Number 354 June 15, 2012

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1 Number 354 June 15, Drought Severity Classification: What indicators are used? 1 2. Factors to consider before burning or baling wheat residue 3 3. Common bunt (stinking smut) on wheat 4 4. K-State and KARA partner for Field Day July Comparative Vegetation Condition Report: May 29 June Drought Severity Classification: What indicators are used? Drought is once again a major focus for many Kansans this summer, despite the rains some areas received this week. One means of measuring the drought is the Drought Severity Classification. Below is the list of indicators and their ranges from the National Drought Mitigation Center: Short-term drought indicator blends focus on 1-3 month precipitation. Long-term blends focus on 6-60 months. Additional indices used, mainly during the growing season, include the USDA/NASS Topsoil Moisture, Keetch-Byram Drought Index (KBDI), and NOAA/NESDIS satellite Vegetation Health Indices. Indices used primarily during the snow season and in the West include snow water content, river basin precipitation, and the Surface Water Supply Index (SWSI). Other indicators include groundwater levels, reservoir storage, and pasture/range conditions. 1

2 Drought Blends as of 9-June-2012 Current Kansas Drought Monitor: -- Mary Knapp, State Climatologist 2

3 2. Factors to consider before burning or baling wheat residue Many producers may be planning to burn their wheat stubble this summer to help control volunteer plants, weeds, and certain diseases. Others may be planning to bale and ammoniate the residue for badly needed feed. While burning is inexpensive and baling serves a valuable function for livestock, producers should understand the true value of residue ahead of time. Some of the information below comes from K-State Extension publication MF-2604, The Value of Crop Residue. There are four main factors to consider. Loss of nutrients Wheat stubble contains valuable nutrients that can be recycled in the soil for future crop use. Baling and removing the straw obviously removes a large percentage of these nutrients. The issue with burning is a little more complex. The products of burned wheat stubble are gases and ash. Nutrients such as nitrogen (N) and sulfur (S) are largely combustion products, while phosphorus (P) and potassium (K) remain in the ash. When residue is burned, about a third of the N and S will volatilize. The nutrients in the ash may remain for use by the plants, if it doesn t blow away first. Therefore, instead of cycling these important plant nutrients back into the soil, they can essentially become air pollutants when the residue is burned. Amounts of nutrients remaining in wheat stubble (assuming 50 bu/ac yield) Nutrient Pounds present in 5,000 lbs of wheat straw N 27.0 P 2 O K 2 O 37.5 S 5.0 Protection from soil erosion Bare soil is subject to wind and water erosion. Without residue, the soil will receive the full impact of raindrops, thus increasing the amount of soil particles that may become detached during a rainfall event. Bare, tilled soils can lose up to 30 tons per acre topsoil annually. In no-till or Conservation Reserve Program (CRP) systems where residue is left, annual soil losses are often less than 1 ton per acre. The detachment of soil particles can lead to crusting of the soil surface, which then contributes to greater amounts of sediment-laden runoff, and thus, reduced water infiltration and hotter, drier soils. Leaving residue on the field also increases surface roughness, which decreases the risk of both wind and water erosion. Most agricultural soils in Kansas have a T value, or tolerable amount of soil loss, of between 4 and 5 tons per acre per year, which is about equal to the thickness of a dime. To prevent water erosion, 30% ground cover or greater may be needed to reduce water erosion to T or less, especially in fields without erosion-control structures such as terraces. Standing stubble is more effective at preventing wind erosion than flat stubble. 3

4 Moisture infiltration rates and conservation Wheat residue enhances soil moisture by increasing rainfall infiltration into the soil. Residues physically protect the soil surface and keep it receptive to water movement into and through the soil surface. Without physical protection, water and soil will run off the surface more quickly. Ponded infiltration rates were measured at Hesston in September Very low infiltration rates (1.9 mm/hr) were observed for continuous winter wheat in which the residue was burned each year prior to disking and planting the following crop. In contrast, high infiltration rates (13.3 mm/hr) were observed for a no-till wheat/grain sorghum rotation. Another way residue increases soil moisture is by reducing evaporation rates. Evaporation rates can decline dramatically when the soil is protected with residue. Residue blocks solar radiation from the sun and keeps the soil surface cooler. Soil quality concerns Over time, the continued burning or baling of cropland residue could significantly degrade soil organic matter levels. By continually burning or baling residue, soil organic matter is not allowed to rebuild. Soil organic matter is beneficial for plant growth as it contributes to water holding capacity and cation exchange capacity. Soil organic matter binds soil particles into aggregates, which increases porosity and soil structure and thus, increases water infiltration and decreases the potential for soil erosion. One burn or baling operation, however, will not significantly reduce the organic matter content of a soil. If producers do choose to burn their wheat stubble, timing is important. It s best to burn as late as possible, close to the time when the next crop is planted. This minimizes the time that the field will be without residue cover and vulnerable to erosion. Before choosing to burn residue, producers should check with the USDA Natural Resources Conservation Service and/or the Farm Service Agency to find out if this will affect their compliance in any conservation programs. The timing of baling is not as critical since this practice does not remove all the residue down to the ground, or leave the field entirely unprotected. -- DeAnn Presley, Environmental Soil Science and Soil and Water Management Specialist deann@ksu.edu -- Jim Shroyer, Extension Agronomy State Leader jshroyer@ksu.edu 3. Common bunt (stinking smut) on wheat Common bunt (stinking smut) occurs somewhere in Kansas almost every year, resulting in significant price penalties or rejected loads of grain. This fungal disease causes deformation of wheat kernels, and infected kernels often have a gray color. The infected kernels are filled with black powdery spores as opposed to the normal white starches of healthy kernels. The fungus produces 4

5 volatile chemicals that have a strong fishy odor. This odor is readily detected in loads of grain and may persist through the milling and baking process. Symptoms of common bunt (stinking smut) in wheat grain (right), compared to healthy wheat kernels (left), Photo by Erick DeWolf, K-State Research and Extension. Common bunt is a seed-borne disease. The disease persists between seasons on seed that was contaminated with the fungus during harvest or subsequent grain handling. The spores will survive on the outside of the kernels until fall, when they germinate and infect the developing seedlings shortly after planting. This infection process is favored by cool and wet fall conditions. Survival in the soil is considered rare in Kansas, because summer rainfall is normally sufficient to trigger germination of the fungal spores left in the field after harvest. The potential for survival in the soil is greater when soil conditions remain dry. Unfortunately, there do not appear to be many options for using the rejected grain. Saving this grain for seed will increase the chances of having problems with bunt in following years. In some situations, I have heard of growers working with local feed lots to move rejected grain. The availability of this option will likely vary regionally within the state. Management options for common bunt: Fungicide seed treatments: Seed treatment fungicides are the first line of defense against seed-borne fungal diseases like common bunt. Even low levels of bunt can become a serious problem the following year and growers that have detected bunt or smut should use fungicide seed treatment for all their wheat. Products such as Dividend Extreme, Raxil MD, and Charter are all highly effective at controlling seed-borne diseases like common bunt and loose smut. Thorough coverage of the seed with the fungicide is very important and growers should consider having their seed commercially treated were possible. When used properly these seed treatments are able to protect more than 98% of the kernels from infection. Even at this high level of control, it may take several years of persistent use of the seed treatment fungicide to completely eliminate the disease. Disease free seed: Common bunt is most likely to be a problem when wheat has been saved for seed for 2 or more years. Renewing the seed supply with certified seed every few years will greatly reduce the risk of future common bunt problems. On farms with a history of bunt problems, it is a 5

6 good idea to have the new seed treated with a fungicide seed treatment. This seed treatment will reduce the risk of contamination from equipment (trucks, augers, grain charts used to move and handle the new seed) and eliminate the risk of infection from soil-borne sources of the fungus. Crop rotation and volunteer wheat: It is also important to clean up volunteer wheat in fields with a history of common bunt. Any grain that passed through the combine during harvest is likely contaminated with the spores of the bunt fungus. If weather conditions are right, these volunteer plants could become infected with common bunt and negate the efforts to use clean seed or fungicide seed treatments. Because the infection is favored by cool and wet conditions, the late flushes of volunteer wheat are most at risk for infection. Therefore, crop rotation in fields with a history of bunt is probably the best option. Where rotation is not possible it is important to remain vigilant about volunteer control prior to planting the next wheat crop. Wheat varieties with the Clearfield technology that allows use of the herbicide Beyond to control volunteer wheat and feral rye may also be an option for some growers. Common bunt can be a frustrating problem, but the disease can be controlled with a few adjustments to the production practices. Remain persistent and pay attention to details so that you receive maximum benefit for your efforts. -- Erick DeWolf, Extension Plant Pathology dewolf1@ksu.edu 4. K-State and KARA partner for Field Day July This summer K-State Research and Extension and the Kansas Agribusiness Retailers Association (KARA) will partner to host an annual agronomic educational field day on July at the K-State North Agronomy Farm and facilities. This is an annual program that consistently provides relevant and current information. Highlights for this year s program include: insects and diseases, corn and sorghum growth and development in response to management and the environment, herbicide efficacy and mode of action, starter fertilizers, foliar feeding, and plant analysis Agricultural retailers across the state are encouraged to attend and bring an interested producer with them. For registration information please go to: or call (785) Comparative Vegetation Condition Report: May 29 June 11 K-State s Ecology and Agriculture Spatial Analysis Laboratory (EASAL) produces weekly Vegetation Condition Report maps. These maps can be a valuable tool for making crop selection and marketing decisions. Two short videos of Dr. Kevin Price explaining the development of these maps can be viewed on YouTube at: 6

7 The objective of these reports is to provide users with a means of assessing the relative condition of crops and grassland. The maps can be used to assess current plant growth rates, as well as comparisons to the previous year and relative to the 21-year average. The report is used by individual farmers and ranchers, the commodities market, and political leaders for assessing factors such as production potential and drought impact across their state. The maps below show the current vegetation conditions in Kansas, the Corn Belt, and the continental U.S, with comments from Mary Knapp, state climatologist: Map 1. The Vegetation Condition Report for Kansas for May 29 June 11 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows highest NDVI values are in the eastern third of the state. There is a splice line in the western third due to persistent cloud cover during this two-week composite period. Unfortunately, that cloud cover did not translate to widespread precipitation. Warm temperatures and low rainfall are hindering plant development. 7

8 Map 2. Compared to the previous year at this time for Kansas, the current Vegetation Condition Report for May 29 June 11 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows that while parts of western Kansas have higher biomass production, most of the state has lower NDVI readings. Plant maturity is running 3 weeks ahead of normal. At the beginning of the week, 53 percent of the wheat was reported harvested. 8

9 Map 3. Compared to the 23-year average at this time for Kansas, this year s Vegetation Condition Report for May 29 June 11 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows that vegetative conditions are below normal for all except the eastern third of the state. A splice line is visible in western Kansas due to persistent cloud cover in some areas during this two-week composite period, but that cloud cover did not result in significant moisture. Only extreme northeast Kansas had rainfall amounts over an inch. 9

10 Map 4. The Vegetation Condition Report for the Corn Belt for May 29 June 11 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows that drought stress is becoming visible in western Kansas and Nebraska, as well as parts of Indiana and Ohio. In most of southern Missouri, the reported dryness is just becoming visible. The exception is in the Bootheel Region, which was impacted earlier by low precipitation. 10

11 Map 5. The comparison to last year in the Corn Belt for the period May 29 June 11 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows that the central and northern areas of the region have higher photosynthetic activity, as does parts of western Kansas. In Western Kansas, this is due mainly to the very poor conditions last year at this time. In contrast, western South Dakota, western Nebraska, and central Kansas have much less photosynthetic activity this year than during this same two-week period last year. Wheat has matured early, and pastures are showing increased stress due to the dry conditions. 11

12 Map 6. Compared to the 23-year average at this time for the Corn Belt, this year s Vegetation Condition Report for May 29 June 11 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows higher NDVI values in northwestern Iowa, eastern Nebraska, and central Illinois. These areas have seen more favorable moisture than average. In western Kansas, early plant development and low rainfall has reduced photosynthetic activity. Some producers have delayed planting summer row crops due to lack of moisture. 12

13 Map 7. The Vegetation Condition Report for the U.S. for May 29 June 11 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows that the eastern half of the country generally has average or above-average levels of biomass production. Exceptions can be seen in eastern Indiana and western Ohio, where dry conditions are beginning to be felt. Impact of the dryness can also be seen in the High Plains east of the Rockies, particularly in eastern Colorado, eastern Wyoming, and western Nebraska. 13

14 Map 8. The U.S. comparison to last year at this time for the period May 29 June 11 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows that shows the Central Plains and the central Rockies have the biggest decrease in photosynthetic activity. In contrast, the Central Rockies into the Pacific Northwest have much higher NDVI values. A good part of this increase is due to the rapid snowmelt this year, as compared to last. Vegetation conditions are expected to worsen as summer progresses. 14

15 Map 9. The U.S. comparison to the 23-year average for the period May 29 June 11 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows that the Central Plains has much below-average photosynthetic activity. The low NDVI values in the Pacific Northwest are due primarily to cloud cover. Above-average NDVI values in western Wyoming and western Colorado are due to low snow pack, not necessarily healthy vegetation. Northwestern Colorado currently is in the Extreme drought category. Note to readers: The maps above represent a subset of the maps available from the EASAL group. If you d like digital copies of the entire map series please contact us at kpprice@ksu.edu and we can place you on our list to receive the entire dataset each week as they are produced. The maps are normally first available on Wednesday of each week, unless there is a delay in the posting of the data by EROS Data Center where we obtain the raw data used to make the maps. These maps are provided for free as a service of the Department of Agronomy and K-State Research and Extension. -- Mary Knapp, State Climatologist mknapp@ksu.edu -- Kevin Price, Agronomy and Geography, Remote Sensing, Natural Resources, GIS kpprice@ksu.edu -- Nan An, Graduate Research Assistant, Ecology & Agriculture Spatial Analysis Laboratory (EASAL) nanan@ksu.edu 15 These e-updates are a regular weekly item from K-State Extension Agronomy and Steve Watson, Agronomy e-update Editor. 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 Steve Watson, swatson@ksu.edu, or Jim Shroyer, Research and Extension Crop Production Specialist and State Extension Agronomy Leader jshroyer@ksu.edu