- Rapeseed sowing will begin soon. Let's check how many seeds to sow per hectare.
- How much should the sowing rate be reduced or increased for early and late sowing?
Let's not rely on parcel sowing
Rapeseed units are prepared according to a standardized model in which the package is dedicated to 3 ha (1.5 million live seeds in hybrid varieties or 2 million live seeds in the case of linear varieties) or, less often, in the case of some varieties, also for 1.5 ha (0, 75 million live seeds in hybrids and 1 million live seeds in the population). And, of course, you can sow according to such an adopted standard, although this is not a very precise solution. The sowing density should not depend on how many packages we have. In fact, it must take into account varietal, genetic (linear or hybrid?), field characteristics, as well as the sowing date. And we will take a closer look at the term, because it is crucial, and the reduction or increase in density depends primarily on when we sow. The remaining features are perhaps not so much of marginal importance, but certainly less important than the term itself.
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What should be the density of rapeseed?
The assumed rapeseed population should take into account partial plant losses, e.g. during wintering. Typically, such losses are assumed to be 10-20%. So, if we assume a stocking density of e.g. 40 plants/m2, we should sow 45 – 50 plants per each meter.
Generally, in the case of linear varieties, the sowing rate is slightly higher. A sowing density of 50-70 plants is recommended. In the case of hybrids, the above-mentioned population of 40-50 plants per meter is usually recommended. In such a system, taking into account even 20% losses, the rapeseed stocking rate can still be optimal.
If we sow 50 – 70 pieces per m2 of the linear variety, even taking into account 20% losses, a good plantation density of 40 – 55 plants will be maintained. However, such a density is too large for hybrid varieties. Here, after taking into account losses, it is good if we have 30 – 40 plants / m2. We know that in a good season (with favorable weather conditions) plantations with 20 plants per m2 also performed well, although this is, in a sense, a roulette game.
Losses will be related not only to wintering, but also to how the plants cope at the emergence stage. There were years when, after sowing, there were heavy downpours that "pressed" the ground. If the stocking density is very low after emergence, we have a big problem, because further losses will probably be related to winter losses, which, given the low stocking density at the beginning of the plantation's development, can be quite dangerous.
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Rapeseed yield by region. In which region did rapeseed fall the least?
Let's adjust the standard to the sowing date
In the case of early sowing, we always use the lower limits of the recommended standards. However, even when sowing is delayed, the planting density must be increased. Recommendations are a certain indicator. Thus, in the case of a hybrid variety, sowing at an early date may involve sowing 40 plants per m2, and optimally, for example, 45. However, when sowing rapeseed at a delayed date, the standard must be higher and should be around 50 plants per m2. In the case of populations, the density should be even higher, and it must also be taken into account that linear varieties are less tolerant to delayed sowing than hybrids.
Farmers who have been sowing rapeseed for years know perfectly well that, within common sense, much more rapeseed can be sown from a theoretically 3-hectare parcel. It happens that 4 or even 4.5 ha are sown per unit. However, you need to approach the topic sensibly. The sowing unit of the hybrid variety is prepared according to the stocking density of 50 pcs/m2. So, for example, when sowing rapeseed in southern Greater Poland on August 20, we can easily sow up to 40 pcs/m2. However, if we sow after August 25, it is better to use 45 plants per m2, and in the case of sowing at the beginning of September, even 50 plants per meter.
Hypothetically: we assume the target plant population after winter at 35 pcs/m2. This means that if we decide to sow at the optimal date and taking into account a 20% loss, we sow 45 plants/sq m. However, if for some reason sowing must be postponed, e.g. by a week compared to the optimal one, we increase the standard by 10%. and we sow 50 plants. Assuming losses at this level is quite safe because it usually takes into account both post-winter losses and possible losses at the emergence stage.
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How to calculate the sowing rate?
Although the sowing density is set in pieces per square meter, technically we sow in kilograms. Here, of course, it is crucial to calculate the sowing rate according to the formula: (MTN x density) / germination strength. Therefore, assuming a mass of a thousand seeds of 4.5 g and a population of 40 plants per square meter, with a germination rate of 95%, we will sow 2 kg of seeds per hectare. This results directly from the formula where we substitute the data: (4.5 gx 40 pcs) / 95%. You can quickly calculate the sowing rate using our calculator using the link below:
https://www.farmer.pl/produkcja-roslinna/kalkulatory/kalkulator-normy-wysiewu.html
