Potassium Fertilizer Rates Research Articles

Potassium Fertilizer Application Rates for Fertigated Edamame Grown on Low-K Soils

Edamame, a legume consumed fresh as a vegetable, is highly nutritious, particularly protein-rich, and holds significant economic value. However, its cultivation faces challenges, especially on dry land, due to water scarcity and limited nutrient availability, particularly potassium (K). This study, which investigated the impact of potassium fertilization rate on edamame cultivation, underscores the need for further research. The study utilized a single factor, potassium fertilization rate, arranged in a completely randomized block design. Potassium rates consist of 0% X, 50% X, 100% X, 150% X, and 200% X, where X represents the recommended potassium fertilization rate according to the dry soil test device (DSTD) guidelines. Each treatment was replicated five times. Data were analyzed using ANOVA at a 5% significance level, and any significant effects were further examined using orthogonal polynomial and regression analysis. The results indicated that potassium fertilizer rates did not significantly affect edamame height, pod weight per plot, and marketable yield. However, the study identified the optimal potassium fertilizer rate, which was between 83%X and 119%X, equivalent to 83–119 kg.ha⁻¹ of KCl (50–72 kg.ha⁻¹ of K₂O). This range positively increased total branch yield, productive branches, number of flowers, pod weight per plant, number of pods per plant, and plant dry weight, producing a quadratic response pattern. The study recommends further research to optimize potassium fertilizer doses based on DSTD recommendations, particularly at a low K nutrient status, to maximize marketable yields through fertigation.

Effect of different rates of slow-release potassium fertilizers on growth and fruiting of banana var. Grand Nain plants

Effect of different rates of slow-release potassium fertilizers on growth and fruiting of banana var. Grand Nain plants

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.

Potassium fertilizer promotes the thin-shelled Tartary buckwheat yield by delaying senescence and promoting grain filling.

The application rate of potassium fertilizer is closely related to the yield of crops. Thin-shelled Tartary buckwheat is a new variety of Tartary buckwheat with the advantages of thin shell and easy shelling. However, little is known about application rate of potassium fertilizer on the yield formation of thin-shelled Tartary buckwheat. This study aimed to clarify the effect of potassium fertilizer on the growth and yield of thin-shelled Tartary buckwheat. A field experiment to investigate the characteristics was conducted across two years using thin-shelled Tartary buckwheat (Miku 18) with four potassium fertilizer applications including 0 (no potassium fertilizer, CK), 15 (low-concentration potassium fertilizer, LK), 30 (medium-concentration potassium fertilizer, MK), and 45 kg·ha-1 (high-concentration potassium fertilizer, HK). The maximum and average grain filling rates; starch synthase activity; superoxide dismutase and peroxidase activities in leaves; root morphological indices and activities; available nitrogen, phosphorus, and organic matter content in rhizosphere soil; urease and alkaline phosphatase activities in rhizosphere soil; plant height, main stem node number, main stem branch number, leaf number; grain number per plant, grain weight per plant, and 100-grain weight increased first and then decreased with the increase in potassium fertilizer application rate and reached the maximum at MK treatment. The content of malondialdehyde was significantly lower in MK treatment than in other three treatments. The yields of thin-shelled Tartary buckwheat treated with LK, MK, and HK were 1.22, 1.37, and 1.07 times that of CK, respectively. In summary, an appropriate potassium fertilizer treatment (30kg·ha-1) can delay the senescence, promote the grain filling, and increase the grain weight and final yield of thin-shelled Tartary buckwheat. This treatment is recommended to be used in production to achieve high-yield cultivation of thin-shelled Tartary buckwheat.

Improving Growth and Productivity of Safflower (Carthamus tinctorius L.) Plant by Utilizing L-Tryptophan and Phenylalanine Acids under Different Potassium Fertilizer Rate

Improving Growth and Productivity of Safflower (Carthamus tinctorius L.) Plant by Utilizing L-Tryptophan and Phenylalanine Acids under Different Potassium Fertilizer Rate

Yield gap analysis and the relative importance of factors explaining yield variability in paddy fields

Closing the yield gap of strategic crops can facilitate achieving sustainable solutions to alleviate hunger, ensure food security, and enhance nutrition. This study aimed to quantify factors affecting rice yield gap in northern Iran using experimental and survey data on yields and management practices. The CERES-Rice model, calibrated with data (2011, 2016, 2019) from two regions, was used to estimate potential yield (Yp) of different rice cultivars. Yield gaps were calculated as the difference between economic yield potential and the average yield attained by farmers. The calibration process showed that cultivar coefficients varied across rice varieties. The simulated yields (2012–2021) showed that the mean potential yields were 13362 kg ha−1 and 8818 kg ha−1 for the late and early-maturing cultivars, respectively. High temperature was the most important yield defining factor across the rice growing areas. The yield gap was 3751 kg ha−1 and 2830 kg ha−1 in the late- and early-maturing cultivars, respectively. Nitrogen fertilizer rate, number of fertilizer applications, phosphorus fertilizer rate, transplanting date, potassium fertilizer rate, and seedling age were the top factors influencing the yield gap. Among the management factors, rice fertilizer management explained about 65% of the yield variability. Together, transplanting date and seedling age explained 15.3% of the variability in rice production, while pest, disease, and weed damage accounted for 9.6%. Breaking down the yield gap into affecting factors allows growers to improve the production system by providing the best crop management according to their facilities and capabilities. This approach is essential for optimizing agricultural productivity and achieving sustainable food production goals.

Exploring the influence of supplemental potassium fertilizer types and rates on garlic quality and yield

Exploring the influence of supplemental potassium fertilizer types and rates on garlic quality and yield

Application of fulvic acid and potassium fertilization to reduce the harmful effect of salt water stress on growth, productivity and nutritional status of tomato plants

Water is a key resource for sustainable agricultural development in Egypt. The scarcity of fresh water resources in Egypt has led to the use of salt water for irrigation. Therefore, the aim of the research was to study the effect of potassium fertilization and spraying with fulvic acid on tomato plants irrigated with salt water and grown in sandy soil during two successive growing seasons. Different rates of the potassium fertilization combined with different concentrations of fulvic acid foliar application. The rates of K fertilization were 150, 200 and 300 Kg K2O per hectare of the recommended fertilizer unit (300 kg K2O ha-1). While, the concentrations of fulvic acid were 500, 1000 and 2000 mgl-1. Increasing the spraying concentration of fulvic acid from 500 to 2000 ppm resulted in a significant improvement in the parameters of growth, quantity and quality yield of tomato plants with an increase in potassium fertilization rates from 150 to 300 K2O kg ha-1with the use of saline irrigation water. Increasing the concentration of fulvic acid spraying led to the uptake of nitrogen, phosphorus and potassium in tomato leaves increased with an increase in potassium fertilization rates.Therefore, it can be said that spraying fulvic acid with the use of potassium fertilization is one of the successful solutions in reducing the effect of irrigation with salt water on the growth and yield of tomato plants.

Estimating thresholds of nitrogen, phosphorus and potassium fertilizer rates for rice cropping systems in China.

Determining the fertilization rate plays a pivotal role in agronomic practices as they directly impact yield targets, soil fertility, and environmental risks. In this study, we proposed a method that utilizes allowed ranges of partial nutrient balance and yield to estimate the threshold of nitrogen (N), phosphorus (P), and potassium (K) fertilizer applied to rice (Oryza sativa L.) fields in China. Based on a dataset of 6792 observations from rice fields, we determined the minimum and maximum rates of N, P and K suggested for single (mono-season rice), middle (summer-season rice rotated with winter-season upland crop), early and late (double-season rice cropping system) rice, ranging between 114-146 and 220-292 kg N ha-1 per season, 56-74 and 112-149 kg P2O5 ha-1 per season, and 170-230 and 329-347 kg K2O ha-1 per season, respectively. These values serve as the lower and upper fertilization thresholds, guiding yield goals and environmental protection. Furthermore, if rice straw is returned to fields, the demand for K fertilizer can theoretically decrease by 183 kg K2O ha-1, with corresponding decreases of 50 kg N ha-1 and 26 kg P2O5 ha-1, respectively. A recommended fertilization approach, excluding returned straw nutrients from the upper fertilization thresholds, suggested average application rates of 194 kg N ha-1, 105 kg P2O5 ha-1, and 157 kg K2O ha-1, which align well with the nutrient requirements of rice. Additionally, substituting organic N for chemical N is an effective approach to conserve chemical fertilizer N, potentially reducing chemical N usage by 20%-40%. Utilizing slow-release N is also a favorable option to enhance N use efficiency and optimize N balance. This study offers valuable insights into the development of fertilization restriction indicators, aiming to achieve a delicate balance between environmental impact and agricultural productivity through the adoption of balanced fertilization rates and utilization of organic residues.

The Molecular Mechanism of Potassium Absorption, Transport, and Utilization in Rice

Potassium is essential for plant growth and development and stress adaptation. The maintenance of potassium homeostasis involves a series of potassium channels and transporters, which promote the movement of potassium ions (K+) across cell membranes and exhibit complex expression patterns and regulatory mechanisms. Rice is a major food crop in China. The low utilization rate of potassium fertilizer limits the yield and quality of rice. Elucidating the molecular mechanisms of potassium absorption, transport, and utilization is critical in improving potassium utilization efficiency in rice. Although some K+ transporter genes have been identified from rice, research on the regulatory network is still in its infancy. Therefore, this review summarizes the relevant information on K+ channels and transporters in rice, covering the absorption of K+ in the roots, transport to the shoots, the regulation pathways, the relationship between K+ and the salt tolerance of rice, and the synergistic regulation of potassium, nitrogen, and phosphorus signals. The related research on rice potassium nutrition has been comprehensively reviewed, the existing research foundation and the bottleneck problems to be solved in this field have been clarified, and the follow-up key research directions have been pointed out to provide a theoretical framework for the cultivation of potassium-efficient rice.

Fertilizer doses and mulching effect to mitigate soil salinity and maximize yield of watermelon (Citrullus lanatus L.) in coastal region of Bangladesh

An experiment was conducted in the rabi season at Patuakhali, Bangladesh to verify the effect of different mulching materials for watermelon production under farmers field condition. The aim of this research was to test the possibility of salinity damage can be reduced by elevating potassium (K) fertilization rate on watermelon yield and nutrient uptake under salt stress condition. Four different fertilizer doses T1 = Soil Test Based (STB), T2 = STB + 50% K, T3 = Integrated Plant Nutrients System (IPNS) approach with 5 tonha-1 cowdung (CD) + 50% K and T4 = Farmers practices with many materials usedP1 = Silver color polythene mulch, P2 = Straw mulch, P3 = No mulch combination. Twenty days old seedling were used in farmers’ field. Other nutrients were also applied following STB method. Fertilizer used as the rates of N117P30K30S25 (T1), N117P30K37S25 (T2), N92P22.5K45S25 with 5 tonha-1cowdung (T3) and N100P40K35S30 (T4). All the plant growth, yield and quality characters were superior in T3 with silver polythene (31.96 tonha-1) while plants without mulch and STB method resulted poor growth and yield of 24.31 tonha-1. The higher rates of K contributed to 7- 27% increased yield over only STB dose for Patuakhali which implies the necessity of higher dose of K in salt affected soil in strengthening yield. With economic point of view, T3 (IPNS with 5 ton/ha cowdung + 50% K and silver polythene mulch) seedling reported the highest net return of 375780 Bd TK and found more economical with highest cost benefit ratio.

Influence of production situation on the incidence of brown spot of rice (Oryza sativa) caused by Bipolaris oryzae in the Philippines

AbstractBrown spot, caused by Bipolaris oryzae, is becoming more prevalent and important in the Philippines but risk assessment is limited. Surveys of 2186 farmers' fields were conducted in the major rice‐growing areas in the country from 2015 to 2018 to analyse the components of production situation (PS) that contribute to the area under the progress curve of brown spot incidence (aBS). Based on lasso regression, the components of PS that influence aBS, in decreasing order, are ecosystem (irrigated vs. rainfed), crop establishment method (direct seeding vs. transplanting), variety type (hybrid vs. inbred), rate of phosphorus fertilizer, rate of potassium fertilizer, application of organic fertilizer (with vs. without organic fertilizer) and frequency of fungicide application. Pairwise comparisons showed that aBS is positively associated with direct‐seeded rice, rainfed ecosystem, hybrid rice, moderate to high P and K rates and spraying of fungicide. Correspondence analysis and chi‐squared tests showed that the class with highest aBS is closely associated with the production situation characterized by rainfed ecosystem, direct‐seeded rice, fungicide application, moderate nitrogen and moderate to high phosphorus and potassium rates; and weather pattern (temperature, relative humidity, solar radiation, rainfall and wind speed) that occurs during the wet season. These results confirm previous studies showing that increased adoption of water‐saving technologies and direct seeding for adaptation and mitigation to climate change and reduction of agricultural labour, will most probably favour brown spot. Strategies to manage the disease under these production situations should be implemented in government programmes and considered in future research agendas.

Effects of Source and Rates of Potassium Fertilizer on Yield Traits and Potassium Use Efficiency of Potato in a Kenyan Ferralsol

Aims: Potassium (K) is one of the nutrient elements taken up in large amounts by potatoes, yet there is little research output on K fertilization of the crop in Kenya, due to the assumption that its natural soil reserves are sufficient for the production of most crops. The study objective was to determine the influence of two K sources (muriate of potash – KCL and sulphate of potash – K2SO4) on K use efficiency and tuber yield components of potatoes in one agro-ecological zone of Kenya.
 Place and Duration of Study: The experimental site was the University of Eldoret farm in Kenya, located at latitude 0o574942’ N and longitude 35o300772’ E, during the middle - second rains season (S1) and middle rains season (S2) of 2020 and 2021 respectively.
 Methodology: Treatments were: 0 kg K ha-1 (control), 60,120,180 and 240 kg K ha-1 in S1 and 0, 30, 60, 90, 120 and 180 kg K ha-1 in S2, supplied in the form of KCL and K2SO4. Treatments were laid in a Randomized Complete Block Design in 2x5 and 2x6 factorial arrangements in S1 and S2 respectively. The potato variety planted was Destiny. Data collected included: Agronomic efficiency of K (AEK,), total tuber yield, two categories of seed yield (Size 1 tubers with diameters of 28- 45 mm; Size 2 tubers with 46 - 60mm diameter), total seed yield and ware yield (tubers with diameters over 60mm).
 Results: During the drier S1, the application of 120 kg K ha-1 in the form of K2SO4 significantly (P < .001) increased the yield of size 1 tubers, total seed yield and total tuber yield. The total tuber yield increment from this K rate was only 12.6 % of the varietal potential yield, and its AEK was 0.042 tonnes of tubers kg-1 K. Therefore its application may not be economically viable. During the moisture-sufficient S2, all K fertilizer treatments in the form of KCl and 90 kg K ha-1 in the form of K2SO4, contributed a yield increase of 58.1 - 68.6% and slightly exceeded varietal yield potential. Additionally, 30 kg K ha-1 of KCL gave the highest AEK of 0.5 tonnes of tubers kg-1 K and consistently enhanced the yield of all potato sizes, except size 1.
 Conclusion: Under similar ecological conditions as S2, potato farmers can achieve the highest AEK and potential tuber yield with the application of 30 kg K ha-1 of KCL. However, more trials on K nutrition in potatoes need to be done in diverse environments.

Effect of Site-Specific Application of N and K Fertilizers on Cashew Growth and Yield in Ochaja, Kogi State, Nigeria

An experiment was conducted at the Ochaja Substation of the Cocoa Research Institute in Ibadan, Nigeria. Ochaja is located in the guina savanna zone of Nigeria. Plantation soil nutrient requirements were determined prior to applying the required fertilizers. The soil was deficient in nitrogen (N) and potassium (K), with values ​​of 0.41 g/kg soil and 0.012 cmol/kg soil, respectively, at depths 0–40 cm. This value was used to calculate cashew fertilization rates of 54 kg N/ha and 84 kg K2O/ha. Based on these values, four treatment combinations of two rates of nitrogen fertilizer and two rates of potassium fertilizer were formed and applied to young cashew trees on the field. Nitrogen fertilizer was applied at 0 and 54 kg N/ha while the Potassium was applied at 0 and 84 kg K/ha. Treatments were placed in a Randomized Complete Block Design (RCBD) with three replications, Cashew growth, nut yield and soil nutrient characteristics were measured. The first dose was applied in June while the second dose was applied in September of 2019 and 2020. Application of N fertilizer had a significant lowering effect on soil pH at both soil depths compared to the control and compared to N and K fertilizers applied together. Similarly, application of potassium-based fertilizer, with or without nitrogen fertilizer, slightly increased soil pH by 5.4%. Soil N had a significant effect (P < 0.05). Total N ranged from 0.5 g/kg to 0.7 g/kg soil for fertilizer treatments. N and K fertilizers did not significantly improve available soil phosphorus (P) across fertilization treatments. Exchangeable K in soil followed a similar trend with available P in different treatments. Yield of cashew nuts (280kg) improved significantly (P < 0.05) under application of sole nitrogen fertilizer and the control.

The role of gamma radiation on the productivity of sesame plants and potassium efficiency under different rates of potassium fertilization

The role of gamma radiation on the productivity of sesame plants and potassium efficiency under different rates of potassium fertilization

Relationship between Seed Properties and Outcome Components for Selection Criteria of Corn (Zea Mays L.) Products at Various Dosages of Popostium Fertilizer

This research was conducted to determine the relationship between seed developmental characteristics and yield components in a population of maize (Zea mays L.) grown at different potassium fertilizer rates. The information could be utilized as alternative selection criteria for maize genotypes with high-yielding potential. This research was conducted at the Experimental field of the Horticulture Seed Agency, Pekanbaru. Seven maize genotypes with four potassium fertilizer rates were grown in a 350 cm x 200 cm experimental plot with three replications. The genotypes used were Bisi 228. Pertiwi 3. Bisi 2. Decoral, Bisi 18. Betras 4. and Srikandi. Potassium fertilizer rates included 30 kg, 50 kg, 70 kg, and 90 kg per ha, respectively. Traits observed were plant height, tesseling flowering date, silking date, seed dry accumulation rate, effective seed filling period, cob length, cob weight, number of seed rows, number of seeds per cob, seed weight per cob, the weight of 100 seeds and seed yield per m2. Analysis of variance was performed to the data using SAS and further tested by honesty significant difference at 5% level. Variance component, heritability, genetic correlation coefficient, and selection response were calculated for all characters and effective seed filling duration. The results indicated that the genetic variance component was significant for all characters except for the dry matter accumulation rate. All characters' heritability values were quite high except for effective seed-filling duration and the number of seeds per cob. Phenotypic correlation coefficients were positively significant between seed yield per m2 and plant height, seed development rate, cob length, ear weight, number of seeds per ear, seed weight per ear, and weight of 100 seeds. The genetic correlations was significant between seed yield per m2 and plant height, seed development rate, number of seeds per ear, and seed weight per ear. All characters' direct selection response value is higher than the indirect selection response value.

Evaluation of Competitive Indices Between Caraway and Garlic as Affected by Intercropping System and Potassium Fertilization Level

During the winters of 2020/2021 and 2021/2022, an experiment was done on a private farm in Taha El-Marg Village, Diarb Negm District, Al Sharqia Governorate, Egypt. The purpose of these studies was to examine the impact of intercropping systems using caraway and garlic at varying row ratios (single crop of each as control, 1:2, 2:1, and 2: 2, respectively) and potassium rates (0.0, 25, 50, and 75 kg K2O/feddan) on competitive indices between the two crops. Plots consisted in the intercropping systems and the subplots were constituted by the potassium fertilization rates. Alternating two rows of caraway with one row of garlic significantly increased land equivalent ratio (LER), area× time equivalent ratio (ATER) and land utilization efficiency (LUE%) compared to the other intercropping systems. Under the highest potassium fertilization level, the highest values of LER (1.17 and 1.10), ATER (1.09 and 1.04) and LUE% (112.82 and 107.00%) were achieved. In general applied intercropping systems (1:2 or 2: 2 systems) were more efficient than sole cropping and other one under study when combined with potassium fertilization rate at 75 kg K2O/feddan, in most cases. Both competitive ratio (CR) and Aggressivity (A) estimation showed that caraway was dominant while garlic was dominated.

Effects of Nitrogen and Potassium on Yield and Quality Of Potato (Solanum Tuberosum L.) Cultivars

Effects of nitrogen (N) and potassium (K) fertilization rates on the yield and quality of two potato cultivars, Asterix and Courage were conducted. The treatment combination of N2K2 (N2: 140 kg ha−1 and K2: 152 kg ha−1) had the highest total yield (31.38 and 22.51 t ha-1), marketable tuber yield (29.08 and 20.49 t ha-1) and chips potato yield (36.63 and 36.96%) of the 18 treatment combinations for Asterix and Courage cultivar, respectively. The treatment combination of N2K2 had also the highest specific gravity (1.07 and 1.17 gcm-3), dry matter (22.65 and 22.77%), firmness (45.13 and 42.92 N), and lowest total soluble solid (4.30 and 4.23 oBrix) in both the cultivars, whereas the colour of the chips revealed the least crispness (0.15 and 0.17 N). In order to enhance potato processing quality without reducing production, a lower N and higher K treatment combination may be employed. Bangladesh J. Bot. 52(2): 267-275, 2023 (June)

Effects of potassium fertilizer rates on growth, tuber yield and quality of sweet potato (Ipomea batatas L) in Ogbomoso, Southwest Nigeria

Sweet potato (Ipomoea batatas L) is an important dicotyledonous tuberous staple crop of the Convolvulaceae family. It is valued for its tubers which are either boiled, fried, baked or roasted for human consumption or boiled and fed to livestock as a source of energy. However, the cultivation of sweet potato is constrained by low soil fertility, particularly inadequate potassium, which plays a pivotal role in the growth and tuber development of sweet potato. Therefore, the effects of potassium fertilizer rates on the growth, tuber yield and quality of sweet potato were determined at the Teaching and Research Farm, Ladoke Akintola University of Technology, Ogbomoso during 2022 major cropping season. The treatments were; 0 (control), 60, 90, 120, 150 and 180 kg K2O/ha laid out in randomized complete block design replicated three times. Data collected on length of primary vines, number of leaves, fresh shoot biomass, number of tubers, fresh tuber yield and nutritional contents of the tubers were subjected to analysis of variance and treatment means separated with least significance difference (LSD) at 5% probability level. The application of K fertilizer had significant influence on the performance of sweet potato. At 14 weeks after planting (WAP), plants treated with 180 kg K2O/ha produced the longest mean vine length (p = 0.043, 184.93 cm), highest number of leaves (p = 0.003, 217), highest fresh shoot biomass (p = 0.015, 11.83 t/ha), number of tubers (p = 0.037, 68) and fresh tuber yield (p = 0.0004, 22 t/ha). In contrast, plants that received no fertilizer, had the shortest vine length (133.67 cm), the least fresh shoot biomass (7.1 t/ha) and tuber yield (12.7 t/ha). The least number of leaves (136) was observed with the application of 60 kg K2O/ha while 90 kg K2O/ha produced the least number of tubers (46). The potassium content of sweet potato tuber was significantly influenced by K fertilizer rates, whereas the phosphorus content was unaffected. The highest contents of phosphorus (p = 0.967, 0.10%) and potassium (p = 0.038, 1.26%) were recorded in tubers that received 150 kg K2O/ha and 180 kg K2O/ha, respectively. The carotenoid, carbohydrate, and protein contents of sweet potato tuber decreased as the potassium rates increased. Conversely, the crude fiber content increased (p = 0.044) as the potassium rate increased. In conclusion, application of 180 kg K2O/ha improved the performance of sweet potato better than the other rates in the study area. However, it seems that the maximum yield potential of sweet potato in the study area had not been attained. Therefore, further research with higher than 180 kg K2O/ha may be required to identify the optimal level for cultivating sweet potatoes.

Response of Maize (Zea mays L.) to Blend (Nitrogen, Phosphorus, Sulfur, Boron) and Potassium Fertilizers Rates at Boloso Sore Woreda, Ethiopia

Background: The declining soil fertility is a severe bottleneck for crop production in Ethiopia. The application of inorganic fertilizer helps to correct a site-specific nutrient deficiency. Methods: The research was conducted at Achura kebele Farmers Training Center (FTC) from December 2020 to July 2021. Soil samples and crop data were collected and analyzed by standard procedures. Result: The soil reaction revealed that the soil was moderately acidic (pH=5.68) and low in organic carbon, total nitrogen, available phosphorus, potassium, sulfur and boron. The result of this study indicated that the growth and yield of maize were significantly (P less than 0.05) affected by the combined effect of both blended (nitrogen, phosphorus, sulfur, boron) and potassium fertilizer rates. The highest grain yield (7200.9 kg ha-1) was found from NPSB, 200 kg ha-1 + K, 50 kg ha-1and the lowest was recorded from control.