Activity Of Soil Biota Research Articles

Enhanced plant litter impacts nematode communities and carbon use efficiency in a mixed forest

Abstract Rising temperatures and higher atmospheric CO2 levels can potentially increase plant photosynthesis and boost forest productivity, thereby spurring litter inputs to soils on a global scale. Understanding the feedback loops between increased litter inputs and soil biota activity will allow for better prediction of organic matter and carbon (C) cycling in terrestrial ecosystems. Nematodes represent the full spectrum of trophic groups within the soil biota. Accordingly, we studied the link between nematode metabolic activities and plant litter input. For this, different litter input levels were manipulated in a temperate forest, including control zones without litter, natural litter input zones and zones with double, triple and quadruple amounts of natural litter input. Soil top layers (0–10 cm) were then collected to study the responses of nematode communities. Increased litter input positively influenced the abundance and diversity of nematodes, except for plant‐parasitic species. Higher litter input levels led to an enhancement in the ratio of bacterivores to the total of bacterivores and fungivores. More litter increased the K/r strategist ratio among bacterivores and the corresponding nematode metabolic footprints. More litter also stimulated nematode production and respiration components and improved the carbon use efficiency of bacterivores. Moreover, structural equation modelling revealed the crucial role of bacterivores in influencing soil organic C under increased litter input. In conclusion, our study shows that increased plant above‐ground litter input modifies the taxonomic and functional communities of soil nematodes, ultimately regulating carbon cycling in forest soils. Read the free Plain Language Summary for this article on the Journal blog.

Comparative assessment of copper pollution, bioavailability, and ecological risks in soil-cacao systems under organic versus conventional management

The continuous use of fertilizers and fungicides has triggered copper (Cu) contamination in cacao soils in Ghana, which is a critical issue for the ecological risk and health safety of cacao products. In this study, we investigated Cu pollution, bioavailability, and ecological risk in soil and determined the Cu levels in the cacao nib, shell, and pod husk. Soils were collected at two soil depths (0–15 ​cm and 15–30 ​cm) from 20 cacao farms, under conventional (CCM: chemical-based fertilizers) and organic (OCM: organic-based fertilizers) management practices together with pods. The total Cu concentration ranged from 67.6 to 96.8 ​mg ​kg−1 in OCM and 28.5–33.9 ​mg ​kg−1 in CCM soil, which decreased with soil depth. The enrichment factor revealed minimal Cu enrichment, which was attributed to anthropogenic activity (fungicide and fertilizer applications). The contamination factor and geoaccumulation index values were low for the CCM soils, and moderate for the OCM soils. Both management systems pose a low potential ecological risk to soil biota activity. Bioavailable Cu extracted with CaCl2, NH4OAc, and DTPA was dominant in CCM soil and decreased with soil depth. The Cu concentration in cacao plants decreased in the order of shell > pod husk > nib, with nib-Cu being below the threshold (50.0 ​mg ​kg−1) of contamination. The results from the pairwise correlation analysis show that CaCl2-available Cu is better for evaluating the Cu content in cacao plants. This study reveals the pollution levels associated with cacao management practices, thus providing valuable insights for developing appropriate mitigation strategies.

Interactions between soil structure dynamics, hydrological processes, and organic matter cycling: A new soil‐crop model

AbstractThe structure of soil is critical for the ecosystem services it provides since it regulates many key soil processes, including water, air and solute movement, root growth and the activity of soil biota. Soil structure is dynamic, driven by external factors such as land management and climate and mediated by a wide range of biological agents and physical processes operating at strongly contrasting time‐scales, from seconds (e.g., tillage) to many decades (e.g., faunal activity and soil aggregation). In this respect, positive feedbacks in the soil–plant system may lead in the longer term to soil physical degradation or to the recovery of structurally poor soils. As far as we are aware, no existing soil‐crop model can account for such processes. In this paper, we describe a new soil‐crop model (USSF, Uppsala model of Soil Structure and Function) that accounts for the effects of soil structure dynamics on water and organic matter cycling at the soil profile scale. Soil structure dynamics are expressed as time‐varying physical (bulk density, porosity) and hydraulic properties (water retention, hydraulic conductivity) responding to the activity of biological agents (i.e., earthworms, plant roots) and physical processes (i.e., tillage, soil swell‐shrink) at seasonal to decadal time‐scales. In this first application of the model, we present the results of 30‐year scenario simulations that illustrate the potential role and importance of soil structure dynamics for the soil water balance, carbon storage in soil, root growth, and winter wheat yields on two soils (loam and clay) in the climate of central Sweden. A sensitivity analysis was also performed for these two scenarios using the Morris method of elementary effects, which revealed that the most sensitive parameters controlling soil structure dynamics in the USSF model are those determining aggregation induced by organic matter turnover and swell/shrink. We suggest that the USSF model is a promising new tool to investigate a wide range of processes and phenomena triggered by land use and climate change. Results from this study show that feedback in the soil‐crop system mediated by the dynamics of soil physical and hydraulic properties are potentially of central importance for long‐term predictions of soil water balance, crop production, and carbon sequestration under global change.

Soil Restoration Strategies for Sustaining Soil Productivity: A Review

Soil degradation, characterised by a deterioration in quality and a drop in ecosystem products and services, is a key impediment to obtaining the necessary increase in agricultural productivity. Soil is a living and dynamic organism that degrades when standard agricultural practices are used. Healthy soil is a crucial pillar of sustainability because it provides various ecosystem services in addition to controlling microbial activity, nutrient recovery, and decomposition. In human time spans, soil is a non-renewable resource that is vulnerable to deterioration due to complex interactions between processes, variables, and causes occurring at a variety of geographical and temporal dimensions. Accelerated erosion, depletion of the soil organic carbon (SOC) pool and biodiversity loss, loss of soil fertility and elemental imbalance, acidification and salinization are among the key soil degradation processes. The strategy aims to minimize soil erosion, boost SOC and N budgets, boost soil biota activity and species diversity (macro, meso, and micro), and improve structural stability and pore geometry. Improving soil quality (i.e., expanding the SOC pool, improving soil structure, and boosting soil fertility) can lower the hazards of soil degradation (physical, chemical, biological, and ecological) while also benefiting the environment.

Toxic metal contamination effects mediated by hotspot intensity of soil enzymes and microbial community structure

Metal contamination from mine waste is a widespread threat to soil health. Understanding of the effects of toxic metals from mine waste on the spatial patterning of rhizosphere enzymes and the rhizosphere microbiome remains elusive. Using zymography and high-throughput sequencing, we conducted a mesocosm experiment with mine-contaminated soil, to compare the effects of different concentrations of toxic metals on exoenzyme kinetics, microbial communities, and maize growth. The negative effects of toxic metals exerted their effects largely on enzymatic hotspots in the rhizosphere zone, affecting both resistance and the area of hotspots. This study thus revealed the key importance of such hotspots in overall changes in soil enzymatic activity under metal toxicity. Statistical and functional guild analysis suggested that these enzymatic changes and associated microbial community changes were involved in the inhibition of maize growth. Keystone species of bacteria displayed negative correlations with toxic metals and positive correlations with the activity of enzymatic hotspots, suggesting a potential role. This study contributes to an emerging paradigm, that changes both in the activity of soil enzymes and soil biota – whether due to substrate addition or in this case toxicity – are largely confined to enzymatic hotspot areas.

Soil biological quality in rhizosphere, growth, and yield of upland rice grown on acid soil after amended biochar enriched sap of Kappaphycus alvarezii

Abstract. Rakian TC, Kilowasid LMH, Afa LO, Riskyana A, Nurazizah, Wijayanti Y, Bahrun A, Subair I, Rahni NM, Alam S, Sarawa, Karimuna L. 2023. Soil biological quality in rhizosphere, growth, and yield of upland rice grown on acid soil after amended biochar enriched sap of Kappaphycus alvarezii. Biodiversitas 24: 6780-6792. Biological soil quality is essential in evaluating soil management practices using biochar enriched for upland rice growth on acid soil. Therefore, the study aimed to (i) analyze the effect of biochar-enriched sap of Kappaphycus alvarezii (K-sap) on the abundance of Arbuscular Mycorrhizae Fungi (AMF), bacteria, and protozoa in rhizosphere soil, growth, and yield of upland rice, and (ii) the relationship between the abundance of soil biota and the growth and yield components, as well as straw N, P, and K content on acid soil. Four upland rice were grown on acid soil incubated with biochar-enriched sap for two weeks in pots. Nine treatments of the biochar-enriched sap were tested, namely control, 5% biochar-0% K-sap, 5% biochar-5% K-sap, 5% biochar -10% K-sap, 5% biochar-15% K-sap, 7.5% biochar-0% K-sap, 7.5% biochar-5% K-sap, 7.5% biochar-10% K-sap, and 7.5% biochar-15% K-sap. Each treatment was three replicates in a randomized block design. The results demonstrated that the AMF spores quantity decreased while flagellates increased in the soil rhizosphere. The P and K content increased, the N:P decreased, and P:K ratio varied in the straw of the upland rice. Plant height and total spikelets increased, while root dry weight and roots to shoots ratio (R:S) decreased with biochar enriched. The abundance of AMF spores and flagellates correlated positively and negatively with R:S. Furthermore, R:S was negatively correlated with plant height and total spikelets. Plant height and total spikelets showed a positive correlation, while root dry weight and R:S was negatively correlated with K content in shoot tissue. The P and K contents with N:P ratio and N:P with P:K were negatively correlated. In conclusion, biochar-enriched K-sap effectively regulated the activity and composition of soil biota in the rhizosphere, influencing upland rice's growth, yield, and nutrient balance uptake on acid soils.

Оценка длительного воздействия бессменного выращивания различных сельскохо зяйственных культур на микробные сообщества почвы

The study of soil microbial communities under different agricultural crops (flax, clover, barley, potato, winter rye) grown in permanent cropping and crop rotation was carried out. The effect of permanent cropping and crop rotation on the taxonomic profile of the prokaryotic and fungal components of the soil microbiome was studied. The effect of permanent cropping and crop rotation on the metabolic intensity and stability of soil biota in the absence of mineral and organic fertilisers was assessed. The subject of the research was the long-term experience established in 1912 by Professor A.G. Doyarenko at the Russian State Agrarian University – Moscow Timiryazev Agricultural Academy, founded in 1912 by Professor A.G. Doyarenko. It was shown that the highest OUT (operational taxonomic units) values for fungi were found in soils under fallow and crop rotation. For prokaryotes, however, the crop rotation variant had the lowest number of OTUs. Ascomycetes were found to be the dominant fungal taxon in all samples studied. Prokaryotes were dominated by Proteobacteria and Acidobacteriota, followed by Actinobacteriota and Firmicutes, and Chloroflexi were represented to a lesser extent. Among the archaea, the Crenarcheota phylum was dominant. It was shown that continuous cultivation of crops generally has a negative effect on the functioning of the microbial community. With an optimal metabolic coefficient of 0.2 in monoculture, they reached 0.6. The sustainability of the soil microbial community is reduced by the continuous cultivation of potatoes, flax and clover without organic and mineral fertilizers, as well as by the “perpetual fallow” option. Particularly unfavorable conditions were found in potato monoculture. Continuous cultivation of cereals, especially winter rye, does not lead to a significant decrease in the activity of soil biota and the stability of soil microbial communities. Crop rotation makes it possible to optimize microbiological processes in the soil and to increase the stability of the soil microbial community.

Influence of tillage methods on carbon dioxide emissions in spring wheat crops

The agriculture intensification is associated with an increase in anthropogenic load on arable soils. Tillage leads to disruption of the natural process of soil formation in connection with which the soil biota activity changes and the carbon cycle is disrupted. The purpose of the study is to establish the effects of the tillage method on the carbon dioxide emission in spring wheat crops. The emission of carbon dioxide during the growing season of spring wheat varies significantly depending on the soil processing method and temperature. At the beginning of spring wheat development, the daily emission of carbon dioxide during the dump and subsurface tillage method does not exceed 36.0 and 36.2 CO2 kg/ha using zero technology provides a reduction in production CO2 production to 27.8 kg/ha*day. With an increase in soil temperature by July 24, the daily emission increases on a dump and subsurface background to 105.5 and 106.0 CO2 kg/ha*day, on a zero background to 95.4 CO2 kg/ha*day. In the future, it decreases. The total carbon losses during the dump and subsurface tillage methods are 2829 and 2793 kg/ha, the use of zero tillage technology reduces carbon losses in grain agrocenosis by 18%.

Soil biological activity and its indicators in soil quality monitoring: mini - review

The presented mini-review shows a systematic picture of the biological activity of soils in its connection with physical and chemical properties, and, ultimately, with soil fertility and crop yields. The biological activity of soils is due to the lifetime activity of soil biota, mainly microbiota and root systems of plants, as well as the action of soil enzymes. It has been shown that individual BAP tests can be used as simple and accessible biological fertility indices BFI.

Зміна біотичних властивостей ґрунтів унаслідок сильватизації колишніх сільськогосподарських угідь (Сколівські Бескиди, Українські Карпати)

The article deals with an impact of the former agriculture land abandonment on biotic properties of soils. In order to better comprehend the processes of spontaneous reforestation (sylvatisation) in a mountain region (the Pohartsi boundary, Koziova village, Stryi district, Lviv regionthe (Skolivski Beskydy physiographic region, the Ukrainian Carpathians) four study plots were selected representing the successional sequence: forest → pasture → hay meadow → arable lands. The study revealed that indicators of microbiological activity is positively affected by the forest floor presence. A zone of the highest soil biotic activity coincides with the limits of the humus horizon Н. Getting deeper into soil profile microbiological activity falls manifold due to changes in physical, hydrophysical and physical-chemical soil properties. In the pasture lands that were least affected by the past agricultural activities, we found both increase and decrease in soil biotic properties. This is foremost caused by the environmental changes. Absence of the forest floor, as a major nutrient source, leads to the 30% decrease in the biomass microorganisms while soil pH shift from a largely to moderately acidic reaction causes 1,5-times higher catalase activity. The latter was the highest in the former pasture lands among all study plots and was assessed as “moderate”. Increase in the urease activity was documented, as well. However its highest values were measured in upper soil horizons of both past and present arable lands. Such an increase of the urease activity is caused by application of organic fertilizers. Despite slightly acidic reaction of the soil water extract from upper horizons of ploughed-up soils the catalase activity here decreases up to 2–2.5 times. This is caused by deterioration of hydric and aeration properties of soils due to their compaction. We noted manifold decrease in the С-СО2 production, as well. The most optimal soil parameters were characteristic for the hay meadow plot despite being significantly affected by anthropogenic activities while the succession of ‘arable lands → pasture → hay meadow’ took a path. Similar moderate soil biotic activity was distinguished for the former pasture land plots. This indicates on the self-restoration and self-regulation capacities of natural ecosystems in the region. We concluded that major indicators of soil biotic activity in the past arable lands are the urease activity, microbial biomass, and soil respiration. The catalase activity makes an additional value for soil degradation assessment of the post-agricultural land uses.

Diversity and activity of soil biota at a post-mining site highly contaminated with Zn and Cd are enhanced by metallicolous compared to non-metallicolous Arabidopsis halleri ecotypes.

Hyperaccumulators' ability to take up large quantities of harmful heavy metals from contaminated soils and store them in their foliage makes them promising organisms for bioremediation. Here we demonstrate that some ecotypes of the zinc hyperaccumulator Arabidopsis halleri are more suitable for bioremediation than others, because of their distinct influence on soil biota. In a field experiment, populations originating from metal-polluted and unpolluted soils were transplanted to a highly contaminated metalliferous site in Southern Poland. Effects of plant ecotypes on soil biota were assessed by measurements of feeding activity of soil fauna (bait-lamina test) and catabolic activity and functional diversity of soil bacteria underneath A. halleri plants (Biolog® ECO plates). Chemical soil properties, plant morphological parameters, and zinc concentration in shoots and roots were additionally evaluated. Higher soil fauna feeding activity and higher bacterial community functional diversity were found in soils affected by A. halleri plants originating from metallicolous compared to non-metallicolous ecotypes. Differences in community-level physiological profiles further evidenced changes in microbial communities in response to plant ecotype. These soil characteristics were positively correlated with plant size. No differences in zinc content in shoots and roots, zinc translocation ratio, and plant morphology were observed between metallicolous and non-metallicolous plants. Our results indicate strong associations between A. halleri ecotype and soil microbial community properties. In particular, the improvement of soil biological properties by metallicolous accessions should be further explored to optimize hyperaccumulator-based bioremediation technologies.

Alternative technology of safflower cultivation by sewage sludge use as a fertilizer-ameliorant

The effect of sewage sludge as a fertilizer-ameliorant in the safflower cultivation was studied. Sewage sludge from Volzhskij wastewater treatment plants prepurified by enzyme-cavitation method was used as a fertilizer-ameliorant in the safflower cultivation. It was found that prepurified sewage sludge is environmentally friendly and has a high fertilizing value. The amino acid composition of safflower seeds was studied. The obtained data indicate that sewage sludge introduction made it possible to significantly increase the safflower nutritional value and the soil microbiological activity. It was found that the greatest increase in the safflower crop yields was observed in the case of sewage sludge introduction at a dose of 10 t/ha with chisel tillage. It can be stated that the technology of safflower cultivation proposed by us, including the application of sewage sludge as a fertilizer-ameliorant in combination with the chisel tillage, significantly affects its productivity. The increase in safflower crop yields over the years of the studies was 8.4-15.3%. In general, it can be concluded that sewage sludge has a complex effect on the soil: improves its water-physical, agrochemical and physico-chemical properties, increases the activity of soil biota and the content of organic matter – one of the main indicators of soil fertility.

Resistance of subarctic soil fungal and invertebrate communities to disruption of below‐ground carbon supply

Abstract The supply of recent photosynthate from plants to soils is thought to be a critical mechanism regulating the activity and diversity of soil biota. In the Arctic, large‐scale vegetation transitions are underway in response to warming, and there is an urgent need to understand how these changes affect soil biodiversity and function. We investigated how abundance and diversity of soil fungi and invertebrates responded to a reduction in fresh below‐ground photosynthate supply in treeline birch and willow, achieved using stem girdling. We hypothesised that birch forest would support greater abundance of ectomycorrhizal (ECM) fungal species and fauna than willow shrubs, and that girdling would result in a rapid switch from ECM fungi to saprotrophs as canopy supply of C was cut, with a concomitant decline in soil fauna. Birch forest had greater fungal and faunal abundance with a large contribution of root‐associated ascomycetes (ericoid mycorrhizal fungi and root endophytes) compared to willow shrub plots, which had a higher proportion of saprotrophs and, contrary to our expectations, ECM fungi. Broad‐scale soil fungal and faunal functional group composition was not significantly changed by girdling, even in the third year of treatment. Within the ECM community, there were some changes, with genera that are believed to be particularly C‐demanding declining in girdled plots. However, it was notable how most ECM fungi remained present after 3 years of isolation of the below‐ground compartment from contemporary photosynthate supply. Synthesis. In a treeline/tundra ecosystem, distinct soil communities existed in contrasting vegetation patches within the landscape, but the structure of these communities was resistant to canopy disturbance and concomitant reduction of autotrophic C inputs.

Soil Biota Adversely Affect the Resistance and Recovery of Plant Communities Subjected to Drought

Climate change predictions indicate that summer droughts will become more severe and frequent. Yet, the impact of soil communities on the response of plant communities to drought remains unclear. Here, we report the results of a novel field experiment, in which we manipulated soil communities by adding soil inocula originating from different successional stages of coastal dune ecosystems to a plant community established from seeds on bare dune sand. We tested if and how the added soil biota from later-successional ecosystems influenced the sensitivity (resistance and recovery) of plant communities to drought. In contrast to our expectations, soil biota from later-successional soil inocula did not improve the resistance and recovery of plant communities subjected to drought. Instead, inoculation with soil biota from later successional stages reduced the post-drought recovery of plant communities, suggesting that competition for limited nutrients between plant community and soil biota may exacerbate the post-drought recovery of plant communities. Moreover, soil pathogens present in later-successional soil inocula may have impeded plant growth after drought. Soil inocula had differential impacts on the drought sensitivity of specific plant functional groups and individual species. However, the sensitivity of individual species and functional groups to drought was idiosyncratic and did not explain the overall composition of the plant community. Based on the field experimental evidence, our results highlight the adverse role soil biota can play on plant community responses to environmental stresses. These outcomes indicate that impacts of soil biota on the stability of plant communities subjected to drought are highly context-dependent and suggest that in some cases the soil biota activity can even destabilize plant community biomass responses to drought.

Recovery of Soil Structure and Fine Root Distribution in Compacted Forest Soils

Soil compaction is a major concern in the context of ensuring sustainable forest and agricultural management practices. Productivity gains during the last decades were also achieved by increasing mechanization. This change was associated with growing machine weights and impacts on trafficked soils. Up to now, knowledge about the resilience of compaction phenomena is still poor. At 11 forest sites on compaction-sensitive silt and loam substrates in the federal state of Baden-Wuerttemberg (Germany), fine root distribution, macroporosity, and apparent gas diffusion coefficients were used to characterize the status of recovery from former soil compaction by machine impact. The time span of recovery at the investigated sites ranged from 6 to 37 years. The investigated soil physical parameters indicate the beginning of soil structure recovery in the wheel tracks, comprising the first 10 cm of soil depth at most sites that were trafficked 10 years or more before the investigation. Synchronously with this restructuring, fine root propagation has started to recover in the topsoils. However, a high persistence of damage was observed below that depth. A synoptic interpretation of the data led to the conclusion that time spans up to almost four decades are not sufficient for the restoration of soil functionality in formerly compacted soils characterized by silt loam texture and low activity of soil biota. In view of the long-lasting persistence of the negative compaction effects, soil protection strategies combined with monitoring of their strict compliance must be implemented into forest practice. In case of an insufficient natural recovery potential, active measures to accelerate the regaining of soil functionality in compacted soils at irregular wheel tracks should be considered in order to shorten the time spans of disturbed soil conditions.

Nutritional regime and biological activity of soil depending on copper contamination and the role of diatomite as a detoxifier

Relevance. Modern agricultural production is characterized by an increase in anthropogenic impact on agrocenoses, which poses a threat to obtaining environmentally safe crop production. Among the toxicants, heavy metals are particularly dangerous, along with pesticides. Metals, including copper, which play a dual role in the “soil — plant” system, are absolutely necessary for plants and at the same time highly toxic when received in excess quantities, deserve special influence in this regard.Methods. The study of the amounts of copper was carried out in microfield experiments with artificial soil contamination with copper sulfate (CuSO4 · 5H2O) at the level of 2 MPC, 4 MPC and 10 MPC. The soil of the experimental field is medium-loamy leached chernozem, high-siliceous rock diatomite was used as a copper detoxifier at the rate of 5 t/ha. The experimental crop was spring wheat of the Margarita variety selected by the Ulyanovsk Research Institute of Agricultural Sciences. The repetition of the experiment is fourfold, the location of the plots is randomized, the accounting area of the plots is 1 m2.Results. The threshold value of copper, beyond which the biological activity of chernozems significantly decreases in the conditions of the Middle Volga region, is the level of pollution in the amount of more than 4 MPC. The introduction of diatomite into the soil in its pure form was accompanied by an increase in the activity of soil microorganisms, when combined with copper sulfate — a relative decrease. Artificial contamination with copper did not cause significant changes in the content of humus , phosphorus and potassium compounds in the arable layer. It is shown that the copper content in the soil at the level of 10 MPC led to a significant suppression of the activity of soil biota and a decrease in the yield of spring wheat by 0.58 t/ha, or by 29%.

Does the Introduction of N2-Fixing Trees in Forest Plantations on Tropical Soils Ameliorate Low Fertility and Enhance Carbon Sequestration via Interactions Between Biota and Nutrient Availability? Case Studies From Central Africa and South America

Plant and/or crop growth rely on nutrient dynamics driven by specific soil biota in different environments. This mini-review aims to provide an overview of interactions between soil organisms, nutrient dynamics, and C sequestration. To this end, we investigated published results from three forest plantations (eucalyptus monocultures and mixed plantations with N2-fixing acacia) on tropical nutrient-poor soils. One case study is located in Central Africa (Congolese coastal plains) and two others in South America (Southeastern Brazil). Overall, the studies showed that soil biota activity exerted positive effects on (i) C accretion, as both soil carbon and belowground and aboveground biomass are driven and enhanced by soil biota; and (ii) on nutrient dynamics and biogeochemical cycles in nutrient-poor soil of tropical ecosystems, which are boosted following C accumulation. On the other hand, the pedoclimatic environment may potentially impact soil functioning of mixed-species plantations through its influence on the composition and activity of bacterial communities. Regardless of the potential risk of acacia invasiveness, benefits such as pulp, fuelwood, electric pole and non-timber products supply, have been reported in Central Africa. We, therefore, conclude that including N2 fixing trees in forestry plantations as reported in this mini-review helps strengthen the links between soil biota, nutrient and SOC dynamics in mixed-species plantations on tropical nutrient-poor soils.

Supply of Nutrients of Zonal Soil Subtypes and Macronutrients Balance in Fodder Crop Rotation Links on Irrigation

The paper presents the results of long-term studies aimed to assess the fertility of zonal soil subtypes during irrigation. Besides, the work presents data on soil nutrient supply and the consumption of nutrients by fodder crops. The reproduction management of soil fertility is carried out through a system-based influence on the mineralization and humification of organic matter, the activity of soil biota, the transformation of mineral chemical compounds and the accumulation of available forms of nutrients in the soil. The balance of macronutrients in the links of fodder crop rotation was calculated. The optimal doses of fertilizers were calculated for different levels of the planned harvest in the conditions of Kalmykia. Based on long–term experimental data, the parameters of biological consumption of nutrients by annual fodder crops were substantiated. Their return in the form of plant residues, and balance calculations were performed. When the calculated doses of fertilizers are applied to the planned yield levels, the nitrogen balance is negative, the phosphorus balance is slightly positive or negative, and the potassium balance is persistently negative.

Cellulose-decomposing activity of soil biota in field crop rotations

The article presents the results of long-term experiments to study the biological activity of sod-podzolic soil in field crop rotations. It is established that the greatest activity of cellulose-destroying microorganisms on the natural background of fertility is observed in the II fruit-bearing crop rotation, with the introduction of manure for potatoes -54.7 %. The lowest biological activity of the soil for 90 days was observed in the grain-grass crop rotation (83% of cereals) – 43.4 %. The application of mineral fertilizers at a dose of N60P60K60 for pre-sowing cultivation significantly increases the biological activity of the soil in relation to the non – wind background, and a fairly high rate of decomposition of flax was observed in the second fruit - bearing crop rotation – 24.9% for the first 45 days, 56.8% for 90 days. The correlation analysis (1998-2019) between the average decomposition of linen under crops for the entire growing season and the value of the hydrothermal coefficient (GTC) showed a close direct relationship, which in the first period of exposure (45 days) was 0.87… 0.90, in the second period of exposure – 0.86 … 0.89.

Wastewater silt sludge application in the case of <i>Carthamus tinctorius</i> cultivation on light chestnut soils of the Volgograd Region, Russia

Aim. The aim of research was to study various methods of basic soil cultivation and a domestic wastewater silt sludge application which could possibility be directed to soil fertility saving and increase in crop yields.Materials and Methods. The object of research was a safflower variety called Alexandrite. Experimental variants were carried out according to a 4-fold repetition. Experiment installation, observations and accounting were carried out in accordance with the field experiment methodology named after B.A. Dospehov.Results. Field research was undertaken in order to study the various methods of a basic tillage and a domestic wastewater silt sludge application possibility under arid conditions of the Volgograd region on light chestnut solonetz soils. The amino acid composition of safflower (Carthamus tinctorius) seeds has been estimated. The data from the study of soil microbiological activity and the effect of non-traditional fertilizers on the increase in the activity of soil biota are presented. The crop yields and economic evaluation of the Carthamus tinctorius cultivation were determined.Conclusion. Modern resource-saving soil cultivation technologies and nontraditional fertilizers are required to: maintain the fertility of slightly humus soils in this arid climate zone, increase amino acids levels in plants, increase soil biological activity, as well to increase safflower crop yields. The proposed technical solutions, employing Rancho chisel tillage with as the basic tillage together with the introduction of non-traditional fertilizers-meliorants, provides structural restoration of soil aggregates, intensification of the humus formation process, increase in soil microbiological activity and - as a result - an increase in the yield of the cultivated Carthamus tinctorius crop.