Fall 2009

Northeast
Crop condition ratings for corn, soybeans, and hay are much better this year than last in Ohio and Pennsylvania, but not quite as good in Michigan. In Ontario and Quebec, the growing season has been cool and rainy, with difficult harvests for hay and wheat. The month of July was particularly cool, setting several records. Ontario corn tasseling and silking has been delayed to early August, raising concerns about the crop maturing on time.

Ontario winter wheat yielded 5 to 10 bu/A below past averages, and varied from 40 to 135 bu/A. According to the 6 August Ontario Field Crop Report by OMAFRA Field Crop Specialists, “drainage, planting date and seed-placed phosphorus fertilizer are the three key elements responsible for these yield disparities.”

Prices this past spring led many to cut back on fertilizer use, particularly for K. Consequences may or may not have shown up in this year’s crop, but will eventually impact soil test levels and the performance of future crops. Have a look at the IPNI article — What Are the Consequences of Not Maintaining Soil Potassium? — for details.

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. For harvested cereals underseeded to forage, K should have been supplied at planting, but if it wasn't, applying as soon as possible after cereal harvest will ensure the seedlings develop into winter-hardy plants.

Manure applications following harvests of cereals and silage corn should be guided by soil tests and manure nutrient analysis. Rates should be appropriate to supply the soil's needs for P, K, and organic matter. Avoid wasting N by ensuring a cover crop grows to absorb what is released from the manure.

The 2009 crop season in the Northern Great Plains (NGP) started off with a delayed spring due to cooler than normal temperatures during March, April, and May. This delayed planting of spring-seeded crops, and has delayed the growth and maturation of fall-seeded wheat. The moisture received over the NGP region (the states of Montana, North Dakota, and the provinces of Manitoba, Saskatchewan, and Alberta) has been patchy. Some areas have had adequate moisture for above normal crop growth, some areas were so wet during planting of spring crops that planting was delayed and in some cases not possible. In other areas, the spring weather was not only cooler than normal, but very dry. Crops were planted into seedbeds with marginal moisture for germination and emergence, the result was that crop emergence was poor, substandard plant stands initially emerged. Then when later precipitation was received, a second or even a third wave of crop germination and emergence occurred, causing crop stands of various stages of maturity. This means that crop yields and time of maturity and ripening is unusually variable over the NGP.

It is important to take into account the type of growing season received when planning next year’s crops. In most cases, growers plan for an average to somewhat above average yielding crop and manage the plant nutrient supplies accordingly. However, in such a variable weather year it is important to understand what happened in your local area and adapt next year’s fertilizer plans based on this year’s weather and crop growth. When above average crop growth is experienced, nutrient levels in the soil are somewhat drawn down and usually necessitate greater than normal fertilizer inputs the following year. Conversely, when moisture and heat is limited, crop growth is less than normal, and more nutrients remain as residual in the soil – usually meaning some reductions in fertilizer inputs the next year. Fortunately for those growers who have experienced an average growing season with ample but not excessive moisture and heat, crop yields will be close to average and levels of residual nutrients will also be near normal. Chances are, fertilizer applications the next year will be close to average for the area farmed.

Whether a grower has had an above average, below average, or average crop yielding year, one of the best methods to determine residual nutrients in the soil is to have soil samples taken and analyzed. This can be done in the fall or spring, but fall soil sampling allows more time for planning and deciding what rates of nutrients to apply in the fertilizer blends for next year’s crop. By changing fertilizer rates, whether up or down from average amounts, a grower can better supply the needed amount, thus avoiding over or under fertilization.

Preparation for winter wheat planting is well underway. As we move toward the fall season, m ake sure appropriate early wheat fertility is in place to take advantage of the relatively good soil moisture conditions in parts of the region. Remember that wheat is very responsive to P fertilizer and that adequate early season P helps set ultimate yield potential. Soil test data, field history, and consultation with local professionals can help establish appropriate P rates. Also, make sure that enough N is available early in the season. While large amounts of N are not required in the early stages of growth, adequate amounts are essential for development and setting the stage for the remainder of the season. Where N is short early in the season, root development can be severely hindered, resulting in negative consequences for the remainder of the season. Ultimately the best N rate and timing decisions are region and field specific, but a general equation for N rate for winter wheat grain production is [ (Yield goal x 2.4) - (NO3-N lb/A 2 ft.) - (10 x %OM)].

One of the projects that the IPNI Spatial and Temporal Variability work group initiated this year was a "Top Ten" list of reasons why understanding variability is important when making nutrient management decisions. The work group (representing China, India, and North and South America) wanted to share different perspectives and feedback from production systems around the world to define a global set of topics that will be the focus for a series of deliverables to be developed over the next couple of years.

Counting down, the list looked like this:

Understanding spatial and temporal variability is important…

10) to guide technology development
9) for more accurate modeling
8) for cropping system sustainability
7) to guide nutrient management legislation
6) to maximize productivity
5) to maximize profit
4) to minimize environmental impact
3) because this year is not last year
2) to develop nutrient recommendation systems at the appropriate scale
1) for making the right management decision

The first product developed was a slide set presented at the recent InfoAg 2009 conference by Dr. Steve Phillips, Southeast Region Director. The talk was recorded and published by a precision agriculture website and can be heard at http://www.precisionpays.com/2009/07/infoag-talk-understand-nutrient-variability/.

Finally, a reminder that the 2009 Southern Plant Nutrient Management Conference will be held in Olive Branch, Mississippi, on October 6-7, 2009. This year, we will feature a session on nutrient drawdown on southern soils. Presentations will be given by university scientists discussing the effect over time of reducing or eliminating P or K fertilizer applications on soil test nutrient levels and rice, soybean, wheat, and corn grain yields. 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 – US$50, payable upon arrival.

The fundamental steps for a successful harvest begin with maintaining an adequate nutrient supply to nourish the crop. There are no substitutes to this basic foundation! During harvest, consider the quantity of nutrients that are being removed from the field and how best to replenish this nutrient reservoir this fall or spring. If you want to reconsider your current practices, consult with a Certified Crop Adviser to determine the Right Source, Right Rate, Right Time, and Right Place for your specific fertilizer practices. While headed for harvest this fall, keep your eye on the fundamentals to maintain success.