Sugarbeet yield and nitrogen use efficiency with preplant broadcast, banded, or point-injected nitrogen application.

摘要

Rising fertilizer costs and environmental concerns have heightened the need to improve N management in furrow-irrigated sugarbeet (Beta vulgaris L.) production. A study was conducted at two Wyoming locations to compare the effect of different preplant N placement strategies on yield, quality, and N use efficiency (NUE). Nitrogen was applied at rates from 0 to 358 kg ha-1 using three different placement strategies: broadcast and incorporated (BI), knife-banded (KB) 18 cm from the seed row, or point-injected (PI) 8 cm from the seed row. Placement had no consistent effect on root sucrose content. Point injection produced the greatest maximum predicted yield (Y< sub>MAX) in five of six N responsive site-years with an average advantage of 603 and 975 kg ha-1 sucrose compared to BI and KB, respectively. The amount of N required for maximum sucrose yield ranged from about 10 to 100 kg N ha-1 less for PI than for other placement methods. For site-years where a response to N occurred, NUE was highest with PI, intermediate with KB (19% less than PI), and lowest with BI (28% less than PI). The advantage of PI, which placed N closer to the seed row than the other methods, was attributed to less leaching and greater uptake of N during early growth stages when the sugarbeet has little lateral root development. It was concluded that PI is an effective tool for maintaining high N concentration in the root zone for optimum early vegetative growth at lower N rates, thus improving NUE in sugarbeet production.