Good chill hours are no assurance of pistachio crop size
Chill accumulation is only one contributor to bloom
Most pistachio-growing regions in California received enough chill hours this past winter to facilitate the set of the 2016 crop, says Elizabeth Fichtner, University of California Cooperative Extension (UCCE) farm advisor in Tulare County. This should come as good news to growers who last year saw their crop drop, due to poor winter chill along with warm and sunny days, and tight water supplies, to its smallest production since 2006 when acreage was half that of 2015. The average yield of 1,161 pounds per acre was the lowest since 1989. In an interview, Fichtner offered the disclaimer that one of the models for calculating chill is just that. She said, “It’s a model, not a law of nature,” meaning reaching some magic numbers – or not doing so - is not an assurance of crop size. Chill accumulation is only one factor contributing to bloom, she said. Fichtner wrote an article on expected pistachio bloom as an exercise in reviewing chill hour models. “I’m not a plant physiologist by training,” she said. “It gave me a better understanding of pistachio phenology.” A key source for her article is a chilling hour calculator on the UC Fruit and Nut Research and Information Center website at www.fruitandnuts.ucdavis.edu. There, growers can see the cumulative chilling hours for the current year plus historical data. The Peters male pistachio variety requires at least 900 hours below 45 degrees to achieve 50 percent bloom. The Kerman female variety requires 700 hours below 45 degrees to achieve 44 percent bloom. Among those production areas that fell short of 900 hours this winter were Davis and Coalinga at 796 and 878 respectively, Fichtner said. She said in 1978 “during the infancy of the California pistachio industry” the Davis area had a then-record low accumulation of winter chill at 670 hours. Last year, Davis experienced only 537 chilling hours. “The 200 to 300 acres of Kerman pistachios in Yolo County (home to Davis) may fall short of the chill accumulation for pistachios in 2016,” Fichtner said. On the positive side, she pointed out that Kern County’s Arvin area accumulated 904 chilling hours in 2015-2016. The early winter had 535 chilling hours. In Delano, 983 and 1307 chilling hours were accumulated in 2014-2015 and 2015-2016 respectively. Other areas which who fell short of the 900 number for 2015-2016 included Kettleman in Kings County at 856 and Tracy in San Joaquin County at 836. The chill accumulation data is generally derived from CIMIS (California Irrigation Management Information System) stations. Fichtner said there can be gaps in data due to station malfunctions, in some cases resulting from vandalism. “Because the purpose of CIMIS stations is to provide data for irrigation management, maintenance may be delayed in the winter months when the stations are not utilized for the intended purpose,” she said. Moreover, she points out, CIMIS stations capture data in specific locations and do not capture the variances of chill accumulation over some regions or in microclimates. Fichtner credited assistance from other UC researchers including Craig Kallsen, Louise Ferguson, Dan Parfitt, and Katherine Pope for helping her delve into the subject of pistachio bloom and chill hours. At a Pistachio Day event in Visalia, Ferguson explained that researchers are taking a closer look at the subject of chilling and two models for measurement. In addition to the 900-hour model that gauges chill between Nov. 1 and Feb. 28, another arrives at “chill portions.” The latter uses a weighted approach for temperatures between 33 and 55 degrees during the same period. With this model, intermittent warm temperatures reverse chill accumulation. Fichtner said chilling requirements for new female pistachio varieties including Golden Hills and Lost Hills have yet to be assessed, and she would like to study that further. The male pollinator for those two varieties is the Randy variety. At this year’s Pistachio Day, Kallsen discussed efforts to introduce from the UC breeding program an additional male pollinizer for Kerman, plus a new early-harvesting female and its male pollinizer. Another Pistachio Day speaker, UC Davis plant scientist Maciej Zwieniecki, said pistachio trees’ use of carbohydrates could have some interplay with chill factors. He called carbohydrates the trees’ “liquid assets” and characterized soluble carbs as “the cash the tree uses to pay for services. Starches are the savings account the tree draws from when cash is short.” Zwieniecki said temperatures figure into the balance between starch and sugar.
EU scientists begin review of ban on
pesticides linked to bee declines
EU scientists begin review of ban on pesticides linked to bee declines. In a letter to the European commission last month, which the Guardian has seen, the EU scientists said that they would finish their risk evaluation by the end of January 2017. A formal announcement that the review is underway is due imminently but a commission spokesman told the Guardian that it would not necessarily lead to any changes to the law. The restrictions on the use of neonicotinoids remain in place while this review is carried out,” he said. “Depending on the outcome of this evaluation, the commission will propose, only if justified, to further modify the conditions of approval of the three neonicotinoids. The expert panel could choose to tighten, as well as soften, the current ban on the use of thiamethoxam, clothianidin and imidacloprid, which was introduced following an Efsa ruling in 2012 that they posed an “unacceptable” danger to bees. That was seen as one of the hardest won environmental victories of the last commission. The issue pitted over 2 million environmental petitioners against pesticide manufacturers such as Bayer Crop Science, which condemned the ban as “draconian” and a drag on competitiveness. That was seen as one of the hardest won environmental victories of the last commission. The issue pitted over 2 million environmental petitioners against pesticide manufacturers such as Bayer Crop Science, which condemned the ban as “draconian” and a drag on competitiveness. The ‘neonics’ are thought to affect parts of the bee’s brain where sensory information related to orientation is stored. Scientists fear that exposure to even low doses of the substances could confuse bees, making it harder for them to find good sources of nutrition or safely return home to their hives. Greenpeace said it was optimistic that the new Efsa review would confirm its earlier assessment, partly because the authority would be using the latest risk assessment standards. “These require more testing and distinguish between different types of bees, like honeybees and bumblebees,” said Franziska Achterberg, Greenpeace EU’s food policy director. “The pesticides industry has lobbied hard for these standards to be rejected. But the EU has a legal mandate to protect bees from harmful pesticides, and a solid risk assessment is the basis for that.” Pesticides manufacturers such as Syngenta have argued that the Efsa guidance document, which is not used by all the EU’s member states, obliges a statistically untenable demonstration of safety. “It requires the ability to detect a 7% effect on honeybee colonies, which is below the natural variability you would see,” Peter Campbell, Syngenta’s senior environmental specialist said earlier this year. Europe’s pollinators are estimated to be worth €22bn (£16bn) a year, but one in six of them died off between 1985 and 2005 – with greater declines recorded in the UK, Germany and Sweden. The spectre of extinction now hangs over more than a quarter of Europe’s bumblebees and one in 10 of all honeybees, according to the International Union for the Conservation of Nature.
Water crisis in Iran: A desperate call for action
By Kaveh Madani
Drying lakes and rivers, declining groundwater resources, land subsidence, water contamination, water supply rationing and disruptions, forced migration, agricultural losses, salt and sand storms, and ecosystem damages are the modern water-related issues of a nation which was once recognized as the pioneer of sustainable water management. The government blames the current crisis on the changing climate, frequent droughts, and international sanctions, believing that water shortages are periodic. However, the dramatic water security issues of Iran are rooted in decades of disintegrated planning and managerial myopia. Iran has suffered from a symptom-based management paradigm, which mainly focuses on curing the problem symptoms rather than addressing the main causes. The separation of “development” from “environment”, and aggressive shortsighted regional development plans have resulted in unintended water problems whose long-term costs are significantly higher than their short-term benefits. No matter how advanced the Iranian water management system is in comparison with the other countries in the region, there is no doubt that Iran is currently experiencing a serious water crisis. In theory, Iran is currently experiencing the growth and underinvestment problems that the West experienced in the 20th century or even today. However, what makes the current problems in Iran different from similar problems in the West is the depth and extent of the secondary impacts of development. Rather than proactive management to prevent water problems, Iran’s reactive management has focused on curing the symptoms, whereas the causes of the problems are becoming worse over time. While the public, experts and media continuously warn about the major water crisis symptoms, less is being said about the main drivers of the crisis and effective exist strategies. But, what are the main drivers? Crisis driver 1: Population growth and spatial distribution. Crisis driver 2: Inefficient agriculture. Crisis driver 3: Mismanagement and thirst for development. What to do? The water problems in Iran are far too many and significant to leave any doubt about the fact that Iran is experiencing a looming water crisis. Immediate mitigation actions are required to address the existing water problems throughout the country. There are good signs that the new government of Iran recognizes water security as a national priority at the moment and is trying to address some of the more evident water problems immediately. Nevertheless, fundamental changes in the current Iranian water management paradigm are essential to prevent the development of similar problems in the future and to secure sustainable water resources for Iran.
Early pistachio nut count good news for Arizona’s Steve Seplak
Greg Northcutt, Contributing Writer
The 2016 pistachio season began early for Arizona grower Steve Seplak when his 20-acre SAS-Z Nuts pistachio orchard near Willcox, Ariz. began blooming in the first few days of March - three weeks earlier than usual. Aided by warm days with temperatures typically reaching into the mid-to-high 60s, most of the shells formed by the end of May. His trees planted 23-24 years ago produce an average of about 2,500 pounds of in-shell nuts annually. However, by mid-May, the nut numbers on Seplak’s trees suggested this on-year crop could surpass that figure. “We’re probably looking at potential yields of 2,800-3,000 pounds per acre this season,” the Cochise County grower says. This would be much higher than Seplak harvested last year when a hard pre-bloom freeze in late March and early April knocked tree growth back significantly. “We shook the trees twice at harvest but only about 14,000 pounds of nuts on the entire 20-acre orchard dropped. The rest remained on the trees,” he said. “Production just barely covered the bills. It was like that in pistachio orchards throughout the valley.” However, the smaller yields had a bright spot. The nuts Seplak gleaned last year fetched a record high $4 per pound in-shell – or 50 cents more than for his 2014 pistachio crop. Seplak is a member of the American Pistachio Growers’ board of directors, and the former president of the Arizona Pistachio Association. As of mid-May, his tress had received less than an inch of rain since the first of the year. Typically, rainfall during this period totals around 3½ inches. Seplak pumps groundwater for his micro-sprinkler irrigation system from a depth of 483 feet at the rate of 135 gallons per minute. “Our water table has stayed pretty stable over the past 14 or so years that I’ve been farming here, but it hasn’t risen any,” he says. To compensate for low soil levels of boron, copper, and zinc, Seplak fertilizes the trees with these nutrients several times a year in the irrigation water. Rates are based on results of an early spring leaf analysis. His first application this year was in early May. He typically applies the materials three times during the season. Dry weather this spring may have contributed to an earlier-than-usual appearance of aphids in his orchard in early May, Seplak noted. He treated the trees with an insecticide to control the aphids. Depending on the pest numbers, he may spray again in late June. He hasn’t seen any stink bugs yet which usually appear in early May. While these are Seplak’s two main insect concerns, he also encounters four-legged threats to his trees. “All year long, deer and javelinas chew on the foliage and strip branches off the trees,” he says. “The orchard can’t be fenced. I’ve tried the noise of cannons to keep them out. The deer just come back and sleep under the shade of the trees.” If his pistachio crop continues normal development, Seplak expects to harvest the nuts in late August. He hopes the monsoon rain storms hold off until he’s finished. “Over the last two years, we’ve been hit with rain at the tail end of harvest which really slowed us down,” Seplak says. “Harvest equipment doesn’t go through mud very well.”
Improved resistance management techniques in weed control in almonds
Dennis Pollock, Contributing Writer
A relatively wet winter has spawned the growth of weeds in almond orchards this year, but at the same time it has helped with the effectiveness of pre-emergent herbicides driven into the soil by the falling rain. That’s the observation of Brad Hanson, a University of California (UC) Extension weed specialist, who recommends a resistance management weed control program that blends pre- and post-emergent control for winter weeds and summer grasses. His basic thesis is that growers – without spending more to do so – can better control summer weeds by tweaking passes they already make across the field while applying herbicides. And Kurt Hembree, UC farm advisor for Fresno County, has offered tips on controlling summer weeds as well. Hembree said growers should look at whether new weeds are emerging and then select herbicides accordingly. This can vary from field-to-field, he said, and herbicides should be selected based on soil types. “Lower rates of pre-emergent products are often needed on sandier soils than heavier soils,” he said. Hanson said junglerice has joined the list of weeds that are herbicide resistant, including horseweed, fleabane, and ryegrass. Tank mixing different classes of chemistry to control winter weeds is a good strategy to broaden the weed control spectrum, Hanson said, but it does not necessarily enhance the duration of the application’s efficacy. He said junglerice is among annual weeds that typically germinate and emerge as the season warms in late spring and early summer. Other examples of confirmed or suspected glyphosate-resistant summer weeds include threespike, goosegrass, feather fingergrass, sprangletop, and witchgrass. Those problem weeds emerge long after typical orchard per-emergent herbicides are applied. He said growers with a history of summer grasses might want to consider extending residual control by using sequential applications of pre-emergent grass herbicides added to the winter pre and post-emergent tank mix and again at spring burndown. For example: In a typical weed management program, the pre-emergent may be added in winter, perhaps in late February or March. But if the grower has issues with summer grasses, use part of the pre-emergent in the spring. “Not just glyphosate, but Prowl or Surflan,” Hanson said. “Think of it as a booster shot in the spring,” he said, as residual effects of pre-emergents decline. “I’m proposing this as an idea; not a recipe,” he said. “The answer is not always more but better use, using the tools when we need them, and getting the most bang for the buck. To take his example further, if a grower uses four quarts of Prowl in January, perhaps they use two quarts for the winter application and two in March. “There’s not an extra cost,” Hanson said. “Maybe it’s two quarts and three, depending on weed pressure.” For the pre-emergent to be effective, it must travel to the top half inch or inch of soil. And it is moisture that drives it down. When it’s there, the seedling dies as it stops the root growth. Hanson acknowledged that the incorporation of pre-emergents can be an issue in a drip-irrigated orchard. He recommends growers time applications in advance of a rain in early March. “I think the cost should be nominal because we are moving the same herbicide to a time when growers are already making a pass across the field,” Hanson said. “We are not necessarily increasing the herbicide load with this strategy, but instead are using our knowledge about the specific weed problems present in an orchard and careful management to efficiently control weeds in a more environmental and economically sustainable approach.” As to increased rainfall and challenges this year, Hanson said, “We won’t be challenged beyond our capabilities.” Hanson said good burndown programs are essential, and heavy weed pressure may take several years to clean up. He strongly advocates using chemicals with varying modes of action to avoid developing resistance to sprays. Young trees are particularly vulnerable to weed pressures, he said, partly since there are not as many herbicides registered for use on those trees. Hanson said the biggest problem posed by weeds in almonds is interference with harvest operations. Machinery must sweep up nuts off the orchard floor, and clumps of weeds impede this. In one scenario, Hanson said a typical sequential herbicide program might have a post-harvest burndown in October or November. This would be followed with a pre- and post-emergent tank mix using broad spectrum chemicals that include Alion, Pindar GT, Chateau, and Matrix at two quarts per acre in December or January. Then, along with the spring burndown in March or April, add Prowl or Surflan at perhaps two quarts per acre for the March. The pre-harvest pass comes in June, July, or August. It may be done for burndown only, but it can combine the use of a short residual, perhaps pairing glyphosate with an oxyfluoren product such as Goal. Hembree said adding Treevix or Rely 280, Lifeline, or similar products to complement Roundup have proven effective on a wide variety of weeds. “Be sure to treat when the weeds are small for optimum control,” he adds.
T grafting in pistachio trees
Much has been written and spoken about budding root stock and existing pistachio nut trees. However, the true test is to have something simple which will produce the best results. More importantly, to have a procedure which can be performed by people with limited knowledge of the principles of plant growth. Those of you who have tried in vain to bud-graft pistachio root stock will know how frustrating and time consuming it can be, especially when the end result is a failure year after year. The basic requirement for budding is to have a close contact of the cambium layers (tissue between bark and wood) of both stock and scion. Some favour budding with chip buds, using dormant wood in the Spring just after sap movement. Extensive experimenting has proved (for me) that the best time is mid-January to early March when the sap is flowing at its peak, and now I only 'T' bud, using fresh budsticks taken from selected trees with large buds. The materials required are few and simple, Sharp and clean secateurs (preferably sterilised in methylated spirits or similar. Fresh budsticks which have been selected from trees free of virus diseases and other disorders. Bud sticks should be placed in a bucket of cold water when cut, and kept cool until budding. Budding from these bud sticks should be carried out the day the bud sticks are cut and at a temperature preferably no less than 20 degrees centigrade. Very sharp and clean budding knife (also sterilised in methylated spirits or similar). Good budding tape or budding rubbers (aged, ie one-year-old so that they perish easily). The simplest way of budding a root stock for pistachio nut trees is the common 'T' method. The incision is first made across the stock to be grafted (for the top of the 'T'), then a further incision is made from the top of the 'T' and down the stock for about 20 to 30 mm. Care must be taken to use only enough pressure on the knife blade to cut the bark so that it (the bark) can be freely peeled back from the wood using the back of the budding knife. The bark at the junction of the cuts can be lifted slightly. By a twist of the knife blade, and the flaps are then opened up by reversing the knife and sliding the bevelled bone end between the bark and wood. It is a good idea to splash cold water onto the area worked on to keep it moist. To cut the bud from the budstick, use the following procedure. Make the bud length about 20 mm. With a sharp knife, cut around the budstick below the bud. Hold the budstick with the bud facing you and the index finger of the left (or right) hand directly under the bud to be removed. Cut the bud away from the budstick with a continuous downward slicing movement of the blade, beginning 10 to 20 mm above the bud and finishing at the bottom cut. The cut should be deep enough to show a sliver of wood sticking to the bark when removed. After removal of the sliver of wood, it is a good idea to lightly scrape about 2 mm of bark off each end of the sliver to expose the cambium layer. Then dunk it into a bucket of cold water to clean it and keep it moist. To insert the bud, firmly hold the root stock with one hand, then with the other hand carefully slide the bud between the bark and wood where the incision was made for the 'T'. Now push the bud down towards the roots to a distance of 10 to 20 mm below the base of the 'T' incision. The bark will stretch and the bud should be under the bark and below where the incision was made. This is important, as the knife wound will damage the underlying layer, and this will result in the death of the bud if it is over it. To complete the operation. firmly bind over the incision with budding tape or budding rubbers. If the work has been successful, the bud will quickly push away, and within 2 to 3 weeks a shoot should appear in 20 to 30% of the buds. The rest will swell and remain dormant until next Spring. (The best result I have had was a shoot 320 mm long, one month after budding.) It is also possible the graft will flower the following year. Finally all foliage below the graft should be cut off. If budding tape has been used, it can be removed during winter, as the bud should be well-established. It is desirable to secure the tree to a stake and to support the new graft. As you can see, there is nothing new about budding except that correctly choosing the time of budding and bud selection (fresh swollen and mature buds) are essential. Overall, the success rate using the above procedure has been about 90%, compared with chip buds from dormant budsticks at about 10%.
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IRAN PISTACHIO NETWORK
پسته ایران یکی از منابع مهم ارز آوری و اشتغال در ایران محسوب میشود و هزاران نفر در صنعت پسته ایران مشغولند و از این راه امرار معاش می کنند. یکی از مشکلات مهم صنعت پسته ایران ورود افراد غیر متخصص در بحث پسته بخصوص بحث باغبانی و گیاهپزشکی است. هستند افراد زیادی که یک واحد سم شناسی نخوانده اند یا 4 واحد باغبانی عمومی یا 3 واحد خاکشناسی عمومی نخوانده اند و به کشاورزان توصیه کودپاشی و سم پاشی و ...می کنند!! تبعات عمل به توصیه های افراد غیر متخصص ممکن است سنگین باشد. بهتر است کشاورزان توصیه های مربوط به پسته را از افرادی دریافت کنند که حداقل رشته تحصیلی آنها کشاورزی باشد. تجربه صرف راه بجایی نخواهد برد. در بهترین شرایط تجربه 40 درصد کار است و 60 درصد حتمی قضیه علم و دانش کافی است. متاسفانه بسیاری از این افراد نامتخصص که گاها هیچ دانشی در زمینه کشاورزی ندارند از آشوب بازار نهاده های کشاورزی سو استفاده می کنند و دفتر و دستکی راه می اندازند و کارخانه ای و میخواهند جنس خود را بعنوان جنس برتر معرفی کنند!! متاسفانه بازار نهاده های کشاورزی بازار آشفته ای است و هر کس برای خودش کارخانه ای باز کرده و جنس خودش را بعنوان جنس برتر می فروشد. با توجه به گستردگی اقلیم پسته کاری بهر حال اگر حتی فردی کمترین سوادی هم داشته باشد می تواند از غفلت عده ای سو استفاده کند. در بسیاری از نقاط متاسفانه دانش کشاورزان ما بالا نیست و موجب سو استفاده توسط ایندسته از سودجویان شده است. فردی که دکتری مهندسی دارد بهتر است در رشته خودش فعالیت داشته باشد و یا حداقل اگر باغدار است در همین حد بماند و کشاورزان را گمراه نکند. مثالهای بسیار زیادی از ضرر و زیان افراد نامتخصص در بخش باغبانی وجود دارد که دهها صفحه را بنده میتوانم شخصا ارایه دهم. وقتی کسی فرق لارو و حشره کامل و شفیره را نمی داند چگونه بخود اجازه می دهد توصیه کارشناسی به کشاورزان بدهد؟!! صنعت پسته ایران دارای بخش های متعددی است و باید افرادی توصیه بدهند که علم اینکار را داشته باشند. مهندس صنایع چگونه میتواند درباره درخت پسته اظهار نظر کند؟؟ دکتری فیزیک چگونه میتواند در مورد شوری اظهار نظر کند!! اگر فقط بصرف خواندن چند جزوه و شرکت در چند سمینار و گردهمایی عده ای به خود اجازه میدهند که در بخش باغبانی و گیاهپزشکی دخالت کنند بهتر است درب دانشکده های کشاورزی را ببندند و اینهمه عمر جوانان و محصلان تلف نشود و منبع دولتی پرت!! یک کارشناس یا ارشد یا دکتری کشاورزی عمری را در آزمایشگاه های تخصصی گذرانده و ترم ها درس خوانده و پروژه گذرانده. چطور یک نفر بخود اجازه میدهد نظر تخصصی در مورد آفات بدهد در صورتی که هنوز یک حشره را از نزدیک زیر بینوکولار ندیده!!! چطور میشود در مورد مدیریت مبارزه با بیماریهای پسته نظر داد وقتی هنوز طرف میکروسکوپ را به عمر ندیده!! چگونه میتواند فردی در مورد علفهای هرز نظر بدهد که هنوز اسم علفهای هرز را نمی داند!! طرف هنوز نمی داند دگردیسی چیست؟ میخواهد فلان سم را توصیه کند!! اینها بیشتر سودجویانی هستند که دنبال فروختن اجناس خود به ملت ناآگاه هستند تا خدمت به کشاورز. دسته دیگری از این افراد چون در رشته خوشان موفق نبوده اند میخواهند از نمد پسته کلاهی برای خودشان ببافند. جالب اینجاست افرادی هستند بیسواد که وارد کننده و توزیع کننده نهاده های کشاورزی هستند و متاسفانه برخی کارشناسان از روی اجبار زیر بار حرف زور می روند!! برای یک کارشناس کشاورزی یا تحصیلکرده کشاورزی زشت است توصیه را از کسی بگیرد که اصلا درس کشاورزی نخوانده و برایش به به و چه چه هم بکند و زیر بار حرف زور برود. بهتر است افراد غیر متخصص در سطح خودشان اظهار نظر کنند و کشاورزان را گمراه نکنند. بسیاری از افراد متخصص بخاطر همین مسایل سکوت کرده اند و می کنند. امیدوارن روزی فرا برسد که در مورد مسایل تخصصی پسته افرادی اظهار نظر و توصیه کنند که تخصص کشاورزی دارند. شاید عیب بزرگ کار این باشد که کارشناسان و فارغ التحصیلان از اظهار نظر هراس دارند. باید این ترس بشکند و مخصوصا افراد تازه فارغ التحصیل ارشد و دکتری که سواد بالایی هم دارند بصورت قدرتمند وارد شوند و دست این افراد سودجو و پر مدعا را از سر پسته ایران قطع کنند. افرادی که فارغ التحصیل کشاورزی هستند بمراتب می توانند از افراد بیسواد و افرادی که رشته کشاورزی نخوانده اند موفق تر عمل کنند. باید افراد تازه نفس را وارد کار کرد چون هم انرژی کافی دارند هم انگیزه و هم دانش و علم لازم. من شخصا هیچگاه در زمینه های غیرکشاورزی اظهار نظر نکرده ام و نمی کنم چون دانش لازم را ندارم. یک پزشک یا مهندس مکانیک یا شیمیست یا فیزیکدان و ریاضیدان بهتر است پاسخگوی مشکلات در زمینه کاری خودشان باشند و موجب گمراهی بیشتر کشاورزان نشوند. توصیه های معمولی و روتین کشاورزی را باغداران بهتر از ما کشاورزان بلدند و بهتر است تخصصی اظهار نظر کنیم. به امید فردایی بهتر برای صنعت پسته.
A new invention, Organic Chelated Iron 8%
fertilizer stable at pH 1-12 best substitute for
Fe-EDDHA and Fe-EDTA
Dr. Behzad khosropanah, Research Scientist in
Agriculture & fertilizer industry, Canada
Iron deficiency is a limiting factor of plant growth. Iron is present at high quantities in soils, but its availability to plants is usually very low, and therefore iron deficiency is a common problem. Although most of the iron on the earth crust is in the form of Fe3+, the Fe2+ form is physiologically more significant for plants. This form is relatively soluble, but is readily oxidized to Fe3+, which then precipitates. Fe3+ is insoluble in neutral and high pH, making iron unavailable to plants in alkaline and in calcareous soils. Furthermore, in these types of soil, iron readily combines with phosphates, carbonates, calcium, magnesium and hydroxide ions. Plants uptake iron in its oxidized forms, Fe2+ (ferrous form) or Fe3+ (ferric form). Plants use various iron uptake mechanisms. One of these is the chelation mechanism - the plant releases compounds called siderophores which bind iron and enhance its solubility. This mechanism also involves bacteria. Another mechanism involves the release of protons (H+) and reductants by the plant roots, to lower pH levels in root zone. The result is increased iron solubility.In this respect, choice of the form of nitrogen fertilizer is significant. Ammonium nitrogen increases proton release by roots, thus lowering pH and facilitating iron uptake. Nitrate nitrogen enhances the release of hydroxide ions that increase pH in the root zone and counteract efficient iron uptake. New roots and root hairs are more active in iron uptake, therefore it is imperative to maintain a healthy active root system. Any factor interfering with root development interferes with iron uptake. When iron deficiency is identified, it can be treated in the short term by applying a foliar spray of iron, but the best course of action is prevention. Therefore, the grower should identify the real cause of the deficiency and treat it, in order to prevent the problem from occurring in the future. Often, iron deficiency does not indicate insufficient iron supply. It may also be related to various conditions that may affect iron availability. For example: carbonate levels in the soil, salinity, soil moisture, low temperature, concentration of other elements (e.g. competitive microelements, phosphorus, calcium) etc. Evaluating these factors and correcting them can save a great deal of money spent on ineffective and unnecessary iron applications. Iron can be applied as ferrous sulfate or in a chelated form. Ferrous sulfate (FeSO4) contains about 20% iron. This fertilizer is inexpensive and is mainly used for foliar spraying. Applied to soil, it is often ineffective, especially in pH above 7.0, because its iron quickly transforms to Fe3+ and precipitates as one of the iron oxides. Iron chelates. Chelates are compounds that stabilize metal ions (in this case - iron) and protect them from oxidation and precipitation. Iron chelates consist of three components Fe3+ ions. A complex, such as EDTA, DTPA, EDDHA, amino acids, humic-fulvic acids, citrate. Sodium (Na+) or ammonium (NH4+) ions. Different chelates hold iron ions in different strengths at different pH levels. They also defer in their susceptibility to iron replacement by competitive ions. For example, at high concentrations, calcium or magnesium ions may replace the chelated metal ion. Fe-EDTA - This iron chelate is stable at pH below 6.0. Above pH of 6.5, nearly 50% of the iron is unavailable. Therefore this chelate is ineffective in alkaline soils. This chelate also has high affinity to calcium, so it is advised not to use it in calcium-rich soils or water. Note that EDTA is a very stable chelate of micro-elements, other than iron, even in high pH levels. Fe-DTPA - this iron chelate is stable in pH levels of up to 7.0, and is not as susceptible to iron replacement by calcium. Fe-EDDHA - this chelate is stable at pH levels as high as 11.0, but it is also the most expensive iron chelate available.
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