The effect of the annual application of 80 kg P25-1 or a single dose initial buildup rate of 400 kg P25-1 phosphorus fertilization in the form of reactive Algerian rock phosphate (ground to a fine powder, with good natural P solubility) or superphosphate produced from Kola phosphate was investigated in two 5-year field experiments set up on moderately/strongly acidic soil. The P supplies at the beginning of the experiment were poor to moderate for the chernozem brown forest soil in Kompolt and moderate to good for the pseudogley brown forest soil in Szentgyörgyvölgy. Among the methods examined, the P-supplying ability of the two P forms was best characterized by the H2O-P soil P test. The plant availability of the phosphorus applied in the form of rock phosphate was overestimated by the AL method and underestimated by the Olsen method. During the first 5-year cycle of experiments, the two P forms and the two P fertilization systems proved to be equally effective in terms of both the main yield and the quantity of phosphorus taken up. The P utilization was 2-3 times as great on the Kompolt soil (7-10%) as on the better supplied Szentgyörgyvölgy soil (2-5%). The fact that positive P balances were found in the P treatments even in the 5th year suggests that the fertilizer P remaining in the soil would be further utilized in these treatments if P fertilization was discontinued. The application of Algerian rock phosphate did not result in an increase in the readily available (LE, Lakanen-Erviö) Cd or Cr contents of the soil. In response to the addition of superphosphate made from Kola phosphate, however, higher LE-Sr concentrations were detected. On moderately acidic Hungarian soils the excellent natural solubility of Algerian rock phosphate could make it an excellent substitute for the more expensive superphosphate, which further acidifies the environment, and for complex or mixed mineral fertilizers with a high phosphorus content. In keeping with the practice in other countries, the use of one and a half times or twice the rate normal for water-soluble P forms is justified when rock phosphate is applied on moderately or strongly acidic soils. Only the powder form of sedimentary, reactive rock phosphates containing less than 20 mg•kg-1 Cd can be considered environmentally safe for direct application.
|Translated title of the contribution||Evaluation of the agronomic and environmental aspects of the direct application of Algerian rock phosphate to acidic soils in field experiments in Hungary|
|Number of pages||18|
|Journal||Agrokemia es Talajtan|
|Publication status||Published - Dec 1 2012|
ASJC Scopus subject areas
- Agronomy and Crop Science
- Soil Science