Organic fertilizers soil conditioning

How does the organic bulk of compost help to maintain fertile soil conditions ... 

Ammonium (NH4 ) may be added as a fertilizer or released during organic matter decomposition. It is the chief species present immediately after the injection of anhydrous ammonia into soil as a fertilizer. It is labile in soil in that, under aerobic, moist, moderate temperature conditions, it is rapidly oxidized to nitrite and nitrate. Ammonia may also be volatilized from the soil solution, particularly under basic soil conditions. 

Basal dressing is advisable if the results of the soil test indicate that there is an inadequate supply of nutrients in the soil. Only products specified in Annex II of EU Regulation 2092/91 should be considered for use as fertilizers and soil conditioners. If the pH is too low, the soil should be limed with up to 2000-3000 kg of calcium carbonate/ha per year (0.2-0.3 kg/m ), or with dolomitic lime if there is also magnesium deficiency. If there is not enough humus, it is advisable to enrich the soil with organic matter (see section in Chapter 4 on Organic fertilizers for soil conditioning). 

Only organic fertilizers can be used in organic farming. To make sure that the nitrogen is available to the plants at the time of greatest need, it is important to take into account the time needed to convert the nitrogen to a form that is available to the plant (speed of action). The speed of action depends on the fertilizer, the soil conditions and the weather. Farm manures can also be used, except for blueberries. Only 10% of the total nitrogen in compost and 50% of that in cattle manure can be included in the nutrient balance in the first year. In the case of other nutrients, 100% is included. 

These substances are also used as organic fertilizers. They are intended mainly for soil conditioning. They can also be used to improve composts in a natural way. 

Nitrous acid is, as already pointed out, an intermediate nitrification product formed chiefly by the bacterium Nilrosomoms from ammonia. In fertile soils the population of this bacterium is usually sufficiently large for the oxidation of the ammonia to proceed as rapidly as it is produced from organic matter. The next step in the nitrification process, the oxidation of nitrous acid to nitric acid by the bacterium Nitrobacter, is also a comparatively rapid one in productive soils. Under reasonably normal conditions, then, there is no accumulation of either ammonia or nitrous acid. Under some conditions, however, this normal oxidation process may not go to completion but il interrupted at the nitrous acid stage. 

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