Trond Haraldsen
Research Professor
(+47) 928 04 196
trond.haraldsen@nibio.no
Place
Ås O43
Visiting address
Oluf Thesens vei 43, 1433 Ås
Abstract
This study evaluates the effectiveness of various peat-free and peat-reduced growing media on the growth and yield of tomatoes and carrots, with the aim to develop sustainable alternatives to traditional peat-based substrates in horticulture. Thirty different growing media mixtures were tested, incorporating materials such as wood fiber, compost, biochar, bio-ash, and struvite, with the goal of identifying viable alternatives to peat. The experiments were conducted in greenhouse conditions, and the performance of these mixtures was assessed based on yield and overall vitality of tomato and carrot plants. The results revealed that fully peat-free mixtures generally underperformed compared to peat-based references. However, some peat-reduced mixtures with 30% peat in combination with wood fiber, compost, struvite or bio-ash demonstrated promising results. Bio-ash and struvite were evaluated as phosphorus sources, with findings suggesting that both materials can enhance substrate fertility when combined with appropriate nitrogen fertilizers. The effect of biochar was not very pronounced in general. Moreover, the addition of biochar was associated with a disappearance of plant-available nitrogen from the growing media, which likely contributed to its limited effectiveness in improving crop performance. The study underscores the continual challenge of completely phasing out peat in growing media for horticulture but highlights the potential of reducing it greatly and integrating more sustainable materials such as wood fiber and recycled materials such as compost, bio-ash and struvite. The results suggest that with further refinement, specific combinations of these materials could be developed into optimized substrate mixtures for sustainable horticultural practices without compromising productivity.
Abstract
Abstract The primary benefits of turfgrass sod include rapid greenery and soil coverage, but its production causes concerns about soil losses at production sites. Soil adheres to the grass root system during harvesting and is removed from the sod farm, which in the long run might lead to soil degradation on the sod farm. In this study, we investigated sod thickness and the removal of organic and mineral matter when harvesting 24 fields representing 12 Norwegian sod farms in 2022 and 2023. On each field, 10 sod strips were randomly chosen, and five sod plugs were collected from each strip. Sod thickness was measured using a sliding gauge. Sod mineral matter (SMM: soil and thatch mineral matter) and sod organic matter (SOM: soil and thatch organic matter) contents were quantified by loss on ignition at 550°C. Management and field properties were also documented. Results showed an average amount of mineral matter in the sod strips of 36 Mg ha −1 for all fields but with significant variation among fields ( p < 0.001). The average SOM content was 10 Mg ha −1 . Mean sod thickness was 15.4 mm and had a strong correlation with SOM ( r = 0.8) but only a moderate correlation with SMM ( r = 0.6). Soil water content and surface hardness at harvest affected sod thickness and SMM only slightly. Sod harvesters with twin heads harvested significantly thicker sod strips and removed more mineral matter than harvesters with single cutting heads. Soil texture did not have a significant impact on sod thickness or mineral matter removal.
Abstract
In this study the effects of growing annual and perennial plant species in five growing media blends; one peat-based, two peat-reduced and two peat-free. Three main components were used in the blends: sphagnum peat (P-Soil (PS), Wood fiber substrate (WFS), Peat reduced blend (PRB)), coarse wood fiber (Fibergrow®) of Norway spruce (Picea abiens) (WFS, PRB, Circle soil (Circle), PFB) and garden/park waste-based compost (Circle, PRB, PFB). The peat-based reference (P-Soil) contained 10 vol.% composted bark in addition to sphagnum peat. pH in the blends ranged from 5.1 to 6.4. Both annual and perennial plants were tested in the five blends, and large differences in growth and vitality of plants grown in the different blends were observed. The performance of most plant species grown in Circle, PRB and PFB was characterized as satisfactory, while P-Soil gave the best results and was used as reference as it is commonly used in the plant nursery. Plants grown in WFS showed generally weak growth and the plant growth was characterized as unsatisfactory. However, WFS and PRB performed satisfactory to seedlings of Rhododentron uniflorum, while Circle and PFB failed to give satisfactory growth of rhododendron seedlings. Although all blends were basic fertilized with different types of compound mineral fertilizers, chemical analyses showed significantly lower concentrations of CAT-soluble plant nutrients in WFS compared to the other blends. N-immobilization during storage in plastic bags may have occurred for WFS, which has very high C/N-ratio. In the blends with compost and Fibergrow® the expected levels of mineral N were found, and no N-immobilization occurred. In the blends with compost almost all mineral N was present as nitrate-N, while ammonium-N dominated in P-Soil. There were no large differences in root development between the five blends, and the root growth in WFS was good despite significantly smaller plants than in the other blends.