Search Results
Concerns over the environmental impact and economics of harvesting sphagnum and reed-sedge peat have increased the desire to identify acceptable peat substitutes for use in container substrates. This preliminary study evaluated the use of composted dairy manure solids as a substitute for sphagnum or reed-sedge peat in container substrates for production of woody ornamental shrubs and assessed potential leaching of nutrients. Walter's viburnum (Viburnum obovatum), sandankwa viburnum (Viburnum suspensum), and japanese privet (Ligustrum japonicum) were grown in 3-gal plastic containers with seven substrates containing (by vol.) 60% pine bark, 10% sand, and 30% sphagnum peat (S), reed-sedge peat (R), and/or composted dairy manure solids (C). Substrate composition had no effect on plant quality ratings for any species, growth index (GI) of walter's viburnum, or shoot and root dry weight of walter's viburnum and japanese privet. However, the GI of japanese privet and sandankwa viburnum was the lowest when grown in substrates containing a high percentage of reed-sedge peat (0S:3R:0C). Substrate effects on average nitrate + nitrite nitrogen leachate losses were minimal over the 88-day leachate collection period. However, the substrate containing the highest proportions of composted dairy manure solids (0S:0R:3C) generally had the highest average ammonium nitrogen and dissolved reactive phosphorus losses compared with other substrates. All substrates tested as part of this study appeared to be commercially acceptable for production of container-grown woody ornamental shrub species based on growth and quality. However, average nutrient losses from containers differed depending on the peat or peat substitute used to formulate the substrates.
Recent concerns over the environmental impact of peat harvesting have led to restrictions on the production of peat in Florida and other areas. The objectives of this study were to evaluate the use of composted dairy manure solids as a substitute for sphagnum or reed-sedge peat in container substrates on the growth of Solenostemon scutellarioides L. Codd ‘Wizard Velvet’, Tagetes patula L. ‘Safari Queen’, and Begonia ×hybrida ‘Dragon Wing Red’ and to examine the nutrient content in leachate from pots. Plants were grown for 5 weeks in a greenhouse in 15-cm plastic pots with seven substrates containing various proportions of sphagnum peat (S) or reed-sedge peat (R) and composted dairy manure solids (C), each with 20% vermiculite and 20% perlite. Substrate composition had no effect on plant quality ratings, number of flowers, or root dry mass for any of the plant species evaluated. Substrate composition did not affect the growth index (GI) or shoot dry mass of S. scutellarioides ‘Wizard Velvet’ or the GI of T. patula ‘Safari Queen’. However, growth of B. ×hybrida ‘Dragon Wing Red’ (GI and shoot dry mass) and T. patula ‘Safari Queen’ (shoot dry mass only) was highest in the 3S:0R:0C substrate. The substrates containing sphagnum peat and/or composted dairy manure solids (3S:0R:0C, 2S:0R:1C and 1S:0R:2C) had the highest NH4-N losses through the first 7 d of production. The 0S:3R:0C substrate had the highest initial leachate NO3+NO2-N losses and this trend persisted throughout most of the production cycle. Significantly more dissolved reactive phosphorus was leached from substrate mixes containing composted dairy manure solids than mixes containing only sphagnum or reed-sedge peat materials through 19 d after planting. All substrates tested as part of this study appeared to be commercially acceptable for production of container-grown bedding plant species based on plant growth and quality. However, nutrient losses from the containers differed depending on the peat or peat substitute used to formulate the substrates.
Previous research on #3 nursery container-grown shrubs suggests that some common shrub species could be established in the Florida landscape under natural rainfall when irrigated with 3 L of water every 4 days in U.S. Department of Agriculture hardiness zones 8b and 9a or every 2 days in zone 10b until first roots reached the canopy edge (≈20 weeks after planting). The current study evaluated the effects of these irrigation frequency recommendations on plant vigor, canopy growth, root growth, and aesthetic quality of 21 common landscape shrub species (10 Florida native and 11 non-native) planted in Florida in zones 8b, 9a, or 10b. Data suggests that it may be appropriate to adopt the 20-week low-volume irrigation recommendations for the establishment of a wide variety of container-grown Florida native and non-native shrubs. However, Florida native and non-native shrubs should be monitored for symptoms of drought stress for 2 years after planting.