{"id":{"repo_id":"byu","oai_identifier":"oai:scholarsarchive.byu.edu:etd-1940"},"canonical_url":"https://search.dev.ndltd.org/etd/byu/oai:scholarsarchive.byu.edu:etd-1940","repository":{"repo_id":"byu","name":"Brigham Young University","base_url":"https://scholarsarchive.byu.edu/do/oai/"},"display":{"title":"Predicting Maize Yield, Nutrient Concentration and Uptake in P and K Fertilized Soils: Pressurized Hot Water and Other Alternatives to Mehlich I Extraction in Guatemala Soils","abstract":"The inaccessibility and cost of soil testing reduce effectiveness of fertilizer use on small-scale subsistence farms, and inadequate funding promotes adoption of soil tests in developing countries with minimal validation. For example, Mehlich-I extraction of phosphorus (P) currently used extensively in Guatemala may not be suitable for its broad range of soils. At least four alternatives are available but are relatively untested [Bray 1, Mehlich III, Olsen and pressurized hot water (PHW)]. Pressurized hot water is relatively simple and inexpensive, but is not yet tested against other extraction methods under variable P or potassium (K) fertilization levels. To determine whether PHW-extracted nutrients could be used to predict maize yield, as nutrient content and uptake, soil, plant tissue and grain samples were obtained from a multiple-site field study and calibration studies were conducted using five rates of P and three rates of K on soils incubated without plants or cropped with maize in greenhouse and field conditions. In the multiple-site field study, maize yield related significantly to PHW-extractable P (r2=0.36) and to leaf P concentration (r2=0.23), but Mehlich I did not. In the two soils used in the greenhouse study, maize yield, vegetative P concentration and total P uptake by maize were predicted by PHW extractable P (R2=0.72, 0.75 and 0.90, respectively). In the field experiment, grain yield was not improved by P or K application, but P content of maize leaf tissue did relate significantly with PHW-extracted P (R2=0.40), but Mehlich I did not. There were no yield responses to K application in any experiment, but relationships defined between extractable K for all five K-extraction procedures and soil applied K were similarly significant. In comparing P extraction methods, PHW was as good as or better than Olsen, Bray 1 and Mehlich III for relating soil P extraction to the parameters measured in these experiments, and these four alternative extraction methods were consistently better than Mehlich I. Mehlich I extraction should be replaced by one of the four alternatives tested, and PHW is the least expensive and, thus, most viable for use in Guatemala soils.","abstract_html":"The inaccessibility and cost of soil testing reduce effectiveness of fertilizer use on small-scale subsistence farms, and inadequate funding promotes adoption of soil tests in developing countries with minimal validation. For example, Mehlich-I extraction of phosphorus (P) currently used extensively in Guatemala may not be suitable for its broad range of soils. At least four alternatives are available but are relatively untested [Bray 1, Mehlich III, Olsen and pressurized hot water (PHW)]. Pressurized hot water is relatively simple and inexpensive, but is not yet tested against other extraction methods under variable P or potassium (K) fertilization levels. To determine whether PHW-extracted nutrients could be used to predict maize yield, as nutrient content and uptake, soil, plant tissue and grain samples were obtained from a multiple-site field study and calibration studies were conducted using five rates of P and three rates of K on soils incubated without plants or cropped with maize in greenhouse and field conditions. In the multiple-site field study, maize yield related significantly to PHW-extractable P (r2=0.36) and to leaf P concentration (r2=0.23), but Mehlich I did not. In the two soils used in the greenhouse study, maize yield, vegetative P concentration and total P uptake by maize were predicted by PHW extractable P (R2=0.72, 0.75 and 0.90, respectively). In the field experiment, grain yield was not improved by P or K application, but P content of maize leaf tissue did relate significantly with PHW-extracted P (R2=0.40), but Mehlich I did not. There were no yield responses to K application in any experiment, but relationships defined between extractable K for all five K-extraction procedures and soil applied K were similarly significant. In comparing P extraction methods, PHW was as good as or better than Olsen, Bray 1 and Mehlich III for relating soil P extraction to the parameters measured in these experiments, and these four alternative extraction methods were consistently better than Mehlich I. Mehlich I extraction should be replaced by one of the four alternatives tested, and PHW is the least expensive and, thus, most viable for use in Guatemala soils.","abstract_has_math":false,"creators":["Hunsaker, Heather Mae"],"institution":"Brigham Young University - Provo","degree_name":"MS","degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":null,"date_issued":"","date_published":null,"updated_at":"2026-07-24T01:28:37Z","subjects":["soil test phosphorus","small-scale agriculture","subsistence farming","Guatemala","Mehlich I","Mehlich III","Olsen","pressurized hot water","Bray-1","maize","corn","international agriculture","Animal Sciences"],"languages":["English"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholarsarchive.byu.edu/etd/941","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Hunsaker, Heather Mae"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2006-07-26T07:00:00Z"]},{"key":"dc:publisher","label":"Institution","values":["Brigham Young University - Provo"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["MS"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["soil test phosphorus","small-scale agriculture","subsistence farming","Guatemala","Mehlich I","Mehlich III","Olsen","pressurized hot water","Bray-1","maize","corn","international agriculture","Animal Sciences"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["English"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholarsarchive.byu.edu/etd/941","https://scholarsarchive.byu.edu/context/etd/article/1940/viewcontent/ETD_CISOPTR_1064.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Life Sciences; Plant and Wildlife Sciences","Biology and Agriculture;Plant and Animal Sciences"]},{"key":"dc:description.abstract","label":"Abstract","values":["The inaccessibility and cost of soil testing reduce effectiveness of fertilizer use on small-scale subsistence farms, and inadequate funding promotes adoption of soil tests in developing countries with minimal validation. For example, Mehlich-I extraction of phosphorus (P) currently used extensively in Guatemala may not be suitable for its broad range of soils. At least four alternatives are available but are relatively untested [Bray 1, Mehlich III, Olsen and pressurized hot water (PHW)]. Pressurized hot water is relatively simple and inexpensive, but is not yet tested against other extraction methods under variable P or potassium (K) fertilization levels. To determine whether PHW-extracted nutrients could be used to predict maize yield, as nutrient content and uptake, soil, plant tissue and grain samples were obtained from a multiple-site field study and calibration studies were conducted using five rates of P and three rates of K on soils incubated without plants or cropped with maize in greenhouse and field conditions. In the multiple-site field study, maize yield related significantly to PHW-extractable P (r2=0.36) and to leaf P concentration (r2=0.23), but Mehlich I did not. In the two soils used in the greenhouse study, maize yield, vegetative P concentration and total P uptake by maize were predicted by PHW extractable P (R2=0.72, 0.75 and 0.90, respectively). In the field experiment, grain yield was not improved by P or K application, but P content of maize leaf tissue did relate significantly with PHW-extracted P (R2=0.40), but Mehlich I did not. There were no yield responses to K application in any experiment, but relationships defined between extractable K for all five K-extraction procedures and soil applied K were similarly significant. In comparing P extraction methods, PHW was as good as or better than Olsen, Bray 1 and Mehlich III for relating soil P extraction to the parameters measured in these experiments, and these four alternative extraction methods were consistently better than Mehlich I. Mehlich I extraction should be replaced by one of the four alternatives tested, and PHW is the least expensive and, thus, most viable for use in Guatemala soils."]},{"key":"dc:format","label":"Dc Format","values":["application:pdf"]},{"key":"dc:source","label":"Dc Source","values":["Brigham Young University - Provo"]},{"key":"dc:title","label":"Title","values":["Predicting Maize Yield, Nutrient Concentration and Uptake in P and K Fertilized Soils: Pressurized Hot Water and Other Alternatives to Mehlich I Extraction in Guatemala Soils"]}]}],"canonical_facts":{"dc:creator":["Hunsaker, Heather Mae"],"dc:date":["2006-07-26T07:00:00Z"],"dc:description":["Life Sciences; Plant and Wildlife Sciences","Biology and Agriculture;Plant and Animal Sciences"],"dc:description.abstract":["The inaccessibility and cost of soil testing reduce effectiveness of fertilizer use on small-scale subsistence farms, and inadequate funding promotes adoption of soil tests in developing countries with minimal validation. For example, Mehlich-I extraction of phosphorus (P) currently used extensively in Guatemala may not be suitable for its broad range of soils. At least four alternatives are available but are relatively untested [Bray 1, Mehlich III, Olsen and pressurized hot water (PHW)]. Pressurized hot water is relatively simple and inexpensive, but is not yet tested against other extraction methods under variable P or potassium (K) fertilization levels. To determine whether PHW-extracted nutrients could be used to predict maize yield, as nutrient content and uptake, soil, plant tissue and grain samples were obtained from a multiple-site field study and calibration studies were conducted using five rates of P and three rates of K on soils incubated without plants or cropped with maize in greenhouse and field conditions. In the multiple-site field study, maize yield related significantly to PHW-extractable P (r2=0.36) and to leaf P concentration (r2=0.23), but Mehlich I did not. In the two soils used in the greenhouse study, maize yield, vegetative P concentration and total P uptake by maize were predicted by PHW extractable P (R2=0.72, 0.75 and 0.90, respectively). In the field experiment, grain yield was not improved by P or K application, but P content of maize leaf tissue did relate significantly with PHW-extracted P (R2=0.40), but Mehlich I did not. There were no yield responses to K application in any experiment, but relationships defined between extractable K for all five K-extraction procedures and soil applied K were similarly significant. In comparing P extraction methods, PHW was as good as or better than Olsen, Bray 1 and Mehlich III for relating soil P extraction to the parameters measured in these experiments, and these four alternative extraction methods were consistently better than Mehlich I. Mehlich I extraction should be replaced by one of the four alternatives tested, and PHW is the least expensive and, thus, most viable for use in Guatemala soils."],"dc:format":["application:pdf"],"dc:identifier":["https://scholarsarchive.byu.edu/etd/941","https://scholarsarchive.byu.edu/context/etd/article/1940/viewcontent/ETD_CISOPTR_1064.pdf"],"dc:language":["English"],"dc:publisher":["Brigham Young University - Provo"],"dc:source":["Brigham Young University - Provo"],"dc:subject":["soil test phosphorus","small-scale agriculture","subsistence farming","Guatemala","Mehlich I","Mehlich III","Olsen","pressurized hot water","Bray-1","maize","corn","international agriculture","Animal Sciences"],"dc:title":["Predicting Maize Yield, Nutrient Concentration and Uptake in P and K Fertilized Soils: Pressurized Hot Water and Other Alternatives to Mehlich I Extraction in Guatemala Soils"],"dc:type":["Thesis"],"thesis:degree_name":["MS"]},"updated_at":"2026-07-24T01:28:37Z"}