The carbon, nitrogen, phosphorus, and sulfur (CNPS) ratios of soils are known to be relatively stable parameters, characterizing different land uses. We hypothesized that the long-term application of sewage sludge compost (SSC) would not change these ratios but would increase the concentration of these elements and change the quality of organic matter (OM), as well as soil enzyme activities. Hence, soil chemical and microbiological properties were studied in a 20-year long-term experiment. The plots were grouped into five blocks and treated every third year with SSC at the rates of 0, 9, 18, or 27 t ha⁻¹. Three plants, in a crop rotation, were tested and sown every year as follows: rye, rye with hairy vetch, and maize. The results showed that basic soil parameters (pH, OM content, E4/E6 ratio, NO₃-NO₂-N, AL-P₂O₅, and soil moisture content) were increased, along with the SSC doses in soil for the rye. Similar trends were found in CNPS concentrations, β-glucosidase, and alkaline phosphatase activities, while the acidic phosphatase activity was reduced. The C:N, C:S, and N:S ratios were not affected by the compost application. The main factors of treatment effects were plant-available phosphorus (ammonium lactate (AL)-soluble P₂O₅), total P, and NO₃-NO₂-N, based on principal component analysis. The canonical correspondent analyses revealed that phosphatase activities were affected by C:N, C:P, and N:P ratios and β-glucosidase was correlated with P forms and the E4/E6 ratio, while the soil pH strongly affected all soil enzymes. Based on the alkaline and acidic phosphatase activities, the role of microbes became more important with increasing compost doses in phosphorus mobilization. We conclude that the addition of SSC could improve soil health through increasing the pH, OM, nutrient content, and microbial activity. Also, some elemental ratios have an important role in the regulation of soil enzyme activities.

The treatment of wastewater and the utilization of the by-products of these processes are an important part of the circular economy. The sewage sludge, a result of wastewater treatment, could be used as a material for plant nutrient supply and/or soil-improving products. The city of Nyíregyháza, Hungary, with 120,000 citizens, has a well-planned water treatment plant operated by Nyírségvíz Ltd., which, in cooperation with the Research Institute of Nyíregyháza, developed a municipal sewage sludge compost (SSC). The closed loop of sewage water treatment and the agricultural utilization of its by-product has been developed and managed. The compost product called Nyírkomposzt was planned for acidic sandy soils. Beyond the agronomic benefits, the sustainable and environmentally sound utilization of SSC reduces sewage sludge disposal. This active involvement of a water utility company demonstrates the potential of cross-sectoral cooperation in solving environmental problems. The quality of the compost fits the Hungarian legislation. To study the effects of 0, 9, 18, and 27 t ha⁻¹ doses of compost on acidic sandy soil, a long-term small plot experiment was started in 2003. The cumulative effects of the regular (every third year, last treatment before sampling in 2021) application of the SSC showed positive changes in basic soil properties, depending on the doses used. Increasing values were found in the case of pH from 4.5 to 6, plant available P₂O₅ from 240 to 690 ppm, and plant available K₂O from 180 to 200 ppm. The plant-available zinc and copper content also increased. Soil organic matter and total N content stabilized at around 0.9% and 0.08%, respectively. The grain yields of winter rye also increased in both investigated years. The yields of 18 t ha⁻¹ treatment were about two times higher compared to the control, but only in 2022 was the difference significant. Our findings underscore the potential of well-planned SSC applications to improve the fertility of ploughed, acidic sandy soil, taking into account the theory of the circular economy by utilizing wastes and decreasing landfilling.

This study was conducted in order to understand the effects of land use and soil types on microbial activity and community structure. Soil samples were collected from four different soil types (Solonetz, Solonchak, Chernozem and Gleysol) being used under different land use practices (arable,...

Compost has been used in agriculture for a long time for nutrient supply. However, in recent decades the disease suppressive effects of the compost and its aqueous extracts are in the focus of the research. Several composts and their water extracts were investigated on different plant diseases especially on those caused by soil-borne pathogens all over the world. The mechanisms are not fully understood. Disease suppression by compost and compost extract is attributed to various mechanisms like the presence of antagonistic microbes and unidentified chemical factors, induction of systemic resistance in plants. Probably the components of the studied substances trigger chemical and biological factors in plants. Fusarium species cause wide spectrum of plant diseases, therefore studies of their control are the hot spots of the researches. The control of Fusarium spp. was investigated in the processed literature based on the possible mode of action of composts or compost extracts in various experimental conditions as in vitro, greenhouse, pot and field experiments. The results proved to be very promising so far. In this respect, compost and compost tea could be possible alternatives to the synthetic chemical pesticides in controlling plant pathogens in a more environmentally sound way.

A talajok termékenységének fenntartása az élelmiszertermelés alapja. A termékenység nem csak a felvehető tápanyagok mennyiségét jelenti, hanem szoros kapcsolatban van a talajok mikrobiális aktivitásával, kémiai és fizikai tulajdonságaival is. A talaj mikroorganizmus közösségét -mennyiségét és diverzitását- azonban jelentősen befolyásolja az alkalmazott gazdálkodási rendszer, és változása a talaj termékenységére is hatást gyakorol. Munkánk célja a nyírségre jellemző homok és emellett kisebb területi kiterjedésben található réti talajok mikrobiológiai sajátosságainak és szervesanyag dinamikájának, illetve az ezek közötti összefüggéseknek a vizsgálata volt ökológia és konvencionális gazdálkodási rendszerekben. Különböző mélységből származó talajminták invertáz, kataláz enzim aktivitását és talajkémiai tulajdonságait (pHKCl, szén- és nitrogéntartalom, humusztartalom, nitrit-nitrát-N tartalom), valamint a közöttük fennálló összefüggést vizsgáltuk. A 2012-es év mérési eredményei alapján megállapítható, hogy az invertáz és kataláz enzimek aktivitása, valamint a szén- és nitrogéntartalom a talajban csökkent a mélységgel. Az eltérő talajtípusok és művelési módok jelentős hatással voltak mindkét enzim aktivitására. Homoktalajoknál az ökológiai gazdálkodású, míg a réti típusú talajoknál a konvencionális gazdálkodás alá eső területeken jelentkezett magasabb enzimaktivitás és C, N tartalom.