Category Archives: Fertility

Pecan Mouse Ear

Mouse ear is a growth abnormality from a nickel deficiency in pecan trees. This disorder occurs mostly on newly transplanted trees in established orchards. This is the first time I’ve seen it, but it is close to the text book pictures and easy to ID. Mouse ear first appears on the spring growth flush. The most common symptom of mouse ear is a rounded or blunt leaflet tip. Other symptoms include dwarfing of tree organs and necrosis of leaflet tips. The degree of severity with the tree canopy typically increases with canopy height.

Mouse ear symptoms

Mouse ear symptoms, rounded or blunt tip

Necrotic leaf tips due to build-up of lactic acid from Ni deficiency.

Necrotic leaf tips due to build-up of lactic acid from Ni deficiency.

There are 4,000 seedling trees in this nursery and probably half are affected by the Ni deficiency. At this point we need to spray a foliar application of nickel now and again in one month. UGA Pecan Horticulturalist Dr. Lenny Wells says mouse ear may consistently reappear from year to year, or appear on occasion. For mouse ear prone sites, it is recommended to have a foliar spray of nickel in med-late April when leaves are in the parachute stage. (Ni is not absorbed in the plant until leaves are in parachute stage.) We follow up with an additional application in late September or early October to prevent mouse in the following spring.

Long-term Management (From Southeast Pecan Grower’s Handbook)

  1. Monitor leaf and soil samples for availability of Ni to trees.
  2. Don’t make excessive applications of zinc. Zn competes with and inhibits uptake of Ni. Foliar Zn should only be applied when Zn leaf levels are less than 50 ppm or when visual Zn deficiency symptoms are present. Do not allow soil to become acidic (making Zn more available.)
  3. Maintain good soil moisture at budbreak. Ni is relatively low in the soil in most orchards, and it is absorbed by the tree in the lowest of many nutrients.
  4. Maintain soil pH at 6.5.
  5. Do not give late applications of N, to ensure that senescing foliage can translocate to shoot and bud storage prior to defoliation.
  6. Manage phosphorus, iron, and copper levels in soils. These nutrients affect uptake of Ni. They may also alter the availability of Ni within the leaf.
Rosetting of leaves from Ni deficiency.

Rosetting and necrotic tips from Ni deficiency.

 

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Satsuma Fertilization

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Blooms & new growth

Blooms & new growth

Thanks to Lowndes County Agent Jake Price who did a good job coordinating Monday’s Satsuma Meeting. We talked about citrus greening, fungal disease, and fertility programs.

We’re actually a few weeks past beginning bloom here, and with a warmer winter, we are seeing lots of terminal growth this year already. These trees are in their 2nd and 3rd year, and the fruit will not quite be tasty yet. Many of these blooms will actually be removed. Limbs of Owari grow outward, and many of the fruit can touch the ground with a younger tree. All of the varieties are self-fruitful, so no pollinizer trees are required. Bees may also help, but are not required.

Fertility Program

Our pH needs to around 6.0. A wider range is between 5.5 and 7.0. We need to lime if we are 5.5 or lower. In this range, nutrients are most available for uptake for Satsuma.

When we fertilize, much of our rates are based on N, since they are considered ‘heavy feeders.’ We start fertilizing at

  1. First sign of budbreak in the Spring (late Feb/early March)
  2. Fruit swell (May)
  3. Fruit are 1 inch in diameter (June)

We don’t want to use fertilizer with N from September to mid-February since this could comprismise cold hardiness.

We can use either a complete fertilizer (8-8-8) or a straight N fertilizer (34-0-0), or a combination. We only use a straight fertilizer if soil tests and leaf analysis show other elements are not necessary. Here is a general baseline N recommendation for Satsumas of different ages from research in Alabama:

CitrusFertilization-Florida

Poultry Litter

Some planting this year will use poultry litter. The fertilizer value of poultry litter depends on many factors like moisture, temperature, feed rations, storage, and handling. It is best to check analysis of poultry litter. Poultry liter has an approximate analysis of 3-3-2 (60lbN – 60lb p2O5 – 40lbK2O). Here is some poultry liter rates from UGA Extension Fruit Scientist Dr. Erick Smith:

ChickenLiter-E.Smith

Satsuma Meeting in Lowndes County

Satsuma Meeting in Lowndes County

 

 

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Forage Update & Winter Fertilization Considerations

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We’ve been looking at more and more forage issues the past few weeks. Rust is evident in some fields. We’re also seeing evidence of N efficiency as lower leaves show chlorosis. Here is an update on our forage crops from UGA Extension Forage Scientist Dr. Dennis Hancock:

Yet again, the weather is making farming a high stakes game of chance. We had a very wet end to the summer growing season (in most areas) and this resulted in the leaching out of almost all of the residual N in the soil. Then, we’ve had lots of warm weather lately, and this has encouraged disease issues to severely limit the growth potential of winter forages. The warm weather has also allowed for some additional N mineralization to occur, but this N hasn’t stuck around long enough to provide N to our winter forages. That is because we’ve had quite a bit of rainfall in the past several weeks (pretty much the whole state) and what little available N was released has quickly been leached away. Many (if not most) of our winter forage crops are starving for N at the moment. Even fields with good stands of clover are suffering because these legumes aren’t yet fixing much N (because the soils have been so water-logged that they can’t fix N).

To make matters worse, the weather projections are not particularly positive. The models suggest a lot more of the same on the near-term: mild to cool temperatures and above normal rainfall through March-April. They also project a short end of spring: above normal temps fairly normal rainfall in late April – June.  This means that the remaining bit of the production season is likely to be compressed from what is normally a February – May growing season in a good year to what may be just March – April in some areas.

Ryegrass

Standard soil test recommendations are that one should put out 50 lbs of N/acre on ryegrass and small grains in late winter (late January – February) and another 50 lbs of N/acre on ryegrass in early spring (mid-March – mid-April). Applications of N at these rates are likely to result in more than 15-20 lbs of DM per lb of added N for the late winter application and more than 20-25 lbs of DM per lb of added N.  As a general rule of thumb, N response rates greater than 15-20 lbs of DM per lb of added N will result in an economical response.

This year, timely action with the winter applications will be absolutely crucial. Even if adequate N was applied at planting, it is likely that little or none of that is still available at the time of this writing.

The response to N (lbs of DM gained per lb of added N) has to be considered in context. To illustrate this, let us consider three scenarios:

Scenario 1) Ryegrass or small grains that have been slow to grow, either because of bad weather or N deficiency (and, sometimes, a late planting). These winter annual forage crops will often respond very aggressively to a winter application (20-30 lbs of DM per lb of added N assuming N rates are 40 – 60+ lbs of N/acre).  It is analogous to compensatory gains in growing livestock. It is the same basic principle: an organism that has had growth limitations will often grow at extraordinary rates whenever those factors are no longer limiting.

Scenario 2) Ryegrass or small grain plantings that have been growing strong. Winter annual forage crops in this scenario are unlikely to respond as aggressively to N at this time. For example, they may barely provide 15 lbs of DM per lb of added N during the few weeks following N application. However, this N is still crucial, as it keeps the plant growing at least at a healthy rate. Therefore, it is important to fertilize them at the same or nearly the same rates because they will need the fertility during the remainder of the season.

Scenario 3) Winter annual forages that have been moderate to severely damaged by disease (Helminthsporium leaf spot, grey leaf spot/blast, leaf rust, or barley yellow dwarf virus, etc.). These forage crops are unlikely to respond to N application. For example, tillers that are exhibiting physical symptoms of barley yellow dwarf (BYD) infection will die quickly, especially following a hard freeze. Therefore, if more than 30% of the tillers in a stand of oats have been damaged by barley yellow dwarf, those plants are unlikely to respond well to N. Each producer will have to determine if they are willing to take the risk, but if it were my oats, I doubt I would put any more N into those areas/fields.

Oats

Another consideration is the growth cycle of the crop. Here again, oats provide us a good example. Oats generally grow very well in the fall and in the spring, but not very well in the winter. The N recommendations for small grains as winter grazing states “…these crops can utilize about 100 (lbs of N) per acre during the growing season. Split the (N) application, applying 50 (lbs of N) per acre at planting and 50 (lbs of N) per acre in late winter before spring growth begins.” The instruction to apply 50 lbs of N/acre in late winter for small grains applies to oats, as well as to rye, wheat, and triticale. However, the operative part of this recommendation is the final phrase “in late winter before spring growth begins.” The spring growth of rye, wheat, and triticale have already begun or will do so imminently.  The spring growth of oats really won’t begin until early March.  Therefore, one would be wise to delay the late winter application of N to oats until the end of February.

Which Form of N?

Last, but certainly not least, one should consider the form of N being applied. If a producer applies ammonium nitrate, the fertilizer quickly dissolves into the soil moisture. Consequently, this source of N is almost immediately available to the plant. However, most of our producers no longer have access to ammonium nitrate.

Many of the N products that are most readily available are based on urea.  Urea and urea-based N formulations are, chemically speaking, organic forms of N. Urea must be broken down via a biological process to form nitrate, which is the form of N that plants predominantly absorb. Because this process is dependent upon the activity of microorganisms in the soil, weather can effect how rapidly this N becomes available to the plant. Cool and wet weather slows down the conversion of urea to a form of N that is available to the plant. Many producers will put on a significant amount of urea only to find that their crop fails to green up. This is NOT because they received “bad fertilizer.” It may be the result of the cool, wet weather.

Poultry litter is a great source of N… in the summer months. But, in the winter months, it is marginal at best. The reason for the difference is that most of the N is in an organic form. Just like the urea, the N in poultry litter has to be broken down by biological activity (bacteria) in order for it to be made available to the plant.  Further, putting poultry litter out now (February) is likely to pose an environmental risk such as the contamination of runoff water and therefore contaminating the water in your ponds, streams, and other freshwater resources. Of course, that assumes that poultry litter is even available to put out now or that one could get one of those trucks in the field at present, given how wet the soil is at present. Many producers apply poultry litter in the fall whenever they plant their winter grazing. This gives it a little bit of N to get off to a good start. But, it doesn’t provide much during the winter.

There are three reasonably good alternatives to these aforementioned N sources. The first one to be considered is liquid N (UAN), which is approximately half urea and half ammonium nitrate. Because of the ammonium nitrate portion, it is more readily available to the plant than many other N sources.

One should also consider using either Agrotain Plus-treated urea or SuperU. Both of these products are urea-based, but are sold under different trade names. Both are treated with a urease inhibitor (N-butyl-thiophosphoric triamide), which prevents loss as ammonia, and a nitrification inhibitor (dicyandiamide), which prevents N loss to leaching.  These still have the challenge of urea’s slow release, but they are less likely to be lost to the environment as ammonia gas or nitrate leaching into the groundwater.

Last, but not least, one should consider using the 18%N 19E product, which is a liquid N product. This product is essentially liquid calcium ammonium nitrate with sulfur and a few other micronutrients.  The N from this product, like ammonium nitrate, is almost immediately available to the plant. Further, it is often quite economical compared to other N sources because it is locally produced.

N deficiency in triticale

N deficiency in triticale. Lower (older) leaves turn yellow since N is mobile in the plant.

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Winter Forage Fertilization

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Our forage crops look much better now than they did this time last season. October was dry just like last season, but some soil had enough moisture to get a stand though mid October. Last year, frosts and rain hurt us. We checked some oats for aphids and found none this week. Aphids were also a big issue this time last year.

We are talking about fertility programs in our forage crops compared to our grain crops this week. When we plant wheat for grain, we go out with our recommended N based on previous crop at planting. We then check the stand in January to see how tillering is doing. If we have enough tillers, we hold off and put out the rest of our nitrogen at one time. If tillers are low, we split nitrogen to encourage tillering.

The difference in our forage crop UGA Extension Forage Scientist Dr. Dennis Hancock says that we only intend to increase our vegetative growth. With grain, we want to count tillers and fine tune our nitrogen. “With forage we want apply 40 – 50 lbs of N per acre at planting or soon after the plants emerge to increase growth, tillering (thickening of the stand), and provide earlier grazing. A second application of 40 – 50 lbs of N per acre should be applied in mid-winter to increase winter and spring forage production. Because ryegrass is longer-lived, a third application of 40 – 50 lbs of N per acre may be needed in early spring when ryegrass is used for late spring grazing, hay, or silage crop. Rates of N in excess of these amounts may result in substantial N losses to leaching and excessive growth during the winter. Fresh, tender growth that occurs when nitrogen is in excess could be damaged by extremely cold weather.” More information on fertilization can be found on the Georgia Forages website.

As weather turns colder, there are some issues we will have in our grazing crops. Most fields this year are oats, rye, ryegrass or a blend. Oats are more susceptible to cold injury than other small grains. With cold injury, we will see purpling of the foliage. The purpling is the result from accumulation of anthocyanins after temperature drops. We do not expect permanent damage, as the growing point is below ground during the tillering stage until jointing.

Purpling due to cold injury in oats

Purpling due to cold injury in oats

This reddish/purple color can also indicate barley yellow dwarf virus. These symptoms start from the tip of the leaf blade. The virus is vectored by aphids which are observed on the foliage. Most fields will have some level of BYDV each season. We are not seeing aphids now, so this is less of a concern.

Another cause of purpling is due to phosphorus deficiency. P is not soil mobile and is taken up by root ‘interception meaning’ the roots must grow to it. Cold can decrease root growth and this becomes evident. Nitrogen and potassium on the other hand are soil mobile. They can leach down into soil profile with rain. This time last season, rain was leaching N out of the soil. N is also mobile inside the plant, so older or lower leaves will show deficiency first.

Nitrogen deficiency in wheat

Nitrogen deficiency in wheat

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Cover Crop Following Peanuts

CoverCrop

With most of our peanuts out of the ground, we’re looking at putting in cover crops with  talk of an El Niño year. UGA Extension Soil & Fertilizer specialist Dr. Glenn Harris answers the question: Should we give that cover crop which follows peanuts a nitrogen (N) credit (lower than normal N fertilization) since our peanut harvest was good?

Short answer: No!

UGA Extension recommends 20 to 40 pounds per acre credit to a cover crop after peanuts.

UGA Nitrogen recommendations for Rye, Wheat & Oat fall planting are 20 to 40 pounds per acre at planting following peanuts and another side dress application in February are the standard nitrogen recommendation in Georgia.

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Cool Season Pasture Establishment Tips

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It’s been very dry for planting our grazing. Some grazing has been planted like this one but many growers are waiting for the rain. The rain is predicted for this week. This field was planted the first week of October. It’s Horizon 306 variety of oats. They harrowed, spread chicken liter, dressed again, then drilled in seed. Here is some information from UF Soil & Nutrient Extension Specialist Dr. Cheryl Mackowiak:

Preparing Land

Prepare land for winter grazing by closely grazing or mowing down the existing pasture in the fall, prior to planting. This results in less water, nutrient, and light competition with the emerging cool-season forages. You can also till an area for producing cool-season forages. Forages started in tilled soil will grow faster and often outperform over-seeded forages. A prepared seedbed minimizes competition for resources and during cooler periods, the exposed soil will warm more than soil under residues.

pH/Lime

Target soil pH to a range from 5.5 to 6.5. If you find that your soil is near the low (acidic) end of the scale, consider applying lime. However, do not apply lime within a month of your fertilizer application, as you may increase nitrogen volatilization (N loss) and tie-up more soil phosphorous (P), leading to less available fertilizer for the plants. If you have not limed yet, you might consider waiting until winter, or before the spring transition into summer forages.

Fertilization

For cool-season grasses in Florida & SW Georgia, 30 lbs N/acre is recommended at or near planting, then another 40 to 50 lbs N/ac after the plants have established (beginning to branch or tiller). If you want greater clover competition, apply less N (30 to 50 lbs near planting and no additional application). Under grazing, you might find that applying another 30 to 50 lbs N/acre in early spring is required, particularly if there are leaching rains, or livestock are not redistributing excrement uniformly across the pasture. If El Nino conditions prevail through the 2016 winter/spring, you may find yourself under flooded conditions. Annual ryegrass and white clover survive saturated soils better than most other Florida cool-season forage options. Saturated soils will also lose N via denitrification (gaseous loss). Do not apply additional N fertilizer until the soils have adequately drained.

FaithPittman-Weed 031Planting Dates

Planting now through mid-November ensures well-established plants with deep root systems to capture nutrients that may leach during large rain events. Also, managing grazing to retain adequate forage (3 inches or more stubble height or grazing to remove only half of your canopy height) will insure adequate rooting mass and depth, in order to capture soil nutrients deeper in the soil profile and promote stronger, more resilient plants and faster regrowth.

Keep in mind that the fertilizer investment made for cool-season forages will be returned in animal gains and a healthier pasture. The root mass from winter forages decomposes in early summer, contributing organic matter and slow-release nutrients to the soil that will help support the summer pasture.

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Potash Deficiency In Cotton

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We’re seeing signs of potassium deficiency in cotton more and more, but it’s not all bad. The signs are stemphyllium leaf spot. These are the circular spots on the leaves with red borders that may have “shothole” appearance. Where K deficiency is more severe, we see discoloration on the leaf also. UGA Extension Fertility Scientist Dr. Glen Harris says because it is late in the year, we should see more stemphyllium. If the plant is loaded with bolls, it has used up a lot of its potassium. If the plant doesn’t have many bolls, stemphyllium or K deficiency may have occurred earlier and caused more of an issue.

Correcting K Deficiency

UGA recommends putting out K with pre-plant fertilizer. However, even with 90 lb in this field, it may have not been enough. Where a known K deficiency exists, foliar K applications should be considered. Even with foliar K, we may not be putting enough where this stemphyllium is heavy. Two foliar applications of 5 – 10 lbs/K2O in each application during early bloom (1st through 4th week) need to be considered.

Stemphyllium Leaf Spot

Stemphyllium Leaf Spot

Dr. Harris says in most cases, the best way to avoid K deficiency is to:

  1. Soil test
  2. Apply recommended K fertilizer at planting
  3. Consider foliar feeding K during peak bloom

How late is too late to foliar feed?

We’re now pushing 5 – 7 weeks of bloom or more in most fields. Based on research, foliar fertilization is most effective when applied during peak bloom or 4th week of bloom. Foliar feeding during 5th and 6th week of bloom may not be effective depending on cotton variety. Once we hit 7th and 8th week of bloom (and after), foliar feeding is too late – not recommended.

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Sidedressing Cotton

As cotton is squaring throughout the county, we need to also think about sidedressing. Here are some thoughts on sidedressing from the 2015 UGA Cotton Production Guide.

Nitrogen (N) Management

N can be very difficult to manage. Base N rates recommended by UGA Soil Testing Lab according to yield goals are blow:

YieldGoal-2015

These rates should be adjusted according to other factors:

  • Increase N by 25% if – Deep sandy soil, cotton following cotton, history of inadequate stalk growth.
  • Decrease N rate 25% if – Cotton following peanuts or soybeans, cotton yellowing good stands of winter legumes, history of rank/vegetative growth.

UGA Extension Scientist Dr. Glen Harris says our N rate should be applied in split applications since N is mobile in the soil. We want to apply 1/4 to 1/3 of recommended N at planting and the reminder at sidedress. Sidedress N between first square and first bloom. (If cotton is growing slow and pale green, sidedress more towards first bloom.) Sidedress N can also be applied as foliar treatments or through irrigation. No N should be soil-applied (including pivot) after 3rd week of bloom.

Phosphorus (P) & Potassium (K) Management

P & K need to be maintained in the upper medium range by soil testing. All of the P requirements should be applied preplant since it is relatively immobile in the soil and important to seedling growth. K should also be applied preplant on all soil types including Piedmont, Coastal Plain, and Deep Sand soils. Split applications of K have not proven to be effective ton Tifton type soils. Recent field trials in GA have focused on additional soil-applied K during N sidedressing versus foliar K during peak bloom (4 weeks bloom). Dr. Harris says results on Coastal Plain soils indicate that foliar K may be more effective than sidedress K in improving yield.

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Stemphyllium Leaf Spot

Currenty, foliar K applications should automatically be considered on deep sands, low K soils, high Mg soils, high=yielding conditions, short season varieties and where K deficienes have occurred. Cercospora, Alternaira and Stemphyllium leafspot have all been linked to K deficiency. They are secondary to K deficiency. Corynespora leafspot does not appear to be linked to K.

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Corn Purpling

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Here is some dryland corn planted in central Thomas County that has shown these purple symptoms for some time. This purple on the outer edges of the leaves is due to a phosphate deficiency. This corn is in the V5 growth stage, and we would normally see these symptoms earlier than now. UGA Extension Fertility Scientist Dr. Glen Harris says symptoms of phosphorus deficiency are different within variety. One variety may show more purpling than another.

Phosphate deficiency in corn

Phosphate deficiency in corn

This field was soil tested and the proper amount of P was put out at planting. Dr. Harris says the cooler temperatures have allowed this to show up. Phosphorus is not soil mobile and is taken up by “root interception.” When soil temperatures drop and roots cease to grow, phosphate deficiency results. If this field had no P at planting, then it would be recommended to apply some 10-34-0. Since P was put out at planting, the corn will grow through this.

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P, K, Zn Fertilization On Young Pecan Trees

Here is information from UGA Extension Pecan Specialist Dr. Lenny Wells and fertilizing young trees:

Most soils on which new pecan orchards are established here in Georgia are old row crop fields or cleared pine land. In the case of row crop fields, soil levels of P and K may be in fairly good shape, while Zn levels and pH are low. On cutover pine land, everything tends to be low. Desired soil levels for these nutrients should be 60 lbs P, 100 lbs K, and 15 lbs Zn by the time the trees begin production. It takes a few years for surface applications of these nutrients to reach the trees. The sooner growers can get up to these levels, the better. In general, once you get P, K, and Zn levels to this desired range, they tend to remain there for quite a while because so little is removed with the crop or lost to the environment in an orchard system.

Our general recommendation for fertilization of young trees is to apply 10-10-10 + Zinc Sulfate by hand to each tree. With regard to tree growth and leaf N status, this still appears to be an effective and efficient method of fertilization. As far as the tree is concerned, there is no difference between this method and fertigation. There are a number of growers who are applying fertilizers through the irrigation system on young trees. There is nothing necessarily wrong with this. It can be done safely as long as the irrigation system is in good working order. In fact, for larger orchards, fertigation may be an easier and more efficient method of fertilizing young trees from a labor stand-point. However, the best use of fertigation is for the application of N. Our trials have shown that 25 lbs N per acre applied via fertigation is excessive for first through third year trees. A more reasonable rate would be 10 lbs N per acre (and that may be high as well). The tree will only use the N it needs and excessive N will leach from the root zone, therefore N must be applied annually in a manner suitable for optimum uptake. However, earlier P, K, and Zn are more stable in orchard soils.

Young Pecans 023

As young trees grow their roots are exploring the soil at a length twice that of the canopy width. Therefore the roots of a young pecan tree quickly outgrow the area wet by the irrigation system. In newly established orchards, this area may remain deficient of P, K, and Zn for a number of years unless dry broadcast applications are made to bring soil levels up to the desired range. With fertigation of these nutrients, the wetted zone may be sufficient but the larger area around it in which the roots are trying to explore is still low. This is especially critical for P, which plays a large role in root growth.

The tree will reach a point in which it needs sufficient P, along with K, and Zn in the entire root zone for optimal growth and production. Broadcast applications beginning with directed applications toward the herbicide strip in young trees will help get these soil levels up in a broad swath around the trees. As the trees grow and leaves are deposited in the middles, they redistribute and recycle these nutrients back into the orchard soil. A broadcast application of poultry litter is also a good way to elevate levels of these nutrients in the orchard. Begin building up soil levels early on young pecan trees in order to avoid problems down the road.

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