There are three main reasons for discrepancies in SCN resistance ratings between the seed companies and K-State:

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1 Number 15 January 10, Soybean cyst nematode resistance ratings 1 2. WRAPS watershed protection projects in Kansas 2 3. The profile nitrogen soil test can pay big dividends 4 1. Soybean cyst nematode resistance ratings Evaluating soybean varieties for soybean cyst nematode (SCN) resistance is a timeconsuming process. Every year, Tim Todd, K-State nematologist, screens all varieties entered in the Soybean Performance Test for SCN resistance. The results can be found on the web at: Producers may notice that the SCN evaluations conducted by K-State do not always correspond well with the resistance ratings provided by the seed companies. Why is this? Seed companies make a good faith effort to provide the most accurate rating they can, but those ratings still might not correspond to the results of the screening tests by K-State. Seed company ratings are usually provided by the original breeders, and are assumed to be accurate. Those who market the varieties do not normally have the time or expertise to double-check the breeder ratings and verify their accuracy. There are three main reasons for discrepancies in SCN resistance ratings between the seed companies and K-State: * The population of SCN used by the seed company breeders in their screening for resistance may not be quite the same as the population used in the K-State screening, even for the same race of SCN. * The seed company may be using ratings from breeders that are based assumptions rather than actual screenings. In other words, the company may assume that because the two parents of a new variety have SCN resistance, that the progeny will also have resistance -- without actually screening the new variety to make sure the resistance came through in the cross. 1

2 * In a few cases, the seed company ratings may be based only on field observations, such as yield response or visual symptoms, which may or may not reflect true genetic resistance. The first reason often causes some confusion. Race is a widely used, but misapplied, term in regard to SCN. A given race of SCN will not always behave the same. In the K- State evaluations, each variety is screened against a field selection from Kansas of Race 3 of the SCN. This is the most common race found in Kansas. It is often assumed that all Race 3 populations are the same, but that s not quite true. A Race 3 population from a field in Kansas may not be exactly the same as a Race 3 population from a field in Illinois, or even from another field in Kansas. There are some significant variations among different populations within the broad category of Race 3. Some populations will be more virulent than others on varieties rated as resistant to Race 3. Whatever the reason for any discrepancy between the K-State rating and the seed company rating, producers in Kansas should rely primarily on the K-State rating. The reaction of varieties to the Race 3 population used in the K-State screenings is a more reliable indicator of how varieties will perform in Kansas than the ratings supplied by seed companies. Producers should consult the K-State ratings when selecting varieties to plant on SCN-infested fields. Most varieties have the same source of SCN resistance: PI This genotype should give some level of resistance to most populations of Race 3 SCN. There are also other races of SCN present in the Midwest, including Kansas: Race 1, Race 4, and Race 14. These races are not as widespread as Race 3. There are two other genetic sources of SCN resistance used in commercial soybean varieties: PI (Peking) and PI (CystX and Hartwig). Peking does not offer much better resistance overall than PI However, CystX and Hartwig type resistance, derived from PI , can provide good resistance to nearly all populations of all races of SCN. -- Bill Schapaugh, Soybean breeder wts@ksu.edu -- Tim Todd, Nematologist nema@ksu.edu 2. WRAPS watershed protection projects in Kansas 2

3 K-State Research and Extension will join KDHE, the Kansas Water Office, State Conservation Commission, and other agencies in sponsoring the 2nd Annual Watershed Restoration and Protection Strategy (WRAPS) Conference, January 26, 2006 in Salina. What is WRAPS? In a nutshell, WRAPS is a planning process to identify all the water quality protection and restoration needs of a watershed. WRAPS serves to integrate TMDL implementation, water quality restoration, water quality protection, Source Water Protection, and Wellhead Protection activities required under the Safe Drinking Water Act and habitat restoration and protection activities. WRAPS was unveiled in 2005 as the new framework for watershed planning and management in Kansas. WRAPS is a locally-driven process of engaging watershed residents to determine the condition of water and other natural resources; identify sources impacting these resources; establish restoration and protection goals; identify restoration and protection measures (BMPs and other actions); and to develop an action plan to implement selected measures. The overall goals are to restore and protect the health of water and other natural resources in a watershed; better coordinate local, state, and federal restoration and protection efforts; and to more efficiently target technical and financial assistance programs within watersheds. Many K-State Research and Extension faculty, staff, and county agents are currently involved in supporting WRAPS projects around the state. Other agencies cooperating in WRAPS projects include KDHE, Kansas Water Office, State Conservation Commission, NRCS, and others. Typical outreach activities of the Extension personnel involved in a WRAPS project include: * Get local leaders and the general public involved in finding practical solutions to local water quality problems * Holding meetings on watershed water quality protection issues * Writing newsletters or newspaper columns on watershed water quality protection issues * Tour local point-source and nonpoint source problem areas * Monitor water quality in local rivers, streams, and lakes Agents and watershed specialists in other watersheds can help initiate a WRAPS project. To find out more about this, attend the conference on Jan. 26 or contact Dan Devlin ( ) or Robert Wilson ( ). -- Dan Devlin, Environmental quality specialist ddevlin@ksu.edu -- Robert Wilson, Office of local government rmwilson@agecon.ksu.edu 3

4 3. The profile nitrogen soil test can pay big dividends The soil can be a good provider of nitrogen (N) for plant growth. Through the process of organic matter mineralization, some soils can provide significant amounts of N for plant growth under certain conditions -- even up to 100 percent of crop requirements occasionally. When especially strong mineralization occurs, yields may be surprisingly good for the amount of N applied. Under other conditions, the same soil may not provide as much N for plant growth as expected. Soils with low organic matter have very little potential to provide N for plant growth under almost any conditions. This variation in mineralization rates from year to year, and from soil to soil, is one reason that making N recommendations for non-legume crops is an inexact science, at best. How do the soil fertility specialists at K-State go about developing a sound N recommendation for producers corn, grain sorghum, wheat, forage, and grass crops? The K-State N recommendation equation includes both organic matter levels and a profile test for nitrate-n (PNST) as important factors. To understand how the equation works, it s necessary to know how N exists in the soil and how it is supplied to plants. The majority of the N in the soil is in the organic fraction including organic matter, undecomposed plant residue, soil microbes, etc. This N is unavailable for direct plant uptake until it is microbially mineralized into the inorganic forms of ammonium or nitrate. The rate of mineralization, or release, is quite variable, depending on climate and cultural conditions. Therefore, organic matter measurements alone are not enough to be able to predict the N-supplying power of a soil before the growing season begins. Soils also include a variable amount of N in the inorganic form either attached to clay particles as ammonium or in soil solution. The amount of residual inorganic N in the soil often depends on factors from the previous growing season, such as past N fertilizer and manure application rates, mineralization rates, and plant uptake. The residual inorganic nitrate-n in the soil is measured by the PNST. The PNST test measures nitrate-n in the soil at the time of sampling. It is a measure of plant-available N, but only for a single point in time. Conditions before and after the sample is taken can have a marked influence on the accuracy of the PNST. Soil samples for PNST analysis should be dried soon after collection, within 24 hours, to minimize mineralization release from organic matter. Sampling to a two-foot depth is recommended for the PNST test since nitrate-n is a mobile nutrient and can easily move down from the surface 6 inches into the soil profile. The PNST test will not measure the N released by a prior legume crop because the N supplied by the residue of these crops must be converted through mineralization to ammonium-n or nitrate-n before it is available to plants. 4

5 The PNST test is especially recommended for fields where prior N fertilization or manure application has been heavy relative to yields obtained. The PNST test is not accurate in measuring recently applied N. For that reason, samples should be taken prior to N application. Because the test only measures nitrate-n present at the time the sample is taken, it should be taken prior to planting the crop, but not so far in advance that weeds would utilize part of the nitrate-n. With high N fertilizer prices, the PSNT test may pay big dividends. Producers should consult with their local Extension office or lab on proper sampling and handling procedures. -- Dave Whitney, Soil fertility specialist These e-updates are a regular weekly item from K-State Extension Agronomy. All of the Research and Extension faculty in Agronomy will be involved as sources from time to time. If you have any questions or suggestions for topics you'd like to have us address in this weekly update, contact Jim Shroyer, Research and Extension Crop Production Specialist and State Extension Agronomy Leader jshroyer@ksu.edu 5