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Diversity of Bacterial Communities in Horse Bean Plantations Soils with Various Cultivation Technologies
Modern agriculture should limit its degrading impact on the soils, the natural environment, and the climate. No-tillage soil cultivation technologies, which have been in use for many years and are constantly being improved, are a good example of these actions; although, in-depth studies on their impact on the soil microbial community are currently scarce. The aim of our study was to evaluate the effect of cultivation technology on the soil bacterial community to assess differences that can be reflected in the environmental and agricultural functionality, identifying possible bacterial species with ecological properties. In this context, the composition of bacterial communities (at the phyla, order, class, and species levels) was evaluated under different conditions, such as conventional tillage (CT) (plophing), reduced tillage (RT) (stubble cultivator), strip tillage (ST), and no-tillage (direct sowing on stubble and fallow buffer zone of the experimental field), in a horse bean plantation. Metagenomic methods (next generation sequencing technology, NGS) were used to determine the percentage of individual operational taxonomic units (OTUs). Our study showed that no-tillage cultivation technologies, mainly strip and no-tillage methods, had a positive effect on microbiological communities. In fact, key species related to soil fertility and crop yield, such as Gemmatimonas aurantiaca (a microorganism that reduce nitrous oxide, N2O in soil) and Aeromicrobium ponti (a beneficial species for the soil environment, essential for the proper functioning of the crop agroecosystem), increased in reduced cultivation technologies. These species can determine soil fertility and crop yields, and therefore, they are very important for sustainable and even regenerative agriculture. Further studies of soil samples collected from other crop plantations under different cropping systems may indicate beneficial microbial species that are important for soil fertility.
The Use of a Composition of Bacterial Consortia and Living Mulch to Reduce Weeds in Organic Spring Barley Cultivation as an Element of Sustainable Plant Production
Weed infestation of cereal crops in organic farming is becoming a serious problem in agriculture. Sustainable agriculture requires the search for and implementation of crop management techniques that will reduce weeds without negatively impacting the environment. This research refers to the principles of integrated plant protection in sustainable agriculture, allowing the use of chemical plant protection products to be limited to the absolute minimum. Technology for growing spring barley based on the use of bacterial consortia in combination with living mulch (LM) can be an interesting approach to this problem. The aim of this three-year field research was to determine the effects of bacterial consortia and LM on the level of weed infestation in the organic spring barley crop. Two factors were tested in the experiment: bacterial consortia factors: control (without bacterial consortia); 1—Bacillus megaterium var. phosphaticum and Arthrobacter agilis; 2—Bacillus subtilis, Bacillus amyloliquefaciens, and Pseudomonas fluorescens; and LM: control (without LM); red clover; red clover + Italian ryegrass; and Italian ryegrass. This research demonstrated that the bacterial consortia tested significantly reduced both the biomass and number of weeds, including the following dominant weeds: Chenopodium album, Sinapis arvensis, Elymus repens, and Tripleurospermum inodorum. The use of LM also significantly reduced the weed infestation of spring barley stands. The lowest biomass and number of weeds, with the exception of Elymus repens, were recorded on objects with LM Italian ryegrass in spring barley in combination with bacterial consortium 2. The introduction of cultivation with LM Italian ryegrass or its mixture with red clover and the use of bacteria should be recommended for the practice of sustainable agriculture, which will reduce weeds through an ecological method.
Enhancing Soil Microbial Activity and Spelt (Triticum spelta L.) Yield in Organic Farming Through Biofertilizer and Green Manure Applications
Response of Soil Microorganisms to and Yield of Spelt Wheat following the Application of Bacterial Consortia and the Subsequent Effect of Cover Crops in Organic Farming
In modern agriculture, more and more attention is being paid to the use of microorganisms that can increase crop productivity and quality even under adverse weather conditions. Due to the declining biodiversity of crops and the occurrence of soil erosion and nutrient losses, the introduction of cover crops (CC) can be a positive crop management technique. In the field study presented here, the effect of growing spring barley with CCs applied simultaneously with bacterial consortia on the ratio of the total number of bacteria to actinobacteria (B/A) and the number of fungi in the soil was evaluated. The biomass yield of CCs and the subsequent effect on the yield of spelt wheat grown with the application of bacterial consortia were also evaluated. The bacterial consortia applied included consortium 1, comprising Bacillus subtilis, Bacillus amyloliquefaciens, and Pseudomonas fluorescens, and consortium 2, comprising Bacillus subtilis, Bacillus amyloliquefaciens, Pseudomonas fluorescens, and Azotobacter chroococcum. The CCs were red clover, red clover + Italian ryegrass, and Italian ryegrass. The most favorable B/A ratio and the highest number of fungi were obtained after growing spring barley with a CC consisting of a mixture of red clover and Italian ryegrass when using bacterial consortium 2. These conditions additionally had the most favorable influence on spelt wheat. The combination of such a forecrop with the application of bacterial consortium 2 resulted in the highest yields of spelt wheat.
Consortia of Plant Growth-Promoting Rhizobacteria and Selected Catch Crops for Increasing Microbial Activity in Soil under Spring Barley Grown as an Organic Farming System
In order to protect and remediate soils, organic farming methods have grown in popularity. The aim of the study was to evaluate the effect of rhizobacteria (Bacillus subtilis, Bacillus amyloliquefaciens, Pseudomonas fluorescens) and catch crops (undersown red clover alone, undersown Italian ryegrass alone and a mixture of clover and ryegrass) on the microbiological activity of the soil under organic spring barley. In 2019–2021, a field experiment was carried out on an organic farm, randomly in eight variants, each in three repetitions. The following parameters were analyzed: enzymatic activity of dehydrogenases (DHA), acid phosphatase (PAC) and catalase (CAT), soil fertility index (BIF), and a number of selected physiological groups of microorganisms (molds, bacteria, and actinomycetes). Compared to the control variant (without catch crops and bacteria), the values of DHA, CAT, and BIF increased significantly in the variant in which rhizobacteria and catch crops were used simultaneously. The highest BIF, of 32, was obtained in 2019, after the application of red clover catch crop + Italian ryegrass + rhizobacteria. PAC activity dropped significantly after the application of the bacterial consortium alone and was lower than the control by an average of 30%.
Innovative Spring Barley Cultivation Technology Based on the Use of Microbial Products Together with Living Mulch in Organic Farming
Field research was conducted in Poland in 2019–2021 to determine the effect of microbial products and living mulches on grain yield and grain yield structure elements as well as the biological index of soil fertility (BIF) in spring barley grown in organic agriculture. Two factors were examined: I. microbial products: control (no treatment with microbial products), inoculation with phosphorus-releasing bacteria (Bacillus megaterium var. phosphaticum, Arthrobacter agilis), and co-inoculation (simultaneous inoculation) with phosphorus-releasing bacteria (Bacillus megaterium var. phosphaticum, Arthrobacter agilis) and nitrogen-fixing bacteria (Azospirillum lipoferum Br17, Azotobacter chroococcum); II. living mulch: control (no living mulch—spring barley grown in a pure stand), red clover, red clover and Italian ryegrass, and Italian ryegrass. The study results demonstrated that the highest grain yield at 4.5 t ha−1 with superior structure was produced by spring barley following co-inoculation with phosphorus-releasing bacteria (Bacillus megaterium var. phosphaticum, Arthrobacter agilis) and nitrogen-fixing bacteria (Azospirillum lipoferum Br17, Azotobacter chroococcum). The highest value of the biological index of soil fertility (BIF II) determined at the flowering stage was obtained in plots with spring barley cultivated with the living mulch of red clover mixed with Italian ryegrass or red clover following inoculation with phosphorus-releasing bacteria and nitrogen-fixing bacteria 6.9 and 5.7, respectively.