Tests of long-term residues of phosphorus fertiliser

✍ Scribed by Philip E. Sparrow; Richard D. Russell

• Publisher: John Wiley and Sons
• Year: 1977
• Tongue: English
• Weight: 370 KB
• Volume: 28
• Category: Article
• ISSN: 0022-5142
• DOI: 10.1002/jsfa.2740280806

✦ Synopsis

Abstract

Four experiments with maincrop potato were done in 1973 to compare the residual values of two amounts of four forms (Dicalcium phosphate, Superphosphate, Gafsa— Ground mineral phosphate, Basic slag) of phosphorous fertiliser given from 1951 to 1971. The residues were evaluated by test dressings of nil, 37.5 and 75 kg/ha P~2~O~5~ as superphosphate; to make the results as comparable as possible at each site the new P was thoroughly incorporated into the soil. Residues increased yields on all sites; effects were small except at Rosemaund Experimental husbandry farm (EHF) where residues alone increased yields by 8.6 t/ha. Apart from Ground mineral phosphate, which had little effect except at Rosemaund, yield differences resulting from forms of P fertiliser were small. Apart from at Rosemaund EHF the rate of response to the freshly applied phosphate was unrelated to the available soil P. In terms of fresh dressings residues were equivalent to about 8 % (80 kg P~2~O~5~ha) of accumulated total dressings.