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LSP Report LS7018

Nitrogen Research on Corn Using
Conservation Tillage


 

Researcher: C.K. Stevenson, RCAT, Principal Researcher.

Proposal has been sent to OCPA, TFIO, PPIC and Pioneer Hi-Bred Ltd. OCPA and Pioneer have indicated that they are willing to fund the project for $4,000 per year each, for five years.

Funding: $16,000

Objectives

  1. To evaluate response to rates of N using conservation tillage.
  2. To compare three sources of N - urea, ammonium nitrate - urea (UAN) solution and anhydrous ammonia (AA) using conservation tillage.
  3. To compare various methods and times of incorporating UAN solution compared to urea worked in and AA knifed in application, using conservation tillage.
  4. To compare preplant and side-dress application of N using conservation tillage.
  5. To study the interaction effects of the above factors.

Expected Benefits

  1. To utilize conservation tillage practices in order to keep as much residue as possible on the soil surface to reduce soil erosion losses. This research will involve methods of applying nitrogen under conservation tillage, in order minimize volatilization losses..

Summary of Research Results

YIELD

Mulch-till gave a significantly higher yield than no-till at 5 of 10 site-years. It is not known why mulch-till gave a higher yield than no-till at these sites. The soil texture at all 3 sites is coarse (68% or > sand) therefore, one would expect that no-till would give as high yields as mulch-till.

There was large yield increases from N application at all but the Thamesville site in 1990 and 1991. At 6 of the 15 site-years there was a significant yield increase of 90 bu/a or greater. At 13 of the 15 site-years there was a significant yield increase of 55 bu/ac or greater. Disregarding the first 2 years at the Thamesville site, the rate of N that gave optimum yield was either 180 or 240 kg/ha of additional N (200 or 260 kg/ha of total N). The small yield increase from N application at Thamesville in 1990 and 1992 was probably due to residual N carryover from liquid swine manure applied in 1989.

There was a highly significant yield difference among N source, method and time of application treatments at 8 out of 10 site-years where mulch-till was compared to no-till. The AA and UAN solution soil injected treatments gave considerably higher yields than UAN solution and urea surface broadcast. The lower yields with urea and UAN solution surface broadcast applications are attributed to volatilization losses of N as ammonia (NHH3) when urea is hydrolyzed to ammonium (NH4+) shortly after application. Factors that may have contributed to volatilization losses of NH3 at these sites include - high (alkaline) soil pH, low soil CEC, warm temperatures, moist soil, good drying conditions (windy and low humidity) and the presence of considerable amounts of crop residue. With mulch-till, N losses from urea and UAN solution surface broadcast applications can be reduced by immediate incorporation with soil tillage. However, yields may still be slightly lower than AA and UAN solution soil injected. With no-till, urea and UAN solution should not be surface broadcast, but should be injected into the soil. It should be pointed out that while these results occurred at these 3 sites over the 5 years of the project, different results could occur under different conditions. For example on medium and fine textured soils with higher CEC's, and/or soil pH's that are acidic in reaction, and/or conventional tillage systems which leave less crop residues on the soil surface, volatilization losses from surface broadcast application of urea and UAN solution may be reduced and yields from surface applications may be equivalent to soil injected applications of AA and UAN solution.

N Content of Leaves

In general as the rate of N was increased the N content of ear leaves increased. The rate of N for optimum content of leaves varied depending on the site-year and results were similar to the grain yield results.

On the average, all the side-dress treatments and AA preplant had the highest and similar N content of ear leaves, while urea and UAN solution surface broadcast had the lowest N contents of leaves. Again the results were similar to those for grain yield.

Protein Content of Grain

In general as the rate of N was increased the protein content of grain was increased up to the highest rate of N used. The results were similar to the grain yield results.

On the average, all the side-dress treatments and AA preplant had the highest and similar protein contents of grain, while urea and UAN solution surface broadcast had the lowest protein contents of grain. Again, the results were similar to those for grain yield.

 

 

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Created: 03-23-1996
Last Revised: Tuesday, May 10, 2011 12:48:23 PM