Location: Water Management Research
2018 Annual Report
Objectives
The San Joaquin Valley of California is one of the most productive regions in the world with annual agricultural output exceeding $30 billion. Irrigated agriculture faces severe competition for water from municipal, industrial, and environmental interests; therefore, management strategies must be developed to improve water use efficiency, particularly for perennial crops. Development of management alternatives will require characterization of crop water requirements and determination of levels of irrigation and water quality to sustain production. The overall goal of this multidisciplinary project is to develop new management strategies to increase water use efficiency of both good and poor quality waters and reduce impact on soil and water quality from agrochemicals.
Objective 1: Develop crop water requirements and water management strategies using good quality water, and reuse strategies using poor quality waters, to maintain or improve water productivity.
• Subobjective 1A: Determine effects of deficit irrigation on vegetable crops in biochar-amended soil.
• Subobjective 1B: Determine effects of irrigation methods and deficit irrigation on growth and yield of nectarine budded to existing peach rootstock.
• Subobjective 1C: Determine effects of deficit irrigation on table grape fruit yield and quality.
• Subobjective 1D: Determine water requirements for a mature pomegranate orchard.
• Subobjective 1E: Develop sustainable agricultural water reuse systems to protect soil/environmental health of drainage impacted soils when using poor quality water.
Objective 2: Reduce the detrimental impacts of irrigated agriculture on water quality by developing practices to increase agrochemical use efficiency.
Approach
Objective 1, Subobjective 1A: The hypothesis for this research is that deficit irrigation can increase crop water use efficiency in biochar-amended soil. Plot experiments with different biochar and irrigation treatments are planned for vegetable crops such as bulb onion. Crop yield and quality will be determined and analyzed to assess the interactive effect of deficit irrigation and biochar. If the initial plan with bulb onion is not feasible, other crops will be used as the bioassay crop.
Subobjective 1B: The hypothesis for this research is that grafted nectarine can grow well under different methods of irrigation and deficit irrigation can reduce total water use. This study will be conducted at an existing mature peach orchard that is having nectarine scions grafted to the existing trunks. Furrow, drip, and micro-sprinkler systems will be used under deficit irrigation to determine nectarine yield and quality. If the initial plan for the pre-selected deficit irrigation treatments are too high or too low, adjustments will be made.
Subobjective 1C: The hypothesis for this research is that deficit irrigation will yield quantity and quality of grape products similar to a fully irrigated crop. Field experiments will be carried out at growers’ fields where two table grape varieties will be evaluated for performance under deficit irrigation. If the initial plan at the existing sites need to be changed, we will work with the California Table Grape Commission to find alternative cooperators.
Subobjective 1D: The research goal for this study is that pomegranate water requirement can be determined using weighing lysimeters. This study will be conducted at an existing mature pomegranate orchard. Differential irrigation will be applied for comparison with the deficit treatments. It is not uncommon that there will be down times for the sophisticated mechanical and electronic components associated with the lysimeters. If that happens, we will use soil water content or nearby weather station data for irrigation scheduling.
Subobjective 1E: The research goal for this investigation is that sustainable agronomic systems can be developed for managing soil selenium contributed by use or reuse of poor quality water. We will use drainage waters or poor quality soil and groundwater to grow mustard and canola for biofuel and seed meal production on the west side of the San Joaquin Valley. We will test forage, guayule, and cactus production using micro-plots containing high concentrations of soluble salts, selenium, and boron. If any of the planned research sites is lost, additional research plots can be initiated in areas containing high levels of salt and selenium.
Objective 2: The research goal for this study is to develop feasible and sound management practices to use biochar and manure for irrigated crops to significantly increase nitrogen use efficiency and reduce environmental loss. Both laboratory and field experiments will be carried out for developing management strategies to increase agrochemical use efficiency. If selected biochar and manure do not meet the experimental needs, additional materials will be collected and added to the experiment.
Progress Report
Under Sub-objective 1A, the second year plot-scale field experiment was carried out using the same biochar and irrigation treatments as in the first year. Working with the same farming collaborators, a dehydrator bulb onion was planted as a bioassay crop to evaluate the combined effect of biochar and irrigation treatments on crop growth and yield responses. Field in-situ sensors were installed to measure soil moisture and matric potential, and the data were used as a guide for irrigation scheduling. Plant growth parameters measured include height, weight, leaf number, and bulb diameter. At harvest time, bulk yield, size, and soluble solid contents were measured.
Under Sub-objective 1B, the newly grafted nectarine orchard received full irrigation, under furrow, drip, and micro-sprinkler systems, to continue with the second year experiment of re-establishing the trees. Dendrometers were installed in the spring time to monitor the growth rate of the grafted branches over different methods of irrigation. Soil moisture content was recorded over the three irrigation regimes to determine moisture distribution patterns and availability of soil moisture for root water uptake. Leaf behavior, in terms of photosynthesis rate and stomatal conductance, were measured during the growing season as responses to the three methods of irrigation.
Under Sub-objective 1C, the table grape research at growers’ vineyards was continued from the previous year. Sugraone grapes were tested in a grower field in the Coachella Valley of California where full irrigation was applied after extended periods of different levels of deficit irrigation. The goal was to determine whether grapevines would recover from the water stress imposed by deficit irrigation. Scarlet Royal grapes were tested in a farmer’s vineyard in the Central Valley of California where the growing season is much later in the year. This is a newer variety with little information available on water requirements and response to deficit irrigation. Irrigation rates were monitored with on-site flow meters and irrigation rates determined with crop evapotranspiration estimates from a contractor with instruments installed on each field.
Under Sub-objective 1D, the multi-year field study to determine water requirements for mature pomegranate orchard was continued from the previous year following exactly the same treatments. Four levels of irrigation were applied during the growing season and the initiation of each irrigation event was controlled by the weighing lysimeter located in the middle of the orchard. The duration of each irrigation was proportional to the four levels of water treatments. Fruit yield and quality were determined at harvest and analyzed for treatment effects.
Under Sub-objective 1E, extreme drought conditions and stark reductions in precipitation and available water supplies increased the importance of identifying drought-, salt-, and boron-tolerant plant species that are adapted to grow with high saline drainage or ground waters. Research in the previous project has been extended and includes new salt- and boron- tolerant plant species in the current project. Multi-year field trials are being conducted in both drainage sediment and in saline soils of the west-side of the San Joaquin Valley of California on Opuntia (prickly-pear cactus), poplar clones, agretti, different ecotypes of guayule, and pomegranate. All crops are drip-irrigated with drainage water containing salinity, boron and Se. All tested plant species, especially agretti, thrived under the tested saline growing conditions. Selenium-enriched agretti and Opuntia fruit were produced and can be utilized as food crops, while the quality and quantity of latex produced from guayule plants is being analyzed in conjunction with the Western Regional Research Center in Albany, California. Long term sustainability of growing these plant species is investigated under these saline conditions.
Under Sub-objective 2, both laboratory and field experiments have been conducted to determine the effects of biochar on retaining nitrogen (N) in soil, increasing N use efficiency, and reducing environmental losses in irrigated agricultural systems. Laboratory experiments were carried out to determine adsorption of ammonium and nitrate on seven biochar products. The products were from feedstocks of almond shells, softwoods, coconut shells, bamboo, and green waste that were prepared at pyrolysis temperature of either ~500 or 900 degrees Celsius (°C). The data show that ammonium adsorption on most of the biochar products increased linearly or exponentially as soil N concentration increased. Ammonium concentration on the biochar products was about 10 times or higher than in the soil solution. The data illustrate the potential of biochar to retain N by adsorption of ammonium.
A new field experiment was established in early 2018 to determine effects of two biochars (from feedstock softwood or almond shells at 500 or 550°C pyrolysis temperature, respectively), two biochar amendment rates (20 and 40 tons/hectare), and biochar amendment in combination with either composted manure as an organic N source or chemical fertilizer only. Processing tomatoes were planted in March. Plant growth is being monitored and yield will be measured at harvest in July. Plant uptake and N use efficiency (NUE) will be determined. Ammonia volatilization (major gaseous loss of N) is also being measured during the growing season. Nitrate leaching collectors were installed at 50 centimeter soil depth before planting and will be analyzed by harvest to determine seasonal leaching loss from the various soil amendments. The comprehensive data collection will enable us to perform a mass balance analysis on N and determine effective treatments that would lead to high NUE and minimized N losses to the environment.
Another new field study was established in collaboration with the University of California, Berkeley Cooperative Extension to determine effects of one-time whole orchard recycling with a mulching rate of 60 tons/acre on greenhouse gas nitrous oxide (N2O) and carbon dioxide (CO2) emissions, soil carbon and N dynamics, and nitrate leaching under surface drip-irrigation system in a 35-acre commercially owned almond orchard. The field was previously planted with Westerner Plums (Prunus sp.) in 1998. Trees were removed in late 2017, ground in tub grinders and spread back across the plot area, and then disked into the soil for mulching treatment in four random sites for comparison with and without mulching (control). Almond trees were planted following the incorporation of woodchips into soil, and the field uses a double line surface drip irrigation system. Greenhouse gas N2O and CO2 emissions have been measured since early April 2018. Data from the first two month measurements show that soil respiration rates were much higher with incorporation of woodchips compared to without, but N availability can be very dynamic as N2O emission rates (indication of N transformation) were higher than the control following fertilization but lower in other times. This research continues for three years to gain knowledge on how incorporation of woodchips affects the fate of N in soil.
After two years of study to determine effects of biochar amendment on soil N, volatilization loss, plant uptake, and interaction with irrigation level in an onion field, scientists continue research for the third year by determining soil N status change, N uptake, and leaching loss during the growing season. Treatments include three biochar amendment rates: none, low (29 tons/hectare), and high (57 tons/hectare) and three irrigation levels: 100, 75, and 50% of a reference which provides sufficient water for plant growth. Data from the third year will be evaluated with the previous two year’s data to examine the effects of biochar amendment and interaction with irrigation levels on N.
Accomplishments
1. Remote sensing algorithms developed for determining pomegranate tree water use. Pomegranate has been identified as a crop with potential drought tolerance and high economic value. To manage limited water effectively, ARS researchers at Parlier, California, conducted a field study in experimental orchards using both surface drip and subsurface drip irrigation and irrigation levels at 35, 50, 75, 100% of crop water use. Using a combination of remote sensing instruments and in-situ field methods, orchard canopy ground cover, normalized difference vegetation index or NDVI, canopy-to-air temperature, and fruit yield were measured. There was no difference in tree canopy size between the surface drip and subsurface drip systems, but the 35 and 50% of deficit irrigation treatments significantly reduced tree canopy size compared to the 75 and 100% irrigation treatments. Relationships between NDVI to canopy cover and crop coefficient were established. These functional relationships are potentially very useful for estimating pomegranate tree water use on a field or regional scale using aerial or satellite imagery.
2. Development of alternative crops for drought-, salt-, and boron-tolerance. Extreme drought conditions and stark reductions in precipitation and available high quality water supplies have increased the importance of identifying drought-, salt-, and boron-tolerant plant species that are adapted to grow with high saline drainage or ground waters. Researchers at Parlier, California, conducted multi-year field trials in both drainage sediment and in saline soils on the west-side of the San Joaquin Valley of California, successfully growing salt- and boron-tolerant poplar-tree clones, Opuntia cactus, and agretti. The plants were grown in soils with high levels of salinity, boron, and selenium, and irrigated with drainage waters containing high levels of salt, boron, and selenium. Among the tested plant species, fresh weight yields of agretti were 10-15% higher in nonsaline growing conditions than in soils with high levels of salinity and boron. Approximately 20% of soluble selenium in the saline soil was accounted for in harvested plant materials. The use of alternative drought-, salt-, and boron-tolerant crops like agretti should be considered as an alternative crop for growers who have limited high quality water in the western U.S.
Review Publications
Corwin, D.L., Yemoto, K.K., Clary, W., Banuelos, G.S., Skaggs, T.H., Lesch, S.M., Scudiero, E. 2017. Evaluating oilseed biofuel production feasibility in California's San Joaquin Valley using geophysical and remote sensing techniques. Sensors. 17(10):2343. https://doi.org/10.3390/s17102343.
Centofanti, T., Banuelos, G.S., Zambrano, M.C., Wallis, C.M. 2018. Desert plant for saline and drought stricken farmland: Assessment of Opuntia cactus nutritional characteristics. Journal of Environment and Bio Research. 1(1):1-8. https://www.researchgate.net/publication/321310216.
Centofanti, T., Banuelos, G.S., Wallis, C.M. 2017. Fruit quality of pomegranate grown in arid environment and irrigated with saline water. Sustainable Water Resources Management. 1-14. https://doi.org/10.1007/s40899-017-0191-7.
Zhang, H., Wang, D., Ayars, J.E., Phene, C.J. 2017. Biophysical response of young pomegranate trees to surface and sub-surface drip irrigation and deficit irrigation. Irrigation Science. 35(5):425-435. https://doi.org/10.1007/s00271-017-0551-y.
Gao, S., Doll, D.A., Qin, R., Rana Dangi, S., Gerik, J.S., Wang, D., Hanson, B.D. 2017. Emission and crop response in almond orchards fumigated with reduced rates of Telone® C-35 and low permeability film for nematode control. Crop Protection. 105:80-89. https://doi.org/10.1016/j.cropro.2017.11.010.
Dangi, S.R., Banuelos, G.S., Buyer, J.S., Hanson, B.D., Gerik, J.S. 2017. Microbial community biomass and structure in saline and non-saline soils associated with salt- and boron-tolerant poplar clones grown for the phytoremediation of selenium. International Journal of Phytoremediation. 20(2):129-137. doi:10.1080/15226514.2017.1337073.
