Response of Wheat to NP Fertilizer Rates, Precursor Crops and Types of Vertisols in Central Highlands of Ethiopia

Adamu Molla

doi:10.5539/jas.v10n4p231

Abstract

The objective of this work was to evaluate the performance of bread wheat under different NP fertilizer rates, precursor crops and types of Vertisols in order to determine higher agronomic and economic yielding combination of levels of these factors. The first field experiment comparing factorial combinations of 0, 80, 160 and 240 kg N ha-1 with 0, 20, 40 and 60 kg P ha-1 in 2006-2007 on four farmers’ fields, with four replications in each field, resulted in recommendation of 151/40 and 192/60 kg N/P ha-1 for further on-farm evaluation as compared to old recommendation (87/20 kg N/P ha-1) and to the farmers’ highest rate (256/80 kg N/P ha-1) under dominant precursor crops and types of Vertisols. Thus the second field experiment compared the above four treatments on 32 farmers’ fields (no replication in each field) on lentil (Lens culinaris) and tef (Eragrostis tef) precursors on Bushella and Mererie Vertisols in 2012-2013. Grain yield response of bread wheat to N/P rates following lentil precursor on Mererie was significantly (p < 0.01) quadratic while responses following lentil precursor on Bushella, and tef precursor on both types of Vertisols were significantly (p < 0.05) linear. Application of the highest rate (256/80 kg N/P ha-1) on wheat following lentil precursor gave grain yield of 5001 and 3407 kg ha-1 on Mererie and Bushella Vertisols, respectively. The same rate on wheat following tef precursor gave grain yield of 4143 and 3904 kg ha-1 on Mererie and Bushella Vertisols, respectively. However, application of 167/45 kg N/P ha-1 was more economical (79.7-134.1% marginal return) and is suggested to be promoted for bread wheat production following tef and lentil precursors on both types of Vertisols of the test locations and similar areas in the central highlands of Ethiopia. Further studies are also suggested to improve fertilizer use efficiency and reduce such high rate recommendations which could pose environmental risks.

Highlights

Wheat with production area of about 1.66 million hectares is one of the most important cereal food crops cultivated in Ethiopia, ranking fourth after teff (Eragrostis tef), maize (Zea mays) and sorghum (Sorghum bicolor) in area coverage (Central Statistical Agency, 2016)
The Ethiopian highland Vertisols, higher than 1500m altitudes above sea level, covers about 7.6 million hectares, of which 35000 ha of land on the high elevation of Enewarie plateau is considered as wheat belt that has been supported by relatively efficient traditional drainage method of smallholder farmers in the central highlands of Ethiopia (Asamenew, Jutzi, Tedla, & McIntire1988)
Simple random field observations by the author of this paper in 2006 growing season revealed that smallholder farmers believe types of Vertisols affect productivity: relatively heavy Vertisols called Mererie is more productive than relatively light Vertisols called Bushella

Summary

Introduction

Wheat with production area of about 1.66 million hectares is one of the most important cereal food crops cultivated in Ethiopia, ranking fourth after teff (Eragrostis tef), maize (Zea mays) and sorghum (Sorghum bicolor) in area coverage (Central Statistical Agency, 2016). Waterlogging on Vertisols, soil degradation, declining soil fertility and low input production system have been some of the most important constraints limiting food production in Ethiopia (Abate, de Brauw, Minot, & Bernard, 2014; FAO, 2013; Henao & Baanate, 1999; Hurni, 1983, 1988). Smallholder farmers’ fertilizer application rate for wheat production ranged from 63/14 to 161/29 kg N/P ha-1 as was determined from 28 farmers in Deneba and Enewarie areas. This indicates that farmers’ application rates were by far higher than the old recommendation, which is 87/20 kg ha-1 of N/P for Vertisols in general

Objectives

Methods

Results

Discussion

Conclusion