NPK Fertilizer Research Articles

Optimization of Soil Temperature Dynamics under Different Irrigation Schedules, Tillage Methods, and NPK Fertilizer Application Rates

Optimization of Soil Temperature Dynamics under Different Irrigation Schedules, Tillage Methods, and NPK Fertilizer Application Rates

Comparing the Growth Rates of Ipomoea aquatica Using Washed Rice Water From Different Rice Varieties

Numerous agricultural sectors rely on chemical fertiliser to accelerate crop development, as demand continues to expand each year. Synthetic fertilisers may leak into groundwater, increasing its toxicity and resulting in water contamination. Alternatives such as washed rice water may be utilised to mitigate the environmental impact of chemicals. This research aims to assess the effects of washed rice water on the growth rate of Ipomoea aquatica. Three types of rice water were used in this study: washed white rice water, washed brown rice water, and washed sticky rice water. Two of the rice water served as the control and each was treated with distilled water and NPK fertiliser. Significant values were determined using Analysis of Variance (ANOVA) and post-hoc tests for multiple comparisons. Resultantly, washed white rice water demonstrated the most significant effect in increasing the growth of the plant height, length of root, number of leaves, circumference of the stem and suitability of soil pH. Alternative methods such as washed white rice water could be employed to reduce the cost of agricultural operations to protect the environment from further degradation.

Secondary and Multi-micronutrient (S, B & Zn) Doses on Yield and Residual Effect on Rice-groundnut Cropping System in Alfisols of Odisha, India

Orissa is the fourth largest state in India covering an area of 15.57 m ha out of which the net sown area is 6.13 m ha. Out of 8 broad soil groups found in the state, red and laterite groups of soil occupy more than 75% of total cultivable area. Low productivity of crops in red and laterite soils are associated with deficiency of Ca, Mg, S, B and Mo (Mitra and Sahu, 1988). The DTPA extractable Zn also indicates that red and laterite soils of Orissa is deficient in available Zn and respondent to Zn application to rice crop (Anonymous, 2002; Mandal et al., 2009). Next to Zn, the deficiency of B is wide spread in many districts of the state as well as contrary (Sharma et al., 2006). Rice-Groundnut is the most prevailing cropping pattern in red and Lateritic soils of Orissa. In spite of recommended dose of NPK fertilizer, the farmers get low yield. A field experiments were carried out with rice-groundnut cropping systems in two successive cropping seasons each, to study the effect of S, B and Zn on grain yield, nutrient uptake and their accumulation. The experimental design included ten treatments, T1: control, T2 : S 40 kg/ha, T3 : B 1 kg/ha, T4 : Zn 5 kg/ha, T5 : FYM 5 t/ha, T6 : S+B, T7 : S+Zn, T8 : B+Zn, T9 : S+B+Zn and T10 : S+B+Zn+FYM replicated thrice in randomized block design. Integrated use of S + B + Zn with FYM was the ideal combination for rice-groundnut cropping system as it was more sustainable, recorded the highest yield and SYI value along with higher accumulation and uptake of nutrients. The results revealed that red and lateritic soils are poor in S and B need integrated use of S, B and Zn along with recommended dose of NPK for getting synergistic and best effect in rice-groundnut cropping system.

Sustainable Wheat Cultivation in Sandy Soils: Impact of Organic and Biofertilizer Use on Soil Health and Crop Yield

Sandy soils are widespread globally and are increasingly utilized to meet the demands of a growing population and urbanization for food, fiber, energy, and other essential services. However, their poor water and nutrient retention makes crop cultivation challenging. This study evaluated the effects of integrating compost and plant growth-promoting rhizobacteria (PGPR; Azospirillum brasilense SWERI 111 and Azotobacter chroococcum OR512393) on wheat (Triticum aestivum L. var. Misr 1) grown in sandy soil under varying levels of recommended NPK (50%, 75%, and 100%) fertilization. Conducted over two growing seasons, the experiment aimed to assess soil health, nutrient uptake, microbial activity, and plant productivity in response to compost and PGPR treatments. The results demonstrated that combining compost and PGPR significantly improved soil chemical properties, such as reducing soil pH, electrical conductivity (ECe), and sodium adsorption ratio (SAR), while enhancing soil organic matter (SOM). Additionally, compost and PGPR improved soil nutrient content (N, P, K) and boosted the total bacterial and fungal counts. The combined treatment also increased urease and phosphatase enzyme activities, contributing to enhanced nutrient availability. Notably, plant productivity was enhanced with compost and PGPR, reflected by increased chlorophyll and reduced proline content, along with improved grain and straw yields. Overall, the results underscore the potential of compost and PGPR as effective, sustainable soil amendments to support wheat growth under varying NPK levels.

EVALUATION OF SESAME (SESAMUM INDICUM L.) AS AFFECTED BY NPK FERTILIZER RATES AND COWPEA [VIGNA UNGUICULATA (L.) WALP.] SOWING DATES IN SESAME AND COWPEA INTERCROPPING IN SUDAN SAVANNA, NIGERIA

The study was conducted during 2021 and 2022 rainy seasons; to determine the effects of Sesame (Sesamum indicum L.) as affected by NPK fertilizer rates and Cowpea [Vigna unguiculata (L.) Walp.] sowing dates in sesame and cowpea intercropping in Sudan savanna, Nigeria. The treatments consisted of four rates of NPK fertilizer (0, 50, 100, and 150 kg/ha) and three cowpea sowing dates (simultaneous sowing of cowpea with sesame, sowing of cowpea two weeks after sesame (CSAS) and sowing of cowpea three weeks after sowing the sesame (CSAS), laid out in a factorial arrangement, fitted into a split plot design and replicated three. The NPK fertilizer was assigned to the main plots while cowpea sowing dates were allocated to the sub-plot. Data on growth and yield parameters collected included plant height (cm), number of leaves per plant, leaf area per plant (cm2), number of capsules per plant, 1000 seeds weight (g) and seed yield per hectare (kg/ha ). The data generated from the study were subjected to Analysis of Variance (ANOVA) using Statistix 10.0 and where there is a significant difference; the means were separated using LSD at 5% probability level. Results revealed that NPK fertilizer had significantly improved the growth and yield of sesame. Sesame yield increased with increase in NPK fertilizer rates up to 100 kg ha-1. The highest grain yield obtained for the combined was 934.76 kg/ha. As for the cowpea sowing date, it was noticed that when the cowpea was sown three weeks after sesame, the yield of the sesame increased significantly. The interaction of 100 kg NPK/ha with three weeks after cowpea sowing recorded significantly greater grain yield in both years. Based on the findings, it is concluded that application of 100 kg NPK/ha with three weeks after cowpea sowing is recommended for sesame + cowpea in the Sudan savanna of Nigeria.

Appraisal of Heavy Metal Risk Hazards of Eisenia fetida-Mediated Steel Slag Vermicompost on Oryza sativa L.: Insights from Agro-Scale Inspection and Machine Learning Analytics

The steel industry drives world economic growth, yet it generates heavy metal-rich steel slag, which jeopardizes the environment. The utilization of vermi-technology is essential for the sustainable transformation of toxic steel waste slag (SW) into organic amendments, although field-scale use of vermiprocessed SW remains unexplored. To bridge the gap, this study evaluated the efficacy of vermiprocessed SW as an organic supplement for rice field cultivation, focusing on heavy metal (HM) bioavailability, human health risk, and yield in comparison to raw slag and NPK fertilizer. The results indicated a considerable decrease in the bioavailable fraction of heavy metals in T4 (1:1 SW vermicompost 50% + 50% fertilizer). In treatments, T9 (100% SW) and T10 (50% SW + 50% fertilizer) (FIAM) free ion activity modeling confirmed grain absorption of HMs, and the FIAM HQ values indicated the health risk for the direct application of steel slag waste on the field. The risk factor evaluation of HMs’ presence in treatments T9 and T10 established the possible cancer risk for living beings. Similarly, machine learning models like SOBOL sensitivity analysis and artificial neural networks revealed potential threats associated with HMs on different treatments, respectively. The correlation coefficient revealed the negative effects of bioavailable HMs on various soil microbial and enzymatic properties. Moreover, the abundant yield of rice was attributed to the combination treatment (1:1 50% + NPK 50%), which paved the way for an alternative agronomic approach based on the utilization of vermicomposted steel waste slag.

Effects of functional microbial agents on the microbial community and fertility of reclaimed soil in a coal mining area

Low soil fertility is the main factor limiting ecological restoration in coal mining reclamation areas. To improve the nutrient status and microbial community structure of reclaimed soil in coal mining areas, we tested a management strategy combining functional microbial agents, NPK, organic fertilizer, and straw to amend reclaimed soil. We selected corn as the crop for our greenhouse pot experiment, with a cultivation period of 80 days. Greenhouse pot trials were conducted with six treatments: no microbial agent (NMA), including CK (NPK), M (organic fertilizer and NPK), and S (straw and NPK); microbial agent (MA), including B (microbial and NPK), BM (microbial agent, organic fertilizer and NPK fertilizer), and BS (microbial agent, straw and NPK fertilizer). The results showed that the adding microbial agents changed the community structure of bacteria and fungi, and significantly changed the indicator microbial composition. The MA treatment group had an increase in five bacterial microbial network modules related to C and N functionalities such as Proteobacteria and Nitrospirae. In comparison to the B treatment, the combination of microbial agents with organic materials (BM and BS) significantly enhanced soil nutrient contents, including soil organic carbon (SOC), total nitrogen (TN). Therefore, the addition of functional microbial agents (Sphingomonas leidyi, Paenibacillus amylolyticus, and Paenibacillus mucilaginosus), especially in combination with organic materials, can significantly improve the contents of carbon, nitrogen and phosphorus nutrients, bacterial functional activity, and beneficial bacterial abundance in reclaimed soil, which is essential for the rapid improvement of reclaimed soil fertility in coal mining areas.

Effect of Palm Oil Mill Effluent (Pome) Concentration and Soil Type on the Growth of Oil Palm (Elaeis guinensis Jacq) in Pre-Nursery

The place of research was carried out at Educational and Research Garden of the STIPER Agricultural Institute which is located in Maguwoharjo Village, Depok District, Sleman Regency, Yogyakarta, Indonesia. The research location is located 118 meters above sea level. This research was conducted between March to June 2024. Two components make up the factorial experiment used in the Complete Randomized Design (CRD). The soil type had three levels: A1 = latosol soil, A2 = regusol soil, and A3 = grumusol soil, was the first factor. Palm Oil Mill Effluent (POME) concentration was the second factor. It was consisted into four levels: X1 was the control (NPK fertilizer), X2 was 150 ml per polybag, X3 was 300 ml per polybag, and X4 was 450 ml per polybag. So there were 12 treatment combinations (3 x 4 = 12) with 4 repetitions, so all the experiment 48 plants. Analysis of variance (ANOVA) was applied at the significant level of 5% to check the observation data. Duncan's Multiple Range Test (DMRT) was then used at a noticeable 5% level if there was significant difference. The weight parameters of fresh roots and the amount of chlorophyll in the leaves are influenced by the interaction of the soil and POME concentration. The composition, regusol soil and POME 450 ml/polybag provide an optimal combination of treatments. The type of soil has an impact on the weight of fresh and dry crowns, the number of leaves, the chlorophyll content in the leaves, the volume of roots, and the height of the plant. The best type of soil is regusol soil. Plant height, root volume, fresh and dry crown weight, and leaf chlorophyll content are all affected by POME concentration. The concentration of POME 450 ml/polybag showed the best results.

Soil application potential of post-sorbents produced by co-sorption of humic substances and nutrients from sludge anaerobic digestion reject water

This study introduces a novel soil conditioning approach using humic substances (HSs) and nutrients co-recovered from reject water from sewage sludge anaerobic digestion. For the first time, HSs and nutrients were simultaneously recovered through sorption on low-cost, environmentally inert materials: natural rock opoka (OP) and waste autoclaved aerated concrete (WAAC). This innovative application of OP and WAAC as carriers and delivery agents for soil-relevant substances offers potential for resource recovery and soil conditioning. Results indicate that the post-sorption opoka (PS-OP) and post-sorption waste autoclaved aerated concrete (PS-WAAC) effectively release retained HSs at 350–480 μg g⁻1 d⁻1, respectively. These materials also show potential as NPK fertilizers, releasing 280–430 μg g⁻1 d⁻1 N-NH₄⁺, 80–150 μg g⁻1 d⁻1 P-PO₄³⁻, and 270–350 μg g⁻1 d⁻1 K⁺. Additionally, PS-OP demonstrated promising fungicide properties, reducing P. diachenii growth by 31% at a concentration of 1 g L⁻1. A two-way ANOVA indicated that the effects of PS-OP and PS-WAAC on soil physicochemical and biological parameters varied with plant species. Both post-sorbents improved the quality of soil collected from sand mining area, increasing cation exchange capacity by 7%–85% and organic matter content by 10%–58%. They also enhanced the functional potential of soil microbial communities, increasing their metabolic activities by 23%–36% in soils sown with clover and by 33%–39% in soils sown with rapeseed. An opposite effect was observed in soils sown with sorghum, suggesting these amendments may not universally act as plant biostimulants. The effectiveness of these post-sorbents in enhancing plant growth varied depending on plant species and the mineral base of the post-sorbent. PS-OP increased the total length of clover and sorghum by 41% and 36%, and their fresh biomass by 82% and 80%, respectively. In turn, PS-WAAC increased the total length of clover and sorghum by 76% and 17%, and their fresh biomass by 29% and 15%, respectively. It was notably more effective than PS-OP for rapeseed. This study proposes a strategy to decrease reliance on non-renewable resources and costly sorbents while minimizing environmental impact. It shows that PS-OP and PS-WAAC can enhance soil quality, microbial activity, and plant growth. Given their origins, these amendments are recommended for soil remediation, particularly in degraded areas. Future research should focus on optimizing their application across various plant species to maximize effectiveness.

Factors influencing K-struvite purity via phosphorus coprecipitation in synthetic urine: Verification, Quantification, and Modelling

Due to its plethora of nitrogen (N), phosphorus (P), potassium (K) in urine, it is bound to trigger phosphorus coprecipitation, thereby adversely affecting K-struvite purity in the coprecipitates. To obtain high pure K-struvite, the present study was to innovatively explore the effect of residual NH4+ concentration, pH and initial Mg2+ concentration on phosphorus coprecipitation in synthetic urine. Importantly, a Back-Propagation Artificial Neural Network (BPANN) model was innovatively proposed to simulate and predict crystal purities in the coprecipitates. It was revealed that K-struvite, struvite, hydroxyapatite and cattiite dominated the coprecipitates. Comparatively, the content of calcium in synthetic urine is far lower than that of phosphorus and potassium, resulting in low hydroxyapatite purity in the coprecipitates. Notably, cattiite purity is highly dependent of Mg2+ concentration, because it was low at the Mg2+ concentration of <10 mmol/L, but increased up to above 50% at the Mg2+ concentration of 50 mmol/L.At 10 mmol/L Mg2+ and pH 10, K-struvite purity in the coprecipitates decreased from 64.6% to 43.3% following the increase of NH4+ concentration from 0 to 300 mg/L. The BPANN model well simulated and predicted the purities of the crystals in the coprecipitates from synthetic urine. At 10 mmol/L Mg2+ and 100 mg/L NH4+, an increase in pH from 8.5 to 10 can facilitate K-struvite crystallization in synthetic urine. The adjustment of pH and initial Mg2+ concentration can significantly mitigate the inhibitory effect of residual NH4+ on K-struvite crystallization. The BPANN model herein can effectively obtain optimized operational parameters for the full-scale implementation of slow-release NPK fertilizers from urine, which can also provide an effective reference for nutrient recovery from various waste streams.

Fertilization effects on soil organic matter chemistry

Despite the close interactions between carbon (C) and nutrients like nitrogen (N), phosphorus (P), and potassium (K), the consequences of N fertilization alone or in combination with P and K on soil organic matter (SOM) chemical composition remain unclear. Using solid-state 13C nuclear magnetic resonance spectroscopy data from 45 field studies, we meta-analyzed the effects of N alone and NPK fertilization on SOM content and chemical composition. Generally, mineral fertilization affects the SOM content and composition via three indirect processes: i) increasing litter input and rhizodeposition, ii) accelerating microbial decomposition of SOM, and iii) modifying the preservation of SOM by soil minerals. NPK fertilization (+12 %) increased organic C content more than N fertilization alone (+8.6 %). Alkyl and O-alkyl C increased at low-N rates (<50 kg N ha−1 yr−1) or after short-term (0–5 yrs) N fertilization alone, likely because improved N availability promoted bacterial residues rich in long-chain aliphatic C formation and carbohydrate-rich matter inputs. High-rate (>200 kg N ha−1 yr−1) or long-term (>25 yrs) NPK fertilization increased alkyl C but decreased aromatic C, likely due to reduced nutrient limitations and acidification. These factors promote aliphatic C-rich microbial biomass, accelerate the decomposition of stable compounds, and decrease the mineral protection of aromatic acids. The SOM chemical composition (excluding aromatic C) response to NPK fertilization decreased with increasing initial level. In contrast, the response of SOM raised with increasing initial content under N fertilization alone. The increase in organic C content was strongly linked to changes in SOM chemistry under NPK fertilization but not under N fertilization alone. In conclusion, NPK fertilization modified SOM chemistry and increased organic C accumulation more effectively than N fertilization alone, which was mediated by increasing plant growth, raising microbial biomass and activity, altering mineral protection, and initial soil C levels. Our findings provide critical insights for optimizing fertilization strategies to improve soil C sequestration capacity and fertility.

Technical and Economic Efficiency of Production Factors in Javanese Tobacco Farming: A Case Study of Belun Village, East Java

This study analyzes the technical and economic efficiency of production factors in tobacco farming in Belun Village, Temayang Subdistrict, Bojonegoro District, East Java. Using stochastic frontier software 4.1, the analysis was conducted with a sample of 87 Javanese tobacco farmers. The production inputs evaluated include land area, seeds, urea fertilizer, NPK fertilizer, NPK Phonska Plus fertilizer, labor, pesticides, and production output. The results indicate that the gamma elasticity coefficient for technical efficiency is 0.949, with all variables being statistically significant at the 1% level (t-table 2.64), except for pesticide input, which is significant at the 5% level (t-table 1.99). In the economic efficiency analysis, seedlings were identified as the inefficient input with an efficiency estimate (EE) of &gt; 1 (52.4), while other inputs showed EE &lt; 1. The study concludes that 94.9% of the inefficiency stems from production factors, while 5.1% is attributed to external factors. Moreover, the inputs used in Javanese tobacco farming are neither technically nor economically efficient. To achieve full technical efficiency, farmers should reduce inputs such as land area, NPK fertilizer, and NPK Phonska Plus fertilizer, while increasing the use of seeds, pesticides, urea fertilizer, and labor.

Chitosan-based NPK nanostructure for reducing synthetic NPK fertilizers and improving rice productivity and nutritional indices

Researchers have repeatedly emphasized how urgently we have to decrease the massive nitrogen fertilizer consumption to support agricultural productivity and maintain a sustainable ecosystem. Using chitosan (CS) as a carrier for slow release is considered a potential tool for reducing synthetic fertilizer and improving crop productivity. Therefore, two field experiments were arranged in a randomized complete block design to investigate the effects of seven treatments including synthetic fertilizer and exogenous application of chitosan-based NPK nano-structure (Ch/NPs-NPK) on growth, productivity, and nutrient uptake traits of rice as a worldwide strategy crop during 2022 and 2023 growing seasons. The experimental treatments were: T1 = full recommended synthetic NPK (recommended urea, superphosphate, potassium sulfate; control treatment), T2 = 70% of T1 + Ch/NPs-NPK 100 ppm, T3 = 70% of T1+ Ch/NPs-NPK 200 ppm, T4 = 70% of T1+ Ch/NPs-NPK 300 ppm, T5 = 30% of T1+ Ch/NPs-NPK 100 ppm, T6 = 30% of T1+ Ch/NPs-NPK 200 ppm, and T7 = 30% of T1 + Ch/NPs-NPK 300 ppm. The results revealed that T4 (i.e., 70% of recommended NPK+ Ch/NPs-NPK 300 ppm) and T1 (full recommended synthetic NPK) resulted in the highest and most significant growth and yield traits of rice as well as nutrient grain contents compared to other treatments. Therefore, combining 70% of recommended NPK with Ch/NPs-NPK 300 ppm as an exogenous application can be a smart choice for reducing synthetic NPK fertilizers by 30% in paddy fields without producing a significant decline in terms of growth, yield characteristics, or nutrient grain contents when applying the full recommended synthetic NPK.

PENGARUH LARUTAN PUPUK HAYATI ENDOMIKORIZA ASAL AKAR MERANTI TERHADAP PERTUMBUHAN DAN PRODUKSI TANAMAN KANGKUNG

Water spinach (Ipomoea sp) is a plant that is widely consumed by people as a vegetable because it is cheap and easy to cultivate. The main problems in growing water spinach are soil fertility and attack by plant pests and diseases. To increase production from kale farming, farmers generally use inorganic fertilizers such as NPK which in reality can cause environmental pollution. For this reason, various efforts to use organic (environmentally friendly) fertilizers such as fungal and bacterial biofertilizers remain the focus of research to date. Mycorrhizal fungi are known to have quite a lot of benefits for plants, especially in providing phosphate and nitrogen nutrients for host plants. In the forestry sector, it is known that the roots of meranti plants (Shorea sp) and the roots of pine plants (Pinus sp) are natural hosts for the growth and development of mycorrhizal fungi. Therefore, the aim of this research is to determine the effect of endomycorrhizal solution fertilizer from meranti roots on the growth and production of water spinach plants. The results of the research show that the endomycorrhizal biofertilizer solution from meranti roots produces growth and production of water spinach plants that are not significantly different from the NPK fertilizer treatment, so from an environmental safety aspect, it is proposed that it is better to use endomycorrhizal biofertilizer because it is environmentally friendly.

Slow release of NPK fertilizer using biodegradable porous carriers synthesized from agricultural waste

This study investigates the synthesis of porous biodegradable materials from rice bran and pineapple waste to determine their potential as carriers for slow-release NPK (Nitrogen, Phosphorus, Potassium) fertilizers. Through gel formation, solvent exchange, and carbonization; agro-waste gets converted into highly porous materials. A further examination of these materials demonstrates their adsorption capability and efficacy in progressive NPK fertilizer release. Experimental results show that both rice bran and pineapple waste-derived materials are effective slow-release fertilizer carriers. However, comparative investigation shows that rice bran-based material has better slow-release properties than its pineapple waste-derived counterpart. Here we also include the kinetic study of the release rate of NPK fertilizers which turned toward a Pseudo-zero order of release rate. This study emphasizes the necessity of repurposing agricultural byproducts for sustainable material synthesis, which contributes to the advancement of green chemistry and provides eco-friendly fertilizer delivery systems.

Growth Increase of Gelam (Melaleuca Leucadendron) Burnt Peatland Through the Provision of Soil Conditioner (Study in Londerang Peat Protection Forest)

The protected forest of Londerang Jambi is an area of hydrological unity with a surface area of 12.484 ha that is located in the district of Tanjung Timur and Muaro Jambi, which is surrounded by palm plantations and forest of industrial crops and 10 villages in the Districts of Tanjung Jabung Timur and Jambi. Based on the results of the Landsat 8 OLI image analysis and the SPOT 7 image interpretation by WWF Indonesia in 2015 that the Londerang Forest Protection Area (HLG) has an area of 12.848 Ha, currently the steep vegetation cover that canopies closely on the HLG Londerang remains only less than 10% of the area of HLG londerang due to forest fires in 2015. An attempt to overcome the situation has been made, one of them in the HLG Londerang being made an of the Hydrological Union of Mendahara-Sungai Batanghari which has been intervened by the Badan Restorasi Gambut (BRG). This effort was also carried out by the KIFC (Korea Indonesia Forest Center) by revegetating the blocks of land that had been burned in HLG Londerang. The planting has been carried out from the beginning of 2022 to December 2022. The species of plants planted among them are Pulai Rawa (Alstonia scholaris), Balangeran (Shorea balangeran), Gelam (Melaleuca leucadendron). In order to support the success of the revegetation, intensive maintenance is required, including the provision of soil fertilizers such as dolomite and NPK fertilizer. The research was conducted for seven months from May to December 2023 at HLG Londerang. Measuring fields are made with group random designs (RAK). The clustering is based on the difference in the height of the groundwater surface

Evaluation of nitrogen use efficiency and N-supplying capacity on pomelo (Citrus grandis L. Osbeck) grown on alluvial soil in the Cuu Long Delta

The study was conducted to determine the nitrogen use efficiency (NUE) and the ability to provide nitrogen from alluvial soil for growing pomelo (Citrus grandis L. Osbeck) in the Mekong Delta. The experiment was arranged in a randomized complete block design including two treatments (NPK treatment: 673 N - 385 P2O5 -192 K2O g/plant and PK treatment: 0 N - 385 P2O5 - 192 K2O g/plant) and three replicates (3 plants for each replicate). The results showed that fruit yield was highest (39.1 kg/plant, N recovery efficiency of 53.8%) in the full NPK fertilization treatment and lowest in the PK fertilization treatment (18.5 kg/plant). Calculation results of the ability to supply nitrogen to pomelo trees in Chau Thanh, Hau Giang showed that alluvial soil had the ability to provide 49.6% of N and the remaining 50.4% from additional fertilizer sources for maximizing fruit yield.

Optimizing Olive Production: The Role of Foliar Fertilizers in Boosting Yield and Quality

To enhance yield and produce high-quality olive products, it is crucial to implement accurate and balanced fertilization programs. Like other crops, olive trees require the application of specific macro and micronutrients in addition to basic fertilization. This study aimed to evaluate the effects of foliar fertilizer applications containing K as well as N, K, Ca, and B, in addition to basic fertilization, on the yield and quality parameters of the Gemlik olive (Olea europaea L. cv. Gemlik) variety, known for its high economic value and use in black table olives and oil production, during two consecutive seasons in 2021–2022. The research evaluated the effects on olive fruit yield, fruit nutrient content (N, Ca, P, Na, K, Mg, Zn, Fe, Cu, and Mn), oil yield, and quality. In addition to traditional basic fertilization (NPK fertilizer), foliar fertilizers containing K as well as N, K, Ca, and B nutrients were applied before flowering and after fruit set. These applications were organized using a randomized block design with three replicates, each consisting of three trees. The results showed that foliar fertilizer applications, in addition to basic fertilization, had a significant impact on the yield and quality parameters. Specifically, foliar K applications positively affected olive yield in the second year. Moreover, foliar fertilizer applications improved the fruit nutrient content, oil quality (K-232, K-270, peroxide, acidity, and total phenol), and oil composition (%). Therefore, it is recommended that foliar fertilizers are applied during similar periods under similar conditions. However, ensuring the continuity of an optimal fertilization management plan is crucial for olive, as it is a perennial plant.

Respon Pertumbuhan dan Produksi Bawang Merah (Allium ascalonium L.) Terhadap Pupuk NPK

North Sumatra is shallots. Shallot (Allium ascolonicum L.) is a horticulture that has many benefits for people's lives, both from economic value and nutritional content, so that shallot production increases every year and is proven based on BPS (Central Statistics Agency) for the last 5 years. The effort needed to meet the needs of shallot production is to increase soil productivity, using the addition of NPK fertilizer. This study used factorial randomized group design (RAK). For accuracy in this study, it was repeated 3 times. namely: NPK fertilizer (N) with 3 levels, namely: N0 = Control, N1 = 5 g/plant, and N2 = 10 g/plant. The results of the Anova Variance test showed that the response of NPK fertilizer treatment to plant height 3 mst, 4 mst, 5 mst, 6 mst and wet weight of tubers per plot (g) had a significant effect, but the observation of the number of tubers per sample plant (tubers), and the diameter of tubers per sample (mm) had no significant effect. Keywords: NPK fertilizer, NPK dosage, and shallots

Pengaruh Aplikasi Pupuk NPK Terhadap Pertumbuhan dan Produksi Tanaman Wortel (Daucus carota L.)

Indonesia is one of the tropical countries that has a variety of plants including vegetables and fruits. One that has the largest production is carrots (Daucus carota L.). Carrots are a type of shrub-shaped vegetable plant, which grows upright with a height of 30-100 cm or more. Carrots (Daucus carota L.) are a tuberous vegetable type plant that is usually reddish yellow or yellowish orange with a wood-like texture. The edible part of a carrot is the bulb or root. The plant stores food reserves in the bulb. The stem is short, has a taproot that changes its shape and function into a round and elongated tuber. The skin of carrot bulbs is thin and if eaten raw, it feels crunchy and slightly sweet. Here's a picture of a carrot plant. One way to increase the yield of carrot plants is by increasing soil productivity, using the addition of NPK fertilizer. This study used a factorial randomized group design (RAK). For accuracy in this study, it was repeated 3 times. namely: NPK fertilizer (N) with 3 levels, namely: N0 = Control, N1 = 15 g/plot, and N2 = 25 g/plot. From the ANOVA test results, the variance of treatments that have a significant effect is continued with the Duncan DMRT test at the 5% level. The results of the ANOVA test showed that the effect of NPK fertilizer treatment on plant height 21 hst and 28 hst, the number of leaves had no significant effect, but the observation of the diameter of the base of the tuber, the fresh weight of the plant per sample and the fresh weight of the plant per plot had a significant effect. Keywords: NPK fertilizer, NPK dosage, and carrot plants