ustolls and 2 Usterts were selected as replications along the Missouri River. Wettability was measured as water drop penetration time (WDPT) and as rate of water intake under 30 and 300 mm tension. At low tension, aggregates from both cultivated fields and uncultivated grasslands showed similar wettability. Water intake in grass aggregates was attributed to a greater amount of stable pores relative to cultivated aggregates. In cultivated aggregates, slaking created planes of failure that allowed rapid water entry. Differences of wettability between management systems at 300 mm tension (in Ustolls, grasslands had greater wettability than cultivated soils, 0.24 v. 0.17 g water/h.g dry soil) and between soil orders (Usterts had longer WDPT than Ustolls, 2.9 v. 1.7 s) were explained by both clay and organic C contents. Simple measurements of aggregate wettability may be effectively used for soil quality characterisation. Aggregate wettability is a desirable property for agricultural soils when it is related to stable porosity, as may be found in high organic matter soils (e.g. grasslands). Wettability is excessive when fast aggregate wetting results in aggregate destruction as observed in low organic matter cultivated soils.

Optimization of Oxygen Parameters for Determination of Carbon and Nitrogen in Biochar Materials

Recently, there has been increased focus on biochar materials due to their ability to sequester carbon for long-term in soil. In the production of biochar or charcoal, plant biomass is heated in a low or no oxygen environment. This process results in a product with unique characteristics. But there is limited research on the standardization of methods for determining total carbon (C) and nitrogen (N) in the biochar materials whose properties vary by feedstock type and pyrolytic conditions. The objective of this study was to determine the oxygen dosing time (OT) and dose (OD) for total organic carbon (TC) and nitrogen (TN) analysis in biochar materials by dry combustion method (using Vario Max CNS analyzer). Central composite rotatable design was used to determine the effect of five levels of oxygen dosing time (OT) and dosing level (OD) on measurement of total carbon and total nitrogen in four types of plant originated biochars. OT and OD level interaction had significant impact on the measurement of TC and TN in all types of biochar materials. Optimum levels of OT and OD were determined as 103 to 110 sec and 180 to 232 ml/min, respectively.

Assessing the Value of Using a Remote Sensing-Based Evapotranspiration Map in Site-Specific Management

ABSTRACT In the glaciated regions of the northern Great Plains, water - either too much or too little - influences soil development, carbon storage, and plant productivity. Integrating site-specific water variability information directly into management is difficult. Simulation models that employ remotely sensed data can generate hard to measure values such as evapotranspiration (ET). This information can be used to identify management zones. The objective of this study was to determine if the METRIC (Mapping Evapotranspiration at High Resolution and with Internalized Calibration) model, which uses weather station and remote sensing data can be used as a tool in site-specific management. This study was conducted on a 65 ha corn (Zea mays L.) field located in east central South Dakota. The METRIC model used Landsat 7 data collected on August 4, 2001 to calculate ET values with spatial resolution of 30 m. ET values were correlated with corn yield (r = 0.85**), apparent electrical conductivity (ECa; r = 0.71**), soil organic carbon (SOC; r = 0.32*), and pH (r = 0.28*). In the footslope positions, high ET values were associated with high corn yields, SOC, EC a , and pH values, while in the summit/shoulder areas low ET values were associated with low yields, SOC, ECa, and pH values. The strong relationship between ET and productivity was attributed to landscape processes that influenced plant available water, which in turn influenced productivity. Cluster analysis of the ET and EC data showed that these data bases complimented each other. Remote sensing-based ET data was most successful in identifying areas where water stress reduced corn yields, while ECa was most successful in identifying high yielding management zones. Findings from this study suggest that remote sensing-based ET estimates can be used to improve management zone delineation.

The Influence of Biochar Production on Herbicide Sorption Characteristics

Biochar is the by-product of a thermal process conducted under low oxygen or oxygen-free conditions (pyrolysis) to convert vegetative biomass to biofuel (Jha et al., 2010). There are a wide variety of end-products that can be manufactured depending on processing parameters and initial feedstocks (Bridgewater, 2003). The pyrolytic process parameters such as temperature, heating rate, and pressure can change the recovery amounts of each end-product, energy values of the bio-oils, and the physico-chemical properties of biochar (Yaman, 2004).

Predicting Soil Electrical Conductivity of the Saturation Extract from a 1:1 Soil to Water Ratio

ABSTRACT Since 1954, the electrical conductivity of the saturated paste extract (ECe) has been the preferred index for soil salinity. Based on this value, remediation strategies were developed and widely used but this approach is time consuming and not routinely offered by many soil testing facilities. However, many laboratories determine the EC1:1 value of a 1:1 soil to solution ratio extract. The objective of this study was to identify the relationship between ECe and EC1:1 and determine if EC1:1 can be used as a proxy in the northern Great Plains for ECe. Samples were collected across five studies and from AGVISE Laboratory. The samples were analyzed for EC1:1 and ECe. The relationship between the ECe and EC1:1 showed that soil parent materials need to be considered in the conversion of EC1:1 values to ECe values. A failure to consider parent materials in this conversion may have short and long-term sustainability ramifications.