Kombineret plantetaetheds-, raekkeafstands- og kvaelstofgoedskningsforsoeg i majs til ensilering, 1974-78.

At Lundgard, Roskilde and Renhave six factorial-trials were carried out in 1974-75 with the forage maize variety Anjou 210. Row spacings of 25, 50 and 75 cm, plant densities of 10, 15, 20 and 30 plants per square metre and N-rates of 125 and 175 kg N per ha gave a total of 24 combinations. These trials were sown with an ordinary drill and the seed rate was adjusted to the required plant density, however, the distribution of the maize plants was not even. At the same locations similar trials were carried out in 1976-78 with the maize variety LG 11 with row spacings of 31.25 and 62.5cm, plant densities of 5, 10, 15, 20 and 30 plants per square metre and the same N-rates, giving a total of 20 combinations. These trials were sown with a special drill, the plant distribution was more even and, therefore, the results became more significant, but generally, they were in line with the results from 1974-75. The equivalent of 33 kg N and 69 kg P per ha was combine-drilled with the maize. The yield of dry matter cobs increased with plant densities between 5 and 10 plants per square metre, thereafter it decreased considerably. The yield of dry matter of stems increased from the lowest to the highest plant density, yet only just enough to neutralize the decrease of dry matter of cobs, because the total yield of dry matter increased only up to a plant density of about 15 per square metre and became almost constant at higher plant densities. By changing the row spacing from 31.25 to 62.5 cm a decrease in yield of 3.5 per cent was observed. An increase of the N-rate from 125 to 175 kg N per ha resulted only in a slight increase of total dry matter. With the greater food value of the dry matter of cobs than of the dry matter of stems and considering the above results it must be recommended when growing maize for silage under Danish conditions to aim at a plant denisty of 9-10 plants per square metre and a row spacing as narrow as possible to allow for the appropriate use of machinery, and to apply 125 to 150 kg N per ha.