Effects of Short-term Tillage of a Long-term No-Till Land on Crop Yield and Nutrient Uptake in Two Contrasting Soil Types

Pre-seeding tillage of long-term no-till (NT) land may alter crop production by changing the availability of some nutrients in soil. Effects of short-term (4 years) tillage (hereafter called reverse tillage [RT]) of land previously under long-term (29 or 30 years) NT, with straw management (straw removed [SRem] and straw retained [SRet]) and N fertilizer rate (0, 50 and 100 kg N ha-1 in SRet, and 0 kg N ha-1 in SRem plots), were determined on plant yield (seed + straw, or harvested as forage/silage at soft dough stage), and N and P uptake in growing seasons from 2010 to 2013 at Breton (Gray Luvisol [Typic Cryoboralf] loam) and from 2009 to 2012 at Ellerslie (Black Chernozem [Albic Argicryoll] loam), Alberta, Canada. Plant yield, N uptake and P uptake tended to be greater with RT compared to NT in most cases at both sites, although significant in a few cases only at Ellerslie. On average over both sites, RT produced greater plant yield by 560 kg ha-1 yr-1, N uptake by 5.8 kg N ha-1 yr-1, and P uptake by 1.8 kg P ha-1 yr-1 than NT. There was no consistent beneficial effect of straw retention on plant yield, N uptake and P uptake in different years. Plant yield, N uptake and P uptake increased with N fertilization at both sites, with up to the maximum rate of applied N at 100 kg N ha-1 in 3 of 4 years at Breton and in 2 of 4 years at Ellerslie. In conclusion, our findings suggested some beneficial impact of occasional tillage of long-term NT soil on crop yield and nutrient uptake.