Abstract

Phosphorus (P) is an essential element that plays an important role in carbohydrate metabolism and energy transfer systems in all plants. Sufficient P supply is therefore essential for providing adequate food, fibre and fuel for society. In potato, P deficiency reduces yield and tuber number due to reduced radiation interception by the canopy. Phosphorus is a limited, non-renewable resource. When lost to water bodies, P causes environmental problems such as eutrophication. Potato fields may be a significant contributor to P loads to water due to high P recommendations and a tendency for P leaching in soils where the P sorption/binding capacity is saturated. Efficient use of P in potato cultivation is therefore crucial in order to reduce P consumption and environmental impacts. The thesis improves the current understanding of potato P requirements as regards optimising P application strategies, use efficiency and potato tuber yield. The results show that split P applications can improve P recovery by 25%, particularly on soils with low P content and low buffering capacity, and can improve physiological P use efficiency (PPUE) where P availability is limiting yield. Irrigation and subsoiling can both significantly improve P recovery, PPUE and yield. Foliar application does not improve PPUE, but can increase P concentration and yield if the plant is supplied with sufficient water. However, foliar P application should not be used as a general strategy, but can be recommended where the soil buffering capacity is extremely high. It is shown in this thesis that many Swedish soils contain sufficient amounts of P to support optimal growth and are no longer responsive to P fertilization. To determine the responsiveness of potato yields to P, data on soil organic material, pH, soil buffering capacity and varietal characteristics are needed, in addition to the amount of P-extractable with ammonium lactate (P-AL value) used in Sweden today. More sophisticated P recommendation models which take these parameters into account are urgently needed. As long as yield effects from P fertilization cannot be predicted, excessive P fertilization will probably continue, resulting in waste of a non-renewable resource, eutrophication of the aquatic environment and reduced farm profits. The findings in this thesis contribute to understanding the complex picture of P acquisition in potato and, hopefully, to more efficient use of the non-renewable P resource.

Keywords

Inter-row subsoiling; irrigation; starch yield; phosphorus use efficiency; foliar fertilization; phosphate; P-AL; buffering capacity; sorption; Solanum tuberosum

Published in

Acta Universitatis Agriculturae Sueciae
2014, number: 2014:61
ISBN: 978-91-576-8070-9, eISBN: 978-91-576-8071-6
Publisher: Department of Biosystems and Technology, Swedish University of Agricultural Sciences

SLU Authors

• Ekelöf, Joakim

  • Department of Biosystems and Technology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Soil Science
Agricultural Science


Permanent link to this page (URI)

https://res.slu.se/id/publ/60112