tailieunhanh - Soil fertility management - Part 2

Part II: Soil fertility and fertilizing 8 Introduction and nutrient balance To ensure a sufficient nutrient supply for crops, we must strive to keep an even nutrient balance in the soil. The loss of nutrients has to be minimised, and the addition of nutrients maximised in order to avoid a depletion of nutrients in the soil. | Part II Soil fertility and fertilizing 8 Introduction and nutrient balance To ensure a sufficient nutrient supply for crops we must strive to keep an even nutrient balance in the soil. The loss of nutrients has to be minimised and the addition of nutrients maximised in order to avoid a depletion of nutrients in the soil. For more information on the function of the nutrients see Part III Chapter 13 . Nutrients can be lost in the following processes removal of the harvest all of the nutrients volatilisation especially N this happens especially during burns due to the high temperatures run-off especially N fixation especially P leaching erosion all nutrients . Nutrients are added in the following processes decomposition of organic matter all nutrients nitrogen fixation only N weathering mostly K and Mg chemical fertiliser mostly N P and K rain and solid matter deposits. The removal of nutrients with the harvest is unavoidable. The higher the yield the greater the removal. In addition to the net removal of nutrients attention must be paid to the balance of organic matter as described in Part I Chapter 2. Contents 35 9 Compost See also Agrodok 8 Preparation and Use of Compost Definition Like manure compost is an ideal fertiliser. To create a compost heap organic material . crop residues straw manure kitchen wastes etc. is collected and stored together. In this heap micro-organisms decompose the material. Goal After it is spread onto a field the compost supplies nutrients and increases the level of organic matter in the soil. Local conditions In areas with heavy rainfall mulches and green manures are usually used together with permanent crops. Decomposition occurs fast enough on the field. So it is not worth the effort of composting crop residues. However composting is very suitable for dryer areas where crop residues decompose very slowly in the field. In this situation composting provides greater yields for the farmer. In very dry areas composting can be .