Subsurface drip irrigation (SDI) system applies water directly to crop root zone through buried drip line. It is one of the most water use efficient system compared to other systems such as sprinkler or furrow irrigation systems. Some advantages of SDI also include improved nutrient management, potential for improving crop yields and quality, the greater control on water also reduce water and nutrient loss through deep percolation. While on the other side, adoption of SDI systems is still low due to its high initial cost, different management and maintenance requirements since system is installed underground. In Panhandle Nebraska, there are few SDI irrigators. Most SDI irrigators in the area use the system in a dry edible beans-corn rotation system. Overview and management of SDI has been well documented in NebGuide EC776. However, to author’s best knowledge, variety performance of dry edible beans at SDI system in Panhandle Nebraska is unknown. Therefore, the objective of this project is to test performance of different dry edible beans varieties under a SDI system at Panhandle Research and Extension Center (PHREC).
The outcomes of this project include:
The experiment will be conducted at a SDI system at the Mitchell Ag Lab (MAL) of PHREC. The system has 40 management zones in which water can be applied differently. Each management zone will be 600 ft long and 12 rows wide at 22 inches row spacing. Drip tapes will be placed at 12 inches depth and at every other row with emitters set at 27 inches apart. The system is currently being built by a local SDI dealership and expect to finish by end of April, 2019. An illustration of the system is provided in Figure 1. This particular SDI has capability of using lagoon wastewater as its water source. However, clean ground water will be used in this project to avoid complicating experiment results.
Figure 1. Layout of SDI system at Mitchell Ag Lab of PHREC.
A total of 18 management zones will be used for this study, and will be divided into 2 sections. Great Northern and Pinto beans will be planted in each section. In each section, a randomized split block design will be used to conduct the experiment. Irrigation treatment will be used as main plot factor. There will be three irrigation levels: 33%, 66%, and 100% (fully irrigated treatment). Two varieties of great northern and pinto beans will be used as split-plot factor in each section, respectively (Figure 2). Treatments will be replicated 3 times in 3 blocks. Initial soil cores will be extracted at all plots to decide initial soil moisture content, which are crucial for crop emergence at any SDI system. Watermark sensors (Irrometer Inc., Riverside, CA) will be placed at 2 replications of treatment conbinations at 8 inches, 16 inches, and 24 inches depths to monitor soil moisture content. Vinduino R3 data logger (Vinduino LLC, Temecula, California) will be used to record data from Watermark sensors. Irrigation will be triggered once average soil moisture readings at 100% irrigation treatment plot are at 35% depletion level or 33 kilopascal. Irrigation rates at 33% and 66% treatments will be calculated as 33% and 66% of fully-irrigated treatment, respectively. Yields will be recorded using yield monitor on a combine.
Figure 2. Plot layout in one replicate (one block)