In Western and Northern parts of Norway a significant amount of grass swards exceed ten years. Low renovation activity may be due to swards are often located in marginal areas, low or no yield in the renovation year, and the cost of a new sward establishment. This project focuses on assessing permanent grassland renovation strategies as regards their potential to sustain high productivity with low costs.
The experimental design of existing long-term grassland experiments at the NIBIO locations Særheim and Fureneset was modified. Temporary leys which were reseeded every 3rd and 6th year will be ploughed and reseeded every 6th and 12th year and either sod-seeded or no every 3rd year. Also, the 25 years non-tilled grassland will be renewed with or without ploughing. In 2016 these treatments were fertilized, ploughed and reseeded. In contrast, the 50 years non-tilled grassland remained undisturbed. Mean yield level in long-term grasslands are high, 800 kg DM daa-1 and year. Renewed 25 years grassland with ploughing produced some more DM than old grassland renewed by sod-seeding at Særheim with opposite result at Fureneset.
In old grasslands sod-seeding after the first harvest was carried out with commercially available sowing machines at Tjøtta, Fureneset, Løken and at Sunndal (Møre and Romsdal) and Lofoten (Nordland). Moderate and low seed germination was seen in directly reseeded old swards. Sod-seeding in early spring was also tested and the results were promising.
Economic analyses showed that long-term ley was more profitable than the examined renewal strategies. Use of glyphosate spraying of the sward before direct reseeding was more profitable than conventional renewal at Fureneset, while direct seeding of ryegrass (without use of glyphosate) had the lowest economic return at Særheim. Results were sensitive to the assumed price of forage.
Decomposition of litterbags in the long-term grassland fields showed that from 75 to 90% of plant material was decomposed during the first three months of burial period. The results indicate a higher degree of microbial activity in long-term sward than in short-term sward.
A pot experiment assessing how liming affects nitrogen (N) uptake in timothy and smooth grass was tested. In unfertilised pots liming increased uptake of soil N. There was initial response to N added, but no difference to the amount of N.
New methods for improving the synergy of seed mixtures based on principles developed by Agroscope (CH) and others were discussed in a seminar at Gardemoen. Field trials with seed mixtures suitable for long-term grasslands were established at Tjøtta, Fureneset and Løken. In general, the yield differences between seed mixtures were higher between sites than within sites. At Tjøtta and Fureneset seed mixtures of leafy species performed better than timothy-based mixtures due to the longer growing season and the low regrowth capacity of timothy. The opposite picture was seen at Løken. The recommendations from the seed companies should be more directed to local conditions.
Inoculation efficiency of different bacterial strains, soil types and cultivars were studied in lucerne. Marketed inoculation strains were compared with no inoculation. Supplemental field trials were established at Tjøtta on sandy soil and at Løken on silty soil. The pot experiment revealed significantly better plant growth, flower number and nodule development as well as plant regrowth after winter survival using dry inoculation. Peat soil appeared as the best growth medium. Dry inoculation should be recommended for practical use and replacing peat slurry inoculation.
In spring 2016, prior to the renewal of the old grassland experiments and in spring 2019, soil samples were taken to assess weed seed bank, indicating a larger seedbank in soil at depth of 0-5 cm than at 5-18 cm soil depth. In the deeper soil layer less weed seeds were detected in long-term grasslands compared to frequently renewed grasslands. Renewal of old grassland by ploughing resulted in higher weed seed-bank only at Fureneset.
Couch grass is generally considered as a weed, but in long-term grasslands it can be used as a forage due to acceptable nutritive value and satisfactory yield capacity. In grass fields dominated by couch grass in mountainous region, North-West and North-Norway indicated that such grasslands might produce high DM yields with good forage quality, particularly at the first harvest. In the second harvest couch grass might have negative effect on the energy and fibre content.
Experiments in Sweden showed that rhizome fragmentation with vertical discs could be a good method to control couch grass in old swards.
The project is financed by the Norwegian Research Funding for Agriculture and the Food Industry and several Norwegian industry and governmental partners.
På kort sikt 1. Forskere med ulik bakgrunn økte kunnskapen om langvarig eng, fornyingsmetoder uten pløying og fornyingskostnader. 2. Tilgang på kunnskap om arts- og sortsblandinger av gras og belgvekster som er tilpasset fornying av og direktesåing i eldre eng. 3. Nyttig kunnskap om nye lusernesorter og smittekilder til lusernefrø. 4. Mer kunnskap om ugrasfrøbank i langvarig eng. 5. Dokumentasjon om kveke som fôrplante. 6.Vertikalskjærer i eng - lovende metode for mekanisk ugraskontroll. På lang sikt. 1. Større interesse for artsrike frøblandinger og bruk av luserne i norsk grovfôrproduksjon. 2. Vertikalskjærer er tilgjengelig for næringen.
Forage production is one of the main pillars of Norwegian food production in which an important issue is to increase and maintain grassland yields effectively. The main research tasks in the four-year project LONGTERMGRASS are to find smart renewal or renovation methods that improve maintenance of forage quantity and herbage quality particularly in long-term grasslands and indirectly lead to better carbon storage. To approach this, we will make use of two existing long-term grassland experiments and establish new experiments in different regions of Norway to:
1) test reseeding/renovation methods on herbage yield and quality,
2) study the influence of soil liming and fertilisation on yield, soil physical properties, decomposition rate and plant nitrogen uptake,
3) develop grass and grass-legume seed mixtures appropriate for long-term grassland for diverse growing conditions and for sod-seeding in old swards,
4) find environmentally sound methods of perennial weed control in grasslands and assess advantages and disadvantages of couch grass as forage,
5) calculate the economic value of maintaining long-term sward.
We will use an integrated approach by combining field experiments with experiments in a phytotron/greenhouse, advanced chemical analyses and economical models. The project is supported by commercial companies connected to fertilization and seed trade, farmers organisations, regional agricultural and municipal authorities, and Graminor Ltd. and the agricultural extension service (NLR) participate. This will ease the flow of information from research to farmers. High-rating institutes in England and in Switzerland will also be involved. The project will contribute to the following research priorities of the FFL/JA announcement (Matfondavtalen): cost-effective forage yields per grassland area and good forage quality and good agronomy. The project will thereby indirect contribute to reach the national goal of more food production.