Diagnostics of nutrient status of soil for highbush blueberries in Latvia, 2014-2018

Highbush blueberry (Vaccinium corymbosum L.) cultivation in recent years is a rapidly growing agricultural sector in Latvia. In general, blueberry plantings are located in extracted raised bogs on sphagnum peat and also on well-drained acid mineral soils with a high content of organic matter. This study was conducted to find out the soil nutrient status of blueberry crop cultivated on peat and mineral soils in Latvia in order to identify key issues potentially limiting growth and productivity, as well as to quantify the differences between soil types. In total, 65 peat and 75 mineral soil samples from different blueberry plantations were collected during 2014-2018 and tested on the plant available nutrients (N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu, Mo, B), soil pH/KCl and electrical conductivity (EC). The study revealed a deficiency of N and B in most of the analysed soils. Less than 20% of the results in the optimum range indicated N as the most deficient nutrient regardless of soil type. Besides, low levels of S, Zn and EC were typical for mineral soils, Mo-for peat soils. Significantly higher pH levels and mean concentration of P, K, Fe and Mn was found in mineral soils, while S, Cu and EC in peat soils. The high potential of Mn toxicity for blueberries in mineral soil was demonstrated by 70% of excessive results. In general, the present study showed that blueberry plantations on peat soils had a better supply of nutrients, as 59%/47% of all nutrient values for peat/mineral soils, respectively, were in optimal range. Twice more significant positive medium-to-high correlations between chemical parameters in peat soils compared to mineral soils also suggested on higher level of blueberry fertilization in the plantations established in extracted peatlands.