Soil Fertility Characterization and Response of Local Wheat Varity to Nitrogen Fertilization at Tembaro District, South Ethiopia

Abstract

The selected physico-chemical properties of the soil at Sigazo testing site was diagnosed to characterize the soil fertility status of the study area. In addition, a field experiment was conducted during the main rainy season of the 2009 at the testing site to determine the optimum rates of N fertilizer for local wheat variety production and to evaluate its effects on yield and yield components of the examination crop. The field experiment involved factorial combinations of five rates of N (0, 25, 50, 75 and 100 kg ha^-1) laid down in randomized complete block design with five replications. Soil samples were collected from freshly opened soil profile on genetic horizon bases and from the experimental plot (0-30 cm depth) before planting and after harvest to study those chosen soil properties. The moist soil color of the profile was very dark grayish brown (10YR 3/2) at the surface and brownish gray (2.5Y 6/2) at the bottom and with clay-loam texture. The bulk density values varied inconsistently with depth of the profile ranging from 1.14 g cm^-3 at the surface layer to 1.27 g cm^-3 at the third layer. Available water holding capacity of the horizons ranged from 109 to 128 mm m^-1 showing a decreasing trend with soil depth. Both the profile and the composite surface soil sample indicated that the soil of the site was slightly acidic to moderately alkaline in reaction (6.38 to 8.31), very low in OM (0.08 to 2.34%), very low in its total N (0.011 to 0.092%). The soil exchangeable bases was mainly dominated by Ca and Mg where the order of occurrence was Ca > Mg > Na >K. The CEC values were very high ranging from 62.7to 75.6 cmolc kg^-1. Application of different rates of N fertilizer significantly (P ≤ 0.01) influenced the whole crop parameters tested except stand count and grain filling period. The significantly different and maximum plant height (65.52 cm), fertile tillers (381), spike number (412), spikelets per spike (10.0) and spike length (6.52cm) were obtained from application of the highest N rate (100 Kg N ha^-1) whereas the minimum records were obtained from the control plot. Similarly, the maximum grain yield (2584.5 kg ha^-1), straw yield (3576.30 kg ha^-1), total biomass yield (6127.4 kg ha^-1) and 1000 grains weight (49.35 gm) were gained from application of the highest N rate showing a decreasing trend with declining N rate and the lowest records were obtained from the control plot. The grain and straw N contents and total N uptake were affected by the application of N fertilizer. They showed increasing trend with increasing N rate where the maximum records (2.45%, 0.45% and 79.08 kg ha^-1), respectively, were obtained at the highest N rate. The apparent recovery (AR) and agronomic efficiency (AE) of N responded positively to increasing N rate whereas the physiological efficiency (PE) of N exhibited decreasing trend with the increasing application of N, the highest PE was observed at the lowest N rate and vice versa.

Keywords: Soil fertility, Local wheat variety, N-fertilizer, Characterization

DOI: 10.7176/JBAH/13-13-01

Publication date:August 31^st 2023