Determination of Appropriate Fertilizer Rate for Forage and Seed Yields of Fodder Beet (Beta vulgaris)

Abstract

The study was conducted to determine the optimum level of chemical and farm yard manure fertilizer mixture for fodder beet (Beta vulgaris) production and to evaluate the effect of different mixed fertilizer rates on agronomic performance of fodder beet in the central highlands of Ethiopia. The experiment was designed in a factorial arrangement of four chemical fertilizer rates (0, 5/13, 10/23, 15/33, kg N/P₂O₅ ha^-1) and four farm yard manure fertilizer rates (0, 3, 6 and 9 t ha^-1 in dry matter basis) in a randomized complete block design with three replications. Data on plant survival rate, plant height, leaf yield, tuber yield, total forage yield and seed yield of fodder beet were collected and subjected to analysis of variance procedures of statistical analysis system (SAS) using general linear model to compare treatment means. The result showed that the interaction between inorganic and organic fertilizers application levels had significant (P<0.05) effect on all the aforementioned agronomic traits at Meraro. The establishment performance of fodder beet was very poor both at Holetta and Jeldu using direct seeding method of planting in the first year of production. But, using seedlings raised at nursery as a planting material at Holetta and Jeldu improved the plant survival rate by 52% and 49% respectively. Unlike at Holetta and Jeldu, establishment performances of fodder beet at Meraro using seeds as a direct planting material was promising and found to be an appropriate establishment method. The result showed that application of 10/23 kg N/P₂O₅ ha^-1 + 9 t FYM ha^-1 fertilizers as a mixture gave the highest plant survival rate (81.9%), plant height (30.3 cm), leaf DM yield (2.7 t ha^-1), tuber DM yield (10.3 t ha^-1) and total DM yield (13.0 t ha^-1) while the lowest values of the above traits were recorded from the control treatment. Application of fertilizers mixture at a rate of 10/23 kg N/P₂O₅ ha^-1 + 9 t FYM ha^-1 increased the survival rate, plant height, leaf DM yield, tuber DM yield and total DM yield by 34, 57, 286, 296 and 294% over the control treatment. But, the highest seed yield (3.0 qt ha^-1) was obtained by applying the highest level of fertilizer mixture (15/33 kg N/P₂O₅ ha^-1 + 9 t FYM ha^-1) which gave 900% seed yield advantage over the control treatment. Therefore, applying 10/23 kg N/P₂O₅ ha^-1 + 9 t FYM ha^-1 and 15/33 kg N/P₂O₅ ha^-1 + 9 t FYM ha^-1 fertilizer mixture were found to be the optimum fertilizers mixture rate for forage and seed yields of fodder beet. The study led to the conclusion that the combined application of the organic and inorganic fertilizers resulted in higher yields than sole application of each nutrient source. Therefore, this preliminary result recommends using FYM alongside with mineral fertilizers to increase forage and seed yields of fodder beet. However, further experimental research works should be carried out for more seasons and locations to assess the consistence of this finding.