Effect of Long‐term Application of Farmyard Manure on Growth and Quality of Sugar Beet

Abstract

Field trials were conducted for two years on two farms which differed in long-term application of pig slurry in order to study the effects of long-term organic manuring, timing of slurry application (no slurry, sluny autumn, slurry spring) and additional doses of mineral N-fertilizer (0, 80, 160, 240 kg N/ha) on growth and quality of sugar beet.The results can he summarized as follows:1. The effect of slurry application on growth of sugar beets varied markedly with the long-term differences in farm management. On the "arable farm" yield of beet roots increased substantially after slurry application and could not be replaced by higher doses of mineral N fertilizer. It is concluded therefore that "special effects" of farmyard manure are involved. On the "livestock farm", however, highest beet yields were obtained on plots without slurry. Additionally slurry application caused a significant decrease in beet yields.2. Sugar beets without slurry treatment always developed higher sugar contents and lower concentrations of alpha-amino-N, sodium and potassium as compared to beets from plots with slurry application.3. Despite the decline in sugar content, sugar yield greatly increased by slurry application on the "arable farm". The average increase in sugar yield was lOdt/ha (= 8 %) with slurry application in autumn and amounted to 16dt/ha (= 14%) with spring application. On the livestock farm however, additional applications of slurry caused a decline in sugar yields in both years because of lower sugar contents and decrease in beet yields.4. The utilization rate of slurr)'-N, depending mainly on time of application, annual rainfall and soil N mineralization, varied from 6-41 %. On the "livestock farm" the utilization of slurry-N was only half of the rate obtained on the "arable farm". 5. The application of small doses of slurry may cause a significant yield increase on farms without or only less livestock, while on farms with intensive livestock production continous slurry application needs to be considered as an expensive form of waste disposal. Therefore farms with high livestock density are advised to sell slurry to neighbouring farms without or only low animal production at a fair price for their mutual advantage.