2010 Annual Report
1a.Objectives (from AD-416)
1. Develop more efficient management practices for conventional tillage systems with respect to agricultural water use for row crops (cotton, corn, and peanut).
2. Develop improved techniques for irrigation scheduling of surface drip irrigation for row crops and vegetables.
3. Develop management techniques for new and emerging crops in peanut-base rotations irrigated with surface drip.
4. Develop improved technologies for the use and management of drip irrigation in cotton, corn, and peanut rotations.
1b.Approach (from AD-416)
Furrow diked, and non-furrow diked treatments will be applied in a strip-split-plot design with irrigation as main plots and furrow diking as sub-plots with a non-irrigated control. In furrow diked treatments, furrow diking will be conducted after planting, near or before seedling emergence. The basins and dams formed by the 2-paddle furrow diker are commonly 1.5 m long, 0.30 m wide, and 0.2 m deep. The ripper shank will be operated at a depth of about 20 cm in every row middle of furrow diked treatments. Furrow dikes will be created in alternate rows, leaving traffic row middles non-diked. Irrigation timing and amount will be determined using IrrigatorPro. Soil and plant parameters will be monitored using electronic sensors. A rainfall simulator will be used to document soil erosion and infiltration from various treatments and soil series. Meteorological factors will be continuously monitored and recorded using electronic weather stations. Agronomic and economic factors will be recorded for each crop throughout the season and reported as a whole to determine the feasibility of each system. Crop yield, quality, and economic factors will be recorded and compared to express the feasibility of these systems. Agronomic management in field studies will be with current best management practices including transgenic herbicide and insecticide systems. Surface drip irrigation (SDI) will be used to document irrigation strategies for peanut, cotton, corn, vegetable, wheat and canola that will promote economic yield. Crop rotations will have four irrigation treatments and three replications in a randomized complete block design. Individual subplots will be 5.5 m wide by 15 m long. Irrigation events will occur daily, bi-weekly and weekly. Soil moisture sensors will be used to determine the depth of water to apply at each irrigation event. Mini-lysimeters will be installed to document drainage below the root zone. Vegetable crops will be double cropped with peanut and cotton and irrigated with SDI to help increase the economic opportunity to the grower. At harvest time yield and grade of vegetables will be collected to determine economic feasibility. Yield will be determined by weighing a mass of vegetables at harvest time. Individual vegetable grades will be determined using state inspection criteria where grade criteria are available. Winter wheat and canola will be planted with various nitrogen treatments to document best economic yield. Crop water use for all crops will be documented using soil sensors, mini-lysimeters, and crop yield. Crop yield and grade will be determined using normal procedures for cotton, corn, and peanut. Winter wheat will be tested for protein and falling number to determine economic value. Canola will be tested for percent oil extraction (on site bio-diesel extraction) to determine its value as a bio-diesel crop. Water use curves will be determined for each crop using lysimeter and soil sensor data. Crop coefficients will be calculated from estimated actual potential evapotranspiration collected from lysimeter and weather data, respectively.
Field plots were established in conventional and reduced tillage systems to evaluate furrow diking as a method for water use reduction and water conservation. In previous research, furrow diking in conventional row crop systems has proved to be beneficial in the Southeast. Furrow diking reduces runoff and soil erosion by interrupting surface flow of water during rain storms or irrigation events that produce runoff. Holding more water on cultivated land reduces the need for supplemental irrigation and provides economic stability to non-irrigated row crop production systems. Peanut, cotton, and corn were monitored for irrigation requirements with soil moisture sensors. Irrigation was applied when soil could no longer supply crops with adequate moisture. Furrow diking reduced the amount of irrigation required in corn and cotton crops, which provided economically significant reduction in irrigation required for maximum yield. Reduced tillage systems also limit runoff and erosion by maintaining crop residue from the previous crop on the ground surface. Experiments have been established to determine the long term benefits of reduced tillage and furrow diking as a working system.
In soils with high silt content, the ground surface often seals and reduces infiltration rates. This causes high rates of runoff during rain storms and reduces the ability to effectively supply the crop with water because of the time required to adequately supply the crop with water through irrigation. Mobile soil nutrients and pesticides are very likely to move with water and sediment during runoff. This practice may allow growers to irrigate more economically efficient by facilitating less frequent irrigation through higher irrigation rates per application and reducing fertilizer and herbicide loss from application target areas. In cooperation with ARS from Georgia and Mississippi, experiments were established to evaluate furrow diking with rainfall simulation in peanut and cotton production soils in Mississippi. These studies are a continuation of work started on the Macon Ridge of Louisiana where irrigated corn yield was significantly improved by furrow diking.
Irrigation systems and three irrigation strategies were implemented in peanut, cotton, and corn to help identify best irrigation techniques. Irrigation events were scheduled at three soil water potentials to determine the effects of each irrigation schedule. Irrigation timing and length of time to irrigate were determined using soil moisture sensors to document soil moisture depletion and mini-lysimeters to document drainage. Water potential and water content sensors were installed at soil depths of 25 and 50 cm in the crop row. Irrigations are scheduled at 40, 60, and 80 kPa for all crops. Daily data collected from soil sensors were used to estimate water application depths for each irrigation strategy. Sensors were connected to a datalogger and were interrogated daily to determine irrigation depths using soil moisture depletion. Lysimeters were installed and sensors installed both in and outside the lysimeter.
Economic efficiency of incremental irrigation rates in Southeast cotton (Gossypium hirsutum L.) production. The value of the cotton produced by each of 3 irrigation levels over non-irrigated was converted to the value of lint produced per inch of water applied. In 2 of 8 years, rainfall was above average. In all but one year, irrigation improved yield by 220-575 lb lint/A. Years with average or below average rainfall had incrementally higher yields as irrigation rate increased except for one year. Water use efficiency for irrigation was higher for low irrigation rates. Irrigation provided profit in 7 of 8 years of the study. Reduced irrigation rates have the highest return per unit of water applied, but simply decreasing irrigation level does not maximize efficiency; yield limiting stress must be avoided. Although high rates of irrigation may not be the most efficient, they often provide the most economic return.
Yield and Economics of Shallow Subsurface Drip Irrigation (S3DI) and Furrow Diking in Southwest Georgia. A S3DI system was installed annually in Shellman, GA with and without furrow diking to document yield and economic benefit of these techniques on peanut (Arachis hypogaea L.), cotton (Gossypium hirsutum L.), and corn (Zea mays L.). Research data indicate that installing a drip irrigation system for one year on cotton and corn may be cost effective when compared with nonirrigated cotton and corn production, especially in a drought year. The installation of a shallow subsurface drip system on peanut for one year does not seem cost effective. These data will help growers determine if installing a shallow subsurface drip system will be cost beneficial for their farm.
Sorensen, R.B., Brenneman, T.B., Lamb, M.C. 2009. Peanut Yield Response to Conservation Tillage, Winter Cover Crop, Peanut Cultivar, and Fungicide Rate. Peanut Science. 37(1):44-51.
Sorensen, R.B., Nuti, R.C., Butts, C.L. 2009. Yield and Plant Growth Response of Peanut to Mid-Season Forage Harvest. Agronomy Journal. 101:1198-1203.
Truman, C.C., Nuti, R.C. 2010. Furrow Diking in Conservation Tillage. Agricultural Water Management. 97:835-840.
Truman, C.C., Nuti, R.C., Truman, L.R., Dean, J.D. 2010. Feasibility of using FGD gypsum to conserve water and reduce erosion from an agricultural soil in Georgia. Catena. 81:234-239.