Localizing EthioSIS Fertility Map Based Fertilizer Type Recommendation for Maize (Zea mays L.) in Coffee and Spice Production Belt in Yeki District, Southwest of Ethiopia

Abstract

Maize (Zea mays L) is an important smallholder crop in Ethiopia. However Yields are low because of low soil fertility and little fertilizer use. This field experiment was conducted to evaluate the effectiveness of NPS and NPSB, fertilizer types recommended by EthioSIS for the study domain during the 2018 main cropping season. The treatments were laid out in a randomized complete block design with four replications. Treatments were consisting of the two new fertilizer types (NPS and NPSB) kg ha-1 applied at rate of 150, 200, 250 each combined with two rates of urea kg ha-1 (100 and 150) and recommendation NP kg ha-1 (92N and 69 P2O5) and control. Data on selected soil physicochemical properties and maize nutrient uptake, use efficiency and profitability of fertilizer were taken. Yield and yield components of maize subjected to statistical analysis using SAS; mean treatment difference was compared using LSD. The results of the soils in the study area were slightly acidic (6.27 pH), Clay texture with moderate in TN (0.24%), available sulfur (13.14 ppm) and boron (0.99 ppm), high in K (550.80 ppm), OC (2.64 %) and CEC (30.89 cmol (+) kg-1), low in available P Olsen (5ppm). Maize plants in NPS and NPSB fertilizers treated plots had larger ear length (37.55cm)and cob length (18.05cm) and higher thousand grain weight (425.31gm), grain yield (8828.20 kg ha-1), straw yield (8760 kg ha-1), cob weight (1266.67 kg ha-1), biological yield (18521.5 kg ha-1), harvest index(0.47) and shelling percentage (0.88) compared to control and the recommended NP and the differences were highly significant (p<0.01). The number of ear per plant and number of grain rows per cob were none significantly (p>0.05) different, while number of grains per row were significant (p<0.05). Maize grain yield were highly significantly (p<0.01) and positively correlated with plant height, ear length, thousand seed weight, straw yield, biological yield, harvest index, shelling percentage and significantly (p<0.05) and positive correlation with number of grain per cob and none significantly (p>0.05) and positively correlated with ear height. Fertilizer NPS and NPSB along with urea and potassium had improved nutrient concentration, uptake, agronomic efficiency and apparent recovery as compared to recommended NP fertilizer, but it did not influence physiological P use efficiency. Application of NPSB at a rate of 250 with 100 urea and 100 KCl kg ha-1 had minimum acceptable marginal rate of return, highest net benefit and relatively small total cost of production was recommended for maize production in Yeki District. NPS applied at a rate of 250 kg ha-1 with a similar rate of urea and KCl as above can be considered as the second alternative. The result indicates the site-specific fertilizer type recommendations reformed better than the recommended NP both in agronomic and economic sense at Yeki District. However, further validation and demonstrations across multiple environments will be necessary to make a conclusive recommendation