Hudye Soil Services of Norquay, Sask. has been running its “Field of Dreams” trials for 10 years. The goal is to find out how high they can push wheat yields, and then find a happy medium between yield potential and maximum profits. In 2008, they grew AC Superb and CDC Go hard red spring wheat varieties. The Go yielded 95 bushels per acre compared to 80 bushels for Superb with the same fertility inputs.
This leads right into tip number one. Braden Hudye, vice-president of Hudye Soil Services, says they start with detailed analysis of average yearly rainfall and heat units for the farm. Then they pick varieties that work the best under these average circumstances. It would seem that Go is better suited to their conditions than Superb. Variety analysis, both through on-farm comparisons and with visits to other trial sites, is something Hudye Soil Services does every year.
Once you recognize the limitations of your fields and your local climate, set yield goals and then fertilize accordingly. Soil sampling is essential to know the baseline nutrient levels in your soils. Phil Parker is an agronomist for Hudye Soil Services and associate agri-coach with Agri-Trend Agrology. He did sector sampling in 2008 on Field of Dreams fields, sending in a separate soil sample for every 10 acres. He records the GPS co-ordinates for each sample site so he can return to the same spot every time. For 2009, he will shift from grid sampling to focus more on management zones within the field. These zones will be based on yield potential variability within the field.
Sampling by grid or management zones means 16 samples or so per quarter section. Parker says you can get by with an accumulated sample where you mix them all and send one representative sample for the field. If you go back to the same sample locations every time, you’ll get a strong benchmark for the field. “Every farmer should have those benchmarks,” Parker says.
With your yield goal set and your soil test results in hand, you can use mathematical calculations to set your fertility rates. For example, a 75-bushel-per-acre wheat field will need 2.6 pounds of nitrogen per bushel. “This is a ballpark number,” Parker says. “It will vary somewhat for each field based on seed variety, environmental conditions, soil type, and fertilizer type, method and timing.” Using the 2.6 number, a 75-bushel wheat crop will take up 195 pounds of nitrogen per acre. Subtract from that your residual nitrogen in the soil (determined by the soil test) and an estimate of nitrogen release by decomposing organic matter, and you can calculate the required fertilizer rate to match your yield goal.
Parker sets a sulphur rate for wheat based on a ratio of 10 parts nitrogen to one part sulphur.
The ballpark for phosphorus is 0.8 pounds per bushel of target yield. Only 0.5 pounds is removed with the grain, so there should be some returned to the soil every year. But in low phosphorus testing soils, Parker usually sets his fertilizer rates at around 0.8 pounds per bushel regardless of soil reserves to be sure the crop gets what it needs.
And the number for potassium is 1.6 pounds per bushel. Only 0.4 pounds of potassium is removed in the grain, so a lot is returned each year in the straw. Also Prairie soils, historically, have had high potassium reserves. But after years without applying potassium fertilizer, “potassium availability on some farms will not be as high as farmers think,” Parker says.
Then there are all the required micronutrients to consider. The goal is balanced nutrition, Parker says. “If you apply so much nitrogen, for example, that it throws the other nutrient requirements out of balance, you really are wasting money,” he says.
The next major step in the Field of Dreams wheat program is tissue testing. Parker will take 50 or 60 whole plants at the four-leaf stage and send them to A&L Labs in Ontario for tissue testing. He collects these samples from the same places he takes soil samples. Then at the flag leaf stage he’ll send in 50 or 60 flag leaves for analysis.
The goal here it to identify nutrient deficiencies while the crop is growing. That way there is still time to correct a problem in time to benefit the crop. In most cases, he will top up with micronutrients such as copper, zinc and manganese, not the macronutrients. I asked whether this was something that the average commercial farmer would see a benefit from. Parker says a tissue test will cost around $60 for the whole field. A soil sample will be $150. “This is about the cheapest return on investment,” he says, especially if it means you’re setting nutrient rates to match the target yield — which is based on the most profitable return — for the crop.
Finally, Parker says the “best and most basic” step is to get out and spend some time in the field. Use a handheld GPS to check the same spots where you’ve done soil and tissue samples. Isolate problem areas, then ask an agronomist to give some advice on how to correct them.
What should a farmer look for? “Anything. Emergence issues. Leaf colour variability. Organic matter differences,” Parker says. By noticing these differences, you can start to do more analytic work to find out why these differences are occurring and what you can do to improve your management.
Jay Whetter is editor of Grainews.