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United States Department of Agriculture

Agricultural Research Service

Research Project: ECOLOGICALLY-SOUND PEST, WATER AND SOIL MANAGEMENT STRATEGIES FOR NORTHERN GREAT PLAINS CROPPING SYSTEMS

Location: Agricultural Systems Research Unit

Title: Irrigation system and tillage effects on soil carbon and nitrogen fractions

Authors
item Sainju, Upendra
item Stevens, William
item Evans, Robert
item Iversen, William

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 2, 2013
Publication Date: July 25, 2013
Repository URL: http://handle.nal.usda.gov/10113/57101
Citation: Sainju, U.M., Stevens, W.B., Evans, R.G., Iversen, W.M. 2013. Irrigation system and tillage effects on soil carbon and nitrogen fractions. Soil Science Society of America Journal. 77(4): 1225-1234.

Interpretive Summary: Conventional tillage used for growing sugarbeet and malt barley in the irrigated cropping systems in the lower Yellowstone valley in eastern Montana and western North Dakota can increase soil erosion damage sugarbeet seedling from windblown soil and reduce soil quality due to organic matter mineralization. Similarly irrigation water applied either in furrow or through mid-elevation spray application (MESA) can increase surface runoff and leaching due to excessive water flow and loss of water soluble C and N in the soil. Therefore, conservation tillage and improved irrigation system are needed to increase water-use efficiency and soil quality and reduce soil erosion. A study was conducted to evaluate the effect of two irrigation systems (MESA and low energy precision application [LEPA]) and two crop rotations (conventional-tilled sugarbeet/conventional-tilled malt barley [CTS-B] and strip-tilled sugarbeet/minimum-tilled malt barley [STS-B]) on crop biomass (stems + leaves) yield, surface residue, and soil C and N fractions at the 0- to 20-cm depth. Soil C and N fractions were total C and N (STC and STN), particulate organic C and N (POC and PON), microbial biomass C and N (MBC and MBN), potential C and N mineralization (PCM and PNM), NH4-N, and NO3-N. The experiment was conducted from 2004 to 2007 in a Savage clay loam in Sidney, MT. While crop biomass increased from 2004 to 2007, surface residue was greater with STS-B than with CTS-B from 2005 to 2007. The STC and PCM at 10 to 20 cm were greater with CTS-B than with STS-B but STN at 0 to 5 cm was greater with STS-B than with CTS-B in LEPA. Soil NH4-N content at 0 to 20 cm was greater with STS-B than with CTS-B in 2005 but NO3-N content was lower with STS-B than with CTS-B in most years. The POC at 5 to 10 cm and PNM at 0 to 5 cm were greater with CTS-B than with STS-B but MBC at 0 to 5 cm was greater with STS-B than with CTS-B. The MBN at 10 to 20 cm was greater in LEPA than in MESA and at 5 to 10 cm was greater with CTS-B than with STS-B. While reduced tillage increased surface residue with STS-B, crop residue incorporation to a greater depth, followed by water application near the soil surface may have increased subsoil C storage, microbial activity, and N mineralization with CTS-B in the LEPA system. Increased N loss due to leaching, volatilization, and denitrification probably reduced soil NO3-N content with STS-B than with CTS-B. Adopting strip tillage every year instead of only in alternate years of the cropping system, along with the LEPA irrigation system may increase surface residue, C and N storage, and soil quality and productivity in the long run compared to conventional tillage with MESA. Such a system will also reduce soil erosion and sugarbeet seeding damage due to windblown soil and use water more efficiently for sustaining crop yield and quality.

Technical Abstract: Irrigation system and crop rotation may affect soil C and N fractions by influencing crop biomass yield and movement of water soluble C and N in the soil. We studied the effect of two irrigation systems (mid-elevation spray application [MESA] and low energy precision application [LEPA]) and two crop rotations (conventional-tilled sugarbeet (Beta vulgaris L.)/conventional-tilled malt barley (Hordeum vulgare L.) [CTS-B] and strip-tilled sugarbeet/minimum-tilled malt barley [STS-B]) on crop biomass (stems + leaves) yield, surface residue, and soil C and N fractions at the 0- to 20-cm depth. Soil C and N fractions were total C and N (STC and STN), particulate organic C and N (POC and PON), microbial biomass C and N (MBC and MBN), potential C and N mineralization (PCM and PNM), NH4-N, and NO3-N. The experiment was conducted from 2004 to 2007 in a Savage clay loam in Sidney, MT. While crop biomass increased from 2004 to 2007, surface residue was greater with STS-B than with CTS-B from 2005 to 2007. The STC and PCM at 10 to 20 cm were greater with CTS-B than with STS-B but STN at 0 to 5 cm was greater with STS-B than with CTS-B in LEPA. Soil NH4-N content at 0 to 20 cm was greater with STS-B than with CTS-B in 2005 but NO3-N content was lower with STS-B than with CTS-B in most years. The POC at 5 to 10 cm and PNM at 0 to 5 cm were greater with CTS-B than with STS-B but MBC at 0 to 5 cm was greater with STS-B than with CTS-B. The MBN at 10 to 20 cm was greater in LEPA than in MESA and at 5 to 10 cm was greater with CTS-B than with STS-B. While reduced tillage increased surface residue with STS-B, crop residue incorporation to a greater depth, followed by water application near the soil surface may have increased subsoil C storage, microbial activity, and N mineralization with CTS-B in the LEPA system. Increased N loss due to leaching, volatilization, and denitrification probably reduced soil NO3-N content with STS-B than with CTS-B.

Last Modified: 4/20/2014
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