Nutrient cycling in agroecosystems: nitrogen cycling in southern Sweden in the 1850s and two Tanzanian villages in the 1990s

Lars-Erik Williams

Research output: ThesisDoctoral Thesis (monograph)

Abstract

This study presents a general model for analysing nutrient cycling in agroecosystems. The focus is on food production intensity, human carrying capacity, sustainability and efficiency. The model can be used on systems including different kinds of land uses, which makes it applicable for studies on different scales. Comparisons of all kinds of agroecosystems, independent of time and place, are made possible. Different kinds of nutrients can be studied with the model. Here, nitrogen cycling is used as an example. A region in Scania, southern Sweden, 1858, and two Tanzanian villages, 1989-91, are analysed. The book includes a discussion of ecological principles of how humans can increase their food production, based on nutrient cycling and with concrete examples. Main conclusions in the thesis are: - There exists a conflict between increase of food production and sustainability. - Crop-dominated agroecosystems have higher human carrying capacities and are more efficient, concerning nitrogen losses per unit of nitrogen in the food produced, than livestock-dominated agroecosystems. - Neither the Tanzanian nor the Scanian agroecosystems can be judged as being sustainable. - There were high losses of nitrogen from livestock manure/excreta, especially in the Scanian agroecosystems. - Biological nitrogen fixation on cultivated land was the most important input in the Scanian agroecosystems and has a large potential for improving the negative nitrogen budgets of cultivated land in the Tanzanian systems.
Original languageEnglish
QualificationDoctor
Awarding Institution
  • Department of Biology
Supervisors/Advisors
  • [unknown], [unknown], Supervisor, External person
Award date1999 Sep 24
Publisher
ISBN (Print)91-7105-113-9
Publication statusPublished - 1999

Bibliographical note

Defence details

Date: 1999-09-24
Time: 10:15
Place: Ecology Building, Lund University

External reviewer(s)

Name: Ebbersten, Sten
Title: [unknown]
Affiliation: [unknown]

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The information about affiliations in this record was updated in December 2015.
The record was previously connected to the following departments: Plant Ecology and Systematics (Closed 2011) (011004000)

Subject classification (UKÄ)

  • Ecology

Keywords

  • nutrient
  • nutrient model
  • nutrient cycling
  • nitrogen fixation
  • nitrogen budget
  • mixed system
  • miombo
  • manure
  • livestock
  • land use
  • historical system
  • food production
  • efficiency
  • crops
  • agroecosystem
  • carrying capacity
  • phosphorus
  • Scania
  • sustainability
  • Plant ecology
  • Växtekologi

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