Potassium Chloride Fertilizers Research Articles

Down-streaming Small-Scale Green Ammonia to Nitrogen-Phosphorus Fertilizer Tablets for Rural Communities

This study aims to evaluate the growth and production of sweet corn plants in response to the application of commercial NPK fertilizer and various doses of nitrogen-phosphorus fertilizer tablets. From early October 2022 to late January 2023, research was conducted at Research and Development Luas Birus Utama to produce nitrogen-phosphorus fertilizer tablets and at Research and Development Syngenta Indonesia Cikampek Station, Karawang, to perform a semi-field analysis. A factorial randomized block design with two treatment factors was employed in this study. The first factor was five types of nitrogen-phosphorus fertilizer tablets, namely, A (0% nitrogen and 6.3% phosphorus), B (0.81% nitrogen and 6.3% phosphorus), C (1.57% nitrogen and 6.1% phosphorus), D (2.33% nitrogen and 6.2% phosphorus), and E (3.06% nitrogen and 6.2% phosphorus). The second factor was F (standard nitrogen, phosphorus, and potassium). The results revealed that applying different dosages of nitrogen-phosphorus fertilizer tablets in combination with potassium chloride fertilizer yielded no different effect on the growth, biomass, and yield components of sweet corn plants when compared to applying NPK fertilizer. A comparison between the soil test results before and after application revealed that the formulation of fertilizers in tablet form helps plants to effectively absorb the required nutrients. It is currently possible to develop small-scale or microscale green ammonia production technology to fulfill the fertilizer requirements of rural communities because of its low cost, low carbon emissions, and low renewable energy consumption. The scarcity of fertilizer supplies endangers Indonesia’s food sustainability. Nitrogen-phosphorus fertilizer tablet production technology can be used in areas with a scarcity of inorganic fertilizers but with the potential for low-grade phosphate mines using commercial ammonia solutions. Thus, understanding how to produce nitrogen-phosphorus fertilizer tablets from ammonia solution will aid in the acceptance of microscale green ammonia production technology. Doi: 10.28991/ESJ-2024-08-02-016 Full Text: PDF

Effect of Compost, Blended (NPSZn), and Potassium Chloride Fertilizers on Soil Bulk Density and Moisture Content in Two Soil Textural Groups of Tigray, Northern Ethiopia

The growing needs for agricultural production require maintaining and improving soil fertility through fertilization. However, most research to date in Ethiopia particularly in the Tigray regional state has focused on the effects of soil chemical properties and relatively little work has been done on soil physical properties. The objective of this study was to assess the effects of compost, blended (NPSZn), and potassium chloride (KCl) fertilizers on soil bulk density (BD) and moisture content (SMC). Therefore, a field experiment was carried out for 2018-2019 years to study the influence of sole and combined application of compost, NPSZn, and KCl fertilizers on BD and SMC in clay loam and loamy sand soil textures in Tigray. Two compost (0 and 20 t·ha−1), three NPSZn (0, 60, and 120 kg·ha−1), and four KCl (0, 120, 210, and 300 kg·ha−1) rates replicated three times were arranged in split-split plot design and allocated to main, sub, and sub-subplots, respectively. BD (g·cm−3) and SMC (%) data were collected from 0 to 10 and 0 to 30 cm soil depths before and after harvesting in 2018 and 2019, respectively. Sole and combined application of the fertilizers considerably influenced BD and SMC in both soil textural groups and years. Compost applied in combination with NPSZn at 120 kg·ha−1 and KCl at 300 kg·ha−1 significantly reduced BD (1.24 g·cm−3 in 2018 and 1.22 g·cm−3 in 2019) in clay loam soils as compared to all treatments. Similarly, the lowest BD (1.5 g·cm−3 in 2018 and 1.47 g·cm−3 in 2019) was observed in loamy sand soils. The highest volumetric SMC (21% in both years) was observed in clay loam soil in plots treated with compost. Likewise, the highest SMC (12% in 2018 and 11% in 2019) was found in loamy sand soils in compost-treated plots. This study demonstrated that SMC and BD can be improved through compost and compost combined with NPSZn and KCl application, respectively, in the drylands of Northern Ethiopia.

Application of potassium fertilizer and plant growth regulators to the growth and productivity of purple sweet potato

The study aimed to determine the effect of plant growth regulators and potassium fertilizer on the growth and productivity of three clones of purple sweet potato. The experiment was conducted at IPB University experimental station in Leuwikopo Dramaga Bogor for seven months. The study used a split-plot design with three factors and three replications. The first factor was as a subplot, namely plant growth regulators (PGR) application which consisted of two levels of without PGR (S0) and with PGR (S1) concentration of 2 cc l-1 of water (2,000 ppm). The second factor was as a subplot, namely rates of potassium chloride fertilizer (60, 120, 180 kg ha-1 K2O). The third factor as the main plot was sweet potato clones of (K1) Ayamurasaki, (K2) RIS-03063-05, and (K3) MSU 03028-10. The concentration of 2,000 ppm PGR did not significantly affect growth and tuber yield components. Potassium chloride K2O of 60 kg ha-1 up to 180 kg ha-1 did not significantly affect growth and tuber yield components. MSU 03028-10 clone had the highest total tuber yield (1537.8), healthy tuber (1529.9), unmarketable tuber (740.3), and small tuber (709.0). MSU 03028-10 clones have the longest stem length and the largest number of leaves 3-12 WAP. This study indicates that the MSU 03028-10 clone produces better growth and productivity than other clones.

Synthesis and Application of Modified Lignin Polyurea Binder for Manufacturing a Controlled-Release Potassium Fertilizer

Conventional potassium chloride granules have inefficient applications in agricultural production due to particle irregularity and low fluidity. The application of controlled-release potassium chloride could increase the potassium-use efficiency and alleviate the shortage of potassium ore resources. In this study, a well-rounded potassium chloride fertilizer core was prepared, using the graft modification of polyurea to enhance the coating rate and release performance. The adhesive and tensile characteristics of the modified polyurea binder, as well as the granule properties of modified polyurea binder potassium chloride, were studied to determine the ideal lignin-grafted ratio. The effect of the modified polyurea binder with potassium chloride on the properties of coated fertilizer was investigated. The findings, shown by radar maps of the binder’s properties, demonstrated that the ideal mass ratio of the modified lignin polyurea binder to urea is 1:2. The Fourier-transform infrared spectroscopy results demonstrated that the amino functional groups of lignin were enhanced, improving the product’s interfacial compatibility with the polyurea matrix. Compared to humic acid (HA; 12%) and bentonite (Ben; 30%) treatments, the granule intensity of the 9.9%—1:2 treatment considerably increased by 139.10% and 38.86%, respectively, while the static angle of the granules reduced by 16.67% and 3.81%. The 28-day cumulative release rate of the modified polyurea (9.9%—2:1) with a 5% coating thickness was the lowest (28%), 42% lower than that of the lowest conventional treatment. In summary, the creation of a bio-lignin polyurea binder under the optimum conditions reduced the need for petrochemical-based materials, allowed the preparation of fertilizer with granules of increased fluidity, and enabled the successful coating of a high-salt potassium fertilizer, offering a novel technique for the high-value application of potash fertilizer coating.

PATTERN OF POTASSIUM RELEASE FROM SLOW RELEASE FERTILIZER POTASSIUM CLORIDE-BENTONITE FERTILIZER

Potassium has an important role in the process of plant growth, but its presence and availability in the soil are limited, because potassium is easily lost and flows out by water. Increasing the efficiency of potassium fertilization can be pursued through the formulation of fertilizer in the form of slow-release fertilizer (SRF) using bentonite. This study aimed to determine the release of potassium in potassium chloride fertilizer into the soil after bonding with acid-activated bentonite coated with potassium chloride. The composition of the KCl fertilizer made varies with bentonite with a mass ratio (g) of 1:1; 2:1; 3:1; 4:1; and 5:1, with a percolation time of 28 days. The concentration of released potassium was determined using an atomic absorption spectrophotometer. Material characterization was carried out by FTIR. The results showed that the ratio 1:3 had the highest potassium content of 45.12% with an incubation time of 28 days. The concentration of released potassium on day 7; 14; 21; and 28 respectively (12.55±1.25)%, (28.39±1.49)%, (5.,91±0.98)%, and (70.49±1.36)% . The results of the characterization of the determination of the fungal group on SRF3 were not significantly different from that of activated bentonite. Even though there were differences in the intensity of certain peaks and changed the functional groups.

Hydrophobic coatings for granular fertilizers to improve physical handling and nutrient delivery

Globally, fertilizer agglomeration (caking) during transport and storage leads to irreversible breakdown, dust, equipment blockages and inconsistent field application. Coatings which are hydrophobic reduce moisture uptake at high humidity and reduce caking but still need to release plant nutrients. Here, natural and synthetic waxes coated onto fertilizer granules with powders to impart surface roughness reduced contact between condensed water droplets and the surface, lowering moisture ingress. The adhesive strength of the coatings and rate of nutrient release are shown with degree of roughness quantified using laser surface microscopy. The wax-only coatings on potassium chloride fertilizer (MOP, 50% K) reduced moisture uptake by up to 30%, while for coatings with wax and roughener reductions were between 56% and 80%. Beeswax with micronutrient rougheners reduced moisture uptake by over 65% whilst maintaining uninterrupted nutrient supply. Thus, these hydrophobic coatings can improve physical characteristics of fertilizer without compromising the kinetics of nutrient release.

Radioactive Concentrations in Chemical Fertilizers

Background: The aim of the present study was to determine radioactive concentrations in fertilizers known to contain essential nutrients. Results of this study could be used as basic data to monitor the impact of chemical fertilizers on the environment and public health. Nitrogen fertilizers, calcium fertilizers, sulfur fertilizers, phosphate acid fertilizers, and potassium chloride fertilizers were used in this study.Materials and Methods: Five chemical fertilizers were pulverized, placed in polyethylene containers, and weighed. The time to measure each specimen was set to be 3,600 seconds for a scintillator-based gamma-ray spectroscopy system. Concentration of gamma radionuclide was analyzed based on obtained spectra. At the end of the measurement, the spectrum file was stored and used to calculate radioactive concentrations using a gamma-ray spectrometer software.Results and Discussion: In the nitrogen fertilizer, 3.49 ± 5.71 Bq/kg of <sup>137</sup>Cs, 34.43 ± 7.61 Bq/kg of <sup>134</sup>Cs, and 569.16 ± 91.15 of <sup>40</sup>K were detected whereas <sup>131</sup>I was not detected. In the calcium fertilizer, 5.74 ± 4.40 Bq/kg of <sup>137</sup>Cs (the highest concentration among all fertilizers), 22.37 ± 5.39 Bq/kg of <sup>134</sup>Cs, and 433.67 ± 64.24 Bq/kg of <sup>40</sup>K were detected whereas <sup>131</sup>I was not detected. In the sulfur fertilizer, 347.31 ± 55.73 Bq/kg of <sup>40</sup>K, 19.42 ± 4.53 Bq/kg of <sup>134</sup>Cs, 2.21 ± 3.49 of <sup>137</sup>Cs, and 0.04 ± 0.22 Bq/Kg of <sup>131</sup>I were detected. In the phosphoric acid fertilizer, 70,007.34 ± 844.18 Bq/kg of <sup>40</sup>K (the highest concentration among all fertilizers) and 46.07 ± 70.40 Bq/kg of <sup>134</sup>Cs were detected whereas neither <sup>137</sup>Cs nor <sup>131</sup>I was detected. In the potassium chloride fertilizer, 12,827.92 ± 1542.19 Bq/kg of <sup>40</sup>K was and 94.76 ± 128.79 Bq/kg of <sup>134</sup>Cs were detected whereas neither <sup>137</sup>Cs nor <sup>131</sup>I was detected. The present study examined inorganic fertilizers produced by a single manufacturer. There might be different results according to the country and area from which fertilizers are imported. Further studies about inorganic fertilizers in more detail are needed to create measures to reduce <sup>40</sup>K.Conclusion: Measures are needed to reduce radiation exposure to <sup>40</sup>K contained in fertilizers including phosphoric acid and potassium chloride fertilizers.

Toward the replacement of conventional fertilizer with polyhalite in eastern China to improve peanut growth and soil quality

Abstract Background Polyhalite fertilizer application is an effective way to alleviate a shortage of potassium. This study explored the effects of polyhalite fertilizer application as a total or partial replacement for conventional potassium fertilizer to improve peanut growth and soil quality. Results The index of peanut yield and its economic benefits, the content and distribution of mineral nutrients in different organs, soil chemical properties, and rhizosphere microbial diversity in response to the treatments were examined. The results show that the M4P6T treatment (60% polyhalite fertilizer replacing potassium chloride as the base fertilizer, and 40% potassium chloride fertilizer applied as a topdressing) increased profit by 7.2% without affecting the yield. The M4P6T treatment significantly improved the accumulation and distribution of potassium, calcium and magnesium in the kernels compared with the M10B treatment (no polyhalite fertilizer; potassium chloride fertilizer only as the base fertilizer). Soil treated with polyhalite fertilizer had higher alpha-diversity values and greater relative abundance of microbes at the phylum and genus levels. Conclusions Partial substitution of polyhalite for potassium chloride improved soil quality and peanut growth more than did single applications of polyhalite and potassium chloride. Graphical Abstract

Advance Time to Determine Injection and Flushing Times in Drip Fertigation

Drip fertigation has shown unquestionable benefits in recent decades compared to traditional farming fertilization practices. However, a fertilizer dissolved in the irrigation water must be evenly distributed in the fertigated area. Irrigation system and fertigation system characteristics and operational management potentially affect the uniformity of fertilizer and water distribution. Advance time (AT), which is an intrinsic and determinable characteristic of the irrigation system, has not been assessed as a useful technical criterion for managing the uniformity of fertilizer distribution in drip fertigation. The objective of this study was to assess the use of advance time as a technical criterion for determining the duration of injection time and flushing time that provides a satisfactory uniformity of spatial distribution of the fertilizer in drip fertigation. Therefore, the distribution uniformity of potassium chloride (KCl) fertilizer and water was evaluated at six injection times equivalent to 25, 50, 75, 100, 150, 200% AT, and two flushing times equivalent to 100 and 200% AT through Christiansen’s uniformity coefficient (CU) and distribution uniformity (DU). The used drip irrigation system had 10 drip strips with 12.5 m length, a flow rate of 1.40 L h−1 per dripper, and AT of 12.5 min. The injection solution was prepared with 40 g L−1 of KCl. The results indicate that the distribution uniformity of KCl improved significantly with increasing injection time. The injection time of 200% AT promoted the greatest uniformity of distribution of KCl with CU of 0.977 and DU of 0.962. The flushing time of 100% AT was sufficient to rinse the irrigation system and promoted a satisfactory spatial distribution uniformity with a CU of 0.983. In both tests, the uniformity of irrigation water distribution was satisfactory, with CU of 0.988 and DU of 0.982 (average). Advance time is an intrinsic characteristic of the irrigation system that is useful in determining the duration of injection time and flushing time in a more technical way for drip fertigation with satisfactory spatial distribution uniformity of the fertilizer.

Effect of blended fertilizer types for improving production of sorghum (Sorghum bicolor L.) in Bena Tsemay district, Southwestern Ethiopia

Depletion of soil organic matter, depletion of macro- and micronutrients, lack of local specific fertilizer recommendation per commodity are among core constraints in Ethiopian soils that hinders crop production including sorghum. The experiment was conducted to evaluate blended fertilizer type effect on improving production of sorghum in Bena Tsemay district, Southwestern Ethiopia. The experiment was carried out in 2018 and 2019 main cropping season and laid out in RCBD following three replications with spacing of 75cm between rows and 20cm between plants. It was done by using control, (46N+68.7P2O5) kgha-1 , (142NPS+141Urea) kgha1 , (150NPSB+141Urea) kgha-1 , (160NPSBZn+144Urea) kgha-1 , (155NPSZn+141Urea) kgha1 , (197NPSBK+141Urea) kgha-1 and (207NPSBZnK+141Urea) kgha-1 treatments. Full dose of blended fertilizer, phosphorus, boron and potassium chloride fertilizers were applied at planting time and urea was applied in two split. Partial budget analysis with dominance and marginal analysis was done for economic evaluation. The result has revealed that sorghum has responded well to the application of macronutrients with micronutrients (Zn and B) than unfertilized. Application of 150kgha-1NPSB+141kgha-1Urea resulted in highest grain yield, while the lowest grain yield was recorded from the control. The highest economic returns of 230.06% was obtained from application of 150kgha-1NPSB+141kgha-1Urea; and it gives 43.85% yield increment and 31.86% increment in economic return over the control. Application of 150kgha-1NPSB+141kgha-1Urea was recommended for farmers and investor’s to produce sorghum on the study area and similar agro ecologies, as it was optimum for improving sorghum production. Further investigation should be done on plant nutrient uptake, nutrient use efficiency and optimization.

Performance optimisation of forward-osmosis membrane system using machine learning for the treatment of textile industry wastewater

Forward osmosis (FO) is an emerging low energy membrane-based technology and can be applied if the diluted draw solution (DS) is directly utilized without additional recovery/treatment. In this study, FO process was applied for the treatment of textile industry wastewater using fertilizer as DS. This paper focuses on modelling and optimisation of FO process using machine learning techniques like Response Surface Methodology (RSM), Artificial Neural Network (ANN) and Adaptive Neuro-Fuzzy Inference System (ANFIS). To model the FO process, central composite design was utilized to examine the effect of initial draw concentration, initial feed concentration, time, initial feed pH and temperature on the water flux and reverse salt flux. The optimum water flux (8.527 L.m−2.h−1 (LMH)) and reverse salt flux (7.246 g.m−2.h−1 (GMH)) was obtained using initial draw concentration of 1.625 M, initial feed concentration of 1090 mg/L, reaction time of 90 min, initial feed pH of 7.33 and temperature of 35 °C. Under these conditions, FO performance was carried out experimentally and validated with the models. The model developed for the FO process by ANN and RSM was considerably better than that of other models in terms of precision of predicting the water flux and the reverse salt flux, respectively. About six different chemical fertilizer solutions were screened and tested at optimum conditions to identify the best suitable fertilizer DS for FO process using textile wastewater. The results indicate that Diammonium Phosphate (DAP) along with Potassium Chloride (KCl) fertilizer as DS gave better performance with respect to water flux.

Potassium chloride fertilization of potatoes: nutrient uptake rate and tuber yield of cultivars Ágata and Atlantic

ABSTRACT Potassium (K) is the nutrient taken up in the greatest quantity by the potato plant. Obtaining information about the relationship between tuber yield and K application rate allows improvements in fertilizer use efficiency. We aimed to evaluate the variation in potassium fertilizer doses in uptake rate of other nutrients and in potato tuber yield. The experiments were carried out in Unaí-MG testing cultivars Ágata and Atlantic and in Mucugê-BA evaluating cultivar Ágata. The experimental design used was randomized blocks. We studied the rates of 0; 70; 110; 220, and 450 kg ha-1 K2O. The increase in K rate reduced the levels of S, Ca, Mg and B in Atlantic-Unaí, Ca, Mg, Zn and B in Ágata-Unaí and S, Fe and B in Ágata-Mucugê. The cultivar Atlantic-Unaí did not respond to the increase of potassium fertilizer dose, with a total of 32.3 to 37 t ha-1. Cultivars Ágata-Unaí and Ágata-Mucugê responded to rates estimated at 225 and 166 kg ha-1 K2O with the highest productivities of 53.9 and 56.2 t ha-1, respectively.

Chloride source delineation in an urban‐agricultural watershed: Deicing agents versus agricultural contributions

AbstractAnalyses (n = 525) of chloride (Cl−), bromide (Br−), nitrate as nitrogen (NO3‐N), sodium (Na+), calcium (Ca2+) and potassium (K+) in stream water, tile‐drain water and groundwater were conducted in an urban‐agricultural watershed (10% urban/impervious, 87% agriculture) to explore potential differences in the signature of Cl− originating from an urban source as compared with an agricultural source. Only during winter recharge events did measured Cl− concentrations exceed the 230 mg/L chronic threshold. At base flow, nearly all surface water and tile water samples had Cl− concentrations above the calculated background threshold of 18 mg/L. Mann–Whitney U tests revealed ratios of Cl− to Br− (p = .045), to NO3‐N (p < .0001), to Ca2+ (p < .0001), and to Na+ (p < .0001) to be significantly different between urban and agricultural waters. While Cl− ratios indicate that road salt was the dominant source of Cl− in the watershed, potassium chloride fertilizer contributed as an important secondary source. Deicing in watersheds where urban land use is minimal had a profound impact on Cl− dynamics; however, agricultural practices contributed Cl− year‐round, elevating stream base flow Cl− concentrations above the background level.

The potential for potassium chloride fertiliser applications to leach cadmium from a grazed pasture soil

Cadmium (Cd) is a biotoxic element that can enter the human food chain via plants grown in Cd-enriched soil. Chloride (Cl) can solubilise Cd in soil. Although fertilisers containing Cl are not recommended as they may increase plant uptake of Cd, potassium chloride (KCl) is regularly applied to replenish and maintain K in the soil of grazed pastures. A trial was conducted to see if an autumn application of low (0.02 mol L−1, equivalent to 30 kg K ha yr−1) or high (0.04 mol L−1) KCl and the same molar rates of CaCl2 (used as a check to other studies) would leach Cd over 4-months of normal (300-mm) or high (600-mm) autumn-winter rainfall without enriching Cd in plant shoots. Leaching losses of Cd were greater from the high KCl and CaCl2 treatments (1.80 and 1.70 g ha−1, respectively) than the low KCl treatment (1.27 g ha−1). All loads lost from the Cl treatments were greater than from the control treatment (0.53 g ha−1). Losses from Cl treatments represented 29–41% of the Cd applied in an annual application of 250 kg superphosphate ha−1. Pasture shoot Cd concentrations were not different to the control (mean = 0.088 mg kg−1). Applying Cl (e.g. as KCl) in autumn may be a simple strategy to help slow the enrichment of soil Cd and does not increase the uptake of Cd by pasture shoots.

Quantifying and Mapping Atmospheric Potassium Deposition for Soil Ecosystem Services Assessment in the United States

National Atmospheric Deposition Program (NADP) databases are important for quantifying and mapping the contribution of atmospheric deposition to soil provisioning ecosystem services. These databases provide information about the atmospheric deposition of potassium (K+) which is an essential element and component of many fertilizing materials. Atmospheric deposition flows (wet, dry, and total) serve as one input of K+ to soils; however, deposition varies spatially across the United States (U.S.). This study ranked an estimated provisioning value of soil ecosystem services due to atmospheric K+ deposition within the contiguous U.S. by state and region based on the 16-year period from 2000 to 2015. The total provisioning ecosystem value of atmospheric potassium deposition was over $406M (i.e., 406 million U.S. dollars) ($179M wet + $227M dry) per year based on a 5-year moving average of $500 per metric ton of potassium chloride (KCl) fertilizer in the U.S. The highest ranked regions for total value of K+ deposition per year were: 1) West ($86.5M), 2) South Central ($80.4M), and 3) Southeast ($80.2M). The highest ranked states for total value of K+ deposition per year were: 1) Texas ($44.3M), 2) California ($18.3M), and 3) New Mexico ($1.35M). Atmospheric potassium deposition is a source of K which is essential for human health. Given a U.S. population of 325.7 million people (2017), and a recommended daily intake of 4.7 g per person per day of K, it would require at least 1531 metric tons/day of potassium to ensure that every person is able to meet their daily potassium requirement. In terms of monetary value, it will cost nearly $1.5M per day based on a moving 5-year average U.S. price of $500 per metric ton of KCl fertilizer. The results of this study provide a methodology to estimate and map the value of atmospheric potassium deposition for ecosystem services assessments, which can be helpful in conducting nutrient audits at various scales to address the United Nations (UN) Sustainable Development Goals.

Mapping spatial distribution of soil properties using electrical resistivity on a long term sugarcane trial in South Africa

In experimental trials the spatial distribution of soil properties is a key factor to evaluate and determine the credibility of the research outcomes. To evaluate the spatial distribution of soil properties at different depths in the present study, the electrical resistivity method was selected because of its non-destructive nature and high spatial resolution.The investigation was conducted on BT1 (Burning versus mulching) the world's oldest sugarcane trial (established 25 October 1939) located on the premises of the South African Sugarcane Research Institute (SASRI). The experimental area, covering 7200 m2, is divided in 32 plots with three crop residue retention treatments. These treatments are either fertilized and not fertilized. The RM15 resistance-meter equipped with a multiplexer was used to collect geophysical data. The latter was used to generate apparent electrical resistivity maps corresponding to three approximate depth ranges: (0–0.5 m, 0–1.0 m and 0–2.0 m). The spatial resolution of the shallowest map (0–0.5 m), was 0.5 m × 1.0 m. Bulk density and soil water content, for the 0–0.1 m depths, were also determined from samples collected on a grid of 4 m × 5 m. All data collected were georeferenced using a spatial resolution of 4 m × 1 m with the Digital Elevation Model (DEM).The results of this survey showed the effectiveness of geophysical mapping to reveal detailed information regarding soil spatial variability and to understand and establish the relationships between soil fertility and soil physical properties. Detailed analysis of these results led to the identification of two different soil types on the trial site: a Mollic Cambisol in the upper slope of the trial with a depth of <1.0 m and a deeper Mollic Nitisol in the lower slope. Additionally, close to the southern edge of the site, higher values of electrical resistivity revealed a layer of colluvial deposits, that has not been considered in the past. The relationships between electrical resistivity and investigated soil properties (soil water content, bulk density, aggregate stability and fertilizer) initially seemed paradoxical. Although there is still a need for further investigations, the current study decently establishes the rather unexpected relationships. The most striking finding was the high resistivity in fertilized plots associated with the application of potassium chloride fertilizer which led to a decreased soil aggregate stability.

Life cycle assessment of potash fertilizer production in China

Fertilizer application leads to energy consumption and greenhouse gas (GHG) emissions. In this study, aiming to quantify the environmental impacts generated from brine-based potassium chloride fertilizer production, a life cycle assessment study was conducted. Additionally, uncertainty analysis based on Monte Carlo was conducted to improve the reliability of results obtained from this study. Results show that potential impacts from global warming category and fossil depletion category contributed the most to the total environmental impacts, with the value of 1.90E+02 kg CO2 eq (GSD2 = 1.35) and 2.57E+01 kg oil eq (GSD2 = 1.39), respectively. Impacts generated from respiratory inorganics and water depletion category also had significant contributions, with additional contributions from the categories of terrestrial acidification, respiratory organics, non-carcinogens, carcinogens, and marine eutrophication. Key factors analysis uncovers that the overall environmental impacts were mainly caused by electricity generation, water consumption, and on-site emissions. Finally, suggestions based on research results and the local reality are proposed. Research findings from this study provide valuable insights to stakeholders so that the overall environmental impacts (specially for GHG emissions) from potash fertilizer production can be mitigated.

Rye cover crop increases earthworm populations and reduces losses of broadcast, fall-applied, fertilizers in surface runoff

Corn (Zea mays L.) silage and soybean [Glycine max (L.) Merr.] rotations in the US Upper Midwest leave minimal amounts of surface residues, which can contribute to soil degradation, increased surface runoff, and reduced water quality. Planting cover crops after harvest can reduce these concerns, but their effectiveness in reducing nutrient losses in surface runoff shortly after fall planting and fertilization has not been thoroughly investigated. Therefore, we applied 65 mm of simulated rainfall in 60 min to five replicate, 1.5 by 3.0 m, field plots in a no-till, corn silage-soybean rotation into which a rye (Secale cereale L.) cover crop was planted for 14 consecutive years and to five replicate plots with no cover crop history. Natural slope of the plots ranged from 0.1 to 2.7%. The study was conducted in October 2014, about one month after corn silage harvest and rye planting and ∼1 h after broadcast application of monoammonium phosphate and potassium chloride fertilizers. The living rye cover crop significantly (P ≤ 0.05) delayed surface runoff by 5.7 min and decreased total runoff by 65% compared to plots with no cover crop. This resulted in a significant 68% reduction in sediment loss and even greater significant reductions in fertilizer nutrient losses (i.e., NH4-N - 86%; total P - 83%; total dissolved P - 84%; K - 91%). Earthworm population and biomass, measured using electrical extraction shortly after the rainfall simulations, were 1.2 and 1.4 times greater in cover crop plots than in no cover plots and 3.2 and 2.5 times greater the following spring. Our results suggested that a living cover crop and their long-term usage can contribute to improvements in soil structure and increased earthworm populations that can substantially reduce sediment and nutrient losses in surface runoff due to a severe storm shortly after post-harvest broadcast application of fertilizer.

Potassium fertilisation reduces radiocesium uptake by Japanese cypress seedlings grown in a stand contaminated by the Fukushima Daiichi nuclear accident

We analysed suppressive effects of potassium (K) fertilisation on radiocesium (137Cs) uptake by hinoki cypress (Chamaecyparis obtusa) seedlings from soils contaminated after the Fukushima Daiichi Nuclear Power Plant accident. Three-year-old seedlings were planted in a clear-cut forest (ca. 4 ha) during June–July 2014, and potassium chloride fertiliser (83 kg K ha−1) was applied twice (August 2014 and April 2015). 137Cs concentrations in the needles in the fertilised plots were one-eighth of those in the control (unfertilised) plots at the end of the second growing season (October 2015). Our results clearly indicated that K fertilisation reduced radiocesium transfer from soil to planted cypress seedlings. A linear mixed model analysis revealed that 137Cs concentrations in the needles were significantly affected by 137Cs inventory in the soil (Bq m−2) adjacent to the sampled seedlings, exchangeable K concentrations in surface mineral soils (0–5 cm) and fertilisation. The exchangeable K concentrations in surface soils in October 2015 did not differ from those in August 2014 (before fertilisation) in the fertilised plots and in the control plots. These results suggested that the levels of exchangeable K would temporarily increase by fertilisation during the growing season, and radiocesium uptake by tree roots was suppressed.

Effects of polymer-coated potassium chloride on cotton yield, leaf senescence and soil potassium

Potassium (K) is one of the most important nutrients influencing plants, including cotton growth and metabolism. Because of toxicity from chloride ions, potassium sulfate (K2SO4) usually is used instead as a potassium fertilizer, especially for cotton, although it is lower in K2O content and dearer than potassium chloride (KCl). The objective of this study was to investigate the effects of polymer-coated potassium chloride (PCPC) fertilization on cotton yields, yield components, fiber qualities, potassium use efficiencies and leaf senescence under saline conditions. A 2-yr field experiment was conducted in the Yellow River Delta of China with a high-yielding cotton cultivar (‘Guoxin 99-1’). The experiment had the following six treatments with varying potassium fertilization: 70% PCPC mixed with 30% K2SO4 applied once before planting; PCPC applied once before planting; K2SO4 (KCl) applied twice with one application (40%) before planting and second application (60%) during first bloom stage; K2SO4 (KCl) applied once before planting; and fertilization none potassium as the control. The release rate of PCPC appeared to be slow before the squaring stage, but accelerated between the first bloom and boll-setting stages, and then decreased during the late stage including harvest. The number of cotton bolls was 8.99–19.71% higher and seed yields 4.39–28.10% higher, in 70% PCPC mixed with 30% K2SO4 treatment than in the other potassium fertilizer treatments. Also, the potassium recovery efficiency and net profits were increased by 3.38–40.90% and 5.77–137.26%, respectively, in the 70% PCPC mixed with 30% K2SO4 compared with the other potassium fertilizer treatments. Available soil potassium contents, fiber qualities and leaf photosynthetic indices were all significantly improved by using PCPC instead of the more standard potassium fertilizers. Hence, combining PCPC with K2SO4 at a 7:3 potassium ratio can delay leaf senescence, increase yields and fiber qualities, and improve potassium use efficiencies and economic benefits in cotton.