Illinois Fertilizer
Conference Proceedings
January 28-30, 1991
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Lyle Paul1
Tillage mixes fertilizer into the soil. Whether tillage is necessary in a zero-till system for fertility mixing has been discussed. Stratification of nutrients has occurred in some studies without tillage, but whether this is detrimental to crop yields needs to be determined.
As producers change to more limited tillage, there is less opportunity to mix nutrients into the soil. Some advocates of zero-till have said that the benefits of zero-till are better if the soil is left undisturbed for a period of time (several years). There has been a concern on the part of many that occasionally the applied fertilizer needs to be mixed into the soil to get maximum yields. This study attempts to answer the question if mixing of fertilizer into the soil will benefit corn and soybean yields.
This study is a randomized complete block design with four replications with corn and soybeans being planted each year in a corn-soybean rotation. The initial treatments were to raise the pH to 6.5, P, to 50, K to 300, and leave them untreated, or use maintenance applications of fertilizer. One-half of the plots would then be incorporated and one-half left on the. surface. Thereafter, all plots will receive crop-removal fertilizer additions. The plots that had the fertilizer worked in originally will have the maintenance levels. incorporated, and the plots with surface-applied nutrients will continue to receive surface-applied nutrients. The corn and soybeans on all plots will be planted zero-till with appropriate herbicides used.
These plots were established on Flanagan silt loam and Drummer silty clay loam. The average initial soil test levels are pH-5.6, P1-38.7, and K-225.6. This field has been in a corn and soybean rotation with minimal fertilizer added. The only tillage that is planned after the initial working in of lime, P and K will be the shallow incorporation of the fertilizer on the plots that received the incorporated fertilizer in the first application. Fertilizer will be hand-spread on surface plots and shallowly-injected on incorporated plots. Nitrogen on the corn that will be shallowly injected, will be 28 percent on all plots.
Annual pH, P and K tests will be made in incremental depths of 0-1.5", 1.5"-3", 3-6" and 6-12" on all plots. Plant leaf samples, grain moisture and yields will be taken on all plots each year.
The plots are just being established and there are no yield results' due to different fertilizer treatments available at this time.
