U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska
Date of this Version
January 1982
Abstract
Tillage practices can influence crop root development. Root distributions were determined for wheat (Triticum aestivum L.) grown in a wheat-fallow rotation during the 1977-1978 winter wheat crop year on an Alliance silt loam (Aridic Argiustoll). The fallow tillage treatments were plow, subtillage, and chemical (no tillage). Each tillage treatment was split into subplots for N application of 0 or 45 kg/ha. Rooting density was determined by washing the roots in soil cores 7.6 cm in diam by 15 cm long extracted to depths of 90, 105, and 120 cm on 28 Mar., 2 May, and 8 June 1978, respectively. After root length was determined, roots were dried and weighed. Soil penetration resistance was determined with depth in the soil by inserting a penetrometer horizontally 4 cm into the soil at vertical intervals of 10 cm from the surface. Root weight was greatest for the chemical treatment (46 mg/dm3) and least for the subtillage treatment (26 mg/dm3). Approximately 62% of the total root mass was in the upper 30 cm of soil with maximum rooting depth greater than 120 cm for all treatments by 8 June 1978. Root development was limited by the alluvial horizon at a depth of about 25 to 40 cm. Visual observations also showed some root resistance by tillage shear plane at 10 cm. Nitrogen fertilization did not significantly change the rooting pattern; however, the N-by-tillage interaction for root weight was significant at the second sampling date-the subtillage treatment showed a positive response to added N, while chemical and plow treatments showed a negative response. Wheat yields were not significantly influenced by fallow tillage or N. This indicated that root development occurring above and below the resistant layer was sufficient to supply the plan; with its water and mineral needs.
Comments
Published in Agronomy Journal, vol. 74, January-February 1982.