Ján Horák

Biochars in soils: towards the required level of scientific understanding

Key priorities in biochar research for future guidance of sustainable policy development have been identified by expert assessment within the COST Action TD1107. The current level of scientific understanding (LOSU) regarding the consequences of biochar application to soil were explored. Five broad thematic areas of biochar research were addressed: soil biodiversity and ecotoxicology, soil organic matter and greenhouse gas (GHG) emissions, soil physical properties, nutrient cycles and crop production, and soil remediation. The highest future research priorities regarding biochar’s effects in soils were: functional redundancy within soil microbial communities, bioavailability of biochar’s contaminants to soil biota, soil organic matter stability, GHG emissions, soil formation, soil hydrology, nutrient cycling due to microbial priming as well as altered rhizosphere ecology, and soil pH buffering capacity. Methodological and other constraints to achieve the required LOSU are discussed and options for efficient progress of biochar research and sustainable application to soil are presented.

Evaluation of N2O emissions by DNDC model for sandy loam soils of Danubian lowland

Abstract Except for food production the sector of agriculture contribute significantly to emissions of some Greenhouse gases (GHGs), especially N2O. Agricultural practices (especially increase of N consumption in the sector) are now recognized as a major factor influencing increase of N2O emissions into the atmosphere. Estimates of greenhouse gas emissions from the agricultural sector both at a local and regional level are necessary to create possible mitigation strategies with respect to environmental efficiency and economic possibility. We used the DNDC (DeNitrification and DeComposition) model that simulates a full carbon (C) and nitrogen (N) balance, including different C and N pools, and the emissions of all relevant trace gases from soils as NH3, N2O, NO, NO2 and N2. However, for this study only N2O was considered. Intergovernmental Panel on Climate Change (IPCC, 1997) includes methodologies for calculating both direct and indirect emissions of N2O related to agricultural production. Finally, the mo...

Water stability of soil aggregates and their ability to sequester carbon in soils of vineyards in Slovakia

Soil water-stable aggregation is an important process for carbon sequestration and is a key factor controlling soil sustainability and resilience; therefore, the objectives of the present study were to (1) evaluate the differences in soil organic matter state, its specific and labile fractions and their importance in the formation of water-stable aggregates in vineyard soils differing in their genesis and texture under different soil management (vineyard rows – tilled and grassed in-between strips), and (2) estimate the ability of the vineyard soils to sequester soil organic carbon (SOC) into water-stable macro-aggregates (WSAma). The results showed that the WSAma content of the soils ranged from 47% to 97%. Soils with grasses had a higher SOC and labile carbon (CL) contents than the bulk soil and, as a result, the higher total WSAma content. Soils ranged in a decreasing order in their ability to sequester SOC and CL from bulk soil to WSAma: Haplic and Stagni-Haplic Luvisols > Calcaric Fluvisol = Rendzic Leptosol > Haplic and Luvi-Haplic Chernozem > Dystric and Eutric Cambisols. Our results showed that the maximum ratio of SOC content in WSAma to that in bulk soil was 1.0 at the maximum WSAma content regardless of the soil type. An increase in the ratio above this threshold value (1.0) resulted in a decrease in WSAma content.

Biochar and biochar with N-fertilizer affect soil N2O emission in Haplic Luvisol

Abstract The benefits of biochar application are well described in tropical soils, however there is a dearth of information on its effects in agricultural temperate soils. An interesting and little explored interaction may occur in an intensive agriculture setting; biochar addition may modify the effect of commonplace N-fertilization. We conducted a field experiment to study the effects of biochar application at the rate of 0, 10 and 20 t ha−1 (B0, B10 and B20) in combination with 0, 40 and 80 kg N ha−1 of N-fertilizer (N0, N40, N80). We followed nitrous oxide (N2O) emissions, analysed a series of soil physicochemical properties and measured barley yield in a Haplic Luvisol in Central Europe. Seasonal cumulative N2O emissions from B10N0 and B20N0 treatments decreased by 27 and 25% respectively, when compared to B0N0. Cumulative N2O emissions from N40 and N80 combined with B10 and B20 were also lower by 21, 19 and 25, 32%, respectively compared to controls B0N40 and B0N80. Average pH was significantly increased by biochar addition. Increased soil pH and reduces NO3−

How dose of biochar and biochar with nitrogen can improve the parameters of soil organic matter and soil structure

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The Effect of Different Rates of Biochar and Biochar in Combination with N Fertilizer on the Parameters of Soil Organic Matter and Soil Structure

content seen in biochar treatments could be the two possible mechanisms responsible for reduced N2O emissions. There was a statistically significant increase of soil water content in B20N0 treatment compared to B0N0 control, possibly as a result of larger surface area and the presence of microspores having altered pore size distribution and water-holding capacity of the soil. Application of biochar at the rate of 10 t ha−1 had a positive effect on spring barley grain yield.

The Possibility of Using Digital Images in Assessment of Plant Canopy Development and Weed Spread

Abstract Biochar application to agricultural soils has a significant potential to influence soil resource availability and thus crop performance. A factorial experiment investigating effects of different biochar application rates combined with nitrogen fertilizer was conducted in field conditions on a Haplic Luvisol. The aim of this study was to evaluate the effects of biochar and biochar combined with fertilization on soil organic matter and soil structure parameters. The treatments comprised combinations of biochar application of 0, 10 and 20 t ha−1 (B0, B10 and B20) and 0, 40 and 80 kg N ha−1 of nitrogen fertilizer (N0, N40, N80) applied in a full-factorial design. Biochar application rate of 20 t ha−1 significantly increased soil organic carbon content (SOC) and non-labile carbon content (CNL), but decreased carbon lability (LC). The addition of biochar at 10 t ha−1 together with 40 and 80 kg N ha−1 significantly increased the values of SOC and CNL. On the other hand, B10N80 treatment resulted in a considerable decrease of carbon lability (LC). Overall, the lowest average content of water-stable micro-aggregates was found in the B20N80 treatment and then with B10N0 < B20N40 < B20N0 < B10N80 < B0N0 < B10N40. Biochar applied at 20 t ha−1 increased the critical level of soil organic matter and decreased the crusting index.

Effect of Biochar and Biochar Combined with N-Fertiliser on Soil Organic Carbon Content

Since biochar is considered to be a significant source of carbon, in this work we have evaluated the changes in soil organic matter (SOM) and soil structure due to application of biochar and biochar with N fertilization, and have considered the interrelationships between the SOM parameters and the soil structure. The soil samples were collected from Haplic Luvisol at the locality of Dolná Malanta (Slovakia) during 2017. The field experiment included three rates of biochar application (B0 – no biochar, B10 – biochar at the rate of 10 t ha-1, B20 – biochar at the rate of 20 t ha-1) and three levels of N fertilization (N0 – no nitrogen, N160 – nitrogen at the rate of 160 kg ha-1, N240 – nitrogen at the rate of 240 kg ha-1). The rate of biochar at 20 t ha-1 caused an increase in the organic carbon (Corg) content. The combination of both rates of biochar with 160 and 240 kg N ha-1 also caused an increase in Corg. In the case of B20 the extractability of humic substances carbon (CHS) was 17.79% lower than at B0. A significant drop was also observed in the values of the extraction of humic acids carbon (CHA) and fulvic acids carbon (CFA) after the addition of biochar at a dose of 20 t ha-1 with 160 kg N ha-1. However, both rates of biochar had a significant effect at 240 kg N ha-1. After application of 20 t ha-1 of biochar the content of water-stable macro-aggregates (WSAma) significantly increased compared to control. This rate of biochar also increased the mean weight diameter (MWDW) and the index of water-stable aggregates (Sw) and decreased the coefficient of vulnerability (Kv). The biochar at a rate of 20 t ha-1 with 240 kg N ha-1 the value of MWDW increased and value of Kv decreased significantly. The contents of Corg and CL correlated positively with WSAma, MWDW and Sw and negatively with WSAmi and Kv. The extraction of CHA and CFA was in negative relationship with MWDW. We conclude that the application of biochar and biochar combined with N fertilizer had a positive influence on SOM and soil structure.

Measured and Modeled (DNDC) Nitrous Oxide Emissions (N2O) under Different Crop Management Practices in the Nitra Region, Slovakia

Abstract Nowadays, there are various methods of plant biomass assessment available for the purposes of plant growth analysis. Visual plant coverage assessment is often subjective; the other methods are destructive or require purchasing some special devices. This paper presents the assessment of the possibilities and limitations of using digital images made by conventional digital cameras for the purposes of monitoring of the plant canopy development and weed distribution during a vegetation period using the example from the field experiment established on agricultural land in Malanta at the experimental site of the Slovak University of Agriculture. The study is focused on assessment of the effect of biochar application on gas emission, hydrophysical soil properties as well as plant response and yields and it was established in the spring of 2014. Downward images of corn (Zea mays L.) were taken during four sampling campaigns in the vegetation season 2015. Images were analysed by the BreedPix software that could estimate the portion of green fraction (count of green pixels) and thus the image-derived vegetation index (IDVI). According to the image analysis of photos taken during different sampling dates, it could be concluded that biochar addition had a positive effect on the plant growth (above ground biomass) since all treatments resulted in higher IDVIs at the end of the vegetative growth in comparison to control. Further, we assume that the increasing trend in the crop canopy growth was partially limited by competitive presence of weeds at the beginning of the study. According to our experience, we can recommend the software for temporal and spatial monitoring of agricultural crops development. The usage is limited to early growth stages. Moreover, it can be also used for assessment of the weed coverage.

How Fertilisation Affects Distribution Of Carbon And Nutrients In Vineyard Soil

Abstract An experiment of different application rates of biochar and biochar combined with nitrogen fertiliser was conducted at experimental field on a Haplic Luvisol located in Nitra region of Slovakia during the growing season of spring barley (2014). The aim of this study was to evaluate the effects of biochar and biochar combined with nitrogen fertilisation on the soil organic carbon (SOC). The treatments consisted of 0, 10 and 20 t/ha of biochar application (B0, B10 and B20) combined with 0, 40 and 80 kg/ha N of nitrogen fertiliser applied (N0, N40 and N80). The results showed that SOC content at the beginning and end of the trial was always higher at the plots amended with biochar as compared to control plots (B0N0, B0N40 and B0N80); however, statistically significant effects were observed only at the beginning of the trial as well as at the end of trial in B20N40 treatments. Overall, the highest values of SOC contents were obtained at the beginning as well as at the end of the trial when 10 and 20 t/ha of biochar was applied together with 40 kg/ha N.