Nutrient Placement and Movement Under Zero-till Conditions

Illinois Fertilizer Conference Proceedings
January 24-26, 1994

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Nutrient Placement and Movement Under Zero-till Conditions

Lyle Paul¹

Introduction

As more grain producers change their operations to include reduced or no tillage, there is less opportunity for mixing nutrients into the soil. Some advocates of zero-till have said that the benefits of zero-till are increased if the soil is left undisturbed for a period of time (several years). They feel that this benefit is greater than any negative effect from the lack of fertilizer and soil mixing. There has been a concern by others that occasionally, fertilizer needs to be mixed into the soil to get maximum yields. This study attempts to answer the question of whether mixing of fertilizer and lime into the soil will benefit corn and soybean yields.

Materials and Methods

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_l to 50, K to 300, leave them untreated, or use maintenance applications of fertilizer. One-half of the plots were disked and plowed after liming and fertilization and one-half were untilled. In succeeding years all plots have been no-tilled.

These plots were established on Flanagan silt loam and Drummer silty clay loam. The average initial soil test levels are pH-5.6, Pi-39, and K-225. This field has been in a corn and soybean rotation with minimal fertilizer added.

Powdered limestone that would pass through a 200 mesh screen was applied to the individual plots according to the experimental plan and to the average of the four incremental soil tests of the individual plots. Fertilizer in the forms of 0-46-0 and 0-0-60 were also applied to the individual plots according to the plan and design. After fertilizer application in the spring of 1991 the plots selected for incorporated fertilizer were disked once and moldboard plowed. After plowing, the incorporated plots were disked twice and field cultivated once before planting. After planting the only additional disturbance to any plots was a row cultivation in 1991. The entire study area was row cultivated using a zero-till cultivator. Plant samples during the summer and grain samples at harvest were collected from all of the plots. All plots were machine harvested and yield measurements were taken.

Pioneer Hybrid 3417 was planted at 30,300 seeds per acre in 30 inch rows on May 21, 1993. Nitrogen was applied on June 24 at 180 lb N/acre as UAN (28% N) solution. It was injected at a depth of about 3" inches on thirty inch centers.

Soybean, DeKalb Genetics variety CX259 was planted with a John Deere no-till drill in seven inch rows at a seeding rate of 741b/acre on May 27, 1993. Herbicides were used for both crops and adequate weed control was achieved.

Results and Discussion

Yields in 1993 (Tables 1 and 2) responded to the fertilizer and lime applications. Given the low pH and fertility levels at the start of the study there was a benefit to the application of lime in the soybean crop and to the application of fertilizer in both crops. In corn with surface application of lime and fertilizer, increasing levels of fertilizer showed stronger results immediately. The incorporation of fertilizer and lime seems to have a larger relative effect on soybean yields than on corn yields. With the somewhat disappointing yield levels this year, the effect of fertilizer and lime was less pronounced this year than in previous years.

Additional study will be necessary to determine if the original placement and amounts of fertilizer and lime will make greater differences in the results over time.