Natural Resources & Environmental Sciences
Non Technical Summary
Irrigated agriculture provides almost half of world food production, but about 20% of irrigated lands are undergoing salinization, which results in reduced or complete loss of crop yields.We will investigate the potential for plants that prefer to grow in salty soils or waters (i.e., halophytes) to produce food for human or livestock consumption, produce biofuel for bioenergy production, and to reduce salt content of soil or nearby water bodies. Specific project objectives are to: 1) characterize growth, yield, and salt uptake rates for halophytic crops; 2) characterize halophytic crop nutritional levels and biofuel potential; 3) examine impacts of halophytic crops on soil and water quality; and 4) model halophytic crop production and salt removal. The intellectual merit of the proposed work is the development of a model that can characterize plant-water-soil salt dynamics to enable assessment of the potential of using halophytes to increase food production or to improve soil and water quality. Such a model does not currently exist. Should this approach prove useful, broader impacts include enhancing food security and benefitting the Nevada and US economy. In addition, the modeling approach developed can be used in other locations in the US and the world. This project directly addresses the research priority of the Nevada Agricultural Experiment Station of air, land and water degradation because of its emphasis on addressing the management of soil and water salinity. The proposal also addresses animal/human nutrition and health because it examines the value of these salt-loving crops to animals and humans. Finally, the project directly addresses the cross-cutting theme of food production by examining the ability of using halophytic crops to improve productivity of agricultural lands.
Animal Health Component
Research Effort Categories
Goals / Objectives
The proposed project's long-term goal is to enhance food security and environmental quality by increasing agricultural production on marginalized saline croplands through the use of halophytic crops. For the purposes of this proposal, we define "marginal lands" as those that have limited options for maintaining or increasing crop production due to soil salinity constraints (CGIAR 1999).
We will investigate these hypotheses through the following tasks:1. Select field plots at Main Station Field lab: Following a preliminary soil survey (see Task 3), we will select field plot locations and construct an irrigation system to them on non-saline and salt-affected lands on the Main Station Farm.2. Planting of halophytic plants at field sites: Four halophytes will be planted: 1) a perennial shrub, Rubber rabbitbrush (Chrysothamnus nauseosus (Pallas) Britt., 2) a perennial grass, AC Saltlander green wheatgrass (Pseudoroegneria spicata x Elytrigia repens), 3) a perennial forb, curlycup gumweed (Grindelia squarrosa (pursh) Dunal), and 4) an annual forb, glasswort (Salicornia europaea). These halophytes represent potential sources of biofuel (rabbitbrush, gumweed), quality livestock forage (AC Saltlander green wheatgrass), and a vegetable product for livestock forage source and direct human consumption (glasswort).The experimental design for the field trials includes halophytes planted with the following treatments:Non-saline soil with irrigation at 100% of evapotranspiration (ET)Saline soil with irrigation at 100% of ET plus appropriate leaching required to leach salts below rooting depth prior to the growing seasonSaline soil with irrigation at 100% of ET with no leachingSaline soil with irrigation at 75% of ET with no leachingSaline soil with irrigation at 50% of ET with no leachingThe ET amount considered 100% of ET will be the real-time reference ET obtained from the Main Station Field lab's on-site weather station. The experimental design will be a randomized complete block with 4 replications. The seeded species will be whole experiments and the irrigation levels will be sub-plots.3. Sampling and analysis of plants, soil, and water for salt ions and nutrient content:a. Soil sampling and analysis: We will assess effects of halophytes on salt accumulation by measuring soil and soil solution chemistry throughout the project. At project start, bulk density and soil texture will be measured for each subplot. Soil salt profiles will be determined at the start and end of the project while soil solution chemistry will be monitored on a monthly basis depending on soil moisture conditions. In addition, previous work indicated the APEX model was sensitive to soil organic carbon content and soil albedo, both of which will be measured at the start and end of the study in each plot.b. Plant sampling and analysis: At completion of the first growing season, perennial plant species (rabbitbrush, AC Saltlander green wheatgrass, curlycup gumweed) will be sampled to determine initial establishment and survival by irrigation treatment. The evaluation will consist of determining plant density and height along the seeded rows. The annual herb (glasswort) will be harvested and weighed to determine biomass production by irrigation treatment. During the remaining years of the project all plant species will be harvested annually, with biomass determined for each species and irrigation treatment. Harvested plants will be analyzed for the fraction of phosphorus and fraction of water in the crop yield. A subset of plants will be sampled monthly to measure parameters for modeling including leaf area index, maximum root depth, above and below-ground biomass, and crop height.4. In vitro digestibility experiments to assess nutrient availability of halophytes for ruminant animals: Digestibility experiments will be performed on harvested halophytes. The dual-flow continuous culture system is an in vitro technique developed by Hoover et al. (1976) that simulates rumen digestion in which different feeds and artificial saliva are mixed with fresh rumen fluid. In the modern version of this system (Soder et al. 2013), temperature, anaerobiosis, and flow rates are tightly controlled. This technique has been widely used to evaluate the effect of complete diets and individual feed ingredients on ruminal digestion, fermentation, microbial protein synthesis, and nutrient flow (Hristov et al. 2012). Advantages of this technique are: 1) ability to test a large number of treatments 2) ability to test high levels of one specific ingredient, 3) reduced experimental time, 4) reduced amount of total feed used, 5) less animal use, and 6) lower cost when compared to in vivo experiments.5. Assessment of halophyte biofuel potential: Plants will be examined for biofuel potential. Extraction methods of two of the plants, curlycup gumweed and rabbitbrush, are well-developed and comparison of production of biofuels from these two plants on saline soils will be very straight forward. For AC Saltlander green wheatgrass, we will utilize standard extraction methods for determining the biofuel production, following milling to 1/8" size in our hammer mill.6. Enhancement of salinity module for public-domain APEX model: Previous work implemented a preliminary salinity module for the APEX model that has algorithms for salt uptake by plants and salt movement through the plants, water and soil (DeRuyter 2014). We will parameterize and calibrate the model using data from the field and laboratory tasks. In Year 4, we will model management scenarios based on input from Extension workshops (see Task 8) to simulate halophytic plant growth and production on lands with varying levels of salinity to estimate potential biomass and biofuel production, salt extraction from soils, and impacts on salt inputs to surface and shallow groundwater to provide a basis to examine the feasibility of halophytes in Nevada's agricultural production systems.7. Outreach to Pyramid Lake Jr/Sr High School: We will recruit students from Pyramid Lake Junior/Senior High School to work for one to two weeks each summer with the project to encourage these students to consider careers in the sciences. We will work with the science teacher at Pyramid Lake Junior/Senior High School to recruit students for this task.8. Involvement of Cooperative Extension: Extension activities for this project consist of several objectives. Extension Objective 1 will begin at project initiation to integrate all research activities with a robust extension educational program aimed at developing a well-trained cadre of professional and lay audiences possessing the skills and knowledge to select and grow appropriate halophytic crops to increase food production on saline soils in dryland ecosystems. These audiences include agricultural producers, production professionals employed by State and Federal agencies, and consultants, and appropriate industry representatives and organizations. Extension Objective 2 involves development and dissemination of extension educational products concerning species selection, required cultural techniques, profit potential and potential production risks. During Year 1, the field research site described in Task 1 will also be established as a field demonstration site as part of Extension Objective 3. This site will demonstrate the economic potential of halophytic species, cultural techniques favoring profitable production, and changes in soil salinity over time. Field-based workshops, tours, small group consultations and intensive on-farm sessions with interested producers will be used in conjunction with the educational products of Extension Objective 2 to develop the skilled cadre of practitioners desired in Extension Objective 1. We will assist early adopters from the Nevada agricultural producer community in establishing off-site demonstration plots on their farms to expand the project's scope and credence with neighboring producers who may be interested in implementing project results, but require more evidence of success before committing to recommended techniques. Extension Objective 4 is to evaluate the project using a variety of techniques applied over the life of the project. Project evaluation will include short-, medium- and long-term evaluations of project success in achieving project goals.