The effect of method of fertilizer application on sugar beet yield, yield quality and fertilization requirement in Finland

Abstract

In 1982—1990, the Sugar Beet Research Centre conducted a total of 68 fertilizer placement trials. The present paper deals with 23 trials from five field experiment series. In the evaluation of the results, other experiments conducted at the Sugar Beet Research Centre have also been referred to. The field trials were conducted on experimental farms of the Sugar Beet Research Centre and of sugar factories. The soil type of the experimental fields varied from compact clay to finesand. The soil pH was high (6.7 —7.4) and the nutrient status good. The fertilizer used was an Na-containing compound fertilizer (N 13 %, P 6 %, K 9 %, Na 6 % in 1982—1987; N 15 %, P 6 %, K 8 %, Na 5 % as from 1988). The fertilizer was applied with a fertilizer drill. A disk bill was used in 1982—1983; thereafter a thin spring tine bill was used. Placement of fertilizer 3—6 cm to the side and 3 cm below the seed increased the root yield of sugar beet by 5—6 %, on an average, as compared to broadcasting. The yield increase ranged from 0 to 24 %. The yield increase from fertilizer placement correlated negatively with the sugar beet yield level. The nutritional status and humus content of soil, and soil type did not affect the yield increase from fertilizer placement. The seed bed preparation one-pass power harrow or conventional method had no significant effect on the yield increase from fertilizer placement. Increasing the level of fertilizer reduced the yield increase from fertilizer placement in some of the trials. This was not always the case, however. Placement usually gave a slightly higher sugar content than did broadcasting. Placement reduced the potassium content of the beet slightly and increased the extractability of sugar. As compared to broadcasting, placement increased the recoverable sugar yield relatively slightly more than the root yield. Placement of the fertilizer 3 cm to the side (3 or 6 cm below the seed) yielded a better result than placement 9 cm to the side of the seed. The depth of placement did not affect the yield. In most trials, placement of the fertilizer reduced the plant population only slightly as compared to broadcasting. The harmful effect in these trials was not significant even with the smallest distance from the seed, i.e. 3 cm. In practice, placement too close was shown to inhibit or to retard germination of the beet. It is therefore recommended that the fertilizer be placed 5—6 cm to the side and 3—4 cm below the seed.