Seduced by the mirage of “Organic Agriculture ” many novice gardeners think that the use of organic fertilizers is the winning solution to obtain the best crops. But things are not quite so.
The real choice in choosing the fertilizer isn’t chemical or natural but proper or improper. Like the chemical fertilizers, the natural ones are very different in chemical composition. It is necessary to know what type of manure you choose regarding the soil type and crop. Otherwise, the results will not be the desired ones: the soil will degrade, the harvest will be poor in quantity and of poor quality.
Cattle, horses, sheep, goats and birds ‘produce’ different type of manure which can not be used anyway because it has a certain concentration of nitrogen, phosphorus, potassium or calcium.
It is not the same thing if you use a “fertilizer” containing 0.5% or 4.5% nitrogen, 0.3% phosphorus or 2.7% – the differences are great.
Nitrogen, phosphorus, potassium, calcium, sulfur and magnesium are macronutrients – plants need these substances in particular.
Iron, boron, zinc, they are micronutrients – they improve plants.
Macro and micro nutrients exist in a greater or lesser percentage in the soil – the fertilizer role being to “cover” this soil deficiencies.
You first need to identify the soil weaknesses. Those are highlighted by some signs that crop show – just like sick people.
When the top of the leaf is slightly pale and the bottom part is yellow then we have a lack of nitrogen.
When the leaf tip and edges are yellow then we have a lack of potassium.
When the leaves are have a darker green shade than normal then we have a lack of phosphorus.
The “richest” organic fertilizer is the dried manure – this contains 4.5% nitrogen, 2.7% phosphorus, 1.4% potassium.
Less rich is the cattle and sheep manure – 1.9% and 2.0% nitrogen, 1.5% and 1.4% phosphorus and 2.2% and 2.9% potassium. Dried manure goes into the top rankings for having almost double content of nitrogen and phosphorus – two of the three most important macro-nutrients.
Although nitrogen is considered the growth “ingredient” – its use needs to be made sparingly and always adequately with the soil type and crop – the only one who knows is the agronomist.
The soil pH should also be taken into account – how acidic or alkaline it is because this is the main indicator that tells you what type of crop will go and what combination of nutrients will be used.
Anyway, give up the idea that if it’s “natural” it can’t harm – the acid rain is natural and is harmful – as well as fertilizers can be if they are not used properly. Not only the lack of a certain nutrient can cause harm, but also the excess.
Image Credits: Garden and Greenhouse