Residual Effects of Potassium Placement and Tillage Systems for Corn on Subsequent No-Till Soybean
Little is known about K fertility management for no-till (NT) soybean [Glycine max (L.) Merr.]. This study was conducted to evaluate the residual effects of K application rate, timing, and placement for corn (Zea mays L.) in various tillage systems on subsequent NT soybean. Field experiments involving a corn–soybean rotation were conducted from 1998 to 2000 on long-term NT fields with medium or high exchangeable soil K levels near Kirkton and Belmont, ON, Canada. In the corn year, treatments included the combinations of three fall K rates (0, 42, and 84 kg ha−1), spring K rates (two rates differing by 42 kg ha−1), and three tillage systems [NT, zone till (ZT), and moldboard plow (CT)]. Both CT and ZT (also known as intermittent tillage systems) reduced soil K stratification relative to continuous NT. Trifoliate leaf K concentrations increased with residual fall and spring K applications in most site-years. Average soybean yield significantly increased by 8.3% with the application of 84 kg K ha−1 in fall plus 42 to 50 kg K ha−1 in spring to previous corn only on medium-testing (K < 100 mg L−1) soils. Residual tillage had no effects on leaf K or yield of NT soybean. Application of fall and spring K fertilizers to corn was equally beneficial for subsequent soybean in either continuous or intermittent NT systems. Furthermore, soil K stratification and the residual effects of tillage and K placement method were not major production issues for narrow-row NT soybean in these growing seasons.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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