Location: Water Management Research
2019 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 and evaluate capacity of biochar to stabilize microbial community response to deficit irrigation.
• 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 in biochar-amended soil can increase crop water use efficiency and mediate changes in soil microbes. Plot experiments with different biochar and irrigation are planned for bulb onion. Crop yield, quality, and soil microbes 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.
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 plot-scale field experiment was carried out using the same biochar and irrigation treatments as in the previous 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. As in the previous year, plant growth parameters measured include height, weight, leaf number, bulb diameter; and at harvest time, bulk yield, size, and soluble solid contents were measured.
Under Sub-objective 1B, the newly grafted orchard received full irrigation, under furrow, drip, and micro-sprinkler systems, to continue with the experiment of establishing the newly budded trees. As in the previous year, dendrometer measurements were continued 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. The goal was to determine whether grapevines would recover from the water stress imposed by deficit irrigation. The Scarlet Royal grapes were tested in a farmer’s vineyard in the Central Valley of California. 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 onsite.
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, i.e. pistachio trees, in the current project. Multi-year field trials are being conducted in both drainage sediment and in saline soils on the west side of the San Joaquin Valley of California on prickly-pear cactus, poplar trees, mustard, agretti, different ecotypes of guayule, pomegranate, and pistachio trees. All crops are being drip-irrigated with drainage water containing salinity, boron, and selenium. All tested plant species, especially agretti, thrive under the tested saline growing conditions. Selenium-enriched agretti, cactus fruit, and pistachio nuts were produced and can be utilized as selenium-enriched food crops, while the quality and quantity of latex produced from guayule plants is currently being analyzed in conjunction with the Western Regional Research Center in Albany, California. Long-term sustainability of growing these plant and tree species is being investigated under these saline conditions.
Under Objective 2, laboratory experiments were conducted to determine the interaction between biochar and nitrogen (N) and evaluate the ability of biochar to retain N in soil and pH effects. Adsorption of major mineral N species (ammonium and nitrate) on seven biochar products that were prepared from different feedstocks and pyrolysis temperatures were determined. The data show that most biochar products cannot adsorb nitrate, which is the dominant N species in most agronomic systems under unsaturated conditions. The result implies that biochar amendment is unlikely to reduce leaching loss. Biochar can adsorb ammonium, but the adsorption is highly pH dependent. The maximum adsorption occurs at pH between 8-9 and the adsorption amount decreases as pH increases or decreases. Stepwise regression analysis shows that carbonates, organic carbon and previous moisture condition of biochar explain 99 percent of the variability in the adsorption coefficient.
A second-year field experiment was conducted to continue to investigate if biochar can improve N availability to plants, to increase N use efficiency, and reduce volatilization and leaching losses. The objective was to determine the effects of biochar type, application rate, and in combination with composted manure on the fate of N and crop yield. Treatments included two biochars (from feedstock softwood or almond shells at 500 or 550 degrees Celsius (C) pyrolysis temperature, respectively), two biochar amendment rates (20 and 40 tons/hectare), and biochar amendment in combination with composted manure. Processing garlic were planted in October 2018. Nitrate leaching samplers were installed prior to planting and ammonia volatilization was monitored during the growing season. Garlic was harvested in July 2019. Plant and soil samples as well as the N leaching samples are being collected. All samples will be analyzed to determine the fate of N fertilizer applied.
In collaboration with University of California (UC) Cooperative Extension, new research projects were initiated to investigate whole orchard recycling (WOR) impact on tree performances and greenhouse gas (GHG) emissions. Two fields have been established: one in 2017 at a commercially owned almond orchard and the other in spring 2019 at the University of California Kearney Agricultural Research and Extension Center. Both fields included woodchip incorporation rate at 60 tons/acre. Control plots without woodchips are included for comparisons. New almond trees were planted following the incorporation of woodchips into surface soil in both fields. Greenhouse gas (GHG) nitrous oxide (N2O) and carbon dioxide (CO2) emissions have been measured. Data have shown that GHG emissions are always higher from woodchip incorporated plots than the control. There are large seasonal and spatial differences, especially for woodchip incorporated plots. The CO2 emission rates are always higher from tree rows (berm) than alleyways during the growing season, but during the winter rainy season, CO2 emissions in alleyways exceeded those from tree rows on the berm, indicating the importance of water availability in woodchip degradation rate. For N2O, however, tree rows where N fertilizer is applied always show higher emissions than alleyways. It should be noted that although GHG emissions are high from woodchip incorporation, WOR provides many advantages over burning. Burning is one of the most common practices for orchard waste disposal, which immediately releases most carbon as CO2 to the atmosphere and contributes to the severely degraded air quality in the region. Woodchips in soil can promote microbial activities and improve overall ecological health. One of the major concerns for soil incorporation of woodchips is competition for N from crop needs because N is required during biomass decomposition. Thus, proper N supply may be needed especially in the first few years, which is one of the objectives we are addressing in the second field experiment by testing different N application levels on tree performance and N losses via GHG emissions and leaching.
Accomplishments
1. Field management practices to reduce nitrogen gas emissions. Soil fertilization is the largest source of greenhouse gas nitrous oxide (N2O) emissions and management practices that can reduce its emissions need to be identified. The influence of drip irrigation on N2O emissions was investigated by ARS researchers in Parlier, California, in an onion field for two years. The field included two irrigation systems: traditional surface drip irrigation and subsurface drip irrigation with three nitrogen (N) application rates. Both years’ data show that N2O emissions from surface drip especially at a relatively higher application rate were over an order of magnitude higher than those from subsurface drip. N2O emissions have a high and positive correlation with N fertilization events and application levels. This research demonstrated that although N fertilization is a major cause for N2O emissions, subsurface drip irrigation/fertigation can significantly reduce N2O emissions.
2. Development and identification 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 in poor-quality soils. ARS 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, mustard, 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. All tested plants and trees produced selenium-enriched plant products. The use of alternative drought-, salt-, and boron-tolerant crops already identified with these studies should be considered as alternative crops for growers who have limited high-quality water in the western U.S.
3. Microbial responses to management practices influence soil nitrogen cycling. Microbial drivers influence soil nitrogen (N) cycling processes, which can lead to nitrate leaching and nitrous oxide release from soils, and these N losses contribute to groundwater contamination and greenhouse gas emissions, reduce soil fertility, and increase N fertilizer demands. Studies by ARS researchers in Parlier, California, evaluated microbial community responses to management practices (grazing and flooding) and their corresponding influences on N-cycling processes. Results identified spatial patterns across microbial communities that are critical to predict their N-cycling functions and the functional potential of microbial groups, such as soil nitrifiers, shifted in response to light grazing. These results provide insights to the scientific community that inform spatial sampling strategies and methodology to indicate subtle community shifts that result in significant functional changes. Furthermore, the sensitivity of the N-cycling microbial community to flooding and grazing can inform farmers of management strategies and fertilizer application timing that best promote retention of soil N.
4. Soil moisture and temperature impact microbial community stability and carbon cycling. The responses of soil bacterial and fungal communities to varying moisture and temperature conditions will impact soil carbon (C) stability. Soil carbon is essential to maintain well-structured soils that reduce contaminant and nutrient leaching, facilitate water infiltration and storage, and support root development. ARS researchers in Parlier, California, demonstrated that biomass harvest and altered precipitation and temperature resulted in faster successional shifts of both bacterial and fungal communities. Profiles of fungal genes involved in C-cycling were determined more by climate factors than those of bacterial communities, which largely reflected soil conditions. These results are essential for predicting ecosystem-scale C cycling and how this may vary in response to variations in soil moisture and temperature. These findings will be important to scientists attempting to model soil C cycling, policy makers interested in C sequestration, and farmers wishing to improve soil health by increasing soil organic matter.
Review Publications
Ma, X., Zhang, Q., Zheng, M., Gao, Y., Yuan, T., Hale, L.E., Van Nostrand, J.D., Zhou, J., Wan, S., Yang, Y. 2019. Microbial functional traits are sensitive indicators of mild disturbance by lamb grazing. Journal of the International Society for Microbial Ecology. 13:1370-1373. https://doi.org/10.1038/s41396-019-0354-7.
Zhao, M., Sun, B., Wu, L., Wang, F., Wen, C., Wang, M., Liang, Y., Hale, L.E., Yang, Y. 2019. Dissimilar responses of fungal and bacterial communities to soil transplantation simulating abrupt climate changes. Molecular Ecology. 28(7):1842-1856. https://doi.org/10.1111/mec.15053.
Gao, S., Hendratna, A., Zejiang, C., Duan, Y., Qin, R., Tirado-Corbala, R. 2019. Subsurface drip irrigation reduced nitrous oxide emissions in a pomegranate orchard. International Journal of Environmental Science and Development. 10(3):79-85. https://doi.org/10.18178/ijesd.2019.10.3.1151.
Gao, Q., Yang, Y., Feng, J., Tian, R., Guo, X., Ning, D., Hale, L.E., Wang, M., Cheng, J., Wu, L., Zhao, M., Zhao, J., Wu, L., Qin, Y., Qi, Q., Liang, Y., Sun, B., Chu, H., Zhou, J. 2019. The spatial scale-dependency of diazotrophic and bacterial community assembly in paddy soil. Global Ecology and Biogeorgraphy. 28(8):1093-1105. https://doi.org/10.1111/geb.12917.
Guo, X., Zhou, X., Hale, L.E., Yuan, M., Ning, D., Feng, J., Shi, Z., Li, Z., Feng, B., Gao, Q., Wu, L., Shi, W., Zhou, A., Fu, Y., Wu, L., He, Z., Van Nostrand, J.D., Qiu, G., Liu, X., Luo, Y., Tiedje, J.M., Yang, Y., Zhou, J. 2019. Climate warming accelerates temporal scaling of grassland soil microbial biodiversity. Nature Ecology and Evolution. 3:612-619. https://doi.org/10.1038/s41559-019-0848-8.
Anjos, D.C., Hernandez, F.F., Banuelos, G.S., Rana Dangi, S., Tirado-Corbala, R., Da Silva, F.N., Filho, P.F. 2018. Microbial community and heavy metals content in soils along the Curu River in Ceara, Brazil. Geoderma Regional. 14:e00173. https://doi.org/10.1016/j.geodrs.2018.e00173.
Yu, Q., Shah, K., Wang, D., Ma, Y., Wang, Z. 2019. Model based study of crop evapotranspiration under canopy shading. Agronomy. 9(6):334. https://doi.org/10.3390/agronomy9060334.
Nguyen, K., Cuellar, C., Mavi, P., Leduc, D., Banuelos, G.S., Sommerhalter, M. 2018. Two poplar hybrid clones differ in phenolic antioxidant levels and polyphenol oxidase activity in response to high salt and boron irrigation. Journal of Agricultural and Food Chemistry. 66(28):7256-7264. https://doi.10.1021/acs.jafc.8b01106.
