Abstract
Producer price of sugar beet had been determined by quantity base such as harvested root weight until 1985, while it was changed to quality and quantity base expressed by sugar weight in harvested root since 1986. This change has encouraged sugar beet farmers low input of nitrogen fertilizer. We estimated the amide nitrogen contents of sugar beet at Tokachi Area, Hokkaido, Japan, using Landsat TM data in 1986. The following equation were derived to estimate the amide nitrogen contents successfully: AN = -0.321TM3 + 10.743 …① (n=16, r=0.78**) where AN is amount of amide nitrogen (meq/100g) and TM3 is Band3 derived Landsat TM data. The excess and deficiency of nitrogen absorption amount was also estimated from amide nitrogen contents and equations (②～⑤), and a sectional map was made. AS1 = AN x 14.0067 x 10-5 …② AS1: amount of amide nitrogen production per 1kg root fresh weight (kg/kg root fresh weight) 14.0067: atomic weight of nitrogen AS2 = R x AS1 …③ AS2: amount of amide nitrogen production per 10ares (kg/10a) R: root weight (kg/10a) EN = 4.1687 + 18.2451 x ln (AS2+ 1) …④ EN: estimated nitrogen absorption amount (kg/10a) NEL = (19.0 - EN) / 0.78 …⑤ NEL: estimated excess and deficiency of nitrogen absorption amount (kg/10a) 19.0kg/10a: ideal nitrogen absorption amount 0.78: recovery rate of nitrogen fertilizer application These results indicates that estimation of amide nitrogen contents and nitrogen excess or deficiency by Landsat TM data are useful to improve productivity sugar beet by appropriate fertilization, for example.
