Page 6 - MRC Newsletter Ed-1 (2021)

Spent Mushrooms Substrate

(SMS) and its benefits to

the environment

Dr Horn is a plant breeder and her gardening companies use spent
role on crop improvement using substrate as the choice ingredient
nuclear science and technology for potting mixtures that are sold in
(Induced mutation by Gamma supermarkets and garden centres.
irradiation) led to the development Dr Horn recommended the use of
of Namibia’s first ever mutant SMS as it reduces environmental Dr Lydia Horn
germplasms of cowpea, pearl waste from mushrooms production. Researcher, ZERI
millet and sorghum. In her article, She further revealed that scholars
she narrated that spent mushrooms have shown how one of the major the harvesting of mushrooms.
substrate (SMS) is high in organic environmental problems in the She further posited that ZERI saw
matter, making it desirable for mushroom producing countries an opportunity to utilise spent
use as a soil amendment or soil remains the treatment and disposal mushroom substrate as a medium
conditioner. MRC researcher Dr of the spent mushroom substrates for vegetable growth and as pot
Horn takes us through the process (Medina et al., 2009) and she filling materials.
of preparing SMS and its value. She asserted that in some countries,
stated that, “substrate prepared about 5 kg of SMS is produced for
specifically for growing mushrooms each kilogramme of mushrooms Quoting from reputable scholars, Dr
is a blend of natural products and (Paredes et al., 2009) and that Horn enlightened that SMS normally
ZERI, for example, the common Spain alone produces SMS that contains 1.9:0.4:2.4%, N-P-K before
materials used are maize straws and is approximately 800,000 tonnes weathering and 1.9:0.6:1.0, N-P-K
cobs, mahangu/pearl millet straws, per annum which as research after weathering for 8-16 months
wheat straws and wood chips”. shows, could be detrimental to the (Ahlawat & Sagar, 2007) and that
She was however quick to point out country’s environmental health nitrogen and phosphorus do not
that, “common ingredients used (Ahlawat & Sagar, 2007). leach out during weathering,
in other countries include horse thereby making the SMS an ideal
manure, hay, corn cobs, cotton Mushroom production and medium for plant growth.
seed hulls, poultry manure, brewer's promotion in Namibia is being
grain, cottonseed meal, cocoa carried out at the Zero Emission SMS has also been used in the
bean hulls and gypsum.” In some Research Initiative (ZERI) Division production of foliage crops as a
countries, spent substrate is spread under the Multi-Disciplinary potting mix (Rinker, 2017; Wuest
in the field for one season to allow Research Centre (MRC) at the et al., 1995). Dr Horn narrated
maturity and Dr Horn revealed that University of Namibia. Dr Horn how an experiment to utilise SMS
researchers at ZERI are learning revealed that “to date, ZERI started in 2019 at the ZERI division.
and applying these good practices has trained a large number of “Various vegetable crops such as
from other countries. mushroom growers in Namibia and
in the SADC region. The project spinach, lettuce, sweet potatoes,
Dr Horn further stated the widely also has success stories such as and gourd are being tested under
held scholarly view that aged domestication of indigenous the greenhouse environment and
spent substrate is good for soil mushroom varieties which are preliminary results show that the
improvement and crop growth processed into dietary supplements spent substrate can be used as a
(Grimm & Wösten, 2018). She and capsules.” Dr Horn further medium for plant growth especially
further stated that Sendi (2014) indicated that mushrooms at ZERI in the urban areas where potting
and Rinker (2017) have provided are grown on crop residues which soils are expensive”, concluded Dr
information on how landscape and become spent substrate, after Horn.

06 RESEARCH MATTERS VOL 8. 2021 MULTIDISCIPLINARY RESEARCH CENTRE