During the last years, in the context of the programmes and strategies concerning the concept of sustainable development, amplification occurred in the field of scientific research aiming at obtaining non-gentropic outputs in viticulture. All the component parts of the viticultural ecosystem entered the sphere of this preoccupation, inclusively the soil, soil fertility being considered as a sine qua non premise for both the obtention of non-gentropic grape outputs and for achieving a sustainable development in viticulture.
The viticultural soils are damaged by a series of entropic disorders brought about both by natural conditions (most of the soils belonging to the slopes of the hills), and as a consequence of the irrational culture technologies which are practised. In this respect we can mention: erosion processes, earth slide, humus content diminution, soil loss of soluble fertilising matters, destruction of the granular structures, increase of the soil compression degree, decrease of water retention capacity, soil acidifying, loss of soil fauna, pollution caused by nitrates, pesticides, herbicides, heavy metals, etc.
About 4-28 m3 of the fertile viticultural soil/ha are lost each year (depending on the type of soil and on the slope), the humus reserve in soils being somehow reduced; 12-24 t/ha for 59% of the soils, 45-74 t/ha for 35% of the soils and 75-124 t/ha for only 6% of the soils.
In order to maintain an adequate fertility level of the viticultural soils, able to ensure great outputs of good quality, it is necessary to apply good practices for managing soil fertility.
Such good practices imply:
- Management of the humus reserve in the soil, which presents two aspects: (1) the maintenance of the processes generating humus reserve by incorporating vegetal and animal residues in the soil, for ensuring good quality humus, (2) in the context of the Common Agricultural Politics (2003) of the European Union, the quantity of viti-vinicultural produces is limited on the market; the quality is that which ensures the economical competing; considering this aspect, the humus reserve should be maintained within safe limits for the quality: 2-3% for the wines of current consumption, 1-2% for the high quality wines.
- Management of the alive fraction in the soil, which is achievable by (1) permanent covering of the soil with a cover of organic matters; (2) incorporation of the biomass produced in the vineyard or from other sources; (3) administering of composts including organic matters and specific inocules; bio-preparations including non-symbiotic bacteria, reduction of the annual works implying soil mobilisation, or their total elimination; quantitative diminution of the chemical synthesis products, or their elimination; soil enriching in earth-worms (Lumbricus).
- Management of the physical and chemical features of the soil, which means: (1) to stop and prevent the soil erosion process; (2) to reduce up to minimum the mechanical interventions upon the soil; (3) to limit the depth of the soil works up to 15 cm, without ploughing up; (4) to replace the nutrients (N, P, K, etc.) annually removed from the vineyard at the same time with the grape harvest, by applying fertilisation with chemical fertilisers of synthesis, in optimal economical rates (DOE) calculated by using mathematical models;(5) to introduce in the current practice the utilisation of composts; (6) to use as organic fertilisers the grapevine canes left after applying dry pruning; (7) to cover the soil of the intervals in between the grapevine rows by straw mulch or other organic stuff; (8) to introduce into the current practice the green fertilisers and the herbage in between the vines on the row (different methods).
