Sustainable production of greenhouse vegetables with organic fluid fertilizer and mycorrhiza

Summary

In the production of greenhouse vegetables, the decline of the wholesale price of tomato and cucumber has impaired the profitability of greenhouse enterprises. New species are sought for production to improve the profitability. In Finland only one quarter of the production of sweet pepper is domestic and the proportion of organic production is small. There is a remarkable market for domestic sweet pepper. However, the shortage of nutrients and water as well as the tolerance of stress are limiting the yield of sweet pepper.
In the organic greenhouse production commercial liquid fertilizers are used to insure the availability of nutrients during the formation of the yield. They are significantly more expensive than chemical fertilizers. The cost of supplemental liquid fertilizer could be reduced by developing a fertilizer based on animal urine. Urine is commonly available for free on farms. On the other hand, the sales of urine could when proven a functional liquid fertilizer, in principle make a significant source of income of the same order of the income from milk, when the price of urine would be derived from the price of the nutrients in the organic liquid fertilizers. Some entrepreneurs have already tried to use urine as a liquid fertilizer with great success.
In the greenhouse production the availability of nutrients, the uptake of water, the growth of plants, flowering and the tolerance of stress could be improved by mycorrhizal inoculation. Actually, almost all the plants cultivated in the greenhouse; vegetables, spices and berries (except cabbages e.g. rucola) benefit from mycorrhiza when the conditions for the function of these fungi are optimal. Because mycorrhiza supplies the plants especially with phosphorus there is not much use of mycorrhiza when the phosphorus content of the media is high. Mycorrhiza works best when the solubility of phosphorus in the media is low. On the contrary, a high nitrogen content does not impair the function of mycorrhiza.
From the Finnish soil, effective mycorrhiza strains have been isolated but these are not yet developed to commercial preparations. However, there have been positive experience of their advantages e.g. in spices, strawberry and flowers.
The aim of this part of study is to develop an animal originating affordable ecological liquid fertilizer for production of organic sweet pepper in greenhouses and clarify the feasibility of mycorrhiza inoculation in the production of spices and vegetables on different medias.
Materials and methods MTT Agricultural Engineering develops in co-operation with the University of Helsinki an animal urine originated liquid fertilizer suitable for organic greenhouse production. There is in the first phase of the research a test in a greenhouse lasting whole the production period (approx. 6 months) where 1) bovine urine as a supplemental fertilizer, 2) pig urine as a supplemental fertilizer, 3) a commercial organic liquid fertilizer by Biolan as a supplemental fertilizer, 4) media fertilized with chicken manure (natural fertilizer by Biolan) and 5) media fertilized with chicken manure (natural fertilizer by Biolan) with a commercial organic liquid fertilizer by Biolan as a supplemental fertilizer are tested. In the same greenhouse but in a separate test the effect of sea algal on the production of sweet pepper is studied. The treatments of the second phase are selected according to the results of the first phase. MTT Agricultural Engineering is responsible for planning the use of liquid fertilizer and installations of the instruments needed and participates in the reporting. The University of Helsinki is responsible for management of the test in co-operation with the enterprises.
MTT Laukaa Research and Elite Plant Station clarifies in co-operation with the University of Helsinki the effects of mycorrhiza inoculation on the growth and yield production of selected organic spices and lettuce. In the test there are four medias developed by Kekkilä. One of them is optimised in the respect of the function of mycorrhiza transplant and actually transplanted with it. The others are: one traditional, one under development and one is optimised in the respect of the function of mycorrhiza transplant but without mycorrhiza. In 2003 the use of mycorrhiza is clarified in pot lettuce, parsley, basil, balm, thyme and coriander. The media is blended with 5% of transplant by volume. The University of Helsinki carries out analyses related to nutrients, germination, growth and production. During the growth physical properties of the media are measured. MTT clarifies issues related to the function of mychorriza, such as colonization in the root. The function of mycorrhiza is also measured as the phosphorus content of the leaves, because in a functioning symbiosis the phosphorus content of the leaves is increased pronounced.
After the test the University of Helsinki and MTT Plant Production Research estimates compatibility of the media and growing methods with mycorrhiza. The medias in the second phase of the study are selected based on the experience gathered in the first phase of the study. Mycorrhiza tests are carried out with these medias at least in sweet pepper, maybe also in greenhouse strawberry and spices for second time. MTT produces larger amounts of the mycorrhiza inoculum (scale-up) to provide a larger use of the mycorrhiza.