Back-to-Basics: Regional Updates Archive

This season’s corn crop is predicted to be the biggest on record at 13.4 billion bushels. Soybeans too are predicted to have a record high production of 3.4 billion bushels. Production for both crops is up 2% over last year. Crop development is also ahead of last year for both crops. As of Aug. 15, 75% of the corn was in the dough stage, compared to 38% a year ago. About 84% of the soybeans were setting pods by mid-August compared to 69% at that time in 2009.

These statistics indicate that farmers are expected to be harvesting a large crop much earlier than last year.Two nutrient management points to remember about this season:

See the following links from the USDA-NASS for more information about crop statistics:
http://usda.mannlib.cornell.edu/usda/current/CropProd/CropProd-08-12-2010.pdf
http://usda.mannlib.cornell.edu/usda/current/CropProg/CropProg-08-16-2010.pdf

A warm summer with plenty of rain is producing excellent crop potential for much of Ontario. The winter wheat crop produced average to good yields and good quality, despite late planting last fall and very little need for fungicide application. Expectations are high for the corn crop based on its early planting and the early onset of grain filling. According to Greg Stewart, corn extension lead for OMAFRA, silage harvest this year may begin in August, in contrast to last year when cool conditions delayed silage harvest into October.

Corn crop condition is rated 79% good to excellent in Michigan. Corn in Pennsylvania and Ohio is faring less well, with 52% to 62% rated good to excellent.

Corn yield forecasts by the USDA are down sharply in 2010 for Maryland, Delaware, and Virginia, as compared with 2009. The soil test summary report for 2010 is in preparation. Preliminary indications are that the distribution of soil test K levels has shifted downward substantially since 2005.

Soon forage plants will enter the critical fall growth period, during which they store the carbohydrates they need to survive the winter. Adequate K is essential for this carbohydrate storage. August is an excellent time to apply K fertilizers. Potassium is particularly likely to run short if previous harvests have been heavy. The amount to apply is an important decision. Make sure it’s based on a recent soil test. It’s also helpful to look at the analysis results for K if you’ve sent forage from earlier cuts this year to the lab. Calculating a nutrient budget – nutrients removed by previous harvests minus the amounts supplied in manures and fertilizers – can also help determine the right amount to replace.

Summer Fallowing and the Northern Great Plains

Much of east-central and northeast Saskatchewan crop land was not planted this year because of excessive and continuing spring rainfall. This area is normally planted primarily to annual crops such as spring wheat, canola, barley, field pea, and flax. Much of this land is now being fallowed. For example, in the Watrous to Humbolt area of east-central Saskatchewan less than 25% of normally harvested land was planted, and the remaining 75% of the land is now being fallowed.

Fallow is a term used to describe a farming technique of leaving a field unplanted for a growing season. Anciently, fallowing land once in every seven years was a tradition practiced by the Hebrew people to “rest the land”. In modern times, fallowing is still used primarily as a moisture conserving technique in semi-arid cropping areas. It is usually called “summer fallow” and is done to conserve sufficient moisture in the soil in order to grow a reasonably high yielding crop the following year. It is not uncommon to have a two-year crop-fallow rotation in these dry areas.

Summer fallowing has also been used in the Northern Great Plains (NGP) region, over the past years, as a means of controlling weeds, and mineralizing nutrients, primarily N from soil organic matter and crop residues to aid in crop production. The advent of selective herbicides for weed control, and use of inorganic fertilizers as a nutrient source have reduced summer fallowing use for weed control or for supplying nutrients. For example, in the NGP use of summer fallowing peaked in the early 1960s at up to 30% of land cropped to annual crops, and has been reduced to a present level of 11.5% (12.5 million acres) of total land used for annual crops (109.5 million acres) as reported in the latest available census data. For the states and provinces in the NGP, the percent of land used for annual crops that is summer fallowed is 27, 3, 3, 16, and 9% respectively for Montana, North Dakota, Manitoba, Saskatchewan, and Alberta. The driest areas where summer fallowing is used for moisture conservation are in northern and eastern Montana, southeast Alberta, and southwest Saskatchewan. In these areas, summer fallow is regularly used and it is well integrated in to the existing cropping systems.

However, when a farmer is forced to summer fallow land due to adverse weather conditions there may be some questions as to what to plant for the next crop and how nutrients should be managed. Some growers in eastern Saskatchewan are considering planting winter cereals, mostly winter wheat, even though they would normally plant spring seeded crops. Also, there is a question as to what rate of fertilizer to use for the subsequent crop after the unplanned year of summer fallow. Most of the farmers in the affected area apply fertilizer for their crops in two different ways. First, around 20% of them fall-apply N in the form of anhydrous ammonia injected to about a 4 in. depth in bands, and in the spring at planting apply the remaining P, K, S, along with some N, and any other required nutrients in the seed-row or starter blend. Secondly, around 70% of farmers apply all the fertilizer at the time of planting in a precision side-band operation about 1.5 to 2 in. to the side and about 1 in. below the seed row, usually using no-till or reduced tillage.

Under normal annual cropping, the rates of fertilizer used are based on crop removal nutrient amounts minus regular residual plant-available nutrients as determined through soil sample analysis or from area experience, plus nutrients mineralized from soil organic matter and previous crop residues. Thus, the nutrient rates in applied fertilizer are used to supplement crop nutrient requirements, so yields are not limited by nutrient availability deficiencies. However, when an unplanned year of summer fallow occurs there is some uncertainty as to what rates of fertilizer to use for the next planted crop.

The most appropriate way to assess residual nutrient levels is to take soil samples and have the samples analyzed. This is especially important on fields that have experienced excessive rainfall. Both N and S are very mobile in soil as the nitrate (NO3-) and sulfate (SO4-2) ions, respectively. These ions move with water that is leached through saturated soils, and can be moved either deep within the rooting zone of crops, or even below the normal rooting depth. This then requires that soil sampling depth be greater than normal. For example, usual soil sample depths are 0 to 6, or 0 to 12 in., with some sampling procedures including an additional depth of 6 to 24, or 12 to 24 in. respectively. However, after excessive moisture it may be helpful to sample to the whole rooting depth of the subsequent crop in three increments, i.e. 0 to 6, 6 to 24, and 24 to 48 in.

Another reason to accurately determine residual nutrients – especially N – is that under excessively wet soil conditions gaseous losses of nitrate-N can occur as soil bacteria requiring oxygen, normally obtained from air in the soil, use the oxygen in the nitrate ion and the remaining N is emitted from the soil into the air mostly as nitrogen gas (N2), along with some as nitrous oxide gas (N20). This loss process is called denitrification. These denitrification losses of N can be quite large. For example, if the farmer had applied the majority of fertilizer N in the fall previous to the planned planting, e.g. 90 lb N/A as anhydrous ammonia and then the next spring planting was not possible due to excessive rainfall, the majority of the applied N could have been lost as described above. The only way to accurately determine to what extent the N was lost and what proportion remains is through soil sampling and analysis. There is potential to add excessive N and other nutrient fertilizers if soil residual nutrients are not considered.

Unplanned summer fallowing due to excessively wet conditions during planting is an unfortunate event, but it does happen occasionally in the NGP. It is important to accurately assess residual nutrient levels before deciding on nutrient rates when fertilizing for the subsequent crop.

Moisture conditions across the SCGP region remain generally good. The latest Palmer Drought Severity Index shows most of the region as moist to extremely moist. The exceptions are most of Oklahoma, eastern Texas, and southwestern Colorado. At this reporting the state crop condition reports show well over 50% of crops across the region in the good to excellent range; however, these conditions along with soil moisture conditions are deteriorating rapidly in some areas due to recent extreme temperatures. Particularly noteworthy for the region is the potential for cotton production this year.

The Texas High Plains represents the largest cotton producing region in the world, and a combination of good moisture and relatively low acreage abandonment may result in a record (total) crop for the region given continued favorable growing conditions.

Preparation of wheat ground is well underway in some areas. As we consider wheat fertility for the 2010-11 crop, remember that in addition to N, P, and other nutrients, chloride (Cl-) may be beneficial to wheat. Following is text from a recently prepared Plant Nutrition TODAY newsletter (“Considering Chloride for Wheat”-) that covers the basics of Cl- on wheat.

Chloride has been formally recognized as a plant nutrient since the 1950s. It is classified as a micronutrient, but plants may take-up as much Cl- as secondary elements such as sulfur (S). Concentrations of Cl- in wheat ﬂagleaf and corn earleaf at ﬂowering are commonly in the range of 0.25 to 1%.

Chloride is involved in several important roles in plants, including,

Chloride is an anion and is therefore mobile in the soil. It can be leached from the soil profile where internal soil drainage is good. Chloride may be supplied to soils from several external sources, including fertilizer input, atmospheric deposition, and irrigation water. Thus, low soil Cl- level is favored where: 1) there is limited application of Cl--bearing fertilizer such as muriate of potash (KCl); 2) where there is low atmospheric Cl- deposition (deposition is highest in coastal regions and decreases inland), and 3) in non-irrigated conditions. These conditions are met across much of the Great Plains.

Response of wheat to Cl- fertilization has been observed throughout the Great Plains from Texas to Canada. Much has been reported over the past 20 years or so on work from this region. A recent update and summary of chloride work in Kansas was published in a 2009 Better Crops magazine article (Vol. 93, No 4). It is generally accepted that there is little difference in performance among Cl- sources on winter wheat, and that topdress and preplant applications are effective. However, where there is potential for leaching, topdress application in the spring may be advantageous.

Increases in wheat yield from Cl- fertilization are usually due to either a classical nutrient response and/or suppression of fungal diseases. Under low soil Cl- conditions, some varieties may exhibit Cl- deficiency symptoms, sometimes referred to as physiological leaf spot syndrome. These symptoms are similar in appearance to tanspot or septoria, but are not caused by a pathogen. The absence of leaf spotting does not always mean that Cl- is not deficient since spotting is dependent upon wheat variety. Chloride has been shown to reduce the severity of several root and foliar diseases. In one Texas study, leaf rust infection of the ﬂag leaf was reduced from 68 to 27% by topdressing with 40 lb Cl-/A as muriate of potash.

Whether or not wheat will respond to Cl- usually depends upon soil Cl- level, disease pressure, plant Cl-, and variety. Response to Cl- is likely when soil Cl- levels are less than 45 lb/A from 2-ft. deep soil samples. Kansas State University recommends 10 lb Cl-/A application when the soil level is 30 to 45 lb/A, and 20 lb application when soil level is below 30 lb/A. It has been shown that some varieties are much more responsive to Cl- than others.

Chloride response in wheat can ultimately be expressed in terms of increased yield, higher test weights, and greater kernel plumpness. Therefore, it is worth considering the need for Cl- on the upcoming wheat crop.

In the last update, the outlook for rice in the region was very positive with one-fourth to one-third of the crop being rated as excellent. Now that harvest has begun in the southern-most states, we are still anticipating a very good crop. At the writing of this update, Louisiana was about 20% harvested, Mississippi was just getting underway and Arkansas was about 50% ripe. Ratings remained 45 to 60% good and 20 to 30% excellent. Early yield reports also indicate a good year for rice. Corn harvest is also moving along. Yields are quite variable across the region, largely due to rainfall. Much of the irrigated corn is yielding 200 bu/A; however, the dryland crop is ranging from 20 to 200 bu/A.

As is typical for the Southeast, we experienced everything this summer from drought in some areas to floods in others. The recent string of high heat has advanced the cotton crop faster than many expected. Rainfall in the past couple of weeks that might have helped in many years may have been too late to do much good for the crop this year.

A topic that seems to resurface each year as we head into the fall is regarding fertilizer reserves. Much of the concern began with the price spike in 2008, when people began to wonder if some of the change in price was due to a shortage of material. In response to these concerns, Dr. Paul Fixen prepared an article for Better Crops (2009, No. 3) on world reserves of fertilizer materials. While the estimates involve a great deal of uncertainty, the reserve base life reported in the article for P and K was 291 and 510 years, respectively. So, while we are not in danger of running out of P or K anytime soon, these are non-renewable natural resources and our attention to appropriate stewardship is critical. Dr. Fixen also noted that nutrient costs will likely rise over time as the most easily extracted materials are consumed. However, continued development and implementation of fertilizer BMPs that improve fertilizer efficiency and effectiveness can help slow the increase in fertilizer costs.

To learn more about nutrient stewardship and BMPs for southern cropping systems, as well as hear an update on fertilizer reserves, consider attending the 2010 Southern Plant Nutrient Management Conference that will be held in Olive Branch, Mississippi, on October 5-6, 2010. Certified Crop Advisers are encouraged to attend all of the sessions on Tuesday afternoon and Wednesday morning for extra (CEUs) in soil fertility and plant nutrition.The site of the conference will again be The Whispering Woods Hotel and Conference Center, http://www.wwconferencecenter.com. A block of hotel rooms has been arranged at the hotel, under the name “Southern Plant Nutrient Management Conference”. Conference registration will remain the same at last year, $50, and is payable upon arrival.

Boosting Efficiency
As the growing season winds down, it is time to finish up the last chores needed to produce an abundant and high-quality crop. All the decisions made during the season come together during harvest, when it becomes evident if the choices were correct or not. Next comes the step of getting the crop sold and making sufficient profit to stay in business. All of these steps rely on the principle of efficiency. One simple definition of efficiency is the ratio of output to the input. We apply this concept in many everyday decisions when we ask ourselves… is this worth it?

Getting the most efficient use of plant nutrients is a primary goal each year, but the same objectives also apply to efficient use of water, energy, pest protection, labor, and many other operations around the farm. As harvest season proceeds, use this time to evaluate your decisions and ask yourself if you have done all you can to optimize efficiency this year.

It is obvious that adequate plant nutrition is essential for growing healthy crops, but it must be supplied with an eye on efficiency. A convenient way to begin improving fertilizer efficiency is to remember the “4R” nutrient stewardship concept, which is applying the Right Source, at the Right Rate, at the Right Time, and at the Right Place. Reviewing these four principles will go a long way in helping improve the return on your fertilizer investment.