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In this paper, a cylindrical capacitance sensor was designed based on the dielectric properties of the fertilizer solution, and an online rapid detection method of fertilizer type and concentration was proposed based on the characteristic frequency response mode. Three fertilizer solutions, potassium chloride, calcium superphosphate, and urea, were used as test objects. Ten concentrations of each fertilizer solution in the 10~100 g\/L range were taken as the test fertilizer solution. Then, under the action of a series of sine wave excitation signals from 1 kHz to 10 MHz, the sensor\u2019s amplitude-frequency\/phase-frequency response data were obtained. The detection strategy of \u2018first type, then concentration\u2019 was adopted to realize rapid online detection of fertilizer type and concentration. Experimental results indicated that the maximum relative error of the sensor stability test was 0.72%, and the maximum error of concentration detection was 7.26%. Thus, the intelligent water and fertilizer machine can give feedback on the information of a fertilizer solution in real-time during the process of precise variable fertilization, thus improving the intelligence of water and fertilizer machines.<\/jats:p>","DOI":"10.3390\/s23031116","type":"journal-article","created":{"date-parts":[[2023,1,19]],"date-time":"2023-01-19T01:33:51Z","timestamp":1674092031000},"page":"1116","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Online Rapid Detection Method of Fertilizer Solution Information Based on Characteristic Frequency Response Features"],"prefix":"10.3390","volume":"23","author":[{"given":"Jianian","family":"Li","sequence":"first","affiliation":[{"name":"Faculty of Modern Agricultural Engineering, Kunming University of Science and Technology, Kunming 650500, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7197-713X","authenticated-orcid":false,"given":"Yuan","family":"Gao","sequence":"additional","affiliation":[{"name":"Faculty of Modern Agricultural Engineering, Kunming University of Science and Technology, Kunming 650500, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jingyuan","family":"Zeng","sequence":"additional","affiliation":[{"name":"Guangdong Provincial Key Laboratory of Conservation and Precision Utilization of Characteristic Agricultural Resources in Mountainous Areas, College of Computer Science, Jiaying University, Meizhou 514015, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xing","family":"Li","sequence":"additional","affiliation":[{"name":"Faculty of Modern Agricultural Engineering, Kunming University of Science and Technology, Kunming 650500, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhuoyuan","family":"Wu","sequence":"additional","affiliation":[{"name":"Faculty of Modern Agricultural Engineering, Kunming University of Science and Technology, Kunming 650500, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Guoxuan","family":"Wang","sequence":"additional","affiliation":[{"name":"Faculty of Modern Agricultural Engineering, Kunming University of Science and Technology, Kunming 650500, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,1,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"65","DOI":"10.1007\/s11442-022-1936-2","article-title":"Chemical fertilizer rate, use efficiency and reduction of cereal crops in China, 1998\u20132018","volume":"32","author":"Xin","year":"2022","journal-title":"J. Geogr. Sci."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"107489","DOI":"10.1016\/j.agwat.2022.107489","article-title":"Improving wheat yield by optimizing seeding and fertilizer rates based on precipitation in the summer fallow season in drylands of the Loess Plateau","volume":"264","author":"Qiu","year":"2022","journal-title":"Agric. Water Manag."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"88","DOI":"10.2134\/agronj1973.00021962006500010027x","article-title":"Role of pensacola bahiagrass stolon-root system in fertilizer nitrogen utilization on leon fine sand","volume":"65","author":"Blue","year":"1973","journal-title":"Agron. J."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"8338","DOI":"10.3390\/s120608338","article-title":"A miniature integrated multimodal sensor for measuring Ph, Ec and temperature for precision agriculture","volume":"12","author":"Futagawa","year":"2012","journal-title":"Sensors"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"227","DOI":"10.1016\/S0304-4238(99)00058-8","article-title":"Sensory analysis, sugar and acid content of tomato at different Ec values of the nutrient solution","volume":"82","author":"Auerswald","year":"1999","journal-title":"Sci. Hortic."},{"key":"ref_6","unstructured":"(2022, September 30). Fertigation Solutions for Every Application. Available online: https:\/\/www.netafimusa.com\/agriculture\/digital-farming\/netbeat\/fertigation\/."},{"key":"ref_7","unstructured":"(2022, September 30). Priva Nutri-Line: Perfect Fertigation for Healthy Crops. Available online: https:\/\/www.priva.com\/horticulture\/solutions\/priva-nutri-line."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"751","DOI":"10.1039\/an9709500751","article-title":"Analysis of plants, soils and waters for nitrate by using an ion-selective electrode","volume":"95","author":"Milham","year":"1970","journal-title":"Analyst"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1016\/j.compag.2018.01.019","article-title":"On-site ion monitoring system for precision hydroponic nutrient management","volume":"146","author":"Cho","year":"2018","journal-title":"Comput. Electron. Agric."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"141","DOI":"10.12791\/KSBEC.2020.29.2.141","article-title":"Real-time nutrient monitoring of hydroponic solutions using an ion-selective electrode-based embedded system","volume":"29","year":"2020","journal-title":"Prot. Hortic. Plant Fact."},{"key":"ref_11","first-page":"139","article-title":"Development of real-time detecting device for nitrogen concentration of liquid fertilizer","volume":"31","author":"Li","year":"2015","journal-title":"Trans. Chin. Soc. Agric. Eng."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"121110","DOI":"10.1016\/j.talanta.2020.121110","article-title":"An electronic tongue for simultaneous determination of Ca2+, Mg2+, K+ and NH4+ in water samples by multivariate calibration methods","volume":"217","author":"Atas","year":"2020","journal-title":"Talanta"},{"key":"ref_13","first-page":"200","article-title":"ISE modeling of hydroponic formula based on biplot method difference analysis","volume":"50","author":"Zhang","year":"2019","journal-title":"Trans. Chin. Soc. Agric. Mach."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"4439","DOI":"10.1038\/s41598-019-38695-4","article-title":"Soil moisture and nitrate-nitrogen dynamics and economic yield in the greenhouse cultivation of tomato and cucumber under negative pressure irrigation in the North China Plain","volume":"9","author":"Li","year":"2019","journal-title":"Sci. Rep."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1504","DOI":"10.21273\/HORTSCI.40.5.1504","article-title":"Determination of optimum fertilizer concentration and corresponding substrate electrical conductivity for ten taxa of herbaceous perennials","volume":"40","author":"Scoggins","year":"2005","journal-title":"Hortscience"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"195","DOI":"10.1097\/00010694-199203000-00004","article-title":"Effect of cropping systems on adsorption of metals by soils: II. Effect of Ph","volume":"153","author":"Basta","year":"1992","journal-title":"Soil Sci."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"412","DOI":"10.1007\/s13580-013-0068-0","article-title":"Uptake of Nutrients and Water by Paprika (Capsicum annuum L.) as Affected by Renewal Period of Recycled Nutrient Solution in Closed Soilless Culture","volume":"54","author":"Ko","year":"2013","journal-title":"Hortic. Environ. Biotechnol."},{"key":"ref_18","first-page":"462","article-title":"Virtual Ion Selective Electrode for Online Measurement of Nutrient Solution Components","volume":"11.2","author":"Chen","year":"2010","journal-title":"IEEE Sens. J."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"129","DOI":"10.1016\/0021-8634(88)90110-2","article-title":"Monitoring nutrient film solutions using ion-selective electrodes","volume":"40","author":"Bailey","year":"1988","journal-title":"J. Agric. Eng. Res."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"711","DOI":"10.1166\/sl.2015.3515","article-title":"Ionophores contribution in making of ion selective electrodes: A review","volume":"13","author":"Swami","year":"2015","journal-title":"Sens. Lett."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"340008","DOI":"10.1016\/j.aca.2022.340008","article-title":"A hybrid conductometric\/spectrophotometric method for determining ionic strength of dilute aqueous solutions","volume":"1220","author":"Schockman","year":"2022","journal-title":"Analytica Chimica Acta"},{"key":"ref_22","first-page":"89","article-title":"An optofluidic dye concentration detector based on the pulsed photoacoustic effect","volume":"Volume 11637","author":"Roy","year":"2021","journal-title":"Microfluidics, BioMEMS, and Medical Microsystems XIX"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"131355","DOI":"10.1016\/j.snb.2021.131355","article-title":"Multiplex sensing of complex mixtures by machine vision analysis of TLC-SERS images","volume":"357","author":"Hou","year":"2022","journal-title":"Sens. Actuators B Chem."},{"key":"ref_24","first-page":"31","article-title":"Development of Liquid Concentration On - line Detection Device Based on Light Transmission Method","volume":"44","author":"Hu","year":"2022","journal-title":"J. Agric. Mech. Res."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"196","DOI":"10.1016\/j.triboint.2019.05.025","article-title":"A multi-function sensor for online detection of contaminants in hydraulic oil","volume":"138","author":"Shi","year":"2019","journal-title":"Tribol. Int."},{"key":"ref_26","first-page":"171","article-title":"Dielectric frequency response of oil-paper composite insulation with transient moisture equilibrium","volume":"33","author":"Liu","year":"2013","journal-title":"Proc. CSEE"},{"key":"ref_27","first-page":"64","article-title":"The measurement of the dielectric properties of NaCl solution and seawater samples","volume":"2","author":"Chu","year":"1980","journal-title":"J. East China Norm. Univ. (Nat. Sci.)"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"17","DOI":"10.1007\/BF02708605","article-title":"Dielectric properties of solution-grown-undoped and acrylic-acid-doped ethly cellulose","volume":"23","author":"Khare","year":"2000","journal-title":"Bull. Mater. Sci."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"116295","DOI":"10.1016\/j.molliq.2021.116295","article-title":"The effect of macromolecular crowders on dielecric constant of aqueous electrolyte solutions","volume":"336","author":"Slejko","year":"2021","journal-title":"J. Mol. Liq."},{"key":"ref_30","first-page":"124","article-title":"Detection of sylvine concentration in water based on permittivity","volume":"28","author":"Xi","year":"2012","journal-title":"Trans. Chin. Soc. Agric. Eng."},{"key":"ref_31","first-page":"157","article-title":"Pressure and temperature dependence of the dielectric properties in the perovskite solution of Gd-doped barium titanate","volume":"17","author":"Kim","year":"1998","journal-title":"J. Mater. Sci. Lett."},{"key":"ref_32","unstructured":"Wang, J.W., and Fu, W.B. (2005). Analyses of amplitude-frequency and phase-frequency characteristics of 3dB bridges. J. Air Force Radar Acad., 24\u201327. (In Chinese)."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"111","DOI":"10.5194\/hess-2-111-1998","article-title":"The dielectric calibration of capacitance probes for soil hydrology using an oscillation frequency response model","volume":"2","author":"Robinson","year":"1998","journal-title":"Hydrol. Earth Syst. Sci."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"225","DOI":"10.1007\/BF00119439","article-title":"Concentration fluctuation measurements in tracer plumes using high and low frequency response detectors","volume":"79","author":"Mylne","year":"1996","journal-title":"Bound. Layer Meteorol."},{"key":"ref_35","first-page":"91","article-title":"Design and experiment of concentric cylindrical capacitive sensor for liquid fertilizer concentration","volume":"37","author":"Ma","year":"2018","journal-title":"Transducer Microsyst. Technol."},{"key":"ref_36","first-page":"49","article-title":"Calculation of the capacitance of the cylindrical capacitor with arbitrary dimensions","volume":"19","author":"Jiang","year":"2005","journal-title":"J. Electron. Meas. Instrum."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"75","DOI":"10.1007\/BF00991766","article-title":"Active devices in precision bridge circuits","volume":"6","author":"Grin","year":"1963","journal-title":"Meas. Tech."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"89","DOI":"10.1063\/1.1751493","article-title":"A null detector for A.C. bridge measurements","volume":"10","author":"Binns","year":"1939","journal-title":"Rev. Sci. Instrum."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"155","DOI":"10.1016\/j.vlsi.2011.01.003","article-title":"High-speed full adder based on minority function and bridge style for nanoscale","volume":"44","author":"Navi","year":"2011","journal-title":"Integration"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/3\/1116\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T18:09:13Z","timestamp":1760119753000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/3\/1116"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,1,18]]},"references-count":39,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2023,2]]}},"alternative-id":["s23031116"],"URL":"https:\/\/doi.org\/10.3390\/s23031116","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,1,18]]}}}