- Author: Mark Bolda
- Author: Tim Hartz
The question has come up more than a few times from industry participants on how to adjust nitrogen (N) inputs for strawberry varieties more productive and of larger plant size than Albion for which the original DRIS study was done.
Simple math says one could just increase simply N uptake estimate to cover the added fruit and bigger plant, so if Monterey produces 20% more fruit, and is that much larger a plant, one just adds 20% more nitrogen to the standard annual fertility program to make up the difference. However, as simple as this math may seem, it could quite possibly be incorrect, since it is not at all unknown that different strawberry varieties have variations in N content in the fruit and leaves.
The work to determine N content of Monterey compared to that of Albion was done over two samplings (one in early May, the other mid-July) of five fields of Albion and five fields of Monterey. We found that Monterey had marginally higher N concentrations in both the leaves (Table 1) and the fruit (Table 2) on both sample dates. An evaluation of plant size, without fruit, found that Monterey also ran about 20% larger than Albion from the five fields sampled.
From this information, we can say that N uptake is at least as high in Monterey as in Albion per unit of plant growth. That is to say, if a grower expects and has experienced 20-25% increases in fruit yield with Monterey over that of Albion, then the amount of N uptake to support that level of productivity will also be 20-25% higher than for Albion.
We need to be careful here however. This is not a call for growers of Monterey to automatically increase their N fertilizer additions by 25%. If a grower is finding his or her seasonal practices in the lower half of typical grower practice, then an increase in nitrogen application could be tested, but if a grower is already using a lot of N, say above 250 lbs per acre, then that might be enough to absorb the higher N requirement of Monterey.
Table 1: Nitrogen (N) concentrations in dry leaves
Variety |
4-5 May |
12-15 July |
Monterey |
3.02 % |
2.71 % |
Albion |
2.81 % |
2.44 % |
Table 2: Nitrogen (N) concentrations in dried fruit
Variety |
4-5 May |
12-15 July |
Monterey |
1.28 % |
1.06 % |
Albion |
1.22 % |
0.93 % |
Many thanks to the growers who participated in this study, and generously allowed me to tear plants out of their fields for the plant size sampling.
- Author: Michael D Cahn, Ph.D.
Tomorrow we will host the 2016 UC Irrigation and Nutrient Meeting at the Agricultural Center in Salinas CA. We also have a field meeting following a pizza lunch to discuss the use of cover crops in strawberries. 4.5 hours of Certified Crop Adviser educational credits will also be available. This year we will include a panel discussion about how growers are implementing practices to better manage water and nitrogen fertilizer as well as a presentation on the sustainable groundwater management act. Please see the agenda below:
2016 Irrigation and Nutrient Management Meeting
Agricultural Center 1432 Abbott Street, Salinas, CA
Wednesday, February 17
7:45 a.m. to 1:45 p.m.
4.5 CCA Credits applied for
7:45 Registration
8:00 Summary of N use of crops in Region 3 and current water quality regulations
Chris Rose, Central Coast Regional Water Quality Control Board
8:30 Fertilizer value of N in irrigation water
Michael Cahn, Irrigation and Water Resources Farm Advisor, Monterey County
9:00 Field studies on N and water management (broccoli and spinach)
Richard Smith, Vegetable Crops Farm Advisor, Monterey County
9:30 Denitrification beds for removing nitrate from tile water
Tim Hartz, Vegetable Specialist, UCD
10:00 Break
10:30 Potential for increasing groundwater recharge on agricultural land
Toby O'Geen, Soil Specialist, Dept of Land, Air and Water Resources, UCD
11:00 Groundwater Sustainability Act – Where are we headed in Monterey County
Stephanie Hastings: Brownstein, Hyatt, Farber and Schreck Law Firm
11:30 Panel discussion on Grower implementation of BMP's
Salvador Montes, Christensen and Giannini; Manual Mercado, River Valley Farms;
Eric Morgan, Morgan Consulting
12:00 Conclusion and Pizza Lunch
Afternoon Session:
12:45 Field trip to see conservation practices
1:45 Conclusion
- Author: Ben Faber
Silicon is currently under consideration for elevation to the status of a "plant beneficial substance by the Association of American Plant Food Control Officials (AAPFCO). Silicon has been shown in university and field studies to improve cell wall strength and structural integrity, improve drought and frost resistance, decrease lodging potential and boost the plant's natural pest and disease fighting systems. Silicon has also been shown to improve plant vigor and physiology by improving root mass and density, and increasing above ground plant biomass and crop yields.
Silicon (Si) is the most abundant element (27.2%) present in the earth's crust following oxygen (45.5%). Silicon is known for a number of important chemical and physical properties, i.e. semiconductor property that are used in various scientific and technical applications. In most soils near a neutral pH, the composition is a complex of iron, aluminum, oxygen and silicon. Silicon is one of the most important constituents of dust, which is carried by winds all over the world. Geologists know silicon as the rock quartz and the many silicate materials, such as opal. Formally, silica (SiO2) is a silicic acid (H4SiO4), which is water soluble and stable in highly dilute aqueous solutions. There are many forms that silicon can take in the natural environment, often complexed with water. Plants take up a form of silicic acid and in highly leached, low pH environments, much of the silicon may have been removed over time.
It appears that grains, such as wheat and especially rice have an absolute need of supplemental silicon to improve plant growth. Few non-grass plants have shown this need other than cucurbits apparently. Much of the improvement typically is for improved disease control and improved stature (prevention of lodging).
Many of the studies showing benefits of silicon amendment have occurred in low soil pH environments or in solution culture where it has been possible to create low silicon growing media. Several years ago, potassium silicate was being promoted as a fungistat for controlling Phytophthora root rot in avocado. A number of field and greenhouse trials were tried in California during the early 2000s to assay its effect. For whatever reason, the material showed no effect on the disease. Potassium and calcium silicates are liming materials, raising soil pH. The effect that was noticed in its use in other countries may simply have been a soil pH effect on either the avocado tree, the Phytophthora or both.
- Author: Michael D Cahn
If you missed the 2015 Irrigation and Nutrient Meeting or you would like to review the presentations, you can download pdf versions of the powerpoint files from the UCCE Monterey County Website (http://cemonterey.ucanr.edu). The direct link to the presentations is:
http://cemonterey.ucanr.edu/Vegetable_Crops/2015_Irrigation_-_Nutrient_Management_Meeting_
We want to thank all of you who attended for your participation and for the many constructive comments that we received verbally and through the evaluation surveys. Let us know of any topics that you would like us to address in the next irrigation and nutrient management meeting or ways to improve the meeting.
If you are interested to learn more about CropManage for improving irrigation and nutrient management, I plan to host a hands-on training on using this on-line decision support tool on April 2nd. I will send out a formal announcement in the upcoming weeks.
- Author: Cheryl A Potts
In my last blog, I talked about my struggle with the chemistry, the science of gardening, the bones that make it all work--not my forte. However, I decided to face it as a mature gardening adult, and learn, for starters, my N-P-Ks, those three mysterious numbers found on boxes of fertilizers and bottles of plant food. As I mentioned in my last blog (May 1), the first number listed stands for nitrogen, "N", which is essential for for healthy leaf growth. I discussed what your plants might look like if they were nitrogen deficient, and some suggestions to solve the problem.
Now we come to the second number, which informs the user of the percentage of phosphorus, "P", contained in the product inside.
I have been told (by a former science teacher, no less) that phosphorus has been used since WWI up through present day wars as a smoke tracer, an explosive, a poison and nerve gas, and has been called "the Devil's element". So why would I want this destroyer of life in my benign veggie garden? Well, it turns out that phosphorus comes in many forms and colors. It actually takes up 1 % of each one of our body weights, and is found in each cell of the human body without smoking or poisoning. It's primary use in our body, unlike in Vietnam, is the formation of bones and teeth. And just to prove to you phosphorus' versatility, it is the primary ingredient found on the head of a safety match. Believe me, this is all very confusing to a science dropout.
Phosphorus was actually discovered by a man from Munich, Germany named Hennig Brand in 1669, who found it while experimenting with urine, producing a product that actually gave off a pale green glow. He kept his method secret, as he, along with all alchemists of the day, was planning on turning his discovery into gold. He finally agreed to share his formula, and gardening has never been the same since.
But back to the question as to why any of us would want phosphorus in our gardens. Phosphorus is actually a mineral that is essential to metabolism. It is the principal element in the structure of the nucleus and cytoplasm of all tissue cells. Without it, as with nitrogen, plants do not thrive. Phosphorus is instrumental in aiding a plant convert needed nutrients into the useable building blocks that it needs to grow. If your plants are spindly, stunted in growth, have leaves that are blue/green with a purplish tinge, produce small fruit with an acid taste, or set very little fruit at all, you most likely have a phosphorus deficiency. Plants that are especially susceptible to this deficiency are carrots, lettuce, spinach, apples, currents, and gooseberries. The purplish tinge seen on the underside of tomato leaves indicates a "P" problem.
These deficiencies occur primarily in areas where there is a high level of rainfall, especially if the soil is acidic, clay, or poor chalk. Cold weather can also be a factor in the poor absorption of phosphorus.
The remedy is simple. Add organic material such as fish fertilizer as a soil drench, bone meal, colloidal phosphate or compost (food wastes are quite high in phosphorous). Also, the addition of rock phosphate is highly recommended. Edward C. Smith, author of The Vegetable Gardener's Bible, states that as phosphorus is most likely to be the nutrient missing from the soil, adding rock phosphate whenever you start a new garden is a wise move. He recommends 10 pounds per 100 square feet. Be forewarned, however. Plants that naturally adapt to low levels of available phosphate are more likely to suffer from phosphate poisoning. Aha! Back to a war reference.
Mr. Smith also makes another interesting point; do not be misled when you read numbers on the package of rock phosphate (0-4-0) that its phosphate contents is only 4%. That 4% represents the immediate available phosphorus. The product actually is about 30% phosphorus with more than 25% of it in a slow release that will become available over time.
We have one more letter to explore in our nutrient alphabet, and in my next blog I will discuss that third label number. Mmmmmm. Could "K" stand for "Kompost"?