Dynamika plonowania i jakości runi łąki górskiej w okresie trzydziestu lat trwania doświadczenia nawozowego
AbstractChanges occurring over a long period of time in the productive potential of a mountain meadow and in the rnacroelement content of its sward were analysed to see if there is a possibility of using such a meadow for many years, based exclusively on mineral fertilisation, and maintaining its productivity without lowering the quality of sward yields. Data from the fertiliser experiment set up in 1968 on a mountain meadow (720 m a.s.l.) in Czarny Potok near Krynica (20°8"E; 4904"N) were used. The mean rainfall total amounted to 820.1 mm annually and to 538 mm for the period April—September, the mean temperature for the same periods being 5.7 and 11.7 °C, respectively. The experiment was conducted on the acid brown soil having the granulometric composition of a light loam and three characteristic horizons: AhA (0-20 cm), AlThr (21-46 cm) and BbrC (47-75 cm), and comprised objects fertilised with two nitrogen forms (ammonium nitrate and urea) at two rates (90 and 180 kg N ha'') against the background of PK fertilisation, an object not fertilised and objects fertilised with P and N. For 30 years (1968-1997) the effect of varied levels of NPK fertilisers on the dynamics of yielding and the changes in meadow sward quality and in selected physico-chemical properties of soil were investigated. In the objects under study the same treatments were applied, such as changes in fertiliser type and time of application, repeated liming, break in fertilisation, two-year pasture utilisation. This paper presents the dynamics of changes in the botanical composition and the yielding potential of grassland as affected by regular mineral fertilisation and liming. Particular attention was paid to the following issues: the ratio of the highest yield of sward to its lowest yield, the uniformity of yielding over a long period of time, the effectiveness of fertilisation, the changes in the nutrient content of meadow sward and in the selected quality properties of its yield. An attempt was made to justify the need for respecting the principle of sustainability in the system of farming on mountain meadows. It was found that under mountain conditions the application of nitrogen at a rate of 90 kg N • hse-1 against the phosphorus and potassium background and the regular liming of the meadow make it possible to maintain or increase production over a long period of time (at such a manner of fertilisation the mean long-term yields of meadow sward were 5.7 t of dry matter per hectare), to decrease production risk and to prevent degradation of the environment and natural resources. This is justified by the varied botanical composition of sward, stability of yielding, uniform ratios of the highest to lowest yields, chemical composition of sward and physico-chemical properties of soil. Regular preservative liming and differentiation of fertilisers areabsolutely necessary even with nitrogen fertilisation maintained at such a low level. It should also be borne in mind that the productive potential of a meadow cannot be the basic criterion of its utilisation. In terms of the long-term element balance of the mountain grassland, the creation of the monoculture of Holcus monis L., resulting from intensive fertilisation, is a disadvantage as it leads to severe soil depletion in the layer penetrated by the roots of this grass and to a gradual decrease in yields with a positive NPK balance and a weak reaction to liming. Unfavourable changes in the floristic composition of sward, caused by NPK fertilisation, can be eliminated by repeated liming whose effect on this composition is the stronger, the smaller is the nitrogen dose. The drop in yields as a result of the break in fertilisation is considerable, increases with time and becomes especially pronounced under unfavourable climatic conditions. The possibility of restoring the productive potential of the meadow sward after fertilisation resumption depends mainly on the habitat formed as a result' of prolonged fertilisation and utilisation, as evidenced by greater yield increments obtained after the resumption of fertilisation in the objects with complete mineral fertilisation applied earlier. The fall in the nutritive quality of plant communities formed under the influence of fertilisation of the meadow sward may result from the increased concentration of one element in the sward caused by regular fertilisation, accompanied by the depletion of soil nutrients not introduced with fertilisers. The amount of calcium and sodium taken up by plants decreases as the years. go by, while the content changes of other microelements fluctuate. Long-term mineral fertilisation causes a continuous increase in the value of the ion ratio K : (Ca + Mg) and K Na. As a result of the decreasing calcium availability at a relatively constant uptake of magnesium and phosphorus, the value of Ca Mg and Ca : P ratios steadily narrows. These changes are faster than those of the productive potential and show a smaller variability between years. The relations of calcium and phosphorus to copper, zinc, manganese and cadmium, occurring in the meadow sward, indicate that it is deficient in cadmium and contains an excessive amount of manganese and cadmiUm. Liming proves to have a beneficial effect on the maintenance of the nutrient balance of sward. Due to the simplified botanical composition of sward, the increase in its calcium content is low and the relation of calcium to other elements does not change remarkably. Considering the long-lasting processes of meadow plant succession and the changes in soil properties, liming should be applied before the meadow reaches its highest productive potential. This would make it possible to maintain optimal parameters of fodder quality. As a result of liming the exchangeable calcium content of soil increases and equalises between fertiliser combinations. The worsening of unfavourable physicu-chemical soil properties caused by mineral fertilisation, in particular the increase in soil acidity, can be prevented by periodic liming. This treatment should be considered as an indispensable measure designed to maintain the long-term nutrient balance of plant communities and as a starting point for other treatments stimulating yields.
|Other language title versions||Dynamics of yielding and quality changes of mountain meadow sward over 30 years of fertiliser experiment|
|Publisher||Uniwersytet Rolniczy im. Hugona Kołłątaja w Krakowie, MNiSW |
|Publishing place (Publisher address)||Kraków|
|Book series /Journal (in case of Journal special issue)||Zeszyty Naukowe Akademii Rolniczej im. H. Kołłątaja w Krakowie. Rozprawy, ISSN 1233-4189, (0 pkt)|
|Publication size in sheets||9.5|
|Citation count*||15 (2016-05-22)|
* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.