Small-plot Experiments Research Articles

Sewage sludge compost as an alternative source of phosphorus to rye in acidic sandy soil

Today, the use of chemical fertilisers is significantly determined by their production and purchase costs, which are high. In contrast, phosphorus (P) is present in sewage sludge in a form that is easy for plants to absorb. Good quality sewage sludge compost (SSC) could contain a high quantity of P, together with other macro- and microelements and organic matter. The effect of regular SSC application on soil characteristics as well as plant parameters has been studied since 2003 in Nyíregyháza in a small plot experiment. Focusing on the P in the soil-plant system, our hypothesis was that SSC covers plants’ P demand through enhancing soil P content and its plant availability in the acidic sandy soil. The effect of the SSC was examined at the doses of 0, 9, 18, and 27 t ha-1 on rye as a test crop. Some soil chemical parameters (pH, soil organic matter - SOM, ammonium lactate (AL) extractable P2O5), and the relationship between plant development (green weight, shoot length), physiological parameters (SPAD index), plant shoot P content, and soil available P content were studied. The obtained data indicated that the SOM content, pH, and available P content of the treated plots increased as a result of the long-term applied SSC compared to the control. Measurement of the relative chlorophyll content showed a strong correlation with the available P content of the soil, but surprisingly less correlation with shoot P content was found. The results of plant biomass and soil P content proved that SSC could be used as a low-cost and good source of P for plants.

Effects of organic amendments on yield determining properties and macronutrient content of maize

The use of organic fertilization is declining in Hungary due to the sharp fall of livestock stand since the middle of the 1980s. Most farmers are forced to use solely chemical crop enhancers. A bifactorial small plot experiment was carried out between 10 May 2023 and 19 October 2023 in Keszthely, in order to examine the effects of farmyard manure (M), green manure (GM) and stem residues (SR) on the nutrient uptake and nitrogen utilization efficiencies of maize at equidistantly increasing (0–70–140–210–280 kg N ha–1) nitrogen doses. The relationship between some vegetative traits (dry biomass weight, Leaf Area Index (LAI)) and yield, furthermore leaf relative water content (RWC) was also examined. According to the results, organic fertilizer substitution significantly increased the N content both in whole plant and grain samples of NPK+M and NPK+GM+SR treatments, compared to the chemically fertilized control (NPK). In case of P and K only slight differences were observed. Whole plant K contents of NPK+M were significantly higher than in the other treatments (P = 0.045; P = 0,005), furthermore P contents in grain samples were significantly higher in NPK+M (P = 0.004) and NPK+GM+SR (P = 0.05) than in control. Harvest index (HI [%]) of NPK+M and NPK+GM+SR were 1.06 and 1.05 times higher than in NPK. Depending on the treatment, P0023 maize hybrid absorbed 58.7–74.64% of total N uptake in the grain (HIN%), and the utilization of 1 kg N fertilizer for the extra yield above the yield of the individual control was 0.39–1.38 kg (AREN). Significant positive correlations were observed between dry biomass weight and yield (NPK: r = 0.937, P = 0.019; NPK+M: r = 0.971, P = 0.006; NPK+GM+SR: r = 0.88, P = 0.049), furthermore LAI and yield (NPK: r = 0.9, P = 0.037; NPK+M: r = 0.983, P = 0.003; NPK+GM+SR: r = 0.784, P = 0.117). Highest RWC values – which may be related to better soil aggregate stability – were measured in NPK+GM+SR treatment, therefore there may be a great potential in this treatment among drought conditions. The effect of organic amendments is particularly noticeable with smaller nitrogen doses so they should be used to reduce inorganic fertilizer application and the resulting environmental risks.

Impacts of conservation agriculture on soil C and N stocks and organic matter fractions: comparing commercial producer fields with a long-term small-plot experiment in Brown Chernozems of Saskatchewan

Conservation agriculture (CA) is increasingly promoted to build soil organic matter (SOM) based on findings from predominantly small-plot long-term agroecosystem experiments (LTAEs), with minimal on-farm data. Using commercial producer fields ( n = 20) in the Brown Chernozemic soil zones of Saskatchewan, Canada, which were sampled before (1996) and after (2018) adopting direct-seeding and continuous cropping (1997), we examined changes in soil organic carbon (SOC) and soil total nitrogen (STN) stocks, along with C and N stocks in particulate (POM) and mineral-associated organic matter (MAOM), and compared them to an LTAE in the same soil zone. After 21 years, SOC and STN stocks (0–30 cm depth) increased by 13% and 21%, respectively, in commercial producer fields, and were more pronounced in finer- than coarser-textured soils. Conversely, there were no significant changes (0–30 cm depth) after 18 years (1998–2016) with CA (continuous wheat and pulse-wheat under no-tillage (PW-NT)) in the LTAE, except that STN stock for PW-NT decreased by 7.7%. The estimated rate of change to 30 cm depth was similar between the commercial fields and LTAE for SOC (0.28 and 0.16 Mg C ha−1 year−1, respectively), but not STN (0.04 and −0.03 Mg N ha−1 year−1, respectively). Changes were more evident in the MAOM than POM fraction in both cases. Although the impact of CA may be similar, as observed for SOC, actual on-farm changes will depend on site-specific factors, and specific CA practice. Therefore, on-farm monitoring studies are needed for more accurate assessments of SOM changes and C sequestration potentials.

ИССЛЕДОВАНИЕ ФУНГИЦИДНЫХ СВОЙСТВ БАКТЕРИЦИДНОГО ПРЕПАРАТА ДЛЯ ЗАЩИТЫ ВИНОГРАДА ОТ МИЛДЬЮ

The paper presents the results of studies of fungicidal properties of bactericidal drug on vine plantations. To test the drug, we used a small-plot experiment with plants of Cabernet Sauvignon variety, cultivated in cover crop with a long-armed bush form. The bactericidal drug contained polyhexamethylene guanidine hydrochloride 9% and alkyldimethylben-zylammonium chloride 1% as active ingredi-ents, as well as functional components and wa-ter. The experiment included variants of differ-ent concentrations of the bactericidal drug (1, 3, 5%), a standard variant using approved fun-gicides (Kurzat, Poliram DF) and a control var-iant − without treatments. The drug at a con-centration of 5% with weak development of downy mildew restrained the development of the disease, with average and epiphytotic de-velopment it was little effective. The effective-ness of the bactericidal drug in protecting against downy mildew at concentrations of 1 and 3% has not been proven. There were no signs of phytotoxicity on vine plants after using the bactericidal drug at the studied doses.

Foliar- and Seed-Applied Insecticides for Management of Melanaphis sorghi (Hemiptera: Aphididae) in Alabama

Abstract Following the emergence of Melanaphis sorghi (Theobald) (Hemiptera: Aphididae) as a new pest of sorghum in the United States, research was conducted to identify tools and techniques successful at reducing populations and preventing economic losses in grain sorghum, Sorghum bicolor (L.) Moench. The objective of this study was to assess the efficacy of seed- and foliar-applied insecticide treatments for management of M. sorghi. Small plot experiments were replicated at two locations to evaluate residual activity of neonicotinoid seed treatments and foliar insecticides. Natural enemy presence was recorded in each of these trials to determine which predator and parasitoid species were using M. sorghi as prey. All seed treatments suppressed M. sorghi populations below a treatment threshold of 75 aphids per plant for 30% of plants for >6 weeks after planting. Foliar insecticides including flupyradifurone, sulfoxaflor, and thiamethoxam provided 3–4 weeks of population suppression, irrespective of M. sorghi pressure. Fifteen natural enemy species were identified in this study, and community structure varied temporally and geographically. In general, natural enemy species richness was correlated with aphid abundance. We identified the most efficacious insecticides available for management of M. sorghi and determined that they should be compatible with biological control and integrated pest management programs.

Six-year monitoring of pesticide resistance in the Colorado potato beetle (Leptinotarsa decemlineata Say) during a neonicotinoid restriction period.

The Colorado potato beetle (CPB; Leptinotarsa decemlineata) is an important potato pest with known resistance to pyrethroids and organophosphates in Czechia. Decreased efficacy of neonicotinoids has been observed in last decade. After the restriction of using chlorpyrifos, thiacloprid and thiamethoxam by EU regulation, growers seek for information about the resistance of CPB to used insecticides and recommended antiresistant strategies. The development of CPB resistance to selected insecticides was evaluated in bioassays in 69 local populations from Czechia in 2017-2022 and in 2007-2022 in small plot experiments in Zabcice in South Moravia. The mortality in each subpopulation in the bioassays was evaluated at the field-recommended rates of insecticides to estimate the 50% and 90% lethal concentrations (LC50 and LC90, respectively). High levels of CPB resistance to lambda-cyhalothrin and chlorpyrifos were demonstrated throughout Czechia, without significant changes between years and regions. The average mortality after application of the field-recommended rate of lambda-cyhalothrin was influenced by temperature before larvae were sampled for bioassays and decreased with increasing temperature in June. Downwards trends in the LC90 values of chlorpyrifos and the average mortality after application of the field-recommended rate of acetamiprid in the bioassay were recorded over a 6-year period. The baseline LC50 value (with 95% confidence limit) of 0.04 mg/L of chlorantraniliprole was established for Czech populations of CPBs for the purpose of resistance monitoring in the next years. Widespread resistance to pyrethroids, organophosphates and neonicotinoids was demonstrated, and changes in anti-resistant strategies to control CPBs were discussed.

Stability yield indices on different sweet corn hybrids based on AMMI analysis.

Currently, sweet corn is considered an important crop due to its high sugar content and low starch content. Important sugars in sweet corn include sucrose, fructose, glucose, and maltose. The purpose of the present study was to use the yield indices of the eight examined sweet corn hybrids and the correlation of the yield indices together. Concentration is important for consumers in terms of yield indices. The research site was located at the Látókép Experimental Station of the University of Debrecen. The small plot experiment had a strip plot design with four replications. The previous crop was sweet corn; the plant density was 64 thousand/ha. The obtained result indicates that Biplot AMMI based on IPCA1 showed that the DB, NO, GS, and GB hybrids had stability and high performance in terms of yield indices. At the same time, fructose and glucose had stable parameters for the hybrids involved in the study. IPCA1 AMMI biplot showed that the ME hybrid had stability and high performance in terms of iron and zinc as well. IPCA2 AMMI biplot showed that DE, GB, and GS hybrids had stability and the highest performance on yield parameters in the scope of the research. Fructose, glucose, and sucrose had stable parameters on hybrids based on IPCA2. The DB and SE hybrids had desirable performance in Lutein and Zeaxanthin based on the biplot. The DE hybrid had a maximum performance on iron and zinc parameters.

Influence of biological fertilizers on the carrots cultivation and yield

Providing the country’s population with high-quality vegetables remains one of the priority areas for agricultural development. The task of agricultural science in solving this problem is to improve agrotechnological techniques and individual operations of soil cultivation, sowing and harvesting, as well as measures to protect against infections and pests. The purpose of this study was to determine the effectiveness of using biofertilizers when cultivating carrots on gray forest soils of medium loamy granulometric composition. Small-plot experiments to improve the technology for cultivating carrots of the Losinoostrovskaya variety were carried out on the basis of the experimental collection site of the Chuvash State Agrarian University during 2022–2023. To stimulate the processes of growth and accumulation of plant biomass, three-time root and leaf feeding of vegetative plants with biological preparations Microbionic and Gumat EM was used. In the course of monitoring the growth processes of carrots, the accumulation of tops and root crops biomass, the authors recorded positive changes in the reduction of the duration of phenophases and a positive trend in increasing carrot yields. The timing of the onset of bunching and trimming ripeness in carrots in plots using root and leaf fertilizing with biological products was shifted by 2–5 days, the total biomass of aboveground mass and root crops was increased to 36%, the yield and marketability of finished products was up to 43% compared with a control group.

Blooming and Forage Characteristics of Twelve Native Forbs Subjected to Repeated Defoliation

Insect pollinators are in population decline due to environmental and chemical stressors. Including native forbs in pastures could benefit grazers and pollinators; however, their forage and flowering characteristics are not fully documented. The objectives of our research were to evaluate 12 native forbs for persistence, forage mass, nutrient composition, and flowering patterns under repeated defoliation. Twelve species were planted in a small-plot experiment in 2018. Response variables were measured from 2020 to 2022. Annual (partridge pea, PPEA, Chamaecrista fasciculata) and biennial (black-eyed Susan, BESU, Rudbeckia hirta) species established high (p < 0.05) plant populations during the first season; however, the PPEA declined (p < 0.05) in forage mass during 2021. Tall species (Maximilian sunflower, MSUN, Helianthus maximiliani; cup plant, CUPP, Silphium perfoliatum) increased in forage mass, produced high-quality forage, and flowered during early fall. Lanceleaf coreopsis (LCOR, Coreopsis lanceolata) produced consistent (p > 0.05) forage mass and flowered in spring. The purple coneflower (PURC, Echinacea purpurea), Illinois bundleflower (ILBF, Desmanthus illinoensis), and oxeye sunflower (OSUN, Helopsis helianthoides) produced high-quality, consistent (p > 0.05) forage mass and flowered mid-season. Interseeding the BESU, ILBF, PPEA, LCOR, PURC, OSUN, and MSUN or CUPP would produce high-quality forage and floral resources throughout summer.

Efficiency and safety of combined herbicide Avrora, OD for corn protection

Field small-plot experiments were carried out in the Moscow region, Rostov region and the Republic of Dagestan in 2021-2022. Herbicide Avrora, OD (100 g/l mesotrione + 80 g/l amicarbazone + 60 g/l nicosulfuron + 5 g/l aminopyralid) was studied during the two growing seasons. The high biological efficiency of Avrora, OD at the stage of 3-6 leaves of corn and the early growth stages of weeds was established. The optimal herbicide rates, the timing of protective measures, and the sensitivity of certain types of weeds were determined depending on the type of weed in crops to combat annual and perennial weeds. The increased application rate of the tested herbicide up to 1.0 l/ha led to an increase in the effectiveness of the pesticide in the number and weight of weeds and was 92.497.9 and 92.497.8 %, respectively. By the harvesting time, infestation of corn crops in the control decreased to 1617 plants/m2. In the variants with herbicides, infestation of crops did not exceed 8 plants/m2. High yields of green mass in the first zone and corn grains in the second and third soil-climatic zones were noted in all tested experimental variants. The use of Avrora herbicide in the early phases of weed growth on vegetative corn plants does not have a negative effect on crop plants and contributes to yield increases of up to 53.756.2 % when cultivating grain corn and up to 138.5 % when cultivating green mass corn.

THE INFLUENCE OF PENICILLIUM FUNGI ISOLATED FROM SOYBEAN ROOTS ON THE SYMBIOTIC SYSTEM “GLYCINE MAX – BRADYRHIZOBIUM JAPONICUM” AND CROP PRODUCTIVITY

Objective. Identify new strains of Penicillium endophytic fungi by morphological and cultural properties, study their influence on the symbiotic system “Glycine max – Bradyrhizobium japonicum” and soybean productivity. Methods. Microbiological (cultivation of endophytic fungi, preparation of spore suspensions, determination of spore titre in suspensions, light microscopy), gas chromatographic (determination of nitrogenase activity of soybean nodules), vegetation and field small-plot experiments (study of the effect of endophytic fungi on symbiotic and morphometric parameters of soybean plants and crop yield when growing on sod-podzolic soil), statistical. Results. New strains of Penicillium endophytic fungi are attributed to the species P. funiculosum Thom, P. variabile Sopp, P. glauco-lanosum Chalabuda, and P. steckii Zaleski based on their morphological and cultural characteristics. Under the conditions of the vegetation experiment, the positive influence of the studied strains on the symbiotic parameters of soybeans was shown. A tendency towards an increase in the number of nodules versus the control in all variants, an increase in the mass of nodules in the variants when soybean seeds were treated with spores of P. variabile 20173 and P. funiculosum 20312 by 28.4 % and 36.4 %, respectively, an increase in the nitrogenase activity of nodules by 29.8–38.5 % in variants with the use of P. stekii 2204, P. glauco-lanosum 20401, P. variabile 20173 was registered. The results of the study of soybean symbiotic parameters under the conditions of the field experiment generally confirmed the corresponding data of the vegetation experiment. Inoculation of soybean seeds with spores of Penicillium endophytic fungi contributed to an increase of the morphometric parameters of plants, namely: height — by 4.6–6.2 cm in all variants of the experiment, above-ground mass of dried plants — by 11.1–19.0 % when treated with P. stekii 2204, P. glauco-lanosum 20401, P. variabile 20173, mass of dry roots — by 13.2 % and 18.4 % with P. funiculosum 20312 and P. variabile 20173. The results of the field experiment proved the positive influence of new strains of endophytic fungi on soybean yield: when soybean seeds were inoculated with P. variabile 20173, P. funiculosum 20312 and P. stekii 2204, the increase in grain productivity was on average from 11.8 % to 17.3 %. The weight of 1000 grains increased by 3.8–5.1 % in variants using P. variabile 20173, P. glauco-lanosum 20401, P. stekii 2204. Conclusion. Penicillium endophytic fungi, which belong to the species P. funiculosum, P. variabile, P. glauco-lanosum and P. stekii, were isolated from the tissues of soybean roots. It was found that Penicillium endophytic fungi have a positive influence on the functioning of the symbiotic system “Glycine max – Bradyrhizobium japonicum” and soybean yield.

Comparing the yield of maize (Zea mays L.) hybrids in organic and conventional agriculture

The European Green Deal was published by the European Commission in 2019. The main aim of the program is to reach net zero greenhouse gas emissions by 2050, making Europe the first climate-neutral continent in the world. To achieve this, criteria are also set for agriculture: increasing the share of land under organic farming to 25%, reducing the use of fertilisers and pesticides. However, the benefits of organic farming are widely debated. The aim of our study was to compare the yield of maize (Zea mays L.) hybrids bred in Martonvasar in two different cropping environments. The silage yields of 20 different maize hybrids were evaluated in a three replicate small plot experiment in an organic field and an adjacent conventional field. The average green mass yield of the hybrids was 36,58 t ha-1 in the organic field and 43,03 t ha-1 in the conventional. The green mass yield in the organic area was 20% lower than in the conventional area, and the dry matter yield and digestible dry matter yield were about 18% lower. Hybrids of different maturity groups responded differently to organic cultivation. The yields of early hybrids decreased more and late hybrids less in the organic farming compared to the conventional production.

The effect of a microbiological product based on <i>Lactobacillus buchneri</i> on barley growth and productivity in the Vologda region

The purpose of the work was to study the effect of the experimental microbiological product ‘Naturost-Aktiv’, developed on the basis of live bacteria Lactobacillus buchneri, on barley growth and productivity in the Vologda region. The study was carried out during the vegetation periods of 2019, 2020 and 2022 on the experimental field of the FSBIS «Vologda Research Center of the Russian Academy of Sciences», as well as in production conditions on the fields of the APC Collective farm «Peredovoy» (Vologda Region). The product ‘Naturost-Aktiv’ was applied twice, when the seeds of the experimental group were soaked in the working solution (1 ml of the product per 1 liter of water) and the phyllosphere of the plants was sprayed in the tillering phase. Tap water was used as control. As a result, there has been identified an increase in the potential energy supply of barley. The area of an individual leaf of experimental plants exceeded the control by 16 %, and the content of the total chlorophylls (a+b) exceeded by 34–42 %, which contributed to a more active accumulation of dry mass of experimental plants in comparison with the control (duringthe action of the product there was an increase in the dry weight of the plant by 12–65 % relative to the control). The changes in the plant growth processes also affected the grain productivity, which increased by 8–26 % in the variants with the product compared to the control. The results of the production experiment, in general, turned out to be like the results of small-plot experiments. Thus, in the conditions of real management, grain productivity of the barley variety ‘Sonet’ increased by 14 % with the use of the product ‘Naturost-Aktiv’ relative to the control. Grain productivity improvement was associated both with an increase in the number of productive shoots and with an increase in the weight of an individual grain.

Glycerin‐based dispensers of fir oil reduce response of Asian citrus psyllid, Diaphorina citri, to citrus odours

AbstractThe Asian citrus psyllid, Diaphorina citri Kuwayama, transmits the bacterial pathogen associated with huanglongbing, a fatal citrus disease. Alternatives to insecticides for D. citri management are being explored, given the development of insecticide resistance and the lack of efficient biological controls. Essential oils as pest repellents have shown some efficacy in laboratory and field evaluations; however, lack of an effective dispenser for field deployment has prevented their application. In this investigation, we evaluated glycerin‐based dispensers releasing fir (Abies spp.) oil as repellents for D. citri. In olfactometer tests, glycerin dispensers loaded with fir oil at 20% w/w repelled psyllids from citrus odours but did not cause repellency at lower loading dosages. Field evaluations were conducted with dispensers at the 20% loading dosage based on laboratory results. In open‐air cage bioassays, fewer psyllids alighted on trees treated with 2 dispensers per tree than on control trees. Similarly, fewer psyllids were found on mature lime trees in homeowner landscapes treated with 4 dispensers per tree compared to paired control trees. In small plot experiments in commercial grapefruit, psyllid infestation of young leaf flush shoots was reduced in plots treated with at least 250 dispensers/ha compared to untreated control plots. Our results indicate that these glycerin‐based fir oil dispensers can reduce infestation of citrus by D. citri. However, the efficacy observed within replicated small plots of citrus grown in monoculture was judged insufficient to manage this vector as a stand‐alone treatment. Larger scale evaluations at higher loading dosages of fir oil and/or in combination with other management tools are warranted based on the outcomes of these initial experiments.

Effect of preparation based on the bacteria <i>Lactobacillus buchneri</i> on the productivity of clover and timothy mixture

Relevance and methodology. Legume-grass mixtures are a source of complete feed for dairy cattle due to good digestibility and balance of protein, carbohydrates, amino acids and vitamins. We studied the effect of a microbiological fertilizer («Naturost-Aktiv») based on live microorganisms Lactobacillus buchneri on the productivity and nutritive value of clover and timothy grass mixture. The study was carried out by small-scale field experience in the FSBI «VolSC RAS» (Vologda region) in 2019–2022, as well as in 2021–2022 in the production conditions in the fields of LLC «Zazerkalie» (Vologda region).Results. In the small-plot experiment we showed that under the influence of the microbiological fertilizer treatment, the productivity of clover and timothy grass mixture increased by 7–39% depending on the year of vegetation; the total dry biomass collection for 4 years of the study in the experimental version exceeded the control by 16%. Evaluation of the nutritive value of the grass mixture showed that the fertilizer increased the content of fodder units in dry matter up to 10%, also the content of metabolizable energy, crude and digestible protein, sugars increased slightly and the content of fiber decreased. In the conditions of the production experiment under the influence of the microbiological fertilizer the herbafe collection increased by 10–17%, dry mass — by 9–22%. The nutritive value of the total content of fodder units in 1 kg of biomass in the experiment exceeded the control by 6%. The gross yield of fodder units from 1 hectare of the field increased by 9.6 cwt/ha under the effect of «Naturost-Aktiv».

The Effect of Mineral Fertilizers on Soil Respiration in Urban Lawns

Application of mineral fertilizers to regulate microbial respiration and carbon dioxide emissions from urban lawn soils was evaluated due to the need to develop technologies for reducing CO2 emissions and for increasing the C-absorption capacity of natural and anthropogenic ecosystems. The studies were performed in the Botanical Garden of Moscow State University on Leninskie Hills in a small-plot experiment with the fractional application of four types of complex fertilizers (NPKS 27 : 6 : 6 : 2, NPKS 21 : 10 : 10 : 2, NPK 15 : 15 : 15 and NPK 18:18:18 + 3 MgO + trace elements (TE)) at the doses of 60 and 120 kg N/ha during the growing season. We studied the basal respiration (BR) of soils, carbon content of microbial biomass (Cmic) by substrate-induced respiration, and the CO2 emission from soils by the method of closed static chambers. Cmic in soil of the control plot in the summer period was 1300–1450 µg/g. Application of NPKS 21 : 10 : 10 : 2 and NPK 18 : 18 : 18 + 3 MgO + TE at a low dose increased Cmic by 12–35% within the first two weeks, and then it dropped. All types of fertilizers applied for a short period of time increased BR of soils and CO2 emission maximum on the sixth day. After two weeks and onwards, their growth decreased or their intensity dropped to the control values (500 mg CO2 m2/h–1 and 1.5 μg C–CO2 g/h, respectively) and lower. The lowest intensity of CO2 emission, a rise in basal respiration, and an increase in microbial biomass were recorded after the application of fertilizer NPKS 21 : 10 : 10 : 2. The change in the functioning of the soil microbial community detected by the maximal qCO2 was the greatest in case of NPKS 27 : 6 : 6 : 2 application. The dynamics of CO2 emission from the soils of the small-plot experiment from April to October correlated with the soil temperature (rS = 0.66, p < 0.05, n = 135). Emissions of CO2 were minimal for the plot with NPKS 21 : 10 : 10 : 2 in all periods of the study.

THE EFFECT OF MINERAL FERTILIZERS ON SOIL RESPIRATION IN URBAN LAWNS

Due to the need to develop technologies for reducing carbon dioxide emissions and increasing the C-absorption capacity of natural and anthropogenic ecosystems, the possibility of using mineral fertilizers to regulate microbial respiration and CO2 emissions from urban lawn soils was evaluated. The studies were carried out on the territory of the Botanical Garden of Moscow State University on the Lenin Hills in a small-plot experiment with the fractional application of four types of complex fertilizers (NPKS 27:6:6:2, NPKS 21:10:10:2, NPK 15:15:15 and NPK 18:18:18 + 3 MgO + trace elements (TE)) at doses of 60 and 120 kg N ha-1 during the growing season. The carbon content of microbial biomass (Cmic) using substrate-induced respiration was studied, the basal respiration (BR) of soils was estimated, and the emission of CO2 from soils using closed static chambers was determined. Тhe Cmic content in the soil of the control plot in the summer period varied within 1300–1450 μg·g-1. The application of NPKS 21:10:10:2 and NPK 18:18:18 + 3 MgO + TE at a low dose increased the Cmic content by 12–35% for two weeks, then it de-creased. The application of all fertilizers for a short period increased basal respiration of soils and CO2 emission, maximum on the 6th day. Aft er two weeks, the increase in the intensity of BR and CO2 emission decreased or it reached the control values (1,5 μg C-CO2·g-1·h-1 and 500 mg·CO2 ·m-2·h-1 respectively) or less. In the short term, the lowest intensity of CO2 emission and a surge in basal respiration, along with an increase in microbial biomass, were observed with the addition of fertilizer NPKS 21:10:10:2. The greatest change in the functioning of the soil microbial community, revealed by the maximum qCO2, occurred with the introduction of NPKS 27:6:6:2. Th e dy-namics of CO2 emission from the soils of the small-plot experiment from April to October correlated with the soil temperature (rS = 0.66, p&lt;0.05, n=135). In all periods of the study, the minimum CO2 emissions were noted for the plot with NPKS 21:10:10:2 fertilizer.

Tactical use of gibberellic acid and nitrogen fertiliser to improve production of perennial ryegrass and white clover swards

The timing and frequency of exogenous gibberellic acid (GA) application was explored in a cut-and-carry small plot experiment using irrigated Canterbury swards. GA applications (8 g GA/ha/application) replaced urea applications (25 kg N/ha/application) over multiple harvests in late winter, early spring and autumn. Timing and number (1, 2 or 3 applications) of GA application occurred in combinations to test the effect of early (August and February), delayed (September and March) or late (October and April) application of GA. Annual herbage yield was 14.6, 18.3 and 18.3±0.40 t DM/ha/y for the three controls (0, 250 kg N/ha/y and 250 kg N/ ha/y + 80g GA/ha/y respectively). Clover content varied with treatment and time of year and was more abundant in low N treatments. There was a positive relationship between N fertiliser rate and annual herbage yield. There was no relationship between increasing GA rate and annual yield, though there was evidence of annual yield improvements, associated with frequent GA application under low (100 kg N/ha/y) or moderate (150 kg N/ha/y) N fertiliser. In late winter, delaying a single application of GA into spring improved N use efficiency (P&lt;0.01). Tactical use of GA, in place of N fertiliser, can be used to maintain herbage yield.

Effect of cover crops undersown in maize on the mycotoxin content in maize biomass

The effect of growing maize with undersown crops on the content of mycotoxins in maize biomass was studied. Small plot experiments were conducted in 2019 on two sites with different soil and climatic conditions: Žabčice and Troubsko. Three treatments of intermediate crops (Italian ryegrass; Fodder vetch and a mixture of both) were undersown into the space between the rows of maize. The maize was harvested at a dry matter content of 35% at the Troubsko experimental site and 43% at the Žabčice experimental site. After the harvest of maize, samples of green biomass (shreddings) were dried at 60°C and then analyzed for the content of mycotoxins such as deoxynivalenol (DON), aflatoxin (AF,L), and fumonisin (FUM). An average yield of maize shreddings ranged from 16.50 to 21.57 t/ha of dry matter within the individual treatment. The contents of mycotoxins from the sites differed in their statistical significance, and both experimental sites showed the lowest concentrations of AFL in maize shreddings while average concentrations of FUM and DON were always the highest. In most observations, treatments with the undersown crops reached the same values as the control treatment. Only in one treatment (mixture of Italian rye grass and Fodder vetch), an increase in the AFL content (by 0.3 µg/kg) was detected. Based on the performed analyses, it is possible to state that no adverse influence of undersown crops on the occurrence of mycotoxins in maize shreddings was recorded using the chosen methodology of cultivation. Exceeded limit values for the content of mycotoxins in feeds according to 2006/576/ were not recorded.

Combining organic fertilisation and perennial crops in the rotation enhances arthropod communities

Single and combined diversification practices in crop fields and their effects on arthropod predators, decomposers and herbivores have mainly been assessed in small plot and cage experiments. In particular, effects of diversification on arthropod predators and their food resources, such as soil fauna, weed seeds and herbivorous prey in entire crop fields across the growing season, remain unclear. We explored how organic fertilisers, with or without the legacy of perennial ley in the crop rotation, and mineral fertiliser without the legacy of perennial ley, affected below- and aboveground communities in 19 spring cereal crop fields. In each field, we determined the abundance of the soil mesofauna, communities of arthropod prey aboveground and of the predator guilds carabids, staphylinids and spiders. We sampled at three crop stages: tillering, heading and ripening. Weed cover and soil characteristics, such as carbon and nitrogen content, were assessed. For most soil mesofauna groups, the combination of organic fertiliser with the legacy of ley gave highest, organic fertiliser with annual crop rotations intermediate, and mineral fertiliser with annual crop rotations the lowest total abundance. Aboveground arthropod prey abundances were similar across treatments. The legacy of ley increased richness of all aboveground arthropod predators. Staphylinid communities’ abundance increased additively as diversification treatments were combined during tillering of the crop. Increasing organic amendments, alongside the reduced disturbances through inclusion of perennial ley in the rotation, led to more abundant communities below- and aboveground as well as more richness in aboveground predator communities.