Page 2 - January Newsletter

Crop Production By: Jeanne Falk JonesResearch on Tillage Intensity in a Long-Term Wheat-Sorghum-Fallow RotationThis is a research report from a long-term research project at the K-State Southwest Research-Extension Center at Trib- une. Authors of the research report are L.A. Haag, A. Bur- nett, D. Bond, J. Slattery, and A. Schlegel. You can see this research report and others from K-State at www.newprairiepress.org and search for this title or there is a direct link on the K-State Sunflower District Agronomy website at www.sunflower.ksu.edu/agronomy.Summary.This study was initiated in 1991 at the K-State Southwest Research-Extension Center near Tribune, KS. The purpose of the study was to identify the effects of tillage intensity on precipitation capture, soil water storage, and grain yield in a wheat-sorghum-fallow rotation. Grain yields of wheat and grain sorghum increased with decreased till- age intensity in a wheat-sorghum-fallow (W-S-F) rotation. In 2022, available soil water at sorghum planting was greater for no-tillage (NT) than reduced tillage (RT), which was greater than conventional tillage (CT). For wheat there was a similar pattern as sorghum, with availa- ble soil water at wheat planting being in the order of NT>RT>CT. Averaged across the most recent 22 years of the study, available soil water at wheat planting was 0.60 inch greater for NT than RT and approximately 1.7 inches greater than CT. Average available soil water at sorghum planting was greater in the order RT=NT>CT averaging 7.9 inches for RT and NT and 5.9 inches for CT. Averaged across the past 22 years, NT wheat yields were 6 bu/a greater than RT and 10 bu/a greater than CT. Averaged across the past 22 years, sorghum yields with longterm NT have been 57% greater than with RT (82 vs. 52 bu/a).Experimental Procedures.Research on different tillage intensities in a W-S-F rotation at the Tribune, KS, unit of the Southwest Research- Extension Center was initiated in 1991. The three tillage intensities in this study are conventional (CT), reduced (RT), and no-tillage (NT). The CT system was tilled as needed to control weed growth during the fallow period. On average, this resulted in 4 to 5 tillage operations per year, usually with a blade plow or field cultivator. The RT system originally used a combination of herbicides (1 to 2 spray operations) and tillage (2 to 3 tillage operations) to control weed growth during the fallow period; however, in 2001, the RT system was changed to using NT from wheat harvest through sorghum planting (short-term NT) and CT from sorghum harvest through wheat planting. The NT system exclusively used herbicides to controlweed growth during the fallow period. All tillage systems used herbicides for in-crop weed control.Results and Discussion.Soil Water. The amount of available water in the soil pro- file (0–8 ft) at wheat planting varied greatly from year to year. In 2022, available soil water at wheat planting was greater with NT (15.3 inches) than RT (12.5 inches) and CT (13.9 inches). Across the 22-yr study, available soil water at wheat planting was greatest for NT (8.44 inches) fol- lowed by RT (7.85 inches), and CT (6.72 inches). Similar to wheat, the amount of available water in the soil profile at sorghum planting varied greatly from year to year. In 2022, available soil water at sorghum planting was greater with NT (7.8 inches) than RT (5.7 inches) and least with CT (5.3 inches). On average, available soil water at sorghum planting was similar for NT and RT and about 2 inches greater than CT.Grain Yields. Wheat yields in 2022 were significantly re- duced by hail damage and are not reported. Since 2001, wheat yields have been depressed in 12 of 22 years, pri- marily because of lack of precipitation, winterkill (2015), viral disease (2017), and hail (2022). Reduced tillage and NT increased wheat yields. On average, wheat yields were 10 bu/a higher for NT (33 bu/a) than CT (23 bu/a). Wheat yields for RT were 4 bu/a greater than CT even though both systems had tillage prior to wheat. Yields of NT were significantly less than CT in only one year (2008) and RT in 2 of the 22 years (2001, 2008). Grain sorghum yields in 2022 were slightly above the long-term average. Sorghum yields were 60% greater with NT than RT (108 vs. 67 bu/a) while CT yields were the least (52 bu/a). The yield benefit from reducing or eliminating tillage was greater for grain sorghum than wheat. Grain sorghum yields for RT aver- aged 20 bu/a more than CT, whereas NT averaged 30 bu/a more than RT. For sorghum, both RT and NT used herbi- cides for weed control in the wheat stubble post-harvest, and in both the RT and NT systems, the sorghum was “no- till” planted into wheat stubble. Using tillage in the sum- mer-fallow period ahead of seeding wheat, while only re- ducing wheat yields in a minor way, subsequent sorghum yields were being significantly reduced. This yield benefit with long-term vs. short-term NT (RT) has been observed in most years since the RT system was changed in 2001. Averaged across the past 20 years, sorghum yields with long-term NT have been 57% greater than with RT (82 vs. 52 bu/a).K-State Research and Extension is an equal opportunity provider and employer.