Summer 2008

Northcentral

Flooding and nutrient management
How does major flooding impact nutrient management? The following is a list of some considerations:

• Major flooding can erode some areas and enrich others. The soil profile that exists after a flood may not look like the profile that existed before. Soil testing is essential to see what nutrient levels now exist. Past history does not provide good guidance where major flooding has occurred.
• Flooding reduces the organic matter pool in soils and also leads to greater denitrification and leaching losses.
• Where severe flooding has occurred, fallow syndrome may occur during the next corn crop. This syndrome is characterized by a poorly developed root system, leading to reduced growth and nutrient deficiencies. Corn is most sensitive. To manage this syndrome, starter fertilizer containing P should be applied at planting.

Ontario and Quebec experienced a cool month of May. There were plenty of early planting opportunities for corn, but seedlings have grown slowly so far, especially in no-till. Ohio too reports delayed emergence of corn and soybeans and later heading of winter wheat than normal. The delay in crop development stage is not yet a concern for yield expectations. Environment Canada predicts a warm summer for essentially all of Ontario, Quebec, and the main agricultural areas of the Atlantic Provinces. Summer precipitation forecast for this region is mostly normal.

Many factors affect availability of N from the soil, from manures, and from previous crop residues. Mineralization rates, leaching and denitrification losses, and volatile losses of ammonia are all controlled by the weather. A soil nitrate test this month will be very helpful—but make sure the corn is at least 6 in. tall before taking it. Cornell University has been providing advice based on real-time weather data for interpreting this soil nitrate test. Taking account of the weather is an important component of N management. Ontario corn N recommendations take into account many factors – check out the N Calculator at www.gocorn.net

Soil Texture Affects Plant Nutrient Supply Capacity
Have you ever wondered why it is usually necessary to add more fertilizer to a coarse-textured sandy soil than a fine-textured clay-loam soil to grow equal yielding crops as long as moisture isn’t limiting? It all has to do with the size and volume of different sized soil particles contained in the soil.

Most soils used for cropping are called mineral soils. This means the soils are composed mostly of mineral particles originating from the weathering of rock deposits, although the topsoil of most soils contain some organic matter or humus originating from the decomposition of plant, animal, and microbial residues. The mineral particles in soils are grouped into three size classes based on particle diameter. The three classes and their range of sizes are sand (2.0 mm to 0.05 mm), silt (0.05 mm to 0.002 mm) and clay (less than 0.002 mm). Soils usually contain a mixture of these three classes of particles and can be separated into twelve particle size groups or soil textures based on the proportions of sand, silt and clay sized particles contained in a specific soil. For example, a loam textured soil could have almost equal proportions (e.g. 33.3% each) of sand, silt, and clay sized particles; a clay-loam textured soil could contain 25% sand, 25% silt, and 50% clay; and a sandy-loam textured soil could contain 70% sand, 15% silt, and 15% clay.

All these soil particles characteristically have a negative electrostatic charge on their outer surface. The greater the outside surface area compared to the mass of the particle, or the smaller the particle, the greater the inherent negative electrostatic charge per mass unit of soil. This negative charge has the ability to attract and retain positively charged ions or cations in the soil. This means that the greater the proportion or percentage of smaller particles in an equal weight of soil, the more cations can be attracted stored in a soil and be made available for plant growth. This means a soil containing mostly clay particles compared to a soil containing mostly sand particles will store more cations. Many of the cations in soils are mineral elements required for plants to grow and consist of the following plant nutrients: calcium, copper, iron, magnesium, manganese, potassium, and zinc.

An accepted way to describe the cation storing and plant supplying capacity of different soils is a laboratory determined measurement called cation exchange capacity (CEC). It is described in units as millequivalent cations per 100 g (meq/100 g) of soil. You can ask for a CEC determination when you send a soil sample to a soil test laboratory. The following table shows approximate ranges of cation exchange capacities of some different textural classes of soil.

Soil samples were taken from two different farm fields that were just 10 miles (16 km) apart but had different soil textures. The one was a sandy-loam (SL) textured soil (CEC of 4.4) and the other a clay-loam (CL) soil (CEC of 21.1). The amount of calcium (Ca), magnesium (Mg), and K in lb/A stored and yet available for release to crop plants in the two soils down to a 3.3 ft (1 m) depth were respectively 1,779 Ca, 579 Mg, and 252 K in the SL soil, and 16,860 Ca, 2,382 Mg, and 724 K in the CL soil. The CL soil contained and could supply about 10 times as much Ca, 4 times as much Mg, and 3 times as much K compared to the SL soil. (Source: soil samples collected near Strathmore, AB, and analyzed at Envirotest Laboratories Calgary, AB, author 1997). In practical terms, both soils would have adequate levels of Ca and Mg to grow a crop of irrigated alfalfa hay in the crop year after soil sampling, but more K would be required as fertilizer on the SL soil compared to the CL soil. In the long-term sandy soils need greater fertilizer applications compared to finer textured soils.

Conditions across the region are considerably mixed and in some cases extreme. For example, most of Nebraska, the central and eastern areas of Kansas, and eastern Oklahoma are wet, and in places detrimentally so. Meanwhile, most of Texas, New Mexico, and Colorado are rapidly and alarmingly in the process of drying. Wheat crop yield is also mixed for the region and in many areas has not been good due to dry conditions and in some cases delayed planting. However, in some parts of the region the wheat yields are good to excellent. Similarly, spring planted crop conditions are a real mixed bag.

Fertilizer prices continue to be a major issue for all crops. Questions about rates of application are certainly appropriate and common in this environment. An article concerning fertilizer price and economics for irrigated corn was recently prepared (in press) for an upcoming issue of Better Crops magazine. The article addresses irrigated corn fertilization and is based on work from the Southern and Central Great Plains region. Following are a few excerpts from this piece.

“ As crop price increases, the impact of increasing N fertilizer price on optimal rate of application diminishes…. In other words, N price does impact optimal rate of application, but that impact is diminished with increased grain price. Indeed, there is little difference in predicted optimal N application rate (for irrigated corn) at $3.50 corn and $0.25 N compared to $5.50 corn and $0.75 N… the difference is only 14 lb N/A. Granted, the outlay and risk involved in today’s environment is significantly higher than a few years ago, but the most profit producing N rate has not changed much.

 “The importance of balancing N with other nutrient inputs is often emphasized. One of the best ways to ensure the production of optimal yields and efficient use of N and other fertilizer inputs is through complete and balance fertilization. Results from a recent high-yield irrigated corn study (Gordon, 2005) in north central Kansas have demonstrated how balance among N, P, K, and S can impact yield. Nitrogen was kept at a constant and non-limiting level (300 lb/A) as P, K, and S were added… Using the response data from this example, and assuming that N cost is $0.60/lb, P2O5 is $0.90/lb, K2O is $0.50/lb, S is $0.80/lb, and corn price is $5.50/bu, a very simple analysis of return on fertilizer investment shows that N alone returned $211/A while the complete treatment (N+P+K+S) returned $533/A. Thus, even in a relatively recent price scenario, balanced fertility still has the potential to pay handsomely.

 “The addition of P, K, and S in the previous example obviously impacted how much of the applied N was utilized to produce yield… Recovery efficiency for the fertilizer treatments in this example was determined by estimating how much N was taken-up by the crop over the zero N control, assuming N uptake of 1.4 lb N/bu grain produced, then dividing that by 300 (lb N fertilizer applied). While this is a crude estimation, it nevertheless serves a purpose…. Compared to N alone, the complete program improved apparent N use efficiency by over two-fold, from 0.33 to 0.75. This is equivalent to more than doubling the “bang for the N buck” by simply attending to other nutrient needs.”

This article demonstrates that complete and balanced fertility still pays, even with today’s record prices. It is only one in a series of like articles that are being prepared for Better Crops, Issue #3, 2008. Look for this series at http://www.ipni.net/bettercrops

Wheat harvest is going well in the southeast region. Several states in the south are finishing and doublecropping is underway, while the northern states in the region are getting started. Yields are being reported as being better than expected to near record levels. There are a few problem spots such as too much water and a little freeze damage in places, but overall it looks like the 2008 wheat crop is going to be better than average. Much of the success of this year’s crop may be due to more intensive management. Dewey Lee, University of Georgia extension small grains specialist, addressed these management shifts at the Alabama Corn and Wheat Conference last winter. “Looking at Alabama and Georgia state yields, we have moved our yields up to a level that tends to be more profitable with the rising costs of inputs.” He noted improved N fertilizer practices, such as splitting N in the spring based on tiller density, as one of the ways growers are achieving higher yields.

Not to the extremes experienced last summer, but the southeast is dry. Many growers are becoming concerned about corn and others are waiting for moisture before double cropping soybean and cotton. There are reports out of Georgia of growers beginning to water up doublecrop cotton. Earlier planted cotton is between squaring and first blooms and looks pretty decent in most places. The concern surrounding cotton is that the downward trend in acreage in the region may continue if the price doesn’t begin to follow that of corn and soybean.

Colorado is hosting the prestigious 9 th International Conference on Precision Agriculture at the Hyatt Regency Hotel in the Denver Tech Center, Denver, CO from July 20 th – 23 rd, 2008.

Topics in the conference: There will be over 250 presentations (oral and posters) from scientists, practitioners, and industry personnel from over 30 countries around the world. Topics in the conference include but are not limited to:

• Guidance Systems, Auto-Steer and Robotics in Agriculture
• Profitability and Adoption of Precision Agriculture
• Remote Sensing for In-Season Crop Management
• Remote Sensing for Biomass and Grain Yield
• Sensor Technologies in Precision Agriculture
• Engineering Technologies in Precision Agriculture
• Precision Agriculture Applications in Horticultural Crops
• Emerging Issues (Energy, Biofuels, and Climate Change)
• Education and Training in Precision Agriculture
• Managing Spatial Variability in Soil, Crop, and Natural Resources
• Precision Conservation
• Traceability
• And many more….

Keeping with the tradition of the ICPA conferences, there will be five concurrent sessions each day of the conference. One among those will be a dedicated session called “A to Z Track” which is meant especially for crop consultants, advisers, agronomists, producers, extension agents, and other practitioners.

The A to Z track will have talks from experts and specialists in their respective disciplines. These specialists will present talks that will be applied in nature with relevant “take home messages” for practitioners and others. We have put together an excellent group of presenters for the A to Z track. The list of speakers and topics can be found on the web at http://www.icpaonline.org/presentations_az.php. Some of the featured topics this year include two sessions on “The Role of Precision Agriculture in BMPs”. Speakers will include university scientists, industry specialists, and growers presenting information relevant for several major crops. We will also feature two hands-on workshops. One workshop is titled “GreenSeeker on the Farm” and will include discussion of on-the-go, variable-rate fertilization using GreenSeeker optical sensor technology and demonstrations of how to use hand-held sensors to generate in-season N rates for a variety of crops. The second workshop will focus on new nutrient management software applications.

Discounted Registration Fees for Practitioners to attend the A to Z tracks:
For crop consultants, advisers, producers, extension agents and other practitioners, there is a reduced conference registration fee to attend the A to Z portion of the conference.

For one day registration (either Monday July 21 st or Tuesday July 22 nd): $150/day

For all-days registration (Monday July 21 st through Wednesday July 23 rd noon): $300

Please go to the conference registration website http://www.icpaonline.org/2008/registration/cb_RegistrationForm_Person.php and choose A to Z track for registration.

We are in uncharted territory for much of agriculture in Western North America. With the prices of farm inputs at an all time high, crop commodity prices whipping up and down, and water deliveries uncertain, the same advice still applies. Use sound management decisions to maximize your net return at the end of the season.

Applying fertilizer at the most economic rate does not guarantee a profitable crop. Profit is determined by the differences between total income and total expenses. Rising fertilizer prices will have the greatest impact on the profitability of the crops with the highest fertilizer demand, all other factors remaining constant. The relative profitability of various crops needs to be compared when crop selection decisions are made. Uncontrolled events, such as weather and global market conditions, also add to uncertainty. Every farm manager should consider input from agronomy and financial experts before making decisions about the investment of available capital. It may be wise in some circumstances to place orders for fertilizer with an eye on taxes, too.

Some producers are inclined to try short cuts to the well-established principles of plant nutrition. Essential plant nutrients are called “essential” because there is an absolute requirement for them in order for plants to survive. There are many techniques that can help growers get the maximum benefit from fertilizers, but these must be done thoughtfully and deliberately. If the soil has been analyzed and found to already contain adequate concentrations of nutrients, no additional fertilizer may be required for a period of time. The careful monitoring of soil nutrient concentrations allows this to be done without reducing crop yields.

As fertilizer prices increase, there seems to be a proliferation of new wonder products that claim to reduce or virtually eliminate the need for added nutrients. Many of these products are not field tested or independently evaluated. Often, where there is inadequate field testing, there is a potential for dishonesty and misrepresentation. Where dishonest practices occur, there is the possibility for the reputation of the honest dealer to be damaged, too. George Akerloff won the Nobel Prize in economics by explaining how the lack of solid information in the marketplace and the presence of ineffective products reduce the reputation and viability of even the good companies. It does not take an economist to know that you should find a trusted agronomist or consultant with whom you can establish a long-term relationship…someone who will tell you the truth in both the good and the lean years.

Use sound financial and scientific principles in making future decisions on how to nourish your crops. Use fertilizers as an essential input to improve your bottom line and maintain your financial security.