Impacts of different prescribed fire frequencies on selected soil chemical properties in a semi-arid savannah thornveld

Abstract

Effects of fire frequency on soil chemical properties in semi-arid savannahs are still unclear. A study was conducted on a long-term fire research trial in the semi-arid part of Eastern Cape Province, South Africa. The study aimed at determining the impact of outbreak on the soil properties by comparing the effect of different prescribed fire frequencies on pH, C, N, P, Ca, Mg, Cu, Zn, Mn, Na levels and C:N ratios. The treatments were no burn (control), sexennial, quadrennial, triennial, biennial and annual burns randomly laid in uniform blocks. A line intercept sampling technique was used in soil sampling from 0 to 75 mm depth for analysis. Fire burning frequencies had significantly varied effects on soil chemical properties (P < 0.05). There was an increase of C, Mg and Ca in the triennial than other frequency treatments. Significant positive correlations were observed between N and P, Ca and Mg and pH and Ca and Mg content and burning frequencies. C and other elements content were reduced in most burning frequencies except triennial. The triennial burning frequency may be an ideal option for veld management. Further studies under different climatic conditions, soil and vegetation types and fractionation analysis of chemical elements are necessary to determine whether different frequencies result in short-or long-term fire-induced changes.

Keywords:

• Burning regime
• fire outbreak
• fractionation
• heat
• veld fire
• veld management

PUBLIC INTEREST STATEMENT

Unlike the wildfires, prescribed fires are useful tools for veld management. However, fire can be highly destructive to the environment if uncontrolled. The effects of prescribed fires on soil properties and functioning are usually generalized leading to soil degradation. In order to quantify the effects of fire on the soil chemical properties, six different fire burning frequency regimes (no burn, annual, biennial, triennial, quadrennial and sexennial burns) were studied at the University of Fort Hare (UFH) research farm. Effects of the fire burning frequencies on the soil properties were dynamic. Some burning frequencies enhanced the soil properties while others degraded the soil. The triennial burning was the best practice in rangeland management because it had positive effects on the soil chemical properties. It can be recommended to burn the veldt after every three years especially in areas with similar climatic conditions with the UFH research farm.

Competing Interests

The authors declares no competing interests.

Disclosure statement

There was no potential conflict of interest reported by the authors.

Additional information

Funding

The authors received no direct funding for this research.

Notes on contributors

C. Parwada

Dr C. Parwada is a senior lecturer at the Women’s University in Africa. He is soil scientist with sound background in agronomy. He has published many articles related to crop production and soil fertility and conservation.

M.I. Magomani

Mr. M.I. Magomani graduated with an MSc Soil Science from the University of Fort Hare and is currently a senior lecturer at the Fort cox college of Agriculture and Forestry, South Africa. He is a seasoned lecturer and researcher in soil science.

J.J. van Tol

Professor J.J. van Tol is a renowned researcher in soil science and hydropedology at the University of the Free State formerly with the University of Fort Hare, South Africa. In addition, he is a well renowned researcher in soil science and agronomy.