Potato It is one of the most widespread species in orchards, it is one of the first to be planted in the spring and it is also one of the most nutrient demanding obligatory.
This is why fertilization plays a crucial role in its cultivation: either in professional production or in the vegetable garden. If you want to get a good harvest of large and numerous potatoes, you have to pay attention to this aspect right from the preparation of the soil.
Therefore, it may be useful know how much fertilizer is necessary for a good potato field, what types of fertilizers are preferred and which periods are the most appropriate to manage them. This topic complements articles on how to plant potatoes and grow them organically.
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Fertilization of organic potatoes
In conventional farming when we talk about fertilization, we mainly refer to crop removal : in this case, how many kg of nitrogen, potassium, phosphorus and other elements are removed by growing potatoes. Based on the “expenses” per hectare, one calculates how to integrate them, using fertilizers that are often released instantly.
in a crop organic or at least durable the approach is different : the first concern is make the soil healthy and lush , because a fertile soil, rich in organic matter and micro-organisms, allows plants to grow harmoniously and give satisfactory yields. It is therefore not a question of intervening punctually in the consumption of the plant but of ensuring, by good organic fertilization, a rich and vital substrate also in the long term. Sure vegetables also have different needs and there are a few like potatoes that require more nutrition . Indeed, it must be taken into account that its crop cycle is long and therefore consume a lot of resources when growing.
What fertilizers to use
In the organic cultivation of potatoes, as in any other vegetable, only fertilizers of natural origin are used that is, organic or mineral substances, avoiding fertilizers synthesized in chemical laboratories.
Nitrogen is used for plant growth, while phosphorus and potassium are used for the proper formation of tubers, their quality and their future life, these three elements are the main ones and are indicated on the labels of fertilizers with the abbreviation NPK . However, there is also many other items which perform their important functions and are contained in organic or natural mineral fertilizers.
As we will see, the two protagonists of good bottom fertilization are generally the fertilizer and the manure , ideally equine or bovine. These products must be well matured so as not to create problems, especially when used during cultivation or near planting. worm humus it is an even better substance, and its availability is certainly worth using. To increase potassium, you can add a little wood ash to these moderate dose soil amendments.
During cultivation, it may be convenient to use granulated manure That is borage manure , rich in potassium. On the other hand, to respond to the specific deficiencies rock flour can be useful or potassium magnesium sulphate .
Fundus fertilization
Bottom fertilization Is a kind of basic nutrient which is carried out before planting the tubers, during the preliminary phase of plowing .
Remember that normally potatoes are planted in March , in the south from February and in the mountains only at the end of April, and the actual duration then depends on the weather. The important thing is that the ground has warmed up sufficiently and that the ambient temperature is at least 10°C on average. The ideal is to prepare the ground the previous fall or just before planting .
With plentiful supply from main tillage fertilizer That is manure that must be well matured . They both have the function of soil conditioners : they fertilize the soil in general, they also provide nutrients, but above all food for all soil organisms and a better soil structure. Let’s not forget that the potato must grow in the ground and therefore it must be soft. sweetness of the ground it is not only achieved with tillage, but also with the precious help of the organic substance which makes the soil more loose, especially if it has a clay texture and tends to compact.
compost or manure should not be buried deep but must be integrated into the first 20-30 cm maximum , where most of the roots are, which in this plant are grouped together and remain quite shallow. The nutrients contained in compost and manure can be transferred to the roots of plants thanks to the mineralization work of aerobic microorganisms, which are found in the surface layers of the soil where there is oxygen.
If there is no possibility of finding compost or manure, we could make a beautiful fall green manure , only that the burial of the biomass should take place earlier than usual, that is to say at least the beginning of March. Green manure is a characteristic practice of organic farming that we have explored in a dedicated article.
It would be nice to have too wood ash because it contains a lot of potassium and potatoes are very potash .
How much fertilizer to plant
As a guide we need 4-5 kg per square meter of compost or mature manure , so in 20 square meters of potatoes you need about a quintal of compost, or even a little less. It will be observed that self-produced compost is rarely enough to cover the needs of the garden and that it must most often be integrated, but fortunately, thanks to the separate collection of wet or pruned branches, there are several companies that produce compost and sell at relatively low prices, low for those who ask for them.
Ash must be spread on the ground In small quantities without exaggeration, not in a heap but by sprinkling .
seed fertilization
When planting seed potatoes it is advisable to add granulated manure to the soil or any other organic fertilizer. Let’s avoid putting handfuls of this fertilizer inside the holes dug for the seed tubers: the roots of the growing plants extend well beyond the holes, so it’s much better spread the fertilizer evenly over the entire surface interested in the harvest, more or less in the dose 3-400 grams per square meter.
When potato plants reach 15-20 cm in height it’s time for the first jam and it’s a good opportunity to spread more handfuls of natural manure which can still be normal manure granule and possibly also a natural fertilizer based on borage , which contains potassium. If the soil lacks a little magnesium, we could use natural potassium magnesium sulphate Where rock flour .
Also at the second jam what is done later with tall plants, we can intervene moderately with other natural fertilizer additions.
now in summer games are made in that additional fertilization would not bring significant improvements and the plants would begin to yellow because they complete their cycle and allocate its resources to the maturation of tubers.
This is why it is important to provide the most important nutritional care to potatoes during the first months.
Low growing pale green plants indicate the low presence of nutrients in the soil and this should not occur in organic and fertilized soils, even with natural products. This is not a disease but a fertilization problem, which cannot always be solved during cultivation, as the substances need time to become available to the roots. This is why it is important to take care of root fertilization in the first place.
unfertilized crops generally generate, as expected, small and few tubers .
For nutrients to be mobilized in the soil and available for uptake by the roots, it is important that there is occasional rain and sufficient water for the crop. Water serves plants as an element in itself and also as a vehicle for nutrients.
However, usually in the spring rains make irrigation unnecessary potatoes, unless there is a prolonged drought during the delicate flowering phase.