Fertilizer Recommendations Research Articles

Soil fertility management on sesame (Sesamum indicum L.) production in Northern Ethiopia: A review.

Sesame (Sesamum indicum L.) is an important cash crop and plays a vital role in many people's livelihoods in Ethiopia. However, its production is low due to many constraints, and low soil fertility is among the major. The previous fertilizer recommendation was a blanket recommendation regardless of the soil fertility status. Hence, the objective of this review is to synthesize the different recommendations and forward to the sesame growing areas. R statistical software and Python programming language used to analyze the chemical and physical soil properties, association among the chemical and physical soil properties and association with soil depth. The organic carbon, total N (Nitrogen), available P (Phosphorus), S (Sulfur) and Zn (Zinc) are below optimum value while K is sufficient in the soil and moderately alkaline soil. The soil particle size is dominantly clay (58.5%). The clay particle size and pH increased while the sand and silt particle sizes, organic carbon, total N, available P and S decreased as the soil depth increased. 204,558.8 ton of sesame stack residue are burned every year, and from this, 7360.03 ton of NPK is lost every year in Western Tigray. The recommended N, P and S for sesame are: (i) 64 and 41kgha -1N for low N content areas and for medium N content areas respectively; 46 and 23kgha -1 P2O5 for low and medium P content areas; (iii) 60 and 30kgha -1S for low medium S content areas may be recommended to boost sesame production.

Boron Behaviors in Upland Humid Tropical Soils: A Case of Plant-Available Implication for Cassava

ABSTRACT Understanding the role of soil boron (B) through its reaction, mobility, and availability could provide effective B nutritional management for a cassava crop (Manihot esculenta crantz). This study investigated a soil B status suitable method for making B fertilizer recommendation through determining the B sorption index and the chemical fractionation of soil B and available B in soils, using single extractants in 11 benchmark soils intensively cultivated for cassava in northeast, Thailand. All soils studied were considered low B-sorbed soils that were equally well described using either Langmuir or Freundlich models, with respective adsorption capacities of 2.00–17.22 mg kg−1 and 0.91–4.31 L mg−1. The B desorption index exhibited hysteresis desorption behavior for all soils. Boron adsorption by the soils significantly showed a positive correlation (>0.75, p ≤ .01) with organic carbon, silt, amorphous aluminum, and silicon contents. Of the total B, the native B pool in the soils was mostly in the residual fraction, contributing 70–80%, while the readily soluble fraction contributed only 0.07–0.59%. Among the soil extractants tested, only hot CaCl2 and NH4OAc adequately assessed soil B availability for cassava, while they were less extractability to extract B from total B. Chemical fractions of B could all be used for available B assessment for cassava with a residual B fraction being superior, although this was unlikely to contribute significantly to plant-available B in the short term, but it was a potential B reserve that could maintain adequate B status in the long term throughout the cassava growing period.

Spatial and Temporal Variability Management for All Farmers: A Cell-Size Approach to Enhance Coffee Yields and Optimize Inputs.

Coffee yield exhibits plant-level variability; however, due to operational issues, especially in smaller operations, the scouting and management of coffee yields are often hindered. Thus, a cell-size approach at the field level is proposed as a simple and efficient solution to overcome these constraints. This study aimed to present the feasibility of a cell-size approach to characterize spatio-temporal coffee production based on soil and plant attributes and yield (biennial effects) and to assess strategies for enhanced soil fertilization recommendations and economic results. The spatio-temporal study was conducted using a database composed of yield and soil and plant attributes from four harvest seasons of coffee plantation in the southeast region of Brazil. We used small plots as cells, where soil, leaf, and yield samples were taken, and the average value of each variable was assigned to each cell. The results indicated that macro- and micronutrient contents in the soil and leaves exhibited spatio-temporal heterogeneity between cells, suggesting that customized coffee tree management practices could be employed. The cell-size sampling strategy identified regions of varying yield over time and associated them with their biennial effect, enabling the identification of profitable areas to direct resource and input management in subsequent seasons. This approach optimized the recommendation of potassium and phosphate fertilizers on farms, demonstrating that localized management is feasible even with low spatial resolution. The cell-size approach proved to be adequate on two coffee farms and can be applied in scenarios with limited resources for high-density sampling, especially for small- and medium-sized farms.

Relationships among soil test potassium forms influenced by clay mineralogy

AbstractPotassium fertilizer recommendations for optimal crop production may be improved by considering the ratio between expanding 2:1 layer silicates (smectite) with non‐expanding 2:1 layer silicates (illite). However, the interactive effects between clay mineralogy and various soil tests are not well understood. This study evaluated the relationships among soil test K (STK), water‐soluble K, HNO3‐extractable K, pH, apparent cation exchange capacity (CECa), soil organic matter, clay content, and smectite:illite ratios. Soil samples (0–15 cm) were collected from 41 locations in central and eastern South Dakota, with textures ranging from sandy loam to clay. Data were partitioned into soils with smectite:illite ratios < 1 (illitic), ≥1 but ≤4.5 (smectitic), and > 4.5 (highly smectitic). Mean pH and CECa were lowest in illitic soils, higher in smectitic soils, and highest in highly smectitic soils, whereas STK and water‐soluble K were lowest in highly smectitic soils relative to illitic and smectitic. Correlation analysis also showed that STK decreased with increasing smectite:illite ratio. These results suggest that exchangeable and water‐soluble K forms are reduced when the proportion of smectite increases. There was a strong, positive relationship between STK and HNO3‐extractable K across all three smectite:illite ratio groups. For soil pH, however, the relationship with STK was positive for illitic and smectitic soil groups, but negative for highly smectitic soils. Overall, these results suggest that the smectite:illite ratio influences the relationship among soil parameters and STK. This improves our understanding of the influence of clay mineralogy on plant‐available K and the implications for K fertilizer recommendations.

Assessment of Micronutrient Deficiencies in Agricultural Soils of Hasanganj and Auras Blocks, Unnao District, Uttar Pradesh, India: Implications for Sustainable Farming

This study evaluated the status of essential micronutrients in the soils of Hasanganj and Auras blocks in Unnao district, Uttar Pradesh, India, during 2020–2021. A total of 200 surface soil samples from five villages in each block were analyzed for zinc, boron, copper, manganese, and iron content. The findings revealed significant deficiencies, particularly in zinc (39.5%) and boron (32.5%), with potential implications for crop productivity and soil health. The study emphasizes the urgent need for balanced nutrient management and soil-specific fertilizer recommendations to address these deficiencies and support sustainable agricultural practices. These results provide a valuable baseline for future research and policy interventions aimed at improving soil fertility and food security.

Nutrient uptakes and use efficiency of cassava under different moisture conditions

AbstractPrecise fertilization based on crop needs is important for optimal yield and cost‐effectiveness. This study aimed to investigate nutrient uptakes in cassava under different planting dates and irrigation conditions (W). Two‐year field trials were conducted in the early (ERS) and post‐rainy seasons (PRS), with nutrient uptakes measured at five growth stages. Planting dates had a greater impact on nutrient uptakes, accumulation rates, nutrient harvest index (NHI), and nutrient use efficiency (NUE) than W. In the ERS, the nutrients accumulated rapidly at the early to mid‐growth stages, while this occurred at the mid to late growth stages for the PRS. Nutrient uptake was higher in ERS than PRS, with W differenced only in ERS 2015. Irrigation during the mid to late growth stages increased the nutrient uptake, NHI, NUE, and yield for the ERS (2015), with less impact on the PRS. In contrast, the PRS significantly improved yield, accumulation in storage roots, NHI, and NUE. Total nutrients accumulated by the whole plant (kg ha−1) were N (207–383) > K (182–401) > Ca (180–202) > Mg (62–82) > P (42–76) > S (11–25), Fe (2.60–7.64) > Mn (1.60–3.34) > Zn (0.48–0.62) > B (0.15–0.25) > Cu (0.11–0.19) > Mo (0.026–0.055). Nutrients with high NHI were K (0.41–0.64), Zn (0.35–0.58), N (0.28–0.56), Cu (0.16–0.61), B (0.16–0.52), and Mo (0.19–0.62), and lower NHI were P (0.27–0.47), Mg (0.17–0.37), S (0.15–0.48), Fe (0.15–0.34), Ca (0.09–0.19), and Mn (0.04–0.31). These findings will improve nutrient requirement guidelines for seasonal fertilizer recommendations for cassava in Thailand.

Site-Specific Online Fertilizer Recommendations in Small Cardamom (Elettaria cardamomum (L.) Maton through CardSApp offers fertilizer savings and higher economic returns

The cultivation of small cardamom in the Indian Cardamom Hill (ICH) region of the Western Ghats, southern India, has become highly intensive, with heavy use of fertilizers and pesticides. The cultivation of small cardamom in the Indian Cardamom Hill (ICH) region of the Western Ghats, Southern India, has become highly intensive, with heavy use of fertilizers and pesticides. The ICH region is one of the world's biodiversity hotspots. Numerous studies have reported that the excessive use of chemical fertilizers has caused soil acidification (lowering of pH) and nutrient imbalances. This has resulted in unsustainable production of cardamom, a high-value spice crop that contributes significantly to India's export earnings. This study aimed to conduct a geo-tagged soil fertility survey in selected cardamom-growing areas within the ICH, assess soil fertility and provide sitespecific fertilizer recommendations to farmers via a mobile- or web-based application. A digital application, CardSApp, designed for the small cardamom sector, offers tailored fertilizer recommendations based on local soil and crop requirements. A representative geo-tagged soil survey was conducted in Udumbanchola taluk, located in Idukki district of Kerala, within the ICH. The surveyed area spanned from 76°59'01.19'' to 77°16'11.55'' East longitude and 9° 38'21.54'' to 10°04'46.60'' North latitude. Spatial interpolation techniques were used to generate maps showing the distribution of primary, secondary and micronutrients in the soil. The study revealed a high availability of NPK nutrients in cardamom soils. The study also revealed deficiencies in secondary nutrients like magnesium and sulfur, as well as micronutrients such as boron. Most of the soils showed signs of acidification. These findings highlight opportunities to optimize fertilizer usage and improve soil health. Specifically, NPK usage can be reduced or phosphatic fertilizers omitted in 58% of the area, potentially savings of ?12.27 crores annually in the surveyed taluk alone. Additionally, addressing deficiencies in secondary and micronutrients can further enhance soil health and crop productivity. To aid farmers in decision-making, the Android- and web-based application CardSApp leverages interpolated soil fertility data. CardSApp offers site-specific recommendations tailored to the soil nutrient profiles identified in the survey. CardSApp enables farmers to optimize fertilizer use, correct nutrient imbalances and apply amendments for pH correction. These practices can improve both farm productivity and income. The adoption of this online fertilizer recommendation system by farmers in the ICH is expected to rationalize fertilizer usage in cardamom cultivation, improve both soil and plant health and support sustainable production with higher economic returns.

Energy Assessment in Rabi Sunflower under Varying Drip Irrigation Regimes and Fertigation Levels

Efficient Irrigation and Nutrient Management Strategies are Important for Sustainability of Agriculture. In order to elucidate the above hypothesis, an on-farm experiment was carried out at Water Technology Centre, PJTSAU, Hyderabad to study the effect of different combinations of drip irrigation regimes and fertigation levels on energy dynamics under Rabi sunflower. The experimental design was split-plot design and contained three replications for DRSH-1 sunflower variety. Three treatments of drip irrigation were compared as main plots (0.8 Epan, 1.0 Epan and 1.2 Epan base values of the Epan pan) and four levels of fertigation at the sub-plots (60%, 80%, 100% and 120% of the recommended dose). 75:90:30 kg NPK ha-1 was set for the fertilizer recommendation. Energy parameters: energy output, energy efficiency, net energy gain, energy profit, and energy intensity were assessed across treatment combinations. The findings indicated that peak energy consumption transpired under settings integrating 1.2 Epan irrigation with a 120% recommended dosage of N and K₂O fertigation. The optimal irrigation level was 1.0 Epan, which produced enhanced outcomes in energy output (102.6 GJ ha-1), use efficiency (5.02), and nett energy gains (90.1 GJ ha-1) relative to lower irrigation levels. The application of the full prescribed dose in fertigation treatments proved to be excellent, exhibiting exceptional performance across all energy metrics: output (105.6 GJ ha-1), usage efficiency (8.1), nett energy (92.5 GJ ha-1), profitability (0.223), and intensiveness (0.0022). Statistical study revealed no significant interaction between irrigation and fertigation treatments, indicating that these parameters independently affect energy efficiency indicators.

Influence of location-specific nutrient management and plant stand on the growth, productivity, and nutrient uptake of irrigated rabi maize (Zea mays L.)

Cereals are essential for global food security and serve as a primary source of dietary energy for 60% of the world's population. Maize, among the prominent cereals, stands out as a highly adaptable crop with versatility across diverse agro-climatic zones, fulfilling demands for food, feed, and fodder worldwide. While progressive farmers often adhere to conventional fertilizer recommendations set by authorities, this practice can sometimes result in suboptimal productivity with a negative impact soil health over time. In this context, the Nutrient Expert (NE) can be considered an efficient decision support system for field-specific recommendations for precision nutrient management in maize. Plant density is a vital agronomic trait determining the grain yield of maize. Considering these, a field study was conducted for two consecutive years at the Post Graduate Research Farm of Centurion University of Technology and Management, Paralakhemundi, Odisha, India (18.8° N latitude, 84.8° E longitude) during the rabi season of 2022-23 and 2023-24. the present research was conducted by adopting a split-plot design which comprised three main plot treatments with different levels of plant population (P1: 66666 plants/ha; P2: 83333 plants/ha; P3: 111111 plants/ha) and four sub-plot treatments consisting of nutrient management treatments (T1: 100 % RDF, T2: Nutrient Expert-based recommendation (NE) for a target yield of 6 t/ha, T3: NE for a target yield of 8 t/ha and T4: NE for a target yield of 10 t/ha). The experimental soil was sandy clay loam in texture with slightly acidic pH and low in available nitrogen and organic carbon, and medium in phosphorous and potassium. The results of the experiment revealed a significant difference among the growth parameters, yield attributing characters, yield and nutrient uptake of maize concerning plant population and nutrient levels. The study concluded that applying primary nutrients through NE @ 10 t/ha along with a plant population of 1,11,111 plants/ha could be chosen as the most suitable agronomic practice for improving growth and productivity in irrigated rabi maize under Odisha conditions.

Combination Effect of NK and P Fertilizers on Soil Available-K, K Absorption, and Sweet Corn Productivity in Inceptisols

One factor affecting sweet corn's (Zea mays saccharata Sturt.) productivity refers to soil fertility and proper fertilization. This study aimed to determine the optimal combination of NK and P fertilizer doses to enhance the growth and yield of corn grown on Inceptisols. This research was conducted at the Soil Chemistry and Plant Nutrition Experimental Field, Faculty of Agriculture, Universitas Padjadjaran. The Randomized Block Design consisted of 10 treatments with three replicates each. The treatments included: A, control; B, standard NPK; C, ¼ dose NK + 1 P + ½ N; D, ½ dose NK + 1 P + ½ N; E, ¾ dose NK + 1 P + ½ N; F, 1 dose NK + 1 P + ½ N; G, 1¼ dose NK + 1 P; H, 1 dose NK; I, ½ dose NK + ½ single N,P,K; and J, ¾ dose NK + ¼ single N,P,K. The results showed that the combination of NK and P fertilizers significantly affected the growth and yield of sweet corn. The treatment with ¾ NK + 1 P + ½ N had a notable impact on cob weight (0.33 kg/cob), cob diameter (5.05 cm), and cob length (21.2 cm). This treatment also increased K absorption to 34.49, available soil K to 2.45 cmol kg-1, and the sweetness level of corn to 13.56%. This study provides new recommendations for corn fertilization to improve the growth and yield on Inceptisols. Keywords: optimal fertilizer dosage, corn growth, corn productivity, nutrient uptake

GreenThumb Advisor: Smart Farming Solutions for Higher Yields and Informed Decisions

GreenThumb Advisor is a Python-driven application [1] designed to enhance agricultural productivity by providing Indian farmers with actionable, data-informed insights. Leveraging advanced machine learning techniques, the application recommends optimal crop [2] selections based on vital soil and environmental indicators—such as nitrogen, phosphorus, potassium levels, pH, humidity, and rainfall—to align with region-specific conditions. Yield forecasting, powered by historical crop data, offers farmers predictive insights into potential harvest outcomes, supporting informed financial planning. In addition to crop guidance, GreenThumb Advisor integrates a 30-day weather forecast, enabling farmers to plan agricultural activities around forecasted weather patterns [3]. Real-time notifications ensure farmers receive critical updates through SMS and email, minimizing weather-related risks. The application also supports practical farm management with features such as emergency service mapping, tailored fertilizer and pesticide recommendations, market price tracking and a library of awareness videos. With its intuitive interface, GreenThumb Advisor empowers farmers to improve yield, make data-driven decisions, and foster sustainable agricultural practices.

Evaluation on the Influence of Cropping Systems and Nutrient Management Practices in Pearl Millet (Pennisetum glaucum) Growth, Crop Nutrient Uptake and Soil Fertility Status

Background: At the present situations, sole croppingand generalized fertilization recommendations could not produce advantageous results for neither profitable crop production nor for a sustainable environment. Therefore, the study focuses on evaluating the response of pearl millet to various cropping systems and different nutrient management techniques for enhancing crop productivity and sustaining soil fertility. Methods: The field trial took place at the instructional farm of Karunya Institute of Technology and Science in the Coimbatore district of western Tamil Nadu, India. The trial spanned over two growing seasons and followed a factorial randomized block design, with 2 factors: cropping systems and nutrient management, replicated three times. The design resulted in a total of 12 treatment combinations, comprising 3 levels of cropping system viz., sole cropping of pearl millet, pearl millet with black gram and cowpea intercropping systems; and 4 levels of nutrient management comprising different doses of fertilizer levels in combination with biofertilizers such as Azospirillum and PSB and foliar sprays of 2% Urea and 3% Panchagavya. Result: The experimental findings indicated that intercropping treatment, Pearl millet + Black gram at a 1:1 ratio, exhibited superior results in enhancing plant growth, improving the crop nutrient uptakeand enriching soil fertility. In the case of nutrient management treatments, application of 75% of recommended dose of fertilizers (RDF) + Azospirillum and phosphate solubilizing bacteria + foliar application of 2% urea at 15 and 35 days after transplanting (DAT) resulted in producing higher plant height, enhanced dry matter production, efficient crop nutrient uptake, improved soil fertility status for sustainable agriculture.

Evaluation of the Egner–Riehm DL and Mehlich 3 Tests for the Determination of Phosphorus: The Influence of Soil Properties on Extraction Efficiency and Test Conversion

The leaching of phosphorus (P), together with nitrogen (N), into deep water and runoff from fields into surface water has caused the dangerous phenomenon of eutrophication, which threatens the Baltic Sea. This process has led to a revision of fertilizer recommendations for farmers in most European countries. The basis for proper recommendations is the determination of soil P using a soil test. There are many different soil tests used in Europe for the determination of plant-available P in soil, which is primarily the result of the different soil conditions in the individual countries. In Poland, two soil P tests are currently used: the Egner–Riehm DL (DL) test and the Mehlich 3 (M3) test. The aim of our study was to determine the extraction efficiency of the DL and M3 tests, to explore the possibility of converting the results of one test to another, and to compare the diagnostic value of the tests. For this purpose, a collection of 237 soil–plant sample pairs was taken from maize fields in Poland. The phosphorus content was determined in all the soil and plant samples, with two methods used in the soil samples: DL and M3. The results of our study show that it is not possible to state unequivocally which test extracts more P from the soil. The extraction efficiency of the tests depends on the specific soil properties, particularly pH and texture. The most reliable conversion of DL test results to M3 is possible for soils that contain a 21–35% fraction characterized by particles less than 0.02 mm in diameter, regardless of soil pH. Furthermore, the DL test has better diagnostic value than M3, especially for alkaline soils.

Intelligent Agriculture System using KNN Algorithm

The agricultural sector faces the challenge of maximizing crop yields while maintaining sustainability and resource efficiency. Nostalgic or Romantic Views, oftenreliant on manual monitoring and subjective decision-making, can result in inefficiencies and lower productivity. To address these issues, an intelligent agriculture system utilizing the K-Nearest Neighbors (KNN) algorithm has been proposed. This paper presents an intelligent agriculture system that leverages the K- Nearest Neighbors (KNN) algorithm to enhance crop management and yield prediction. By analyzing various environmental factors such as soil moisture, temperature, and humidity, the system accurately classifies the optimal planting and harvesting times for different crops. Additionally, it provides real-time recommendations for irrigation and fertilization based on predictive analysis. The integration of KNN allows for adaptive learning from historical data, thereby improving decision-making processes for farmers. This approach aims to optimize resource utilization, increase productivity, and promote sustainable agricultural practices. The proposed intelligent agriculture system leverages the K- Nearest Neighbors (KNN) algorithm to enhance crop management and sustainability. By analyzing real-time environmental data and historical agricultural records, the system provides precise recommendations for optimal planting and harvesting times, efficient irrigation schedules, and tailored fertilization strategies. This data-driven approach aims to increase crop yields, optimize resource utilization, and reduce the environmental impact of farming practices. The system's continuous learning capability allows it to adapt to changing conditions, ensuring that farmers receive up-to-date and accurate guidance. Overall, the integration of KNN in agriculture represents a significant advancement towards sustainable and efficient farming.

Establishment and Evaluation of Soil Fertility Gradient on the Basis of Sorghum Fodder Yield, Nutrient Uptake and Post-Harvest Soil Test Values

Field experiment was carried out with fodder sorghum at N.E. Borlaug Crop Research Centre, G.B.U.A.&T., Pantnagar during kharif, 2022 under AICRP on Soil Test Crop Response (STCR) approach aimed to establish and evaluate soil fertility gradient on the basis of sorghum fodder yield, nutrient uptake and post-harvest soil test values. The experimental field was divided into three plots, each receiving graded levels of N, P2O5 and K2O: N0P0K0 (Plot A), N100P100K100 (Plot B) and N200P200K200 (Plot C). Thereafter, fodder sorghum was grown and fodder yield was recorded from each plot. Chemical analysis of plant samples was performed to estimate nitrogen, phosphorus and potassium content and total nutrient uptake was worked out. Post-harvest soil samples were collected across the three plots and analysed for available N, P and K. Findings revealed wide variation in sorghum fodder yield, nutrient uptake and post-harvest soil fertility status for available N, P and K in different plots confirming the establishment of soil fertility gradient for the respective nutrients. The establishment of soil fertility gradient is necessary and serves as a pre-requisite for developing improved nutrient management strategies i.e. STCR-based fertilizer recommendations to sustain crop yield and optimize fertilizer requirements.

Site-Specific Mehlich 3-P Recommendations for Florida’s Sandy Soils

ABSTRACT In 2010, the Mehlich 3 (M3) soil extractant replaced Mehlich 1 (M1) as the official soil test for Florida. While a linear expression was initially established to reasonably estimate M3-P values based on M1-P recommendations for acid-mineral soils in Florida, Florida farmers have been skeptical of revised P recommendations and reported lower yields when following them, suggesting that adjustments to recommended P fertilizer application rates may be needed. This study evaluated different extraction protocols to estimate bioavailable P in major agricultural mineral soil orders, predominant in Florida. Extractions were conducted on 420 surface samples for M1- and M3-P and on 123 samples for FeO (iron oxide impregnated strip), Haney H3A, and anion exchange resin membrane (AERM). Our findings suggest that the current P fertilizer recommendations, which rely on the M1-P to M3-P linear relationship, may underestimate agronomic thresholds for both low and high P levels. The variability in P extraction by FeO compared to M3 appears to be site-specific and could explain yield differences observed with M3 testing. While promising, our revised P recommendations need further validation through additional yield response analyses across various locations to improve the accuracy of predicting crop yields based on soil P values.

Predicting soil properties for fertiliser recommendation in South Korea using MIR spectroscopy

The national fertiliser policies in South Korea aim to provide guidance to farmers for efficient fertiliser application and thus rely on the annual collection and analysis of soil samples. Providing timely soil analysis results remains a challenge, as wet laboratory analysis is time-consuming and expensive. This study represents a pioneering effort in South Korea, by investigating mid-infrared (MIR) spectroscopy for accurate soil properties prediction and its application in developing fertiliser recommendations for several crop types. Additionally, we examined the time efficiency of MIR spectroscopy compared to conventional analytical methods. A total of 567 soil samples from diverse soil and land use types (paddy, upland, orchard, and greenhouse fields) in South Korea (0–20 cm depth) were collected and scanned using an MIR spectrometer. Four machine learning algorithms (partial least squares regression, support vector machine, cubist, and random forest) were trialled and compared for their prediction accuracies using 15-fold cross-validation for eight essential soil properties: organic matter, total nitrogen (N), available phosphorus (P), pH, exchangeable calcium (Ca), potassium (K), magnesium (Mg), and available silica. Results demonstrated robust predictive performance (R2 > 0.70) across the selected soil properties, with organic matter and total nitrogen exhibiting excellent accuracy (R2 > 0.9). Compared with conventional analysis, the average difference in fertiliser application recommendation for seven crops using MIR prediction was 3.8 % for N, 13.9 % for P and 8.1 % for K. Based on the measurement of 11 soil properties, analysis using MIR spectroscopy was about 12 times faster than conventional methods. The study demonstrates the potential of this approach to revolutionise soil analysis protocols, offering a more efficient and cost-effective solution for sustainable agricultural practices in South Korea.

Evaluating soils phosphorus forms and distribution under different land use types

Abstract. Following nitrogen (N), phosphorus (P) is the second most important macronutrient for plant and microorganism development. Phosphorus is found in nucleic acids, phospholipids, and ATP and is required for energy transmission and cell structure. Phosphorus is also essential for biomass accumulation and primary productivity. However, it is often present in low availability forms in the extensively worn soils of tropical and subtropical regions, which has been considered one of the key limiting factors for agricultural output. Hence, the reason for this research being carried out. A total of 24 soil samples were collected from four different land uses at depths 0-15 cm and 15-30 cm, respectively, within the Kogi State University area of Anyigba with the aim of evaluating the effects of land on forms and distributions of phosphorus. The study was a 4 × 3 × 2 factorial experiment laid out in a Randomized Complete Block Design. Available P, total organic P, total inorganic P, inorganic P fractions (Fe-P, Ca-P, Al-P, Red-P and Occ/Fe-Al-P) analyses were carried out using standard procedures. The data from the laboratory analyses were subjected to three-way analysis of variance, and the means between treatments were separated using Tukey's test with a 5 % probability. The results revealed that the soils contained low levels of available P. The soil beneath forest land had the highest available P concentration (10.92 mg/kg), whereas the lowest was found in cultivated land (8.97 mg/kg). The P forms declined with depths. According to the findings, Fe-P had the highest amounts of inorganic P fractions in the research area. Lower P concentrations in cultivated land were related to lower organic matter content caused by continuous crops cultivation on the soil. Phosphorus fractions investigations are thus advised in cultivated soils to provide an adequate understanding of P status in the soil and fertilizer recommendations to boost productivity.

Comparison of conventional methods with Haney H3A version 4 for available phosphorus and potassium in southern Manitoba soils

The H3A-4 extraction is a new method to determine plant available nutrients but has not been compared with standard soil tests or calibrated to crop response in Manitoba, Canada. Olsen P and ammonium acetate K were related to H3A-4 P and K for 961 soil samples. Significant relations were found between Olsen P and H3A-4 ( R2 = 0.74, P < 0.01) and ammonium acetate K and H3A-4 ( R2 = 0.83, P < 0.01). New thresholds were established for fertilizer recommendations with H3A-4 as 24 mg kg–1 for P and 32 mg kg–1 for K.

When should wheat phosphorus recommendations be based on build‐maintenance rather than sufficiency? An economic analysis

AbstractThis article presents an economic analysis of two phosphorus (P) fertilizer recommendation approaches, sufficiency and build‐maintenance, in the context of Kansas and Oklahoma wheat (Triticum aestivum L.). Sufficiency seeks to meet crop needs rather than build soil fertility. Build‐maintenance, however, builds P levels to a target level of soil test phosphorus (STP) and then maintains that level by replacing the P removed by the crop. The Oklahoma and Kansas sufficiency approaches recommend less P than their build‐maintenance alternatives. The research objective was to determine when one approach is preferred over the other. Through dynamic simulation, the net present value (NPV) of these two alternatives was estimated under alternative scenarios. A meta‐analysis of previous experiments supported the assumption that with Mehlich‐3 STP levels of 15 mg kg‒1, yield would be 90% of maximum yield even when the recommended sufficiency levels were applied. The estimate from the meta‐analysis was a 9% yield loss, and the null hypothesis of no yield loss was rejected (p < 0.0001). The scenarios considered varied initial STP, yield potential, and prices. Sufficiency had a higher NPV under almost all 4‐year planning horizons. With a longer 20‐year planning horizon, build‐maintenance was always preferred. With an 8‐year planning horizon, the preferred system varied depending on assumptions with build‐maintenance preferred more often. The finding of build maintenance being more competitive in the long run should hold for other crops and locations using approaches like those in Oklahoma and Kansas.