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dc.contributor.authorCampkin, Roger
dc.date.accessioned2016-08-28T22:44:07Z
dc.date.available2016-08-28T22:44:07Z
dc.date.issued1972
dc.identifier.urihttps://hdl.handle.net/10182/7277
dc.description.abstractThe availability of potassium to pasture plants in New Zealand is dependent upon the mineralogy of the soil in many ways. It will depend first of all on the primary minerals present, mostly in the sand and the silt fraction of the soil, however, equally important is the amount and type of secondary clay minerals formed during pedogenesis. These minerals will govern the distribution of soil potassium into forms which are unavailable, potentially available and readily available to plants. For a soil under grazed pasture other important sources of available potassium are additions to the soil surface in fertilizer and/or in animal urine and dung. Where suitable clay minerals are present in the soil there may be a considerable release of potassium into a readily available form as this form is lowered by plant uptake. Some clay minerals may also convert any excess of available potassium into less available forms by the process of potassium fixation. This fixation may be beneficial if it decreases losses of soluble potassium due to leaching or to luxury uptake by plants, especially after top dressing or urine applications. For pastoral farming in New Zealand, exchangeable potassium is used as a guide to plant available potassium and is also related to dry matter responses to potassium in observational field trials, (Hogg, 1957). The aim of this study is to relate the availability of potassium to ryegrass, a major user of potassium in the pasture system, to the clay mineralogy of two sequences of New Zealand soils. In addition, the effect of clay mineralogy on the release and fixation of potassium by these soils is studies. Changes in soil potassium and clay mineralogy of both zonal and ash soils with increasing soil development are discussed.en
dc.language.isoenen
dc.publisherLincoln College, University of Canterburyen
dc.rights.urihttps://researcharchive.lincoln.ac.nz/page/rights
dc.subjectnutrientsen
dc.subjectpotassiumen
dc.subjectsoil fertilityen
dc.subjectsoil chemistryen
dc.subjectpasture soilen
dc.subjectryegrassen
dc.subjectclaysen
dc.subjectexchangeable Ken
dc.titlePotassium release and fixation by some New Zealand soils as related to their clay mineralogy and degree of profile developmenten
dc.typeThesisen
thesis.degree.grantorUniversity of Canterburyen
thesis.degree.levelMastersen
thesis.degree.nameMaster of Agricultural Scienceen
lu.thesis.supervisorWalker, T. W.
lu.contributor.unitDepartment of Soil and Physical Sciencesen
dc.rights.accessRightsDigital thesis can be viewed by current staff and students of Lincoln University only. Print copy available for reading in Lincoln University Library. May be available through inter-library loan.en
dc.subject.anzsrc070306 Crop and Pasture Nutritionen
dc.subject.anzsrc050304 Soil Chemistry (excl. Carbon Sequestration Science)en


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