Wheat Response to Fertilizer Nitrogen in No-till and Conventional-till Dual-purpose Wheat Production Systems

Conservation of our region’s natural resources is extremely important at the highest levels of government.   Conserving those resources is essential to long-term viability of rural economies.  Crop residue on the soil surface is beneficial in terms of, reduced soil erosion, rainfall capture, rainfall retention and seedling protection.  Producers in this area have not adopted no-till in a grazing system because of reservations about stand establishment, soil compaction, soil fertility, lack of proper equipment, and weed control.  Understandably, most do not want to risk their future on an unproven technology.  However, a few producers have successfully implemented no-till management in grain-only systems.

The Texas Rolling Plains has very large and diverse wheat/stocker operations which rural economies depend on as a major source of revenue.  In these systems, wheat is planted in September under conventional tillage.  Numerous field operations with large, expensive equipment along with high operating and labor costs are required to prepare Aclean@ fields prior to seeding.  Soil moisture is lost in the process.  Soil erosion by wind and water can be significant on exposed soil.  Wheat seedlings are unprotected from desiccating wind and washing out.  Large areas are subject to replanting, creating costly delays in wheat establishment and plant growth needed in graze and grain wheat/stocker systems.  Conservation tillage holds promise in mitigating soil and moisture losses as well as revenue in wheat/stocker systems through increased soil organic matter, enhanced capture and retention of limited precipitation and decreased risk of reseeding.

Fertilizer requirements in conservation tillage systems for wheat and stocker cattle production in the Rolling Plains are unknown.  A high research priority has been placed on no-till systems in a dual-purpose wheat/stocker enterprise, particularly development of efficient nitrogen and phosphorus fertility programs.  A key input to all wheat production is nitrogen fertilizer.  Information on nitrogen fertility response of wheat in a no-till grazing system does not exist, although this knowledge is vital to successful implementation of no-till grazing systems.

Our current research indicates that stand establishment in no-till systems can be successful with the proper equipment.  Furthermore, soil compaction may not be as serious as previously believed, as long as a reasonable amount of residue is maintained on the soil surface.

The primary objective of this research is to identify nitrogen fertility levels that maximize forage and beef yields as well as grain yields in no-till and conventional-till wheat/stocker production systems.  A secondary objective is to quantify the effects of nitrogen fertility management on plant soluble proteins and bloat potential.  Furthermore, preliminary research will be conducted to determine the effects of high nitrogen fertilization on the bloat and gain response of cattle.

Benefits and expected outcome of this no-till wheat research:

  1. Develop guidelines on nitrogen fertility requirements for successful no-till and conventional-till wheat-grazing systems.
  2. Determine the degree to which rainfall is captured and retained using soil moisture sensors.
  3. Monitor seasonal, as well as yearly, soil compaction profiles in a grazed environment.
  4. Determine grain quality of wheat from grazed plots receiving various nitrogen treatments.
  5. Determine the economics of a no-till wheat/stocker system as it relates to forage production and grain yield and compare with a conventional-till system
  6. Quantify the responses of soluble proteins in wheat forage to increasing levels of nitrogen fertility as an index of bloat potential.
  7. Characterize the potential impact of nitrogen fertility induced bloat on cattle production.
  8. Disseminate research results to wheat producers through appropriate publications, seminars, workshops, and/or field days.

Benefits of no-till wheat production may not be fully realized in one season.  Therefore, this research is planned for a three-year period.  The site will be located about 10 miles south of the Vernon Research Center on the Smith/Walker research unit.  The plot study will be conducted on a 35-acre pasture with free-ranging stocker cattle (400 to 500 weights).  Planting date will be mid-September with a cultivar to be determined.  Fertility plots will be 20 to 40 ft wide by 200 ft long.  All plots will received an initial application of 40 lb/ac P2O5.  Nitrogen fertility levels will be 0, 30, 60, 90, and 120 lbs N/ac applied at planting.  In late January, half of the plot will be top-dressed with an additional 45 lbs N/ac and the other half will receive no additional N.   All treatments will be established on no-till and conventional-till areas using liquid fertilizer materials.  Small exclosures (cages) will be used in determining seasonal forage production.  Soil moisture blocks will be established 18 inches deep in the soil to measure seasonal moisture.  Soil penetrometer readings will be taken periodically throughout the year to determine soil compaction profiles.  Plant samples for soluble proteins will be taken at 14-d intervals.  At first hollow stem, 8-ft by 16-ft cages will be established on all plots for grain yield determination.  Harvested grain will be sent to College Station for protein analysis and baking quality characteristics.

The potential impact of nitrogen fertility to induce bloat in stocker cattle will be determined in a pasture study by measuring the timing, duration and severity of bloat in stocker cattle from a common origin over a 2-to 3-year period.  Each year 70 to 80 head of individually identified cross-bred steers or heifers will be grazed season-long on two 37-acre pastures: one fertilized at 120 lbs of N/acre and the other fertilized at 60 lbs of N/acre.  Each pasture will receive the same N level each year.  Cattle will be weighed at 28-d intervals. Forage soluble protein and fiber composition will be determined at 14-d intervals.  Cattle will be individually scored for bloat condition at 14-d intervals for 2 to 3 consecutive days.  Bloat scores will be correlated to monthly and season-long weight gain.  Economic impact of bloat on individual animal value will be determined

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