2013 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.
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.
An existing drip irrigation system was used with peanut, cotton, and corn to help identify best irrigation techniques. Irrigation events were scheduled at three irrigation trigger points. Irrigation timing and length of time to irrigate were determined using soil moisture potential sensors to document soil moisture depletion. Water potential sensors were installed at soil depths of 25 and 50 cm in crop rows. Irrigations are scheduled at 40, 60, and 80 kPa (kilopascals) 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. Yield data were collected and correlated with soil water potential. Crop water use efficiency for was determined for each crop and irrigation trigger point. Crop water use efficiency data versus irrigation trigger points can be used by growers to select the best irrigation trigger point for their crop when irrigated with drip irrigation.
Peanut peg strength. Previous research has shown that the best time to harvest peanut is by using hull color. This works well but is time consuming. This hull color may show approximate harvest date but does not take into account peg strength. Pod color may indicate it is time to harvest, however, if peg strength is strong enough, harvest could be delayed to allow younger peanuts to mature. Immature peanuts could reduce total yield, increase possible risk of aflatoxin during storage, and during roasting cause off flavors. Using peg strength as a determinate of when to harvest along with hull color, growers could possibly increase yield. Peanuts in the warehouse should have less risk for aflatoxin, and food processor would have less risk of off flavors during roasting. The objective of this research is to determine value of peg strength as a determination of when to harvest peanut. Peg strength and yield data indicate a relationship such that as peg strength increased so did yield. However, the difference in the average peg strength from the lowest to the highest pod yield is only 0.24 lbs/in2 and the differnce between the averge highest and lowest peg strength is 0.6751 lbs/in2. This is a relatively small values to try to measure and to predict when to harvest to get the greatest yield. Overall peg strength may not be a good determinent of when to harvest.
Long term peanut yield with various irrigation rates. Long term peanut yield with various irrigation rates and crop rotations irrigated with subsurface drip irrigation (SSDI) is not known for U.S. southeast. A SSDI system was installed in 1998 and maintained for 10 years. The soil was Tifton loamy sand and consisted of three crop rotations, two drip tube lateral spacings, and three irrigation levels. Drip tube laterals were installed underneath each crop row and alternate row middles. Crops were irrigated daily at 100, 75 and 50% of estimated crop water use. Laterals spaced at 1.83-m had the same yield as laterals spaced at 0.91-m in nine out of ten years. Over the 10-year period of this research, the 50, 75, and 100% irrigation treatments averaged 3263, 3468, and 3497 kg ha-1, respectively. The 50% irrigation treatment showed lower yields two out of ten years than the 100% irrigated treatment and no significant yield difference between the 75 and 100% irrigation treatment. This implies a 25% saving of water without compromising crop yield. Crop rotation significantly affected peanut yield seven out of eight years and in all cases continuous peanut had the lowest yield. Conversely, higher yields were measured in rotations with longer time periods between peanut crops. Irrigation treatment had no effect on percent total sound mature kernels (TSMK). Lateral spacing affected TSMK two out of ten years or 20% of the time. Crop rotation affected TSMK almost 90% of the time. Continuous peanut rotation had the lowest TSMK with higher percentages occurring as time between peanut crops increased. There was no clear evidence of any crop rotation affecting kernel size distribution. The use of deep subsurface drip irrigation is feasible for peanut and associated crop rotations.