In order to examine the application time of nitrogen given to cereals, several tests have been arranged on the Kotkaniemi Experimental Farm at Vihti ever since 1965. The tests have been carried out on solid clay soils, where the leaching of nitrogen has been expected to be slow. In spring cereals the autumn application of nitrogen in November on frozen soil has given a good crop yield. The protein content of the crop in the plots where nitrogen was given in autumn was lower than in those where the spreading took place in spring. As for winter wheat, application in December has given the best average crop yields but the decline of the protein content is to be considered a disadvantage. In rye, spring fertilization has given the best average crop yield. There has, however, clearly been less lodging in autumn applications than in plots where the nitrogen was spread in the spring. Regarding nitrogen fertilization of autumn sown plants the usual custom in Finland is to give nitrogen in autumn for growth during the autumn and in the spring for the coming growing season. However, as low rainfall is typical ofthe Finnish spring, the effect of nitrogen given by broadcasting in early summer is slow, especially on solid soils like clay. As for spring cereals, the fertilizer placement at a depth of 8 to 10 cms has given distinctly better results than broadcasting and the usual mixing into the soil (Elonen 1967, Larpes 1966 and 1968, Nieminen 1967, Pessi 1970). The difference in the growth intensity has most clearly been evident in the early development of cereals. Simultaneously it has become clear that the placement of nitrogen has been of the greatest importance (Pessi 1970). As during winter in Finland the soil is usually frozen and covered with snow, no noteworthy leaching of nutrients takes place. On the basis of the results and observations mentioned above the question are as to what it would mean in practice in solid soils if the nitrogen was spread already before snowfall or on the snow, when the water from the melting snow would in spring cause the nitrogen to penetrate the soil. For this purpose tests were started on the Kotkaniemi Experimental Farm of Rikkihappo Oy in autumn 1965.
Influence of intra‐row cruciferous surrogate weed growth on crop yield in organic spring cereals
