Production Pointers - Dr. Steve Phillips

June 20 – Crop Nutrient Uptake and Removal
How many lb of N did your wheat take up? How many lb of N were removed in the harvested grain? What about corn, or grass, or tomatoes? With so many states in the region implementing nutrient management planning criteria that consider crop nutrient removal, it is becoming increasingly important that growers have a feel for nutrient uptake rates for their crops. Many people are surprised when they find out the actual quantities of nutrients required to achieve their target yields. Nutrient uptake and removal tables for most crops grown in the region are available on the IPNI website at nase.ipni.net.

June 10 – Lawn Fertilization – N
Adequate amounts of N are necessary to maintain a healthy, green lawn. Like hay and pasture grasses, N is most efficiently utilized by splitting the N rate into multiple applications. For most lawn grasses, a typical recommendation is to apply 1 lb N/1000 ft² when spring growth begins and again in mid-summer. For thicker, greener grass, this application can be made on 2-month intervals during the growing season. Urea, ammonium sulfate, or any water-soluble N source can be used on lawn grass; however, over-application of N can result in leaf burning.

June 1 – Balanced Fertility for Bermudagrass Production
The right balance of N, P and K can contribute to several factors that lead to more efficient and productive bermudagrass systems. For example, P and K fertilization increase the percentage of N recovered in the harvested crop, which is directly related to protein content. Maintaining adequate levels of all nutrients increases rooting depth and reserves that are critical for rapid re-growth following harvest. Research in GA showed that soil water use is less following annual N-P-K applications compared to an unfertilized control (9.8 vs 2.7 inches/ton forage produced).

May 20 – Bermudagrass Fertility – K
Bermudagrass will take up more K than any other nutrient, approximately 50 lb K₂O/ton forage. In the southeast, where yield potentials can be as high a 7 to 8 tons/acre, K₂O requirements can approach 400 lb/acre. Inadequate K fertility can result in plants that are more susceptible to diseases, like fungal leaf spot, early stand decline, drought stress, and winter-kill. Good soil testing and fertilization programs are the best way to monitor and maintain soil K levels.

May 10 – Bermudagrass Fertility – P
Phosphorus is needed for photosynthesis, respiration, energy storage and transfer, cell division and enlargement, and many other processes in plants. A ton of bermudagrass forage will take up approximately 12 lb P₂O₅. So, a 7-ton yield requires 84 lb P₂O₅/acre/year. Following soil test-based recommendations is the best way to ensure that P fertility levels are adequate for bermudagrass production. Many soils in the southeast test high in P; however, continued nutrient removal without replacement can be costly. Maintaining adequate soil-test P levels and balanced fertility are critical for high quality bermudagrass forage production.

May 1 – Bermudagrass Fertility – N
The goal in bermudagrass production is to produce a quality feed source high in protein and total digestible nutrients and good N management can help. A ton of bermudagrass forage will take up approximately 45 lb N. So, a 7-ton yield in the southeast will require about 300 lb N/acre. Nitrogen should be split-applied for best results. Typical recommendations suggest applying 60 to 100 lb N/acre when the grass begins to green up then an additional 60 to 100 lb following each hay cutting. For pasture, apply 60 to 100 lb N/acre in the spring then an additional 40 to 60 lb after each graze-down.

April 20 – Tissue Testing
By the time nutrient deficiency symptoms appear in the leaves, all other plant parts have been affected. Petiole or leaf analysis can identify nutrient deficiencies up to two weeks in advance of any yield reductions and can also be used to determine the need for sidedress or foliar nutrient applications. Contact your local CCA, fertilizer dealer, or extension specialist for instructions on proper tissue sampling. The best defense against nutrient deficiencies is a combination of soil testing, tissue testing, and proper fertilization.

April 10 – Sidedress N for Corn
Spring in the southeast is often very wet, increasing the likelihood of N losses. Corn takes up less than 10% of its total N requirement early in the season, making it an ideal candidate for split N applications. The time when rapid vegetative growth (and the highest demand for N) occurs varies depending on regional temperatures; however, most recommendations suggest targeting somewhere around the V6 growth stage to make the in-season N application (typically 2/3 of the total required rate). Applying too much N early, particularly in a wet year, can reduce efficiency and be less profitable.

April 1 – Starter N in Rice
Semi-dwarf rice cultivars have increased in popularity in the southern U.S.; however, emergence and seedling growth rates can be lower compared to taller cultivars. Starter fertilizer applications have proven to be beneficial in increasing early-season vegetation and sometimes yield in corn, cotton, and soybean and recent research indicates that rice responds favorably as well. Mississippi research data show that applying 20 lb N/acre as ammonium sulfate or diammonium phosphate at the two-leaf stage can increase five-leaf stage plant height, which can have positive management implications such as earlier flood establishment. Starter N applications can also result in moderate grain yield increases compared to no starter application.

March 20, 2014 – Spring P Applications for Rice
Many rice growers apply P fertilizer in the fall when fields are dry and being prepared for spring planting. However, university research in Mississippi indicates that waiting until spring to make recommended P applications can increase rice yields 8 to 9% compared with fall applications. Many growers make a starter N application between planting and just prior to flooding. In fields where P is needed, a source like 18-46-0 can be used to supply a small amount of starter N as well as satisfy the P requirement for the crop.

March 10, 2014 – Long-Term Pasture Health
Allowing nutrients to fall below optimum soil test levels is not in the best interest of long-term pasture health. If nutrients removed in the forage are not replaced, stands will decline resulting in lower forage yield potential. It is particularly difficult to economically justify reducing fertilization of any field that is to be cut for hay because of the significant fixed costs associated with hay production. As yields increase, there are more tons of hay to spread these costs over; thus, it pays to monitor pasture fertility and to protect high forage yield potential.

March 1, 2014 – Starter N and P for Corn
Use of starter fertilizers for corn in the Southeast is less common than in the Midwest, but university research in Louisiana has shown that 4 to 5 gal. of 10-34-0 or 11-37-0 applied in-furrow can help get plants off to a good start and increase yields even on soils testing high in P. Wet conditions in the spring may cause soils to warm very slowly, restricting root development and plant P uptake. Starter fertilizer on such soils can remedy this problem, hasten canopy closure, lead to earlier maturity and grain harvest, and reduce grain-drying costs.

February 20, 2014 – N Timing for Warm-Season Forage Production
Several research studies have focused on whether it is better to apply the entire N rate in the spring, or to split the amount into two or more applications. Many of the results suggest that split applications are preferable when the total N rate exceeds 100 lb/A. Typically, the first 100 lb N/A is recommended to be applied in mid- to late-spring with the remainder applied later in the summer. The summer application is usually made following the first cutting or prior to an expected rainfall event. Even considering the additional application expense, the advantages of splitting more than 100 lb N/A usually outweigh the cost.

February 10, 2014 – N Fertilization for Non-Legume Cover Crops
For maximum soil moisture conservation and tilth improvement benefits from a non-legume cover crop, additions of fertilizer may be necessary. The P and K soil test levels required for high yields in the main cropping system should adequately meet the needs of any winter cover crop. But to ensure rapid fall growth, it is often recommended to apply 20 to 40 lb N/A at establishment. In mid-February, check the color of non-legume cover crops. If the grass looks pale green or if more growth is desired, another 20 to 30 lb N/A is usually recommended.

February 1, 2014 – Starter Fertilizer in Cold Soils
Starter fertilizer placed near the seed provides an abundant supply of P and K for crop uptake early in the growing season. Applying plant nutrients in the “Right Place” is especially important when crops are planted into cold soils. Cold soil temperatures slow down the movement of P and K, which can affect root growth, nutrient uptake, and ultimately yield. Typically, when soil tests indicate high P or K levels, a response to starter fertilizer is not expected. However, there are university data that show early spring-seeded crops, like potato, respond favorably to starter fertilizers when planted into cold soils even when soil test levels are high.

January 20, 2014 – Learn to Recognize Crop Growth Stages
Efficient fertilizer use involves applying nutrients at the right time during the growing season. Most often, this time will coincide with increased nutrient demand and uptake of the crop. Crop growth stage is a good indicator of in-season nutrient demand. Local extension agents and crop advisers can provide publications describing crop development and nutrient uptake. Whether it’s Feekes 5 in wheat, V6 in corn, or tuber initiation in potato, understanding uptake patterns and being able to recognize different growth stages in crops will help growers make better decisions regarding the “Right Time” to make their fertilizer applications.

January 10, 2014 – Calibrate Fertilizer Application Equipment
One of the best ways to begin improving fertilizer efficiency and profitability is to make sure that application equipment is properly calibrated to deliver the “Right Rate”. Both dry and liquid applicators need to be checked annually for wear and tear. Worn out augers, spinners, belts, tips, etc., can all lead to inaccurate rates. Contact your fertilizer dealer, crop adviser, or extension agent for calibration help. Take the time to do it now because you’ll be too busy in the spring and the risk of under- or over-fertilization is costly.

January 1, 2014 – Assessing Nutrient Use Efficiency
How productive is your cropping system relative to nutrient input? The simplest estimate is to divide units of crop yield or nutrient removal by units of nutrient applied. This method generates useful numbers for on-farm comparisons. However, the true efficiency of fertilizer-derived nutrients is not known because neither method considers inherent soil nutrient supplies. To answer the question: “How much of the applied nutrient was taken up by the plant?” one must have knowledge of crop yield without nutrient input. The use of a “zero-fertility” or “omission plot” has traditionally been limited to research settings, but could easily be established on the farm to be used to estimate nutrient use efficiency.

December 20, 2013 – What’s New in Soil Fertility?
The winter months are a great time to find out. Several universities and private companies sponsor workshops and schools early in the year geared toward certified crop advisers and growers. Topics covered often include current research results on rate, timing, source, and placement of plant nutrients. These programs are also good places to learn about the performance of new products and what is available for the upcoming season. Contact your local cooperative extension specialist or CCA for more information on upcoming educational opportunities in your area.

December 10, 2013 – Profitable Precision Farming
There are numerous precision farming tools available, but which ones will make growers the most money? The following five were identified as having good profit potential for corn production. (1) Computer queries – a good farm software package can help identify trends in soil test levels useful in monitoring long-term changes; (2) Auto-guidance equipment; (3) Yield maps; (4) Variable-rate technology – economic benefits to site-specific fertilizer applications have been shown for N, P, K, and lime; (5) Sensor technology – non-destructive, in-season diagnosis of nutritional disorders is the most promising use for remote sensing tools.

December 1, 2013 – Winter Nitrogen Applications for Wheat
Normally, winter N applications to wheat grown in the Southeast are not recommended. However, there are situations where a small application (30 to 40 lb N/A) in late December or early January might be beneficial. Conditions that may warrant a winter N application include significant leaching rainfall events in the fall, thin stands of pale green wheat, and expectations for several growing days (temperatures above 50°F) in early winter. The risk for N losses from winter fertilizer applications is great, so decisions to use them should be made only after careful consideration of field-specific circumstances.

November 20, 2103 – What are the Benefits of Yield Monitoring?
A yield map is an excellent way for growers to identify spatial variability in their fields that is affecting crop yield. Not every part of a farm needs to be managed the same and yield monitoring can help growers make better management decisions on a site-specific basis. Yield maps will not identify the reasons for variability, but lower yielding areas can be targeted for intensive soil sampling to discover the cause of the problem. Recognizing spatial variability can help growers ensure that all areas of their field are receiving appropriate rates of plant nutrients for optimum production.

November 10, 2013 – What is Buffer pH?
The lime rate required to raise soil pH is affected by initial pH, target pH, and the buffering capacity (BC) of the soil. Buffering capacity is the amount of reserve acidity in a soil and is affected by soil texture, CEC, mineralogy, and soil organic matter. A soil with a high BC will require more lime than a soil with a low BC to achieve the same change in soil pH. The buffer pH reported on a soil test is based on a laboratory method that estimates BC. “Soil pH” is the acidity of your soil. “Buffer pH” is only used to determine liming requirement and is not an existing feature of the soil solution.

November 1, 2013 – Soil Test Interpretation
Many soil test laboratories use a build-up and maintenance approach when making fertilizer recommendations. If a soil tests “low” for a particular nutrient, higher fertilizer rates will be recommended to build-up the amount of plant available nutrient in the soil. A “medium”-testing soil will also require a moderate build-up, usually a fertilizer rate slightly in excess of the maintenance requirement. Soils that contain “high” levels of plant available nutrients do not require build-up, but maintenance applications to offset crop nutrient removal should be made. “Very high” soil nutrient levels suggest that no annual maintenance treatments are needed, but nutrient levels should continue to be monitored using regular soil testing.

October 20, 2013 – Preplant Wheat Fertility – Nitrogen
Excessive fall-applied N can lead to increased susceptibility to lodging, disease pressure, and freeze damage in winter wheat. Nitrogen fertilizer applied in excess of the crop requirement prior to dormancy also creates the potential for winter leaching losses in the Southeast. However early-season, plant-available N is critical for strong root formation and fall tillering. Typically in the Southeast, 30 to 40 lb N/A is adequate for fall growth with the remainder of the N requirement topdress-applied in the spring. If the wheat is going to be grazed during the winter, fall N rates will need to be increased.

October 10, 2013 – Preplant Wheat Fertility – Potassium
Adequate K nutrition for winter wheat will result in plants that have greater resistance to moisture stress, more tolerance for some diseases, and greater straw strength that will reduce the potential for lodging. Like many other nutrients, K fertilizer rates should be based on a reliable soil test recommendation. Wheat in the Southeast will take up about 2 lb K₂O per bushel of wheat produced and 90% of the total K uptake will occur prior to heading. This makes the fall a good time to apply K fertilizer in combination with any needed P or N for winter wheat production.

October 1, 2013 – Preplant Wheat Fertility – Phosphorus
Phosphorus is essential for root development and uniform growth in winter wheat. Plants that don’t get off to a good start due to inadequate P in the fall won’t tiller properly and are more susceptible to winter-kill. Phosphorus fertilizer should be applied according to soil test recommendations or estimated crop removal. Wheat in the Southeast will take up approximately 0.67 lb P₂O₅ for each bushel of grain produced. Banding P with the seed is the most efficient application method at lower rates or soil test P levels, but is not essential for high yields as long as soil test P levels are maintained in the high range.

September 20 – Variable-Rate Fertilizer Applications
A common perception about variable-rate applications (VRA) is that total fertilizer rates will be reduced. This is not necessarily the case. The main advantage to using VRA is increased nutrient use efficiency (NUE). This increase in NUE is often due to reduced nutrient rates resulting in the same grain yield as a higher single-rate application. However, just as often, fertilizer rates don’t change, but the VRA results in higher grain yields by redistributing nutrients in the field according to plant needs. This will also result in higher NUE, which is an important part of a profitable and environmentally sound fertilizer program.

September 10 – Management Zones
Management zones can be defined as areas of a field that possess similar characteristics that may require varying degrees of management including fertilizer applications. Management zones can be identified using yield maps, aerial photography, satellite imagery, or various measured soil parameters. Several fields in the Southeast possess areas that vary significantly in yield potential in a given year. Treating these areas independently will result in a more efficient and profitable fertilizer program.

September 1 – Soil pH
Soil pH is one of the most important chemical factors affecting nutrient availability. Allowing soils to fall too far below the target pH for a specific crop can induce deficiencies of nutrients like P or result in Al toxicity in some crops like wheat. An optimum soil pH helps plants use nutrients and soil moisture more efficiently. If it has been several years since you limed, now is a good time to test the soil and take corrective action if needed.

August 20 – Was Weed Pressure Worse This Year?
If the answer is yes, it might be time to evaluate your soil fertility and plant nutrition programs. Poor fertility leads to thinner stands, less seedling vigor, and a reduced ability to compete with weeds for resources early in the growing season. Remember, herbicides, insecticides and other pesticides are “yield protectors”, but fertilizer is a “yield builder”.

August 10 – Leafspot in Cotton?
Leafspot in cotton is caused by fungal pathogens; however, the foremost problem could very well be K deficiency. Low concentrations of tissue K weakens leaf cells and makes them more susceptible to secondary pest problems like fungal infections. If the problem is detected early enough in the season (by the fourth week of bloom) foliar K applications may reduce negative yield effects. Unfortunately by the sixth week of bloom, not much can be done. Avoid these situations by establishing adequate fertility levels in the soil prior to planting or using an in-season leaf or petiole monitoring system.

August 1 – Late-Summer Forage Fertilization
You might have begun to notice some of your pastures running out of N. In many cases, very little fall growth will occur without a late-summer N fertilization. Even if fall growth is limited by rainfall shortages, there may be long-term benefits to N applied in August. These benefits include new root and tiller development that strengthen the plants over the winter and result in increased forage production the following spring.

July 20 – Fall Vegetable Fertilization
Now through mid-August is the time to plant fall vegetable crops in much of the Southeast. When growing high-value crops like vegetables, it is important to have the best information available. A current soil test report is a great place to start. Many vegetables are short-season, shallow-rooted crops that don’t mine the soil well for immobile nutrients like P and K and much of the crop requirement for these nutrients needs to be supplied through fertilizers. Considering the high-input costs associated with vegetable production, growers can’t afford to have guesswork as part of their nutrient management programs.

July 10 – Mid-Season Tomato Fertilization
For staked tomatoes transplanted in mid- to late-May, 35 to 40% of the total in-season N requirement will be applied in the next few weeks. Many trickle-fertigation programs are developed based on N needs, but K nutrition can not be forgotten during this time in the growing season. A good way to ensure adequate K nutrition is to use a 1:1 or 1:2 N-K blend like 7-0-7, 4-0-8, or 5-0-10 for in-season N injections. University research has shown that eliminating K from the fertigation program can significantly reduce yields even on soils testing high to very high in extractable K.

July 1– Baling Drought Stressed Corn
Baling corn for hay is a way to salvage some value from a drought stressed crop. Growers who select this option should have the crop evaluated for nitrates, particularly in corn that got big enough to sidedress. Unlike ensiling, in which fermentation generally lowers nitrate levels 35 to 50%, baling the crop will have no effect on stalk nitrates. Growers should contact a crop consultant or extension agent for instructions on proper sampling techniques and directions for field analysis or submitting the sample to a laboratory for testing.

June 20, 2103 – Crop nutrient uptake and removal
How many lbs of N did your wheat take up? How many lbs of N were removed in the harvested grain? What about corn, or grass, or tomatoes? With so many states in the region implementing nutrient management planning criteria that consider crop nutrient removal, it is becoming increasingly important that growers have a feel for nutrient uptake rates for their crops. Many people are surprised when they find out the actual quantities of nutrients required to achieve their target yields. Nutrient uptake and removal tables for most crops grown in the region are available on the IPNI website at nase.ipni.net.

June 10, 2013 – Lawn fertilization – N
Adequate amounts of N are necessary to maintain a healthy, green lawn. Like hay and pasture grasses, N is most efficiently utilized by splitting the N rate into multiple applications. For most lawn grasses, a typical recommendation is to apply 1 lb N/1000 ft² when spring growth begins and again in mid-summer. For thicker, greener grass, this application can be made on 2-month intervals during the growing season. Urea, ammonium sulfate, or any water-soluble N source can be used on lawn grass; however, over-application of N can result in leaf burning.

June 1, 2013 – Balanced fertility for bermudagrass production
The right balance of macronutrientsN, P, and K can contribute to several factors that lead to more efficient and productive bermudagrass systems. For example, P and K fertilization increase the percentage of N recovered in the harvested crop, which is directly related to protein content. Maintaining adequate levels of all nutrients increases rooting depth and reserves that are critical for rapid re-growth following harvest. Research in Georgia showed that soil water use is less following annual N-P-K applications compared to an unfertilized control (9.8 vs 2.7 inches/ton forage produced).

May 20, 2013 – Bermudagrass fertility – K
Bermudagrass will take up more K than any other nutrient, approximately 50 lb K₂O/ton forage. In the southeast, where yield potentials can be as high a 7 to 8 tons/A, K₂O requirements can approach 400 lb/A. Inadequate K fertility can result in plants that are more susceptible to diseases, like fungal leaf spot, early stand decline, drought stress, and winter-kill. Good soil testing and fertilization programs are the best way to monitor and maintain soil K levels.

May 10, 2013 – Bermudagrass fertility – P
Phosphorus is needed for photosynthesis, respiration, energy storage and transfer, cell division and enlargement, and many other processes in plants. A ton of bermudagrass forage will take up approximately 12 lb P₂O₅. So, a 7-ton yield requires 84 lb P₂O₅/A/yr. Following soil test-based recommendations is the best way to ensure that P fertility levels are adequate for bermudagrass production. Many soils in the southeast test high in P; however, continued nutrient removal without replacement can be costly. Maintaining adequate soil-test P levels and balanced fertility are critical for high quality bermudagrass forage production.

May 1, 2103 – Bermudagrass fertility – N
The goal in bermudagrass production is to produce a quality feed source high in protein and total digestible nutrients and good N management can help. A ton of bermudagrass forage will take up approximately 45 lb N. So, a 7-ton yield in the southeast will require about 300 lb N/A. Nitrogen should be split-applied for best results. Typical recommendations suggest applying 60 to 100 lb N/A when the grass begins to green up then an additional 60 to 100 lb following each hay cutting. For pasture, apply 60 to 100 lb N/A in the spring then an additional 40 to 60 lb after each graze-down.

April 20, 2013 – Tissue testing
By the time nutrient deficiency symptoms appear in the leaves, all other plant parts have been affected. Petiole or leaf analysis can identify nutrient deficiencies up to two weeks in advance of any yield reductions and can also be used to determine the need for sidedress or foliar nutrient applications. Contact your local CCA, fertilizer dealer, or extension specialist for instructions on proper tissue sampling. The best defense against nutrient deficiencies is a combination of soil testing, tissue testing, and proper fertilization.

April 10, 2013 – Side-dress N for corn
Spring in the southeast is often very wet, increasing the likelihood of N losses. Corn takes up less than 10% of its total N requirement early in the season, making it an ideal candidate for split N applications. The time when rapid vegetative growth (and the highest demand for N) occurs varies depending on regional temperatures; however, most recommendations suggest targeting somewhere around the V6 growth stage to make the in-season N application (typically 2/3 of the total required rate). Applying too much N early, particularly in a wet year, can reduce efficiency and be less profitable.

April 1, 2013 – Starter N in rice
Semi-dwarf rice cultivars have increased in popularity in the southern U.S.; however, emergence and seedling growth rates can be lower compared to taller cultivars. Starter fertilizer applications have proven to be beneficial in increasing early-season vegetation and sometimes yield in corn, cotton, and soybean and recent research indicates that rice responds favorably as well. Mississippi research data show that applying nitrogen at 20 lb N/A as ammonium sulfate or diammonium phosphate at the two-leaf stage can increase five-leaf stage plant height, which can have positive management implications such as earlier flood establishment. Starter N applications can also result in moderate grain yield increases compared to no starter application.