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Soil, land care and environmental research
RESEARCH ARTICLE

Role of soil quality in declining rooibos (Aspalathus linearis) tea yields in the Clanwilliam area, South Africa

Jacobus F. N. Smith A , Alfred Botha B and Ailsa G. Hardie A C
+ Author Affiliations
- Author Affiliations

A Department of Soil Science, University of Stellenbosch, P/Bag X1, Matieland, 7602, South Africa.

B Department of Microbiology, University of Stellenbosch, P/Bag X1, Matieland, 7602, South Africa.

C Corresponding author. Email: aghardie@sun.ac.za

Soil Research - https://doi.org/10.1071/SR17029
Submitted: 19 January 2017  Accepted: 3 October 2017   Published online: 29 November 2017

Abstract

Global demand for rooibos tea is increasing whereas yields are decreasing in the primary production area of Clanwilliam, South Africa. Commercial rooibos producers report that tea yields decline over time following the initial clearing of the natural fynbos veld. Therefore, the aim of this study was to investigate soil and plant quality in cultivated rooibos plantations of various ages (1–60 years) and adjacent, wild rooibos stands in pristine fynbos in the Clanwilliam area. Soil chemical and physical properties, plant total biomass, tea yields, foliar elemental contents, extent of root nitrogen (N) nodulation and mycorrhizal colonisation were assessed. The most prominent soil quality changes at the oldest cultivated sites compared with pristine fynbos soils were an increase in soil phosphorus (P) from 1.3–1.7 mg kg–1 to 4.0–17.0 mg kg–1, a general decline in total carbon from 0.14–0.29% to 0.09–0.10% and decline in total exchangeable basic cations from 0.64–0.78 cmolc kg–1 to 0.34–0.51 cmolc kg–1, and a concomitant increase in exchangeable aluminium (Al) from 0.10–0.30 cmolc kg–1 to 1.03–1.83 cmolc kg–1. Foliar N : P ratios notably declined at the cultivated sites (12 : 0 – 20 : 1) compared with pristine fynbos sites (27 : 1 – 33 : 1), indicating foliar P accumulation and lack of N. Soil P was strongly negatively correlated with rooibos root mycorrhizal colonisation. The decline in soil organic matter and basic cations, especially potassium (K), was most strongly correlated with the decline in rooibos shoot biomass yields at cultivated sites. These findings highlight the significant role of soil quality in declining yields of rooibos tea in the Clanwilliam area. Management practices should be implemented that increase soil organic matter and essential basic cations such as K, and soil P and exchangeable Al levels should be monitored.

Additional keywords: soil degradation, soil fertility.


References

Asimi S, Gianinazzi-Pearson V, Gianinazzi S (1980) Influence of increasing soil phosphorus levels on interactions between vesicular–arbuscular mycorrhizae and Rhizobium in soybeans. Canadian Journal of Botany 58, 2200–2205.
Influence of increasing soil phosphorus levels on interactions between vesicular–arbuscular mycorrhizae and Rhizobium in soybeans.CrossRef | 1:CAS:528:DyaL3MXhsVCgsQ%3D%3D&md5=50f676d4aee4169f9266139358b11b07CAS |

Bingham FT (1982) Boron. In ‘Methods of soil analysis: Part 2’. (Ed. AL Page) pp. 301–312. (America Society of Agronomy: Madison, WI)

Blake G, Hartge K (1986) Bulk density. In ‘Methods of soil analysis: Part 1’. (Ed. A Klute) pp. 365–375. (America Society of Agronomy: Madison, WI)

Brady NC, Weil RR (2007). ‘Nature and properties of soils’. (Pearson International: USA)

Brundrett M, Melville L, Peterson L (1994a) Clearing and staining mycorrhizal roots. In ‘Practical methods in mycorrhiza research’. pp. 42–46. (Mycologue Publications: Waterloo, Canada)

Brundrett M, Melville L, Peterson L (1994b) Estimation of root length and colonization by mycorrhizal fungi. In ‘Practical methods in mycorrhiza research’. pp. 51–61. (Mycologue Publications: Waterloo, Canada)

Chimphango SBM, Hattas D, Oettle N (2015) Effect of organic cultivation of rooibos tea plants (Aspalathus linearis) on soil nutrient status in Nieuwoudtville, South Africa. South African Journal of Plant and Soil 33, 13–21.
Effect of organic cultivation of rooibos tea plants (Aspalathus linearis) on soil nutrient status in Nieuwoudtville, South Africa.CrossRef |

Dahlgren R (1968) Revision of genus Aspalathus. Part II The species with the ericoid and pinoid leaflets. Subgenus Nortiera with remarks on rooibos tea cultivation. Botaniska Notiser 121, 165–208.

du Preez CC, Van Huyssteen CW, Mnkeni PNS (2011) Land use and soil organic matter in South Africa: 1. A review on spatial variability and the influence of rangeland stock production. South African Journal of Science 107, 1–8.

Gee GW, Bauder JW (1986) Particle-size analysis. In ‘Methods of soil analysis: Part 1’. (Ed. A Klute) pp. 383–409. (America Society of Agronomy: Madison, WI)

Grant C, Bittman S, Montreal M, Plenchette C, Morel C (2005) Soil and fertilizer phosphorus: Effects on plant P supply and mycorrhizal development. Canadian Journal of Plant Science 85, 3–14.
Soil and fertilizer phosphorus: Effects on plant P supply and mycorrhizal development.CrossRef |

Habte M, Manjunath A (1987) Soil solution phosphorus status and mycorrhizal dependency in Leucaena leucocephala. Applied and Environmental Microbiology 53, 797–801.

Hawkins H, Hettasch H, Mesjasz-Przybylowicz J, Mesjasz-Przybylowicz W, Cramer M (2008) Phosphorus toxicity in the Proteaceae: A problem in post-agricultural lands. Scientia Horticulturae 117, 357–365.
Phosphorus toxicity in the Proteaceae: A problem in post-agricultural lands.CrossRef | 1:CAS:528:DC%2BD1cXptVWitr4%3D&md5=cc5ad14db4362daca3352c64fae86e90CAS |

Hawkins HJ, Malgas R, Bienabe E (2011) Ecotypes of wild rooibos (Aspalathus linearis (Burm. F) Dahlg., Fabaceae) are ecologically distinct. South African Journal of Botany 77, 360–370.
Ecotypes of wild rooibos (Aspalathus linearis (Burm. F) Dahlg., Fabaceae) are ecologically distinct.CrossRef |

Hillel D (1998) ‘Environmental soil physics’. (Academic Press: San Diego USA)

Joubert E, de Beer D (2011) Rooibos (Aspalathus linearis) beyond the farm gate: from herbal tea to potential phytopharmaeutical. South African Journal of Botany 77, 869–886.
Rooibos (Aspalathus linearis) beyond the farm gate: from herbal tea to potential phytopharmaeutical.CrossRef |

Joubert M, Kotze W, du Preez D (1987) Voedingsbehoefte van Rooibostee. Tuinbouwetenskap 5, 11–14.

Kalra YP (1998) ‘Handbook of standard methods of plant analysis’. (CRC Press: Boca Raton USA)

Kanu SA, Okonkwo JO, Dakora FD (2013) Aspalathus linearis (Rooibos tea) as potential phytoremediation agent: a review on the tolerance mechanisms for aluminium uptake. Environmental Reviews 21, 85–92.
Aspalathus linearis (Rooibos tea) as potential phytoremediation agent: a review on the tolerance mechanisms for aluminium uptake.CrossRef | 1:CAS:528:DC%2BC3sXmt1SltrY%3D&md5=a56ec3af3054a01ce03529a6a75e78ebCAS |

Kuo S (1996) Phosphorus. In ‘Methods of soil analysis: Part 3’. (Ed. JM Bridgham) pp. 869–919. (America Society of Agronomy: Madison, WI)

Lambers H, Shane MW, Cramer MD, Pearse SJ, Veneklass EJ (2006) Root structure and functioning for efficient acquisition of phosphorus: Matching morphological and physiological traits. Annals of Botany 98, 693–713.
Root structure and functioning for efficient acquisition of phosphorus: Matching morphological and physiological traits.CrossRef |

Lehto T (1992) Mycorrhizas and drought resistance of Picea sitchensis. New Phytologist 122, 661–668.
Mycorrhizas and drought resistance of Picea sitchensis.CrossRef | 1:CAS:528:DyaK3sXhs1ygs78%3D&md5=60e5477504e61f115293db90da308de0CAS |

Lötter D, Valentine A, Van Garderen E, Tadross M (2014) Physiological responses of a fynbos legume, Aspalathus linearis to drought stress. South African Journal of Botany 94, 218–223.
Physiological responses of a fynbos legume, Aspalathus linearis to drought stress.CrossRef |

Maistry P, Cramer M, Chimphango SMB (2013) N and P colimitation of N2-fixing and N-supplied fynbos legumes from the Cape Floristic Region. Plant and Soil 373, 217–228.
N and P colimitation of N2-fixing and N-supplied fynbos legumes from the Cape Floristic Region.CrossRef | 1:CAS:528:DC%2BC3sXptVyktbg%3D&md5=aef15c10b7974f0a6f6f661ec48e7283CAS |

Maistry P, Musaya AM, Valentine AJ, Chimpango SMB (2015) Increasing nitrogen supply stimulates phosphorous acquisition mechanisms in the fynbos species Aspalathus linearis. Functional Plant Biology 42, 52–62.

Malgas R, Potts A, Oettle N, Koelle B, Todd S, Verboom G, Hooman M (2010) Distribution, quantitative morphological variation and preliminary molecular analysis of different growth forms of wild rooibos (Aspalathus linearis) in the northern Cerderberg and on the Bokkeveld Plateau. South African Journal of Botany 76, 72–81.
Distribution, quantitative morphological variation and preliminary molecular analysis of different growth forms of wild rooibos (Aspalathus linearis) in the northern Cerderberg and on the Bokkeveld Plateau.CrossRef |

Morton J (1983) Rooibos tea, Aspalathus linearis, a caffeineless, low-tannin beverage. Economic Botany 37, 164–173.
Rooibos tea, Aspalathus linearis, a caffeineless, low-tannin beverage.CrossRef |

Muofhe M (1997) N2 fixation and rhizosphere ecology of Aspalathus linearis. MSc thesis, University of Cape Town, South Africa.

Muofhe M, Dakora F (1999) Nitrogen nutrition in nodulated field plants of the shrub tea legume Aspalathus linearis assessed using 15N natural abundance. Plant and Soil 209, 181–186.
Nitrogen nutrition in nodulated field plants of the shrub tea legume Aspalathus linearis assessed using 15N natural abundance.CrossRef | 1:CAS:528:DyaK1MXlt1emsrw%3D&md5=8a115fd504f1e9580c4aea31093e0a3aCAS |

Muofhe M, Dakora F (2000) Modification of rhizosphere pH by the symbiotic legume Aspalathus linearis growing in a sandy acidic soil. Australian Journal of Plant Physiology 27, 1169–1173.

Olsen RV, Ellis R (1982) Iron. In ‘Methods of soil analysis: Part 2’. (Ed. AL Page) pp. 301–312. (America Society of Agronomy: Madison, WI)

Rowell D (1994) ‘Soil science: methods and applications.’ (Longman Scientific & Technical: Singapore)

Singh S, Tripathi DK, Singh S, Sharma S, Dubey NK, Chauhan DK, Vaculik M (2017) Toxicity of aluminium on various levels of plant cells and organism: A review. Environmental and Experimental Botany 137, 177–193.
Toxicity of aluminium on various levels of plant cells and organism: A review.CrossRef | 1:CAS:528:DC%2BC2sXjtlyqsLc%3D&md5=83796d77c0ddcc906d40c9342efa1a10CAS |

Soderberg K, Compton JS (2007) Dust as nutrient source for fynbos ecosystems, South Africa. Ecosystems 10, 550–561.
Dust as nutrient source for fynbos ecosystems, South Africa.CrossRef | 1:CAS:528:DC%2BD2sXhtVGmsbbK&md5=3d98242966475164ca70d9d8e42dc1d7CAS |

Strassen P (1987). Aspalathus linearis (Rooibostee): Die invloed van oespraktyke op sekere vegatatiewe en fisiologiese aspekte. DSc (Agric) thesis, University of Pretoria, South Africa

Thomas G (1982) Exchangeable cations. In ‘Methods of soil analysis: Part 2’. (Ed. AL Page) pp. 159–165. (America Society of Agronomy: Madison, WI)

USDA (2008) Soil quality indicators. USDA Natural Resources Conservation Service. Available at http://soils.usda.gov/sqi/assessment/files/bulk_density_sq_physical_indicator_sheet.pdf [Verified 26 September 2013]

Witkowski E, Mitchell D (1987) Variations in soil phosphorus in the fynbos biome, South Africa. Journal of Ecology 75, 1159–1171.
Variations in soil phosphorus in the fynbos biome, South Africa.CrossRef |

Zeng R (2006) Disease resistance in plants through mycorrhizal fungi induced allelochemicals. In ‘Allelochemicals: biological control of plant pathogens and diseases’. (Ed. K Inderjit) pp. 181–192. (Springer: Dordrecht, The Netherlands)

Zönnchen C, Schaaf W, Esperschütz J (2014) Effect of plant litter addition on element leaching in young sandy soils. Journal of Plant Nutrition and Soil Science 177, 585–595.
Effect of plant litter addition on element leaching in young sandy soils.CrossRef |



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