Tillage and Cropping Systems to Increase Dryland Crop Production in Southwest Oklahoma by Gary Strickland Extension Educator – OCES Jackson County

Team Approach OSU’s IPM Program Area Extension Staff – Mr. Jerry Goodson (SWREC), Dr. Mark Gregory, Mr. Rick Kochenower, Mr. Terry Pitts, and Daniel Skipper State Extension Staff – Dr. J.C. Banks, Mr. Shane Osborn, Dr. Jeff Edwards, Dr. Chad Godsey, Dr. Randy Taylor OAES – Mr. Rocky Thacker and SWREC Crew, Jackson County OCES Program Local and Private Industry Sponsors (i.e.; Oklahoma Grain Sorghum Producers, Seed Companies, Coops, etc…)

Objectives of the Study Determine the impact of different cropping systems on resident insect populations Determine the effect of tillage and cropping management systems on weed species population dynamics Determine and demonstrate the effects of tillage and crop rotation on the economic components of weed, insect, and yield management in cotton, wheat, and grain sorghum production systems in Southwest Oklahoma To estimate the effects of tillage and cropping systems on SOM accumulation

Study Design Randomized Complete Block with a Split Plot Design Two Tillage Systems Three Crops (Cotton, Wheat, Grain Sorghum) Seven Cropping Systems (C-W-GS, C-W, C-GS, W-DCGS-C, W, C, GS)

Summary of Insect Data To date, no significant differences have been noted between tillage treatments or among cropping systems regarding insect populations or species. Crop scouting principle has been reinforced in this study When a buildup of insect pests occurs a corresponding buildup of beneficial insects has occurred

Pest and Beneficial Insect Relationship

Soil Organic Matter Management - Importance in Dryland Crop Production Soil Erosion Prevention Increased Soil Water Storage Capacity Increased Water Infiltration Rates Decreased Soil Evaporation Rates Increase of In-Season Precipitation Use Efficiency Increased Organic Matter Pool Increased Cation Exchange Complex (CEC) Increased Anion Exchange Complex (AEC) Decrease in Soil Compaction in the Long Term

Tillage by Crop Rotation System SOM Comparisons (2002-2008). TS C-W-GS C-W C-GS W-DCGS-C C W GS Mean L.S.D. (.05) NT 2.00(2) 1.49(6) 1.93(2) 1.63(6) 2.03(2) 1.84(6) 2.08(2) 1.71(6) 2.13(2) 1.94(2) 1.68(6) 2.42(2) 1.79(6) 1.69(6) NS(2) NS(6) CT 1.76(2) 1.64(6) 1.87(2) 1.83(6) 1.82(2) 1.70(6) 1.84(2) 1.72(6) 1.79(2) 1.96(2) 1.87(6) 2.06(6) 1.73(6) 0.13(6)(.10) (2) 2 inch sampling depth; (6) 6 inch sampling depth

Organic Matter Summary The interaction between tillage systems and cropping systems was significant at the .05 probability level therefore comparisons should be primarily between cropping systems within a tillage system. Soil organic matter accumulation, in general, indicate no significant differences between cropping systems within tillage treatments to date with the exception of the 6 inch sampling depth in the CT cropping systems. But the data does reflect a trend across cropping systems of increasing organic matter content in the top two inches when compared to the six inch depth in both systems, NT systems are 38% higher and the CT systems are 16% higher. However, a significant difference between the two systems does exist (as indicated by the significant interaction) with the NT systems showing higher levels of SOM across all cropping systems, except for the W only system, at the 2 inch layer.

Summary of Weed Data Only a few significant differences have been noted to date between tillage treatments or among cropping systems In general the NT systems show higher weed populations than the CT systems Common weed species that continue to be present in the field include: common purslane, prickly lettuce, winter grasses (bromegrass species primarily), marestail, and henbit New weed species that have appeared with time include: honeyvine milkweed, morningglory, red stem filaree, and common groundsel. To date current herbicide programs seem to be working in terms of weed population control with the exception of the Grain Sorghum No-Till Mono-Crop where significant increase in pigweed species occurred and has remained after a glyphosate and two atrazine herbicide applications; and common groundsel in the cotton systems.

2006 Cotton Weed Populations Treatments Common Purslane Prickly Lettuce Pigweed C-W (NT) 1.0ψ (P.E.) 0.0 (P.H.) 0.5 (P.E.) 0.5 (P.H.) C (NT) 4.3 (P.E.) 0.3 (P.E.) 4.0 (P.E.) C-W (CT) 0.0 (P.E.) 0.7 (P.E.) C (CT) Ψ: Weed numbers are from counts taken in 1/1000 of an acre.

Post-E Pigweed Counts in 2008 Grain Sorghum Systems Tillage System C-GS GS Mean L.S.D. (.05) NT 5.8ψ 57.2 31.5 24.2 CT 0.33 0.5 0.42 NS Ψ: Numbers are counts taken in 1/1000 of an acre

Crop Herbicide Systems Time of Applica- tion Mode of Action Group Crop Use Crop Rotation Intervals (M) Broadleaf Tank Mixes Grazing Restric-tion (Days) Roundup (Glyphosate) Pre, Post, HA Inhibition of EPSP Syn. (9) C, W, GS All Crops – 0M Yes 0 Days Dual (metolachlor) Pre & Post Shoot Inhibitors (15) GS, C W-4.5M; C & GS – Next Spring Do not feed Maverick (sulfosulfuron) Post ALS Inhibitor (2) W C &GS – 12M Osprey (mesosulfuron-methyl) C – 3M; GS- 10M Olympus Flex C & GS – 12M Finesse Grass & Broadleaf ALS Inhibitor (2) C & GS - Bioassay 7 Days Axial XL ACCase Inhibitor (1) C & GS – 4M 30 Days

Crop Herbicide Systems Continued Time of Applica-tion Mode of Action Group Crop Use Crop Rotation Intervals (M) Broadleaf Tank Mixes Grazing Restric-tion Power Flex Post ALS Inhibitor (2) W C & GS – 9M Yes 7 Days MCPA Synthetic Auxin (4) After Harvest Harmony Extra C & GS – 1.5M NA Peak (prosulf-uron) W & GS W – 0M GS – 1M C – 18M 30 Days Basagran (bentazon) PS II Inhibitor (6) GS W-0M C – 0M Buctril (bromoxy-nil) W – 1M C – 1M 45 Days Atrazine PS II Inhibitor (5) See Label 21 Days

Crop Yield and Economic Responses

Production Economic Summary for 2003-2009 While not always significant, the NT crop systems have shown a consistent trend for higher return dollars beyond production inputs than the CT systems. With only a few exceptions the crop rotations have indicated a trend for higher yields and/or returns in the year by year comparisons When averaged across years the NT C-W and C-GS crop rotation systems are doing significantly better than the mono-crop systems. However C and W only systems (especially within the CT tillage system) have done surprisingly well in comparison as all years are considered. This is somewhat tied to the 2007 elevated crop year yields and commodity prices. When the 2007 crop year is removed from the data then the NT Rotation Systems and CT-CW rotation perform significantly better.