Potential of Artemisia dubia Wall Biomass for Natural Crop Protection.

The Green Deal strategy has the very ambitious goal of transforming the European Union into the first climate-neutral continent by 2050. For the agricultural sector, one of the main challenges is to reduce the use of synthetic fertilizers and pesticides. Crop protection measures aim to maintain and ensure certain standards of yield and quality, which are generally achieved by the control of pests, diseases, and weeds. One of the possibilities to reduce the use of pesticides could be allelopathic plants, which are not only potential sources of allelochemicals but also renewable biomass sources. The aim of this study was to analyze the productivity of Artemisia dubia Wall and evaluate the allelopathic effects of biomass on crops and weeds. It was determined that the biomass productivity of A. dubia varied from 2 to 18 t ha-1, depending on how many times it is cut during the growing season and the fertilizer rate. A. dubia has allelopathic properties, which were verified using an aqueous extract and can completely suppress the germination of Taraxacum officinale seeds. Young plants harvested in the middle of summer were characterized by the highest number of phenolic compounds. This shows the strong allelopathic effect of A. dubia biomass on other plants.

Biochar with Inorganic Nitrogen Fertilizer Reduces Direct Greenhouse Gas Emission Flux from Soil.

Agricultural waste can have a catastrophic impact on climate change, as it contributes significantly to greenhouse gas (GHG) emissions if not managed sustainably. Swine-digestate-manure-derived biochar may be one sustainable way to manage waste and tackle GHG emissions in temperate climatic conditions. The purpose of this study was to ascertain how such biochar could be used to reduce soil GHG emissions. Spring barley (Hordeum vulgare L.) and pea crops in 2020 and 2021, respectively, were treated with 25 t ha-1 of swine-digestate-manure-derived biochar (B1) and 120 kg ha-1 (N1) and 160 kg ha-1 (N2) of synthetic nitrogen fertilizer (ammonium nitrate). Biochar with or without nitrogen fertilizer substantially lowered GHG emissions compared to the control treatment (without any treatment) or treatments without biochar application. Carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) emissions were directly measured using static chamber technology. Cumulative emissions and global warming potential (GWP) followed the same trend and were significantly lowered in biochar-treated soils. The influences of soil and environmental parameters on GHG emissions were, therefore, investigated. A positive correlation was found between both moisture and temperature and GHG emissions. Thus, biochar made from swine digestate manure may be an effective organic amendment to reduce GHG emissions and address climate change challenges.

Nitrogen flow in livestock waste system towards an efficient circular economy in agriculture.

The race is on to achieve an important level of efficiency in the attainment of a circular economy in agriculture especially with the aim of sustainable nitrogen management. This cycle in the agricultural sector cuts across livestock farming, agriculture-induced waste generation, recycling and utilization, energy generation, crop production, ecosystem protection and environmental management through the mitigation of climate changes. In this work, we assess the process and functionalities of livestock waste generated from the piggery farm and their combinations with other by-products such as biochar and ash in comparison with mineral fertilization as sources of nitrogen applied in agricultural soil. The experiment was performed in a controlled environment with wheat (Triticum aestivum L.) grown in a neutral and an acidic soil. Pig manure was used as the primary feedstock, fed and processed to biogas and nutrient-rich digestate by the anaerobic digestion process. The results revealed that the co-amendments of pig manure digestate with biochar and ash had complimentary positive effect on measured indices such as mobile potassium, phosphorus, biomass yield and nitrogen use efficiency. The mineral nitrogen fertilizer significantly induced carbon dioxide emissions from day 35 when compared to emissions from the organic amendments. In contrast, the organic amendments influenced nitrous oxide emissions from the onset till day 30 before flattening out. The individual combination of pig manure digestate with biochar and ash had a negative influence on enzymatic activity (dehydrogenase). Soil microbial biomass carbon was induced across all treatments in both soil types. Pig manure digestate + ash and pig manure digestate had 32.1 and 48.8% soil microbial biomass increase in neutral soil and acidic soil, respectively. Overall, the processing and application of single-use amendment or in combination with biochar and ash holds huge potential in the optimization of nitrogen and carbon efficiency towards sustainable soil management via improving soil quality, carbon sequestration and climate change.

The Impact of Swine Manure Biochar on the Physical Properties and Microbial Activity of Loamy Soils.

Biochar has been proven to influence soil hydro-physical properties, as well as the abundance and diversity of microbial communities. However, the relationship between the hydro-physical properties of soils and the diversity of microbial communities is not well studied in the context of biochar application. The soil analyzed in this study was collected from an ongoing field experiment (2019-2024) with six treatments and three replications each of biochar (B1 = 25 t·ha-1 and B0 = no biochar) and nitrogen fertilizer (N1 = 160, N2 = 120 kg·ha-1, and N0 = no fertilizer). The results show that biochar treatments (B1N0, B1N1, and B1N2) significantly improved the soil bulk density and total soil porosity at different depths. The B1N1 treatment substantially enhanced the volumetric water content (VMC) by 5-7% at -4 to -100 hPa suction at 5-10 cm depth. All three biochar treatments strengthened macropores by 33%, 37%, and 41%, respectively, at 5-10 cm depth and by 40%, 45%, and 54%, respectively, at 15-20 cm depth. However, biochar application significantly lowered hydraulic conductivity (HC) and enhanced carbon source utilization and soil indices at different hours. Additionally, a positive correlation was recorded among carbon sources, indices, and soil hydro-physical properties under biochar applications. We can summarize that biochar has the potential to improve soil hydro-physical properties and soil carbon source utilization; these changes tend to elevate fertility and the sustainability of Cambisol.

The Effectiveness of Digestate Use for Fertilization in an Agricultural Cropping System.

The need to find and maximize the use of alternative sources of nutrients for plants and soil environment have been on the forefront of research in sustainable agriculture. These alternatives have to be affordable, accessible, reproduceable, and efficient to compete with established inorganic fertilizers while at the same time reduce any potential negative impacts on the environment. We aimed to evaluate the effectiveness of digestate fertilization in an agricultural system over a period of three years. The digestate utilized in the study consisted of animal waste-based digestates, namely pig manure digestate, chicken manure digestate, and cow manure digestate, and were compared with synthetic nitrogen fertilizer. Every year, the digestate and the synthetic nitrogen fertilizer were split applied at the rate of 90 and 80 kg N ha-1. The soil chemical composition after three years of fertilization showed a slight decrease, significantly different nitrogen and carbon changes while phosphorus and potassium were significantly higher in the digestate treatments. The third year of digestate application showed higher grain yield than previous years and the yield from the digestate treatments were significantly different from the synthetic nitrogen fertilizer. The nitrogen use efficiency for the three years was in the range of 20-25 percent in the digestate treatments, with a strong correlation between the nitrogen use efficiency and the grain yield. There were varied results in the grain quality and straw quality in the digestate and synthetic nitrogen fertilizer with no clear trend observed. Our results showed a relatively high potential of animal waste digestates over the short to mid-term use with a positive result obtained in comparison to synthetic nitrogen fertilizer under favorable climatic conditions.

Granulated biofuel ash as a sustainable source of plant nutrients.

Recovery of nutrients from biomass combustion ash is of great importance for sustainable bioenergy waste use. In this work, granulated fertilizer materials were engineered from biofuel bottom ash, lime kiln dust and water, analysed for their chemical complexity and tested in pot experiments (2017-2018) for their propensity to release nutrients. The results obtained in this work showed that spring barley yield was observed to be the highest for granulated biomass ash with 30% of ash in the granule. The yield increased 3.99 t ha-1 per 100 kg ha-1 potassium oxide (K2O) in 2017 and 1.23 t ha-1 per 100 kg ha-1 K2O in 2018. Straw yield varied between 1.39-5.08 t ha-1/100 kg ha-1 in 2017 and 0.36-1.23 t ha-1/100 kg ha-1 in 2018. Calcium concentration significantly increased in soil. No significant changes in soil mobile phosphorus (P) were obtained as well as for the heavy metal concentrations in soil. This suggests that biofuel ash can be a significant source of certain major nutrients for crops that can also beneficially affect soil pH. The results of this work can provide policy-makers with the information needed to diversify existing and enable new biomass bottom ash utilization routes which currently vary significantly between the countries.