Evaluation of Different Indices of Sulfur Availability in Soils for Wheat (Triticum aestivum L.) Production in Ethiopia –II

Assefa Menna *

Department of Soil Science (DSS), Sokoine University of Agriculture (SUA), P.O.Box-3008, Morogoro, Tanzania and Pawe research center, Ethiopian Institute of Agricultural Research (EIAR), P.O.Box-2003, Addis Ababa, Ethiopia

Nyambilila Amuri

Department of Soil Science (DSS), Sokoine University of Agriculture (SUA), P.O.Box-3008, Morogoro, Tanzania.

Tekalign Mamo

Ministry of Agriculture (MoA), P.O.Box-62347, Addis Ababa, Ethiopia

Johnson M. R. Semoka

Department of Soil Science (DSS), Sokoine University of Agriculture (SUA), P.O.Box-3008, Morogoro, Tanzania

*Author to whom correspondence should be addressed.


Abstract

Using high-analysis fertilizers lacking adventitious sulfur (S), coupled with traditional cropping-systems that mine S from native soil, leads to S deficiency. However, under field conditions, S deficiency symptoms are not easily identifiable in cereals, because they are mistaken with those of Nitrogen (N). Hence, S availability indicators are necessary for rational fertilizer use. Eighteen explorative field experiments were conducted in 2012/2013 seasons in Central Highlands (HLs) of Ethiopia, with the purpose of evaluating S deficiency indicators in wheat, with the ultimate aim of setting critical-thresholds. In the study organic carbon (OC), and SO4-S in soils; total S and N/S ratio in grains were considered. Two levels of S (0 and 20 kg/ha); 2-levels of P (0 and 20 kg/ha); and 2-levels of N (0 and 69 kg/ha) as gypsum, triple-superphosphate (TSP) and urea, respectively were used. The experimental was laid out in randomized complete design (RCBD) in three replications. In the study, N/S ratio and S content in grain showed better association with S-uptake, with the degree of correlation, -0.83767 and 0.85547, respectively both significant at P<0.001. However, based on the minimum criteria set in literature, the total S in wheat grain showed better sensitivity, whereas N/S ratio was marginal. The critical-thresholds set at 90% Relative Yield (RY), were approximated to about 0.118% for total S, 14.7:1 for N/S ratio in grains; and 11.3 mg/kg for SO4-S in native soil. Therefore, wheat grains from S responsive sites and/or treatments can be distinguished from un-responsive ones, in which case much S response is expected for sites and/or treatments with total S content of <0.118%, N/S ratio >14.7:1 and SO4-S <11.3 mg/kg. In general, the results suggest that plant analysis, (in this case, grain), might be taken as a better tool for assessing S supply of soils or wheat crop than the soil analysis, and therefore, this preliminary result could be used as the basis for S research and as a provisional recommendation for wheat growers in Ethiopia.

 

Keywords: Sulfur, availability/deficiency indices, sulfur total, N/S ratio, SO4-S and organic carbon


How to Cite

Menna, Assefa, Nyambilila Amuri, Tekalign Mamo, and Johnson M. R. Semoka. 2015. “Evaluation of Different Indices of Sulfur Availability in Soils for Wheat (Triticum Aestivum L.) Production in Ethiopia –II”. International Journal of Plant & Soil Science 8 (4):1-11. https://doi.org/10.9734/IJPSS/2015/20513.