Applying High Rates of Liquid Nitrogen at Seeding

(Liquid Fertilizer and Direct Seeding)

Ed and Trevor Douglas

McTaggart, Saskatchewan

Farm Background

We farm 3500 acres of heavy clay approximately 10 miles northwest of Weyburn. The land is flat but well drained and the soil is typical gumbo; it rolls up very easily and is susceptible to blowing if worked extensively because of its fine textured nature. The soil also packs very hard if disturbed when moist.

Fertilizer Use History

When the family came to the farm in 1975, fertilizer use was bags of 11-48-0 (4.5 lbs.actual N, 19 lbs. P) on summerfallow and 23-23-0 (21lbs. N, 21lbs. P) on stubble applied with the fertilizer boxes on the discer at seeding. Something had to change considering the low levels of N applied constant filling and more continuous cropping being investigated.

In 1977, we tried fall broadcast 46-0-0 and spring applied 11-51-0 with the discer. The uneven application using a spreader was a major concern. The application of Avadex and Treflan using booms on the back of the discers looked promising and liquid fertilizer was compatible with these wild oat chemicals.

Liquid fertilizer was applied with tractor-mounted saddle tanks to booms located across the back of the discer in 1979. The 28-0-0 mixed with Avadex and /or Treflan was applied with this method while 11-51-0 was still applied via with the discer fertilizer boxes. This made for a busy seeding time as many different products were being handled. It was a concern that the liquid fertilizer was >trapped= in dry soil.

In 1980, fall banding liquid 28-0-0 with a vibra-shank cultivator was implemented with the advantages of a reduced workload in spring and less volatilization. The down side (at the time) was reduced flexibility in spring and more planning required (little did we know how much planning would be required in a continuous crop, intensive rotation, zero-till system.)

After investigating various air seeders and drills for a few years, we took the plunge to zero-till with an air drill in 1993. Our main reasons to switch were residue management, one-pass seeding operation, elimination of discer ridging , and ease of transport and clean-out. We had been practising continuous cropping for several years and seeding through high levels of trash was becoming our biggest problem. Looking back, it is easy to say that the number one reason for owning a zero-till machine is soil and moisture conservation. In order to continuous crop, we believe zero-tillage is essential.

Liquid fertilizer use on our farm is justified using the following reasons:

1. Custom blending. We can adjust our fertilizer rates easily for different crops, stubble types, fields, and conditions.
2. Crop safety. In 1997. We received our first rain, after snow melt, on June 28th of 7/10". With over a month of dry conditions after seeding, no crop injury was perceived.
3. Personal safety. Liquid fertilizer is safe and easy to use with little risk to personal safety.
4. Uniform blends. Liquids are easy to mix and stay homogeneous.
5. Dealer service. Our local fertilizer dealer has provided excellent service for many years.

Seeding and Fertilizer Equipment

Our seeding machine is a Flexi-Coil 5000 Air Drill on 12" spacing with the Stealth double shoot paired row boot, liquid tubes and gumbo tip. We pull a tow-behind Flexi-Coil 2320 air tank with the seed treater option and a 2800 U.S. gallon liquid fertilizer cart with hydraulic pump drive. We designed the fertilizer cart using Flexi-Coil caster wheel assembly for the front and 24.5-32 tires on the rear. With these tires, the weight per unit area is less than the air cart when full.

Our fertilizer is stored on the farm in four storage tanks. Two 14,500 Imp. Gal. tanks are used for 28-0-0, a 7,500 Imp. Gal. tank is used for 10-34-0, and a 300 Imp. Gal. tank is used for 15-0-0-20. The blend is carried to the field in two 1500 U.S. gal. poly. Tanks which are mounted on a gooseneck flatdeck pulled by a 1-ton service truck.

Double shoot equipment is essential to good emergence and seeding vigour. It also allows you to put adequate levels of nutrients with the seed in a one-pass operation. There are complaints that double-shoot openers cause higher disturbance and opener plugging in heavier soils. We have found that seeing at 4.0-4.2 mph eliminates these complaints and crop uniformity is excellent.

In the past, seeding equipment was much less expensive than harvesting equipment. The speed at which the crop was sown was of vital performance. Now our seeding equipment costs 1.5 times as much as our harvesting equipment and the travel speed of the seeding operation itself has slowed. We have compensated for the lack of travel speed by increasing the size of our seeding unit. It is important to remember that unless the seeding job is done as well as possible with every effort to reduce risk, the crop you have may not be worth harvesting.

Fertilizer Levels

The first fact to consider is that field fertilization is not an exact science. Different moisture and temperature conditions affect natural nitrogen processes. Also different types, quantities, and qualities of crops and their residues affect fertility. With that point in mind there are several ideas that affect our fertilizer levels:

1. Conversion to zero-till system. In the first few years in a zero-till system there is a noticeable lack of fertility as you wait for natural processes to >catch-up= with the residue lying on the soil surface rather than being incorporated.
2. Nutrient levels used by planned crops. In Table 1, the rates of different nutrients to produce a certain yield of crop are shown. Realistic yield goals need to be set given the moisture conditions going into the season and long term average for a particular crop in a certain area. Nutrient requirements for these yields can be estimated using this type of table.
3. Nutrients used by previous crops. When determining fertilizer levels it is also important to look at previous years yields along with previous fertilizer application levels. If a 50 bushel durum crop was fertilized at a 40 bushel level, the difference needs to be made up so the soil N pool is consistent from year to year.
4. Soil tests. Soil tests are important periodically to verify the previous three points. They are also important when there are yields that don=t measure up. Soil tests are a guideline only because of the various errors that can occur in their procedure and need to be implemented in a broad approach to fertility.
5. If unsure, we err to using higher rates. Maximum yield is determined by the fertility available in the earliest stages of crop development. Foliar applications mainly affect protein therefore proper rates have to be applied with the seed. Ten extra pounds of N only costs roughly $2.50 while representing only 2 bushel of wheat or 1/3 to 1/4 bushel of canola.

With the preceding points noted and our rotation as cereal-pulse-cereal-oilseed the following actual levels of fertilizer are commonly used on our farm.

Cereal on oilseed 60-20-0-5

Cereal on pulse 40-20-0-5

Canola on cereal 70-30-0-10

Flax on cereal 40-20-0-5

Lentil on cereal 10-20-0-5

Pea on cereal 10-35-0-5

High Rates of Fertilizer at Seeding

Our test of evaluating high rates of fertilizer at seeding consisted of several strips with varying fertilizer rates roughly 300 feet long within a field. A Karma CPS White plot was seeded into lentil stubble with fertilizer rates of 0, 40-20-0-5, 80-40-0-10, and 120-60-0-15. The other plot was Independence canola with fertilizer rates of 0, 35-15-0-5, 70-30-0-10, 105-45-0-15, and 140-60-0-20. In both cases, the fertilizer rate was varied proportionately cutting the seeding units speed.

We found with he CPS plot that there was no noticeable difference in emergence, plant density, crop maturity, or yield between the plots with N rates of 40, 80, or 120 lbs. of actual N. The canola plot was seeded on May 24 but did not emerge until the long week-end in July due to poor seeding depth (considering the lack of subsequent rainfall). Also, a poorer stand because of poor seed vigour made it more difficult to analyze the plot. However, the rates of 70, 105, and 140 lbs. of N showed no noticeable difference in emergence, density, maturity or yield. Moisture was a limiting factor in both plots throughout the year as 3-4" of precipitation was received during the growing season. The CPS yield was 37 bu/ac and the canola yield was 20.5 bu/ac.

In a zero-till system, fertility is just one of the many variables which need to be considered. With that noted, we feel that in our operation liquid fertilizer at seeding is an effective option.

Table 1 Nutrients Used by Crops

Source: Western Canadian Fertilizer Association.

Table 2. General Crop Information - Direct Seeding Experience.