Influence of agricultural managed aquifer recharge on nitrate transport: The role of soil texture and flooding frequency

Soil Science Society of America (SSSA) | June 9th, 2021

Agricultural managed aquifer recharge (Ag-MAR) is a concept in which farmland is flooded during the winter using excess surface water to recharge the underlying groundwat

Agricultural managed aquifer recharge (Ag-MAR) is a concept in which farmland is flooded during the winter using excess surface water to recharge the underlying groundwater. In this study, we show how different recharge practices affect NO3− leaching and mineralization–denitrification processes in different soil systems. Two contrasting soil textures (sand and fine sandy loam) from the Central Valley, Califor- nia, were repeatedly flooded with 15 cm of water at varying time intervals in field and soil column experiments. Nitrogen species (NO3–, NH4+, total N), total C, dis- solved O2, and moisture content were measured throughout the experiments. Results show that when flooding occurs at longer intervals (every 1–2 wk), N mineralization increases, leading to an increase of mobile NO3− in the upper root zone and leach- ing of significant quantities of NO3− from both soil textures (137.3 ± 6.6% [sand] and 145.7 ± 5.8% [fine sandy loam] of initial residual soil NO3−) during subsequent flooding events. Laboratory mineralization incubations show that long flooding inter- vals promote mineralization and production of excess NO3− at rates of 0.11–3.93 mg N kg–1 wk–1 (sand) and 0.08–3.41 mg N kg–1 wk–1 (fine sandy loam). Decreasing the flooding frequency to 72 h reduces potential mineralization, decreasing the amount of NO3− leached during flooding events (31.7 ± 3.8% [sand] and 64.7 ± 10.4% [fine sandy loam] of initial residual soil NO3–). The results indicate that implementing recharge as repeated events over a long (multiple-week) time horizon might increase the total amount of NO3− potentially available for leaching to groundwater.

Institutions and the Economic Efficiency of Managed Aquifer Recharge as a Mitigation Strategy Against Drought Impacts on Irrigated Agriculture in California

American Geophysical Union (AGU) | May 28th, 2022

Managed aquifer recharge (or intentional recharge) is a purposeful human intervention designed to supplement natural enrichment processes of groundwater aquifers by vario

Managed aquifer recharge (or intentional recharge) is a purposeful human intervention designed to supplement natural enrichment processes of groundwater aquifers by various methods. It holds the potential to mitigate the impact of climate uncertainty on irrigated agriculture by restoring storage levels in depleted aquifers, the economic value of which increases during droughts. We use a high-resolution dynamic regional hydroeconomic framework that endogenizes farming decisions in response to water quantity-quality changes, as well as complex hydrogeological principles to analyze several institutional designs and climate scenarios applied to the Kings Groundwater Basin in California. Our analysis demonstrates that intentional recharge is of high benefit to the region, potentially increasing average groundwater levels in the region by 20% over a 20 year horizon. Additionally, we show how this practice could become the subject of second-best arrangements among water users in the region in view of property rights to groundwater derived from recent legislation in California, thus increasing its materialization potential. However, we also find that the quantity recharged is sensitive to climate conditions and hydrological properties.

Integrated approaches to understanding and reducing drought impact on food security across scales

Current Opinion in Environmental Sustainability (Elsevier) | October 1st, 2019

Understanding the cross-scale linkages between drought and food security is vital to developing tools to reduce drought impacts and support decision making. This study re

Understanding the cross-scale linkages between drought and food security is vital to developing tools to reduce drought impacts and support decision making. This study reviews how drought hazards transfer to food insecurity through changes in physical processes and socio-environmental systems across a wide range of spatial and temporal scales. We propose a multi-scale, integrated framework leveraging modeling advances (e.g. drought and crop monitoring, water-food-energy nexus, decision making) and increased data availability (e.g. satellite remote sensing, food trade) through the lens of the coupled human–natural system to support multidisciplinary approaches and avoid potential policy spillover effects. We discuss current scale-dependent challenges in tackling drought-induced food security whilst minimizing water use conflicts and environmental impacts. 

Integrated irrigation and nitrogen optimization is a resource-efficient adaptation strategy for US maize and soybean production

Nature Portfolio (Springer Nature) | January 8th, 2025

Climate change poses substantial challenges to agriculture and crop production, but the combined role of nitrogen and water inputs in adaptation has been largely overlook

Climate change poses substantial challenges to agriculture and crop production, but the combined role of nitrogen and water inputs in adaptation has been largely overlooked. Here, by developing regression models using US county-level data (2008–2020), we demonstrate that integrated optimization of irrigation and nitrogen inputs represents the most resource-efficient strategy to offset the climate-related yield losses. Under the 1.5 °C (3 °C) warming scenario, this approach involves increasing irrigation water withdrawals for maize by 62% (67%) and reducing it for soybean by 65% (58%), while increasing nitrogen inputs for maize by 4% (13%) and for soybean by 10% (130%) annually. This strategy reduces unsustainable irrigation water withdrawals by 73% (56%) for maize and 26% (28%) for soybean, enhancing water sustainability. Cost–benefit analysis indicates this optimization is cost-effective for over 80% of US maize and soybean productions, underscoring its critical role for climate change adaptation.

Intensification of hydrological drought in California by human water management

American Geophysical Union (AGU) | January 25th, 2017

Investing In Clean Agriculture: How California Can Strengthen Agriculture, Reduce Pollution And Save Money

Pacific Institute | February 8th, 2005

Global competition, suburban encroachment, tighter regulations, and rising input costs are making farming in California more difficult and, in some cases, less profitable

Global competition, suburban encroachment, tighter regulations, and rising input costs are making farming in California more difficult and, in some cases, less profitable. At the same time, pesticide pollution from farming is causing significant harm to California’s surface and groundwater, air quality, and human health. But there is a way to reduce pesticide use, protect the environment, and help farmers stay competitive according to a new report, Investing In Clean Agriculture: How California Can Strengthen Agriculture, Reduce Pollution And Save Money, published today by the Pacific Institute. “Business as usual isn’t working for our state,” declared Dr. Gary H. Wolff, author of the report and Principal Economist and Engineer with the Pacific Institute of Oakland, California. “Our plan will reduce pesticide use, protect public health, preserve the environment, and help California’s farmers stay competitive in a rapidly changing economy. We think this will be a win for consumers, a win for taxpayers, and a win for agriculture.” A US Geological Survey study of groundwater wells in the San Joaquin-Tulare Basin found at least one pesticide in 59 of 100 samples. But current efforts to reduce pesticide pollution are caught up in the courts. The rebate approach creates a voluntary incentive to reduce pesticide use while leaving it up to farmers to figure out the best way forward. “The Pacific Institute’s innovative proposal will reward farmers who are willing to learn about farming practices that protect water quality,” noted Leland Swenson of the Community Alliance With Family Farmers. “It is a voluntary and incentive-based way for farmers to respond to water quality regulations and keep pesticides out of drinking water.” The report describes how farmers can be rewarded for learning voluntarily about sustainable agricultural practices. A modest increase in the statewide “mill” fee, now levied on pesticides, is returned to farmers who take a short course on sustainable agriculture techniques and storm runoff management. This helps farmers stay competitive while reducing pesticide use – which will protect human health, preserve the environment, and eventually save taxpayers money by reducing medical costs. “Everybody wins if we can reduce our dependence on pesticides,” said Jonathan Kaplan of NRDC. “As the head of California’s Department of Pesticide Regulation just stated, ‘Integrated Pest Management is good for our economy as well as our environment’.” Investing In Clean Agriculture: How California Can Strengthen Agriculture, Reduce Pollution And Save Money estimates that the voluntary program and fee increase could bring $60 million per year into the agricultural sector while also bringing the most cutting edge research on sustainable farming techniques to those in the field.

Irrigated agricultural adaptation to water and climate variability: The economic value of a water portfolio

Journal of Agricultural Economics (Wiley) | December 1st, 2014

Increasing aridity, more frequent and intense drought, and greater degrees of water scarcity create unique challenges for agriculture. In response to these challenges, wh

Increasing aridity, more frequent and intense drought, and greater degrees of water scarcity create unique challenges for agriculture. In response to these challenges, which often manifest themselves as lower and more variable surface water supplies, as well as depleted and degraded ground water supplies, growers tend to seek opportunities to adapt. One option for growers to reduce their exposure to water scarcity and heightened uncertainty is to diversify. Indeed, access to a portfolio of supplies is one way in which water and irrigation districts, as well as individual growers, are responding to the changing landscape of water resource availability. This article evaluates the benefits to irrigated agriculture from having access to multiple sources of water. With farm-level information on 1,900 agricultural parcels across California, we use the hedonic property value method to investigate the extent that growers benefit from having access to multiple sources of water (i.e., a water portfolio). Our results suggest that while lower quality waters, less reliable water, and less water all negatively impact agricultural land values, holding a water portfolio has a positive impact on land values through its role in mitigating the negative aspects of these factors and reducing the sensitivity of agriculture to climate-related factors. From a policy perspective, such results identify a valuable adaptation tool that irrigation districts may consider to help offset the negative impacts of climate change, drought, and population increases on water supply availability and reliability.

Irrigated Agriculture Technologies, Practices, and Implications for Water Scarcity

U.S. Government Accountability Office (GAO) | November 12th, 2019

Demand for freshwater surpasses the amount naturally available in some areas of the United States. The agriculture sector competes for this limited resource, and withdraw

Demand for freshwater surpasses the amount naturally available in some areas of the United States. The agriculture sector competes for this limited resource, and withdraws and consumes the most freshwater of any user in the nation. GAO was asked to conduct a technology assessment around agricultural water use. This report provides an overview of irrigation technologies and on-farm water conservation practices, factors influencing the adoption of these technologies, and implications of their use for water scarcity. In conducting this assessment, GAO reviewed scientific literature; convened an expert meeting with the assistance of the National Academies; visited farmers, academics, and industry representatives; interviewed officials from federal agencies; modeled water use in an illustrative watershed; and performed a regression analysis on U.S. Department of Agriculture irrigation, crop, and technology data. GAO describes two policy options that federal policymakers could consider relating to irrigation technology and discusses their benefits and challenges.

Irrigating Machinery on the Pacific Coast

Scientific American | December 17th, 1887

In offering the present paper to the Institution of Mechanical Engineers, the author does so with a tolerably complete knowledge of the very advanced practice in England

In offering the present paper to the Institution of Mechanical Engineers, the author does so with a tolerably complete knowledge of the very advanced practice in England in this class of machinery: and his purpose is mainly to explain the differences that have been called for by local circumstances in California. Character of the Country: The western or Pacific slope of the Sierra Nevada or coast range of mountains in California is very abrupt, the crests of the range being so near that the snow is visible from the coast during the whole year. Hundreds of streams cross this narrow country, falling either direct into the Pacific Ocean or into the great basin formed by the Sacramento and San Joaquin rivers. These two rivers. the largest in California, run in opposite directions nearly parallel with the coast and meet at the Bay of San Francisco forming ac ontinuous valley 400 miles long and from 50 to 100 miles wide. The small streams for the most part are fed by melting snow in the summer; and every gulch or canon has its rivulet or brook. They increase in volume until they pass into or through the hills at the foot of the mountain range; and there, unless of considerable size, they may wholly disappear in summer by percolation through the silt or by evaporation. Streams exposed to the torrid air which in summer sweeps across the sand deserts of Southern California are dried up with wonderful rapidity. The evaporation from Salt Lake, exposed to the same dry wind, is sometimes equal to half an inch per day. or 64 million tons of water. Not withstanding this great loss by evaporation, the quantity of water falling into the ocean on the coast of California has been estimated at 100 million cubic feet or 2 3/4 million tons per minute, enough, if distributed properly, to irrigate 25,000 square miles.

Irrigation

Scientific American | January 10th, 1903

Irrigation has been practised in America from time immemorial by the town-building Pueblo Indian tribes inhabiting portions of New Mexico and Arizona. Their ancie

Irrigation has been practised in America from time immemorial by the town-building Pueblo Indian tribes inhabiting portions of New Mexico and Arizona. Their ancient canals may still be traced across the broad valleys. through which are scattered the almost innu merable ruins of community dwellings. On the mesas of southwestern Colorado and adjacent portions of Utah, Arizona, and New Mexico are found the wonderful cliff dwellings, and in the little valleys near these may be seen ditches which were in use perhaps a thousand or more years ago.