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Top Four Production Tips For Soybeans – for Feb. 7, 2011

Welcome to part two of a two part series on soybean production in Western Canada (part one ran on the cover of the January 10 issue of Grainews).This article delves further into a few of what I consider important production issues you may run across in growing soybeans, and will help you fine tune your production whether you are new to the crop or a more seasoned grower.

CONTROLLING ROUNDUP READY VOLUNTEERS

One of the major problems with growing glyphosate tolerant soybeans are glyphosate tolerant volunteers. Economically, they can seriously affect yield as nothing will grow around them and cosmetically it’s a real eyesore when the yellow starts showing up mid season.

In researching this article I came across a paper put together by the Canola Council of Canada on the topic of canola volunteers ( www.canolacouncil.org/uploads/managing_ vol_canola. pdf). The paper mentions studies conducted at the University of Saskatchewan showing that although most of the canola seed left over from previous harvest operations germinate in the first two years, there is still enough seed left to easily germinate one to two plants per square foot in year three. Canola seed can also go into a second dormancy and remaining viable in the soil for five years or more.

Two obvious ways of controlling glyphosate tolerant volunteers are rotation and minimizing harvest losses by swathing on the earlier side, timely harvest operations and proper combine settings to minimize shelling.

There are several registered options available in Western Canada for pre-seed control of volunteer canola. Unfortunately none of the options offer any residual activity to control volunteers later in the season.

In-crop options available to us in Western Canada generally fall under the Group 2 category so they require that the canola be small for good control. It should also be noted that these in-crop options are not cheap and would negate most of the economic benefits of growing glyphosate tolerant beans.

There are other viable control options registered in Ontario and in the Northern United States that are not available to us in Western Canada. While I do not recommend using un-registered products, hopefully these options will be available to us soon as the demand grows.

If you suspect that you could potentially have glyphosate tolerant volunteer issues, be sure to scout your fields early to avoid dealing with surprises later when the canola is too big to effectively control.

SOLID-SEEDED, NARROW OR WIDE ROWS?

With most soybean acres grown in areas suitable for corn and edible beans, many farmers are dabbling with row cropping soybeans because they already have the equipment. The jury is still out with what is the proper row spacing but I will attempt to summarize advantages and disadvantages to solid seeded, narrow and wide rows.

1) Solid seeded, targeting, 200,000 to 220, 000 plants per acre

This is the most common practice because it can be done with regular seeding equipment. Weed control is typically better because the beans are quicker to cover the ground. In some cases late season frost tolerance is improved because there is better heat retention within the canopy if there is full closure.

One of the biggest disadvantages to solid seeding is a higher seeding cost due to required plant populations. Less air movement through the canopy can increase the severity and development of white mold (sclerotinia). Solid seeding was originally thought to result in higher podding because of increased plant competition and higher seedbed utilization. Recent research is indicating that wider rows result in higher podding due to the plants being spaced closer together in-row.

2) Narrow Row: (15 to 22 inches), targeting 175,000 to 200,000 plants per acre

More common in the sugarbeet and corn producing areas, narrow rows can be thought of as the happy medium between wide rows and solid seeded. Advantages include lower seeding costs and slightly better disease control when compared to solid seeded.

3) Wide Row: (30+ inches), targeting 150,000 to 175,000 plants per acre

Wide row soybeans are most typically found in areas at high risk of disease pressure. These are fields with high fertility, good moisture throughout the season and little wind movement. Beans on these fields typically grow quite tall and have a tendency to lodge. The biggest advantages to wide rows are lower seeding rates and better air movement through the canopy. Disadvantages include less efficient use of the sun, tougher weed control and increased susceptibility to late season frosts.

INOCULANTS

Inoculants come in three principal forms. Preference will generally depend on equipment available to the farmer. It’s common practice to double up inoculants on first-year fields to increase the chances of successful inoculation. When doubling up inoculants, farmers will often apply a granular inoculant to encourage nodulation on the lateral roots and a peat or liquid to encourage nodulation on the main root. Peat and liquid inoculants are applied on the seed and granular is applied through one of the dry tanks on the air seeder. If you are limited with a two compartment cart you have to choose between applying a granular inoculant or starter fertilizer. The salts in most commercial fertilizers have a negative effect on rhizobia so blending them is not an option. If you want both, you may have to look at applying your fertilizer prior to seeding.

There are some newer inoculant products on the market that claim to have a plant health promoting effects. With the cool springs and short growing season we face here in Western Canada, this could prove to be an advantage. Ask your agronomist about these.

STARTER FERTILIZER

Soybeans can benefit from starter fertilizers if residual soil levels are low. Two important nutrients to soybeans (or any other crop for that matter) early in the season are nitrogen and phosphorus.

While soybeans have the ability to fix their own nitrogen with the help of inoculants, it’s a good idea to have some available early in the season before the soybeans and rhizobia have a chance to get going. Aim for between 40 and 60 pounds of N available to the crop. If N levels are any higher, nodulation can be delayed until later in the season, possibly affecting yield.

When it comes to phosphate, soybeans respond better to residual phosphate than fertilizers applied the year of but if your residual levels are low (less than eight ppm), there is a very good chance of getting a response to banded starter P.

We are limited to how much P we can place in the seed row. In most cases, the maximum amount in the seed row you can put down is 10 pounds of P2O5 per acre if your seed row spacing is less that 15 inches and you have good spring moisture. Wider rows will accommodate less. P should be banded below or to the side of the seed row for maximum efficiency. Some farmers elect to build soil test P levels in the years prior to soybeans, but in our clay soils P has a tendency to get tied up right away and benefits are limited.

Slow release fertilizers such as Micro Essentials S15 and MESZ are showing improved seed safety and allowing for higher rates to be placed with the seed. Have a discussion with your local agronomist or retailer to find out if these products are a fit for your operation.

A soybean plant’s ability to grow and perform under a variety of weather conditions and its low input requirements make it a good risk management tool in rotation. The biggest limitations to soybean production on the Canadian Prairies are heat units and frost free days, but as shorter season varieties are developed, expansion outside of traditional growing areas will continue.

Finally, potential problems with glyphosate tolerant volunteer canola cannot be ignored. If you are looking at growing soybeans on you farm this year, be sure to talk to your local agronomist or other growers in the area with experience in growing soybeans to evaluate if it has a fit and what your biggest risks might be.

BrunelSabourinisalocationagronomist withCargillAgHorizonsandbasedoutof Morris,Man.Contacthim204-746-4743or [email protected]

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