North Dakota State University
NDSU Extension Service
No. 201, April 2003
http://www.ext.nodak.edu/extnews/snouts
Welcome to the Beginning of a New Growing Season
Nitrogen Management in Potatoes -- If We Only Knew . . .
Winter Injury/Kill in Alfalfa
Take Care When Starting Your Irrigation System
As we enter the 31st year for this irrigation newsletter, we are beginning to see a change in the climate of this region. Over the past 10 years, many people in different areas of North Dakota have had to live with excess water and periodic flooding. No area of the state has been excluded. However, that began to change last season as the southern third of North Dakota experienced a severe drought. At the same time, the northeast part of the state was still dealing with too much rain. Below normal precipitation last fall and almost no snow this winter have left many areas with inadequate soil moisture. If drought conditions persist, irrigation water management is going to be vitally important. Not only will individual irrigators need to pay more attention to water management, but access to water in entire aquifer systems could be affected.
The NDSU Irrigation Task Force, which I chair, selects the topics for articles in Water Spouts. We try to select topics to help better manage your irrigation systems and water resources. This year, we will watch for drought conditions and keep you updated on methods to help you do a good job of irrigating. The task force is comprised of the following individuals:
Tom Scherer, Extension Agricultural Engineer
Aung Hla, Extension Area Irrigation Specialist
Duane Berglund, Extension Agronomist
Dwain Meyer, Professor, Forage Management
Bob Henson, Assistant Agronomist, Carrington Research Extension Center
Blaine Schatz, Director, Carrington Research Extension Center
Paul Hendrickson, Research Specialist - Irrigation, Carrington Research Extension Center
Harlene Hatterman-Valenti, Assistant Professor, Plant Sciences
Gary Secor, Professor, Plant Pathology
Richard Greenland, Supervisor, Oakes Irrigation Research Site
Dean Steele, Associate Professor, Agricultural and Biosystems Engineering
Dave Kirkpatrick, Research Specialist, Agricultural and Biosystems Engineering
Dwight Aakre, Extension Agricultural Economist
Dave Franzen, Extension Soils Specialist
Bruce Seelig, Extension Water Quality Specialist
Kevin Sedivec, Extension Rangeland Management Specialist
Rudy Radke, Extension Area Agriculture Diversification Specialist
Frank Casey, Assistant Professor, Soil Science Department
Chet Hill, Extension Area Value-Added Specialist, Williston Research Extension Center
Jim Staricka, Soil Scientist, Williston Research Extension Center
Larry Cihacek, Associate Professor, Soil Science Department
Craig Kleven, Extension Agent, Kidder County
At the end of each Water Spouts article, the author's name, telephone number and e-mail address (if the author has one) are listed. If you have any questions about any article, please contact the author by whatever means is convenient. If you prefer, contact me for help. If you want to look at past issues of Water Spouts, they are available on the Internet at the address shown at the top of this newsletter (under the pumps).
Tom Scherer, (701) 231-7239
Extension Agricultural Engineer
tscherer@ndsuext.nodak.edu
Planting time is just around the corner, especially when it comes to potatoes. Some extremely mild days along with the lack of snow cover has many farmers thinking this spring will be early. As growers consider the various inputs needed for a successful potato crop, nitrogen rate and application timing probably enter into everyone's mind. How much should I apply? Should I split that into two, three or more applications? What are the consequences of applying too much or too little nitrogen? The list of questions could go on and on, and the answers to each question would vary with each grower, but there are some general recommendations that everyone should follow. First of all, consider your yield goal. Table 1 was developed by Dr. Carl Rosen, a soil fertility specialist at the University of Minnesota for potatoes grown on irrigated mineral soils.
Table 1. Nitrogen recommendation for irrigated potatoes
on mineral soils.
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Previous Crop
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Corn, small grains, Alfalfa, clover,
Yield goal sugarbeets, potatoes Soybeans black fallow
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(cwt/A) - - - - - - - - - N to apply (lb/A) - - - - - - - -
Less than 200 75 50 50
201 - 300 100 80 50
301 - 400 150 130 90
401 - 500 200 180 140
500 + 250 230 190
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As you can see, this table takes into consideration
the previous crop and the nitrogen credit from this crop.
The generalization that all cultivars grown on irrigated land in
North Dakota respond similarly to nitrogen may be a bit
simplistic; however, with the general short growing season and
the inconsistent weather during bulking, the nitrogen
requirements for a late maturing and an earlier maturing processing
potato (i.e. Russet Burbank and Shepody) may be comparable
or differ by less than 30 lb. N/acre. Dr. Jim Lorenzen and
others conducted a series of nitrogen trials from 1993 through 1997
on four cultivars (Goldrush, Shepody, Ranger Russet and
Russet Burbank) that varied in vine maturity from medium-early
to medium late/late. They used four nitrogen rates (75, 150,
225 and 300 lb. per acre) and split this into at least three
application timings. Results indicated that even though the earlier
maturing cultivars were more responsive to nitrogen (Table 2),
the highest total yield and greatest percentage of 6- to 16-oz.
tubers was between 150 to 225 lb. N/acre. Only once did the
highest overall total yield occur with the highest nitrogen rate,
which was the 300 lb. N/acre treatment (Table 3). In fact, the
highest yields for Ranger Russet and Russet Burbank were at 150
lb. N/acre three out of five years with rates above 150 lb.
N/acre causing reduced yields (Table 2). Specific gravity
generally decreased as the nitrogen rate increased (Table 3) and
average fry color was darker with the higher nitrogen
rates especially with Goldrush and Shepody (data not shown).
Table 2. Cultivar response to nitrogen from 1993 through 1997 at Oakes, N.D.
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Total Yield 6 oz. or Greater Tubers Specific Gravity
------------------------ ------------------------- -----------------------------------
93 94 95 96 97 93 94 95 96 97 93 94 95 96 97
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- - - - cwt/A - - - - - - - - - - - % - - - - - -
75 lb. N/A
Goldrush 246 401 332 171 210 72 60 64 62 69 1.088 1.082 1.076 1.077 1.074
R. Russet 273 367 307 118 177 72 64 77 56 68 1.101 1.097 1.086 1.081 1.089
R. Burbank 273 402 291 150 251 58 41 60 50 56 1.095 1.087 1.077 1.077 1.080
Shepody 265 321 292 157 161 80 63 84 73 73 1.090 1.087 1.076 1.083 1.079
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150 lb. N/A
Goldrush 328 428 305 223 288 75 75 72 78 73 1.081 1.079 1.069 1.076 1.076
R. Russet 328 440 313 163 259 74 71 75 72 70 1.098 1.093 1.084 1.079 1.089
R. Burbank 323 432 235 264 346 63 48 52 53 68 1.092 1.086 1.070 1.080 1.083
Shepody 322 387 340 267 316 76 77 77 78 85 1.088 1.084 1.075 1.081 1.084
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225 lb. N/A
Goldrush 326 490 319 342 325 82 77 76 79 71 1.078 1.077 1.067 1.075 1.070
R. Russet 334 407 302 176 249 74 66 76 57 76 1.094 1.089 1.085 1.081 1.089
R. Burbank 346 404 231 283 305 68 58 56 60 71 1.089 1.085 1.068 1.079 1.081
Shepody 380 483 258 307 334 86 87 77 82 87 1.080 1.083 1.069 1.078 1.081
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300 lb. N/A
Goldrush 327 467 252 276 301 72 85 73 77 63 1.073 1.074 1.066 1.071 1.066
R. Russet 293 428 248 191 264 75 57 68 67 74 1.095 1.088 1.081 1.081 1.087
R. Burbank 317 385 133 260 295 76 58 41 53 65 1.089 1.082 1.067 1.080 1.079
Shepody 342 528 253 361 321 89 85 82 82 83 1.080 1.078 1.070 1.085 1.080
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Table 3. Nitrogen effect on potato yield and dry matter content from 1993 through 1997 at Oakes, N.D.
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Total Yield 6 oz. or Greater Tubers Specific Gravity
------------------------ ------------------------- -----------------------------------
93 94 95 96 97 93 94 95 96 97 93 94 95 96 97
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- - - - cwt/A - - - - - - - - - - - % - - - - - -
75 lb. N/A 267 372 306 149 200 70 58 71 60 67 1.094 1.088 1.079 1.079 1.080
150 lb. N/A 326 422 299 229 302 74 65 69 67 75 1.089 1.085 1.074 1.079 1.083
225 lb. N/A 343 446 277 277 303 78 66 71 70 76 1.085 1.083 1.072 1.078 1.080
300 lb. N/A 320 452 222 253 295 70 66 66 69 71 1.084 1.080 1.071 1.079 1.078
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Goldrush 308 446 302 253 281 78 66 71 74 70 1.080 1.078 1.069 1.074 1.071
R. Russet 303 410 292 162 237 73 69 74 60 73 1.097 1.092 1.084 1.080 1.089
R. Burbank 322 406 223 239 299 67 46 52 54 65 1.091 1.085 1.071 1.079 1.081
Shepody 322 430 286 273 283 75 75 80 79 83 1.084 1.083 1.072 1.082 1.081
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Knowing how much nitrogen we're going to apply, we
now need to address application timing. Nitrogen applied early in
the season can easily leach beyond the potato root zone with
heavy rainfall or excess irrigation and may increase the potential
to increase groundwater contamination. Too much nitrogen
before or at tuberization can delay tuber initiation,
reduce yields, increase sugar-ends and decrease specific
gravity. However, the nitrogen supply early in the season must also
be adequate for vegetative growth. Research at Wisconsin
(Kelling and Speth, 1998) looked at the timing of nitrogen application
on irrigated potatoes from 1991 through 1996.
Researchers applied a total of 120 lb. N/acre in 1991-1993 or 100 lb.
N/acre in 1994-1996 in an attempt to not overshadow timing
response with extra nitrogen. Each year, a blanket 30 lb. N/acre
was applied at planting followed by either:
The results indicated that during a low leaching year (1991 and 1995), a split application was not better than a single application (Table 4). Delaying the nitrogen application past emergence tended to improve size but also hurt quality (data not shown). During leaching years, (1992, 1993, 1994 and 1996) splitting was better. However, in 1992 and 1994 applications after hilling resulted in somewhat lower yield and size. This was attributed to the heavy rain events in early July compared to leaching events in late July and August during 1993 and 1996. Researchers summarized by suggesting that approximately one-third of the supplemental nitrogen (50-70 lb. N/acre) should be applied by emergence and that the remainder (100 to 140 lb. N/acre for Russet Burbank) be applied at early to mid-tuberization. Reserachers recommended continued petiole nitrate-N monitoring and that if leaching occurs prior to 65 days after emergence, apply an additional 30-50 lb. N/acre.
Other researchers have also looked at nitrogen management for potatoes under irrigation. Results have shown that excessive applications during tuber initiation can cause excessive vine growth and delay tuber growth up to 10 days. Excessive nitrogen during tuber bulking can promote late season vegetative growth and delay maturity (Ojala et al., 1990). In Minnesota, Dr. Rosen showed that nitrogen uptake significantly preceded dry matter accumulation (Rosen, 1994). Total N uptake reached near maximum level approximately 70 days after emergence even though less than 60 percent tuber growth had occurred. Unfortunately, no research has been published on the effect of periodically applying small amounts of nitrogen after hilling through irrigation (spoon feeding).
Preliminary research at NDSU during 2001 examined two cultivars (Shepody, Russet Burbank), five nitrogen rates (0, 60, 120, 180, 240 lb. N/acre) and three application timings (33 percent at planting, hilling and hilling+21 days; 16.7 percent at planting, hilling and four, 14-day intervals till the end of July; and 16.7 percent at planting, hilling, hilling+14 days and six, 8.3 percent applications at approximately 10 day intervals until the third week in August). Results indicated that with Russet Burbank there was an increase in the total and number one yield with spoon-fed treatments (Table 5). The highest nitrogen rate (240 lb./acre) caused a yield decrease and specific gravity decreased as the nitrogen rate increased. With Shepody, the highest total and number one yield was with 120 lb. N/acre (Table 5). Nitrogen application timing had no effect on yield or specific gravity. Nitrogen rates above 120 lb./acre caused a yield decrease and specific gravity decreased as the nitrogen rate increased. Therefore, there may be benefit to the spoon-feeding approach for nitrogen management with Russet Burbank.
Table 4. Effect of N timing on Russet Burbank yield and
quality at Hancock, WI, 1991-1996.
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N treatments 1991 1992 1993 1994 1995 1996
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- - - - Total Yield (cwt/A) - - - -
Emergence (E) 495 345 319 380 403 331
Tuberization (T) 550 311 343 367 412 341
T+10 516 270 299 358 226 402
50% E and T 514 351 342 401 438 313
33% E, T, T+10 526 312 338 359 432 356
33% E, T+10, T+30 536 319 328 358 392 341
20% E, T, T+10, T+20, T+30 555 323 372 338 403 336
33% E, 66% T 543 371 335 391 400 360
33% E, 66% T+10 528 325 308 330 455 411
50% T, T+10 --- 308 346 351 437 371
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- - - - - - Grade A (%) - - - - - -
Emergence (E) 79 54 60 83 61 63
Tuberization (T) 72 59 65 79 47 70
T+10 76 62 58 80 40 70
50% E and T 75 60 61 79 55 59
33% E, T, T+10 80 51 63 79 5 73
33% E, T+10, T+30 76 55 62 78 57 65
20% E, T, T+10, T+20 T+30 77 56 64 78 56 66
33% E, 66% T 78 62 58 77 55 67
33% E, 66% T+10 77 59 55 78 58 74
50% T, T+10 --- 63 66 80 53 71
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- - - US #1, 6-13 oz (cwt/A) - - -
Emergence (E) 218 55 14 81 111 21
Tuberization (T) 220 82 24 70 87 41
T+10 186 77 9 99 85 50
50% E and T 176 74 20 76 107 25
33% E, T, T+10 208 37 9 69 110 32
33% E, T+10, T+30 215 50 18 54 91 17
20% E, T, T+10, T+20 T+30 223 54 19 72 110 21
33% E, 66% T 202 84 12 81 84 29
33% E, 66% T+10 198 60 10 48 106 48
50% T, T+10 --- 89 27 80 105 48
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Table 5. Effect of N rate and timing on potato yield and
quality at Dawson, N.D., 2001.
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Application Timings
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N Rate (lb/A) No splits 3 splits 6 splits 9 splits
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R. Burbank - - - - - - Total Yield (cwt/A) - - - - - -
0 346
90 350 338 399
120 361 349 393
180 337 394 389
240 314 310 369
Shepody
0 269
90 354 335 375
120 396 378 382
180 325 372 307
240 297 311 293
R. Burbank - - - - - - - - US #1 (cwt/A) - - - - - - -
0 309
90 319 313 364
120 314 319 359
180 299 361 351
240 282 282 331
Shepody
0 255
90 343 320 356
120 361 362 359
180 300 345 287
240 250 257 259
R. Burbank - - - - - - - Specific Gravity - - - - - -
0 1.082
90 1.082 1.077 1.082
120 1.083 1.082 1.079
180 1.078 1.081 1.076
240 1.075 1.074 1.079
Shepody
0 1.083
90 1.083 1.079 1.084
120 1.074 1.082 1.077
180 1.081 1.077 1.076
240 1.07 1.066 1.079
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In summary, nitrogen management is extremely difficult
due to the mobility of the compound and Mother Nature. If we
knew what weather conditions (air temperature and rainfall) we
were going to face this season, we would know how much
nitrogen to apply and when to make those applications. The problem
is that we can't predict such factors. Therefore, we need to
make environmentally conscious decisions when it comes to
nitrogen management. We need to give proper nitrogen credit for
the previous crop. We need to apply reasonable amounts
of supplemental nitrogen which research has shown to be
around 180 lb./acre when there is approximately 40 lb./acre
residual nitrogen. We need to make split applications given the
possibility of leaching rain events and we need to monitor
nitrogen uptake by the plants, making sure that we don't apply
nitrogen too late in the season when plant uptake and use in
tuber bulking is unlikely.
Harlene Hatterman-Valenti (701) 231-8536
Assistant Professor, High Value Crops Research
h.hatterman-valenti@ndsu.nodak.edu
The 2002-2003 winter will go down in the record books as relatively mild with a cold latter part in February and March. One might think that perennials like alfalfa should have little problem surviving the winter. However, I am very concerned that North Dakota may experience significant winter injury or winter kill in alfalfa as a result of less-than-average snowfall. Actually, total snowfall isn't as important as the distribution of snow relative to outbreaks of sub-zero temperatures. Very cold temperatures with a lack of snow cover cause the soil temperature to decrease markedly compared to snow-covered areas.
Alfalfa crowns can survive two-inch soil temperatures in the range of 12 to 15o F, very similar to the killing temperature of winter wheat except the crown is much shallower in wheat than alfalfa. Dr. John Enz, the NDSU climatologist, reports that NDAWN had 12 sites in North Dakota that recorded soil temperatures at the two-inch depth. Remember that these sites are under turf grass cover and would be warmer than an alfalfa field.
Searching the records, eight sites were found with two-inch soil temperatures less than 15o F this past winter. The Langdon area has the most concern with three, 60-plus hour periods with soil temperature less than 15o F and a minimum soil temperature of 7o F. Minot and Williston are the other areas of concern with soil temperatures below 15o F for 60-plus hours and minimum soil temperatures in the 8 to 10o F range. These areas will likely experience winterkill on older stands and winter injury on new stands. The Fargo area may also have some winter injury or kill, with several incidences of soil temperature less than 15o F, but the duration has been much less. Areas near Grand Forks, Harvey and Dickinson have had no temperatures less than 15o F, while Carrington, Streeter, Bottineau and Hettinger have had one or two dates with less than 15o F for short time periods.
Sites that have been exposed to less than 15o F soil temperatures for short durations will likely show marked effects of management on winter kill or winter injury. Producers in these areas that have old stands, took a fall harvest, are under four-cut management, have nutrient deficiency(s), have less persistent varieties or a combination of these will experience more winter kill or injury than producers that have new stands, took no fall harvest, are under three-cut management, have good soil fertility or have persistent varieties.
Producers located in the Langdon, Minot and Williston areas should dig plants from a few representative areas as soon as the frost goes out of the soil. Split the roots. If the root is soft, yellowish in color and somewhat stringy in nature, the plant is most likely dead and the stand should be terminated. If the root is firm and white, the plant is probably alive. If the center of the root is black, but the outside is white, the plant has Fusarium root rot probably caused by a previous year's winter injury. If the root has no black in the interior, is somewhat yellow on the interior and the outside is white and firm, the plant has had serious winter injury but may survive.
The best method to determine if a winter-injured stand is still productive is to count the number of stems per square foot. If you have 50 plus stems per square foot, the stand will be fully productive. If you have 30 to 40 stems per square foot, the first-harvest yield will be less than normal but I would delay the first harvest until 25 percent bloom on uninjured plants and wait to see how many stems occur in the next harvest. Alfalfa has the ability to repair some winter injury and regain some of its productivity. If you have less than 20 new stems per square foot, consider terminating the stand and seeding a new one.
Unfortunately, winter injury and/or winterkill will be a factor this year in many alfalfa fields. Keep a close eye on your fields this spring so a decision can be made early whether to rotate to another crop if necessary. One should not attempt to thicken up the stand by over seeding following winter kill or reseeding the stand on the same field without an intervening crop since autotoxicity could be a major problem.
Dwain W. Meyer (701) 231-8154
NDSU Extension Specialist, Forages
Dwain.meyer@ndsu.nodak.edu
If we have a dry spring, many irrigation systems are going to be started earlier than normal. If you have electric powered irrigation pumps and/or systems, please be careful when starting them the first time.
The most common problem is rodents getting into electric control boxes during the winter and causing damage. The damage may result from rodents chewing on wires and control switches or corrosion caused by urine. If you don't look for this type of damage before turning on the system, some components could explode. You could be hurt if standing in front of the electric control box.
As a precaution, before turning on any electric equipment, open all electric control panels (this includes pivot control panels and tower boxes) and look for any evidence of rodent damage. Also, check electric motors and phase converters. If there is damage, look for the point of entry and plug it. I have seen several electric control boxes with mouse nests in them, and the point of entry was through the conduit from the motor. The screens on the electric motor had been removed and the mice entered the motor and followed the conduit into the control box. From the mouse's point of view, this was a perfect nesting situation.
Filling pipelines can be another major problem when irrigation pumps are turned on for the first time in the spring. Pipelines, especially those that go through low areas and swamps, should be filled very slowly. This means setting the valve at the pump site so it is about one-quarter open. Filling the pipeline slowly allows air to escape easily and prevents damage due to water hammer. It is not uncommon for irrigation dealers to be called in the spring to repair a ruptured pipeline because it was filled too fast and residual ice left in the pipe caused a blockage.
Spring is always a busy time of the year, and sometimes it is easy to forget about getting the irrigation system ready. Here is a checklist to help get your irrigation system up and running smoothly:
Tom Scherer (701) 231-7239
NDSU Extension Agricultural Engineer
tscherer@ndsuext.nodak.edu
Water Spouts, No. 201, April 2003
NDSU Extension Service, North Dakota State University of Agriculture and Applied Science, and U.S. Department of Agriculture cooperating. Sharon D. Anderson, Director, Fargo, North Dakota. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. We offer our programs and facilities to all persons regardless of race, color, national origin, religion, sex, disability, age, Vietnam era veterans status, or sexual orientation; and are an equal opportunity employer. This publication will be made available in alternative formats for people with disabilities upon request, 701/231-7881.
North Dakota State University
NDSU Extension Service