Published in Scientific Papers. Series A. Agronomy, Vol. LXV, Issue 1
Written by Nicoleta MĂRIN, Mihail DUMITRU, Carmen SÎRBU
Researches carried out in the long-term experimental fields of the agricultural research stations from Valu lui Traian, Turda and Lovrin (experiments started in 1967) and Teleorman and Secuieni (started in 1976 and 1975) highlighted that phosphorus fertilization in doses of 40, 80, 120, and 160 kg/ha led to statistically assured increases for wheat and maize production and to an increase in the level of soil supply with available phosphorus. Currently, in Romania 65.41% of the country's agricultural area are characterised by small, very small and extremely low values of soil available phosphorus content. The trend is worsening due to the low level of using phosphorus fertilizers (on average, between 2012-2019, 13 kg P/ha were applied, the deficit being 26.46 kg/ha). Therefore, it is required a minimum dose of phosphorus of 80 kg/ha, while over 120 kg P/ha are needed to ensure a better level of soil phosphorus content. Higher doses ensure not only higher yields but also better use of nitrogen-based fertilizers or nitrogen and potassium-based fertilizers. In all long-term experiments (39-51 years) high doses of phosphorus (over 120 kg P/ha) led to an increase in soil phosphorus stock at a very high level of supply in all experimental stations. Every 100 kg P/ha increases annually the soil phosphorus content with 0.59-1.90 mg/kg. Long-term (39- 51 years) fertilization with phosphorus, regardless of dose (up to 200 kg P/ha) did not lead to statistically assured increases of heavy metals (Cd, Cu, Pb, Zn, Mn) content in soil.
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