Fall 2004

Northcentral

Soil fertility: isn’t it pretty much the same old thing? Really, how many times do we need to conduct a fertilizer rate study? After decades of research and experience, don’t we generally know what to do already?

What this line of thinking fails to recognize is that soil fertility is moving into new dimensions. What do we mean? Here are a few examples that illustrate how plant nutrition is being approached today.

New dimensions to setting yield goals
Yield goals: they’re building blocks for most nutrient recommendation systems; but how do we set them? For years, the traditional approach has been to average together what fields have historically produced and add a little extra to future estimates. Does that approach accurately predict what an area is capable of producing?

A new decision-aid, called Hybrid-Maize, has been developed by the University of Nebraska that allows farmers and advisers to estimate the corn yield attainable at a particular site. This user-friendly software tool adds new dimensions to setting yield goals: planting date, hybrid maturity, plant density, and local weather data. This model has primarily been evaluated in the Corn Belt. It is available at: http://www.ianr.unl.edu/hybridmaize.

New dimensions to fertility assessments
Soil test results have traditionally been evaluated in three dimensions: latitude, longitude, and time. Taking samples at various places within fields and tracking fertility changes over time have been the most common practices; but current research is evaluating the importance of a fourth dimension: depth. How important are fertility levels in lower parts of the soil profile? Is there a maximum amount of nutrient stratification that can occur? Does the amount of fertilizer needed to change soil test levels by a given amount differ with depth? How does root distribution relate to the distribution of fertility in the soil? All of these questions are being actively researched in the Midwest. Some recommendation systems, like those in Minnesota and Iowa, have already incorporated guidelines for deeper placement of nutrients where reduced tillage systems are adopted.

New dimensions to nutrient recommendations
Yield and soil test levels: two basic components of most nutrient recommendations. In the past, the objective of most fertility research was to summarize a diverse set of data into recommendations that worked well, on average, for a given state. The recent trend in fertility research, however, has been to include new dimensions to nutrient recommendations: soil series, mineralogy, and mineralization potential. A recent example is research from Iowa that shows how corn grown on different soil series responds differently to potassium and requires a different set of interpretation classes. The movement toward a more mechanistic approach to making recommendations holds promise that recommendations can become as site-specific as the samples on which they are based.

Another approach to creating more site-specific recommendations is the development of localized data sets of response information, nutrient removal coefficients, and/or soil buffer capacity. Such data sets can become valuable resources for dealerships and their customers.

New dimensions to interpreting laboratory test results
In the past, a phosphorus (P) soil test result was a P soil test result. The person in the field didn’t care about how that P was measured in the lab. But today, with the advent of new laboratory analytical techniques, not all P test results are the same. Phosphorus measured by inductively coupled plasma emission spectroscopy (ICP) detects more P from a given sample than does the traditional detection method. New laboratory procedures add a new dimension to interpreting soil test results. For more information, see Better Crops 2004 #2, available at: http://www.ppi-ppic.org/ppiweb/bcrops.nsf.

New dimensions to environmental impacts
Environmental consequences to nutrient management decisions have always been present, but greater recognition of them has emerged in recent years. Nitrogen management focuses now not only on reducing leaching losses, but gaseous losses as well. New assessment tools, such as the P Index, may help identify hot spots where P management practices need to be altered to reduce environmental losses.

Are WE multi-dimensional?
The new dimensions in soil fertility challenge all of us to re-think our traditional approaches and work outside our comfort zones. Nutrient management can easily be treated as one-dimensional, but it is in the other dimensions that new opportunities for increased yield, environmental protection, and profit exist. Organizations like the Foundation for Agronomic Research play a critical role in providing universities, government organizations, and private industries with the resources they need to discover and investigate these and other new and promising dimensions.

Despite good yields, the enthusiasm of winter wheat growers in Ontario, Michigan, and New York has been dampened by harvest problems: high moisture levels, sprouting, and Fusarium. Wheat acreage may not expand much this fall.

Corn in both Michigan and Ontario is slightly behind normal in development, but not as far behind as last year. Much of the early planted corn in Ontario looks very good. Ohio and Pennsylvania corn is ahead of the normal for the past four years. Corn rating good to excellent is 86% in Pennsylvania, but only 60 and 52% in Ohio and Michigan, respectively.

Forage yields have been good, and some excellent hay has been made this year. Soon forage plants will enter the critical fall growth period, during which they store the carbohydrates they need to survive the winter. Adequate potassium (K) is essential for this carbohydrate storage. August is an excellent time to apply potash. 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, and supported by forage analysis as well. Calculating a nutrient balance – 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.

It’s estimated that about 1,200 large livestock operations in Ontario will be required by regulation to submit nutrient management plans next year. Because of the large workload, it is anticipated that the deadline may be pushed back from July to December.

The Quebec Fertilizer Manufacturers Association is meeting with the province’s Ministry of the Environment in August to discuss the benefits of using a Phosphorus Index as a risk assessment tool.

Several dealers in Ontario are testing the optimum rates of nitrogen derived from the new Ontario Corn Nitrogen Database. We anticipate sharing results in meetings this fall and winter.

The Canadian Fertilizer Institute’s Eastern Canada Agronomy Workshop, scheduled for 1-2 September in Cornwall, Ontario, features speakers from Ontario, Quebec, and New York, dealing with a range of topics pertinent to soil fertility. See www.cfi.ca for details. Proceedings will be available.

When to sample is a question asked each fall, especially where fall fertilization is practiced. While traditionally the recommendation has been to wait until soil temperatures drop below 50C (410F) before sampling, recent research in the northern Great Plains has found that soil nitrate-N levels may not be as variable as once thought. Little change was found in soil N levels in cereal stubble fields between mid-September through freeze-up in November, with little fall nitrate accumulation. Where waiting pays is in those fields where more N is generally released in September, such as pulses, canola, corn, or potato stubble. Delaying sampling in these fields is a benefit. Soil phosphorus and potassium levels generally are not affected by sampling date.

Wheat planting is just around the corner. With the relatively good soil moisture conditions, growers should make sure that nutrient inputs do not limit early season wheat growth and crop yield potential. Consider, for example, that phosphorus (P) affects wheat growth throughout the season in several ways. It’s a key factor in seedling development, and enhances early season adventitious root development. Sufficient P results in an early proliferation of tillers, increasing forage and grain yield potential. Good P fertility is also associated with greater nitrogen (N) and water use efficiency, improved winter hardiness, and earlier and more uniform maturity. Producers should make sure that the upcoming wheat crop is poised to make the most of what is starting-off as a favorable production year for winter wheat. Adequate and complete nutrition is necessary to optimize production and get the most yield (forage and/or grain) out of every inch of available soil water.

Fescue hay harvests have been delayed and summer perennial and annual grass hay harvest have been challenging because of relatively frequent rains in early summer. Livestock producers and hay purchasers will want to consider forage nutritive analyses to ensure that the total and digestible nutrient levels are in the desirable range. High hay yields will require attention to appropriate fertilizer rates to replace harvested nutrients.

In some states, cotton is ahead of normal because of the favorable moisture and heat unit accumulation (e.g. bootheel of Missouri). In parts of the Midsouth where rains and clouds persisted, some fruit shed occurred, and resulted in “fruiting gaps” and will cause a delayed harvest. We have received a number of calls asking about actions to correct nitrogen, potassium, and sulfur deficiencies in cotton. Leaching rains and increased dry matter production surfaced a number of nutrient imbalances

Early maturity (Group 3 and 4) soybeans were close to harvest, or being harvested in parts of Mississippi and Arkansas the first week in August. Pod development and seed filling was at or slightly above the five-year average in virtually all southeastern region states.

Corn and sorghum harvest has just beginning in Louisiana and Mississippi. Other states like North Carolina are a short time away from corn harvest, since the corn is predominantly in the dent stage. The harvest in Georgia is 10% complete.

Rice yields (first harvest) were disappointing in Louisiana, where rains exacted a larger toll than expected on the 38 percent of the acreage that has been harvested so far. Fields are starting to be drained in Arkansas and Mississippi in preparation for dry down and harvest.

Peanuts were looking generally good in the southeast. With the drier conditions, many fields are being irrigated in Georgia. The crop prospect appears to be similar to last year’s harvest.

Temperatures hit record lows in parts of Arkansas the last half of July, they rebounded again, followed by another brief period of relief, and then recoiled into the high 90’s again. The crops may be as confused as the farmers!

The coastal areas of North Carolina and South Carolina were being impacted by hurricane/tropical storm Alex. High humidity and very hot temperatures followed.

The majority of the peaches have been harvested in Georgia and South Carolina.

It was difficult to protect melons from pests this year because of frequent rains. The weather caused some farmers to miss their targeted harvest and market dates, and significant economic losses were reported by some. Disease pressure is reportedly high in remaining vegetable and fruit fields.

Sugarcane is in mostly good to excellent condition in Louisiana.

Some concerns have been received about the availability of potash for fall applications. There have been some reports that deliveries may not occur until November because of reduced inventory and transportation challenges.

A few crop highlights from the west:

Cotton:
This season is shaping up to be the best cotton crop in California in many years – maybe in several decades. Near perfect planting conditions and equally ideal growing conditions are largely responsible for this high potential. Cotton plants appear to have even better root systems and heavier boll set than in 2002, when 4 bales/A cotton yields were not uncommon. Both industry and government funding has been recently channeled into university research to refine and improve cotton fertilizer recommendations. A late-season decline frequently observed in previously healthy cotton appears to be alleviated by the presence of high levels of soil potassium (K) or with supplemental foliar applications of K. If this year’s crop sets a new yield record, much of the credit will be due to Mother Nature, with help from improved nutrient management.

Alfalfa:
Alfalfa is the most important forage crop grown in the West, with over 35 million tons produced annually! With higher hay prices this year, it is important to take care of your alfalfa fields before the cold weather of winter arrives. Plants take up needed phosphorus (P) and K during the autumn to help with enhanced winter survivability and improved regrowth next spring. More information can be found at: www.ppi-ppic.org/fallfertilization.

Grapes:
Close to one million acres of grapes are grown in the West. Fruit condition and yield are both expected to be good this year. World-class wine grapes, table grapes, and raisins all require different fertilization strategies. The one consistent factor is to know what it takes to get superior quality and quantity grapes and then carefully follow that recommendation.

Nuts:
The large acreage of California nuts (almonds, walnuts, and pistachio) looks on track for a good harvest. Almond yields are expected to top one billion pounds again, for the third consecutive year. Pecans and hazelnuts in other states appear to be headed for an average year. The quantity of plant nutrients removed in harvested nuts is commonly overlooked. For example, almonds in the shell remove 130 lb N/ton, 50 lb P2O5/ton, and 170 lb K2O/ton. It is important to provide adequate nutrition in order to sustain the long-term productivity of these perennial crops.