澳门六合彩开奖结果走势图

A photo of a young orchard

Growing Crops with Less Groundwater

Growing Crops with Less Groundwater

澳门六合彩开奖结果走势图 Provides Farmers with New Technologies and Tools in Response to Climate Change

On a warm February afternoon, Kirk Pumphrey walks down his rows of almond trees at Westwind Farms in Yolo County. He notices the buds on the branches have already sprouted pink. It worries him. The earlier the trees bloom, the more likely winter frost will damage the nuts. Early blooms are occurring more often as higher temperatures from climate change stimulate plant growth.

California鈥檚 warming climate also means thirstier trees and an increasing reliance on groundwater, especially during drought. found that more water from aquifers last year compared with 2019.

But Pumphrey has tapped 5% less water from these sponge-like underground stores of water in the past year, before the state ended its driest three-year period on record. He鈥檚 managed to save water in part by using a type of precision metering called pulse irrigation. Sophisticated sensors predict when the trees need little pulses of water, just enough to replace the water they lost to the atmosphere the previous day.

鈥淚t鈥檚 the difference between drinking from a firehose or having a glass of water,鈥 Pumphrey said.

Kirk Pumphrey of Westwind Farms stands in front of his rows of almond trees in Yolo County, CA. He's using a precision metering and almond mulch to conserve groundwater. (Karin Higgins/澳门六合彩开奖结果走势图)
Kirk Pumphrey of Westwind Farms stands in his almond orchards in Yolo County, California. He鈥檚 using a precision metering and almond mulch to conserve groundwater. (Karin Higgins/澳门六合彩开奖结果走势图)

 

Pumphrey鈥檚 orchards have become a proving ground for 澳门六合彩开奖结果走势图 scientists at the to test technologies and techniques designed to help farmers conserve groundwater. The center鈥檚 goal is not only to alleviate overpumping 鈥 mining groundwater faster than it is replenished 鈥 but also to help California remain the most productive agricultural state in the nation.

California drought leads to groundwater shortage

鈥淕roundwater is very important to the sustainability of our food systems,鈥 said Isaya Kisekka, director of the and an associate professor of hydrology and agricultural water management in the 澳门六合彩开奖结果走势图 Department of Land, Air and Water Resources, and Department of Biological and Agricultural Engineering. 鈥淚f everyone who is irrigating started to pump groundwater without limitations, it would be a race to the bottom. The water would run out, and we will not be able to produce the very nutritious and unique foods that we produce in California.鈥

Aquifers provide of the water used by the state鈥檚 farms and communities. During drought, they provide nearly 60%.

Overpumping has caused lands to reduced water quality and resulted in higher energy costs, from pumping at greater depths. It鈥檚 dried up some wells, leaving some communities without clean sources of drinking water.

In the San Joaquin Valley, where most of the state鈥檚 food is grown, California overpumps more than 2-million-acre feet of water a year, said 澳门六合彩开奖结果走势图 hydrologist Thomas Harter, a distinguished professor in the Department of Land, Air and Water Resources. An acre-foot is enough water to cover an acre of land a foot deep.

鈥淲ith the megadrought that we are experiencing, even with the rains this winter, that problem has been exacerbated and probably extended to other places in California,鈥 Harter said.

State law now requires managers of the most overdrawn aquifers to bring those basins into balance by 2040. 澳门六合彩开奖结果走势图 researchers are helping farmers adapt.

New technologies to promote groundwater sustainability

Pumphrey, who relies on groundwater, is using the new pulse irrigation technology on all 160 acres of almonds, instead of irrigating them twice a week.

Patrick Brown, a distinguished professor with the 澳门六合彩开奖结果走势图 Department of Plant Sciences, said it鈥檚 a simple concept: Just feed the trees when they need it.

鈥淭he analogy is if you had a pig farm, you wouldn鈥檛 put all the food and all the water down at the beginning of the year and hope it was there at the end. You feed according to the hunger. Trees are not any different,鈥 Brown said.

Kirk Pumphrey, left, and Patrick Brown, a distinguished professor in the Department of Plant Sciences, right, walk through rows of almond trees at Westwind Farms in Yolo County. (Karin Higgins/澳门六合彩开奖结果走势图)
Kirk Pumphrey, left, and Patrick Brown, a distinguished professor in the Department of Plant Sciences, right, walk through rows of almond trees at Westwind Farms in Yolo County. (Karin Higgins/澳门六合彩开奖结果走势图)

Brown is working with Pumphrey on another way to quench the trees鈥 thirst that requires no water. Mulch, a mixture of soft and hard almond hulls, covers the ground beneath the trees. Most growers sell the potassium-rich hulls as cattle feed. But by putting it on the ground, farmers are not only feeding the trees but also saving water.

Pumphrey kicks over the top layer of mulch under his trees to reveal dark, moist soil underneath. He said the mulch helps stop surface evaporation.

鈥淵ou can come out here on a 110-degree day and do this same thing and it will look just like that,鈥 he said.

Kirk Pumphrey's holds the dark hull of an almond in his hands. He's using hulls and shells as mulch in his orchard to increase soil moisture. (Karin Higgins/澳门六合彩开奖结果走势图)
Kirk Pumphrey of Westwind Farms examines the hull of an almond. He鈥檚 using hulls and shells as mulch in his orchard to increase soil moisture. (Karin Higgins/澳门六合彩开奖结果走势图)
Beneath Kirk Pumphrey's feet is almond mulch. He has kicked the top layer off to reveal dark, moist soil underneath the mulch. (Karin Higgins/澳门六合彩开奖结果走势图)
Kirk Pumphrey demonstrates the dark moist soil beneath the mulch in his orchard. (Karin Higgins/澳门六合彩开奖结果走势图)

Mulch may not help some growers. When almond trees are harvested, nuts fall on the ground and machines sweep them up. With mulch on the ground, growers risk contaminating the nuts. But Brown is working with Pumphrey on another project to harvest almonds .

A new machine catches the nuts and recycles the hulls on the orchard floor. The only catch: Farmers must buy the new equipment. But Brown said growers might have a financial incentive. Big buyers of almonds are starting to ask farmers to adopt newer, more sustainable technologies.

Cover crops improve water holding capacity in nut orchards

This winter鈥檚 rains have provided a perfect opportunity for an experiment at another nut orchard, just 12 miles away from Pumphrey鈥檚 farm.  

Nick Edsall, the orchard manager for Bullseye Farms, walks among rows of pistachio trees. Winter cover crops, including knee-high green grasses, vetch and radishes flourish between the rows of trees. Edsall reaches down to pull up a Daikon radish the size of a softball.

Nick Edsall, orchard manager for Bullseye Farms, surrounded by cover crops that grow between the rows of young pistachio trees. The crops are green and lush and grow to knee height. (Gregory Urquiaga/澳门六合彩开奖结果走势图)
Nick Edsall, orchard manager for Bullseye Farms, surrounded by cover crops that grow between the rows of young pistachio trees. (Gregory Urquiaga/澳门六合彩开奖结果走势图)

鈥淚t opens giant pores in the soil,鈥 Edsall said. 鈥淚t鈥檚 doing its job.鈥 

Those giant pores allow rainwater to seep into the ground and help recharge the aquifer, said 澳门六合彩开奖结果走势图鈥 Kisekka, who is using high-tech equipment, including satellites, to monitor soil moisture and groundwater in Edsall鈥檚 orchard.

鈥淚f you have cover crops like this, you鈥檙e going to improve infiltration. You鈥檙e going to improve soil structure, which is going to improve water holding capacity,鈥 Kisekka said.

Cover crops grow on about half of Bullseye鈥檚 5,000 acres of orchards. Edsall said he planted them several years ago to fix a high magnesium problem in the soil that was causing it to crack. Nuts that fell in the cracks couldn鈥檛 be harvested.

Since then, he鈥檚 seen other benefits. The ground crops are attracting pollinators and other beneficial insects and preventing weed growth and water evaporation.

鈥淲ith the ground cover and the roots reaching deep into the soil, when we get a rainfall instead of it running off the field, it runs into the soil,鈥 Edsall said.

During drought, Edsall said he relies solely on groundwater. He鈥檚 seen the demand for it increase as more growers plant permanent crops in the region. 鈥淲ithout any surface water, we鈥檝e been running low. Every year we鈥檙e just crossing our fingers hoping we don鈥檛 run out of water,鈥 he said.

As part of the experiment Edsall is doing with the 澳门六合彩开奖结果走势图 Agricultural Water Center, he has intentionally left a section of orchard with no cover crops. Even with this winter鈥檚 procession of atmospheric rivers, water did not seep deep into the soil there.

鈥淲here we don鈥檛 have anything planted the water runs to the end of the field and pools and puddles and it eventually either runs into a drain or it sits on the field for multiple days to weeks,鈥 he said.

Edsall said a lot of growers are hesitant to plant cover crops because they also require water. Like any additional crop, they also require more labor.

Cover crops promote soil health and carbon sequestration

Edsall is hopeful 澳门六合彩开奖结果走势图 researchers can provide some solid data to discover if cover crops save water in the long run and if they have other big payoffs, such as increasing soil moisture and health, recharging groundwater and even storing carbon in the soil.

Kisekka said the satellite images he鈥檚 taken of Edsall鈥檚 orchard after a series of atmospheric rivers show promise.

 

A map of soil moisture derived from satellite remote sensing of Bullseye Farms. It shows a square of green with the southwest quadrant in orange. The orange quadrant is the block of the orchard with no cover crops.The map shows the orange block has 1% less soil moisture in the root zone.
A map of soil moisture derived from satellite remote sensing at Bullseye Farms. The southwest quadrant in orange is the block of the orchard with no cover crops. This shows that block having 1% less soil moisture in the root zone. (Isaya Kisekka/澳门六合彩开奖结果走势图)

 

鈥淚 could see a very clear difference between the block in this orchard that are cover cropped and the block of the orchard that are not cover cropped,鈥 he said. Satellite remote sensing shows the block without cover crops has 1% less soil moisture in the root zone.

One of the goals of the experiment is to improve satellite algorithms so water managers can measure water use more accurately in California.

Matt Roby, a research scientist with the U.S. Department of Agriculture, is collaborating with Kisekka. He鈥檚 using a tall structure, called an eddy covariance flux tower, to measure evapotranspiration, or how much water is lost from cropland to a thirsty atmosphere. It also measures the carbon dioxide exchange in the ecosystem.

鈥淏ased on changes in the flow of those gases, we can determine if carbon dioxide is either taken up or released from the landscape and how much water is released into the atmosphere,鈥 he said.

ullseye Farms orchard manager Nick Edsall, left, with 澳门六合彩开奖结果走势图 Agricultural Water Center Director Isaya Kisekka. Kisekka is researching the ability of cover crops to increase soil moisture and groundwater recharge. (Greg Urquiaga/澳门六合彩开奖结果走势图) They stand in a row of green cover crops in an orchard full of young pistachio trees.
Bullseye Farms orchard manager Nick Edsall, left, with 澳门六合彩开奖结果走势图 Agricultural Water Center Director Isaya Kisekka. Kisekka is researching the ability of cover crops to increase soil moisture and recharge groundwater. (Gregory Urquiaga/澳门六合彩开奖结果走势图)
澳门六合彩开奖结果走势图 postdoctoral student Anish Sopkata, left, and USDA research scientist Matt Roby adjust an eddy covariance flux tower, which measures the exchange of carbon dioxide gases and evapotranspiration in the pistachio orchard. They are tilting a tall metal tower diagonally in the middle of the pistachio orchard with cover crops. (Greg Urquiaga/澳门六合彩开奖结果走势图)
澳门六合彩开奖结果走势图 postdoctoral student Anish Sopkata, left, and USDA research scientist Matt Roby adjust an eddy covariance flux tower, which measures the exchange of carbon dioxide gases and evapotranspiration in the pistachio orchard. (Gregory Urquiaga/澳门六合彩开奖结果走势图)

Farms typically emit more greenhouse gases than they store. But these cover crops could sequester some of the carbon.  Cover crops could also lessen groundwater overdraft. Growers can use water stored in the soil first and delay irrigation.

Cover crops aren鈥檛 a panacea for California鈥檚 groundwater woes. Kisekka said farmers may have to think twice about how cover crops could impact their water balance. While the Sacramento Valley, home to Bullseye and Westwind farms, receives an average of 17 to 18 inches of rainfall a year, the southern San Joaquin Valley averages only 7 inches of annual rainfall. Kisekka said growers could still plant cover crops but may have to terminate them early so they don鈥檛 compete for water with other crops.

Mallika Nocco, an assistant professor of Cooperative Extension in soil-plant-water relations, is studying whether a new cover crop called Oakville bluegrass might be better suited for the southern San Joaquin Valley.

鈥淚t鈥檚 been engineered for places like California, and it doesn鈥檛 need that much water so it鈥檚 not going to compete with a cash crop for water,鈥 she said. 鈥淚t鈥檚 a great example of a new solution for how a cover crop could work in a more arid climate.鈥

Using California farms to recharge aquifers

Climate change is expected to bring not only more intense drought but also more torrential downpours like California has had this winter. Harter and other colleagues at the 澳门六合彩开奖结果走势图 Agricultural Water Center are examining the benefits of funneling excess water to farmlands to recharge groundwater.

鈥淭he agricultural landscape is the largest place in California where we can do managed aquifer recharge,鈥 Harter said. 鈥淲e need to figure out how to do that recharge in a way that minimizes impacts to crops, but also in ways where we鈥檙e not sending agricultural fertilizer or pesticides down to groundwater.鈥

Significant hurdles exist. Not all soil will allow water to seep into the aquifer, and diverting water from rivers or creeks could unleash an environmental and water rights legal battle. California Gov. Gavin Newsom signed an this year that temporarily eased permitting requirements to divert water to farmlands for recharge.

Diverted water spills into an almond orchard in Modesto, CA in November of 2016 to help recharge the aquifer beneath the field. 澳门六合彩开奖结果走势图 scientists are studying managed aquifer recharge as a solution to California's groundwater overpumping. (Curtis Jerome Haynes)
Diverted water spills into an almond orchard in Modesto, California, in November of 2016 to help recharge the aquifer beneath the field. 澳门六合彩开奖结果走势图 scientists are studying managed aquifer recharge as a solution to California鈥檚 groundwater overpumping. (Curtis Jerome Haynes)

澳门六合彩开奖结果走势图 groundwater hydrologist Helen Dahlke, with the Department of Land, Air and Water Resources, told the that it鈥檚 a step in the right direction. The regulatory system, she said, should 鈥渟trike a balance between maintaining needed river flows for the environment and replenishing aquifers.鈥

Dahlke has examined how respond to floodwaters, to determine how best to recharge groundwater without waterlogging crops.    

Even if the state succeeds with managed aquifer recharge, Harter said California might only recover 20% to 40% of the groundwater lost every year, based on targets outlined in Newsom鈥檚 . Farms and communities will still need to use less.

Harter and Kisekka are optimistic about California鈥檚 resolve to achieve sustainable water use.

鈥淭he challenges are great,鈥 Kisekka said, 鈥渂ut also the advances in science and technology make me hopeful that we can continue to produce nutritious food that we all need while making sure we鈥檙e creating minimum impacts on the environment.鈥

 

Related Stories

 

Media Resources

Media Contact:

of images for download

Primary Category

Secondary Categories

Environment

Tags