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Passive vs active restoration to improve soil health of old potato production circles in the Leipoldtville Sand Fynbos, South Africa
Author
Swanepoel, A
Saayman, N
Swart, R
Rheeder, C
Publisher
XII International Rangeland Congress
Publication Year
2025
Body

Potato production is the main land use in the endangered Leipoldtville Sand Fynbos vegetation type on the west coast of South Africa. Many fields have been abandoned and the ir restoration is important to conserve this vegetation type. These abandoned fields are subject to wind erosion and have high soil phosphorous levels due to fertilisation. We addressed the question " Does active restoration enhance soil health faster than natural processes?" We selected three sites, all in sandy soils with high soil phosphorous levels (35 – 63 mg/kg) compared to the surrounding natural vegetation (7 –11 mg/kg). Cultivation had ended 5 –7 years previously and sites were in different states of recovery. Seven treatments were applied, including planting of indigenous species, an initial rye mix consisting of cereal rye, lupins and serradella, and brush packing using branches from invasive trees packed in a single layer at a density of 50 –80% soil cover, in various combinations, as well as a control. Soil samples were collected to determine changes in phosphorous levels using citric acid analysis, organic carbon using the Walkley-Black method, and microbial diversity using Biolog EcoPlates. Due to drought from 2017 –2020 the initial rye mix established poorly and had little impact on the soil-P levels. Phosphorous levels decreased over time at two of the sites but increased significantly at Site 3, adjacent to active croplands. Organic carbon increased over time at Site 2 and Site 3. At Site 1, with the least natural plant cover, organic carbon only increased in the treatments that included brush packing. At all sites there was a significant increase in soil microbial diversity, but at Site 1 it was better in treatments with brush packing. There was an improvement in overall soil health over time. Abandoned fields with the least natural cover benefited most from restoration actions.

Language
English
Resource Type
Text
Document Type
Conference Proceedings
Additional Information
This paper is part of the larger XII International Rangelands Congress Proceedings. Page Numbers: 1212-1216. Theme: Theme 4 / Poster presentations – Theme 4
ISSN
978-0-646-72121-7
Conference Name
International Rangeland Congress
Collection
International Rangelands Congress
Keywords
brush packing
soil phosphorous
soil organic carbon
indigenous plants