Exploring the synergism between surface liming and nitrogen fertilization in no-till system

Abstract

Surface liming to correct soil acidity may have limited effectiveness in subsurface layers in no-till systems (NTS). The possibility of downward movement may be increased when liming is combined with fertilization with urea (ammoniacal N), as NO3– formed by nitrification of NH4+ can form ion pairs with exchangeable Ca2+ and Mg2+. Liming can also increase the nitrogen use efficiency (NUE) of crops and reduce dependence on soil N. In this work, we investigated the effects of surface application of lime under NTS and N topdressing on soil chemical properties and the nutrition, productivity, and NUE of maize (Zea mays L.) and upland rice (Oryza sativa L.). The treatments comprised four lime rates applied superficially (0, 1,500, 3,000, and 6,000 kg ha–1), and absence (–N) or presence of N fertilization (+N) as urea by topdressing. The treatments were applied during two agricultural years (2011/2012 and 2012/2013), with maize in the first crop season and upland rice in the second crop season. At 18 mo after liming, the application of 6,000 kg lime ha–1 significantly improved the chemical attributes of the soil (pH, soil organic matter (SOM), K, Ca2+, Mg2+, and base saturation [BS]). The application of urea increased the mobility of Ca2+ and Mg2+ to greater depths. The combination of 3,000 kg lime ha–1 with N fertilization synergistically increased the nutrition (N, P, and S), grain yield, and N-related efficiency indexes in the maize and upland rice crops.