Stover accumulation has been shown to reduce corn grain yields in continuous corn production systems leading to suggestions that high corn prices, which result in more continuous corn production, will also could result in widespread implementation of stover removal practices.

However, effects of stover removal on soil fertility requirements and soil organic matter levels is an on-going concern and must be considered when growers decide to remove stover from continuous corn fields. In this project, Fred Below, Laura Gentry and associates assessed the effectiveness of stover removal for increasing corn yields in high-yielding and conventional environments as well as nutrient management consequences of stover removal.

High yielding environments consisted of higher plant populations, increased nutrient fertilizer application, insect protection traits, and application of fungicides.

Conventional environments consisted of more common planting populations, less intense fertilizer applications, no insect protection traits (a granular soil insecticide was applied at planting in both environments), and no fungicide application.

Additionally, three residue management treatments (crop rotation, partial stover removal, and tillage) were applied at two levels (9th-year continuous corn vs. long-term corn-soybean rotation, stover retained vs. 50% stover removed, and conventional-tillage vs. strip-tillage) to assess their individual and combined effects on the input treatments (plant population, nutrients, traits, and fungicide) and corn yields. In this summary we are reporting the results from 2013. Click table to view larger:

Yellow: Corn/Soybean rotation with all practices employed
Orange: Same, without P-K-S fertility added
Blue: Better hybrid taken out, standard hybrid selected

Strip-tillage is a relatively new reduced tillage system in the Central Corn Belt that protects soil from erosion, retains plant-available water, maintains soil structure and retains soil organic matter, and allows banding of fertilizers for more efficient plant uptake. Strip-tillage can substantially reduce soil compaction associated with multiple seedbed field operations; this also represents cost savings as a result of eliminating fuel use, labor, and equipment wear. These three agricultural management practices – crop rotation, residue management, and reduced tillage – were tested for their individual and cumulative effects on agricultural sustainability parameters and corn yields in combination with the omission treatment design previously employed to investigate high yield management factors for corn production.

(Above Executive Summary provided by Laura Gentry, PhD.)

Comments/Observations by Orthman Soil Science Agronomist, Michael Petersen:

As we observe and evaluate this data set that Gentry and Below studied several key points that come up before growers minds as they evaluate the validity of strip-tillage, rotational changes, hybrids, fertility programs even in a year like 2013 when the spring was wet and planting was delayed.

Please note in the supplied table the colored cells; yellow highlighted cells depict in the Corn-Soybean rotation portion of the Gentry-Below studies in the High Tech plots in which all practices are employed, incl: P-K-S etc fertilizer added precisely, high-sustainable N rates employed, best hybrids (with insect, herbicide resistant, day length, etc), higher seeding populations, and fungicides applied at premium time.

In orange cells the additional P-K-S etc fertility is subtracted.

In the blue cells the better hybrid selection is taken out and standard hybrid selected.

Much the same as what we have observed at the Orthman Research Farm near Lexington, Nebraska – precision tillage offers a slightly better yield advantage, which along with savings in fuel, time, and other costs – improves profit margins.

Lastly, in the last line of the table, precision tillage results in the averages Continuous Corn/Retained with Strip-Tillage compared to Conventional Tillage (second left column) an advantage leans to Strip-Till.