Already Albrecht Thaer (1752-1828), well-known for his ‘Humustheorie’, claimed a sustainable crop production, mainly in an economical view for farmers. Later Justus v. Liebig (1803-1873), known for his ‘Mineraltheorie’, stressed the importance of an adequate mineral nutrient supply for crop production, in first place as organic fertilizers and recycled municipal organic wastes in his last edition (1876) of Agriculturchemie. Only in case that in adequate mineral nutrients were be applied by organic fertilizers mineral fertilizers should be used.
Mineral nutrients, existing in different bindung forms and thus differently plant available, are one of the main factors for a proper soil fertility and thus for growth of crop plants and a sustainable agriculture. There are various methods including soil and plant analysis available for an adequate recommendation of fertilizer application. In contrast to plant and soil analysis, the provision of nutrient balance sheets for a distinct field or region will show whether a constant nutrient status of the soil, surplus or depletion of mineral nutrients take place on a medium time scale. A nutrient surplus, often observed in industrial countries with a high livestock production, would mean a low fertilizer and also resource efficiency and often to-gether with an environmental pollution. On the other hand, also a negative nutrient saldo, called nutrient mining, as wide-spread observed in developing countries or in low-input systems like in organic farms, can be recognized as a non-sustainable situation. Rough estimation considering a distinct negative nutrient saldo will easily indicate a relative fast nutrient depletion with consequences in a decreased yield and soil degradation.
Nowadays, there are innovative fertilization techniques available which will allow a better exploitation of the physiological and genetical potential of crop plants and thus a better fertilizer use efficiency. Such techniques will include also a better integration of organic and mineral fertilization as already requested by J.v.Liebig, Further, a stronger consideration of micronutrients for an improved resistance to abiotic and biotic stress conditions can improve the use efficiency of N mineral fertilizers in the same way as the above mentioned fertilization techniques such as placement, use of nitrification inhibitors for ammonium stabilization, nutrient priming of seeds or homeopathic dosage of mineral fertilizers for stimulation of root growth and activities. An application of all these measures will guarantee the requested sustainable agriculture in future.
