Effect of tillage on macronutrients in soil and wheat of a long-term dryland wheat-pea rotation

Abstract

Tillage is known to significantly affect crop residue decomposition and soil nutrient dynamics, but the impacts of tillage on soil and plant macronutrients concentration with time have not been reported. This study was conducted (i) to assess the influence of tillage timing and intensity on soil and wheat (Triticum aestivum L.) macronutrient concentration of a winter wheat-dry pea (Pisum sativum L.) rotation (WW-P) under a dryland cropping system, and (ii) to compare macronutrients in the tillage treatments with a nearby long-term grass pasture (GP). The tillage treatments were fall tillage (FT), spring tillage (ST), no-tillage (NT) and disk/chisel tillage (DT/CT). Soil samples from 1995, 2005, and 2015 were analyzed to determine the concentration of soil organic carbon (SOC), total N and S, Mehlich III extractable P, K, Ca, and Mg, and soil pH. The impact of tillage on soil macronutrient concentration was evident after 52 years of WW-P. As a result, greater concentration of SOC, total S, and extractable P, and K were observed under NT than under FT or ST. The WW-P plots lost 28, 46, and 67% of SOC, Mg, and S, respectively, in the top 10 cm of soil compared with the GP plots, whereas the NT plots were the only plots in WW-P to maintain a P concentration (99 mg P kg−1) comparable with GP plots (102 mg P kg−1) at the same depth. The results indicated that NT could be beneficial to recharge the soil nutrient pool over time compared to FT or ST.