Posts Tagged: nitrogen
Every little bit helps, and the Ventura County Resource Conservation District might help some Ventura growers.
The Ventura County Resource Conservation District (VCRCD) would like to remind agricultural producers about an existing incentives program, the Calleguas Creek Watershed Agricultural Management Measures Program (CCWAMMP). The purpose of CCWAMMP is to improve water quality in the Frontal Pacific and Revolon Slough subwatersheds of Calleguas Creek. To achieve this, VCRCD, with funding from the State Water Resources Control Board, will reimburse growers a portion of the costs needed to implement certain agricultural management measures (MMs) and irrigation efficiency upgrades. If you are a grower in the coastal region of the Calleguas Creek Watershed, please submit an on-line CCWAMMP Interest Survey to VCRCD today! The CCWAMMP interest form is available here.
VCRCD is also pleased to announce that a new incentives program, Interactive Irrigation Management to Reduce the Leaching of Nitrogen (MRLN), is expected to start April 2020. The goal of the MRLN program is to help agricultural producers build irrigation and fertilizer schedules that reduce the potential for nitrogen leaching. To achieve this goal, VCRCD will provide participants incentives for lysimeters and soil moisture sensing equipment as well as free irrigation and nutrient management technical assistance. Specifically, VCRCD will work with the landowner and agronomy professionals (such as Cooperative Extension staff) to evaluate the lysimeter and soil moisture data and provide the participating landowner guidance concerning potential irrigation and fertilization improvements. If you are near a nitrogen-impacted waterway in Ventura County, please submit a MRLN interest form here.
For more information about either of these programs, please contact Jamie Whiteford at email@example.com.
California growers can download a new series of publications summarizing efficient nitrogen management practices from UC Agriculture and Natural Resources. The publications are designed to assist growers in complying with state regulations for tracking and reporting nitrogen fertilizer applied to crops, in an effort to prevent nitrogen from leaching into groundwater.
The science-based publications are associated with a series of trainings for growers and Certified Crop Advisers to develop efficient nitrogen management practices, an effort coordinated by UC ANR's California Institute for Water Resources.
“Our role is to provide farmers, agricultural consultants and policymakers the best science possible for making decisions on managing and protecting California groundwater,” said Doug Parker, director of the water institute.
The free publications, created from training materials, lessons learned from the training sessions and from additional UC research, can be downloaded at http://ucanr.edu/nmgmtpublications.
The following publications are now available for download:
· Principles of Nitrogen Cycling and Management
· Irrigation and Nitrogen Management
· Nitrogen Management for Nut Crops
· Nitrogen Management for Deciduous Fruit and Grapes
· Nitrogen Management for Citrus and Avocado
· Nitrogen Management for Cool-Season Vegetables
· Nitrogen Management for Strawberry Production
· Nitrogen Management for Processing Tomato
· Nitrogen Management for Corn on California Dairies
The publications were authored by Parker of California Institute for Water Resources; Patrick Brown, professor in the UC Davis Department of Plant Sciences; Allan Fulton, UC Cooperative Extension advisor, Tehama County; Tim Hartz, UC Cooperative Extension specialist emeritus, UC Davis Department of Plant Sciences; Dan Munk, UC Cooperative Extension advisor, Fresno County; Daniel Geisseler, UC Cooperative Extension specialist, UC Davis Department of Land, Air & Water Resources; Michael Cahn, UC Cooperative Extension advisor, Monterey, Santa Cruz and San Benito counties; Richard Smith, UC Cooperative Extension advisor, Monterey, Santa Cruz and San Benito counties; Marsha Campbell, UC Cooperative Extension advisor emeritus, Stanislaus County; Sat Darshan Khalsa, UC Davis project scientist; and Saiful Muhammad, UC Davis graduate student.
Developed in 2014, the training program has been offered at 11 different locations around the state, most recently in Fresno. More than 1,000 Certified Crop Advisers have taken the training.
The nitrogen management training curriculum was developed by a group of UC ANR faculty, specialists and advisors. The first day focuses on the nitrogen cycle in crop production systems, nitrogen sources, irrigation and nitrogen management, and nitrogen budgeting. The second morning covers annual and permanent crops and nitrogen planning practices.
For more information on the nitrogen management training materials, visit http://ciwr.ucanr.edu/NitrogenManagement.
The Nitrogen Management Training and Certification Program is a joint effort between the California Department of Food and Agriculture, UC Agriculture and Natural Resources, California Association of Pest Control Advisers' Certified Crop Adviser Program and the Regional Water Boards.
“Wood chip mulches will decrease soil nitrogen and spread pathogens” A Misunderstanding that is addressed below by:
Chalker-Scott, L. , Extension Specialist And Associate Professor, Washington State University
Downer, A.J., Farm Advisor, University of California
With chronic drought and/or record-breaking summer temperatures making it increasingly important to conserve water, many gardeners and groundkeepers are using landscape mulches. The ideal landscape mulch not only moderates soil temperature and conserves water, but also:
- reduces compaction;
- provides nutrients;
- enhances plant growth;
- provides habitat for beneficial insects;
- helps control weeds, pests and disease; and
- reduces the need for pesticides and fertilizers.
In addition, landscape mulches should be readily available, affordable, and easy to apply and replace. A review of the literature on landscape mulches (Chalker-Scott, 2007) determined that organic mulches are overall the best choice, with deep layers of coarse woody material providing most or all of the above-listed benefits. Arborist wood chips (created from leaves and branches chipped up by tree service companies) are a particularly good option as they are generally inexpensive and easy to obtain anywhere trees are managed.
Fortunately, none of these concerns are validated by research. Here are some brief explanations (Chalker-Scott, 2007) targeted to our audience:
- Wood chips will not draw nitrogen from the soil unless they are incorporated into it. When used as mulch, arborist chips have no effect on underlying soil nitrogen levels, except to increase them over time.
- Wood chip mulches, even those made from diseased trees, will not transmit pathogens to healthy plant roots. If diseased chips are incorporated into the soil they could infect plant roots, but field evidence of this is rare. Arborist chips that are stockpiled even for a few days undergo severe pathogen reduction through microbial attack within the pile (Downer et al., 2008).
- Wood chips, or any other organic mulch, will not change the pH of the soil. The soil volume is vast, and any acidification would occur only at the mulch-soil interface where it would quickly be neutralized.
- Wood chips, even those made from black walnut or cedar, will not kill landscape plants. There is no reliable evidence that chemical inhibition from decaying wood actually occurs in a landscape situation.
- Wood chip mulches do not lend themselves to tunnel building like landscape fabric and other sheet mulches do: they collapse. Termites do not eat wood chips unless they have no choice; they are negatively affected by some of the chemicals wood contains. In fact, arborist chip mulches house a number of beneficial insects and other species that naturally control pests.
For arborist wood chip mulches to be the most effective (Chalker-Scott, 2007), they should be:
- coarse – no less than ½” diameter – so water and air can move freely through them;
- applied as soon as possible after chipping both to maximize the materials available to microbes and to capture the nutrients released by their activity in the soil; and
- maintained at a depth of at least 4” to prevent weed growth.
Part of my work has come to include substrate production of caneberries. Some of these are easy since they are pest management issues which don't vary that much from field problems, but others, like the nutritional situation depicted below, are far more complex.
A couple of things going on in this field, which are raspberries being grown in substrate under macro-tunnels. First, the very young leaves have a light yellow cast (see photo one below) to them and second the older leaves are seeming to have some difficulty (see second picture below), again becoming a sterner sort of yellow. I don't worry as much about the older leaves as I do the newer ones, which after all represent the future of the plant.
As you know, I'm not making any call without doing some thorough sampling. In this case, we took multiple samples of the younger leaves demonstrating the lighter shade of yellow and the same for the older yellowed leaves. To set the baseline, adult normal leaves (those surrounding the yellow leaves in the first picture below) were also sampled in multiple.
An important comment. We are sampling leaves of 3 different ages, and we should be aware that this is going to distort some of the concentrations. For example N, P, and K as plant mobile will by default trend higher in younger leaves, and nutrients such as Ca and B are going to trend higher in the older.
And sure enough in perusing the analysis below, N,P and K are higher in our newest leaves and lowest in the older, with the adult leaves in between. Likewise, Ca and B are very much higher in the oldest leaves than the other two age leaves, and as a matter of fact in the newest leaves these two nutrients are lower than what one normally would see recommended.
|Mineral||Adult normal leaf||New, yellow||Old, yellow|
Moving on however to the levels of iron things get a bit more interesting. While it is highly accumulated in the oldest leaves, it is far less so in the youngest at 4x less, and 3x in the normal adult leaves. Calcium shows a similar pattern of concentration, but the visual symptoms are nothing like what we know calcium deficiency to look like. Iron deficiency, on the other hand, usually described as chlorosis of one type of another, as a matter of fact does. In addition, we know that nitrogen can accentuate iron deficiencies because of growth promotion.
The older leaves turning yellow? It seems to me they are just old leaves, might be some dieback being pushed by high tunnel heat but nothing that excites a lot of attention.
In other words, it looks like the plant is outgrowing its ability to pull up iron for the moment. Given that we've had (still in October of all things!) some pretty hot plant growth weather, once the weather cools down a lot of this should disappear.
My advice to the grower is watch this one, I'm not sure yet concrete action is merited yet, best to see if once the plant slows down in its growth and nitrogen accumulation these symptoms subside.
Note the contrast of these newer leaves to the midtier leaves around them. Not an plant mobile nutrient, like NPK, so what could be the issue?
On the other hand, many of the very oldest leaves were showing these symptoms, which look a lot like heat or salt damage.
For centuries, the prevailing science has indicated that all of the nitrogen on Earth available to plants comes from the atmosphere. But a study from the University of California, Davis, indicates that more than a quarter comes from Earth's bedrock.
The study, to be published April 6 in the journal Science, found that up to 26 percent of the nitrogen in natural ecosystems is sourced from rocks, with the remaining fraction from the atmosphere.
Before this study, the input of this nitrogen to the global land system was unknown. The discovery could greatly improve climate change projections, which rely on understanding the carbon cycle. This newly identified source of nitrogen could also feed the carbon cycle on land, allowing ecosystems to pull more emissions out of the atmosphere, the authors said.
"Our study shows that nitrogen weathering is a globally significant source of nutrition to soils and ecosystems worldwide," said co-lead author Ben Houlton, a professor in the UC Davis Department of Land, Air and Water Resources and director of the UC Davis Muir Institute. "This runs counter the centuries-long paradigm that has laid the foundation for the environmental sciences. We think that this nitrogen may allow forests and grasslands to sequester more fossil fuel CO2 emissions than previously thought."
WEATHERING IS KEY
Ecosystems need nitrogen and other nutrients to absorb carbon dioxide pollution, and there is a limited amount of it available from plants and soils. If a large amount of nitrogen comes from rocks, it helps explain how natural ecosystems like boreal forests are capable of taking up high levels of carbon dioxide.
But not just any rock can leach nitrogen. Rock nitrogen availability is determined by weathering, which can be physical, such as through tectonic movement, or chemical, such as when minerals react with rainwater.
That's primarily why rock nitrogen weathering varies across regions and landscapes. The study said that large areas of Africa are devoid of nitrogen-rich bedrock while northern latitudes have some of the highest levels of rock nitrogen weathering. Mountainous regions like the Himalayas and Andes are estimated to be significant sources of rock nitrogen weathering, similar to those regions' importance to global weathering rates and climate. Grasslands, tundra, deserts and woodlands also experience sizable rates of rock nitrogen weathering.
GEOLOGY AND CARBON SEQUESTRATION
Mapping nutrient profiles in rocks to their potential for carbon uptake could help drive conservation considerations. Areas with higher levels of rock nitrogen weathering may be able to sequester more carbon.
"Geology might have a huge control over which systems can take up carbon dioxide and which ones don't," Houlton said. "When thinking about carbon sequestration, the geology of the planet can help guide our decisions about what we're conserving."
The work also elucidates the "case of the missing nitrogen." For decades, scientists have recognized that more nitrogen accumulates in soils and plants than can be explained by the atmosphere alone, but they could not pinpoint what was missing.
"We show that the paradox of nitrogen is written in stone," said co-leading author Scott Morford, a UC Davis graduate student at the time of the study. "There's enough nitrogen in the rocks, and it breaks down fast enough to explain the cases where there has been this mysterious gap."
In previous work, the research team analyzed samples of ancient rock collected from the Klamath Mountains of Northern California to find that the rocks and surrounding trees there held large amounts of nitrogen. With the current study, the authors built on that work, analyzing the planet's nitrogen balance, geochemical proxies and building a spatial nitrogen weathering model to assess rock nitrogen availability on a global scale.
The researchers say the work does not hold immediate implications for farmers and gardeners, who greatly rely on nitrogen in natural and synthetic forms to grow food. Past work has indicated that some background nitrate in groundwater can be traced back to rock sources, but further research is needed to better understand how much.
"These results are going to require rewriting the textbooks," said Kendra McLauchlan, program director in the National Science Foundation's Division of Environmental Biology, which co-funded the research. "While there were hints that plants could use rock-derived nitrogen, this discovery shatters the paradigm that the ultimate source of available nitrogen is the atmosphere. Nitrogen is both the most important limiting nutrient on Earth and a dangerous pollutant, so it is important to understand the natural controls on its supply and demand. Humanity currently depends on atmospheric nitrogen to produce enough fertilizer to maintain world food supply. A discovery of this magnitude will open up a new era of research on this essential nutrient."
UC Davis Professor Randy Dahlgren in the Department of Land, Air and Water Resources co-authored the study.
The study was funded by the National Science Foundation's Division of Earth Sciences and its Division of Environmental Biology, as well as the Andrew W. Mellon Foundation.
Photo: The stuff that makes leaves green