Research Project: Develop Water Management Strategies to Sustain Water Productivity and Protect Water Quality in Irrigated Agriculture

Location: Water Management Research

2022 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
This is the final report for project 2034-13000-012-000D, "Develop Water Management Strategies to Sustain Water Productivity and Protect Water Quality in Irrigated Agriculture," which has been replaced by new project 2034-13000-013-000D, "Improving Soil and Water Productivity and Quality in Irrigated Cropping Systems." For additional information, see the new project report. Under Sub-objective 1A, a dehydrator bulb onion crop was planted each year for three years as a bioassay crop to evaluate the combined effect of biochar and irrigation rates on crop growth and yield. Experiments included three irrigation levels as the main treatments and three biochar amendments as sub-treatments in a split-plot design. Fresh bulb yield showed that biochar treatment had no significant effect but irrigation and interaction with biochar significantly affected the yield. Onion yield at 50% irrigation regardless of whether with or without biochar was significantly lower than those at 75% and 100% irrigation. The yield showed no significant difference between the 75% and 100% irrigation levels. In year four and five, a processor tomato crop was planted each year using the same irrigation and biochar treatments. Regardless of biochar amendment, soil microbial communities shifted substantially in response to deficit irrigation (DI), which was most distinct in the 50% DI treatment as opposed to the 75% DI treatment. Owing to comparable yield and quality in the 75% irrigation compared to full 100% irrigation and lesser impacts on soil microbes, 75% irrigation can be an optimal strategy to reduce irrigation inputs without imposing short- or long-term detrimental impacts on productivity or soil health. Under Sub-objective 1B, the experimental nectarine orchard was irrigated during each growing season to meet tree water requirements using real-time soil moisture data for making irrigation scheduling decisions. Nectarine fruits were harvested and fruit weight and number of fruits per tree were measured. Fruit yield varied from year to year depending on weather conditions and crop development. In the 2021-2022 crop season, fruit yield was 11, 10, and 10 kg/tree and number of fruits per tree was 61, 53, and 55 for furrow, micro-sprinkler, and drip irrigation treatment, respectively. This result indicates that trees under micro-sprinkler and drip irrigation produced larger fruits than under furrow irrigation treatments. Under Sub-objective 1C, the Vineyard-Soil Irrigation Model (VSIM) was applied to provide weekly irrigation recommendations using the table grape variety “Scarlet Royal”. Treatments were grower practice using existing methods based on soil water measurements, and weekly VSIM irrigation recommendation for the entire season based on the irrigation forecast. Scarlet Royal yield data were taken at two harvest picks and total yield was based on 10 harvested vines per replication. Fruit quality was measured at each harvest pick by collecting 50 berries from each replicate/treatment, one day prior to harvest. Results from data analysis confirmed that irrigating Scarlet Royal grape vines with the VSIM weekly recommendations based on a percentage of the previous week’s accumulated crop evapotranspiration (ETc) did not affect its productivity or fruit quality. VSIM treatment did not reduce berry size, weight, or color of Scarlet Royal. After six weeks of cold storage, VSIM weekly recommendation did not increase fruit decay, shattering, firmness, or rachis browning. Under Sub-objective 1D, four levels of irrigation were applied to a pomegranate orchard during the growing season and the initiation of each irrigation event was controlled by a 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. For example, the irrigation water applied for the mature pomegranate orchard was 226, 308, 490, 572 mm for the 35, 50, 75, and 100% irrigation treatment, respectively in 2018. The total rainfall leading to the season was 340 mm, therefore the total water available to 100% evapotranspiration (ET) plot trees was 912 mm for the season. Under the four irrigation treatments, trees produced 77, 74, 68, and 84 pomegranate fruits per tree and weighed 24, 28, 30, and 35 kg per tree. Under Sub-objective 1E, multi-year field trials were conducted in saline drainage sediment and in typical saline soils in the westside of the San Joaquin Valley of California using salt and boron tolerant agretti, guayule, pistachios, mustard, poplar hybrid tree, and Opuntia cactus irrigated with saline, boron (B), and selenium (Se) water. Our goal was to manage selenium with salt and B tolerant crops when irrigating with other sources of poor-quality water under extreme drought conditions. We evaluated the production of cash-value products, including harvestable Se-enriched products. Results from our multi-year trials showed high accumulation of sodium and B in plant tissues, which contributed to slightly lower yields in all crops tested except agretti, as well as low to moderate levels of Se in plant products. Pistachios were shown to tolerate excessive salt and B in irrigation water as young trees under five years of age. In more mature trees of 10-15 years of age, the leaves accumulated excessive levels of sodium and B, which was clearly exhibited as leaf necrosis and resulted in leaf drop. Agretti, poplar hybrids, mustard, opuntia, and guayule displayed no toxicities from saline irrigation from 5-8 dS/m. Selenium and sodium management in the soil will, however, eventually be a necessary management tool when using saline waters long-term for irrigation. Under Objective 2, the role of biochar to retain nitrogen (N) in soil was determined by examining the interactions between biochar and N under different conditions in the laboratory and its influence on crop yield, N uptake, changes in soil N, and environmental losses, including volatilization of ammonia (NH3) and nitrous oxide (N2O), and nitrate (NO3-) leaching under field conditions. All biochar products exhibited adsorption capacity for NH4+, but not for NO3-. The adsorption capacity was affected by feedstocks and pyrolysis temperature. NH4+ adsorption was highly pH dependent, peaking at around pH 9 for all products, but was reduced by more than half at neutral pH. Biochar did not show significant impact on N transformation rate unless soil water content was high. The lab data suggest that biochar products vary tremendously in NH4+ adsorption and their ability to retain NH4+ is likely limited, especially in neutral soils. Three field experiments were carried out to determine if biochar can reduce NH3 and N2O volatilization or NO3- leaching and improve plant uptake. The first experiment evaluated the effects of biochar and interactions with irrigation level on N dynamics in an onion field for three years. There were no significant biochar effects on total N gas emissions or soil NO3- leaching, but significant irrigation effect and interaction with biochar were detected for NO3- accumulation in soil. However, high leaching was associated with biochar amendment and higher irrigation level. These results suggest irrigation strategies are the key to improving N management and developing best practices. The second field experiment evaluated effects of biochar amendment and organic N (org-N) fertilizer in combination with synthetic inorganic fertilizer on N uptake and crop yield by serrano chili pepper for two years. Although pepper yield was highest in 50% org-N and lowest in a high rate (50 ton/ha) biochar treatment during the first year, the effects diminished in the second year. The third field experiment investigated effects of biochar and combination with manure on N dynamics for two years with processing tomato and garlic. All the field experiments showed that although biochar and manure applications improved surface soil organic C and total N content, no significant effects were observed on crop yield, biomass, and N uptake, as well as N gas volatilization and leaching loss. The amounts of N sequestered by plants to be removed from the field at harvest vary tremendously among crops, about half for chili pepper and tomato plants, but 93% by garlic plants. The information is essential to project N fertilization needs to target high use efficiency and minimize environmental losses. This approach is a step forward to improve nutrient management that has been mostly based on correlations between fertilization rate and yield. Laboratory incubations were conducted to monitor the fate of urea fertilizer N spiked in biochar amended and unamended soils by testing three types of biochar, three soil moisture levels, three soil textures, and co-application of biochar with two types of composted manure. A softwood biochar enhanced soil nitrification processes and abundances of nitrifying bacteria. Soil moisture was determined to have a greater impact on nitrification than biochar amendment and amendment impacts differed based on soil texture and presence or absence of manure. The abundances of microbial genes involved in nitrification correlated with soil N species, suggesting that biochar impacts on these communities will influence soil N cycling.

Accomplishments
1. Deficit irrigation (DI) in tomato does not reduce crop productivity or soil health. California agricultural production is increasingly strained by limited irrigation water resources. While DI strategies can save water, it is unclear if there are corresponding declines in crop quality or yield or long-term impacts on overall soil health due to declines in microbial populations. Biochar has potential to ameliorate plant or microbial stress associated with DI. ARS researchers in Parlier, California, demonstrated that biochar with or without compost did not reduce the impact of severe DI on soil microorganisms or crop yield. Microbial communities were only marginally impacted by moderate DI and tomato yield and quality were enhanced, regardless of soil amendment. Also, deficit irrigation induced higher production of extracellular polysaccharides by soil microbes, which is an important component to improve soil structure and moisture retention. This research demonstrates the potential for water savings in tomato production through deficit irrigation.

2. Sustainable agricultural water reuse systems to manage selenium (Se) in drainage impacted soils. Extreme drought conditions and reductions in precipitation and available water supplies increase the importance of identifying drought-, salt-, and boron-tolerant plant species that are adapted to irrigation with poor quality saline drainage or ground waters. ARS researchers in Parlier, California, conducted multi-year field trials in saline drainage sediment and in westside saline soils of the San Joaquin Valley of California on pistachio, mustard, agretti, poplar hybrids, perennial grass species, opuntia cactus, and guayule. The researchers obtained the following yields: pistachio nut yields in older trees ranged 500 to 2000 pounds per acre (lbs/acre), agretti from 10-35 metric tons fresh weight per hectare (FW/ha), guayule rubber and latex 4-14% on a weight per weight basis in the stems, respectively, cactus fruit yields from 10 to 40 metric tons/ha and mustard seed yields from 0.8 to 1.4 tons/acre. In contrast to other species, agretti yields and rubber and latex production from guayule were at least 10% greater when grown under saline conditions. Importantly, approximately 10-20% net losses of soil selenium in the saline soil were accounted for in harvested plant material, and less than 10% was estimated lost by leaching due to minimal precipitation or excessive irrigation. This research allowed collaborators at the Chinese Academy of Sciences in Changchun, China, to identify salt tolerant wetland plant species that manage inorganic contaminants in saline waters.

3. Determination of crop nitrogen fertilization needs using plant residue. Nitrogen (N) fertilization needs for a crop are often determined by correlations between fertilizer application rates and crop yield to achieve a high yield, but the drawback of this approach is that poor soils always need much higher rates and lead to higher losses to the environment compared to soils that can effectively retain N. Two field experiments were conducted by ARS researchers in Parlier, California, to evaluate the effects of biochar, organic N, manure amendment and their combinations on crop yield, N uptake, and environmental losses, and the data were used to assess the N requirement and project fertilization needs. Data for three crops showed that regardless of treatments or field conditions, the amount of N sequestered by a crop was in a stable range: 4.6-6.1, 3.2-3.8, and 9.9-10.0 kg N to produce one tonne of fresh chili pepper fruits, tomato fruits, and garlic bulbs, respectively. The amount of N sequestered by plants to be removed from the field at harvest varied tremendously among crops, about half for chili pepper or processing tomato, but over 90% for garlic plants. These values were used to project fertilization rates for a target yield and use efficiency to ensure sufficient nutrients for plant growth, while minimizing excessive input or loss to the environment. These results help growers and farm advisors develop nutrient management strategies that meet California state waterboard recommendations for addressing nitrate contaminated groundwater.

Review Publications
Duan, Y., Gao, S., Hanson, B.D. 2022. Effects of biochar and fertilizer sources on nitrogen uptake by chilli pepper plants under Mediterranean climate. Soil Use and Management. 38(1):714-728. https://doi.org/10.1111/sum.12759.
Gao, S., Duan, Y., Wang, D., Turini, T. 2022. No significant influence of biochar and manure application on nitrogen fate and sequestration by tomato and garlic crops: A field experiment in California, USA. Soil Use and Management. 38(1):676-690. https://doi.org/10.1111/sum.12749.
Wang, Q., Gao, S., Wang, D., Cao, A. 2022. Biochar significantly reduced fumigant emissions and benefited germination and plant growth under field conditions. Environmental Pollution. 303. Article 119113. https://doi.org/10.1016/j.envpol.2022.119113.
Ye, W., Yuan, L., Zhu, R., Yin, X., Banuelos, G.S. 2020. Selenium volatilization from tundra soils in maritime Antarctica. Environment International. 146. Article 106189. https://doi.org/10.1016/j.envint.2020.106189.
Placido, D.F., Heinitz, C.C., McMahan, C.M., Banuelos, G.S. 2021. Guayule is an industrial crop that can be grown for its natural rubber production and phytoremediation capability in the Western San Joaquin Valley, California. Current Plant Biology. 28. Article 100223. https://doi.org/10.1016/j.cpb.2021.100223.
Wang, G., Bobe, G., Filley, S.J., Pirelli, G.J., Bohle, M.G., Davis, T.Z., Banuelos, G.S., Hall, J.A. 2021. Effects of springtime sodium selenate foliar application and NPKS fertilization on selenium concentrations and selenium species in forages across Oregon. Animal Feed Science and Technology. 276. Article 114944. https://doi.org/10.1016/j.anifeedsci.2021.114944.
Hale, L.E., Curtis, D., Leon, N., McGiffen Jr., Wang, D. 2021. Organic amendments, deficit irrigation, and microbial communities impact extracellular polysaccharide content in agricultural soils. Soil Biology and Biochemistry. 162. Article 108428. https://doi.org/10.1016/j.soilbio.2021.108428.
Hu, Y., Wang, Z., Zhang, Z., Song, N., Zhou, H., Li, Y., Wang, Y., Li, C., Hale, L.E. 2021. Alteration of desert soil microbial community structure in response to agricultural reclamation and abandonment. Catena. 207. Article 105678. https://doi.org/10.1016/j.catena.2021.105678.
Chavez, J., Torres-Rua, A.F., Woldt, W.E., Zhang, H., Robertson, C., Marek, G.W., Wang, D., Heeren, D., Taghvaeian, S., Neale, C.M. 2020. A decade of unmanned aerial systems in irrigated agriculture in the Western U.S. Applied Engineering in Agriculture. 36(4):423-436. https://doi.org/10.13031/aea.13941.
Alizadeh, A., Toudeshki, A., Ehsani, R., Migliaccio, K., Wang, D. 2021. Detecting tree water stress using a trunk relative water content measurement sensor. Smart Agricultural Technology. 1. Article 100003. https://doi.org/10.1016/j.atech.2021.100003.
Helalia, S.A., Anderson, R.G., Skaggs, T.H., Jenerette, D., Wang, D., Šimunek, J. 2021. Impact of drought and changing water sources on water use and soil salinity of almond and pistachio orchards: 1. Observations. Soil Systems. 5(3). Article 50. https://doi.org/10.3390/soilsystems5030050.
Niu, H., Zhao, T., Wang, D., Chen, Y. 2022. Estimating evapotranspiration of pomegranate trees using Stochastic Configuration Networks (SCN) and UAV Multispectral Imagery. Journal of Intelligent and Robotic Systems. 104. Article 66. https://doi.org/10.1007/s10846-022-01588-2.
Tran, T., Dinh, Q., Zhou, F., Zhai, H., Xue, M., Du, Z., Banuelos, G.S., Liang, D. 2021. Mechanisms underlying mercury detoxification in soil–plant systems after selenium application: A review. Environmental Science and Pollution Research. 28:46852-46876. https://doi.org/10.1007/s11356-021-15048-1.
Long, Z., Xiang, J., Song, J., Lu, Y., Yin, H., Zhu, Y., Liu, X., Qin, L., Banuelos, G.S., Wang, Z., Kang, Y., Yuan, L., Yin, X. 2020. Soil selenium concentration and residents daily dietary intake in a selenosis area: A preliminary study in Yutangba Village, Enshi City, China. Bulletin of Environmental Contamination and Toxicology. 105:798-805. https://doi.org/10.1007/s00128-020-02983-x.
Wang, M., Ali, F., Qi, M., Peng, Q., Wang, M., Banuelos, G.S., Miao, S., Li, Z., Dinh, Q., Liang, D. 2020. Insights into uptake, accumulation, and subcellular distribution of selenium among eight wheat (Triticum aestivum L.) cultivars supplied with selenite and selenate. Ecotoxicology and Environmental Safety. 207. Article 111544. https://doi.org/10.1016/j.ecoenv.2020.111544.