{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,3]],"date-time":"2026-09-03T18:14:51Z","timestamp":1788459291946,"version":"build-2803163510"},"reference-count":43,"publisher":"Public Library of Science (PLoS)","issue":"9","license":[{"start":{"date-parts":[[2026,9,3]],"date-time":"2026-09-03T00:00:00Z","timestamp":1788393600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"<jats:p>\n                    Liquid organic fertilizers (LOF) are used to supply additional nutrients to crops. However, LOF are expensive to use regularly. In this research, a smart fertigation treatment (S), where LOF was applied based on lettuce plant growth, was compared to a manual treatment (M) in a greenhouse. Digital sensors with IoT capability were installed in S and M treatments. The sensor in S treatment was interfaced to a solid-state relay connected to a pump, to automatically regulate LOF application. Digital sensors in both treatments measured canopy area (CA) of plants once every three days using image analysis and remotely exchanged data. In the M treatment, LOF was applied every third day to plants, whereas the LOF application was regulated by the sensor in S treatment to happen only when CA of plants was lower by 10% than those in the M treatment. Results indicated no differences in fresh weight (33.4 vs. 32.3 g\u00b7plant\n                    <jats:sup>\u22121<\/jats:sup>\n                    ) and leaf area (770.2 and 772.6 cm\n                    <jats:sup>\u22122<\/jats:sup>\n                    ) of plants between two treatments. Nutrient concentration in the root zone, measured as electrical conductivity of substrate, was significantly higher (21\u201369%) in M than S treatment. The number of fertigation events and cost of LOF applied were approximately four times higher in M than S treatment. This resulted in higher fertilizer-use-efficiency in S (1.159 kg\u2009\u2219\u2009m\n                    <jats:sup>\u22122<\/jats:sup>\n                    \u2009\u2219\u2009$\n                    <jats:sup>\u22121<\/jats:sup>\n                    ) than M (0.168 kg\u2009\u2219\u2009m\n                    <jats:sup>\u22122<\/jats:sup>\n                    \u2009\u2219\u2009$\n                    <jats:sup>\u22121<\/jats:sup>\n                    ) treatment. These results indicate that the smart fertigation method can optimize LOF application (i.e., reduce wastage and costs) while maintaining crop growth.\n                  <\/jats:p>","DOI":"10.1371\/journal.pone.0357482","type":"journal-article","created":{"date-parts":[[2026,9,3]],"date-time":"2026-09-03T17:29:51Z","timestamp":1788456591000},"page":"e0357482","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":0,"title":["Smart fertigation: Automated fertilizer application based on plant growth using digital sensors with IoT capability"],"prefix":"10.1371","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8460-0921","authenticated-orcid":true,"given":"Sangrak","family":"Son","sequence":"first","affiliation":[{"name":"Horticulture and Landscape Architecture, Purdue University","place":["West Lafayette, Indiana, United States of America"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jin","family":"Wei-Kocsis","sequence":"additional","affiliation":[{"name":"Polytechnic Institute, Purdue University","place":["West Lafayette, Indiana, United States of America"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Amanda","family":"Deering","sequence":"additional","affiliation":[{"name":"Food Science, Purdue University","place":["West Lafayette, Indiana, United States of America"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lori","family":"Hoagland","sequence":"additional","affiliation":[{"name":"Horticulture and Landscape Architecture, Purdue University","place":["West Lafayette, Indiana, United States of America"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2443-8707","authenticated-orcid":true,"given":"Krishna","family":"Nemali","sequence":"additional","affiliation":[{"name":"Horticulture and Landscape Architecture, Purdue University","place":["West Lafayette, Indiana, United States of America"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2026,9,3]]},"reference":[{"issue":"4","key":"pone.0357482.ref001","doi-asserted-by":"crossref","first-page":"369","DOI":"10.1007\/s40093-019-0257-7","article-title":"Liquid organic fertilizer production for growing vegetables under hydroponic condition","volume":"8","author":"T Phibunwatthanawong","year":"2019","journal-title":"Int J Recycl Org Waste Agricult"},{"issue":"5","key":"pone.0357482.ref002","doi-asserted-by":"crossref","first-page":"1329","DOI":"10.3390\/agronomy13051329","article-title":"Optimizing organic carrot (daucus carota var. sativus) yield and quality using fish emulsions, cyanobacterial fertilizer, and seaweed extracts","volume":"13","author":"A 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