Soil Potassium Content Research Articles

Influence of Different Sources and Levels of Phosphorus on Nutrient Use Efficiency (NUE) and Properties of Low Calcareous Soil

A field experiment was conducted during kharif season of 2023 at Post Graduate Instructional Farm, College of Agriculture, Pune to study the impact of different phosphorus sources and levels on soybean growth and nutrient uptake in low calcareous soil. The experiment was laid out in randomized block design having eight treatments with three replications. The treatments comprised T1 - Absolute control, T2 - RDF (50:75:45 kg ha-1 N: P2O5: K2O), T3 - 50% P2O5 through PROM, T4 - 75% P2O5 through PROM, T5 - 100% P2O5 through PROM, T6 - 100% P2O5 through DAP + FYM @12.5 t ha-1, T7 - 100% P2O5 through SSP + FYM @12.5 t ha-1 and T8 - 100% P2O5 through vermicompost. The soil of experimental site was clay loam in texture. The findings of the present investigation revealed that the higher nutrient use efficiency was registered in treatment 100% P2O5 through SSP + FYM @12.5 t ha-1 (16.25 kg kg-1). The application of 100% P2O5 through PROM recorded higher nutrient use efficiency (13.31 kg kg-1) over RDF (11.52 kg kg-1). In respect of agronomic nutrient use efficiency, 100% P2O5 through SSP + FYM @12.5 t ha-1 registered higher nitrogen (40 kg grain kg nutrient-1), phosphorus (26 kg grain kg nutrient-1) and potassium efficiency (44 kg grain kg nutrient-1) to soybean crop. The agronomic efficiency of nitrogen, phosphorus and potassium was observed higher in treatment 100% P2O5 through PROM over treatment RDF. After harvest of crop the soil pH was remained unaffected while the electrical conductivity of soil was significantly higher in 100 % P2O5 through vermicompost and PROM to soybean crop. The application of 100% P2O5 either through vermicompost or PROM recorded at par organic carbon content in soil (0.66% and 0.64% respectively). The application of 100% P2O5 through PROM significantly reduced calcium carbonate (6.29%) in soil. The 100% P2O5 through SSP + FYM @12.5 t ha-1 showed higher available nitrogen in soil (297.33 kg ha-1) while the application of 100% P2O5 through DAP + FYM @12.5 t ha-1 exhibited higher level of available phosphorus and potassium content in soil (41.33 and 745.33 kg ha-1, respectively). Further, the application of 100% P2O5 through vermicompost was also significantly superior in available micronutrients like iron (5.7 mg kg-1), manganese (9.9 mg kg-1), zinc (4.6 mg kg-1) and copper (10.4 mg kg-1). The application of 100% P2O5 through PROM registered significantly higher available nitrogen (287.33 kg ha-1), available phosphorus (37.33 kg ha-1), available potassium (737.67 kg ha-1), available micronutrients viz. iron (5.4 mg kg-1), manganese (9.2 mg kg-1), zinc (4.4 mg kg-1) and copper (10.4 mg kg-1) over recommended dose of fertilizers. In general, the integration of organic fertilizers, FYM, PROM and vermicompost, with chemical fertilizers can significantly enhance nutrient use efficiency, soil nutrient content, improve soil health and increase soybean yield in low calcareous soils.

Biofertilizers: A sustainable strategy for enhancing physical, chemical, and biological properties of soil

A biofertilizer is a biologically derived substance that can enhance soil fertility. It is beneficial for enhancing soil fertility by introducing microorganisms that produce organic nutrients and perhaps decreasing plant illnesses. An extensive review was done to examine the efficacy of several biofertilizers in improving soil properties, including their physical, chemical, and biological characteristics. The secondary data and material for the article were gathered from a variety of sources, including government reports, published research papers, reports from various organizations, and pertinent websites that were examined and their conclusions presented. Although biofertilizers have proven to be a very sustainable method for improving soil quality and increasing crop output, there is a lack of extensive research on their effects on soil’s physical, chemical, and biological aspects. This study aims to offer a comprehensive understanding of various biofertilizers and their effects. This investigation indicated that biofertilizers such as Nitrogen-fixing bacteria, phosphate solubilizers, and potassium solubilizers help to increase NPK content in the soil leading to an increase in the productivity of soil. Moreover, biofertilizers help to enhance soil physical properties (soil bulk density, soil moisture, soil temperature, and soil color), chemical properties (soil pH, soil nitrogen content, soil phosphorus content, soil potassium content, and soil organic carbon content), and chemical properties (population of bacteria, fungi, and actinomycetes). Overall, by overcoming the challenges with biofertilizers in agriculture, we can attain agricultural sustainability.

Ecological Capacity and Bioenergy Potential of Agrocenoses as a Way of Sustainable Agriculture

Background: Calculation of bioenergy potential and ecological capacity are promising methods for assessing the state of an agro-landscape, allowing us to promptly respond to changes in its sustainability. The article presents the results of soil research and calculation of bioenergy potential of the farm territory in the zone of dry steppe on chestnut soils. Methods: Assessment of anthropogenic load on agricultural landscape is based on ecological standards and point system of relative fertility. The determination of the ecological capacity by BEPT of an agrocenosis occupied by winter wheat and sunflower was carried out according to the method of V.M. Volodin, R.F. Eremina, N.F. Mikhailova. Determination of erosion and geomorphological characteristics of the research object was carried out using geoinformation technologies. The basis for creation of digital elevation model (DEM) is the data of radar survey of the Earth surface (SRTM4). Result: Soils of the research object have low and average humus content. Nitrogen level in the soil varies from very low to good; nitrogen availability in the fields is average. Provision with mobile phosphorus is average. Soil potassium content is mostly high. As a result of calculations, it was found that in the conditions of the dry steppe zone, the bioenergy potential of the agrolandscape area occupied by winter wheat is 2735.72 GJ/ha, sunflower-2647.4 GJ/ha. At the same time, the ecological capacity of the field occupied by winter wheat is 2764.6 GJ/ha and sunflower-2676.8 GJ/h.

Influence of composted manures and co-composted biochar on growth performance of saffron and soil nutrients under varying electrical conductivity soil conditions: A two-year field study

The stigmas of saffron (Crocus sativus L.) are known as “red gold” for being the most expensive spice of the world. This medicinal crop grows well in the regions with cold winter Mediterranean climate. However, salinity can be one of the limiting factors for its cultivation in these regions. Composted manures and their co-compost with wood-derived biochar as fertilizers in saline soil can reduce the salinity stress on saffron. In this study, the composted manures from dairy farms (FYM), sheep and goats (SG) and poultry (PM) and their co-compost with wood-derived biochar (FYM-B, SG-B and PM-B) were amended in non-saline (EC1:2 0.25 dS m−1, SOM; 9.9 g kg−1) and soil with natural slight salinity (EC1:2; 1.95 dS m−1, SOM; 30.9 g kg−1) soil for two consecutive years with the total amendment rate of 65 t ha−1 for each fertilizer. The saline soil was transported from an agricultural farm (30 km away from research field); whereas, the non-saline soil was not transported and was not cultivated before. The amendment of fertilizers and sowing of corms were conducted at the same time in the mid of August. The stigma yield in saline control soil was significantly lower than non-saline control in both cropping years. In non-saline soil, all fertilizers reduced stigma yield of first-year crop by 14–60 % (P < 0.05). No differences between treatments for the stigma yield of second year crop in non-saline and of first year crop in saline soil were observed. In saline soil, FYM and PM fertilizers increased stigma yield of second year crop by 44 % and 41 %, respectively (P < 0.05). The two-year cumulative agronomic efficiencies for nitrogen and phosphorus and the nitrogen use efficiency for leaf biomass were lower under fertilizer treatments than control in non-saline and saline soil. In non-saline soil the PM-B; whereas, in saline soil all fertilizers (except SG) increased the phosphorus use efficiency of leaves (P < 0.05). The two-year amendment of composted manures and FYM-B in non-saline soil resulted in high uptake of sodium in leaves (P < 0.05); whereas, such effect was not observed for saline soil. Almost all fertilizers increased ∼2–5 fold the concentration of bioavailable phosphorus and ∼2–3 fold the concentration of potassium in non-saline and saline soil (P < 0.05). The positive influence of fertilizers on stigma yield and PUE of leaves of second year crop was observed only for saline soil. Furthermore, contrary to the results for non-saline soil, these fertilizers did not cause an increased uptake of Na in leaves in saline soil. We attribute this effect to the high concentration of SOM and gradual decline in EC (0.94–1.71 dS m−1) over time in saline soil. The gradual improvement in yield (from negative to neutral in non-saline and from neutral to positive in saline soil) was observed over time. Amendment of fertilizers and sowing of corms at same time may be the reason for their negative influence on stigma yield in low SOM-containing non-saline soil.

The analysis of release and percolation rate of nutrients from regular and obsidian-based slow-release fertilizers.

Research on the observation of nutrient release rates from slow-release and regular fertilizers combined with the percolation rate in the soil is scarce. This work aims to observe potassium and phosphate release behavior from slow-release and regular fertilizer, followed by the percolation of that nutrient in the soil. The characteristics of the soil were analyzed using X-ray Diffraction (XRD), X-ray Fluorescence (XRF), and Scanning Electron Microscope (SEM). The concentration of potassium and phosphate in soil is analyzed using Atomic Absorption Spectroscopy (AAS) and Ultraviolet-Visible Spectroscopy (UV-Vis), respectively. The release rate of nutrients from slow-release fertilizer is 6 to 8 times slower than regular fertilizer. Meanwhile, the rate of nutrients released from slow-release and regular fertilizer followed by soil percolation matches the quadratic equation. Potassium adsorption on the soil surface is significantly higher than that of potassium. The negativity of soil polarity contributed to the high level of potassium adsorption on soil particle surfaces. The low phosphate adsorption capability of magnetite and the negativity of soil polarity contributed to the soil's low phosphate adsorption.

Quantitative analysis of soil potassium by near-infrared (NIR) spectroscopy combined with a three-step progressive hybrid variable selection strategy

Soil potassium is a crucial nutrient element necessary for crop growth, and its efficient measurement has become essential for developing rational fertilization plans and optimizing crop growth benefits. At present, data mining technology based on near-infrared (NIR) spectroscopy analysis has proven to be a powerful tool for real-time monitoring of soil potassium content. However, as technology and instruments improve, the curse of the dimensionality problem also increases accordingly. Therefore, it is urgent to develop efficient variable selection methods suitable for NIR spectroscopy analysis techniques. In this study, we proposed a three-step progressive hybrid variable selection strategy, which fully leveraged the respective strengths of several high-performance variable selection methods. By sequentially equipping synergy interval partial least squares (SiPLS), the random forest variable importance measurement (RF(VIM)), and the improved mean impact value algorithm (IMIV) into a fusion framework, a soil important potassium variable selection method was proposed, termed as SiPLS-RF(VIM)-IMIV. Finally, the optimized variables were fitted into a partial least squares (PLS) model. Experimental results demonstrated that the PLS model embedded with the hybrid strategy effectively improved the prediction performance while reducing the model complexity. The RMSET and RT on the test set were 0.01181% and 0.88246, respectively, better than the RMSET and RT of the full spectrum PLS, SiPLS, and SiPLS-RF(VIM) methods. This study demonstrated that the hybrid strategy established based on the combination of NIR spectroscopy data and the SiPLS-RF(VIM)-IMIV method could quantitatively analyze soil potassium content levels and potentially solve other issues of data-driven soil dynamic monitoring.

Multiple cropping effectively increases soil bacterial diversity, community abundance and soil fertility of paddy fields

BackgroundCrop diversification is considered as an imperative approach for synchronizing the plant nutrient demands and soil nutrient availability. Taking two or more crops from the same field in one year is considered as multiple cropping. It improves the diversity and abundance of soil microbes, thereby improving the growth and yield of crops. Therefore, the present study was conducted to explore the effects of different multiple winter cropping on soil microbial communities in paddy fields. In this study, eight rice cropping patterns from two multiple cropping systems with three different winter crops, including Chinese milk vetch (CMV), rape, and wheat were selected. The effects of different multiple winter cropping on soil microbial abundance, community structure, and diversity in paddy fields were studied by 16 S rRNA high-throughput sequencing and real-time fluorescence quantitative polymerase chain reaction (PCR).ResultsThe results showed that different multiple winter cropping increased the operational taxonomic units (OTUs), species richness, and community richness index of the bacterial community in 0 ~ 20 cm soil layer. Moreover, soil physical and chemical properties of different multiple cropping patterns also affected the diversity and abundance of microbial bacterial communities. The multiple cropping increased soil potassium and nitrogen content, which significantly affected the diversity and abundance of bacterial communities, and it also increased the overall paddy yield. Moreover, different winter cropping changed the population distribution of microorganisms, and Proteobacteria, Acidobacteria, Nitrospira, and Chloroflexi were identified as the most dominant groups. Multiple winter cropping, especially rape-early rice-late rice (TR) andChinese milk vetch- early rice-late rice (TC) enhanced the abundance of Proteobacteria, Acidobacteria, and Actinobacteria and decreased the relative abundance of Verrucomicrobia and Euryarchaeota.ConclusionIn conclusion, winter cropping of Chinese milk vetch and rape were beneficial to improve the soil fertility, bacteria diversity, abundance and rice yield.

Annual Flood Phenomenon and Fertility Status of Rice Soil in The Coastal Area of Bengkulu

[ANNUAL FLOOD PHENOMENON AND FERTILITY STATUS OF RICE SOIL IN THE COASTAL AREA OF BENGKULU]. The rice fields in Rawa Makmur Village were agricultural land that was affected by annual floods. Soil fertility status is important for increasing the productivity of paddy. The research aimed to get the fertility status of soil affected by annual flood disasters, evaluating and mapping the distribution of soil fertility status at the research location. The methods used in this research include survey and soil testing methods at the Soil Science Laboratory, Faculty of Agriculture, Bengkulu University. Further evaluation of soil fertility status is in accordance with technical instructions from the Soil Research Center, Bogor (1995). This research was conducted in June – August 2023. The soil CEC value from each sampling point was classified as high with values ranging from 28.15 me/100 g - 39.83 me/100 g. The base saturation value in the study was classified as very low to moderate with values ranging from 11.49% - 40.08%. Soil organic C at the research location from each sampling point was classified as moderate to very high with values ranging from 2.42% - 5.97%. The soil phosphorus content at the research locations observed was classified as very low to low with values ranging from 2.69 mg/100 g – 12.11 mg/100 g. The soil potassium content at each sample point at the research location observed was classified as very low with values ranging from 0.14 mg/100 g – 1.43 mg/100 g. The research results show that the flood phenomenon has a significant impact on soil fertility. The soil fertility status at the research location is classified as low. Soil fertility parameters which are limiting factors in the status of soil fertility in Rawa Makmur Village are phosphorus, potassium and pH. So it is necessary to add P and K fertilizer to improve the soil fertility status.

Effects of Substrate Composition on the Growth Traits of Grafted Seedling in Macadamia (Macadamia integrifolia) Nuts.

Macadamia nut plantings in China are expanding year by year. In order to breed and promote superior varieties, this study analyzed the effects of different rootstocks and scions on the survival rate of grafted seedlings, and then selected the best substrate composition for plant growth. The results showed that the survival rate of the HAES788 variety as rootstock and Guire No. 1 as scion was the highest, reaching 96%. The optimal grafting time in December was better than that in March. Furthermore, among 16 substrate formulations, T12, T13, T15, and T16 had advantages of agglomerated soil and more well-developed root systems compared to the CK made of loess. The plant height, stem diameter, leaf length, leaf width, and dry weight of the aboveground and underground parts of the grafted seedlings planted in these substrate formulations were significantly higher than those plants planted in the CK. In addition, the substrate formulations T12, T13, T15, and T16 significantly improved the organic matter, total nitrogen, and total potassium content of the substrate soils, but little improvement was observed for total phosphorus content after 13 months. Overall, macadamia grafting times are best in December, with HAES788 and Guire No. 1 being the best rootstock and scion. The optimal substrate formulations are T12, T13, T15, and T16. This study provides a solid foundation for the production of high-quality macadamia plants.

Effects of different microbial agent applications on the growth and quality of saffron (Crocus sativus L.) cormels

Saffron (Crocus sativus L.) is a bulbous flower whose dried stigmas are used as a herbal medicine and as a spice. Saffron is cultivated worldwide, but corm degradation is an important factor affecting its yield and quantity. This study investigated the effects of three different microbial agents (Bacillus megaterium, Brevibacillus laterosporus, Paenibacillus mucilaginosus) on the growth and quality of saffron cormels. Both the weight and circumference of the cormels were significantly increased in response to microbial agent treatment. Measurements of the physiological and biochemical characteristics of the cormels as well as the flowering traits showed that the starch and protein contents as well as the flowering rate and stigma yield increased significantly after the application of the three microbial agents. Analyses of soil physicochemical properties and microbial populations revealed increases in the soil potassium content and a significant alteration in the soil microbial community structure in response to treatment. Our results showed that the application of three microbial agents enhances the growth, nutritional status and health of saffron cormels and improves the soil environment during saffron corm cultivation. Paenibacillus mucilaginosus also increased the accumulation of crocins and picrocrocin in stigmas. Our results provide the theoretical and practical knowledge needed to reduce corm degradation and to improve saffron corm cultivation.

Assessment of Physico-chemical Properties of Soil from Various Regions of Different Taluk of Pathanamthitta District in the State of Kerala, India

The assessment of Physico-Chemical Properties of Soil from Various Regions of Different Taluk of Pathanamthitta District of Kerala in 2023-24 was a valuable endeavour. A total of 27 samples were collected at profile depths of 0-15, 15-30, and 30-45. It is interesting to note the variations in soil colour between dry and wet conditions, ranging from light brown to dark reddish brown.The soil textural class was identified as Sandy clay Loam, and the sand, silt and clay percentage varied from 45.18% to 50.64%, 17.21% to 20.70%, 30.91% to 34.61%. Bulk Density was varied from 1.08 Mg m-3 to 1.28 Mg m-3. The Particle Density varied from 2.02 Mg m-3 to 2.55 Mg m-3. The Pore Space (%) ranged from 40.18% to 50.62%. The Water Retaining Capacity (%) ranged from 39.19 to 48.98%. The pH value ranged from 4.9 to 6.9. The Electrical Conductivity ranged from 0.03 to 0.30 dS m-1. The value of total Organic Carbon (%) varied from 0.16 to 1.68 %. The available Nitrogen content of soil ranged from 119.45 to 286.07 kg ha-1. The available Phosphorus content of soil ranged from 13.23 to 64.20 kg ha-1. Available Potassium content of soil ranged from 100.80 to 382.40 kg ha-1. Exchangeable Calcium content of soil ranged from 1.7(meq 100g-1) to 9.1(meq 100g-1). Exchangeable Magnesium content of soil ranged from 0.23 (meq 100g-1) to 0.74(meq 100g-1). The Sulphur content of soil ranged from 0.03 to 0.44 kg ha-1. The findings revealed minor increases in bulk and particle density with depth, yet the overall physical condition of the soil seems favourable for plant growth. It is evident that the soils are slightly acidic but meet the acceptable EC limit. The high levels of Organic Carbon are promising, while Nitrogen is lower and Phosphorus and Potassium levels are moderate to high. However, secondary nutrients like Calcium, Magnesium, and Sulphur are relatively low. Nutrient levels appear to be influenced by soil depth, with leaching due to higher precipitation levels in the area contributing to nutrient deficiencies. The results suggest that improvements can be made by implementing strategies such as cover crops, green manure, legume cultivation, mulching, and specific cropping systems to address leaching concerns.

Metagenomic evaluation of peanut rhizosphere microbiome from the farms of Saurashtra regions of Gujarat, India

The narrow zone of soil around the plant roots with maximum microbial activity termed as rhizosphere. Rhizospheric bacteria promote the plant growth directly or indirectly by providing the nutrients and producing antimicrobial compounds. In this study, the rhizospheric microbiota of peanut plants was characterized from different farms using an Illumina-based partial 16S rRNA gene sequencing to evaluate microbial diversity and identify the core microbiome through culture-independent (CI) approach. Further, all rhizospheric bacteria that could grow on various nutrient media were identified, and the diversity of those microbes through culture-dependent method (CD) was then directly compared with their CI counterparts. The microbial population profiles showed a significant correlation with organic carbon and concentration of phosphate, manganese, and potassium in the rhizospheric soil. Genera like Sphingomicrobium, Actinoplanes, Aureimonas _A, Chryseobacterium, members from Sphingomonadaceae, Burkholderiaceae, Pseudomonadaceae, Enterobacteriaceae family, and Bacilli class were found in the core microbiome of peanut plants. As expected, the current study demonstrated more bacterial diversity in the CI method. However, a higher number of sequence variants were exclusively present in the CD approach compared to the number of sequence variants shared between both approaches. These CD-exclusive variants belonged to organisms that are more typically found in soil. Overall, this study portrayed the changes in the rhizospheric microbiota of peanuts in different rhizospheric soil and environmental conditions and gave an idea about core microbiome of peanut plant and comparative bacterial diversity identified through both approaches.

Reuse of Sewage Sludge as Organic Agricultural Products: An Efficient Technology-Based Initiative

Rapid urbanisation has led to a dramatic increase in sewage sludge production. There are limited methods of managing sewage sludge along with high energy and monetary investment. A cost-effective, environment-friendly, and sustainable solution needs to be developed for the management of sewage sludge. In the current study, sludge from the Jagjeetpur sewage treatment plant (STP) had been collected, composted, and characterized during January and February 2022. A comparison of STP sludge compost and compost made from farmyard manure showed the presence of essential agricultural nutrients in them, due to which they find application for plant growth. Two products, Jaivik Poshak and Jaivik Prom, containing farmyard compost, were compared with the amended version of the same, containing compost from STP sludge instead of normal compost. The results showed that the modified Jaivik Poshak was the best for maintaining pH and increasing electrical conductivity. The available nitrogen in the soil upon its application increased by 1.6 times (p&lt;0.001) with respect to control, and it brought about 100% tomato seed germination within sixteen days. The above finding has been validated by goodness of fit value, factor analysis, and hierarchical analysis. The product, modified Jaivik Prom increased organic carbon content and brought about 5.81 and 8 times the enhancement in available phosphorous (p&lt;0.001) and potassium (p&lt;0.001) content in soil, respectively, with respect to the control set. The heavy metal content in the soil as a result of all types of treatment was within the permissible limit. This study thus proves that sludge from STP may be used for agricultural uses after proper fortification and testing to convert waste to wealth along with environmental sustenance.

Fertilization enhances rice productivity by promoting phosphorus uptake and altering soil microbiota

Fertilization can enhance crop yield and improve soil health. However, its effects on nutrient uptake, soil microbiota, and rice yield remain unclear. Herein, we designed a double-cropping system with different fertilization treatments to determine their contributions to paddy soil agroecosystem and rice yield. Soil samples were collected before planting the early rice, after harvesting early rice, and after harvesting the late rice. Soil physicochemical properties, and rice yield, and rice nutrient (total nitrogen, phosphorus, and potassium contents) were determined. Variation of soil microbiota were also determined by high-throughput sequencing. We found that soil potassium content significantly improved during the planting process (P < 0.05), while rice phosphorus displayed significant variation under fertilization (P < 0.05). Notably, late rice yield was significantly higher than early rice yield (P < 0.001) after fertilization treatment. Furthermore, rice yield was positively correlated with available soil phosphorus (P < 0.05), indicating that fertilization promoted phosphorus uptake. Organic fertilizer altered the soil microbiota and increased Chloroflexi phyla abundance, while organic fertilizer combined with a compound microbial agent increased the diversity of soil microbial communities. A partial least squares path model revealed that fertilizer treatment directly positively affected rice yield by influencing phosphorus uptake and Shannon index (P < 0.01). Collectively, this study demonstrates that organic fertilization with compound microbial agents can stabilize soil nutrients, increase soil microbial diversity, and improve rice yield, thereby offering a guide for enhancing fertilizer utilization and improving agroecosystems.

Effects of Various Potassium Fertilizer Dosages on Agronomic and Economic Assessment of Sweet Potato Fields

To explore the effects of various potassium fertilizer dosages on sweet potatoes, field experiments were conducted in 2018 and 2019 using a randomized block design. In the experiment, the control (completely blank, no fertilizer), KS0 (potassium blank, no potassium fertilizer), KS100 (100 kg K2O ha−1), KS200 (200 K2O ha−1), and KS300 (300 K2O ha−1) treatments were set up. The application of potassium fertilizer increased the potassium content of sweet potato plants, thereby increasing the chlorophyll content, net photosynthetic rate, and the fluorescence chlorophyll parameters. It also increased the amylose content in tuber roots to increase the total starch content and yield of sweet potatoes. Specifically, the KS200 treatment significantly improved the soil potassium content, potassium absorption, potassium agronomic efficiency, and potassium recovery efficiency. Compared with the other treatments, the yield and net profit of the KS200 treatment increased by 0.89–27.05% and 2.34–30%, respectively, on average, over two years. Based on factors such as sweet potato yield and starch content, the recommended amount of potassium fertilizer was 200 kg ha−1, which has significant economic benefits and theoretical value.

A novel deep learning model to predict the soil nutrient levels (N, P, and K) in cabbage cultivation

Cabbage (Brassica oleracea) is a green cruciferous vegetable. Major nutrients (nitrogen, phosphorus, and potassium) are frequently applied to the soil due to low fertility levels. However, optimizing required fertilizer levels are extremely important to avoid any overuse and underuse. Therefore, it is important to develop a comprehensive methodology for evaluating the major nutrients in the soil. In this research, a deep learning model was introduced to predict the nitrogen, phosphorus, and potassium content of the soil by analyzing the growing characteristics of the plants, such as plant height, the number of leaves, and the average leaf area of the plant. To achieve this, the growing characteristics of the cabbage plants were recorded weekly along with the respective soil nitrogen, phosphorus, and potassium content of the nearby soil. After the data was trained using the Levenberg–Marquardt algorithm and tested with different transfer functions such as logarithmic sigmoid, pure linear, and tangent sigmoid, better predictions were obtained through the model. According to the Pearson correlation values, pure linear and tangent sigmoid showed higher values, ranging from 0.99 for training, testing, validation, and all data points from the model, indicating a strong relationship between the actual and predicted values. According to the Mean Square Error values, the tangent sigmoid transfer function outperformed the others, giving a value of 1.0813, indicating better predictions of the soil nitrogen, phosphorus, and potassium content from the model.

Combination of Phytoextraction and Biochar Improves Available Potassium and Alters Microbial Community Structure in Soils

This study aimed to assess the effectiveness of combining phytoextraction and biochar for metal-polluted wetland soils by exploring the changes in soil biochemical properties, especially compared to the outcomes of single phytoremediation or biochar application. Soil biochemical properties serve as reliable indicators of soil quality and exhibit a high sensitivity to microbial community dynamics. Phytoextraction is via the native plants Phragmites australis (P. australis) and Suaeda salsa (S. salsa). The addition of biochar significantly increased the total organic carbon (TOC) and available potassium (AK) contents in the rhizosphere soil of P. australis and more in that of S. salsa. The effects of the combined remediation on the composition of the main classes of bacteria are uncertain, and the abundance of the main fungal classes decreased. At the level of OTU, no significant differences were observed in the richness and diversity of microbial communities between the single and combined remediation approaches. On a genus level, the combined remediation of biochar and S. salsa had the highest specificity of soil bacteria, while the single biochar remediation gave the highest specificity of soil fungi. At the class level, the four most abundant classes of bacteria were actinobacteria, alphaproteobacteria, gammaproteobacteria, and bacterricilineae. Biochar addition decreased the abundance of actinobacteria in P. australis rhizosphere soil but increased the abundance of actinobacteria in S. salsa rhizosphere soil. The sordariomycetes and eurotiomycetes were the dominant fungal classes. The combined remediation reduced the abundance of sordariomycetes, and the abundance of eurotiomycetes decreased after single phytoextraction, biochar, and combined remediation.

Combination of Fertilizer and Growth Regulators Impact on Nutrient Balance in Wheat Crop (Triticum aestivum L.)

A field experiment was conducted during the rabi season of 2020 at All India Coordinated Research Project (AICRP) on Wheat, Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur (M.P.) to evaluate nutrient balance under the optimization of fertilizer levels with plant growth regulators. The experiment was laid out in a randomized block design comprising nine treatment of different dose of fertilizer along with plant growth regulators namely chlormequat chloride and tebuconazole applied at the rates of 0.2% and 0.1%, respectively and replicated three times. The recommended dose of fertilizer, 120:60:40 kg NPK ha-1 was applied as per treatment. The result showed that using 150% recommended doses of NPK, recorded higher value of available nitrogen (297.320 kg ha-1), phosphorus (18.970 kg ha-1) and potassium (311.630 kg ha-1) content in soil after the harvest of wheat was significantly influenced by the application of different doses of fertilizer, while lowest available content of all the three major nutrients was recorded from control. Growth regulators had no significant influence on the available nitrogen, phosphorus and potassium content in soil. The highest nitrogen content in both grain and straw were observed with the application of 150% recommended doses of NPK with growth regulators (1.99%) and (0.567%), respectively. Phosphorus content and potassium content both in grain and straw were significantly influenced by fertilizer doses, highest value recorded with 150% recommended doses of NPK and the lowest phosphorus and potassium content in both grain and straw were recorded in control while all the other treatments receiving fertilizers with or without being at par with each other. Uptake of all the major nutrients viz., nitrogen, phosphorus and potassium showed the similar trend with significantly highest uptake recorded with the application of 150% recommended doses of NPK with growth regulator and optimal NPK application demonstrated a positive nutrient balance in the soil. It concluded that nutrient management with growth regulator in wheat, economically viable and ecologically sound option to extend these benefits of balanced nutrition in enhancing both crop production and soil heath.

Enhancing maize productivity by mitigating alkaline soil challenges through acidified biochar and wastewater irrigation

In alkaline soil conditions, the availability of essential nutrients for plant growth becomes limited, posing a significant challenge for achieving optimal maize growth and yield. Exploring the impact of biochar and waste irrigation on soil alkalinity and maize production in arid regions has received limited attention. This study aimed to evaluate the effects of three levels of acidified biochar (0, 5, and 10 Mg ha−1) in two growing seasons of maize—spring and autumn. The treatments were applied following a randomized complete block design with three replications. Biochar was applied only in the autumn season, and its residual effects were evaluated in the spring season. The study found that using acidifying biochar at a rate of 10 Mg ha−1 significantly increased maize yield by 35.8% compared to no application and by 16.4% compared to a rate of 5 Mg ha−1. In the autumn, applying acidified biochar at 10 Mg ha−1 reduced soil pH by 3.65% and 6.41% compared to 0 and 5 Mg ha−1. In the spring, the same application led to a decrease in soil pH by 5.84% and 7.37% compared to the lower rates. Additionally, using 10 Mg ha−1 of acidifying biochar increased soil phosphorus concentration by 87.6% and soil potassium concentration by 38.0% compared to not using biochar, and by 46.2% and 35.0% compared to the 5 Mg ha−1 application. These findings suggest that the reduction of soil pH by applying biochar at a rate of 10 Mg ha−1 facilitated an increase in nutrient availability in the soil, consequently leading to higher maize yield. Notably, no significant differences were observed in maize productivity and soil properties between the spring and autumn seasons. Therefore, this study paves the way for further exploration into the long-term effects of acidifying biochar on maize productivity and soil properties in similar agroecological contexts.

Soil properties following borrow pit reclamation with insufficient topsoil amended with peat and biochar

AbstractDisturbed sites, such as borrow pits and oil and natural gas well sites, require reclamation to restore and sustain levels of productivity similar to those prior to the disturbance. However, salvaged topsoil at many sites is often insufficient to meet the 80% topsoil replacement depth (TRD80) required for successful reclamation in western Canada. This 5‐year study evaluated soil responses to 50% topsoil replacement depth without organic amendment (TRD50) or amended with either peat (PTRD50) or biochar (BTRD50), relative to the TRD80 treatment (Control), following borrow pit reclamation at a disturbed boreal site near Cold Lake, Alberta, Canada. Amendments were applied once at rates calculated to raise the soil organic carbon (SOC) content in the TRD50 soil to a level equal to that in the TRD80 treatment. Results showed a 143%, 87%, and 116% increase in total Kjeldahl nitrogen concentration in the PTRD50 relative to the TRD80, TRD50, and BTRD50 treatments, respectively, while soil potassium (K) concentration was significantly greater for BTRD50 than PTRD50. Peat and biochar significantly increased SOC concentrations by 83% and 88%, respectively, relative to the mean of TRD80 and TRD50 treatments. Our results show that peat and biochar can improve soil properties of disturbed boreal sites reclaimed with insufficient salvaged topsoil to a level suitable for successful reclamation. This has important implications on the reclamation of a multitude of disturbed sites, in Canada and globally, that have insufficient volumes of salvaged topsoil needed for successful reclamation.