Micronutrient concentrations in soil and wheat decline by long-term tillage and winter wheat–pea rotation

Abstract

Tillage plays a major role in nutrient dynamics under dryland cropping systems, but there remains uncertainty regarding the long-term impacts of tillage on nutrient availability. The objective of this study was to examine the influence of tillage intensity and timing on micronutrient concentration of soils and winter wheat (Triticum aestivum L.) under dryland winter wheat–pea (Pisum sativum L.) or WW-P rotation. The treatments included moldboard tillage in fall (FT) and spring (ST), disk/chisel tillage (DT), and no-tillage (NT). The concentrations of Mehlich III extractable boron, manganese, zinc, copper, and iron in soil were unaffected by the tillage methods; however, a significant decline in extractable zinc in the top 10 cm soil was observed compared to an adjacent undisturbed grass pasture (GP) (NT: 2.3 mg kg−1 vs. GP: 6.0 mg kg−1). In the upper 10 cm soil surface, NT (123 mg kg−1) maintained the extractable manganese concentration with GP (175 mg kg−1) whereas FT (97 mg kg−1), ST (92 mg kg−1), and DT (113 mg kg−1) had lower manganese than GP. Soil pH declined in the upper 10 cm under NT more than in the rest of the WW-P treatments. The results suggest NT can play a vital role in sustaining micronutrient availability due to decreased soil pH and the greater amount of organic matter within the surface soil of NT compared to other tillage methods.