Soil total carbon and nitrogen and crop yields after eight years of tillage, crop rotation, and cultural practice

Upendra M Sainju,Andrew W Lenssen,Brett L Allen,William B Stevens,Jalal D Jabro

doi:10.1016/j.heliyon.2017.e00481

Upendra M Sainju, Andrew W Lenssen + Show 3 more

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https://doi.org/10.1016/j.heliyon.2017.e00481

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Abstract

Information on the long-term effect of management practices on soil C and N stocks is lacking. An experiment was conducted from 2004 to 2011 in the northern Great Plains, USA to examine the effects of tillage, crop rotation, and cultural practice on annualized crop residue (stems + leaves) returned to the soil and grain yield, and soil total C (STC) and total N (STN) stocks at the 0–120 cm depth. Tillage practices were no-tillage (NT) and conventional tillage (CT) and crop rotations were continuous spring wheat (Triticum aestivum L.) (CW), spring wheat-pea (Pisum sativum L.) (W-P), spring wheat-barley (Hordeum vulgaris L.) hay-pea (W-B-P), and spring wheat-barley hay-corn (Zea mays L.)-pea (W-B-C-P). Cultural practices were traditional (conventional seed rates and plant spacing, conventional planting date, broadcast N fertilization, and reduced stubble height) and improved (variable seed rates and plant spacing, delayed planting, banded N fertilization, and increased stubble height). Crop residue and grain yield were greater with CW and W-P than W-B-P and grain yield was greater with the traditional than the improved practice. The STC at 10–20 and 90–120 cm was greater with CW or W-P than other crop rotations in CT and greater with CW than W-B-P in NT. The STN at 20–40 cm was greater with W-P than CW and W-B-P in CT. With NT and the improved cultural practice, STN at 0–5, 5–10, 20–40, and 60–90 cm was greater with W-P and W-B-C-P than other crop rotations. The STN at 0–10 cm correlated with annualized crop residue and grain yield (r = 0.94–0.97, P ≤ 0.05). Increased crop residue returned to the soil increased soil C stock with CW and W-P and N stock with W-P, but removal of aboveground crop biomass for hay decreased stocks with W-B-P. Increased soil N stock had a beneficial effect on crop grain yield.

Highlights

It has been known that several decades of conventional tillage with crop-fallow system reduced crop yields and soil organic matter by 30 to 50% from their original levels due to mineralization of organic matter and reduction in the amount of crop residue returned to the soil under dryland cropping systems in the northern Great Plains, USA (Peterson et al, 1998; Aase and Pikul, 1995; Sainju et al, 2017)
Our objectives were to: (1) quantify the long-term effect of tillage, crop rotation, and cultural practice on annualized crop residue returned to the soil and grain yield from 2004 to 2011 under dryland cropping systems in the northern Great Plains, USA, (2) evaluate their effect on STC and STN at the 0–120 cm depth in 2011, and (3) relate STC and STN with annualized crop residue and grain yield
Crop rotation, and cultural practice had variable effect on annualized crop residue returned to the soil, grain yield, and STC and STN under dryland cropping systems in semiarid regions in the northern Great Plains, USA

Summary

Introduction

It has been known that several decades of conventional tillage with crop-fallow system reduced crop yields and soil organic matter by 30 to 50% from their original levels due to mineralization of organic matter and reduction in the amount of crop residue returned to the soil under dryland cropping systems in the northern Great Plains, USA (Peterson et al, 1998; Aase and Pikul, 1995; Sainju et al, 2017). Using improved management practices, such as no-tillage (NT), continuous cropping, and increased cropping intensity, decline in crop yields and soil organic matter can be reversed and become sustainable for the semiarid dryland cropping systems in this region (Halvorson et al, 2002; Sherrod et al, 2003; Sainju et al, 2017; Engel et al, 2017). Enhancing C and N stocks can improve soil structure and soil waternutrient-crop productivity relationships (Bauer and Black, 1994; Sainju et al, 2007, 2017) and mitigate emissions of greenhouse gases, such as CO2 and N2O, in the atmosphere (Paustian et al, 1997; Lal et al, 1999)

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