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Thursday, April 16, 2015

New bulletin helps growers manage the rotation from alfalfa to corn

Jeff Coulter, University of Minnesota

Crops that follow alfalfa usually benefit from reduced or eliminated nitrogen requirement from fertilizer or manure, increased yield potential compared to following other crops, and reduced pest pressure. A new Extension bulletin describes management practices for alfalfa termination and the two subsequent corn crops that will help growers utilize the benefits of alfalfa: http://z.umn.edu/rotation

Wednesday, April 15, 2015

How Deep Dare I Drill Wheat, Barley and Oats Down to Find Moisture?

Ideally we like you to seed wheat, barley, and oats at 1.5 to 2 inches of depth.  The idea is that the seed should be placed deep enough to have access to adequate moisture yet shallow enough to emerge as quickly as possible. Seeds too close to the surface absorb moisture but are at risk of dying because roots cannot reach moisture quickly enough to sustain the germination and seedling growth.  Deeper seeding can reduce stand density and plant vigor because the inability of the coleoptile to reach the surface. 

Given the extremely dry conditions the question arises how deep we dare to drill wheat, barley, and oats down to place the seed into moisture.  There are several factors to consider; including the crop itself, the variety in question, and the soil type into which the seed will be placed. On average, oats is the most tolerant to placing deeper than the optimum 1.5 to 2 inches, whilst barley is the least tolerant.

Varieties of each of the three species differ genetically in the maximum length of their sub-crown internode and their coleoptile.  The sub-crown internode moves the crown from the seed towards the surface and whether a sub-crown internode develops is a function of seeding depth.  Seeding deeper than 1.5 inches generally will result in the development of a sub-crown internode.  The maximum length of the sub-crown differs between cultivars and although not a lot of data is available you can assume that shorter statured varieties have shorter sub-crown internodes. Oats is different than either wheat or barley as the internode between the scutellum and coleoptile is also able to elongate, thereby allowing the oats to the most tolerant to seeding deep (up to approx.  4 inches)
The maximum coleoptiles lengths differ between varieties within each of the species.  The average plant height of varieties as reported in the variety trials correlates reasonably well with the length of the coleoptile and can be used guidance to assess the risk of planting too deep.  Table 1 summarizes the maximum coleoptile length measured in a growth chamber experiment using germination paper of a number of HRSW and barley cultivars.
Finally, finer textured soils create more resistance for emerging seedling than coarser textured soils, even in the absence of a crust.  Therefor you have less leeway to place the seed deeper and into moisture in finer textured soils.  The University of Nebraska suggests the difference being about a half inch.

Bottom line – barley should probably not be seeded much deeper than 2 inches, while many of the semi-dwarf wheat varieties probably should be seeded much deeper than 2.5 inches.  As said before oats can probably be seeded as deep as 3 inches without jeopardizing the initial stand.

Table 1 – maximum coleoptile length of different HRSW and barley varieties.
HRSW Variety
Coleoptile Length

Barley Variety
Coleoptile Length

(inch)


(inch)
Albany
1.8
Lacey
1.9
Barlow
2.1
Legacy
2.0
Breaker
2.0
Pinnacle
1.6
Faller
1.6
Quest
1.8
Norden
2.3
Rasmusson
1.7
Prosper
2.5
Robust
2.0
RB07
2.0
Stellar
1.8
Samson
2.5
Tradition
1.7
Vantage
2.9


Friday, April 10, 2015

Nitrogen Forecast for 2015: First edition April 9, 2015

John Lamb, University of Minnesota Extension Nutrient Management Specialist

Nitrogen (N) is important for corn, small grains, and sugar beet growth. This year has been OK so far. It has started to rain this week but I would not get too concerned about N losses until I see a large amount of drainage water coming out of the tile lines. In most cases the soil is on the dry side and has room to store the spring moisture. With this in mind, the chances for loss of N fertilizer are low on heavy textured soils. For growers who fall applied their N after the soil temperatures were below 50 degrees, there has been no reason to be concerned about N losses.

New nitrogen guidelines for corn grown on irrigated sandy soils

John A. Lamb, University of Minnesota Extension Nutrient Management Specialist

On March 6, 2015, revised guidelines for fertilizing corn grown on irrigated sandy soils were released by the University of Minnesota. Minnesota has about 500,000 acres of irrigated sandy soils. Corn is grown on about half of these acres in any one year. With the use of irrigation and fertilizer, sandy soils are very productive.

In 2000, the guideline for nitrogen (N) application for sandy soils was around 230 lb N/acre. In 2006, the University of Minnesota joined several North Central Land Grant Universities to develop a common method of developing N guidelines for corn. This method was called the Maximum Return to Nitrogen (MRTN). The goal of this process was to improve the predictability, involve economics, include some adjustment for the user attitude towards risk, and to use a similar method for developing N guidelines across the region. To make the MRTN method work well, a database with a large number of corn responses to N fertilizer was needed. Minnesota had a large number of response information for highly productive non-irrigated soils, but did not have adequate information for corn grown on irrigated sandy soils at the time the MRTN was first developed. Because of a lack of data specific to irrigated soils, a decision was made to use the guideline for corn grown on non-irrigated highly productive soils for corn grown on irrigated sandy soils. This was not a good decision. The MRTN economic involve the ratio of the price of N per pound to the price of corn per bushel. At the common 0.10 ratio ($0.50 N to $5.00 corn) the 2006 guideline was 140 lb N/A with a range of 120 to 165 lb N/A for corn grown after corn or group 2 crops. This was too low.

Monday, April 6, 2015

Should You Consider In-furrow Starter for Corn in 2015?

By Daniel Kaiser
Extension Nutrient Management Specialist

The use of starter fertilizer placement on the seed (known as in-furrow placement) is commonplace in many areas of Minnesota. I commonly receive questions on the value of in-furrow starter fertilizer when corn prices are low. The application of liquid fertilizer with the planter presents additional costs which may or may not be warranted depending on the year and where a field is located within Minnesota. The results of several field trials have recently been summarized in a new publication “Banding Fertilizer on the Corn Seed”. There are a few things to consider the when and what when utilizing starter fertilizer banded on the corn seed.

Ready, Set, Go.

The first spring wheat and oats have already been seeded, although winter will officially with us one more day according to the calendar. Is it too early to already be thinking spring and seeding small grains?  Federal crop insurance guidelines stipulate that small grains are insurable when planted on or after March 21.  And although this may be part of your decision process, mother nature doesn't keep a Julian calendar. So can we already seed small grains successfully?  In 2012 I write a post that describes the requirements to get small grains established successfully and quantifies some of the risks of planting early.  I have provided link to it here.

Bottom-line: The weather forecast for the remainder of the month is trending just slightly above average for both daytime highs and well as nighttime lows. If the frost has come out at least 12 inches and the soil temperatures are reaching 40 degrees F for most of the day, I think spring wheat and oats can be seeded successfully at this time.

Friday, April 3, 2015

Did my earliest seeded wheat, barley, and oats survive this latest cold snap?

The latest cold snap may have you wonder whether the earlier planted wheat and barley have a snowball’s chance in hell to produce a healthy seedling and stand?  Wheat, barley and oats do not germinate until the soil temperatures reach 40 F.  The germination process starts with the uptake of water, breaking the dormancy and starting the development of the sprout.  Once the dormancy is broken the energy stored in the seed is used for the growth and development as well as respiration (basically maintenance).  If the temperatures are low or even freezing the growth and development of young seedling slows down or even stops.  However, respiration continues albeit at a lower rate and continues to deplete the energy stored in the seed.  This will eventually decrease the vigor of the seed and may prevent the sprouted seed to produce a healthy seedling.


With the freezing temperatures the first concerns is whether this can kill the sprouted seed.  Reports from the literature indicate that sprouted wheat and young seedling will likely survive temperatures in the low twenties.  A quick first check of the color of radicle (first root) and coleoptile (first leaf) is the first step: a white and firm radicle and coleoptile will indicate that the sprout is not damaged by frost after the seed has been allowed to thaw out. . A second test to determine viability of seed is to dig up seed and bring it home, place it between moist paper towels, and keep it at room temperature.  If the seed is viable the sprouts should start to grow within 24 hours.
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