Response of barley yield and yield components to nitrogen rate under low and high input management systems

Abstract

Increasing rates of nitrogen (N) fertilization may increase disease and lodging in cereals. As a result, use of high-input management (HIM) systems, which use growth regulators to control lodging and fungicides to control disease, may allow a greater increase in yield due to N fertilization than occurs in conventional low input management (LIM) systems. The study was conducted to determine the influence of two management systems on the response of yield and yield components of barley (Hordeum vulgare L.) to N fertilization and to determine if use of a HIM system was cost-effective under southern Ontario growing conditions. Barley, cv. Leger, was grown at eight rates of N fertilization under either HIM or LIM systems in 10 environments in southern Ontario. The response of grain and straw yield to N rate was not significantly different between management systems; however, the maximum economic yield occurred at a significantly higher N rate under the HIM system (90 kg N ha−1) than under the LIM system (71 kg N ha−1). The number of heads m−2 was higher under the HIM system than under the LIM system whereas the reverse was true for grains head−1. Increased N rate resulted in increased 1000-grain weight under the HIM system but had little influence on 1000-grain weight under the LIM system. Over the duration of the study, the increased revenue obtained under the higher input management system was generally less than the cost of the added inputs used, emphasizing the need for threshold values which producers can use to determine when crop protection inputs are likely to be cost-effective. Key words: Fungicide, growth regulator, seeding rate, nitrogen, barley