Tomato yield, and water use efficiency as affected by nitrogen rate and irrigation regime in the central low lands of Ethiopia.

Tomato yield can be increased by the application of optimum water and fertilizer. A field experiment was conducted in Efratana Gidim district, North Shewa, Amhara, Ethiopia, during 2019 and 2020. The objective was to determine the nitrogen (N) rate and irrigation regime for optimum tomato yield and water use efficiency (WUE). The experiment consisted of three-irrigation regimes (75% ETc (Evapotranspiration from the crop), 100% ETc, and 125% ETc) and four nitrogen (N) rates (control; i.e. without N application1, 46 kg N ha-1, 92 kg N ha-1, and 138 kg N ha-1). The treatments were laid out in a split-plot design with four replications. The Irrigation regime were assigned to the main plot, while the N rate were assigned to the subplot. Data on growth, yield, and yield-related traits of tomatoes, include; plant height, number of fruit clusters per plant, fruit length, fruit diameter, number of marketable fruits, number of un-marketable fruits, the total number of fruits, marketable fruit yield, un-marketable fruit yield, total yield were collected. The data were subjected to analysis of variance using R studio. The results indicated that the experimental site had low total N content, and the application of N fertilizer significantly improved tomato yield. Increasing irrigation depth also significantly increased tomato yield. The result indicated that the highest mean marketable fruit yield (35,903 kg ha-1) was obtained from the combined application of 125% ETc with 92 kg N ha-1, while the lowest (13,655 kg ha-1) marketable fruit yield was obtained from 75% ETc with 92 kg N ha-1. The analysis of variance showed that the highest (5.4 kg m-3) WUE recorded from 75% ETc with 46 kg N ha-1 increased WUE by 77% (2.4 kg m-3) compared with the lowest (2.3 kg m-3) WUE recorded from 125% ETc with 0 kg N ha-1. The partial budget analysis also indicated that the highest net benefit (266,272 ETB (Ethiopian Birr) ha-1) and an acceptable marginal rate of return (1240%) for the invested capital was recorded from the combined application of 125% ETc with 92 kg N ha-1. Therefore, the application of 125% ETc with 92 kg N ha-1 resulted in the highest net benefit.

Precursor crop and vertisols type influences on teff (Eragrostis tef) response to fertilizer rates in the central highlands of Ethiopia.

Optimization of fertilizer-N and -P is important to highland production of teff (Eragrostis tef) on Vertisols of central Ethiopia but may be affected by precursor crop and Vertisols type. On-farm experiments were conducted in three major teff growing districts of North Shewa (Moretina jiru, Ensaro, and Merhabete) in 2019 and 2020 with the main objectives was to determine the effect of precursor crops and Vertisols type on teff response to N and P rates. The N x P factorial combinations include 0, 60, 120, 180, and 240 kg N ha-1 and 0, 30, 60, and 90 kg P ha-1 applied each to light and heavy Vertisols with either cereal or pulse precursor crops in each district. In Merhabete, grain yield was significantly influenced by Pc x Vt x N and Pc x Vt x P but always with the lowest and highest grain yield with 0 and 240 kg N ha-1, respectively. Yield was 394 % more with 240 kg N ha-1 compared with no N and P applied. The Vt x Pc × N interaction affected teff yield in Moretina Jiru as application of 240 kg N ha-1 increased teff yield by 440 %, 30 %, 23 %, and 7 % on light Vertisols compared with 200 %, 16 %, 13 %, and 2 % on heavy Vertisols. The 4-way interaction of Vt x Pc x N x P affected grain yield in Ensaro due to the low N and P status of the soil coupled with the distinct Vertisols type in the district. In all districts, yield response to N was greater with pulse compared with cereal precursor crops and with a greater response for heavy compared with light Vertisols in Moretina Jiru and Ensaro. In Moretina Jiru, application of 170 kg-1N and soil maintenance level of 30 kg-1 of P ha-1 are recommended as an economic optimum rate (EOR). In Ensaro, the EOR for teff following cereal on light Vertisols are 166 kg N ha-1 and 65 kg P ha-1. At Ensaro, needed rates for teff following pulse on light Vertisols are 198 N ha-1 and 48 kg P ha-1. At Ensaro, needed rates for teff following cereal on heavy Vertisols are 240 N ha-1 and 90 kg P ha-1. At Ensaro, needed rates for teff following pulse on heavy Vertisols are 240 N ha-1 and 80 kg P ha-1. In Merhabete, the EOR for teff following cereal on light Vertisols are 182 kg N ha-1 and 60 kg P ha-1. In Merhabete, needed rates for teff following pulse on light Vertisols are 206 N ha-1 and 64 kg P ha-1. In Merhabete, needed rates for teff following cereal on heavy Vertisols are 240 N ha-1 and 90 kg P ha-1. In Merhabete, needed rates for teff following pulse on heavy Vertisols are 218 N ha-1 and 58 kg P ha-1. Therefore, those N and P rate are recommended for the study area, soil type and precursor crops.