ARS | Publication request: Dryland residue and soil orgranic matter as influenced by tillage, crop rotation, and cultural practice

Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 18, 2010
Publication Date: December 15, 2010
Repository URL: http://hdl.handle.net/10113/50219
Citation: Sainju, U.M., Lenssen, A.W., Caesar, T., Jabro, J.D., Lartey, R.T., Evans, R.G., Allen, B.L. 2011. Dryland residue and soil orgranic matter as influenced by tillage, crop rotation, and cultural practice. Plant and Soil Journal. 338:27-41.

Interpretive Summary: In the northern Great Plains, USA, traditional farming systems, such as conventional tillage with wheat-fallow, have decreased soil organic matter by 30 to 50% from the original levels. Intensive tillage increases the oxidation of soil organic matter and fallowing increases its loss by reducing the amount of plant residue returned to the soil and by increasing mineralization due to increased soil water and temperature. As a result, the traditional farming system has become unsustainable and uneconomical. Therefore, novel management practices are needed to increase dryland soil organic matter and crop yields. The effects of tillage, crop rotation, and cultural practice were evaluated on dryland crop biomass (stems + leaves) yield, surface residue, and soil organic C (SOC) and total N (STN) at the 0-20 cm depth in Williams loam from 2004 to 2007 in eastern Montana, USA. Treatments were two tillage practices [no-tillage (NT) and conventional tillage (CT)], four crop rotations [continuous spring wheat (CW), spring wheat-pea (W-P), spring wheat-barley hay-pea (W-B-P), and spring wheat-barley hay-corn -pea (W-B-C-P)], and two cultural practices [regular (conventional seed rates and plant spacing, conventional planting date, broadcast N fertilization, and reduced stubble height) and ecological (variable seed rates and plant spacing, delayed planting, banded N fertilization, and increased stubble height)]. Crop biomass and N content were greater in W-B-C-P than in CW in 2004 and 2005 and greater in ecological than in regular cultural practice in CT. Soil surface residue amount and C and N contents were greater in NT than in CT, greater in CW, W-P, and W-B-C-P than in W-B-P, and greater in 2006 and 2007 than in 2004 and 2005. The SOC and STN concentrations at 0-5 cm were greater in CW than in W-P or W-B-P in NT and CT from 2005 and 2007. At 0-20 cm, SOC content was greater in CW than in W-P in NT but STN was greater in W-P than in CW in CT. Both SOC and STN increased from 2004 to 2007. Diversified crop rotation and delayed planting with higher seed rates and banded N fertilization increased the amount of crop biomass returned to the soil and surface residue C and N. Although no-tillage increased surface residue C and N, continuous nonlegume cropping increased soil C storage but legume-nonlegume crop rotation increased N storage compared with other rotations. Continued return of crop residue from 2004 to 2007 increased soil C and N storage.

Technical Abstract: Novel management practices are needed to increase dryland soil organic matter and crop yields that have been declining due to long-term conventional tillage with spring wheat (Triticum aestivum L.)-fallow system in the northern Great Plains, USA. The effects of tillage, crop rotation, and cultural practice were evaluated on dryland crop biomass (stems + leaves) yield, surface residue, and soil organic C (SOC) and total N (STN) at the 0-20 cm depth in Williams loam (fine-loamy, mixed, superactive, frigid, Typic Argiustolls) from 2004 to 2007 in eastern Montana, USA. Treatments were two tillage practices [no-tillage (NT) and conventional tillage (CT)], four crop rotations [continuous spring wheat (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)], and two cultural practices [regular (conventional seed rates and plant spacing, conventional planting date, broadcast N fertilization, and reduced stubble height) and ecological (variable seed rates and plant spacing, delayed planting, banded N fertilization, and increased stubble height)]. Crop biomass and N content were greater in W-B-C-P than in CW in 2004 and 2005 and greater in ecological than in regular cultural practice in CT. Soil surface residue amount and C and N contents were greater in NT than in CT, greater in CW, W-P, and W-B-C-P than in W-B-P, and greater in 2006 and 2007 than in 2004 and 2005. The SOC and STN concentrations at 0-5 cm were greater in CW than in W-P or W-B-P in NT and CT from 2005 and 2007. At 0-20 cm, SOC content was greater in CW than in W-P in NT but STN was greater in W-P than in CW in CT. Both SOC and STN increased from 2004 to 2007. Diversified crop rotation and delayed planting with higher seed rates and banded N fertilization increased the amount of crop biomass returned to the soil and surface residue C and N. Although no-tillage increased surface residue C and N, continuous nonlegume cropping increased soil C storage but legume-nonlegume crop rotation increased N storage compared with other rotations. Continued return of crop residue from 2004 to 2007 increased soil C and N storage.