Why does corn need nitrogen-rich soil

Nitrogen fertilizer

That is why plants need nitrogen

Healthy nutrition is just as important for plants as it is for humans, because only those who are vital and healthy do not get sick easily. Nitrogen is vital for plants and, so to speak, the engine of growth. It is significantly involved in photosynthesis, responsible for the growth of plants and an important building block for enzymes and DNA. A deficiency quickly leads to light green leaves and clearly declining growth. Since nitrogen is mobile in the plants, the shortage begins in the lower leaves - the plant simply draws resources for the young, growing leaves and flowers and, if necessary, dispenses with old leaves. An oversupply leads to dark green, almost bluish leaves and, above all, pollutes the soil, as nitrogen not absorbed by the plants is washed out.

Use fertilizer correctly in the garden

The garden is constantly losing nutrients, lawn clippings go to the compost, fruit and vegetables end up on the plate. Regular fertilization replenishes the soil's nutrient reserves. So-called complete fertilizers with the main nutrients nitrogen, phosphorus and potassium are the main meal for the plants - and practical and above all convenient for the gardener. Fertilize once and the plants are taken care of.

Most of them, however, only fertilize by feeling - and often overdo it. As a result, many garden soils are oversupplied, especially with phosphate and potassium. Further full fertilizer portions are of no use to the plants, but damage the soil. If you regularly distribute complete fertilizer, you should occasionally call in a soil sample for analysis. The chambers of agriculture provide more information. This applies to newly acquired gardens as well as to existing vegetable patches.

In contrast, straight fertilizers contain only one main nutrient, for example nitrogen. Other nutrients such as calcium or sulfur can of course still be included. Nitrogen fertilizers specifically stimulate plant growth in spring, but also help with acute deficiency during the entire vegetation period. In this way, you can control plant growth in a targeted manner, but only supply the soil with nitrogen in a targeted manner according to a soil analysis. The nitrogen concentration in the soil is not lower because the plants absorb so much of it, but because the soil cannot store nitrogen for long. What is too much is washed out with the rain and irrigation water. Therefore, the garden should be fertilized annually with nitrogen.

Manufacture of nitrogen fertilizers

Nitrogen is abundant in the air, but the plants cannot do anything with it. It was not until 1910 that the Haber-Bosch process made it possible to bind atmospheric nitrogen in the form of ammonia and process it into water-soluble fertilizer salts. Until then, mineral saltpeter deposits and various organic substances were the only sources of nitrogen for plant fertilizers.

Legumes such as peas or beans, but also gorse and robinia are the only family of plants that can do what the Haber-Bosch process needs a lot of energy for - they use atmospheric nitrogen. The trick of these plants is a symbiosis with bacteria: special bacteria settle on the roots that absorb the nitrogen in the air and pass it on to the plants. In return, the bacteria receive energy packets in the form of organic carbon compounds from photosynthesis.

Nitrogen fertilizers contain different forms of nitrogen. But whether urea or ammonium, in the end every form of nitrogen in the soil turns into nitrate, which is the only form that is directly absorbed by the plants in large quantities. But nitrate is also the form that is washed out. Ammonium can also be absorbed by plants, but is bound to soil particles and there, for the most part, is safe from being accessed by plants. As long as the nitrogen does not turn into nitrate, the nitrogen remains in the soil and is not washed out. The long-term effect of some nitrogen fertilizers is based on this - the microorganisms need time to make the nitrogen available to the plants.

Mineral nitrogen fertilizers

Mineral nitrogen fertilizers are produced industrially and contain the nutrients as highly concentrated, water-soluble salts, so that the fertilizers work immediately. This makes the fertilizer ideal for heavy consumers. Nitrogen fertilizers also have a long-term effect when microorganisms either first have to convert the nutrients into nibbles that are suitable for plants or they are surrounded by a synthetic resin coating that gradually dissolves. If you do not adhere to the dosage recommended by the manufacturer, you risk burns. After fertilizing, water thoroughly and never fertilize in the heat - there is too great a risk of plant-damaging salt concentrations in the soil. Good mineral fertilizers are low in chloride, so the risk of root damage is significantly lower. If, as is the case with many cheap fertilizers, this is not indicated, one can assume that they are rich in chloride.

Organic nitrogen fertilizers

Organic nitrogen fertilizers consist of horn meal, animal hair or other natural raw materials that are processed industrially. In addition to nitrogen, they also provide valuable humus, which gets soil life on its toes and ensures that the soil is nice and loose. Organic nitrogen fertilizers work more slowly, but also longer than mineral fertilizers. They are intended for the basic supply and are given into the planting hole or raked under in permanent crops. Overdosing is impossible and the nutrients are not washed out.

The main nitrogen fertilizers and their properties

The following nitrogen fertilizers have proven themselves in the garden:

  • Calcium ammonium nitrate acts quickly and contains 26 percent nitrogen and 10 percent calcium. A good choice for acute nitrogen deficiency.
  • Urea (amide nitrogen) contains 46 percent nitrogen and works quite quickly. With regular administration, the pH value becomes more acidic, which bog plants particularly appreciate. Urea is also absorbed through the leaf and can be used when there is a lack of nitrogen.
  • Calcium cyanamide contains 20 to 22 percent nitrogen and 20 percent calcium. Calcium cyanamide works for four to eight weeks, depending on the temperature and soil moisture. The humus content is also important because it keeps the ammonium-producing microorganisms happy. Calcium cyanamide excretes cyanamide, which acts like a herbicide. It should therefore only be spread on bare ground for basic fertilization before sowing or planting - two weeks in spring and one week in summer. Do not step onto the area afterwards. The lime effect increases the pH value.
  • Sulfuric acid ammonia acts quickly and contains 21 percent nitrogen and 24 percent sulfur. As the name suggests, with regular use, the fertilizer makes the soil more acidic. The fertilizer is perfect for vegetables such as leeks, cabbage or onions that have a high need for sulfur.
  • Organic nitrogen fertilizers are horn shavings and horn meal, the nitrogen content in them is a good 12 percent. Horn shavings release the nutrients only after two to three months, depending on the weather - but then also for months. This makes them the perfect basic fertilizer for all crops. One to two full hands per square meter are sufficient; exact dosing is not necessary. The finer horn meal works faster, but not as long. If you fertilize with straw or wood chips, you should distribute a handful of horn shavings as a preventive measure against nitrogen deficiency.

Fertilize with nitrogen

Mineral nitrogen is ideally given in spring as a start-up aid and after a good two months again in the middle of the growing season, when the plants are blooming or about to bloom. In the case of pure sandy soils, the fertilizer application is divided again over two dates and accordingly less so that nothing is washed out. In the case of acute nitrogen deficiency, fast-acting fertilizers such as urea are used as foliar fertilizers. If you get the recommendation through a soil analysis to add 10 grams of nitrogen per square meter, you have to convert this to the respective fertilizer: Simply divide this pure nutrient requirement by the percentage on the package and multiply by 100. If you need 10 grams and use sulfuric acid ammonia with 21 percent nitrogen you need 10: 21 x 100 = 47 grams of fertilizer.