No. 163, August 1997
http://www.ext.nodak.edu/extnews/snouts
1997 Experiment Station Field Days
Dry Bean Production Guide Available
Jim Weigel to Leave NDSU Extension Service
CRP to Irrigated Crops
Plants for Salt-Affected Soils
Tech Tip: Scratch and sniff (heel and toe) just won't do!
Tech Tip: Do you need pressure regulators?
Oakes . . . . August 19 (Field Crops—9 a.m.)
A new pocket-sized dry bean production guide is a now available. It contains a broad array of useful production information such as variety descriptions, estimations of yields, weed control, diseases, insect management, irrigation management, market grades, drying, storage and much more.
This publication was a cooperative effort between the Northarvest Bean Growers Association and NDSU Extension Service. Northarvest Bean Growers Association members will receive copies from the Association. Copies are also available from the Agriculture Communication Distribution Center, P.O. Box 5655, Fargo, ND 58105, (701) 231-7883, for $1.85 per copy plus $1.50 shipping and handling, or call for quantity rates.
Tom Scherer, (701) 231-7239
Extension Agricultural Engineer
tscherer@ndsuext.nodak.edu
This is the last article I will write for "Water Spouts" as an employee of NDSU Extension Service. I have accepted a position in Casper, Wyoming with the Bureau of Reclamation as a water conservation engineer. The primary focus of my work will be helping irrigation districts to develop and implement water conservation plans and practices.
After graduating from NDSU with a degree in agricultural engineering in 1984, I worked for the Garrison Diversion Conservancy District as an irrigation advisor in Oakes, N.D. I spent most of my time at the Oakes Irrigation Field Trials, doing research on irrigated crop management practices.
In 1987, I accepted my current position as area irrigation specialist in Carrington. My position is a result of a three way cooperative agreement between NDSU Extension Service, Garrison Diversion Conservancy District, and the Bureau of Reclamation. This new position opens up new opportunities and challenges for myself and my family.
I have enjoyed working with NDSU, the farmers and citizens of North Dakota and with the Garrison Diversion Project. This has been a positive and rewarding experience for me. I will miss the many fine people I have had contact with over the past 13 years. They have enriched my life and I hope I have helped them utilize one of North Dakota's most precious resources.
Jim Weigel, (701) 652-3194
Area Specialist, Irrigation
One of the first decisions irrigation farmers will face when breaking out CRP lands is what crops should be produced and what tillage system should be used. Most lands contracted in the CRP program were removed from crop production because the fields were highly erodible and usually tended to be drought susceptible. The USDA-NRCS Conservation plans will largely determine what type of tillage and the amount of residue which needs to be left on the surface to protect the fragile soils.
The first step in any well planned CRP land break-out that is returned to crop production is to test for fertility levels and scout for pest and weed problems. Early planning will help in crop selection, pest management and providing adequate fertility for a growing crop.
In North Dakota, crops such as corn, soybeans, dry beans, potatoes, alfalfa, and field pea are all potential crops on CRP break-out lands intended for irrigation.
Which crops should be grown initially on CRP lands is a question facing many operators and owners. There is no definite answer for all situations. In many cases, each CRP field is site specific and must be managed as such. Many factors must be taken into account such as:
Use of legumes such as soybean, dry beans and field pea should also be considered when moisture is adequate and where they are climatically adapted. Soybean is less risky in the eastern third of North Dakota while field pea will do fairly well state-wide but perform best in the northern third of the state. Legumes planted with properly inoculated seed should provide benefits to most crops that follow in a rotation. CRP lands in most instances will be extremely low in N. (Soil tests have shown only 8-12 lbs/A of nitrogen available).
Grain legumes will fix their own N and also provide residual N requirements for sequential crops the following year. Recent research shows only one response for year after soybean, and most likely a similar response for field pea.
The design of irrigated rotations should consider the best crop choice; best cropping sequence for control of disease, weeds, and insects; soil temperature at planting time; seed zone moisture content; crop residue cover to protect fragile soils from erosion; varying rooting depths; labor and equipment use. As a field comes out of CRP grass into crop production, all rotation principles must be applied. A diversity of crop species over 3-4 year rotations with reduced tillage would be most ideal. Growing continuous corn with excessive tillage would result in a return within two years to soil conditions of ten years prior when the lands were seeded into CRP. All soil health gains would be lost. When CRP land has been in grass-sod for 10 years, special attention needs to be given to the cropping and fertilizer program that follows.
Consider longer rotations, crop diversity and flexibility in cropping CRP land. Information on vegetation management and weed control when breaking land out of CRP is somewhat limited. Few researched field sites for recommendations are available. Each CRP field also is somewhat site specific with a different mix of grass species, legumes and perennial weed problems. A similar situation for comparison is breaking-out established pasture into cropland.
For most situations, grazing or haying in late summer and/or fall burning will help remove excessive vegetation residues found in CRP lands. However, burning is not the recommended practice as most CRP lands are prone to erosion problems. Also, removal of valuable organic matter by burning would return the land to conditions of 10 years ago with little or no soil improvement.
Some CRP land will require some tillage to help decompose residues and for leveling purposes due to excessive roughness caused by certain small animals or bunch type grasses. Herbicide applications made several weeks prior to tillage will reduce vegetation and make tillage more efficient. Late summer or early fall herbicide treatments are vital with certain perennial grasses and perennial weeds. These control measures should be followed by a vigorous weed control program next spring if crops are to be planted and grown.
Spring plowing will be one option some producers may choose. Plant residues will decompose readily under this practice and land will be exposed to erosion. Certain perennial weeds, alfalfa and perennial grasses will not always be controlled by plowing. Growers who choose tillage alone without herbicides will find that preparing a suitable seed bed will be difficult and require numerous trips. Tillage alone tends to bring up sod clumps that are difficult to handle and make preparing a satisfactory seedbed a challenge. On highly erodible acres, it will be impossible to maintain sufficient residue to adequately protect the soil with the extensive tillage that will be required to prepare a seedbed with tillage alone.
The use of both non-selective and selective herbicides will be essential whether CRP land will be returned to crop production with or without tillage. In most instances late summer and fall herbicide applications will be more effective in control of vegetation and/or weeds than spring applications. Residual weed management also maybe required to control certain annual weeds in the crops which follow. In addition to herbicides, the use of mechanical and cultural weed management should be included in all crop production systems.
Duane R. Berglund,(701) 231-8135
NDSU Extension Agronomist
dberglun@ndsuext.nodak.edu
Salt-affected soils are those soils which have high levels of soluble salts and/or sodium in excess of limits which can be tolerated by crops. These soils with excess soluble salts are referred to as SALINE SOILS. Soils with excess sodium are referred to as ALKALI (SODIC) SOILS. Soils containing both high levels of soluble salts and sodium are called SALINE-ALKALI SOILS.
Perennial plants, especially some grasses, possess the highest tolerance to saline-alkali soil conditions. The tolerance level of a particular crop to saline or alkali soils is determine by its potential to produce a satisfactory yield. NOTE: if desirable native plants will not grow on saline or alkali soils, it is unlikely that seeded grass and legume crops will become established.
Soils with adequate internal drainage under natural conditions generally do not become salt-affected. In well-drained soils, soluble salts are transported by a downward movement of water in the soils. Soils may become salt-affected if there is an upward movement of water from a shallow water table, depositing salts in the upper soil profile with water evapotranspiration; from ground water seepage, depositing salts on the upper surface when water flows through the system and out at the seep; or from saline water overflow which evaporates leaving a salt deposit on the surface.
A soil test is the best way to determine the severity of the soluble salt and/or sodium problem in soils. The level of soluble salts in soil is expressed in terms of electrical conductivity (EC) - millimhos per centimeter (mmhos/cm). The influence of soil salinity on plant growth is greater on coarse-textured soils than on medium and fine-textured soils. Coarse-textured soils hold less moisture per foot of depth than medium- and fine-textured soils. Therefore, at the same soil salinity level, coarse-textured soils will have greater concentration of soluble salts in the water than heavier soil textures. The soil salinity class for soils based on textural groupings is provided in Table 1.
Table 1. Electrical conductivity (EC) of the soil and the influence of
soil texture on soil salinity class.
---------------------------------------------------------------------------------------
SOIL TEXTURE
-----------------------------------------------------------------------
EC Coarse Medium Fine
---------------------------------------------------------------------------------------
(mmhos/cm) - - - - - - - - - - - - - Soil salinity class - - - - - - - - - - - - -
0 - 1.0 non to slightly saline non-saline non-saline
1.0 - 2.0 moderately saline slightly saline slightly saline
2.0 - 4.0 strongly saline moderately saline slightly saline
4.0 - 7.0 very strong saline strongly saline moderately saline
Over 7.0 very strongly saline very strong saline strong saline
---------------------------------------------------------------------------------------
The ph level of a soil indicates whether the soil is acidic or basic. Soils with a ph level below 6.6 is considered acid, 6.6 to 7.3 near neutral and 7.4 and above is basic. Soils rated strongly basic will usually be difficult to revegetate because they often contain excess levels of sodium. These problem soils are often not economically feasible to correct. These sodic or alkali-affected soils create a surface crusting which slows water intake and restricts emergence of crop seedlings.
SALT-AFFECTED SOILS ARE BEST USED FOR HAY AND PASTURELAND. Forage production potential depends on the level of salts in the soil and the salt tolerance of grass and legume species selected. In general, perennial grasses are more tolerant to saline-alkali soils than legumes. Wheatgrass and wildrye grass species are the most saline tolerant plants and are recommended in permanent grass or grass/legume mixtures.
Tall wheatgrass tends to be the most tolerant to very strongly saline-alkali soils, followed by intermediate wheatgrass, western wheatgrass, slender wheatgrass, and beardless wildrye. Altai and Russian wildrye, and pubescent wheatgrass will also do well in strongly saline-alkali soils. Moderately saline soils can be planted to crested wheatgrass, creeping foxtail, as well as any of the grasses mentioned earlier. Alfalfa can be added to the seed mixture in slightly to moderately saline soils. If soils are only slightly saline, smooth bromegrass and reed canarygrass can be substituted into the grasses mixture.
Seeding should be conducted when soil moisture conditions are high. Fall plantings have resulted in better stands than spring planting. Seed at or near the time of freeze-up to assure no germination will occur until the following spring when moisture is highest. Saline-alkali soils are usually drier in the fall, permitting machinery to cross with less difficulty.
For more information on grass varieties to plant on saline-alkali soils, see NDSU Extension Service circular R-794: Grass Varieties for North Dakota.
Kevin Sedivec,(701) 231-7647
NDSU Extension Rangeland Specialist
ksedivec@ndsuext.nodak.edu
Soil moisture in the top few inches of soil evaporates quickly and does not adequately reveal soil moisture levels in the root zone. Do not rely on scraping the soil surface with the heel of your boot to determine when to irrigate. Use a soil moisture probe or dig a hole with a shovel to determine how far down the moisture is and how dry it is.
"Heel and toe" will cost you money by over irrigating or by not getting the soil moisture down into the root zone ahead of the roots. Roots will not grow into dry soil and cannot utilize nutrients located in dry soil. A hot dry spell will definitely hurt yield if you have not been monitoring soil moisture levels and maintaining adequate moisture. You have too much invested in equipment to do a poor job of managing the water. NDSU Extension Service personnel are available to assist you in setting up a water management program.
A properly designed sprinkler package should allow no more than a 10 percent variation in water application depth over a field. A variation in applied water depth greater than 10 percent indicates some parts of the field are over irrigated and some are under irrigated. Pressure regulators can reduce the water application variation. This could be very important for high value crops such as potatoes and carrots.
If you are currently irrigating, and are confident that your nozzles are not worn, place several large diameter rain gages (not the 1-inch ones) in small clusters at both the highest elevation and lowest elevation in the irrigated field near the outer towers (they cover the most acres). Irrigate over them and record the average depth collected at each location.
Evaluate how much of the field is affected by the elevation extremes. If the affected area is small, regulators may not be of great benefit to you. Repeat this test on different parts of the field to more thoroughly evaluate the need for regulators.
Uniform application is extremely important if you are injecting chemicals through the irrigation system.
If your sprinklers are worn this test may be of little benefit to you.
Jim Weigel,(701) 652-3194
NDSU Extension Area Irrigation Specialist
No. 163, August 1997
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