Agronomijas v stis - Latvijas Lauksaimniecības universitāte

At present the highbush blueberry is being cultivated in many countries of the world. Also inPoland, since many years the people have been interested in growing them, however the plants didnot grow well in the field. In the sixties of past century there was an idea to cultivate the plants inconcrete rings or in deep holes, covered with plastic and filled with acid peat or with the forest soilmixed with acid peat. In such conditions the plants grew very well and gave a good yield. Theobservation of those plants convinced us that the blueberries can be cultivated in our climatic andsoil condition. However the method of growing plants in concrete rings or deep hols could not berecommended for commercial cultivation from economical reasons. We started to look for thereasons, why in Poland the blueberries do not grow well in the open field, like it is in the USA andmany other countries.In seventies of past century some experiments were started to explain this phenomenon.Materials and MethodsIn 1976 one of the first experiments was set on the Experimental Field belonging to the Dept ofAgricultural Chemistry of Warsaw Agricultural College (SGGW) in Skierniewice. The plots of thisExperimental Field are being characterised by constant fertilization, since 1923, with the somemineral compounds. ( 0-control, CaNPK, NPK, PK, PN and KN). No organic fertilization is beingused. The experiment with blueberries was set on plots with mineral fertilizers and characterised bylow pH of soil. On those plots the nitrogen is being used only as ammonium sulphate.The soil on whole Experimental Field was drained, and belongs to the IV class according to Polishnomenclature. The same way of fertilization influences on the content of single compounds in thesoil, and differentiates its pH.Results and DiscusionBy planting the blueberry on such plots, it was possible to conclude after some years, what is theinfluence of single compounds on the growth and cropping of two blueberry cultivars – Bluecropand Jersey, used in this experiment (Table 1.)Table 1. Soil pH (KCl) and concentration of the nutrients (mg 100 g -1 soil)Treatments pH P K Ca Mg0 4.4 2.7 5.6 29.0 3.2Ca NPK 4.5 11.2 17.8 34.0 3.4NPK 3,6 10.8 13.5 14.1 2.1PK 4.5 11.9 20.2 25.0 2.6PN 3.5 10.6 4.7 15.2 2.0KN 3.7 3.3 13.7 13.8 2.1• After 60 years of treatmentThe main aim of this experiment was also to find out what are the possibilities of growingblueberries not only on light sandy soils and but also on more fertile soil of low pH 3,5 – 4,0 (Table2.) The method of determination of soil pH in USA and in Poland are different and this causedgreat misunderstanding in choosing the right soil for blueberry cultivation in our country. In Polishchemical stations pH is determined in KCl what means, that most suitable for blueberries soil withpH 3,5 – 4,0 ( this value according to American method of pH determination would be pH 4.0 –5.0). The Polish IV class soil ( the type which is dominated in Poland ) might be suitable forblueberry, in case that the other physical conditions required by this plant are proper. Those typesof soil are more fertile, do not require so much of irrigation in comparison to light sandy soil.Table 2. Average yield of two cultivars of highbush blueberry (kg/plant) (1988 – 1991 ).Treatments Bluecrop Jersey0 0.94 a 0.68 aCa NPK 0.90 a 1.34 bNPK 3.47 c 2.38 cPK 1.26 a 0.76 aPN 2.09b 1.53bKN 2.99 c 1. 67 b120