How Late Can You Add Nitrogen to Brassica

A Fertiliser Program for Cabbages

Cabbages, Cauliflowers and other leafy brassicas are notoriously greedy. When you await at the foliage volume they cram into a relatively small infinite it'due south easy to see why they have such a high nutrient requirement. It's just by ensuring those nutrients are available and other weather correct that the plants will fulfil their potential and provide the all-time possible crop.

Using the same plan for cauliflowers and other leafy brassicas as for cabbage gives good results.

Soil Testing

Ideally you volition need a soil testing kit to find out how rich or poor your soil is. A decent kit will toll around £xx.00 to £30.00 and enable you lot to test pH – acidity, North – Nitrogen, P – Phosphorus, K – Potash (Potassium) many times.

Without soil assay then you volition take to rely on your judgement as to the fertility of the soil. Even a proficient judge isn't as expert as knowing though. – Soil Testing Kits

Fertiliser Requirement of Cabbages & Other Leafy Brassicas

Although this article is targeted at cabbages, requirements are similar for virtually of the leafy brassicas similar cauliflowers, romanesco, calabrese, sprouts etc. Don't forget that requirements will also vary according to the variety grown. A modest cabbage like Minicole will need less than a quarter of the nutrients of a giant diversity like Brigadier.

Adding Manure for Leafy Brassicas

We'll start with an assumption that the existing soil is in proficient heart, fairly fertile and has a loftier pH (low acidity). Over the growing flavour your cabbages are likely to need an additional 23g/M2 of Nitrogen and 5g/M2 of Phosphorus and Potash respectively.

If yous add together a wheelbarrow load of 20Kg of rotted cow manure per square metre to the soil in the autumn this will supply an boosted 140g of nitrogen assuming the manure is approximately 0.7% nitrogen.

Past the spring the wintertime rains will take washed out 90% of the nitrogen and so the bodily additional nitrogen available will be more similar 14g which still leaves a deficit of 9g/M2 on our requirement.

The manure has probably added enough of the more than stable phosphorus and potash so the chances are it's only nitrogen we demand to worry well-nigh. Nonetheless, if yous haven't managed to obtain any manure then y'all'll need to utilize a general purpose fertiliser like fish, claret and bone or Growmore in the spring. Fish, blood & bone is unremarkably 5:five:five which means v% of each major nutrient, Growmore seven:7:7 which is seven%

Applying 100g / M2 of fish, blood & bone or 70g / M2 of Growmore will supply the required potash and potassium but still leave us some 9g / M2 below the level the manure would have achieved, giving a total deficit of some 18g / M2

Organically you tin can comprehend this 18 grams per square metre using dried blood (which is 12% nitrogen) or pelleted craven manure which is 4.5% nitrogen. Artificial fertilisers similar sulphate of ammonia run at xx% nitrogen but for brassicas I use nitro chalk at 27% as information technology also contains some lime, property up the pH which is groovy for brassicas.

Now if you apply all the required nitrogen in ane go at the beginning of the flavour, the rains will wash out a substantial amount over the season. So the efficient mode is to add the additional nitrogen fertiliser in smaller amounts at intervals.

Lets presume your multifariousness volition take some 20 weeks to mature from planting out. You could add roughly a gram of nitrogen per M2 a week just realistically it'southward probably best to add together a third at planting time, a third half dozen weeks later on and the last 3rd 12 weeks after planting.

How to summate the additional amount of nitrogen (or other major food) required from fertiliser.

All fertilisers sold in the Uk volition state the North:P:K on the purse as a percentage. I.e. 5:5:5 or 15:7:3

The formula for the calculation is: Amount of required nitrogen divided by nitrogen pct in the fertiliser times 100.

So to add together viii grams of nitrogen from stale blood would be eight / 12 Ten 100 = 70 grams but to add that same 8 grams of nitrogen from craven manure pellets would be 8 / 4.5 X 100 = 178 grams. Nitro chalk would be viii / 27 10 100 = 30. All results rounded to nearest gram.

Do remember that over-use of fertilisers will not produce better results than supplying the optimum amount. Over utilize but costs more money, uses up valuable resources for no benefit and tin impairment the environment. Excess amounts of nitrogen can consequence in soft sappy growth which encourages aphids and other pests.

Further Information on Growing Brassicas

thomasbutful.blogspot.com

Source: https://www.allotment-garden.org/vegetable/brassica-information/fertiliser-requirements-cabbages-leafy-brassicas/

Share this post