THE EFFECT OF SODIUM FERTILIZATION ON THE YIELD, QUALITY AND MINERAL-COMPOSITION OF ORCHARD GRASS (DACTYLIS-GLOMERATA L)

The effect of sodium fertilization was studied in the small-plot field trials with orchard grass (Dactylis glomerata L.), the variety Roznov ska in pure culture with four-cut utilization, The trial included four treatments with four replications. To two liming methods and magnesiu m fertilization (Tuma, Matula, 1993), annual sodium fertilization in t he form of kitchen salt (Tab. I) was tested. A dose of 40 kg Na.ha(-1) was always applied too early in the spring with the first nitrogen ap plication to the first cut. Average values of agrochemical soil tests are in Tab. II. The dry matter yield was determined in each cut, along with chemical composition, including fodder-production characteristic s according to particular methodologies. Further details about the tri al are referred toby Tuma (1992). Sodium fertilization in the treatmen ts KMVR+Na and KVK+Na compared with untreated treatments (KMVR and KVK ) contributed to the significant increase of exchangeable sodium conte nt in soil, determined by the method KVK-UF (Matula, Pirkl, 1988), Sod ium concentration in soil solution increased as well. In treatments fe rtilized with sodium a lower decrease in exchangeable potassium supply and its concentration in soil solution was recorded. A marked decreas e in potassium supply in all treatments was probably due to high withd rawal of potassium, absence of potassium fertilization and due to the system of fertilization by the other cations, especially by calcium an d manganese (Tuma, Matula, 1993). In treatments fertilized with sodium statistically significantly yield of herbage was recorded in 1989, wh ile differences in yield among particular treatments were not statisti cally significant (Fig. 1). It is interesting that the highest increas e in the yields was achieved just in 1989, where the highest uptake of sodium was reported. Sodium fertilization had a significant influence on statistically significant increase in sodium content in the herbag e (Fig. 2) which was observed yet in the first year after application of sodium. The highest increase in sodium content was achieved not ear lier than in the third year (1989) in the treatment KVK+Na with an ave rage value of 1,703 mg Na.kg(-1). This content exceed statistically si gnificantly the treatment KVMR+Na with average content 1,184 mg Na.kg( -1)dry matter of herbage. In treatments unfertilized with sodium the h ighest sodium content on average was in the berbage of the third cut, while in treatments fertilized with sodium in the first cut. Sodium co ntent in the herbage and other cuts fell slowly (Fig. 3). It is eviden t from the results that sodium content in herbage greatly depends not only on sodium fertilization, but also on the system of fertilization by the other nutrients, on their content and mutual relationships in s oil. In this context, it is about potassium, which can affect the most an uptake of the other cations (Mengel, 1984; Matula, 1987). At first sight from Fig. 4 the failing proportion of potassium is evident in p articular years which corresponded with changes in content and activit y of potassium in soil. On the other hand, increasing proportion of ca lcium, magnesium and sodium is evident. After balance of relationships of major nutrients in soils which was achieved with time as late as i n 1989, the effect of sodium fertilization was manifested the most sig nificantly. Sodium was shown to be the most active cation. Thus, those conclusions were confirmed (Matula et al., 1985) that sodium content needed in production cannot be achieved without suitable adjustment of potassium supplies in soils and relationships to the other nutrients corresponded to it. Interaction in the content of different cations in herbage are in accord with conditions in equivalent statement,(Fig. 5 ). Sodium fertilization contributed significantly to the decrease in K /Na ratio. The lowest values here were recorded in the treatment KVK+N a where these values fell on average to the value 10.0, which is close to the requirements for nutrition of animals. A marked effect of sodi um fertilization was manifested also in a ratio K/Ca+Mg which also fel l in the above treatment to the lowest value 1,45 in 1989. Sodium fert ilization had no significant influence on the other conditions, e.g. K /Mg, K/Ca+Mg. Relatively high variability was recorded in nitrate cont ents, hence statistically significant difference (Fig. 6) was not foun d among different treatments. Despite it, on average lower nitrate con tent was observed in treatments fertilized with sodium. It was about i nteraction with chloride. Sodium fertilization had no significant effe ct on indicators of nutritive value of the herbage.