Phosphorus Response and Fertilizer Recommendations Under Balanced Fertilizers for Wheat Grown on Nitisols in the Central Highlands of Ethiopia

Girma T. Chala

doi:10.7176/jnsr/10-1-02

Abstract

Phosphorous response and fertilizer recommendation under balanced fertilizer study was conducted for wheat grown on nitisols in Welmera district, West Shewa, in central highlands of Ethiopia. The experiment was arranged in a complete block design with five levels of phosphorous fertilizer (0, 10, 20, 30 and 40 kg ha -1 ) with three replications. Based on a yield difference between the phosphorus treatments and negative control treatments, Relative yield at 80% of sites responded to phosphorus fertilizer. Phosphorous fertilizer application at different rates wheat grain yield increased up to 20.6% when compared to the negative control treatment (zero p treatment). Extractable soil P concentrations (Bray II method, 0- 20 cm depth) three weeks after planting significantly responded to P fertilizer rate. Relative yield correlated with soil phosphorous values revealed that the soil phosphorous levels greater than 14.8 mg kg -1 (critical phosphorous concentration) was found to be optimum for production of wheat on nitisols area. Phosphorous requirement factor (Pf) average was calculated from soil phosphorous values of all treatments for the study area was 11.13. In the absence of a soil test, a recommendation of 30 kg P ha -1 to prevent a potential loss of wheat. Further study is needed to determine interaction effect of phosphorus with other nutrient requirement of wheat involving more soil types and agro-ecological zones supported by appropriate soil and plant analysis. Keywords: Nitisols, P concentration, Phosphorus, P requirement factor, Relative yield, Wheat DOI : 10.7176/JNSR/10-1-02 Publication date: January 31 st 2020

Highlights

Soil fertility depletion and soil quality decline are the main constraints affecting the yield and sustainability of crop production in Ethiopia
Wheat is grown over a large area (1.63 million ha), but productivity is as low as 2.6 t ha-1 in the Ethiopia and in the west Shewa zone, 2.7 t ha-1[2].This is due to declining soil fertility, low fertilizer usage, lack of resistant varieties to rust diseases [3, 4]
Soil samples were analyzed for pH using a ratio of 2.5 ml water to 1 g soil available P using Bray2 method, organic C content using according to Walkley and Black [19], total N content using Kjeldahl method, exchangeable cations and cation exchange capacity (CEC) using ammonium acetate method at the soil and plant analysis laboratory of Holeta Agricultural Research Center

Summary

Introduction

Balanced fertilizers in blend form have recommended ameliorating site specific nutrient deficiencies and thereby increasing productivity. The need for site-specific fertilizer prescriptions is increasingly apparent, fertilizer trials involving multi-nutrient blends that include micronutrients are rare in Ethiopian context. Wheat is grown over a large area (1.63 million ha), but productivity is as low as 2.6 t ha-1 in the Ethiopia and in the west Shewa zone, 2.7 t ha-1[2].This is due to declining soil fertility, low fertilizer usage, lack of resistant varieties to rust diseases [3, 4]. Limited use of legumes in the cropping system, continuous cropping, and applications of suboptimal rates of mineral fertilizers have aggravated the decline in soil fertility and crop yield [5,6,7]. The rate of chemical fertilizer application is low in the country due to unaffordable price for resource-poor smallholder farmers [8]

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