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United States Department of Agriculture

Agricultural Research Service

Title: Yield Comparison and Economic Analysis of Conventional and Direct-Seed Cropping Systems at Pendleton

Authors
item Petrie, Steve - OREGON STATE UNIVERSITY
item Albrecht, Stephan
item Long, Daniel

Submitted to: Columbia Basin Agricultural Research Annual Report
Publication Type: Experiment Station
Publication Acceptance Date: May 1, 2006
Publication Date: June 1, 2006
Citation: Petrie, S., Albrecht, S.L., Long, D.S. 2006. Yield comparison and economic analysis of conventional and direct-seed cropping systems at Pendleton. Dryland Agricultural Research Annual Report. Oregon Agric. Exp. Sta. Special Report 1068.

Interpretive Summary: A winter wheat summer fallow rotation, using conventional tillage, is the principal dryland cropping system in the low (less than 12 inch) and intermediate rainfall (12-18 inch) areas of the Pacific Northwest (PNW). Conventional tillage, which includes plowing, will increase the conversion of soil organic matter to inorganic materials such as nitrogen, phosphorus, sulfur, and carbon dioxide. The release of these plant nutrients to the soil reduces the reliance on purchased fertilizer. However, loss of soil organic matter has adverse effects on soil physical, biological, and chemical properties. The continued decline in these soil properties has led to a concern if winter wheat-summer fallow system is agriculturally and economically sustainable. An experiment comparing conventional tillage-based summer fallow with a direct-seeded, summer fallow system with chemical weed control was conducted from 1997 through 2004 at the Pendleton Experiment Station. The objectives of this study are to evaluate the effects of tillage and N fertilization rates on winter wheat yields and economic returns. The winter wheat grain yield was greater in the conventional tillage system than in direct seeded system, although the differences are not statistically significant. Crop inputs costs and fallow costs have been roughly equal at equal nitrogen fertilization rates in the different tillage systems. The economically optimum nitrogen application rate was 80 pounds of nitrogen per acre in the established direct seeded plots and 120 pounds of nitrogen per acre in some newer direct seeded plots. Winter wheat yield was greatest and the partial net return was greatest at 120 pounds of fertilizer nitrogen per acre in the conventionally tilled plots. Including the available payments under the Conservation Security Program for the direct seeded treatments brought the partial net returns up to about the same as the conventionally tilled treatments.

Technical Abstract: The predominant dryland cropping system in the low (<12 inch) and intermediate rainfall (12-18 inch) areas of the Pacific Northwest (PNW) is winter wheat (Triticum aestivum L.)-summer fallow using conventional tillage. Tillage increases the rate of soil organic matter oxidation which releases plant nutrients such as nitrogen (N), phosphorus (P), and sulfur (S) reducing the reliance on purchased fertilizer inputs. However, loss of soil organic matter has adverse effects on soil physical, biological, and chemical properties. The long-term continued decline in these soil properties has led scientists to question if winter wheat-summer fallow system is sustainable. A field experiment comparing conventional tillage-based summer fallow with chemical summer fallow and direct-seeding was conducted from 1997 through 2004 at the Pendleton Experiment Station. The NTa direct-seed treatments were started in 1982 and a companion direct-seed trial (NTb) and conventional tillage (CT) treatments were started in 1997. The objectives of this research were to study the effects of tillage and N fertilization rates on winter wheat yields and economic returns. The winter wheat grain yield was greater in the CT than in either NTa or NTb, although the differences are not statistically significant. Crop inputs costs and fallow costs have been roughly equal at equal N application rates in the different tillage systems. The economically optimum N application rate was 80 lbs of N per acre in the NTa plots and 120 lbs of N per acre in the NTb plots. Winter wheat yield was greatest and the partial net return was greatest at 120 lbs of N per acre in the CT plots. Including the available payments under the Conservation Security Program for the NT treatments brought the partial net returns up to about the same as the CT treatments.

Last Modified: 12/20/2014
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