Fertilisation azotée, phosphatée et potassique dans la production du bleuet nain sauvage
Lafond, J. (2020). Fertilisation azotée, phosphatée et potassique dans la production du bleuet nain sauvage. Canadian Journal of Soil Science, [online] 100(2), 99-108. http://dx.doi.org/10.1139/cjss-2019-0087
Plain language summary
Several studies have demonstrated the importance of nitrogen (N) fertilization in improving the productivity of lowbush blueberry (Vaccinium angustifolium Ait.). This element is of particular importance because it helps to increase plant size and the number of flower buds, and therefore the number of fruit. However, little information is available on the effects on this crop of phosphorus (P) and potassium (K), the other two elements generally found in formulations of commercial fertilizer. This crop is also unique because its production cycle is two years long. The first year consists of vegetative growth and the formation of flower buds. Fertilizers are also applied to the soil surface during the first year of the cycle. In the second year of the cycle, the fruit is harvested over a period of three to four weeks in August. The objectives of the project were to determine the impact of NPK fertilization on soil chemical properties and agronomic parameters. Treatments consisted of four rates of N (0–90 kg N ha-1), two rates of P (0 and 20 kg P2O5 ha-1) and four rates of K (0–90 kg K2O ha-1). All combinations of NPK were tested, for a total of 32 fertilizer treatments. Experimental layouts were used in six commercial blueberry fields in the Saguenay-Lac-St-Jean region. Soil analyses showed that the pH decreased after applications of N. This decline is beneficial to the blueberry plant since it prefers acidic soil for its development. Accumulations of P and K were measured at the soil surface after applications of phosphorus and potassium fertilizers. The results showed that the fertilizers provided excessive levels of nutrients, which were not used by the plants. Fruit yields increased by 43% after applications of N. An application of 20 kg P2O5 ha-1 appeared necessary to maximize yields when N inputs exceeded 50 kg ha-1. A rate exceeding 30 kg K2O ha-1 lowered fruit yields by up to 24% when combined with a rate higher than 60 kg N ha-1. This study showed the positive effects of nitrogen fertilization on crop productivity improvements. However, P and K fertilizers should be used in accordance with foliar analysis results in order to maintain the plant’s nutritional balance.
Several studies have shown how nitrogen (N) fertilizers can increase blueberry productivity. However, available information on phosphorus (P) and potassium (K) is limited. This study evaluated the impact of NPK fertilizers on the soil chemical properties and agricultural factors. Plots received four rates of N (0–90 kg N ha−1), two rates of P (0 and 20 kg P2O5 ha−1), and four rates of K (0–90 kg K2O ha−1). A randomized complete blocks design was used at six sites in Saguenay-Lac-St-Jean. Following fertilizer application, pH decreased 0.1 unit in the surface soil and 0.2 units in the 5–30 cm deep soil layer. P and K accumulations were measured in the surface soil. Yield also increased 43% after the N application. Application of 20 kg P2O5 ha−1 appeared necessary to maximize yield when N fertilization was over 50 kg ha−1. Application of over 30 kg K2O ha−1 decreased the fruit yield up to 24% when combined with a >60 kg N ha−1. Translated by the Editor.