Potash Research Articles

Evaluation of five soil nutrient extraction methods for practical assessment of phosphorus and potassium availability for tomato (<i>Solanum lycopersicum</i>) fertilization in Andisols-Garut, Indonesia

Phosphorus and potassium are essential nutrients for plant growth and development. Plants will achieve optimum biomass and production if phosphorus and potassium needs are met through fertilization. Determining the availability of phosphorus and potassium in the soil is essential because it is related to decisions on phosphorus and potassium fertilizer rate recommendations. In this study, we evaluated 5 common phosphorus and potassium extraction methods by correlating the indicated soil nutrient levels to the relative biomass dry weight of tomato plants. The phosphorus and potassium extraction methods used were Mehlich-1, Bray-1, Morgan-Wolf, Ammonium acetate, and HCl-25%. Mean Root Error (MRE) and Root Mean Square Error (RMSE) were used to determine the precision of the linear regression equation model in predicting the relationship between phosphorus and potassium soil extraction methods and the relative biomass dry weight of tomato plants. The correlation of the soil extraction methods used in Andisols with the relative biomass dry weight of tomato was highly significant and very strong (r > 0.75) suggesting that Bray-1 was the best soil-phosphorus extraction method (P<sub>r</sub> = 0.88; P<sub>MRE</sub> = 0.10; P<sub>RMSE</sub> = 4.44), while HCl-25% was the most suitable for soil-potassium extraction (K<sub>r</sub> = 0.90; K<sub>MRE</sub> = 0.05; K<sub>RMSE</sub> = 2.95). The results of the two extraction methods will be used to determine the dosage of phosphorus and potassium fertilizers (<i>nutrient sufficiency approach</i>) for tomato plants grown in Andisols.

NPK fertilization for the first years of physic nut cultivated in two regions

The physic nut is an oilseed plant that has stood out as an alternative source for biodiesel. However, using it in this way requires determining the edaphoclimatic conditions and adequate fertilization to guarantee maximum productivity. This study objectived to evaluate and establish adequate rates of Nitrogen (N), Phosphorus (P), Potassium (K) to maximize the growth and productivity of physic nut in two edaphoclimatic conditions. Two experiments were performed over two consecutive years, one under Quartzarenic Neosol in the municipality of Diamantina and the other under Red-Yellow Latosol in the municipality of Governador Valadares. The treatments comprised rates of N: 0, 25, 50, 100 kg ha−1; P: 0, 35, 70, 140 kg ha−1; and K: 0, 40, 80, 160 kg ha−1. Plant growth was evaluated every 30 days until flowering. Seed and oil productivity was also assessed, with one harvest in Diamantina and two harvests in Governador Valadares. The edaphoclimatic condition of Governador Valadares was a determining factor in providing greater growth and productivity of the physic nut when compared to that of Diamantina. The application of N rates was unnecessary for the growth and productivity of the physic nut in Diamantina. Thus, phosphate fertilization was unnecessary in Governador Valadares and potassium fertilization was unnecessary for both regions. In Diamantina, 84 kg ha−1 and 87 kg ha−1 of P is recommended for growth and maximum productivity, respectively. Whereas, in Governador Valadares, 49 kg ha−1 and 55 kg ha−1 of N is recommended for growth and maximum crop productivity, respectively.

Effects of drip irrigation coupled with controlled release potassium fertilizer on maize growth and soil properties

Drip irrigation and the application of controlled-release fertilizers are two effective and important technical measures to conserve water and fertilizer resources and promote the growth and development of maize. However, the underlying physiological mechanism of how drip irrigation combined with controlled release potassium chloride affects maize production and soil properties remains unknown. In different soil water conditions, pot experiments were conducted during the summer maize growing season in 2022 and 2023 to measure maize grain yield, irrigation water productivity, apparent recovery efficiency of potassium, plant physiological characteristics, and soil enzyme activities under the coupling of two irrigation methods (flood irrigation and drip irrigation) and three potassium fertilizer types (potassium chloride (KCl), controlled release potassium chloride (CRK), and 70 % CRK mixed with 30 % KCl). The results revealed that drip irrigation had 6.5–8.1 % and 6.7–9.4 % higher average soil volumetric water content and 3.8–8.1 % and 4.5–13.0 % higher irrigation water productivity than flood irrigation in the two maize growth seasons, respectively. Under the drought conditions, the treatments of 70 % CRK-30 % KCl application led to a significant increase in maize yield by 9.5–10.7 % and 12.2–16.8 % and apparent recovery efficiency of potassium by 8.3–14.2 % and 10.7–10.8 % compared to CRK application treatments in 2022 and 2023, respectively. Compared with the other treatments, the treatment of drip irrigation coupled with 70 % CRK-30 % KCl application under drought conditions (DIDMK) resulted in 4.5–28.7 % and 1.1–31.9 % higher grain yield, 8.2–64.4 % and 8.6–66.8 % higher irrigation water productivity, and 5.9–28.0 % and 6.7–18.9 % higher apparent recovery efficiency of potassium in 2022 and 2023, respectively. Meanwhile, the leaf net photosynthetic rate, rubisco, catalase, peroxidase, and soil enzyme activities of DIDMK treatment were also maintained at a high level. Our results indicated that drip irrigation coupled with 70 % CRK-30 % KCl application were the optimal water and potassium supply modes for maize production. This study can provide useful information regarding summer maize sustainable production and provide theoretical and technical support for summer maize irrigation and potassium fertilizer application technologies in water-scarce regions of China and other similar regions around the world.

A distributionally robust optimization approach for the potassium fertilizer product transportation considering transshipment through crossdocks

Potassium fertilizer is an essential input for agricultural productivity, and plays a critical role in various plant processes, influencing water uptake, enzyme activation, and photosynthesis. The efficient delivery of potassium fertilizer products to the end-users, typically farmers and agricultural enterprises, is of utmost importance. Due to the long traveling distance between the supplier and customers, decision makers of supplier normally set up multiple crossdocks to aid in transition and storage of potassium fertilizer products. In this situation, making an optimal transportation plan as well as the inventory level of crossdocks will directly enhance the efficiency and effectiveness of long-distance transportation. In this study, we model this problem as a dynamic transportation problem with transshipment considering the uncertain time-varying customers’ demand. To characterize the demand information, we first construct an ambiguity set of customers’ demand based in limited historical data and then develop a distributionally robust optimization-based (DRO) framework to optimize the transportation plan and related inventory level of crossdocks simultaneously. We also propose a general approach to overcome the computational challenges of DRO by transforming the original DRO into a second-order cone programming based on duality theory. Additionally, we introduce linear decision rules to adjust the optimization strategy based on the new observed demand, thus lead the model to handle the dynamic information flow in real time. In case study, all involved data are collected or derived from a real potassium fertilizer company located at Western China. The results show our model reduces the cost by 18.07% compared to stochastic model (sample average approximation), indicating a significant effectiveness of our model on the improvement of delivery efficiency and cost saving in real dynamic logistic systems. Also, we conclude the managerial insight that decision-makers should develop a comprehensive strategy, including improving communication to ensure order status updates, planning rationally to evenly distribute orders, and proactively allocating resources to meet operational demands.

Ten years of urea fertilization alter the pqqC‐harbouring community and increase soil inorganic phosphorus mobilization

AbstractThe bacterial communities that harbour the pyrroloquinoline quinone gene (pqqC‐harbouring bacteria communities) play a pivotal role in the mobilization of inorganic phosphorus (Pi). However, there is limited knowledge regarding the connection between soil pqqC‐harbouring bacterial communities and Pi fractions, as well as the factors that can regulate them, particularly under different fertilization strategies in the agricultural soil. High‐throughput sequencing was used to investigate the pqqC‐harbouring communities from the wheat (Triticum aestivum L.)–sweet potato (Ipomoea batatas L.) season in a 9‐year field experiment, including without fertilization (control), nitrogen (N) and potassium (K) fertilization (NK), NPK fertilization (NPK) and the combined application of chemical NPK and organic fertilizer (NPKM), and to explore their relationships with Pi fractions and their regulatory factors. Long‐term N fertilization and crop type substantially changed the community composition of pqqC‐harbouring bacteria but had no effect on their diversity. In two crop seasons, long‐term N fertilization significantly increased the content and proportion of moderately labile Pi (aluminium‐ and iron‐bound P) and available P (AP) and significantly decreased the proportion of recalcitrant Pi (calcium‐bound P) compared with the control. Specifically, AP increased by 79%–778%, Fe‐P by 64%–88%, and Al‐P by 71%–308%, while Ca‐P decreased by 10%–59%. N fertilization increased the relative abundance of Micromonospora, which was significantly positively correlated with moderately labile Pi and AP. Moreover, the relative abundance of some Streptomyces increased by 391% in the sweet potato season, and they were positively correlated with AP. Structural equation modelling revealed that the interplay between the pqqC‐harbouring community composition and Pi mobilization was mainly governed by pH, underscoring the role of pH in shaping the communities of Pi‐mobilizing microbes and their effect on Pi mobilization processes. This study emphasized how N fertilization and crops reshape Pi‐mobilizing microbial communities, which in turn affects Pi mobilization and P availability. Overall, these findings offer valuable insights into optimizing P cycles and availability through N fertilization strategies.

Response of Several Maize Cultivars to Potassium Fertilizer Levels

Response of Several Maize Cultivars to Potassium Fertilizer Levels

Mycorrhizal Effect on Potassium Availability, Potato Growth, and Yield in Relation to Potassium Fertilizer

Mycorrhizal Effect on Potassium Availability, Potato Growth, and Yield in Relation to Potassium Fertilizer

Эколого-агрохимическая оценка устойчивости серой лесной почвы к неблагоприятному воздействию и ее плодородие для выращивания сельскохозяйственных культур

The article presents research based on long-term field stationary experiments conducted at the agrotechnological experimental station of the UNIC "Agrotechnopark" to study the complex cultivation of gray forest soil of heavy loamy soil. The most favorable phosphate regime is soil with relatively high buffer properties, due not to the absorption of phosphorus by the solid phase, but its desorption. It was found that if the total acidification buffering capacity for pH intervals lies in the range of 9-11 mM–eq/100 g, then an average level of soil stability is achieved. In this case, the absorbed bases should be at least 20 mg-eq/100 g. It is not recommended to reduce the acidification buffering capacity to values less than 9 mM-eq/100 g. In long–term experiments with potash fertilizers, reliable increases in crop yields were established, which varied depending on the type of fertilizer and rotation in the range of 1.8 - 6.5 c/ha of grain units. On average, over 8 rotations, the increase was 5.0 c/ha of grain units. In the variant without fertilizers, the crop rotation productivity was about 24 c/ha of grain units. Keywords: GRAY FOREST SOIL, BUFFERING, NON-CHERNOZEM ZONE, PRODUCTIVITY, ORGANIC FERTILIZER, FERTILITY

Оптимизация технологических способов отработки калийных запасов при камерной системе разработки

The diverse demand for inorganic fertilizers has predetermined the intensification of potash mining, which is a raw material for their production. In this regard, it has become necessary to create risk management technologies for underground mining of potash deposits considering the spatial planning of mining operations while increasing the technological productivity of underground combine machines. The purpose of the study is to develop a technology to increase the technological productivity of mining set equipment to a level as close as possible to a combine at a minimum volume of preparatory work coupled with stopping operations. The subject of the study is the procedure for mining a designated mine field of potassium-magnesium deposit. Methods. The study applies a formal logistics approach based on an analysis of known facts and existing problems at a mining enterprise, the regulatory and technical documentation used and current scientific trends in this field. Based on the results of the analysis, conclusions and justifications were made. Then, a solution to the problem is proposed. Results. The study presents a modernized and improved potash mining method considering spatiotemporal changes. When planning the development of individual sections of a deposit, geological services carry out underground additional exploration to supplement geological knowledge of the area in question. Such work includes geological exploration, drilling wells from the face and perimeter of the mined-out void to select core for mechanical and chemical (furrow and core) testing, geophysical studies, etc. Discussion. The set purpose is achieved by preparing and developing the field with diagonal rooms. Prior to stopping operations, additional exploration drifts are carried out along the upper edge of the mined seam by paired faces along the entire length of the selected block. These mined out voids allow obtaining additional geological information about the section of the mine field being mined. Conclusion. A scheme for mining a selected field with a described sequence of stopping and cutting is proposed. The proposed scheme allows: to increase the technological productivity of mining set equipment to a level as close as possible to a heading-and-winning machine; to minimize the volume of preparatory work coupled with stopping operations. Resume. The proposed scheme for mining a selected section of a mine field with the described sequence of excavation allows us to increase the technological productivity of the mining complex to a level that is as close as possible to the technical productivity of a mining and shearer while simultaneously minimizing the volume of preparatory work, combining these works with the work of mining. Suggestions for practical applications and directions for future research. The research results can be useful in potash deposit mining by chevron cutting method considering spatial planning, safe mining operations and replenishment of geological information about the field.

Effect of potassic fertilization on yield of fodder sorghum-sudan grass hybrid and selection of extractants for determination of plant potassium availability

The current study was carried out to assess the effect of potassium (K) fertilization on K-uptake and yield of fodder sorghum-sudan grass hybrid and to choose extractant(s), delineating the K-availability for routine soil testing method. Hybrid sorghum-Sudan grasses were grown in three different soils (red, alluvial, and black) with 100, 50, and 0% recommended K-doses for five seasons. Seven extractants, namely, cold H2SO4, Mehlich-1, 0.1 N CH3COONa, 1 N CH3COONH4 (pH 7), 0.1 N BaCl2, and sodium tetraphenylborate (NaTPB) with 5 and 15 minutes of contact times, were evaluated for elucidating forage K-availability. Results have revealed that biomass yields from all soils were higher (p < 0.05) in K-100% than in K-0%; whereas NaTPB (5 minutes) and ammonium acetate were found as better extractants for the determination of forage K-availability.

Iron toxicity in lowland rice influenced by application of high potassic fertilizer with suitable cultivars enhanced productivity and climate resilience

Iron poisoning in low-land rice in India develops gradually and is primarily caused by anaerobic conditions in submerged rice fields. A high concentration of ferrous ions in the soil solution disrupts the potassium balance in rice plants, leading to adverse effects on crop growth. In the 2021–2022 period, an experiment was conducted in non-saline, iron-rich soil (pH–4.82, Fe–458.6 mg kg–1) to mitigate iron toxicity in rice cultivars through potassium nutrition. The experiment involved 4 potassium application doses (K-40, K-80, K-100 and K-120) and 32 rice cultivars, replicated twice using a split-plot design. Higher potassium doses led to increased tiller counts, but gradually decreased root length. Notably, cultivars like Kanchan, Indravati, Jagabandhu, Santepheap and Salibahan exhibited the lowest iron concentration in their grains compared to susceptible cultivars. Administering K-120 resulted in a yield increase of over 36.70 q ha-1. Grain yield increased with higher K dosage, although it did not affect total iron content. However, K doses did influence specific fractions of iron in the soil. Hence, potassium nutrition appears crucial in managing iron toxicity in inceptisols, especially when paired with cultivars tolerant to iron toxicity.

Effect of Different Level of Potassium and Sulfur Fertilizers on Growth and Yield of Onion (Allium cepa L.)

Effect of Different Level of Potassium and Sulfur Fertilizers on Growth and Yield of Onion (Allium cepa L.)

Soil Acidification Can Be Improved under Different Long-Term Fertilization Regimes in a Sweetpotato-Wheat Rotation System.

Soil acidification is a significant form of agricultural soil degradation, which is accelerated by irrational fertilizer application. Sweetpotato and wheat rotation has emerged as an important rotation system and an effective strategy to optimize nutrient cycling and enhance soil fertility in hilly areas, which is also a good option to improve soil acidification and raise soil quality. Studying the effects of different fertilization regimes on soil acidification provides crucial data for managing it effectively. An eight-year field experiment explored seven fertilizer treatments: without fertilization (CK), phosphorus (P) and potassium (K) fertilization (PK), nitrogen (N) and K fertilization (NK), NP fertilization (NP), NP with K chloride fertilization (NPK1), NP with K sulfate fertilization (NPK2), and NPK combined with organic fertilization (NPKM). This study focused on the soil acidity, buffering capacity, and related indicators. After eight years of continuous fertilization in the sweetpotato-wheat rotation, all the treatments accelerated the soil acidification. Notably, N fertilization reduced the soil pH by 1.30-1.84, whereas N-deficient soil showed minimal change. Organic fertilizer addition resulted in the slowest pH reduction among the N treatments. Both N-deficient (PK) and organic fertilizer addition (NPKM) significantly increased the soil cation exchange capacity (CEC) by 8.83% and 6.55%, respectively, compared to CK. Similar trends were observed for the soil-buffering capacity (pHBC). NPK2 increased the soil K+ content more effectively than NPK1. NPKM reduced the sodium and magnesium content compared to CK, with the highest magnesium content among the treatments at 1.60 cmol·kg-1. Regression tree analysis identified the N input and soil magnesium and calcium content as the primary factors influencing the pHBC changes. Structural equation modeling showed that the soil pH is mainly influenced by the soil ammonium N content and pHBC, with coefficients of -0.28 and 0.29, respectively. Changes in the soil pH in the sweetpotato-wheat rotation were primarily associated with the pHBC and N input, where the CEC content emerged as the main factor, modulated by magnesium and calcium. Long-term organic fertilization enhances the soil pHBC and CEC, slowing the magnesium reduction and mitigating soil acidification in agricultural settings.

A nutrient optimization method for hydroponic lettuce based on multi-strategy improved grey wolf optimizer algorithm

Hydroponic agriculture, as a modern agricultural technology, not only enables crops to better realize their growth potential but also frees them from the traditional agricultural constraints of land resources. Currently, the nutrient solutions for hydroponic crops are mostly prepared using generic formulas, lacking precise ratios based on the specific needs of different crop types and growth stages. It is of great significance to study the precise nutrient requirements of specific crops at different growth stages to enhance yield. To this end, a multi-strategy improved Grey Wolf Optimization algorithm is proposed in this paper to optimize the fertilizer model for hydroponic lettuce at different growth stages, providing more accurate nutrient requirements for hydroponic lettuce at different growth stages. Firstly, to solve the problems of the traditional GWO algorithm, such as insufficient exploration and the tendency to fall into local optima, non-linear functions, Symbiotic Organisms Search (SOS), and Opposition-Based Learning (OBL) were integrated into the GWO algorithm. Secondly, the objective was to minimize the residual function of the nitrogen, potassium, and calcium ternary fertilizer effect equation, the proposed algorithm was used to optimize the coefficients of the equation. Lastly, the optimal concentrations of NO3−, K+, and Ca2+ for each growth stage of lettuce were calculated based on the optimized fertilizer effect equations. The proposed algorithm was compared with five other excellent metaheuristic algorithms in optimizing fertilizer model coefficients. Experimental results indicate that the proposed algorithm outperforms the other algorithms used in the experiments. For the nutrient models of three growth stages, the proposed algorithm achieves improvements compared to the GWO algorithm, with R2 increasing by 0.73 %, 0.66 %, and 0.51 %, and RMSE decreasing by 8.53 %, 5.70 %, and 3.83 % respectively. This contributes to providing more accurate nutrient requirements for hydroponic lettuce.

Investigating the elemental composition of Egyptian glauconite sediments by applying BCR sequential extraction procedure and some single extractants

This study assesses the elemental composition of Egyptian glauconite sediments, focusing on potentially toxic elements (PTEs) and macronutrients. The primary aim is to evaluate the feasibility of utilizing these sediments as a natural source of potassium for agricultural purposes, besides conventional chemical fertilizers like potassium sulfate. To quantify elemental content, chemical analysis was employed across five distinct grain size fractions after grinding glauconite rock. The assessment included potassium, calcium, sodium, and PTE concentrations, utilizing potassium chloride (KCl) and ammonium acetate lactate (AL Solution) as single extractants, and the BCR extraction protocol, in addition to measuring the pseudo-total content of these elements. Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) facilitated a comparative analysis of elemental concentrations. Results indicate PTE concentrations within European Union regulations, with an absence of cadmium. Glauconite samples contain approximately 3–3.3% potassium by weight, alongside significant amounts of essential macronutrients (calcium, magnesium) and micronutrients (copper, nickel, zinc) crucial for agriculture. BCR sequential extraction protocol results closely align with or slightly surpass pseudo-total content results. Notably, the AL Solution demonstrates high efficiency compared to KCl or acetic acid in the first step of the BCR method. BCR sequential protocol provides valuable insights into various elemental forms and potential mobility. Overall, this study reveals that glauconite has the potential to serve as a promising alternative potassium fertilizer without causing adverse environmental impacts.

Bioenergetic assessment of the use of fertilizers for potatoes in the northern region of Kazakhstan

In field experiments, the high energy efficiency of the use of mineral fertilizers for potatoes on chestnut soils of northern Kazakhstan was revealed. The energy efficiency of the use of nitrogen, phosphorus and potash fertilizers has been established. The energy consumption of nitrogen fertilizers per 1 kg of increase in the yield of the main product, depending on the doses of fertilizers, ranged from 6223,3 MJ (efficiency = 2,2 units) to 15129,6 MJ (efficiency = 1,0 units). The energy content of 1 kg of phosphorous fertilizers used by increasing the yield of potato tubers (c) was estimated from 11712 MJ (efficiency = 1,9 units) to 18300 MJ (efficiency = 2,5 units), which indicates high energy efficiency. Energy costs varied in the range of 5130,5 MJ against the background of N45K45 and 7208,3 MJ against the best variant of N45P90K45. The energy efficiency from the use of potash fertilizers is estimated at 2,2 units for variants K45 and K90 against the background of N45P45. Energy costs are reduced by obtaining 1 c of potato tubers in more efficient variants in terms of the energy efficiency of the fertilizers used. Knowing the energy costs (Ao, MJ) for growing crops and the energy content (Vf0, MJ/ha) in the yield of products, it is possible to conduct a bioenergetic assessment of the effectiveness of crop cultivation in the practice of applying fertilizers. The purpose of the research is to identify the bioenergetic efficiency of the use of mineral fertilizers for potatoes on chestnut soil in the conditions of the Northern region of Kazakhstan.

Effects of large-scale restoration on understory plant communities in an industrial landscape

Starting in the mid 1970’s, researchers, industry leaders, and residents collaborated on one of the world’s largest regreening programs in the industrial region of Sudbury, Canada. The Sudbury Regreening Recipe included the application of crushed dolomitic limestone, nitrogen–phosphorus–potassium fertilizers, grass–legume seed mixtures across 8200 ha, and subsequent tree planting across 25 000 ha of acidic metal-contaminated land. The current study evaluated shifts in understory vegetation diversity and soil geochemistry on a chronosequence of sites treated the same way between 1982 and 2012. Fifty-six plant species were identified across the 24 sites, only four of which were planted in the initial remediation effort. Key factors influencing plant community composition and diversity were related to shifts in soil properties over time: bulk density, LFH layer depth, and mineral soil horizon pH. Plant communities differed with stand age and rocky sites had significantly different plant communities and lower canopy cover than less rocky sites. Mineral soil horizon pH increased with age, reflecting the movement of applied dolomite in soil. Despite high concentrations of total copper and nickel in soil, plant succession patterns were generally similar to those in naturally recovering forests demonstrating the overall success of the restoration program.

CONTENT AND EXPORT OF N, P, K AND SI WITH MAIZE BIOMASS DEPENDING ON THE FERTILIZATION ON ALLUVIAL-MEADOW SOIL

The aim of the study in a pot experiment on Alluvial-meadow soil (Fluvisol, FAO) was to evaluate the effect of different rates and combinations of nitrogen, phosphorus, potassium and silicon fertilizers on the growth of maize (Zea mays L.) an early hybrid Р-8834 from group 310 FAO “Syngenta”. The experiment included 16 variants of fertilization in 3 replications. Data were obtained on the yield of fresh and absolutely dry biomass of maize plants and the content of N, P, K and Si in the dry biomass was assessed. It was found that the concentrations and the export of the studied macroelements with the biomass were significantly influenced by the fertilization applied. Nitrogen export was the highest in the N200, N300 and N400 rate treatments, and in comparison with the export of the other investigated elements. The export of N, P, K, and Si with maize dry biomass corresponded to a significant extent the contents of the macroelements in it. With increasing fertilization rates, not only the content, but also the export of nitrogen, phosphorus, and silicon increased. Regarding the potassium, this tendency was expressed to a less extent.

Effects of Agricultural Potassium Fertilizer Application on Soil Carbon Cycle

This review examines the impact and regulatory mechanisms of potassium fertilizer on the soil carbon cycle, discussing how potassium fertilizer affects soil carbon storage and flow through various pathways. As a vital agricultural nutrient, potassium not only plays a crucial role in crop growth but also influences several aspects of the soil carbon cycle, including carbon sequestration, microbial activity, soil respiration, and the structure and enzymatic activities of the soil. The article begins by introducing the importance of the soil carbon cycle and the application of potassium in agriculture, followed by an analysis of how potassium fertilizer promotes soil organic carbon storage, including increasing the amount of plant residue returned to the soil. It then discusses the impact of potassium fertilizer on the structure and function of soil microbial communities, which play a key role in the soil carbon cycle. The article also explores the influence of potassium fertilizer on soil respiration, including its regulatory effects on microbial respiration and root respiration, and how potassium improves soil structure to affect soil respiration. Additionally, the impact of potassium fertilizer on the activity of enzymes related to carbon cycling is discussed in detail, as these enzymes play a central role in the decomposition of organic matter and nutrient cycling. Finally, the article summarizes the potential role of potassium fertilizer in improving soil health, enhancing carbon sequestration capacity, and addressing climate change, calling for more research to understand the mechanisms of potassium fertilizer and to provide a scientific basis for sustainable soil management strategies.

Straw Return Substituting Potassium Fertilizer Increases Crop Yield, Efficiency, and Quality in Maize-Wheat Rotation System

The application of potassium fertilizer application and straw return are effective agronomic measures for increasing crop productivity; however, information on how straw return—when substituting potassium fertilizer—affects crop yield, efficiency, and quality in dryland remains limited. In this study, an experiment on a dryland summer maize and winter wheat rotation system was initiated in 2007. This study included four treatments: CK (no fertilizer and no straw return), NP (nitrogen and phosphorus fertilizer application without straw return), NPK (nitrogen, phosphorus, and potassium fertilizer application without straw return), and NPS (NP treatment with straw return, substituting potassium fertilizer as used in the NPK treatment). These treatments were employed to assess grain yield and fertilizer agronomic efficiency in 2015–2020. Additionally, we evaluated the content of nitrogen (N), phosphorus (P), and potassium (K), as well as the protein content and protein yield in maize and wheat grains and the protein components in wheat grains in 2019–2020. The results showed that compared to the CK treatment, NP, NPK, and NPS treatments not only significantly increased the yield, protein yield, and fertilizer agronomic efficiency in both maize and wheat but also increased the content of protein and protein components in wheat grains. Compared to the NP treatment, the NPK treatment significantly increased the contents of N, K, globulin, and gluten in wheat grains by 5.11%, 21.59%, 10.06%, and 15.14%. Compared to NPK treatment, NPS treatment significantly increased the average yield of summer maize by 21.33% and 20.91%, respectively, as well as the annual yield by 9.99% and 13.59%, the N fertilizer agronomic efficiency of summer maize by 132.47%, and the annual N and P fertilizer agronomic efficiency by 42.83% and 64.36%, over the five-year period. The NPS treatment also significantly increased the summer maize protein yield and annual protein yield by 10.43% and 23.08%, as well as the content of protein components, the protein content, and P content in wheat grains by 4.93–13.58%, 7.81%, and 28.89%, respectively. In conclusion, NPS treatment can not only enhance crop yield, protein yield, and fertilizer agronomic efficiency in summer maize annually but also has the advantage of promoting wheat quality. NPS is an efficient strategy to improve crop yield, efficiency, and quality in a dryland maize–wheat rotation system.