Effects of nitrogen fertiliser on the growth, development and yield of maize (Zea mays L.) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Plant Science

Abstract

Maize has been grown in New Zealand for over a century. The traditional grain growing district has been Gisborne, where suitable environmental conditions prevail. Over recent years there has been a rapid expansion of maize production for grain, silage and greenfeed. For example, in the 1970/71 season (NZMAF estimates), 12,000 hectares of maize was grown for grain while in 1962/63 only about 3,000 hectares were grown; in the 1971/72 season 18,600 hectares were involved in grain production. Respective estimates for the 1972/73 and 1973/74 seasons were 16,300 and 17,800 hectares. Furthermore maize growing has now extended far beyond Gisborne with the Waikato, Bay of Plenty and Hawkes' Bay districts being regarded as major grain producing areas of New Zealand. Further south in the Manawatu and Canterbury high yielding crops of maize are also being grown for silage and greenfeed under suitable environmental conditions. Along with the upsurge in maize growing in these districts there has been the need for more agronomic information (Gooding, 1972) on the yield response, in terms of grain and total dry matter production; on the appropriate rate of nitrogen application and on the timing of the application for maximum response under the prevailing environmental conditions. With more maize being utilised in intensive animal production enterprises (Jagusch and Hollard, 1974) the quality of the dry matter produced assumes greater importance.