Остання редакція: 2020-04-21
Тези доповіді
The soils of Moldova are characterized with a high fertility. The study carried out in the 1950-1960 yrs. and it demonstrated that the chernozems contained in that period 340 t·ha-1 of humus in the layer of 100 cm. There were 20 t·ha-1 of nitrogen and 5 t·ha-1 of phosphorus in the composition of organic matter. The content of P2O5 in the arable layer was 160‑180 mg and in the 90‑100 cm – up to 100 mg. Moldovan soils are rich in minerals containing potassium – the total content in soils is 10-15%. In the 1950‑1960 the plant crop harvests were modest and constituted: 1.6 t·ha-1 of winter wheat, 2.8 t·ha-1 – maize for grains, 1.5 t·ha-1 – sunflower seeds and 11.9 t·ha-1 – sugar beets.
Obtaining the high crop yields was limited by two natural factors: the insufficiency of moisture and the low level of nutrients in the soils. The possible harvests calculated according to the degree of humidity were by 60‑70% higher than those obtained of that time. The export of nutrients from the soil by crops was significant. As a result, in the agriculture of Moldova was formed a deeply deficiency of nutrients. During the considered period the deficits of nutrients per hectare annually were: 59 kg of N, 14 kg of P2O5 and 80 kg of K2O. The conducted research showed that fertilizers were effective for all crops and soils. That conditioned the accelerate rhythms of the agriculture chimization. In 1970 the agrarian sector of Moldova received fertilizers by 2.5 times more in comparison with the 1963 year. The dose of used fertilizers accounted for 62.7 kg/ha NPK. As a result, the balance of nutrients was rapidly improved. In the period of 1981‑1988 yrs for the first time in the history of Moldova's agriculture the nutrient balance became positive.
After the 1990 year, the volume of fertilizers increased substantially, reaching the minimum level in the period of 1995‑2005 yrs. There were applied about 4‑6 kg of nitrogen, 0.3-0.4 kg of phosphorus and 0.3-0.9 kg of potassium per ha. The nutritional balance again became deeply negative, of minus 30 kg of nitrogen, 21 kg – phosphorus and 83 kg – potassium. As a result, the productivity of crop plants dropped to the level of the 60 years of the last century.
In the recent years (2006-present) the volume of mineral fertilizers has increased. Currently the fertilizers with nitrogen are preponderantly applied. Practically, the fertilizers with phosphorus are not applied – the first necessary element in soils. In the last 20 yrs the dose of the applied manure in Moldova's agriculture constitutes 0.02 t·ha-1, the optimal dose being about 10 t·ha-1. The average norm of fertilizers applied in Moldova's agriculture amounted to 25 kg·ha-1 of the total dose of fertilizers about 90-95% is nitrogen one. The largest quantities of fertilizers are applied to the vegetable crops – 193, 70 and 52 kg/ha, respectively. The insufficient quantities of NPK fertilizers is applied to the cultivation of winter wheat -27 kg, maize and sunflower - 7-12 t·ha-1. The soil nutrient balance is negative, the chemical degradation of the soil takes place and as a result the harvests are small and of low quality.