A 2-year field trial determined the influence of applying spent mushroom
substrate (SMS) on soil physical properties and the growth of 4 consecutive
vegetable crops (sweetcorn, cabbage, potato, cabbage). Treatments comprised 0,
20, 40, and 80 t/ha of moist SMS, both with and without inorganic
fertiliser, applied to each crop, giving a range of SMS rates up to 320
t/ha.
SMS improved the environment for plant root growth by decreasing soil bulk
density (by 0· 05-0·25 g/cm 3 at 100 mm depth), increasing
aggregate stability (by 13-16%), reducing clod and surface crust
formation (by 16-31 and 18-94%, respectively), increasing the
infiltration rate (by 130-207 mm/h), increasing the water content of the
soil (by 0-7% w/w), and reducing diurnal temperature changes. Some
of these changes were not evident until repeated applications of 80 t/ha
SMS had been made.
Soil physical properties were related to crop yield, and soil physical
properties’ principal components were related to crop principal
components using regression analysis
(r2 of 0·20-0·60 and
0·16-0·54, respectively). The soil physical properties that had
the most influence on plant growth were specific to each crop and included
bulk density, water content, surface crust cover, infiltration rate, and
aggregate size distribution. Soil physical properties had a large influence on
the potato yield irrespective of fertiliser use and on both cabbage crop
yields when fertiliser was not used, but not on the sweetcorn yield (the first
crop to be grown). The effect of changing soil physical properties on plant
growth was most apparent when fertiliser was not used. This was because the
improved physical properties increased plant yield (at least in part) because
of increased plant nutrient uptake.
Demonstration gardens with EDTA-washed soil. Part III: Plant growth, soil physical properties and production of safe vegetables
