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United States Department of Agriculture

Agricultural Research Service

Title: Crop Management Effects on Productivity, Soil Nitrogen, and Soil Carbon

Authors
item Halvorson, Ardell
item Reule, Curtis
item Poole, Jim - POOLE FARMS, TEXLINE, TX
item Follett, Ronald

Submitted to: Fluid Fertilizer Foundation Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: January 15, 2003
Publication Date: February 16, 2003
Citation: Halvorson, A.D., Reule, C.A., Poole, J., Follett, R.F. 2003. Crop management effects on productivity, soil nitrogen, and soil carbon. Fluid Fertilizer Foundation Symposium Proceedings. Scottsdale, AZ. 20:102-113.

Interpretive Summary: The influence of soil fertility on soil organic carbon (SOC) sequestration and nitrate-nitrogen (NO3-N) leaching potential was evaluated under irrigated continuous corn production in northwest Texas. Research has indicated that a soil fertility program that maximizes crop yields may also positively affect SOC levels. Two fertility levels were established on separate halves of pivot irrigation systems located near Dalhart and Texline, Texas. The Dalhart site was on a Dallam fine sandy loam soil and the Texline site on Conlen and Dumas clay loam soils. The normal fertility program (N1) has a corn yield goal of 250+ bu/a. The higher fertility treatment (N2) received the same fertilizer rates as the N1 treatment plus an additional application of liquid N and P fertilizer to the corn residue just prior to fall tillage to aid in the decomposition of corn residues. Soil was collected from the cropped and adjacent native sod areas to evaluate changes in SOC as a result of conversion from native grass to irrigated corn 7 years ago. Results indicate that the SOC levels in the cropped area are increasing with each corn crop at both sites. In 2001at the Dalhart site, SOC levels in the cropped area exceeded the native sod SOC levels after 7 years of continuous corn. At the Texline site, SOC in the cropped area exceeds that of the native sod after 6 corn crops. Root zone soil NO3-N levels have increased in the cropped area compared to native grass at both sites and have increased more with the N2 management treatment than with N1. Effects of soil fertility level on SOC sequestration was not assessed in this report since insufficient time has lapsed since study initiation to accurately detect changes in SOC. Several more cropping seasons will be needed to monitor changes caused by fertility management level.

Technical Abstract: We evaluated the influence of soil fertility on soil organic carbon (SOC) sequestration and nitrate-nitrogen (NO3-N) leaching potential under irrigated continuous corn production in northwest Texas. Research has indicated that a fertility program that maximizes crop yields will also have positive effects on SOC levels. Two fertility levels were established on separate halves of pivot irrigation systems located near Dalhart and Texline, Texas. The Dalhart site was on a Dallam fine sandy loam soil and the Texline site on Conlen and Dumas clay loam soils. The normal fertility program (N1) had a corn yield goal of 250+ bu/a. The higher fertility treatment (N2) received the same fertilizer rates as the N1 treatment plus an additional application of liquid N and P fertilizer to the corn residue just prior to fall tillage to aid in the decomposition of corn residues. Soil was collected from the cropped and adjacent native sod areas to evaluate changes in SOC as a result of recent conversion (7 years) from native grass to irrigated corn. The SOC levels appear to be increasing with each additional corn crop at both sites. In 2001, the SOC level in the cropped area appears to have exceeded the SOC levels of the native sod at Dalhart after 7 corn crops. At the Texline site, SOC in the cropped area exceed the native sod SOC levels after 6 corn crops. Root zone soil NO3-N levels have increased in the cropped area compared to native grass at both sites and have increased more with the N2 management treatment than with N1. We were not able to assess the effects of fertility level on SOC sequestration in this report since insufficient time has lapsed since study initiation to accurately detect significant differences in SOC. Several more cropping seasons will be needed to monitor changes caused by fertility management level.

Last Modified: 9/2/2014
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