From a news release
The results of the Great Lakes Grain 4th annual crop assessment tour were released on the opening day of Canada’s Outdoor Farm Show, Sept. 10. The tour took place from Sept. 3-6. GROWMARK FS members from across southwestern and central Ontario participated in the tour that compiled and analyzed 1,000 yield assessments in 13 zones. In terms of acres, we assessed approximately 35,000 of corn and 31,000 of soybeans.
The magnitude of the variation was the largest seen in four years, both within field and between fields. Excessive rainfall in some areas and moderate temperatures for the most part has slowed progress compared to the past year. We will need all of September to be frost-free to bring corn and soybeans to desired maturity.
Most sites had adequate populations and high row counts on the cobs. This is indicative of good early season growing conditions, in spite of some late frost damage. We have some of the highest kernel counts on cobs of the past four years. Large cobs are nice to see but also pose a challenge to fill them and capture the yield potential.
Two observations that dominated the trading area was widespread Nitrogen deficiency on fields that did not use protected N sources.
Secondly, drainage impacted on plant stands and overall plant populations in the most challenged fields. Nitrogen deficient leaves up to and past the cob is a good indication of limited N supply. This affects both the length of cob fill and depth of kernels for high test weight. Poor drainage simply means missing plants or plants with barren stalks and of course more nitrogen loss through denitrification.
One of the issues with large cobs is the demand for sugar to fill them. This takes sunshine and nitrogen to drive photosynthesis. Large cobs are dominating sinks and will pull sugar from the stalk when photosynthesis lags behind demand. This can lead to poor stalk quality, increase incidence and severity of stalk rots and ultimately lodging. There was a noticeable difference in fungicide treated corn in terms of canopy health and slight reduction in severity of N deficiency. Doing a push or pinch test on stalks after black layer will give a good indication of stalk integrity and which fields should be considered for first harvest.
We did notice higher incidence level of northern leaf blight this year. A combination of N deficiency, foliar leaf disease and large cobs is not the desired environment. We expect to see rather large response to fungicides this year.
There was a strong relationship to yield estimates and plant populations. The average yield of 160 bushels per acre coincided with 32,250 plants per acre. Low yielding sites this year were due to shorter cobs, more barren plants and lower populations mostly related to excess water.
Corn planted in the first week of May with current heat unit accumulations will black layer (R6) around September 20 to 25. It will take until the second week of October to lose six per cent moisture to bring harvest moisture to an estimated 24 per cent. With consideration for weak areas in fields, it is a strong corn crop.
The soybean crop is the most variable in yield. There is not one factor that stands out on explaining soybean yield but rather layers and layers of stresses. An accumulation all season long of the impact of saturated soil, root rots, low plant populations , Soybean Cyst Nematode (SCN) , Sudden Death Syndrome (SDS) , aphids, bean leaf beetle. Japanese beetle, brown stem rot, potassium deficiency, manganese deficiency, cool nights in August all contributed to the final outcome. The more of these stresses you have in the field, the greater the impact on lowering yields.
Plant populations by row spacing are an interesting observation. In other years we have not seen as big of spread on 7.5 inch rows compared to 15 inch. This year, it is likely due to population. With thinner stands, narrow rows closed sooner capturing more sunshine and producing more yield.
As weather warms, sugars will move to developing beans from the stems and petioles and size the beans. The question is how many beans will be in a pound? We used 3,300 to 3,800 seeds per pound to estimate yields. If the beans size to 3,000 seeds per pound then yields potentially increase by ten per cent or more. We are looking at a solid 40 – 45 bushel soybean crop on average based on 3,500 seeds in a pound.
The yield estimates apply to the Great Lakes Grain trading area. We are not calling this a provincial average since we have no data points from the far eastern part of the province.
One of the opportunities moving forward is to manage Nitrogen better. Managing N as a system with pre-plant, starter and side-dress, overtop broadcast with high-clearance spreaders, utilizing the appropriate strategies around protected N
sources has shown 10 to 15 per cent yield advantages.
We pay for tile whether we have it or not. There is lot of tiling going on and with good reason. 50 plus bushel corn yield differences pay for tile. It helps to reduce the temporal, or year to year variability.