The effects of nitrogen, phosphorus, potassium, and lime on the growth and canning yield of clingstone peaches

Abstract

The responses in canning yield and tree growth obtained from clingstone peaches (CV. Golden Queen) to fertilizers applied in factorial combinations were measured for 19 years at Tatura, Victoria. During the first eight years, the treatments involved ammonium sulphate, superphosphate, and potassium sulphate. Then a fourth factor, lime, was added, and included in the study for four years. For the final period of seven years, the experimental design was modified, in that all trees were limed, potassium sulphate was deleted, and applications of ammonium sulphate were re-arranged. The fertilizer combination that gave the greatest tree response was an application of 3 lb ammonium sulphate plus 4 lb superphosphate to each tree (at bud swell), and then in mid-summer an extra 3 lb ammonium sulphate. The main effects of nitrogen, phosphorus, and lime were to increase both yield and growth, while the main effect of potassium was to depress them (usually it was not large enough to be proved significant). The main effect of splitting the total application of ammonium sulphate was to increase yield through larger fruit size, but there was no effect on growth. The responses were independent and additive. Ammonium sulphate strongly acidified the soil, and this caused manganese toxicity, which was alleviated by liming.