Soil Acidity Management By Surface Liming on No-Tillage Wheat Production.

In tropical regions, crop production has been limited by soil acidity and low exchangeable base availability. In order to improve the soil chemical properties on no-tillage wheat production system, the surface liming stands out among the most effective efficient strategies, however, carbonate reaction in subsurface soil layers is uncertain. The aim of this study was to evaluate the effect of lime surface application on wheat root growth and grain yield in a long-term experiment under no-tillage system. A field experiment has been conducted since the agricultural year 2002/2003 in a sandy clay loam, kaolinitic, thermic Typic. Treatments included four dolomitic limestone rates (0, 1000, 2000, and 4000 kg ha–1) which were applied in establishment of the experiment (2002), and re-liming in 2004 and 2010, when the standard treatment (calculated rate) reached base saturation = 50%. About 36 months after the last application, soil pH, exchangeable Ca2+ and Mg2+, and phosphorus raised in soil profile. The magnitude of carbonate reaction ranged according to lime rate and soil depth. The highest rate increased 1.1, 0.4, and 0.2 pH in 10-20, 20-40, and 40-60 cm soil layers, respectively. The benefits of surface liming on soil chemical attributes provided increases about 150% in wheat root length density below the depth of 20 cm. In addition, the wheat grain yield increased from 311 to approximately 3,000 kg ha-1. In general, the surface liming in tropical soil was essential by increased availability of essential nutrients, which provided better conditions for root growth, increasing the efficiency of use of water by wheat.