Impact of tillage and banded starter fertilizer on maize root growth in the top 25 centimeters of the soil

There is little information about root growth response to tillage and starter fertilization in cool temperate regions. Maize (Zea mays L.) root morphology and distribution at anthesis were studied in 1997 and 1999 at two sites in the Swiss Midlands on a loamy silt and a sandy loam soil. The effects of tillage system, conventional tillage (CT) vs. no-tillage (NT), and starter fertilizer (SF) banded to one side of the seed row were evaluated. Roots were determined in soil cores taken 9.5 cm on each side of the seed row and 25 cm deep. The overall root length density (RLD) was significantly greater under CT than under NT on the loamy silt soil but not on the sandy loam soil. In NT, RLD tended to be greater than in CT in the uppermost 5 to 10 cm of the soil but less in deeper soil. Mean root diameter (MD) under CT was smaller than under NT for both years and sites. In 1997, banded SF (BSF) improved RLD in the SIT bands compared with the opposite side of the seed row; in 1999, this effect happened only in the uppermost soil layers (0 to 5 cm) in NT. Banded SF tended to increase MD in three combinations of year and site and to decrease it in Schafisheim 1999. Overall, this research indicates that the effects of tillage and BSF on root growth of maize at flowering were in accordance with the previous findings on early root growth. However, root growth response to tillage and SF is complex and often a function of year, soil type, and depth.