Antonin Kintl

Contemporary agriculture has to face many challenges that are connected with climate change but also with the intensive form of farming. Soil erosion, loss of biodiversity, droughts, soil degradation and pollution with heavy metals (HM) are only a few of the problems. In the presented study, the term “heavy metals” is used operationally to denote metallic elements (Cr, Cd, Cu, Ni, Hg, Zn and Fe), investigated in relation to their accumulation in plant biomass and their potential effects on the process of anaerobic digestion. The use of mixed cropping systems can be an efficient tool to reduce some of these negative aspects. In this study, a possible use of the mixed cropping system (MCS) including Zea mays and Phaseolus vulgaris for phytoremediation processes and methane production was assessed in a two-year experiment. The crops were grown on fields with naturally abundant HM. The HM were accumulated more in legumes than in maize variants. There were no significant differences between HM concentrations in the pure maize culture (M) and maize grown in the MCS. The highest biological accumulation coefficient (BAC) was observed in Cd (1.06) in Variant M in 2021. The calculated theoretical methane yield (TMY) per field growth area (m3/ha) indicated that using the MCS composed of maize and bean led to a higher theoretical methane yield. TMY of the MCS was higher than TMY of the pure maize culture (M) on average by 9.61% in 2020 and by 28.07% in 2021.

A 19-week pot study with unplanted arable topsoil evaluated the decomposition of six incorporated cover crop biomasses such as Egyptian clover, pea, phacelia, sunflower, safflower, and white mustard. The biomasses were pre-rinsed with water (control) or with two non-ionic wetting agents including Mero 33528 (rapeseed fatty acid methyl esters + tridecyl alcohol ethoxylate) and Trend® 90 (isodecyl alcohol ethoxylate). Mass loss of biomasses was significant, ranging from ~90% (safflower) to ~60% (sunflower, white mustard). Wetting agents did not systematically enhance the decomposition but redirected the microbial functioning. Mero consistently enhanced enzyme activities, increased total soil N, and lowered microbial C-limitation indices. By contrast, Trend® 90 dampened the enzymatic activity and exerted neutral or negative effects on N cycling and stoichiometric indicators. Both agents reduced bacterial biomass compared to water-rinsed residues, while fungal responses were crop-dependent, consistent with soil C gains observed under Mero. Despite the primary hypothesis, not the wetting agents but the residue quality (C:N ratio) was the primary driver of decomposition efficiency, while wetting agent chemistry modified microbial pathways without materially altering the bulk mass loss.

The decreasing dependence of electric energy generation on fossil resources and the need of efficient storage and handling of resources for its production lead to the ever‐increasing support of biogas. Systems of using renewable energy sources (RES) depend on the production of plant biomass whose yields may be impaired by the climate change, namely by fluctuating temperatures and unevenly distributed rainfalls in the growing period. This study brings an analysis of the composition of elements and nutrient contents in sugar beet tops and their parts in order to find out whether the sugar beet tops can be used as a substrate suitable for methane production in biogas plants (BP). Based on the obtained results, a theoretical methane yield (TMY) was calculated using three different methods. TMY calculated using a stoichiometric equation ranged from 287 L/kg _VS (crown without leaves) to 354 L/kg _VS (leaves), which is comparable with the methane yield mentioned in the literature for maize. Comparing different methods of the calculation of TMY from sugar beet tops, it was found out that TMY determined by means of stoichiometric equation based on the contents of C, O, H, S and N might be less accurate in the case of sugar beet. More accurate TMY estimates can be achieved by using TMY calculation methods based on the content of simple carbohydrates, proteins and lipids in sugar beet tops or methods with the calculation based on a partial elimination of the part of organic matter with a low rate of biodegradability. TMY calculations have to take into consideration the share of leaves and tuber crowns in the biomass of fresh beet tops as there are great differences in their biodegradability, which might lead to inaccurate results.

A sustainable pathway for valorizing the growing volume of lignin-rich organic feedstocks (LRFs) in emerging economies is to convert them into biochar to sequester carbon and improve soil fertility. However, biochar derived from such LRF may not always show favorable outcomes during soil application. Their interaction with the soil–plant–microbial ecosystem is very complex, and comparative investigations with other common types of biochars are lacking. This study investigated the impact of walnut shell biochar (WSB) and wood chip biochar (WCB) on soil biological properties and crop yield during the growth of Solanum lycopersicum L., and compared them with those of plant waste biochar (PWB) derived from agricultural plant residues. Among biochar variants, only PWB (1% w/w) has increased tomato yield compared to unamended soil. It also showed better carbon mineralization that stemmed from its higher degradability, lower carbon content, and higher H/C ratio. In contrast, WSB showed a relatively higher hydrophobicity, carbonization, and aromaticity that reduced its accessibility to soil microorganisms. Despite these characteristics and higher ash content, WSB did not lower soil enzyme and microbial activity, unlike WCB. At the same time, WSB did not improve crop yield. Mixing WSB (3% w/w) with soil has slightly enhanced the soil carbon stabilization. The high carbon recalcitrance of LRF may necessitate longer aging in soil compared with PWB to showcase any measurable (short/long) benefits to crop yield and soil characteristics.

Manure amendment is a viable strategy to counteract declining soil fertility and degradation. However, existing studies often fail to comprehensively evaluate how different manure types and application methods affect soil health and crop yields. To address this gap, a six‐year‐long field experiment was conducted on Chernic Phaeozem soil, examining the effects of manure amendments in four experimental variants: a control field with only mineral fertilizers (NPK) and three fields treated with poultry, cattle and swine manure in combinations with NPK. Soil biochemical properties such as carbon (C) and nitrogen (N) contents, dehydrogenase activity (DHA), basal respiration (BS) and substrate‐induced respirations (SIR) were assessed at two depth intervals (0–10 cm and 10–20 cm). All manure treatments significantly increased C and N contents in the 0–10 cm as compared to the control. Both poultry and swine manures increased C, N contents in 0–10 cm and 10–20 cm by approximately +24%, +22% and 13%, 10%, respectively, while the effect of cattle manure was rather intermediate (+10%, 11% and + 1%, 4%, respectively). In the 0–10 cm, DHA was higher in plots treated with the poultry (+80%) and cattle (+125%) manures, as compared to the swine manure treatment. In the 10–20 cm, poultry manure resulted in higher C (+6%) and N (+12%) contents, compared to swine manure, while the contents in cattle manure‐treated plots were similar to the control. Swine manure showed the highest increase in manure‐related C and N stocks across both depth intervals (+18% and 69%, respectively), despite no significant effects on soil biological activity (DHA, BR and SIR). Over the entire experiment period, all manure treatments significantly increased crop yields by 0.5 t cereal units ha ⁻¹ year ⁻¹ The poultry and swine manure amendments of soil biochemical properties and crop yields emphasize their value for sustainable soil management. We emphasize the need for site‐specific strategies to maximize the benefits of manure amendments for sustainable agriculture.