Nitrogen fertilizers for coffee - I: red latosol transition to clay red yellow latosol

The following sourcesof nitrogen were studied in a field experiment with coffee plant: Ammonium nitrate with lime (AND, Ammonium sulphate, Chilean nitrate and urea, in doses corresponding to 75, 150, 225, and 300 kilograms of element per hectare. The soil was a Red Latosol transition to Clay Red - Yellow Latosol from the area of Campinas County, State of São Paulo. The experiment was installed in March, 1957 and the yield records collected from 1959 to 1969. The total annual doses were splited into 2, 4, 5, and 9 applications until 1963/64, and into 1, 2, 3, and 4 applications from that year on to the end of the experiment. Shortly after the 1969 picking, the plants were cut down to the height of about 50 centimeters, for renewing of the aereal parts. In 1972 a series of soil and leaf samples were taken for analysis and study of the residual effects of the fertilizers. The yields showed a very significant increase with increasing doses of nitrogen. ANL and ammonium sulphate were significantly superior to the urea and Chilean nitrate. The ammonium sulphate was superior to ANL during several years but in the last few years of the experiment this situation was reversed, with ANL giving higher yields. The mineral analysis of the fruits showed that the nitrogen, iron, and manganese contents varied with the source of nitrogen employed. The use of ammonium sulphate, urea and ANL lowered the pH of the soil; the manganese and aluminum content of the leaves increased when ammonium sulphate or urea was used.