Soil Potassium Content Research Articles

Partition Management of Soil Nutrients Based on Capacitive Coupled Contactless Conductivity Detection

A method based on capacitively coupled contactless conductivity detection (C4D), which has been proven effective for the rapid detection of available soil potassium content, was firstly proposed to apply to soil nutrient detection. By combining a detection signal spectrum analysis, geographic information system (GIS) data, and a cluster analysis, a soil nutrient management system to match the detection device was developed. This system included six modules: soil sample information management, electrophoresis analysis, quantitative calculation, nutrient result viewing, cluster analysis, and nutrient distribution map generation. The soil samples, which were collected from an experimental field in Xuchang City of Henan Province, were analyzed using the C4D and flame photometer methods. The results showed that the detection results for the soil samples obtained via the two methods were in good agreement. C4D technology was feasible for the detection of the soil available nutrients and had the advantages of a high timeliness, low sample volume, and low pollution. The soil nutrient management system adopted the hierarchical clustering method to classify the grid cells of the experimental field according to the nutrient detection results. A soil nutrient distribution map displayed the spatial difference in nutrients. This paper provides a systematic solution for soil nutrient zone management that includes nutrient detection, signal analysis, data management for the nutrient zone, and field nutrient distribution map generation to support decision making in variable fertilization.

Integrated analysis of potential microbial consortia, soil nutritional status, and agro-climatic datasets to modulate P nutrient uptake and yield effectiveness of wheat under climate change resilience.

Climate change has a devastating effect on wheat production; therefore, crop production might decline by 2030. Phosphorus (P) nutrient deficiency is another main limiting factor of reduced yield. Hence, there is a dire need to judiciously consider wheat yield, so that human requirements and nutrition balance can be sustained efficiently. Despite the great significance of biostimulants in sustainable agriculture, there is still a lack of integrated technology encompassing the successful competitiveness of inoculated phosphate-solubilizing bacteria (PSB) in agricultural systems in the context of climatic conditions/meteorological factors and soil nutritional status. Therefore, the present study reveals the modulation of an integrated P nutrient management approach to develop potential PSB consortia for recommended wheat varieties by considering the respective soil health and agro-climatic conditions. The designed consortia were found to maintain adequate viability for up to 9 months, verified through field emission scanning electron microscopy and viable count. Furthermore, a significant increase in grain yield (5%-8%) and seed P (4%) content was observed in consortia-inoculated wheat plants with 20% reduced Diammonium phosphate (DAP) application under net house conditions. Fluorescence in situ hybridization analysis of roots and amplification of the gcd gene of Ochrobactrum sp. SSR indicated the survival and rhizosphere competency of the inoculated PSB. Categorical principal component analysis (CAT-PCA) showed a positive correlation of inoculated field-grown wheat varieties in native soils to grain yield, soil P content, and precipitation for sites belonging to irrigated plains and seed P content, soil organic matter, and number of tillers for sites belonging to Northern dry mountains. However, the impact of inoculation at sites belonging to the Indus delta was found significantly correlated to soil potassium (K) content, electrical conductivity (EC), and temperature. Additionally, a significant increase in grain yield (15%) and seed P (14%) content was observed in inoculated wheat plants. Thus, the present study demonstrates for the first time the need to integrate soil biological health and agro-climatic conditions for consistent performance of augmented PSB and enhanced P nutrient uptake to curtail soil pollution caused by the extensive use of agrochemicals. This study provides innovative insights and identifies key questions for future research on PSB to promote its successful implementation in agriculture.

Soil fertility appraisal of some selected villages in Kirmira block of Jharsuguda District under western-central table land agro-climatic zone of Odisha, India

A soil fertility status inventory work was carried out in some villages of Kirmira block of Jharsuguda district located in the Western Central Table Land Agro Climatic Zone of Odisha, India. Results showed that soil pH ranged between 4.3 and 6.4 and electrical conductivity of the entire study area remained below 1 dSm-1. Soil Organic Carbon (SOC) content ranged between 0.17 to 0.88%. Available nitrogen content in these soils was found to be varied between 84.0 to 398.0 kg ha-1. Available Bray’s phosphorus content varied from 0.75 to 67.10 kg ha-1. Available soil potassium content varied widely from 90 to 500 kg ha-1. CaCl2 extractable soil sulphur varied from 0.14 to 12.49 mg kg-1. DTPA extractable micronutrients (Fe, Mn, Cu and Zn) varied from 32.62 to 192.20, 28.08 to 220.50, 0.48 to 2.86, and 0.56 2.38 mg kg-1 respectively. Hot water soluble boron content ranged from 0.13 to 0.88 mg kg-1. All the figures in the lower range were found in upland soils while the higher values for all the parameters were found in low land soils.

IMPROVEMENT OF SOME SOIL CHEMICAL PROPERTIES ON MARGINAL LANDS TO INCREASE CORN PRODUCTION THROUGH CONSERVATION TILLAGE TECHNIQUES AND ORGANIC FERTILIZERS

This study aims to analyze the effect of applying conservation tillage techniques and a combination of organic and inorganic fertilizers on soil chemical properties on marginal land and maize production. This research was conducted in Jambi Outer City District, Muaro Jambi Regency, Jambi Province, from January to April 2021 using a randomized block design with 15 treatments and 3 replications. Parameters observed were corn plant height at the age of 15 DAP, 30 DAP and 45 DAP, weight of corn cobs, weight of dry shelled corn seeds, Soil pH, Soil C-Organic Content, Soil Nitrogen Content, Soil Phosphorus Content, Soil Potassium Content, Cation Exchange Capacity, Base Saturation. The results showed that the application of conservation tillage techniques and a combination of organic and inorganic fertilizers had a significant effect on corn plant height 45 DAP, corn cob weight, soil pH, C-Organic Soil, Soil Phosphorus Content, Soil Potassium Content, Cation Exchange Capacity.

Intercropping for nutrient retention, profitability, and quality bulb production of garlic (Allium sativum L.) under eastern Himalayan foothills region

A two years experiment was laid out to evaluate the effect of intercropping system for soil nutrient retention, profitability, and quality of garlic. The result revealed that the association of garlic and garden pea system recorded maximum garlic equivalent yield (5.99 t/ha). Highest protein content of the bulb (5.20%) was recorded by the garlic + garden pea system and the maximum reducing sugar (2.08%) was found in the garlic + coriander system. Garlic + garden pea intercropping system recorded significant maximum soil nitrogen (123.52 kg/ha) and phosphorus content (50.37 kg/ha) whereas significant maximum soil potassium content (158.45 kg/ha) was recorded in sole coriander plots. However, production economics suggested garlic + garden pea intercropping system was the most remunerative with the highest net return and benefit-cost ratio (Rs. 1, 52,209.23, and 2.67), respectively.

Effects of foliar application of selenium and potassium-humate on oat growth in Baloza, North Sinai, Egypt

In this study, the effects of foliar application of selenium (Se) at different concentrations were examined based on changes in several parameters such as nitrogen, phosphorous, and potassium (NPK) concentration in soil and oat plant, oat yield, organic matter in the soil (OMS), non-enzymatic antioxidants, and total phenol content. Chromium (Cr), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) concentrations were also assessed in oat straw and seeds. The study complies with local and national guideline. Simultaneous application of potassium humate (K-humate) with Se was also investigated in this study. Se application increased the bioavailability of N and P in soil and their total concentration in the straw and seeds of each plant. Se concentrations were proportional to the amount of phosphorous found in soil (P-soil) but not with K concentrations in seed (K-plant). Application of K-humate with Se increased the bioavailable fraction of K-soil; however, it did not increase the bioavailable fraction of K-straw or K-seed. Although the application of Se alone substantially enhanced yield, the simultaneous application of K-humate showed no additional effect. Moreover, responses of seed yield and plant length were not significant after the application of Se with or without K-humate. OMS and total phenol content were proportional to the application rate of Se with and without K-humate. Non-enzymatic antioxidant content was also proportional to Se concentrations but not proportional to K-humate. The total Se concentrations in the soil, plant straw, and seeds increased with the addition of K-humate. Furthermore, the total Cr concentrations were reduced after the application of Se and K-humate. Fe concentration in the straw and seeds varied from one treatment to another, and Mn concentration was reduced in response to the foliar application of Se and K-humate. Zn concentrations in the straw and seeds of plants were reduced with the application of varying concentrations of Se. Increasing the application rate of Se induced a reduction in the Cu concentration in seeds. In contrast, the simultaneous application of Se and K-humate increased the Cu concentration in seeds.

Study on the relationship between functional characteristics and environmental factors in karst plant communities.

Environmental factors drive changes in plant functional traits, which in turn promote community recovery. The environmental conditions of the community are different at different recovery stages. Changing environmental factors may drive the changes in plant functional traits at the community level and affect species adaptation. We studied plant communities in five different recovery stages (herb, grass and shrub, shrub, tree and shrub, and tree) in the karst plateau of Zhenning, Guizhou (The vegetation in the study area has undergone a gradual natural recovery process after the forests were deforested in 1958–1960). We studied functional traits and their links to environmental factors. The main results include the following. (1) Over time, plant height, leaf dry matter content, leaf nitrogen content and leaf phosphorus content increased significantly in the tree stage, while leaf thickness and specific leaf area decreased significantly in the tree stage. (2) Soil organic carbon, soil N content, soil P content, soil C:P and soil C:K showed an increasing trend, and were significantly higher in tree stage than in other stages. Soil potassium content fluctuated and soil bulk density decreased gradually, reaching the lowest value in the tree stage, but the difference was not significant. (3) During the restoration process, the functional characteristics changed from a combination of plant communities with high specific leaf area and low dry matter content with a short plant height to plant communities with low specific leaf area and high dry matter content with a tall plant height. (4) As recovery proceeded, the study area gradually changed from a soil nutrient‐poor environment to a nutrient‐rich environment. Overall, the environmental factors vary greatly during the recovery of plant communities in karst areas. The plant community shifts from an aggressive (resource acquisition) to a conservative (environmental barrenness resistance) ecological strategy. The soil phosphorus content and soil C:K are the main environmental factors affecting the changes in functional traits during the restoration of karst plant communities in Zhenning.

Nutrient Status and Yield of French marigold as Influenced by Application of Spent Mushroom Compost, Biofertilizer and MKP Foliar Application

An experiment was carried out in open field condition during the year 2018-19 to ascertain the effect of spent mushroom compost, biofertilizers and MKP foliar application on nutrient status, yield and profitability of French marigold. The experiment was laid out in Completely Randomized Block Design (CRBD) and comprised of twenty three treatments replicated thrice. The highest available soil nitrogen content (259.95 Kg/ha), available soil P (33.23 Kg/ha) and available soil potassium content (244.60 Kg/ha) was recorded with Control (100% RDF).Maximum total leaf nitrogen (1.367%), leaf phosphorus (0.433%) and leaf potassium content (1.88%) was recorded with treatment 75% RDF + spent mushroom compost + biofertilizers + 1% foliar spray of MKP (T9) whereas, the lowest total leaf nitrogen content (1.103%), leaf phosphorus content (0.313%) and total leaf K (1.33 %) was recorded with no fertilizer application (Farmers practice). Plants treated with 75% RDF + Biofertilizers + 1% foliar spray of MKP (T8) recorded the highest benefit cost ratio (2.81:1) closely followed by benefit cost ratio of 2.54 in 100% RDF whereas lowest benefit cost ratio (0.36:1) was recorded in the treatment T17 comprising 25 % RDF + Spent mushroom compost (1 kg/m2).Highest chlorophyll content (48.89%) was recorded with T8.

Endophytic Klebsiella aerogenes HGG15 stimulates mulberry growth in hydro-fluctuation belt and the potential mechanisms as revealed by microbiome and metabolomics.

Growth promotion and stress tolerance induced by endophytes have been observed in various plants, but their effects on mulberry regularly suffering flood in the hydro-fluctuation belt are less understood. In the present study, endophytic Klebsiella aerogenes HGG15 was screened out from 28 plant growth promotion (PGP) bacteria as having superior PGP traits in vitro and in planta as well as biosafety for silkworms. K. aerogenes HGG15 could actively colonize into roots of mulberry and subsequently transferred to stems and leaves. The 16S ribosomal RNA (V3–V4 variable regions) amplicon sequencing revealed that exogenous application of K. aerogenes HGG15 altered the bacterial community structures of mulberry roots and stems. Moreover, the genus of Klebsiella was particularly enriched in inoculated mulberry roots and was positively correlated with mulberry development and soil potassium content. Untargeted metabolic profiles uncovered 201 differentially abundant metabolites (DEMs) between inoculated and control mulberry, with lipids and organo-heterocyclic compounds being particularly abundant DEMs. In addition, a high abundance of abiotic stress response factors and promotion growth stimulators such as glycerolipid, sphingolipid, indole, pyridine, and coumarin were observed in inoculated mulberry. Collectively, the knowledge gained from this study sheds light on potential strategies to enhance mulberry growth in hydro-fluctuation belt, and microbiome and metabolite analyses provide new insights into the growth promotion mechanisms used by plant-associated bacteria.

Morphological variability of Carex buekii (Cyperaceae) as a function of soil conditions: a case study of the Central European populations

Carex buekii is a highly adaptive species showing a fairly wide ecological spectrum. It belongs to the group of river corridor plants which are vulnerable to any human activity directed at transformation of river valley habitats worldwide. This study was aimed at: determining the phenotypic variability of the species in the central part of its range, examining effects of soil conditions on the sedge’s morphological traits, and finding out whether the phenotypic plasticity observed may have taxonomic implications. A total of 487 specimens from 26 populations were collected in Hungary, Poland and Slovakia and tested by univariate, bivariate, and multivariate statistical methods. The analysis involved 16 morphological traits and 7 soil parameters (organic matter, pH, potassium, phosphorus, nitrogen, magnesium, calcium). Soil conditions were shown to affect the C. buekii morphology; particularly important was potassium, the only soil parameter that was indicated as a factor affecting intra-specific variability. Sites with lower contents of bioavailable potassium hosted C. buekii individuals which were generally smaller than those at sites showing higher soil potassium contents. The relationship held true also with respect to generative traits important in sedge taxonomy, i.e. utricle and beak lengths. Consideration of morphological differences only, without analysing relationships between morphology and soil conditions, could have resulted in distinguishing new entities at the level of species, subspecies or variety. Thus, knowledge on the range of phenotypic plasticity in field populations seems to be of a key importance in taxonomic studies.

Characterization of Soil Quality Parameters under Plain and Hilly Region of East Siang District, Arunachal Pradesh

The investigation conducted at the laboratory of Rajiv Gandhi South Campus, Banaras Hindu University, Barkachha; Mirzapur during the year 2021. The objective of this study was to characterize the physicochemical properties under plain and hilly areas soil of East Siang District, Arunachal Pradesh. By using GPS camera, 30 soil samples under plain area and 30 soil samples under hilly area was collected. The physical and chemical properties of soil were critically analyzed. According to the soil nutrient index of the study area, the soils of east siang district found out to be low in the available Nitrogen content, Potassium, and sulphur content of soil and medium in organic carbon and phosphorus content of the soil of both plain and hilly region. The plain area soils were found acidic to neutral in reaction and free from salinity. The pH of hilly area soil was found acidic in reaction and free from salinity.

A study on soil fertility status of adopted model village in Rahuamani, Kahra block of Saharsa district in Bihar

Soil fertility assessment in a region is the most basic decision-making tool for sustainable soil nutrient management. A soil fertility status inventory work was carried out in adopted model village, Rahuamani of Kahra block in Saharsa district. One hundred soil samples were randomely collected based on the handled GPS location. Results showed that 91% samples were found in neutral reaction and all the samples fall under normal and safe category of electrical conductivity. Sixty-five per cent soil samples fall under lows organic carbon content and 35% samples were medium in organic carbon content. 61% of the study area was deficient in available N and 81% samples were fall under medium category of fertility status of P5O5. The available potassium content in soil, 90% of the soil samples were medium fertility level. It was found that 75% samples were in medium soil sulphur category. Zn content of the study are fall under the medium fertility category. Similarly, 58% sample deficient in copper content and 47% sample are deficient in available Mn. Out of total soil sample analyzed 78% samples are deficient in B content in soil.

Soil Conditioner Affects Tobacco Rhizosphere Soil Microecology.

Reasonable fertilization management can increase nutrient content and enzyme activity in rhizosphere soil, and even increase soil microbial richness. However, different fertilizers could raise distinct influences on the soil properties, including soil environmental factors (physicochemical properties and enzymatic activities) and microbial community. Here, the effects of two soil amendments (microbial fertilizer and woody peat) on environmental factors and microbial community structure in tobacco rhizosphere soil were evaluated, with the correlations between microbes and environmental factors explored. As the results, microbial fertilizer could effectively alleviate soil acidification, increase available potassium and organic matter contents in soil, and was also beneficial to increase nitrate reductase activity in rhizosphere soil. Fertilizers cause changes in the abundance of certain microbes in the soil. Besides, it was shown that the candidate phyla Gal15, Acidobacterota, Latescibacterota, Mortierellommycota, Basidiomycota, and Rozellomycota in tobacco rhizosphere soil had significant correlation with soil environmental factors. Through the functional analysis of these populations, it can be deduced that the changes in the abundance of certain microorganisms may be an important reason for the differences in environmental factors. All these indicated that the differences of environmental factors in different treatments are closely related to the abundance of some special soil microorganisms. Studying the life activities of these microbes would provide good guidance for exploring the interaction among crops, soil, and microorganisms and improving crop yields.

Estimation of Fertility Status of Coastal Soils for Agricultural Planning in Bangladesh

A study was conducted to know the fertility status of coastal soils of Bangladesh for agricultural planning. Thirty composite soil samples were collected from different locations of Kalapara upazila under Patuakhali coastal district in Bangladesh with Geographic Positioning System (GPS) positions. The soil samples were analyzed for physical properties (moisture, texture, bulk density, particle density and porosity) and chemical properties (pH, electrical conductivity, total nitrogen, organic carbon, exchangeable sodium, exchangeable potassium, available sulphur and available phosphorus). The range of moisture contents of collected soils was 24 to 29% and the textural class was silty clay. The bulk density ranged from 1.30 to 1.47 gcm-3. The particle density ranged from 2.31 to 2.49 gcm-3. The porosity of soil samples ranging from 40.96 to 46.06%. The pH ranged from 5.85 to 6.45. The EC value of collected soils ranged from 3.10 to 5.12 dSm-1. The total nitrogen and organic carbon content was low to medium. The exchangeable sodium and potassium content of soils ranged from 9.22 to 18.47 meq 100g-1 and 0.16 to 0.27 meq 100g-1, respectively. The available sulphur and phosphorus content of soils ranged from 17.21 to 33.21 mg kg-1 and 17.12 to 33.09 mg kg-1, respectively. The results revealed that the soils of the study area were slightly to moderately saline and thus the nutrients present in the soils were low to medium level. Hence, salinity problem of soils should be considered before agricultural planning in the study area.

Biochemical composition and function of subalpine shrubland and meadow soil microbiomes in the Qilian Mountains, Qinghai-Tibetan plateau, China.

Microorganisms participate in the soil biogeochemical cycle. Therefore, investigating variations in microbial biomass, composition, and functions can provide a reference for improving soil ecological quality due to the sensitivity of microorganisms to vegetation coverage changes. However, the differences in soil microorganisms between shrubland and meadow have not been investigated in ecologically vulnerable subalpine areas. This study aimed to investigate the biochemical composition and functions of the soil microbial community under two shrublands and a meadow at high altitudes (3,400–3,550 m). Three sites under two shrublands, Rhododendron thymifolium (RHO) and Potentilla fruticosa (POT), and one meadow dominated by Kobresia myosuroides (MEA), were selected on the southern slope of the Qilian Mountains on the northeastern edge of the Qinghai–Tibetan Plateau, China. Soil physicochemical properties, the microbial community composition expressed by the phospholipid fatty acid (PLFA) biomarker, and enzyme activities were analyzed as well as their relationships. The results showed that water holding capacity and the soil carbon, nitrogen, and potassium content in RHO and POT were higher than those in the MEA. Moreover, the soil active carbon, dissolved organic carbon, total nitrogen, and dissolved total nitrogen content in RHO were higher than those in POT. The abundance of total PLFAs, bacteria, and fungi beneath the shrublands was considerably higher than that in the MEA. The PLFA abundance in RHO was significantly higher than that in POT. The fungal-to-bacterial ratio of RHO and POT was significantly higher than that in the MEA. The activities of β-glucosidase, cellobiohydrolase, and leucine aminopeptidase were the highest in RHO among the three vegetation types, followed by POT and MEA. The redundancy analysis indicated that the biochemical composition of the soil microorganisms and enzyme activities were driven by total nitrogen, dissolved organic carbon, water holding capacity, and soil organic carbon. Therefore, shrublands, which have higher biomass, can improve soil moisture status, increase soil carbon and nitrogen content (especially active carbon and active nitrogen), and further increase the abundance of total PLFAs, bacteria, and fungi. The increase of microbial biomass indirectly enhances the activity of relevant soil enzymes. The variations in PLFA abundance and enzyme activities can be attributed to shrub species, especially evergreen shrubs, which create more favorable conditions for soil microorganisms. This study provides a theoretical basis for investigating the soil biogeochemical cycle and a scientific basis for soil management and vegetation restoration in the subalpine regions.

Chronological changes in soil biogeochemical properties of the glacier foreland of Midtre Lovénbreen, Svalbard, attributed to soil-forming factors

Glacier forelands provide an excellent opportunity to investigate vegetation succession and soil development along the chronosequence; however, there are few studies on soil biogeochemical changes from environmental factors, aside from time. This study aimed to investigate soil development and biogeochemical changes in the glacier foreland of Midtre Lovénbreen, Svalbard, by considering various factors, including time. Eighteen vegetation and soil variables were measured at 38 different sampling sites of varying soil age, depth, and glacio-fluvial activity. Soil organic matter (SOM) was quantitatively measured, and the compositional changes in SOM were determined following size-density fractionation. In the topsoil, the soil organic carbon (SOC) and total nitrogen (N) content was found to increase along the soil chronosequence and were highly correlated with vegetation-associated variables. These findings suggest that plant-derived material was the main driver of the light fraction of SOM accumulation in the topsoil. The heavy fractions of SOM were composed of microbially transformed organic compounds, eventually contributing to SOM stabilization within short 90-yr deglaciation under harsh climatic conditions. In addition to time, the soil vertical profiles showed that other environmental parameters, also affected the soil biogeochemical properties. The high total phosphorous (P) content and electrical conductivity in the topsoil were attributed to unweathered subglacial materials and a considerable amount of inorganic ions from subglacial meltwater. The high P and magnesium content in the subsoil were attributed to parent materials, while the high sodium and potassium content in the surface soil were a result of sea-salt deposition. Glacio-fluvial runoff hampered ecosystem development by inhibiting vegetation development and SOM accumulation. This study emphasizes the importance of considering various soil-forming factors, including parent/subglacial materials, aeolian deposition, and glacio-fluvial runoff, as well as soil age, to obtain a comprehensive understanding of the ecosystem development in glacier forelands.

Comparative Analysis of the Effects of Plastic Mulch Films on Soil Nutrient, Yields and Soil Microbiome in Three Vegetable Fields

Plastic film mulching is a common practice to increase vegetable yields. However, the effects of plastic mulch films on different vegetable fields remain largely unknown. In the current study, biodegradable mulch films (BDMs) and polyethylene mulch films (PEMs) were used to explore their effects on three vegetable fields (broccoli, chili pepper and garlic). Compared with bare soil, both BDMs and PEMs could effectively maintain higher exchangeable potassium contents in rhizosphere soil, and significantly increase various soil properties and microbial abundance both in rhizosphere and non-rhizosphere soils. In terms of yields, the treatments of BDMs and PEMs effectively increased broccoli, chili pepper and garlic yields by 17.6–19.0%, 21.3–23.3% and 26.0–29.5%, respectively, when compared with the bare soil. Our initial characterization provided insights into the effects of BMDs and PEMs on soil properties, yields and diversity of rhizosphere and non-rhizosphere microbial communities in three vegetable fields.

Assessment of Grassland Ecosystem Services and Analysis on Its Driving Factors: A Case Study in Hulunbuir Grassland

Grassland is the largest terrestrial ecosystem in China, and its ecological environment is currently facing several challenges. The service assessment of scientific and effective grassland ecosystem and in-depth analysis of its change mechanism is of great significance to clarify its protection demand and spatial optimization layout. This study used a set of quantitative surrogate biophysical indicators to evaluate the capability of grassland ecosystem services (i.e., carbon fixation, soil protection, water purification and provision, and biodiversity conservation) in the Hulunbuir grassland from 2000 to 2015 and use econometric models to explore their dynamic change mechanism. The results showed that from 2009 to 2012, the grassland ecosystem service value significantly declined, and from 2013 to 2015, its value significantly improved, but the overall level was still lower than that of 2000. The factor that has the highest degree of impact on grassland ecosystem services is the soil potassium content, and there is a significant positive correlation. This is mainly due to the important role of potassium in the photosynthesis of grassland plants; the least influential factors are social economic factors such as population and gross domestic product (GDP). It shows that the sparsely populated grassland ecosystem is not sensitive to these factors. In addition, climate, topography, and grassland management policies all have a significant impact on grassland ecosystem services. Against the backdrop of intensified pressure on ecological grassland protection and surging market demand for livestock products based on grassland resource input, the sustainable development of grassland areas needs to improve the supply capacity of grassland while ensuring its ecological security, so as to realize a win-win situation for its ecological and production functions.

Functional structure of plant communities along salinity gradients in Iranian salt marshes.

Salt marshes are unique habitats between sea or saline lakes and land that need to be conserved from the effects of global change. Understanding the variation in functional structure of plant community along environmental gradients is critical to predict the response of plant communities to ongoing environmental changes. We evaluated the changes in the functional structure of halophytic communities along soil gradients including salinity, in Iranian salt marshes; Lake Urmia, Lake Meyghan, Musa estuary, and Nayband Bay (Iran). We established 48 plots from 16 sites in four salt marshes and sampled 10 leaves per species to measure leaf functional traits. Five soil samples were sampled from each plot and 30 variables were analyzed. We examined the changes in the functional structure of plant communities (i.e., functional diversity [FD] and community weighted mean [CWM]) along local soil gradients using linear mixed effect models. Our results showed that FD and CWM of leaf thickness tended to increase with salinity, while those indices related to leaf shape decreased following soil potassium content. Our results suggest that the variations in functional structure of plant communities along local soil gradients reveal the effect of different ecological processes (e.g., niche differentiation related to the habitat heterogeneity) that drive the assembly of halophytic plant communities in SW Asian salt marshes.

Relationships between Soil Electrical Conductivity and Sentinel-2-Derived NDVI with pH and Content of Selected Nutrients

Site-specific crop management demands maps which present the content of the main macronutrients. Such maps are prepared based on optimized soil sampling within management zones, which should be quite homogenous according to nutrient content, especially the content of potassium and phosphorus. Delineation of management zones is very often conducted using soil apparent electrical conductivity (EC) or other variables related to soil condition, including satellite-derived vegetation indices. In this study conducted in North-Western Poland, relationships between soil electrical conductivity and the satellite-derived normalized difference vegetation index (NDVI) of various crops (wheat, barley, and rapeseed) with soil pH and content of P, K, and Mg were evaluated. Strong relationships were observed between NDVI of cereals with potassium content in soil. Correlation coefficients for wheat ranged from 0.37 to 0.60 for average potassium content for three years and from 0.05 to 0.63 for barley. Stronger relationships were observed for the years 2018 and 2019 when NDVI was based on Sentinel-2 data, while weaker for year 2017 when Landsat 8 NDVI was used. Relationships between EC and macronutrients content were similar to those observed with NDVI. Satellite-derived NDVI of cereals can be used as a variable for the delineation of within-field management zones. The same relationships were much weaker and not consistent for winter rapeseed.