Increasing the Sustainability of Oklahoma Cropping Systems Using Cover Crops

Increasing the Sustainability of Oklahoma Cropping Systems Using Cover Crops

Summary

In June of 2009, wheat from one location near El Reno in western Oklahoma was harvested to evaluate the use of summer cover crop in a continuous winter wheat cropping system. Following wheat harvest, three additional sites were established. Guar, cowpea, soybean, and mungbean were seeded in late June following wheat harvest. Cover crops were terminated after 60 days of growth. Biomass yields were similar; however, cowpea and soybean had a greater amount of TN in the above ground biomass. Wheat grain yield was significantly higher than the traditional fallow.

Objectives/Performance Targets

1. Objective 1 – Determine the effect of cover crops on grain yield of the subsequent wheat crop.

   Objective 2 – Determine nitrogen contribution using the Green SeekerTM Optical Sensor.

Accomplishments/Milestones

In Feb. 2009, the one cover crop plot established in the summer of 2008 was top-dressed based on NDVI. The use of the Green SeekerTM Optical Sensor allowed us to determine the yield potential of each cover crop plot and apply N accordingly. Ramped Calibration Strips applied increasing levels of N in a strip across a fixed distance (100 ft) (Figure 1). The levels applied ranged from 0 to 120 lb N/ac. One Ramped Calibration Strip will be placed in each cover crop. Top-dress application rates are given in Table 1.

Wheat grain yields were significantly higher in the plots that were planted to cowpea when compared to the fallow plots that had no cover crops growing on them during the summer months (Table 2).

Three more plots were established after wheat harvest in June of 2009. Cover crops were terminated in September and planted to wheat in the fall of 2009. Ramped calibration strips were applied in December of 2009.

• Figure 1. Ramped calibration strip in winter 2009.
• Table 1. NDVI values and top-dress N application rates at El Reno in 2009.
• Table 2. Wheat grain yield at El Reno in 2009.

Impacts and Contributions/Outcomes

Three field days were held at the El Reno, Canute, and Hollis location. These field days were organized to highlight the On-farm SARE research project that we have with the producer in each area of southwestern Oklahoma. Seventy-five producers attended and were able to view cover crop plots first hand. We discussed the objectives of the project and what we had seen to date. Data generated from the one location in 2008-2009 has been used in three presentations that had an audience of 185 producers.

Collaborators: