Crop rotation, irrigation system, and irrigation rate on cotton yield in southwest Georgia

Authors: Sorensen, Ronald - Ron; Lamb, Marshall; Butts, Christopher - Chris

Submitted to: Crop, Forage & Turfgrass Management
Publication Type: Proceedings
Publication Acceptance Date: 6/29/2020
Publication Date: 7/29/2020
Citation: Sorensen, R.B., Lamb, M.C., Butts, C.L. 2020. Crop rotation, irrigation system, and irrigation rate on cotton yield in southwest Georgia. Crop, Forage & Turfgrass Management. 6:e20053/1-12. https://doi.org/10.1002/cft2.20053.
DOI: https://doi.org/10.1002/cft2.20053

Interpretive Summary: Overhead sprinkler irrigation systems (pivots) are the most common irrigation type in the Tri-state area (AL-FL-GA) because they are quick to assemble (with specialized equipment), durable, and have owner familiarity with operation and maintenance. These overhead systems can cover large areas reducing the cost per area basis but are relatively expensive to install on small areas or in odd shaped fields where the system may not be able to make a complete circle and must backtrack to start over. In contrast, drip irrigation may include precise placement of water and chemicals, low labor requirements, and reduced runoff and erosion compared with overhead sprinkler systems. A drip system has the capability of frequently supplying water to the root zone thereby reducing the risk of cyclic water stress typical of overhead irrigation systems due to travel times from beginning to end of a cycle. Drip irrigation systems can be described as follows: surface drip systems (SDI) where the drip tubing is placed on the soil surface; deep subsurface drip (SSDI) irrigation has drip tubing buried 20 to 30 cm; and shallow subsurface drip irrigation (S3DI) where drip tubing is buried about 5-cm below the soil surface. SDI is traditionally used for high value vegetable/truck crops were the drip tubing is replaced seasonally. SSDI is considered permanent and typically not removed until the life span of the tubing has been reached. S3DI when used with strip tillage production systems may last three to five years or longer depending on crop rotation. With both drip (SSDI and S3DI) and sprinkler systems available to the grower, decisions on which to install are determined by installation expense, field size and geometry, and final crop yield. The grower needs long term yield data to determine which type of irrigation system to install, especially on smaller fields or awkward field geometries. It would also be helpful to know if a specific crop rotation would increase lint yield. The objectives of this research were to determine the long-term yield and quality response of cotton to: 1) three types of irrigation systems, 2) three various irrigation rates, and 3) three crop rotations over a 13 year period. This project was initiated in the spring of 2001 and carried through 2013 crop years at the USDA-ARS Multi-crop Irrigation Research Farm in Shellman, GA (31°44’44”N, 84°36’30”W). The soil type was a Greenville fine sandy loam (fine, kaolinitic, thermic Rhodic Kandiudults) with 0–2% slope. There was a total of seven tiers orientated perpendicular to individual plot rotations. Tiers 1, 2, and 3 were established for an SSDI system. Tier 4 was dryland and S3DI combined, and Tiers 5, 6 and 7 were established for sprinkler irrigation (overhead lateral). Crop rotations with cotton consisted of 1) cotton-corn-peanut, 2) cotton-cotton-peanut; and 3) cotton-peanut-cotton. Irrigation levels for sprinkler were 100, 66, and 33% with a non-irrigated control. Irrigation levels for SSDI were 100, 62, and 50%. There was only one irrigation level for S3DI of 100%. All crop rows were planted on a 0.91-m spacing oriented east and west, perpendicular to the travel of the lateral and parallel the drip tubing. Fertilizer and lime were applied each year for each crop as recommended by soil analysis. Once the crop was planted, all wheeled implements traveling in individual plots were kept to a minimum. The travel bed on each side of the plot was used mainly for spray equipment. Overhead irrigation scheduling (timing and level) was managed by the “IrrigatorPro for Cotton” which is an expert system based on the 100% irrigation level. The average rainfall was 552 mm ranging from a low of 269 mm in 2007 to a high of 907 in 2009. Total rainfall was below average for five out of the 11 years studied. Consequently, as rainfall increased, irrigation amounts for the 100% irrigation

Technical Abstract: Long term yield data would be useful in determining crop rotation, irrigation system selection, and irrigation rate for maximum production and economic sustainability. Research was conducted at the USDA/ARS National Peanut Research Laboratory’s Multi-crop Irrigation Research Farm in Shellman, GA (84°36”W, 30°44”N) on a Greenville fine sandy loam (fine, kaolinitic, thermic Rhodic Kandiudults) soil with 0 to 2% slope. This long term study (2001 to 2013) compared four irrigation systems, three cotton crop rotations, and various irrigation rates on cotton lint yield and quality. Irrigation systems were sprinkler, subsurface drip (SSDI), shallow subsurface drip (S3DI) irrigation, and a dryland control. Irrigation rates were 100, 66, 50, 33, and 0% of estimated water use. Crop rotations were 1) cotton-corn-peanut, 2) cotton-cotton-peanut; and 3) cotton-peanut-cotton (corn = Zea mays L.; cotton = Gossypium hirsutum L.; peanut = Arachis hypogea L.). There was no difference for cotton yield by crop rotation. Sprinkler and S3DI systems had greater lint yield than the SSDI system at the 100% irrigation level when averaged across all years and rotations. Lint yield tended to be lower in high rainfall years without respect to irrigation systems. Irrigation increased lint yield by an average 10% when rainfall was less than average. All fiber quality factors were within acceptable ranges without any value discounts across years, rotation, or irrigation system. Irrigation system selection should not be based entirely on long term yield information, but also on field size, system installation cost, and irrigation system controls and crop management.