Location: Northwest Irrigation and Soils Research2016 Annual Report
Objective 1. Determine the effects of fertilizer source and fertilizer additives on nutrient budgets in irrigated agricultural systems. (Tarkalson 0.5, Leytem 0.5, Dungan 0.2, Ippolito 0.15). Subobjective 1.1. Identify effects of fertilizer source, and nitrification and urease inhibitors on ammonia and greenhouse gas emissions from soils under irrigation. Subobjective 1.2. Identify effects of fertilizer source, and nitrification and urease inhibitors on carbon, nitrogen, and phosphorus cycling and losses from soils under irrigation. Subobjective 1.3. Identify effects of fertilizer source, and nitrification and urease inhibitors on crop nutrient removal from soils under irrigation. Objective 2. Develop utilization practices for agricultural byproducts to increase nutrient and water use efficiency. (Lentz 0.5, Lehrsch 0.4, Ippolito 0.1). Subobjective 2.1. Identify effects of biochar and other amendments on soil carbon, nitrogen, and micronutrient budgets and water availability over time. Subobjective 2.2. Identify the effects of agricultural byproducts and soil water content on the emissions of carbon dioxide and nitrous oxide gases from freezing and thawing soils.
The research for all objectives will be conducted at the ARS Northwest Irrigation and Soils Laboratory in Kimberly, ID. Project objectives will be achieved through three main studies conducted at different scales to improve our understanding and management of soil nutrients. Research for Objective 1 involves a five year field study comparing soil ammonia and greenhouse gas emissions, soil nutrient cycling and crop nutrient uptake from selected fertilizer or manure treatments combined with nitrification and urease inhibitors. More detailed field and laboratory studies will be used for Objective 2.1 to identify the effects of biochar and other amendments on nutrient cycling. Research in Objective 2.2 entails a laboratory study to collect detailed information about greenhouse gas emissions from soils during freeze thaw cycles. This project will broaden scientific knowledge of nutrient cycling in the agricultural fields to which dairy manures and fertilizers are applied, determine if selected agricultural byproducts and amendments can assist in managing nutrients and reducing emissions in arid agricultural systems, and help us better understand nutrient cycling within the broader system through validated process based models. Data from this project will be provided to scientists and organizations to improve and validate nutrient cycling models, and for other related analysis (USDA and USEPA greenhouse gas inventories, the Integrated Farm System (IFSM) model, the Voluntary Reporting of Greenhouse Gases Carbon Management Evaluation Tool (COMET-VR), the Daily Century Model (DayCent), and Dairy Management Inc. life cycle analysis).
This is the final report for project 2054-12000-010-00D which expired July 2016. Research will continue under the new project 2054-12000-011-00D "Improving Management Practices for Irrigated Western Cropping and Dairy Systems to Contribute to Sustainability and Improve Air Quality,” which began in July 2016. Studies were initiated in 2013 to determine the effects of fertilizer source and fertilizer additives on nutrient budgets in irrigated agricultural systems. These studies will continue as part of the new project. One study is comparing the effects of manure, compost, commercial fertilizer or SuperU (an enhanced-efficiency nitrogen fertilizer) on soil gas emissions, crop yield, crop nutrient uptake, and soil nutrient cycling. The greenhouse gas emissions data from 2013-2015 showed that SuperU treated plots emitted 52% less nitrous oxide compared to urea in 2013 when corn was grown, while no nitrous oxide emissions reduction occurred in 2014 when barley was grown. The nitrous oxide emission losses as a percentage of total nitrogen applied were 0.31% and 0.15% for urea and SuperU in 2013, respectively, with losses of 0.65% from both urea sources the following year. Cumulative daily nitrous oxide emissions between fall and spring manure application were not significantly different; however, these treatments produced the greatest emissions in 2014 and 2015 (3.5- and 1.9-fold greater than urea, respectively). Cumulative carbon dioxide emissions were greater from fall and spring manure than the other nitrogen fertilizers during the first two years of the study, but there was no lasting effect of manure on emissions during alfalfa production. Methane emissions were negative (cumulative values ranging from -416 to -221 g/ha) and no differences occurred among the treatments, including the control plots which did not receive any fertilizer. Negative values indicate that the soil was removing methane from the atmosphere. Silage corn, barley grain, and alfalfa yields were statistically similar among all fertilizer treatments including the unfertilized plots. Although manure application timing did not affect cumulative greenhouse gas emissions, this work demonstrates that SuperU can potentially reduce nitrous oxide emissions from irrigated cropping systems in the semiarid western United States without decreasing crop yield. Two studies were initiated to evaluate current nitrogen fertilizer recommendations for corn and sugar beet. In 2014 and 2016, eight commercial nitrogen fertilizer rates were applied to soils that had received dairy manure or commercial fertilizers from 2004 to 2009. The data will be summarized in FY 2017 and submitted for inclusion in a peer-reviewed journal. The second study was initiated to update commercial nitrogen fertilizer recommendations for irrigated corn in the Pacific Northwest. In 2016, four site-years were added to the database. Initial results show that corn silage and grain yields often do not increase with nitrogen applications and current University of Idaho fertilizer recommendations are too high. This study will continue as part of the new project plan. Studies identifying the effects of biochar and other agricultural byproducts on soil nutrients and water were completed. The results were presented at various conferences and published in three peer-reviewed papers. In summary, greenhouse gas emissions and nitrogen cycling results from a five-year field experiment showed that amending soils with biochar, a byproduct of bio-oil production, could remove excess atmospheric carbon dioxide while improving soil quality. Compared to untreated soil, biochar produced a consistent increase in soil carbon, but had little effect on other soil nutrients. The biochar had few effects on corn silage nutrient concentrations and silage yields until the second growing season, when it reduced nitrogen and sulfur concentrations in silage and reduced yield relative to untreated soil. Combining biochar with manure eliminated potential yield reductions from biochar while increasing nitrogen availability from manure. Laboratory incubation microcosm experiments showed that biochar application rates of 10 and 20 tons per acre improved the soil water holding capacity, yet application rates greater than 20 tons per acre led to significant decreases in plant-available soil nitrogen and significantly altered the microbial community structure. A recommended biochar application rate of 10 tons per acre was established to improve soil water retention without altering microbial community composition. A freeze-thaw study with soil columns revealed that freeze-thaw cycles (i) caused soil water to redistribute, (ii) interacted with water content to alter the near-surface aggregate stability of wet soil, and in turn (iii) affected the emissions of greenhouse gases during both freezing and thawing. As manured soil was frozen, nitrous oxide emissions decreased by a factor of four. In contrast, when intact cores of once-frozen manured soil were thawed slowly at only +2° C, concentrations of carbon dioxide increased by a third and of nitrous oxide increased by a factor of eight, each peaking 24 to 26 hours (h) after thawing began, compared to the ambient concentrations in the headspace above the cores. Unexpectedly, emissions of nitrous oxide during thawing were less from freshly manured soil than soil that had received manure annually. Experimental findings, in conjunction with the review of newly available literature, suggests that greenhouse gas emissions that occur during (i) nightly light freezes in late fall and (ii) daily thaws in early spring may contribute substantially to overwinter (or non-growing season) emissions, providing direction to future research efforts.
1. New, lower nitrogen fertilizer recommendation for optimum sugar beet yield. Nitrogen management is critical in sugar beet production to optimize yield and extractable sugar. Current nitrogen fertilizer recommendations for sugar beet in Idaho are seven pounds of nitrogen per ton of beet, including nitrogen in the soil and applied fertilizer. ARS researchers in Kimberly, Idaho, in collaboration with agronomy staff at Amalgamated Sugar Company, used 14-site years of data to determine that nitrogen requirements could be reduced by 14 to 29% in the Pacific Northwest compared to current recommendations. The average nitrogen recommendation to achieve maximum sugar yield was 4.5 pounds of nitrogen per ton beet. The new nitrogen recommendations will result in significant cost savings for farmers and less nitrogen loss to the environment.
2. Enhanced-efficiency nitrogen fertilizers can reduce nitrous oxide emissions from cropping systems. Nitrous oxide gas emitted from soil represents lost nitrogen and nitrous oxide is also a potent greenhouse gas. ARS researchers in Kimberly, Idaho, monitored greenhouse gas emissions from a silage corn–barley–alfalfa rotation that received a stabilized urea fertilizer (SuperU) or conventional granular urea in the spring, or dairy manure in the fall or spring. They found that SuperU reduced nitrous oxide emissions by 52% when corn was grown, but nitrous oxide emissions were not reduced when barley was grown. There also was no difference in emissions between spring and fall manure applications. Nitrous oxide emissions from the soil were less than 1% of the applied nitrogen. This work demonstrates that SuperU can reduce nitrous oxide emissions from irrigated cropping systems in the semiarid western United States.
Lehrsch, G.A., Brown, B., Lentz, R.D., Johnson-Maynard, J.L., Leytem, A.B. 2016. Winter and growing season nitrogen mineralization from fall-applied composted or stockpiled solid dairy manure. Nutrient Cycling in Agroecosystems. 104:125-142.
Lehrsch, G.A., Brown, B., Lentz, R.D., Johnson-Maynard, J.L., Leytem, A.B. 2015. Compost and manure effects on sugarbeet nitrogen uptake, nitrogen recovery, and nitrogen use efficiency. Agronomy Journal. 107(3):1155-1166.
Ippolito, J.A. 2015. Aluminum-based water treatment residual use in a constructed wetland for capturing urban runoff phosphorus: Column study. Water, Air, and Soil Pollution. 226(10). doi: 10.1007/s11270-015-2604-2.