Tomato root growth is influenced by tillage, cover cropping, and nitrogen fertilization

Abstract

The influence of tillage [no-till (NT) vs. moldboard plowing (MP)], cover crop [hairy vetch (Vicia villosa Roth) (HV) vs. no hairy vetch (NHV)], and N fertilization (0 and 180 kg · ha-1 N) on root distribution and growth rate of tomato (Lycopersicon esculentum Mill.) transplants was examined in the field from May to August in 1996 and 1997. Experiments were conducted on a Norfolk sandy loam (fine-loamy, siliceous, thermic, Typic Kandiudults) in central Georgia. Root growth was estimated every 1 to 2 weeks with minirhizotron tubes installed in the plot. Roots were well distributed at soil depths between 1 and 58.5 cm and a maximum root count of 3.14 roots/cm2 soil profile area was found at 19.5-cm depth with MP and no N fertilization in 1996. In general, NT with HV or with 0 kg · ha-1 N increased root proliferation at a depth of 6.5 to 19.5 cm, while MP with 180 kg · ha-1 N increased root proliferation at greater depths. Total root count between 1 and 58.5 cm was not influenced by management practices, but increased linearly at rates of 0.35 roots/cm2 per day from 20 June to 11 July 1996, and 0.03 roots/cm2 per day from 16 May to 5 Aug. 1997. Root growth thereafter was minimal. Because of the higher temperature during early development, growth rate and number of roots were greater in 1996 than in 1997. Superior moisture conservation, accompanied by increased N availability, may have increased root proliferation in the surface soil in NT with HV or with 0 kg · ha-1 N compared with NT with NHV or with 180 kg · ha-1 N, and MP with or without HV or with or without N fertilization. Root growth, however, was not related with aboveground tomato yield.