Strategies to alleviate pH stratification and subsurface acidity in a no‐tillage system

Abstract

AbstractSome no‐tillage systems necessitate amelioration of subsurface acidity. A 2‐year field trial was conducted on a no‐tillage sandy loam Cambisol, with a pH(KCl) of 4.20 in the 10‐ to 30‐cm depth. The aim was to evaluate one‐time tillage, calcitic lime forms, and lime plus gypsum combinations on soil chemical parameters, and wheat (Triticum aestivum L.) and canola (Brassica napus) production. Incorporation of lime (1.67 Mg ha−1) through one‐time chisel plowing increased soil pH(KCl) and soil exchangeable calcium in the 20‐ to 30‐cm depth by 9.1% and 210.1%, respectively, after 18 months. Conventional one‐time tillage treatments resulted in 15.0%–18.1% reduced wheat seedling establishment in the subsequent season. Surface‐applied hydrated lime (1.56 Mg ha−1) and microfine pelletized lime (1.75 Mg ha−1) both caused over‐liming (pH(KCl) > 6.5) effects in the 0‐ to 5‐cm depth after 6 months, which attenuated from 12 to 18 months. Surface‐applied lime (1.67 Mg ha−1) showed a 2.9% and 5.6% pH(KCl) reduction in the 10‐ to 20‐cm and 20‐ to 30‐cm depths, respectively, after 18 months. While combined surface application of lime (0.55 Mg ha−1) plus gypsum (1.25 Mg ha−1) showed a 3.7% and 0.5% pH(KCl) reduction in the 10‐ to 20‐cm and 20‐ to 30‐cm depths, respectively, after 18 months. Wheat (year 1) and canola (year 2) yield and seed quality parameters were unaffected (p > 0.05) by the treatments. Subsurface acidity amelioration in no‐tillage systems is best achieved through chisel lime incorporation or combined surface application of lime plus gypsum on moderately or highly weathered soils.