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United States Department of Agriculture

Agricultural Research Service

Title: Managing Soil Fertility in Diverse Dryland Cropping Systems

Authors
item Westfall, Dwayne - COLORADO STATE UNIVERSITY
item Vigil, Merle
item Peterson, Gary - COLORADO STATE UNIVERSITY

Submitted to: Proceedings from Dynamic Cropping Systems: Prinicples, Processes, and Challenges
Publication Type: Proceedings
Publication Acceptance Date: July 1, 2003
Publication Date: August 4, 2003
Citation: WESTFALL, D.G., VIGIL, M.F., PETERSON, G.A. MANAGING SOIL FERTILITY IN DIVERSE DRYLAND CROPPING SYSTEMS. Proceedings from Dynamic Cropping Systems: Prinicples, Processes, and Challenges. 2003. p. 29-36. Aug. 4-7, 2003, Bismarck, ND.

Interpretive Summary: Management of fertilizer in intensive no-till dryland cropping systems is different than in conventional wheat summer fallow (WF). In these systems, an increase in biomass production and changes in nutrient cycling occurs that affects optimal fertilizer management. The objective of this paper is to summarize the latest findings on this subject. Here we report that for these systems that fertilizer N rate is more critical than placement and/or source; the N requirement of intensive cropping systems is about 73% greater than WF and the probability of nitrate leaching is less. If intensive systems are fertilized properly, wheat yields equal those obtained in WF. Sunflower generally respond to up to 30 lb N/A, and rarely to 60 lb N/A. However, there is also a small decrease in oil content of sunflower with increased N rates. Phosphorus requirements of intensive systems are similar to stubble-mulch managed systems. If wheat is fertilized properly in a wheat-corn-fallow (WCF) system, there will be adequate P carryover to satisfy the corn crop's requirement. We have not observed significant corn grain yield responses to P in WCF systems.

Technical Abstract: Management of fertilizer in intensive no-till dryland cropping systems is important to their economic and environmental sustainability. In the past, much work has been done on the fertilizer requirements of traditional stubble-mulch tillage wheat-fallow (WF). However, with the increase in biomass production and change in nutrient cycling that occurs in intensive no-till cropping systems, we must take a second look at current fertilizer management strategies. The objective of this paper is to summarize the latest findings on this subject. It has been reported that fertilizer N rate is more critical than placement and/or source. The N requirement of intensive cropping systems is about 73% greater than WF. However, due to the increased N use efficiency and greater water use of these intensive systems, the probability of nitrate leaching is less. If intensive systems are fertilizer properly, wheat yields will equal those obtained in WF. Sunflower generally respond to up to 30 lb N/A, and rarely to 60 lb N/A. However, there is also a small decrease in oil content of sunflower with increased N rates. Phosphorus requirements of intensive systems are similar to stubble-mulch managed systems. If wheat is fertilized properly in a wheat-corn-fallow (WCF) system, there will be adequate P carryover to satisfy the corn crop's requirement. We have not observed significant corn grain yield responses to P in WCF systems. Soil testing coupled with previous experience are critical factors in development of economically and environmentally sound fertilizer management practices.

Last Modified: 8/21/2014
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