Groundnut (Arachis hypogaea L.) Response to Nitrogen Fertilizer and Earthing Up Practices in the Tigray Region of Ethiopia

To increase groundnut yields, integrated agronomic techniques must be implemented. The current study focuses on using starter nitrogen fertilizer in conjunction with earthing up for groundnut cultivation. Three replications and a factorial combination were used in the complete randomized block design of the experiment. Two types of earthing up (no earthing up and earthing up) and four levels of nitrogen fertilizer (0, 15, 30, and 45 kg ha-1) were used in the treatment combinations. For each of the Hamedo 1 and Hamedo 2 experimental sites, two undisturbed and two disturbed composite soil samples were collected at a depth of 20 cm before sowing. The data analysis showed that neither the combination application of N fertilizer and earthing up nor the individual independent applications of N fertilizer and earthing up had a significant effect on groundnut flowering and maturity. Groundnut plant height, number of branches per plant, number of pods per plant, number of seeds per plant, seed weight per plant, and haulm yields were not significantly affected by earthing up alone or by the co-application of nitrogen fertilizer and earthing up. On the other hand, the exclusive use of nitrogen fertilizer significantly affected groundnut plant height, the number of branches per plant, the number of pods per plant, the number of seeds per plant, seed weight per plant, and haulm yield. Applying 45 kg ha-1 of nitrogen fertilizer to the Hamedo 1 and Hamedo 2 trial sites enhanced the haulm yield by 70.53% and 78.76%, respectively, compared to the unfertilized plots. Individual applications of nitrogen fertilizer, earthing up, or a combination of both had a significant effect on groundnut pod and kernel yields. In comparison to plots that received a combined application of 45 kg ha-1 of nitrogen fertilizer and earthing up, the Hamedo 1 and Hamedo 2 trial sites exhibited increases in pod yields of 57.73% and 55.97%, respectively, when earthing up was combined with 15 kg ha-1 of nitrogen fertilizer. In the same way, applying 15 kg ha-1 of nitrogen fertilizer to the earthing-up soil in the Hamedo 1 and Hamedo 2 experimental sites boosted the kernel yields by 70.05% and 75.43%, respectively, in comparison to soil earthing-up plots that received 45 kg ha-1 nitrogen. The findings of the economic and agronomic analyses showed that applying nitrogen fertilizer and earthing up together greatly increases groundnut yields and revenues. Therefore, to increase groundnut yields and receive more financial advantages, farmers can consider the combined application of 15 kg ha-1 of nitrogen fertilizer and earthing-up.