Are Double Crop Soybeans Following Wheat Harvest in Your Plans?
The unprecedented price of soybeans has fueled considerable interest in double cropping soybeans. As winter wheat comes off there are a number of factors that should be considered. Since half the growing season is over by mid-July double cropping soybeans in Ontario is risky and not covered by crop insurance. Double cropping has been tried numerous times with variable success. The main risk is that soybeans planted so late will not mature in the fall or yields will be extremely low.
Moisture for germination, rains during seed fill, a warm summer, and an open fall are all necessary to make double cropping a success. Areas with less than 2900 CHU’s have little chance of success. A yield goal of 30 bu/ac is achievable in the southwest if the weather co-operates and seeding is finished by July 1st, but each day seeding is delayed reduces yield potential by 1 bu/ac per day. Seeding after July 15th is rarely successful. This means that beans should be seeded as quickly as possible after wheat harvest. Every day matters.
Do not delay in getting straw baled. Although baling the straw is recommended, if chopping and spreading the straw make sure that the straw is evenly spread across the entire width of the combine header. Regardless of your plan for the straw ensure that the chaff is well spread. Dropping a heavy mat of straw directly behind the combine will impede no-till planting and cause uneven germination. Do not till the soil as it delays planting date, removes moisture, and stimulates weeds.
With considerable wheat lodged this season, harvest might be delayed, further delaying soybean seeding. Furthermore, if lodged wheat was not effectively combined, there could be mats of straw laying on the field. Planting into such conditions will reduce soybean plant stands. High soybean populations are critical to achieving good yields when double cropping. Check fields that lodged carefully before committing those to double cropping.
While many parts of the province have received rainfall over the last few weeks, there are still parts of the province with less than desired soil moisture. Moisture is essential for germination and emergence. Ensure you are using a well-maintained, high quality no-till drill. With hot temperatures and dry winds common in July, it’s imperative that the drill closes the seed trench. If closing is not adequate the seed will quickly desiccate or the soil moisture around the seed may be adequate for germination but not for emergence.
Since soils are warm it is acceptable to seed soybeans up to 3 inches when double cropping to ensure moisture. If surface soils are moist, planting shallower will speed emergence. If conditions are dry you have to make the difficult decision to plant or wait for moisture. In most cases the best advice is to plant immediately to 1 inch and wait for rain. Given the time of year and thus the warm soil temperatures, germination and emergence will happen quickly as long as the seed has access to moisture.
A lack of moisture will lead to reduced plant stands, seldom a complete failure of the soybeans to grow. Poor stands will result in very poor yields. Consider all your costs when making the decision to plant. Is the cost worth the potential payback. At a minimum you will end up with a cover crop, so even if there is no seed to harvest some benefit will still be achieved. Bear in mind that the harvest date will be delayed, and this could result in soybean and corn harvesting needs occurring at the same time.
Seed at least 250,000 seeds per acre in 7.5” rows (see Figures 1 & 2). Select a variety that is at least one full maturity group shorter than what is adapted for your area. The genetics of shorter season varieties has greatly improved in recent years and this will improve the chances of the crop finishing in the fall. Do not count on shortening days in the fall to finish an adapted or long season variety. Although soybeans are photo-period sensitive, experience has shown a full season variety will not mature before a killing frost.
Weather Data
| Location | Year | Weekly
June 28 – July 4 |
Accumulated | ||||||
| Highest Temp (°C) | Lowest Temp (°C) | Rain (mm) | Rain (mm) April 1st | GDD 0C April 1st | GDD 5C April 1st | CHU May 1st | |||
| Harrow | 2021 | 32 | 11 | 9.2 | 242 | 1443 | 987 | 1344 | |
| 2020 | 33 | 17 | 0 | 210 | 1314 | 870 | 1309 | ||
| 2019 | 32 | 15 | 4.2 | 316 | 1259 | 812 | 1147 | ||
| Ridgetown | 2021 | 32 | 9 | 6.1 | 240 | 1356 | 908 | 1268 | |
| 2020 | 33 | 13 | 0 | 171 | 1240 | 811 | 1234 | ||
| 2019 | 31 | 12 | 6.6 | 280 | 1191 | 747 | 1080 | ||
| London | 2021 | 31 | 11 | 11.4 | 214 | 1347 | 905 | 1242 | |
| 2020 | 33 | 14 | 0.1 | 195 | 1189 | 762 | 1155 | ||
| 2019 | 31 | 12 | 11.2 | 301 | 1104 | 685 | 1015 | ||
| Brantford | 2021 | 32 | 12 | 22.5 | 205 | 1337 | 892 | 1230 | |
| 2020 | 34 | 15 | 0 | 159 | 1188 | 767 | 1141 | ||
| 2019 | 32 | 11 | 8 | 274 | 1149 | 717 | 1071 | ||
| Welland | 2021 | 32 | 12 | 7.1 | 129 | 1325 | 876 | 1216 | |
| 2020 | 31 | 16 | 0.6 | 184 | 1224 | 796 | 1200 | ||
| 2019 | 31 | 13 | 9.8 | 300 | 1211 | 764 | 1126 | ||
| Elora | 2021 | 29 | 12 | 6 | 167 | 1219 | 784 | 1121 | |
| 2020 | 30 | 14 | 0 | 157 | 1090 | 688 | 1060 | ||
| 2019 | 30 | 10 | 20.4 | 324 | 1050 | 627 | 984 | ||
| Mount Forest | 2021 | 29 | 10 | 11.3 | 175 | 1227 | 795 | 1138 | |
| 2020 | 29 | 14 | 0 | 204 | 1077 | 688 | 1065 | ||
| 2019 | 30 | 11 | N/A | 129 | 1028 | 614 | 967 | ||
| Peterborough | 2021 | 30 | 10 | 29.5 | 161 | 1213 | 767 | 1108 | |
| 2020 | 31 | 13 | 0 | 135 | 1100 | 690 | 1072 | ||
| 2019 | 31 | 10 | 1.4 | 292 | 1049 | 622 | 951 | ||
| Kingston | 2021 | 30 | 12 | 4.2 | 131 | 1239 | 793 | 1120 | |
| 2020 | 31 | 15 | 3.2 | 186 | 1194 | 761 | 1166 | ||
| 2019 | 30 | 12 | 8.6 | 290 | 1157 | 713 | 1068 | ||
| Kemptville | 2021 | 32 | 11 | 4.6 | 172 | 1333 | 880 | 1197 | |
| 2020 | 31 | 13 | 0.6 | 131 | 1153 | 731 | 1121 | ||
| 2019 | 32 | 12 | 31.1 | 203 | 1096 | 670 | 1001 | ||
| Earlton | 2021 | 28 | 10 | 41 | 218 | 1138 | 711 | 1015 | |
| 2020 | 32 | 10 | 7.7 | 218 | 936 | 596 | 958 | ||
| 2019 | 32 | 11 | 0 | 294 | 817 | 464 | 781 | ||
| Sudbury | 2021 | 27 | 12 | 12.9 | 194 | 1151 | 724 | 1039 | |
| 2020 | 34 | 14 | 10.1 | 198 | 993 | 629 | 1002 | ||
| 2019 | 31 | 11 | 0 | 271 | 818 | 465 | 764 | ||
| Thunder Bay | 2021 | 34 | 8 | 5.2 | 223 | 1017 | 604 | 934 | |
| 2020 | 34 | 11 | 12 | 92 | 894 | 550 | 906 | ||
| 2019 | 30 | 10 | 29.4 | 204 | 717 | 371 | 650 | ||
| Fort Frances | 2021 | 33 | 9 | 1.1 | 158 | 1084 | 665 | 1046 | |
| 2020 | 33 | 11 | 4.4 | 161 | 1010 | 638 | 1025 | ||
| 2019 | 30 | 7 | 18.2 | 159 | 856 | 480 | 797 | ||
| Report compiled by OMAFRA using Environment Canada data. Data quality is verified but accuracy is not guaranteed. Report supplied for general information purposes only. An expanded report is available at www.fieldcropnews.com. | |||||||||