Vegetative Mulches in Tonga

Name of case study

Vegetative Mulches in Tonga

Location

Tonga

Year

2017

Scale

urban/landscape scale

Area / size

Not available

NbS employed

Mulch

Type of NbS

Ecosystem protection

Initiator

Not available

Funder

University of New England and the Tongan Ministry of Agriculture and Forestry (MAF)

Budget

Not available

Design group

Not available

A mulched taro crop. Photo by Su Ba from Homesteading in Hawai’i http://kaufarmer.blogspot.com/2015/02/taro-standing-mulch-update.html
Climate change benefits
  • Loss of food production
  • Reduced soil quality
Societal / socio-cultural benefits
  • Climate change adaptation
  • Food security and quality
Ecological benefits
  • Decomposition
  • Disturbance prevention 
  • Food production (for humans)
  • Nutrient cycling
  • Soil building
  • Provision of raw materials

Summary of case study

This study conducted two experiments focusing on the growth and yield of taro and paper mulberry, both important Indigenous crops in Tonga (Manu et al., 2018). Mulch was utilised as to enhance agricultural productivity and sustainability in the experiment. The study utilised readily available mulch materials like guinea grass to present a practical and feasible option in the context of Tonga.

The resulting 81% increase in Taro corm (root) yield compared to conventional farming methods was attributed to increased soil moisture and improved soil structure, both crucial to plant growth especially in dry conditions (Manu et al., 2018).

In the case of Paper Mulberry, use of mulch increased the bark yield by 30% compared to the control (Manu et al., 2018). This increase is especially significant given the crops is used in the production of tapa cloth, an Indigenous material with significance both culturally and economically.

The authors utilised mulch to improve soil moisture retention, soil quality and reduce erosion in agricultural settings. The application of mulch reduced soil loss by up to 50% on sloping land cultivated with Taro (Manu et al., 2018). This reduction is an important finding for reducing soil degradation, which is common in intensively used agricultural land (Feary, 2011).

Mulching reduced the weeding required across the study, resulting in reduced labour costs. This is beneficial because labour costs often constitute a significant portion of expenses for small-scale agriculture (Georgeou et al., 2022). 

The use of mulch resulted in higher net profits compared to non-mulched areas, T$2660/ha for taro and T$12,108/ha for paper mulberry (Manu et al., 2018). This highlights the economic viability of mulch as a method to incorporate into agriculture for local people producing food and other plant resources.

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References
  • Feary, A. (2011). Restoring the Soils of Nauru: Plants as Tools for Ecological Recovery [Open Access Te Herenga Waka-Victoria University of Wellington]. https://doi.org/10.26686/wgtn.16992997
  • Georgeou, N., Hawksley, C., Wali, N., Lountain, S., Rowe, E., West, C., & Barratt, L. (2022). Food security and small holder farming in Pacific Island countries and territories: A scoping review. PLOS Sustainability and Transformation, 1(4), e0000009. https://doi.org/10.1371/journal.pstr.0000009
  • Manu, V., Whitbread, A., & Blair, G. (2018). Effects of vegetative mulches on growth of indigenous crops in the Kingdom of Tonga. Soil Use and Management, 34(1), 147–153. https://doi.org/10.1111/sum.12398

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