Quantitative observation on the root system of various crops growing in the field

Abstract

1. Rice (flooded), wheat, maize, soybean, potato, and sugarbeet were grown in fields with and without nitrogen application, and various traits of the root system were quantitatively measured at the growth stage when the root system had fully developed. 2. The total length of the whole root system per unit field area ranged from 21 (potato) to 86 (wheat) km-m−2. The total surface area was only 22 m2-m−2 in potato and about 90 m2-m−2 in rice, wheat, and maize. The total volume was in the range of 1.8 (potato) to 13 (maize) liters -m−2. The mean diameter was 0.56 mm in maize and 0.33-0.39 mm in the other crops. These values generally increased when nitrogen was applied. 3. The root system was shallower in rice, and deeper in maize than in the other crops. Soil depth where 90% of the roots were distributed was 23 cm in rice, 35-38 cm in potato and soybean, 48-51 cm in sugarbeet and wheat, and 59 cm in maize. 4. The root density (value of various root traits per unit soil volume) in the upper soil layers and the largest density observed among various soil positions were larger in rice and wheat, and smaller in potato and soybean. These values slightly increased when nitrogen was applied. 5. Root length, surface area, and volume per unit dry weight averaged over the whole root system were 160-460 m-g−1, 0.28-0.56 m2-g−1, and 30-57 cm3-g−1, respectively. These values were larger in sugarbeet than in the other crops. 6. The density of various root-traits as well as the mean diameter decreased with the increase of the soil depth. The distribution pattern, however, differed among the root traits and also among the crops. The reduction rate in the soil profile was larger in rice and potato, and smaller in maize and sugarbeet. © 1990 Taylor & Francis Group, LLC.