April Leaf Sampling Protocol

To take and utilize an early season leaf sample for estimating of seasonal nitrogen needs, follow the UC Early Season Protocol (UC ESP) for leaf sampling (details below).  So far, this program has only been tested on Nonpareil, but it should work well for other varieties.  (Dr. Brown’s lab is working up the details for a Monterey variety sampling protocol.  For now, here’s how to take leaf samples using the new UC protocol worked up for Nonpareil:

April 16, 2013

Fertilizing Young Trees – First Year Trial Results

There have been several posts over the past few weeks about fertilizing mature almond trees. This data has been based upon long term studies held primarily in Kern County with some data points from across the state. Not all of this, however, is applicable to determining the rates of fertilization for developing almond orchards. At best, there are “educated guesses” in regards to identifying the proper rate for developing trees. Whole tree assays have found about 480 lbs of N/acre are stored within the woody biomass of mature trees. In order to reach that amount, trees would have to be accumulating nitrogen within the woody tissue at a rate of 20-50 lbs/acre/year until maturity (10-12th leaf). Once the tree begins to bear (~3rd/4th leaf), nutrients must be added to compensate for what is removed by the crop.

April 3, 2013

Nutrient Removal for Almond

I have received a few inquiries about the nutrients removed for almond. Based on Dr. Patrick Brown’s group’s work (Sebastian Saa Silva and others), the amount of NPK removed with every 1000 kernel pounds of almond is: Nitrogen – 65 lbs, Phosphorous – 8 lbs, and Potassium – 76 lbs. This includes the nutrients removed will all of the materials exported out of the orchard in a typical pick-up operation – hulls, sticks, leaves, shells, and kernels. Keep in mind that more than the above amounts may be needed to compensate for the inefficiencies of application and uptake (i.e. nitrogen uptake efficiency is somewhere between 75-85%, condition dependent — so to have 65 lbs of uptake, 76-85 lbs of N must be applied). As noted in the comments below, potassium and phosphorous must be converted to oxides. This can be done as follows: Almond removal 8lbs of P = 18.4lb of P2O5 76 lbs of K = 91.2 lbs of K2O For Phosphorus o Lbs. P x 2.3 = lbs. P2O5 o Lbs. P2O5 x 0.43 = lbs. P   For Potash o Lbs. K x 1.2 = lbs. K20 o Lbs. K20 x 0.83 = lbs. K

January 24, 2013

Broadcasting compost within Orchards

Compost spreaders are working in almond orchards in this area.  The addition of composted organic matter – often composted yard waste — to soil should generally benefit soil physical and chemical properties.  However, it isn’t a source of short-term plant available nitrogen.  Research by UC Davis specialists Tim Hartz and Jeff Mitchell has shown that composted yard waste, when mixed with sand and held under constant, optimum moisture and temperature (the optimum conditions for mineralization of organic nitrogen) produces a very little plant available nitrogen (2% of total nitrogen in the compost) in the short run (12-24 weeks).  When compost is broadcast on the soil surface and not incorporated, plant available nitrogen should be even less.  Dr. Hartz did conclude that manures and composts had value in long-term soil building in vegetable crop production, where those materials are incorporated into the soil.  [Untreated/uncomposted manure use in almonds is a food quality risk and not supported by the almond industry.] Why bring up compost use? Growers are willing to pay for it and seem happy with the results.  Here’s why.  If California agriculture ends up in a regulatory situation where nutrient budgets are required of growers, it should be recognized that the short term nitrogen benefits from composted yard waste are almost non-existent and the long term benefits are unknown. Previous entries on compost applications can be found here and here.

November 20, 2012

Fall Foliar Fertilizers: Targeted v/s General Approach

A PCA asking me the other day what I thought of a general micronutrient (iron + molybdenum + zinc + copper + manganese + boron +?) compared to a standard zinc + boron spray program that is common in postharvest almonds in the areas where I work. This question got me thinking about a review of fall fertilizer programs in general, with a focus on foliar nutrients. There are more than a dozen mineral nutrients essential for plant growth. However, only a handful of those nutrients have been shown to be important – in general — to profitable almond production. These

September 19, 2012

Summer leaf sampling is serious business

It’s July. Among key orchard activities as harvest approaches, it’s time to sample almond leaves for nutrient analysis. The lab analysis report for a leaf sample serves as part of the “report card” for your fertility program for this growing season for a particular variety in a particular block. A previous post from “The Almond Doctor” covers the practice of summer leaf sampling and shows the University of California critical nutrient levels for almond leaves sampled in July. This post will talk about several additional steps to orchard nutrition assessment in summer and to stress the importance of these practices to the commercial success of an orchard. Take separate leaf samples for each variety in a block. Crop load is the key factor determining mature almond tree nitrogen (N) and potassium (K) use. Different almond varieties in the same block can produce different yields and nutrient demand based on their genetic potential and conditions at bloom. If you don’t already, consider taking leaf samples for nutrient analysis from each variety. Use the lab reports and crop yield reports from each variety in the block from this year as background information when it comes time to apply N and/or K fertilizer for next year. If you applied the same amount of N and K fertilizer this season to all trees in an orchard, yet the Non-pareil yield was off and the Monterey yield was high, can you see that reflected in the leaf analysis reports? Variety specific leaf analysis and cropload data can help you understand how different varieties use expensive nutrients and how you might possibly fine tune your fertilizer delivery to optimize yield without wasting money.  Look up between leaf samples. Adequate tree vigor (growth) is key to good production. Adequate leaf nutrient levels and little to no growth

July 18, 2012

Some Thoughts on 2012 Bloom

To date, the weather has been very warm, with conditions favoring bee flight and pollination, but not the various bloom time diseases. The bloom looks strong across the county. In other words – so far, so good. I have received a few calls from a variety of topics, and will post some thoughts on these topics. Next week, there looks to be a few showers moving into the area, so fungicide coverage may be needed to prevent various diseases – especially if a fungicide application hasn’t been made. If an application has been made, it should provide protection for 10-14 days, dependent upon the amount of rain received. Delayed Varietal Bloom, Weak Bloom.I have received several calls regarding delayed bloom of Monterrey and Fritz. Although these thoughts are conjecture, discussions with a few advisors concluded that post-harvest tree conditions/ practices may be the cause for these issues. Tree conditions include defoliation of trees last fall from scab and rust, water stressed from a delayed harvest, and inadequate rainfall during the dormant period. Practices that may have encouraged this separation include delayed application of nitrogen and water during the post-harvest period, and missed pre-irrigations this past winter due to lack of water. Also consider that these trees have had high yields over the past few years – with two years of delayed harvests (mid-Sep-Oct) with Fritz/Monterrey. Many people have asked about inadequate chilling being a possible cause, but ample chilling has been received. More importantly, if it was a weather effect, we would expect to see the variations in bloom time occurring across a wide area – not just in a single orchard. For example, one orchard has had an issue with the delayed bloom, while the neighboring orchard with the same varieties is blooming as expected. Birds Eating Blossoms?Catching me a bit

February 24, 2012

Observations of Krymsk-86 Rootstock

Written By Joe Connell, UCCE Farm Advisor, Butte County Krymsk 86 is a peach-plum hybrid rootstock (Prunus persica x P. cerasifera) that originated in the Krasnodar region of Russia. As such, this hybrid rootstock is different than any other rootstock in use in the California almond industry. Now that it is planted in commercial orchards under many different conditions we are learning more about how it behaves when grafted to almond. When grafted to peach, plum, or apricot it is thought to be tolerant of cold temperatures, drought, water logging, resistant to phytophthora, and somewhat resistant to lesion nematodes. It was observed to be precocious, productive, and appeared to increase fruit size. Now that it is grafted to almond in California we are discovering that trees behave differently than almond grafted on peach rootstocks and differently than almond grafted on Marianna 2624 plum. In fact, it behaves uniquely like almond grafted on Krymsk 86. The first trial in Butte County including this rootstock was planted in 2003. Just completing their ninth growing season, the Nonpareil trees on Krymsk 86 are larger than adjacent trees on Lovell peach. What we know so far is that Krymsk 86 appears to be compatible with almond and it has a vigorous root system with good anchorage as a young tree. Krymsk 86 roots are susceptible to root knot nematodes and this will limit its usefulness in the San Joaquin Valley and on light textured soils where root knot can be a problem. In sandy soils in Stanislaus County, trees on Krymsk 86 are less vigorous than trees on peach roots. In spring 2011, soils were wet and cold for an extended period causing trees to get a slow start. Several young orchards had yellow trees showing up on Krymsk 86. Trees were yellow for

November 20, 2011

Compost Applications for the Almond Orchard

Compost is applied by many growers as a supplement to their nutrient management program. Composts may contain nitrogen, phosphorous, potassium, and other micro-nutrients. Applications of compost also add organic matter, and the associated organic acids, which has been shown to increase soil tilth in cropping systems.  Since all composts vary in nutrient content due to the variability in source material, nutrient benefits can only be determined through analysis. Nitrogen from Compost. To understand the effect of nitrogen from compost, we must first understand the nitrogen cycle. Organic matter contains nitrogen that is bound to various chemical compounds within the plant material. Termed organic nitrogen, it is unavailable to the plant. It can only be made available to the plant upon mineralization and conversion to nitrate through the process of nitrification. These processes are mediated by the soil microbial community. Once converted to nitrate, the nitrogen is available for plant use. Synthetic fertilizers go through similar processes depending upon their starting point (i.e. ammonium, nitrate, etc.). Figure source: www.physicalgeography.net/fundamentals/9s.html Most finished composts vary from 0.5-2.5% total nitrogen. Since most of the nitrogen is held within plant compounds (organic form), not all of the nitrogen will be mineralized and available upon application. Research by Dr. Tim Hartz, UC Davis, has shown that most composts only release about 5-10% of the nitrogen in the nitrate form. Composts that have a lower carbon to nitrogen ratio release nitrate on the higher end of this range. Higher nitrogen containing composts (> 3% nitrogen) may release more than 10% of the nitrogen. Nitrogen benefits from compost also appear to be reduced in the following growing seasons, with very little mineralization occurring. At this point, it appears that the compost is simply organic matter. Phosphorus from Compost. Phosphorous (P) content within compost can be significant. Since exportation of

November 6, 2011

Compost Quality: What the Analysis Reveals

Compost is applied by many growers as a supplement to their nutrient management program. Adding organic matter and the associated organic acids, has been shown to increase soil tilth in cropping systems. All composts vary in nutrient content, which is heavily dependent upon the source material of the compost. Since sources vary, it is important to have an analysis in order to determine nutrient content. To understand how compost works, we must first understand the nitrogen cycle. Organic matter contains nitrogen that is bound to various chemical compounds within the plant material. Termed organic nitrogen, it is unavailable to the plant. It can only be made available to the plant upon mineralization and conversion to nitrate through the process of nitrification. These processes are mediated by the soil microbial community. Once converted to nitrate, the nitrogen is available for plant use. Synthetic fertilizers go through similar processes depending upon their starting point (i.e. ammonium, nitrate, etc.). Nitrogen from Compost.Most finish composts vary from 0.5-2.5% total nitrogen. Since most of the nitrogen is held within plant compounds (organic form), not all of the nitrogen will be available upon application. Research by Dr. Tim Hartz, UC Davis, has shown that most composts only release about 5-10% of the nitrogen. Composts that have a lower carbon to nitrogen ration release on the higher end of this range.Higher nitrogen containing composts (>3% nitrogen) may release more than 10% of the nitrogen.. Nitrogen benefits from compost also appear to be reduced in the following growing seasons, with very little mineralization occurring. At this point, it appears that the compost is simply organic matter. Phosphorous from Compost.Phosphorous (P) content within compost can be significant. Since exportation of P from the almond orchard is low (7 lbs/1000 kernel lbs), attention should paid to prevent over application of P. P is

November 5, 2011