EFFECTS OF FERTILIZATION IN LONG-TERM TRI ALS ON BROWN FOREST SOIL INGODOLLO .2. PLANT NUTRIENT CONTENTS

The methods and conditions of the multifactorial small-plot experiment underway in Godollo since 1972 were reported in Part I of this paper (Kovacs K.-Fuleky Gy.: 1992. Effects of fertilisation in long-term tri als on brown forest soil at Godollo. I. Yields of arable crops. Noveny termeles. 41. 6: 533-546) together with the major agronomic observatio ns made during the first two decades. The present paper deals with the effect of long-term fertilisation and its temporary suspension on the nutrient contents of winter wheat, maize and potatoes. The primary pl ant nutrient contents in the grain yield of winter wheat, averaged ove r years and fertiliser treatments, were in agreement with average lite rary data. As the result of high fertiliser rates only the N content s howed a significant increase of 0.2-0.3 absolute %, 2nd this only for one variety (Mv 8). At the same time there was a substantial rise in t he Mn content of the grain as the fertiliser rates increased, while th e Ca and Mg contents decreased considerably. The suspension of high ra tes of fertiliser led to a reduction in the Mn content. The NPK and Mn contents in the straw showed a more pronounced rise as fertiliser rat es were increased and a sharper drop when fertilisation was suspended than those in the grain. The decrease in the N content was more intens e, that in the PK content moderate, while that in the Mn content was c onsiderably delayed. This means that the effect or after-effects of fe rtilisation on the concentration of plant nutrients within the wheat p lant were exhibited most strongly in the composition of the by-product s and had the most lasting effect on the Mn content of the latter. As regards the composition of maize grain and straw yields, year and fert iliser effects caused a moderate increase in the N content of the grai n and a consistent, substantial rise in the Fe and Mn contents. At the same time, there was also a significant increase in the N, K and Mn c ontents of the stalk, while the Mg content decreased. When fertilisati on was suspended, no great difference was observed in the element cont ents of the grain, but the after-effects of fertilisation were manifes ted to a greater extent in a slight rise in the NPK content of the sta lk, while the Mn content, which had risen in previous years due to the excessive fertilisation, showed a decline. Among the primary year eff ects, increasing rates of fertilisation caused a substantial increase in the N, K and Mn contents of potato tubers, while a suspension of lo ng-term high rates of fertiliser led to a reduction in the N and Mn co ntents. The after-effect of K proved to be more lasting. The biologica lly characteristic nutrient contents of crops are determined not only by the dominant climatic conditions, but also by the level of the nutr ient supply. They are also influenced by variety traits. As a result o f this, it is mainly the composition of the vegetative organs (straw, stalk, tuber) which increases as the result of excessive fertilisation and decreased when fertilisation is suspended. Regular high rates of fertilisation on the brown forest soil of Godollo led to and intense i ncrease in the Mn content of the grain, straw, stalk and tuber yield, probably due to Mn mobilisation induced by the gradual acidification o f the soil, while the Ca and Mg contents decreased. This may influence the value of these products as foodstuffs or animal feed or for local recycling to improve soil fertility.